Mitral Regurgitation

Mitral regurgitation is the most common valvular abnormality in developed countries and is the second most frequent indication for valve surgery in Europe. MR can be broadly categorised as either primary, with intrinsic abnormalities of the leaflet and/or subvalvular apparatus, or secondary (functional) when MV anatomy is normal but abnormalities of the LV and/or LA disrupt normal valvular function. (BSE mitral guideline 2021)

Since the onset of MR is acute, the sudden increase in volume results in a rapid and significant increase in LAP with no immediate change in the chamber size (non-compliant). Hence acute severe MR may be associated with a normal size LA. (BSE mitral guideline 2021)

Mitral regurgitation (MR) can be classified as primary (organic) or secondary (functional). Primary MR is due to a structural lesion in one or several components of the mitral valve (MV) apparatus, whereas secondary MR is caused by left ventricle (LV) systolic dysfunction/dilatation without valvular abnormalities. (Oxford Critical Care Echo)

The presence of certain features in 2D imaging raises the possibility of acute MR (e.g. chordal rupture and papillary muscle rupture), in comparison with chronic MR (e.g. myocardial ischaemia and dilated cardiomyopathy). (Oxford Critical Care Echo)

The examination also provides clues to whether regurgitation is acute or chronic in duration. (Otto, Clinical Echocardiography 6e)

Trivial or physiologic mitral regurgitation can occur in structurally normal MVs. (Practical Perioperative TOE)

According to aetiology, MR can be classified as primary (i.e. organic/structural: intrinsic valvular disease) or secondary (i.e. functional/non-structural: without evident structural abnormalities of the mitral valve). Causes of primary MR include most commonly degenerative disease (Barlow, fibroelastic degeneration, Marfan, Ehlers-Danlos, annular calcification), rheumatic disease, toxic valvulopathy, and endocarditis. Ruptured papillary muscle secondary to myocardial infarction is included as primary ischaemic MR. (EACVI valvular regurgitation recs)

Secondary MR develops despite a structurally normal mitral valve in the context of ischaemic heart disease, dilated cardiomyopathy, or severe LA dilatation. It results from an imbalance between the forces acting on mitral leaflets and LV-generated closing forces. LV remodelling and the resulting tethering of the mitral valve play a major role in the genesis of secondary MR. Chronic secondary ischaemic MR results, in 95% of the cases, from a type IIIb dysfunction. (EACVI valvular regurgitation recs)

The commonest causes of moderate or severe MR include degenerative disease (also referred to as mitral valve prolapse (MVP)) accounting for around 60%, rheumatic valve disease seen in 15% and secondary MR responsible for approximately 20% of all cases. (BSE mitral guideline 2021)

The most frequent cause of native mitral regurgitation in industrialized nations is myxomatous degeneration. Rarely, myxomatous degeneration is associated with systemic diseases such as Marfan and Ehlers-Danlos syndromes. (Practical Perioperative TOE)

MR due to LV dilation and systolic dysfunction, in patients with normal valve leaflets and chordae, often is called functional MR. The mechanism of functional MR remains controversial, with some studies suggesting abnormal orientation of the papillary muscles and others suggesting annular dilation. (Otto, Clinical Echocardiography 6e)

Common causes include degenerative diseases (e.g. myxomatous degeneration and Marfan syndrome), rheumatic disease, infective endocarditis, or chordae tendineae/papillary muscle rupture. (Oxford Critical Care Echo)

Ischaemic heart disease and dilated cardiomyopathy are common causes that lead to secondary MR. Myocardial ischaemia can cause regional LV dysfunction with abnormal papillary muscle contraction and tethering of the MV. The resulting jet is typically eccentric. In dilated cardiomyopathy, a centrally located jet is a result of a combination of annular dilatation, papillary muscle displacement and impaired LV systolic contraction. (Oxford Critical Care Echo)

Rheumatic MR, like rheumatic mitral stenosis, is characterized by some degree of commissural fusion, but chordal fusion and shortening are more prominent. Endocarditis results in MR by leaflet destruction, perforation, or deformity. Marfan syndrome is associated with a long, redundant anterior leaflet that sags into the LA in systole. (Otto, Clinical Echocardiography 6e)

The mechanism is defined according to leaflet motion using Carpentier's classification and can be: normal, MR results from isolated annular dilatation (either from LA or LV dilatation) or leaflet perforation (type 1); excessive, MR results from leaflet prolapse (type 2); or restricted, MR can be due to leaflet restriction and retraction (type 3a) or LV remodelling with underlying wall motion abnormalities (type 3b). (BSE mitral guideline 2021)

Type 1 - Normal leaflet motion. The predominant cause of type 1 MR is annular dilation. Although this is more commonly due to LV dilatation, significant LA dilatation is also increasingly recognised as an underlying cause (typically associated with atrial fibrillation). However, in rare cases, type 1 MR may be caused by a leaflet perforation secondary to either infective endocarditis or an iatrogenic complication of cardiac surgery. (BSE mitral guideline 2021)

Type 2 MR - Excessive leaflet motion. Type 2 MR occurs secondary to leaflet prolapse. Severe MR secondary to papillary muscle rupture may be a mechanical complication following myocardial infarction (MI) and is a rare cause of type 2 MR. (BSE mitral guideline 2021)

Type 3 - Restricted leaflet motion. Type 3 MR is sub-divided into two categories: leaflet restriction during both systole and diastole (type 3a) and leaflet restriction during systole only (type 3b). Type 3a is more frequently secondary to leaflet thickening and fusion. Type 3b occurs when the mitral leaflets are structurally normal but underlying LV disease results in leaflet tethering into LV and, consequently, leaflet restriction (typically seen in ischaemia of the infero-lateral wall with asymmetric systolic tethering of the posterior leaflet). It may also be seen when global LV dilation results in symmetric bileaflet tethering and reduced coaptation. (BSE mitral guideline 2021)

Type 1 dysfunction is defined as mitral regurgitation in the presence of normal leaflet motion. Examples include annular dilatation, leaflet perforation, and leaflet cleft. Type II dysfunction refers to excessive leaflet motion. Examples include leaflet prolapse and flail due to degenerative disease. Type III dysfunction refers to restricted leaflet motion. Type IIIa is leaflet restriction that occurs predominantly in diastole. Examples include rheumatic disease, radiation-induced valvulopathy, and dystrophic calcification. Type IIIb is leaflet restriction that occurs predominantly in systole. Type IIIb may be symmetric or asymmetric. Examples include dilated cardiomyopathy (symmetric) and myocardial infarction (asymmetric). (Otto, Clinical Echocardiography 6e)

Type 1 - Leaflet motion is normal. Mitral regurgitation results from annular dilatation, leaflet clefts, leaflet perforation, or leaflet destruction (e.g., due to endocarditis). Mitral regurgitation is typically central. Type 2 - Leaflet motion is excessive and may be classified as prolapse or flail. The most common cause is myxomatous degeneration with or without chordal rupture. Regurgitation is usually eccentric and directed away from the diseased leaflet. Type 3 - Leaflet motion is restricted. Type 3 may be further subdivided into structural (Type 3a), in which leaflets are diseased, and functional (Type 3b), in which leaflets are structurally normal but tethered by the papillary muscles or underlying myocardium. (Practical Perioperative TOE)

Type I: normal mobility of leaflets with annular dilation that causes a central jet or perforation of a leaflet. Type II: excessive mobility with ruptured chords or severe prolapse, causing a jet directed to the opposite side of the affected leaflet. Type III: restricted mobility due to shrinkage of the subvalvular apparatus (IIIa) or displacement and tethering of the papillary muscle that causes apical displacement of the leaflet (IIIb). In type III regurgitation the jet is aimed at the same side of the affected valve. (Oxford Critical Care Echo)

Severe chronic primary mitral regurgitation increases LV preload and will eventually lead to chamber dilation, eccentric hypertrophy and ultimately impaired function, all of which identify a suboptimal prognosis. (BSE mitral guideline 2021)

LA dilatation secondary to volume overload is an expected finding in those with chronic severe MR. Normal LA volume, therefore, rules out chronic severe MR with near certainty. Given the rapid onset, acute severe MR may be associated with little or no chamber dilation or adverse remodelling. (BSE mitral guideline 2021)

In the chronic compensated phase (the patient could be asymptomatic), the forward stroke volume is maintained through an increase in LV ejection fraction. Such patients typically have LV ejection fraction >65%. In this phase, the LA remodels and dilates but the LA pressure is often normal. In the chronic decompensated phase the forward stroke volume decreases and the LA pressure increases significantly. The LV contractility can thus decrease silently and irreversibly. (EACVI valvular regurgitation recs)

Secondary MR has a different physiology, as it is the consequence of an initial ventricular disease. The LV and LA dilatation are in excess to the degree of MR. The LA pressure is often elevated despite lower regurgitant volume than in primary MR. (EACVI valvular regurgitation recs)

MR results in LV volume overload because of the increase in total LV stroke volume as blood is ejected both forward into the aorta and retrograde across the mitral valve. With acute MR, the LV empties more completely (i.e., ejection fraction increases), such that forward cardiac output is maintained. With compensated chronic regurgitation, LV diastolic volume increases and ejection fraction is normal, such that end-systolic volume is within the normal range or only mildly increased. (Otto, Clinical Echocardiography 6e)

The LA gradually dilates to accommodate the regurgitant volume while maintaining a normal pressure because of an increase in compliance (i.e., the LA pressure-volume relationship is shifted downward and to the right). With acute MR, the regurgitant volume is delivered into a small, noncompliant LA, resulting in a significant increase in pressure and a v-wave in the LA pressure curve. (Otto, Clinical Echocardiography 6e)

Chronic severe MR will lead to LV dilatation and subsequent impaired systolic function with evidence of enlarged LA, whereas acute severe MR is typically associated with a normal-sized LA and LV with hyperdynamic LV contractile function. (Oxford Critical Care Echo)

Spherical enlargement of the left ventricle with eccentric hypertrophy (i.e., wall thickness is increased in proportion to the increase in LV size). End-diastolic volume increases before end-systolic volume. (Practical Perioperative TOE)

Work through it in a logical order: define the valve and the mechanism of regurgitation, build severity from qualitative to quantitative measures, assess the secondary effects on the left atrium, left ventricle and pulmonary pressures, then integrate with the clinical picture — always distinguishing primary from secondary disease, and acute from chronic.

The TTE parasternal short-axis view and the TOE transgastric view at 0 degrees permit the assessment of the six scallops and, with colour Doppler imaging, the localization of the origin of the regurgitant jet may identify prolapsing segments. The TTE parasternal long-axis and the TOE sagittal view at 120 degrees classically show A2 and P2. With TOE, angulation of the probe towards the aortic valve allows the visualization of A1 and P1 and towards the tricuspid, the visualization of A3 and P3. In apical four-chamber view, appreciation of A3, A2, and P1 (internal to external) is possible. (EACVI valvular regurgitation recs)

The key imaging planes include oesophageal views at 0, 50, 90 and 135 degrees and trans-gastric views at 0 and 90 degrees. Landmarks are essential in identifying structures (aortic valve adjacent to anterior leaflet, left atrial appendage identifies lateral portion of valve P1/A1/ALC, inter-atrial septum (IAS) identifies medial portion of MV, typically P3/A3). (BSE mitral guideline 2021)

The examination consists of four standard midesophageal views (four-chamber, commissural, two-chamber, and long axis) and two transgastric views (basal short axis and two-chamber). (Practical Perioperative TOE)

Mitral segments seen in the midesophageal views (left to right across the screen): ME four-chamber - A2/P2. ME commissural - P3/A2/P1. ME commissural with left turn of probe - A3/A2/A1. ME commissural with right turn of probe - P3/A3/A2/A1. ME long axis - P2/A2. ME long axis with left turn of probe - P1/A1. ME long axis with right turn of probe - P3/A3. (Practical Perioperative TOE)

The commissural view is useful for assessing which segments are regurgitant. On color flow Doppler, regurgitation arising from the left coaptation point indicates involvement of the posteromedial segments (P3/A3); regurgitation arising from the right coaptation point implies involvement of the anterolateral segments (A1/P1). (Practical Perioperative TOE)

The midesophageal long-axis view cuts the coaptation line perpendicularly through P2/A2. Since the image plane cuts the coaptation line perpendicularly, the observed base-to-tip leaflet length accurately reflects the true leaflet length. For the same reason, it is the appropriate view for assessing the width of the vena contracta. The image plane passes through the 'high' (more basal) axis of the mitral annulus and is therefore the appropriate view for assessing leaflet prolapse. (Practical Perioperative TOE)

The transgastric basal short-axis view shows the MV en face and allows visualization of all six mitral segments. P3 is closest to the apex of the sector scan, the posteromedial commissure is in the upper left, and the anterolateral commissure is in the lower right of the image. It is also called the 'fish mouth' view. (Practical Perioperative TOE)

The standard PLAX view will provide assessment of the middle portions of both leaflets (A2 and P2). Tilting of the probe towards the aortic valve allows assessment of A1 and P1, while tilting towards the tricuspid valve allows the identification of A3 and P3 segments. (Oxford Critical Care Echo)

The mid-oesophageal four-chamber (ME 4Ch) view, with the transducer angled at 0-10 degrees, allows assessment of the A2-P2 coaptation. The ME mitral commissural view, with transducer angle 50-70 degrees, examines P3-A2-P1. The ME two-chamber view (ME 2Ch), with transducer angle 80-100 degrees, examines P3-A3A2, and the ME long axis view (ME LAX), with transducer angle 120-140 degrees, examines P2-A2. (Oxford Critical Care Echo)

In addition to parasternal long- and short-axis views, apical four-chamber and long-axis views are useful because they are nearly orthogonal to each other. However, signal attenuation at the depth of the LA limits the utility of apical views if ultrasound penetration is suboptimal. (Otto, Clinical Echocardiography 6e)

Along the free edge of the posterior leaflet are a series of indentations that divide the posterior leaflet into three scallops of roughly equal size: P1, P2 and P3. Although similar indentations are not present on the anterior leaflet, the corresponding regions opposing the posterior scallops are labelled A1, A2 and A3. Where the two leaflet tips meet is described as the zone of coaptation. The coaptation zone (leaflet apposition) is at least 5 mm in height in a competent mitral valve. (BSE mitral guideline 2021)

They are each divided into three scallops: A1, A2, A3 and P1, P2, P3. A1 and P1 correspond to the external, anterolateral portion of their respective leaflet, close to the anterolateral commissure, and the left atrial appendage. In opposite, A3 and P3 are internal, close the posteromedial commissure, and the tricuspid annulus. (EACVI valvular regurgitation recs)

Leaflet prolapse: where there is excessive leaflet motion and displacement of the tip of one or more segments of the mitral valve by 2 mm relative to the hinge points of the leaflets. Flail leaflet segment: where the free edge (tip) of the leaflet has lost its support through rupture of a primary chord(s), resulting in the eversion of the leaflet tip into the LA. (BSE mitral guideline 2021)

Mitral valve prolapse is defined as abnormal systolic displacement of 1 (posterior prolapse) or both leaflets into the left atrium below the annular (bileaflet prolapse). (EACVI valvular regurgitation recs)

The ASE/SCA guidelines use the Carpentier nomenclature: A1, A2, and A3 represent the anterior leaflet's anterolateral, middle, and posteromedial segments, respectively, and P1, P2, and P3 represent the posterior leaflet's anterolateral, middle, and posteromedial scallops, respectively. (Practical Perioperative TOE)

Prolapse is said to occur when the body of a leaflet domes above the level of the mitral annulus in systole (by more than 2 mm, using TTE criteria). With TEE, prolapse should be assessed in the midesophageal long-axis view at end systole. The leaflet tip is directed toward the left ventricle, and a coaptation defect may be visible. (Practical Perioperative TOE)

A flail leaflet results in a visible coaptation defect with the leaflet tip directed toward the left atrium throughout systole. The cause is usually torn chordae in association with myxomatous change. In general, regurgitation due to a flail leaflet is more severe and develops more rapidly than that associated with leaflet prolapse. A ruptured papillary muscle also causes leaflet flail. (Practical Perioperative TOE)

The term prolapse of the mitral leaflet indicates that the chordal connections of the leaflet to the papillary muscle are intact so that, regardless of the severity of prolapse, the tip of the leaflet still points toward the LV apex. With chordal rupture, the mitral leaflet segment becomes 'flail,' and the tip of the flail segment points toward the roof of the LA. (Otto, Clinical Echocardiography 6e)

Ischemic MR is characterized by restricted leaflet motion, with tethering of valve closure resulting in the appearance of 'tenting' or tethering of the mitral valve in systole. (Otto, Clinical Echocardiography 6e)

Using the parasternal long-axis TTE view, annular dilatation is identified when the ratio annulus/anterior leaflet is >1.3 (in diastole) or when the annulus diameter is >35 mm. (EACVI valvular regurgitation recs)

An understanding of the mechanism of valve failure is critical in determining patient selection for suitability of valve intervention, including repair. A flail segment from chordal rupture or identification of complete loss of coaptation with a visible coaptation gap are two specific mechanisms indicative of severe valve regurgitation. (BSE mitral guideline 2021)

The following points should be addressed during echocardiographic assessment of mitral regurgitation: The pathologic process underlying the regurgitation (myxomatous degeneration, rheumatic disease, endocarditis, or ventricular dysfunction). The mechanism of regurgitation (prolapse, flail, restriction, perforation, or cleft). The location and extent of the lesion (which segments are involved and whether the lesion involves the commissures). (Practical Perioperative TOE)

Despite the important role of color flow Doppler in assessing mitral regurgitation, most of this information is gained from careful 2-D imaging. (Practical Perioperative TOE)

The first step in assessment is evaluation of valve anatomy and motion, as well as LV size and systolic function, to determine the cause of regurgitation, most importantly whether valve dysfunction is due to primary leaflet disease or is secondary to LV dilation and systolic dysfunction. (Otto, Clinical Echocardiography 6e)

Color Doppler imaging is helpful for determining the mechanism of mitral regurgitation. The origin of the regurgitant jet as it crosses the valve indicates the area of inadequate coaptation. The direction of the regurgitant jet in the atrium tends to be anterior with posterior leaflet dysfunction, posterior with anterior leaflet dysfunction, and central with functional regurgitation. Complex or multiple jets are seen when more than one mechanism of regurgitation is present. (Otto, Clinical Echocardiography 6e)

Leaflet perforation is characterized by the presence of one or more regurgitant jets that do not appear to arise from the coaptation line. The presence of two separate proximal convergence zones should alert the echocardiographer to the possibility of perforation. (Practical Perioperative TOE)

Systolic anterior motion (SAM) refers to displacement of the anterior leaflet of the MV into the LVOT during systole. The consequences of SAM are twofold: (1) a systolic coaptation defect of the MV, which results in a late-peaking, posteriorly directed jet of mitral regurgitation, and (2) LVOT obstruction. (Practical Perioperative TOE)

By using a combined assessment that integrates the aforementioned standard and modified views, the direction of any central or eccentric jets, together with the underlying mechanism can often be identified. (Oxford Critical Care Echo)

The initial identification of MR and basic evaluation of severity is based on the visual interpretation of jet size by colour flow Doppler; the principle being that greater MR severity results in a larger jet within the LA. It is important to note that the Nyquist limit should be set to a range of 50-60 cm/s and colour gain optimised when assessing blood flow. (BSE mitral guideline 2021)

Colour flow imaging is the most common way to assess MR severity. The general assumption is that as the severity of the MR increases, the size and the extent of the jet into the LA also increase. For a similar severity, patients with increased LA pressure or with eccentric jets that hug the LA wall or in whom the LA is enlarged may exhibit smaller jets area than those with normal LA pressure and size or with central jets. (EACVI valvular regurgitation recs)

Nevertheless, the detection of a large eccentric jet adhering, swirling, and reaching the posterior wall of the LA is in favour of severe MR. Conversely, small thin jets that appear just beyond the mitral leaflets usually indicate mild MR. (EACVI valvular regurgitation recs)

The shape and direction of the jet are helpful in diagnosis; an eccentric jet suggests pathologic regurgitation and provides clues to the mechanism of regurgitation. Abnormalities of the posterior leaflet tend to result in an anteriorly directed jet, whereas anterior leaflet and papillary muscle dysfunction tend to result in a posteriorly directed jet. Dilation of the LV or mitral annulus results in a central, symmetric regurgitant jet. (Otto, Clinical Echocardiography 6e)

Jets are 'pulled' toward adjacent walls (e.g., MR in the LA) if within a critical distance from the wall at the entry site. Eccentric jets that adhere to the wall of the chamber have a smaller color jet area on two-dimensional (2D) color flow imaging (and a smaller three-dimensional [3D] volume) because entrainment of additional fluid elements into the jet occurs on only one side instead of on all sides, as with a central jet. (Otto, Clinical Echocardiography 6e)

In general, a small central jet with a non-oblique view is consistent with mild MR, while the presence of a large central jet (usually >8 cm2 or >40% of LA area) is indicative of severe MR. Conversely, a large eccentric jet adhering, swirling, and reaching the posterior wall of the LA is a likely indicator of significant MR. (Oxford Critical Care Echo)

In general, small jets (<4 cm2, <20% of LA area) are consistent with mild mitral regurgitation and large jets (>10 cm2 or >40% of LA area) are severe. All wall-hugging jets should be considered severe until proven otherwise. (Practical Perioperative TOE)

The density and velocity of the CW Doppler signal can also be used as a qualitative guide to MR severity. Dense signals are suggestive of more severe MR, while faint signals are suggestive of mild regurgitation. Additionally, because of rapid pressure equalisation, a triangular waveform with peaking in early systole is suggestive of very severe or torrential, often acute MR. (BSE mitral guideline 2021)

Peak MR jet velocities by CW Doppler typically range between 4 and 6 m/s. The velocity itself does not provide useful information about the severity of MR. Conversely, the signal intensity (jet density) of the CW envelope of the MR jet can be a qualitative guide to MR severity. A dense MR signal with a full envelope indicates more severe MR than a faint signal. The CW Doppler envelope may be truncated (notched) with a triangular contour and an early peak velocity (blunt). This indicates elevated LA pressure or a prominent regurgitant pressure wave in the LA due to severe MR. (EACVI valvular regurgitation recs)

The signal density of the transmitral jet on CW Doppler is determined by both the regurgitant blood flow and the Doppler gain setting. A systolic signal that is complete, and of equal density to the diastolic signal, suggests severe regurgitation. A systolic signal that is complete but less dense than the diastolic signal suggests moderate regurgitation. An incomplete systolic signal suggests mild regurgitation. (Practical Perioperative TOE)

Regurgitation of a large volume of blood into the left atrium causes a late systolic reduction in the transmitral gradient due to a sharp rise in the LA pressure (seen as a V wave on the LA pressure trace). This causes a late systolic reduction in regurgitant jet velocity, which gives the Doppler map an asymmetrical shape and is known as the V wave cutoff sign. (Practical Perioperative TOE)

A weak signal reflects mild regurgitation, whereas a signal nearly equal in intensity to antegrade flow reflects severe regurgitation. Moderate regurgitation has intermediate signal strength relative to antegrade flow. (Otto, Clinical Echocardiography 6e)

The CW Doppler spectral recording of MR shows a rapid increase in velocity during isovolumic contraction (proportional to the rate of rise in LV pressure or dP/dt) from baseline to a maximum velocity of 5 to 6 m/s. An increase in end-systolic LA pressure (v-wave) results in a late-systolic decline in the instantaneous pressure gradient and in the instantaneous velocity. (Otto, Clinical Echocardiography 6e)

The signal intensity of the MR jet's CW envelope can be a qualitative guide to severity. A dense MR signal with a full envelope indicates a more severe regurgitation, as opposed to a faint signal. A truncated CW Doppler envelope with a triangular contour and an early peak velocity indicate elevated LA pressure as a result of severe MR. (Oxford Critical Care Echo)

CW Doppler signal - Mild: Faint signal, parabolic; Moderate: Usually dense, parabolic; Severe: Dense signal, early peaking and triangular. (Oxford Critical Care Echo)

As mitral regurgitation becomes more severe, the associated rise in left atrial pressure increases the resistance to forward blood flow from the pulmonary veins during systole, leading to reduced (blunted) systolic pulmonary vein flow. With severe regurgitation, LAP is high and blood is forced back into the veins during systole (reversed systolic pulmonary flow). (BSE mitral guideline 2021)

With increasing the severity of MR, there is a decrease of the S-wave velocity. In severe MR, the S-wave becomes frankly reversed. Atrial fibrillation and elevated LA pressure from any cause can blunt forward systolic pulmonary vein flow. Therefore, blunting of pulmonary venous flow lacks of specificity for the diagnosis of severe MR, whereas systolic pulmonary flow reversal is specific for severe MR. (EACVI valvular regurgitation recs)

As unilateral pulmonary flow reversal can occur at the site of eccentric MR jets if the jet is directed into the sampled vein, sampling through all pulmonary veins is recommended, especially during TOE. (EACVI valvular regurgitation recs)

Trivial or mild regurgitation is generally associated with a normal flow pattern (S wave > D wave). Moderate regurgitation is associated with systolic blunting (S wave < D wave) and severe regurgitation with systolic flow reversal. (Practical Perioperative TOE)

Elevated LA pressure can cause systolic blunting in the absence of mitral regurgitation. For eccentric jets, the contralateral pulmonary vein (i.e., on the opposite side from the direction of the jet) should be used to grade the severity of the regurgitation. (Practical Perioperative TOE)

False-negative results (e.g., a normal pulmonary vein flow pattern despite severe regurgitation) occur when the LA is severely enlarged and compliant, so that all the excess volume is contained in the LA without displacement into the pulmonary veins. False-positive results occur when an eccentric jet is directed into a pulmonary vein, thereby causing flow reversal in one vein even when regurgitation is not severe. (Otto, Clinical Echocardiography 6e)

Systolic flow reversal in the pulmonary veins (for MR) or in the hepatic veins (for tricuspid regurgitation) is only useful when sinus rhythm is present because normal venous inflow patterns often are abnormal with other cardiac rhythms, such as atrial fibrillation. (Otto, Clinical Echocardiography 6e)

Pulmonary venous flow - Mild: Systolic dominance; Moderate: Systolic blunting; Severe: Systolic flow reversal. (Oxford Critical Care Echo)

The echocardiographic assessment of MR includes integration of data from 2D/3D imaging of the valve and ventricle as well as Doppler measures of regurgitation severity. Effort should be made to quantify the degree of regurgitation, except in the presence of mild or obviously severe MR. Both the VC width and the PISA method are recommended. Adjunctive parameters help to consolidate about the severity of MR and should be widely used particularly when there is discordance between the quantified degree of MR and the clinical context. (EACVI valvular regurgitation recs)

The severity of valvular regurgitation typically is described using semiquantitative measures as mild, moderate, or severe. The size of the color Doppler jet is not accurate for the evaluation of regurgitant severity. (Otto, Clinical Echocardiography 6e)

Several valve hemodynamic criteria are provided for assessment of MR severity, but not all criteria for each category will be present in each patient. Categorization of MR severity as mild, moderate, or severe depends on data quality and integration of these parameters in conjunction with other clinical evidence. (Otto, Clinical Echocardiography 6e)

There are various ways of assessing the severity of mitral regurgitation. These need to be considered collectively and in context, as they may provide conflicting information. (Practical Perioperative TOE)

EACVI Table 8 cut-offs for grading primary MR severity: VC width <3 mm = mild; intermediate = moderate; ≥7 mm (>8 for biplane) = severe. EROA <20 mm2 = mild; 20-29 / 30-39 mm2 = moderate; ≥40 mm2 = severe. Regurgitant volume <30 mL = mild; 30-44 / 45-59 mL = moderate; ≥60 mL = severe. (EACVI valvular regurgitation recs)

Mitral regurgitation (MR) severity often is indeterminate due to poor image quality, technical issues with data, internal inconsistency among echo findings, or discordance with clinical findings. If imaging is technically difficult, consider TEE or cardiac magnetic resonance (CMR). (Otto, Clinical Echocardiography 6e)

An average VC < 3 mm suggests mild MR while a VC > 8 mm is consistent with severe MR irrespective of aetiology; > 7 mm is suggestive of severe MR when VC is measured in a single plane. (BSE mitral guideline 2021)

Vena contracta (cm): <0.3 = mild; single plane 0.3-0.69, biplane 0.31-0.79 = moderate; single plane ≥0.7, biplane ≥0.8 cm = severe. For 3D vena contracta area, the threshold for severe MR has been defined as > 40 mm2. (BSE mitral guideline 2021)

A VC <3 mm indicates mild MR, whereas a width ≥7 mm defines severe MR. An average value >8 mm on 2D echo has been reported to define severe MR for all aetiologies of MR including functional MR. (EACVI valvular regurgitation recs)

Key point: When feasible, the measurement of VC is recommended to quantify MR. Intermediate VC values (3-7 mm) need confirmation by a more quantitative method, when feasible. (EACVI valvular regurgitation recs)

The width of the vena contracta is the most useful semiquantitative method for grading the severity of mitral regurgitation, and it is recommended by the ASE. The vena contracta is the narrowest point of the jet as it passes through the valve and is in effect the diameter of the effective regurgitant orifice area (EROA). (Practical Perioperative TOE)

The vena contracta should only be estimated in the midesophageal long-axis view to avoid cutting the coaptation line obliquely and potentially overestimating the width of the jet. A vena contracta width of less than 3 mm usually indicates mild mitral regurgitation, and a width equal to 7 mm usually indicates severe mitral regurgitation, although the cutoff has varied between 6 and 8 mm. Vena contracta width is reliable for evaluating central and eccentric jets and is less influenced by loading conditions than jet area; however, it is not validated for multiple jets. (Practical Perioperative TOE)

The vena contracta, the narrowest diameter of the flowstream, reflects the diameter of the regurgitant orifice with the advantages that it is independent of volume flow rate and driving pressure and that it is relatively unaffected by instrument settings. A vena contracta width greater than 0.3 cm indicates that further quantitation of regurgitant severity is needed. (Otto, Clinical Echocardiography 6e)

The PLAX view is typically used for measuring VC width. If it is inadequate, the A4C view is an acceptable alternative. It is recommended to average measurements over at least two to three beats and measurement must be in a plane orthogonal to the line of leaflet coaptation. A VC width of less than 0.3 cm correlates with mild MR, a width of 0.3-0.69 cm is moderate, whereas a width of 0.7 cm or more is an indicator of severe MR. (Oxford Critical Care Echo)

These flow convergence hemispheres are better identified on echo by reducing the CFD velocity at which blood flow aliases (Nyquist limit) to between 20 and 40 cm/s in the direction of the flow. The flow rate through the orifice (mL/s) can be calculated by multiplying the surface area of the hemisphere (2*pi*r^2) by the Nyquist velocity at that point. The orifice area can then be calculated by dividing the flow rate by the velocity of the flow through the valve. (BSE mitral guideline 2021)

EROA (cm2): <0.2 = mild; 0.2-0.39 = moderate; ≥0.4 (may be lower in secondary MR or when EROA is elliptic) = severe. Regurgitant volume (mL): <30 = mild; 31-59 = moderate; ≥60 (may be lower in secondary MR or when EROA is elliptic) = severe. Regurgitant fraction (%): <30% = mild; 30-49% = moderate; >50% = severe. (BSE mitral guideline 2021)

As a ratio of regurgitant flow to total ejected volume, MR is considered severe when the regurgitant volume exceeds half of the total LV SV. Therefore, when expressed as a percentage, a regurgitant fraction (RF) of > 50% indicates severe MR. (BSE mitral guideline 2021)

The area of interest is optimized by lowering imaging depth and reducing the Nyquist limit to ~15-40 cm/s. The radius of the PISA is measured at mid-systole using the first aliasing. Quantitatively, primary MR is considered severe if EROA is ≥40 mm2 and R Vol ≥60 mL. In secondary MR, the thresholds of severity, which are of prognostic value, are 20 mm2 and 30 mL, respectively. (EACVI valvular regurgitation recs)

Key point: When feasible, the PISA method is highly recommended to quantitate the severity of MR. It can be used in both central and eccentric jets. An EROA ≥40 mm2 or an R Vol ≥60 mL indicates severe organic MR. In functional ischaemic MR, an EROA ≥20 mm2 or an R Vol ≥30 mL identifies a subset of patients at an increased risk of cardiovascular events. (EACVI valvular regurgitation recs)

The PISA method of calculating EROA is based on blood flow at the point of color aliasing being the same as flow through the regurgitant orifice. An EROA of 0.4 cm2 indicates severe mitral regurgitation, and a value <0.2 cm2 indicates mild regurgitation. In day-to-day clinical practice in the operating room, if the color Doppler scale is set to 40 cm/sec, a PISA radius of more than 1 cm suggests severe regurgitation. (Practical Perioperative TOE)

Severe mitral regurgitation equates to a regurgitant volume greater than 60 mL/beat and a regurgitant fraction of more than 50%; mild mitral regurgitation equates to a regurgitant volume greater than 30 mL/beat and a regurgitant fraction of more than 30%. Regurgitant fraction (RF) is the regurgitant volume divided by the total forward flow through the MV in diastole. (Practical Perioperative TOE)

Regurgitant flow rate = PISA x Aliasing velocity, with PISA = 2*pi*r^2. The size of the PISA can be maximized to allow more accurate regurgitant flow rate calculations using a zoomed image with the Doppler velocity baseline shifted so that the aliasing velocity is 30 to 40 cm/s in the direction of flow. Definition of severe MR: Regurgitant volume ≥60 mL; Regurgitant fraction ≥50%; Regurgitant orifice area ≥0.4 cm2. (Otto, Clinical Echocardiography 6e)

For primary MR, an EROA of less than 0.2 cm2 and Vr of less than 30 ml correlates with mild disease, an EROA of 0.2-0.39 cm2 and Vr of 30-59 ml is moderate, whereas an EROA of 0.4 cm2 or greater and Vr of 60 ml or more are indicators of severe MR. (Oxford Critical Care Echo)

However, these methods are limited by a number of technical and haemodynamic factors that influence the CFD jet appearance and size. For a given MR severity, unoptimised scan settings will lead to over or underestimation of MR severity. Low driving force (low SBP), increases in LA pressure (LAP), increases in LA size, and jets that adhere to the LA wall due to Coanda effect will all result in varying degrees of underestimation of MR severity. Therefore, although CFD should be used to identify the presence of MR, it should not be used in isolation to quantify severity. (BSE mitral guideline 2021)

Key point: The colour flow area of the regurgitant jet is not recommended to quantify the severity of MR. The colour flow imaging should only be used for detecting MR. A more quantitative approach is required when more than a small central MR jet is observed. (EACVI valvular regurgitation recs)

In the past, regurgitant severity often was graded based on the size of the flow disturbance in the chamber receiving the regurgitant jet on a 1+ (mild) to 4+ (severe) scale. However, this grading system is quite inaccurate, particularly when regurgitation is more than mild, with substantial overlap in jet areas between patients with moderate and severe regurgitation. Color flow 'mapping' also is subject to marked variability due to gain and other instrument settings, as well as physiologic variability. Thus, the area or length of a regurgitant jet is an unreliable indicator of disease severity and should not be used in patient management. (Otto, Clinical Echocardiography 6e)

There are several problems with using jet area to grade mitral regurgitation, and the ASE does not recommend using the technique. Jet area measurements are influenced by loading conditions, ventricular function, atrial size, and Doppler gain settings. Thus, a patient with acute mitral regurgitation and ventricular decompensation will have a smaller jet area for the same degree of mitral regurgitation than a hypertensive patient with chronic mitral regurgitation and a large left atrium. (Practical Perioperative TOE)

Even for a similar severity, acute regurgitation may produce a smaller jet when compared with chronic regurgitation in CFD, due to the lower LV-to-LA pressure gradient. Likewise, due to the Coanda effect, an eccentric jet directed towards the LA wall will appear to be smaller. As a result of these potential sources of errors, CFD is not recommended as the sole method in assessing MR severity. (Oxford Critical Care Echo)

Previous BSE guidance for the assessment of secondary mitral regurgitation recommended that an EROA > 0.2 cm2 and regurgitant volume > 30 mL was consistent with severe MR. The BSE decision to adopt a cut-off of 0.3 cm2 when accompanied by other specific criteria for severe MR recognises: a) that EROA and MR volume by PISA method are underestimated when the mechanism results in an elliptical regurgitant orifice; b) that surgical repair of ischaemic MR with EROA 0.2-0.39 cm2 alone was not associated with improved outcomes. (BSE mitral guideline 2021)

Secondary MR can be considered severe if EROA 0.3-0.39 cm2, regurgitant volume 45-59 mL, or RF 40-49% - AND one of three specific criteria for severe MR: Flail leaflet; VC (single plane ≥0.7 cm, biplane ≥0.8 cm); PISA radius ≥1.0 cm at Nyquist 30-40 cm/s; Central large jet >50% of LA area; Pulmonary vein systolic flow reversal; Enlarged LV with normal function. It is important to highlight that the threshold for diagnosing severe secondary MR is less than for primary MR. (BSE mitral guideline 2021)

Quantitatively, primary MR is considered severe if EROA is ≥40 mm2 and R Vol ≥60 mL. In secondary MR, the thresholds of severity, which are of prognostic value, are 20 mm2 and 30 mL, respectively. These findings could explain why the threshold used to define a severe functional MR is inferior to that used for organic MR. (EACVI valvular regurgitation recs)

Stages of Primary MR, severe (C/D): ERO ≥0.40 cm2; Regurgitant volume ≥60 mL; Regurgitant fraction ≥50%. Stages of Secondary MR, severe (C/D): ERO ≥0.40 cm2; Regurgitant volume ≥60 mL; Regurgitant fraction ≥50%. (Otto, Clinical Echocardiography 6e)

The measurement of the proximal isovelocity surface area by 2D TTE in patients with secondary MR underestimates the true ERO due to the crescentic shape of the proximal convergence. (Otto, Clinical Echocardiography 6e)

EACVI subclassifies the moderate primary regurgitation group into 'mild-to-moderate' (EROA of 20-29 mm2 or an R Vol of 30-44 mL) and 'moderate-to-severe' (EROA of 30-39 mm2 or an R Vol of 45-59 mL). (EACVI valvular regurgitation recs)

Underestimates eccentric jet adhering the atrial wall (Coanda effect) in MR or TR. In case of multiple MR jets, the respective widths of the multiple VC are not additive. (EACVI valvular regurgitation recs)

The PISA method is based on the assumption of hemispheric symmetry of the velocity distribution proximal to the circular regurgitant lesion, which may not hold for eccentric jets, multiple jets, or complex or elliptical regurgitant orifices. (EACVI valvular regurgitation recs)

As a direct measure of effective regurgitant orifice geometry, the assessment of VC is particularly useful for the assessment of eccentric MR jets when other methods of grading severity are less accurate. Since multiple measurements cannot be combined to estimate overall MR severity, the VC estimation is limited when multiple jets are present. (BSE mitral guideline 2021)

In contrast, solid boundaries close to the jet (e.g., in aortic stenosis or eccentric mitral regurgitation) modify its geometry and confine its volume (the Coanda effect is the tendency of a jet to follow a surface, especially a convex surface). Reliance on jet size may then lead to an underestimation of lesion severity. (Practical Perioperative TOE)

Jets may also be affected by interaction with other jets. Dual jet interaction will attenuate the size of the jet of interest if the second jet is in the opposite direction and accentuate it if the second jet is in the same direction. (Practical Perioperative TOE)

The proximal isovelocity surface area approach is less accurate with eccentric jets or when the isovelocity surface area is not hemispherical. In these situations, quantitation of MR by pulsed Doppler volume flow rates is more appropriate. (Otto, Clinical Echocardiography 6e)

Evaluation of regurgitant severity is complex when multiple jets are present along the leaflet coaptation line. The 3D visualization of vena contracta and PISA shows promise for more reliable quantitation of regurgitant severity, but this approach currently is time consuming, requires considerable experience, and is limited by low frame rates. (Otto, Clinical Echocardiography 6e)

Due to the Coanda effect, an eccentric jet directed towards the LA wall will appear to be smaller. The PISA method is also less accurate with eccentric or multiple jets. One important limitation of the use of VC width is the presence of multiple jets and their respective values, which are not additive. (Oxford Critical Care Echo)

The regurgitant orifice geometry in secondary MR is typically elliptical, narrower in the A4C view and wider in the A2C view; the routine use of VC (averaged between A4C and A2C) is encouraged in secondary MR quantification. (BSE mitral guideline 2021)

The elliptical EROA typically associated with secondary MR produces a hemi-ellipsoid PISA geometry. This results in a secondary MR PISA dimension that is greater in the horizontal plane vs the vertical; true regurgitant severity is underestimated when secondary MR assessment is based on PISA height alone. Additionally, severely impaired LV systolic function, often coexistent with secondary MR, often fails to generate a total SV great enough for the standard parameters of MR to reach the threshold for severe. (BSE mitral guideline 2021)

When the shape of the flow convergence zone is not a hemisphere, the PISA method may underestimate the degree of functional MR, particularly when the ratio of long-axis length to short-axis length of the 3D regurgitant orifice is >1.5. In the presence of functional MR, there is a dynamic variation of the regurgitant orifice area with early and late systolic peaks and a mid-systolic decrease. (EACVI valvular regurgitation recs)

Due to the non-hemispheric nature of secondary (functional) MR, assessment by PISA and its correlation to severity is often confounded. The PISA method is also less accurate with eccentric or multiple jets. (Oxford Critical Care Echo)

Mitral regurgitation, particularly if secondary to ischemia, altered geometry of the left ventricle, or SAM, is particularly sensitive to loading conditions, so severity is better assessed on the preoperative echocardiogram rather than with TEE under the effects of anesthesia or sedation. Sometimes severe dynamic mitral regurgitation is only recognized during stress echocardiography. (Practical Perioperative TOE)

In patients with regurgitation only in late systole, rather than holosystolic, this approach overestimates regurgitant severity. In some cases, it is difficult to determine whether MR is the cause or consequence of ventricular dilation and systolic dysfunction. (Otto, Clinical Echocardiography 6e)

In the setting of hypotension loading conditions (systemic blood pressure, administration of vasoactive medications and presence of an intra-aortic balloon pump) will influence the appearance of a regurgitant jet on colour-flow and continuous-wave Doppler. (Oxford Critical Care Echo)

In those with primary severe MR, an LVEF <60% is suggestive of impaired systolic function. (BSE mitral guideline 2021)

Echocardiographic indications for MV surgery - Left ventricle (primary MR): LV dilatation by Simpson's biplane volume; LVESD ≥40 mm; LVEF ≤60%. Systolic pulmonary artery pressure: SPAP >50 mmHg. Left atrium: Simpson's biplane MOD ≥60 mL/m2 (in SR). Valve anatomy: Flail leaflet. (BSE mitral guideline 2021)

Once MR becomes severe, the onset of symptoms or signs of LV impairment is a class I indication for surgical intervention (repair or replacement) to improve outcome. (BSE mitral guideline 2021)

Current data suggest that, in adults with severe primary MR, evidence of progressive ventricular dilation, an end-systolic dimension 40 mm or greater, or any reduction in LV systolic function (ejection fraction 60% or less) should prompt consideration of surgical intervention, regardless of the symptomatic status of the patient, to prevent irreversible ventricular dysfunction postoperatively. (Otto, Clinical Echocardiography 6e)

Stages of Primary MR, Stage C: C1: LVEF >60% and LVESD <40 mm; C2: LVEF ≤60% and LVESD ≥40 mm. (Otto, Clinical Echocardiography 6e)

An important clinical feature of chronic LV volume overload is that an irreversible decrease in systolic function can occur in the absence of symptoms. In fact, an irreversible decrease in contractility can occur despite a normal ejection fraction because of the altered loading conditions of the ventricle when regurgitation is present. (Otto, Clinical Echocardiography 6e)

The quantitative assessment of myocardial function (systolic myocardial velocities, strain, strain rate) is reasonable, particularly in asymptomatic patients with severe primary MR and borderline values in terms of LV ejection fraction (60-65%) or LV end-systolic diameter (close to 40 mm or 22 mm/m2). (EACVI valvular regurgitation recs)

Normal or mildly reduced LV systolic contractility (ejection fraction <55% and an end-systolic short-axis diameter >4 to 4.5 cm) suggests significant LV impairment. (Practical Perioperative TOE)

The assessment of LA size is an important element in the investigation of mitral regurgitation. LA dilatation secondary to volume overload is an expected finding in those with chronic severe MR. Normal LA volume, therefore, rules out chronic severe MR with near certainty. Estimation of LA volume by Simpson's biplane method is recommended. (BSE mitral guideline 2021)

Increases in left atrial pressure secondary to severe mitral regurgitation translate to increased pulmonary artery capillary wedge pressure and, therefore, raised systolic pulmonary artery pressure (SPAP). Estimating SPAP by echocardiography is important in patients with severe MR to ensure the appropriate timing of intervention. (BSE mitral guideline 2021)

Key point: When MR is more than mild MR, providing the LV diameters, volumes, and ejection fraction as well as the LA dimensions (preferably LA volume) and the pulmonary arterial systolic pressure in the final echocardiographic report is mandatory. (EACVI valvular regurgitation recs)

Stages of Primary MR - Stage C/D hemodynamic consequences: Moderate or severe LA enlargement; LV enlargement; Pulmonary hypertension may be present at rest or with exercise (Stage C) / present (Stage D). (Otto, Clinical Echocardiography 6e)

Echocardiographic evaluation of pulmonary artery pressures is a basic component of the exam in patients with MR. (Otto, Clinical Echocardiography 6e)

Signs of pulmonary hypertension, consistent with LV decompensation. These include a tricuspid regurgitation jet velocity greater than 3 m/sec and enlargement of the right ventricle and the right atrium. (Practical Perioperative TOE)

Chronically elevated LA pressure leads to remodelling of pulmonary vasculature and an increase in pulmonary vascular resistance, thus giving rise to chronic pulmonary hypertension and right ventricular dysfunction. (Oxford Critical Care Echo)

Where echo windows are limited, or further clarification in aetiology, mechanism and reparability of the valve lesion is needed, TOE offers high-resolution imaging. When interventions such as MV repair or percutaneous mitral commissurotomy are contemplated, TOE provides essential morphological data to guide patient selection. (BSE mitral guideline 2021)

In mitral valve prolapse, the likelihood of repair decreases as valve lesion complexity increases. Although surgical repair has demonstrated good long-term durability with more straightforward lesions such as isolated P2 prolapse, increasingly complex lesions (ranging from P1 or P3 involvement, isolated anterior leaflet prolapse, commissural involvement and bileaflet disease) requires greater surgical expertise and may be less durable. (BSE mitral guideline 2021)

In primary MR, some predictors of unsuccessful repair have been reported: the presence of a large central regurgitant jet, severe annular dilatation (>50 mm), involvement of ≥3 scallops especially if the anterior leaflet is involved, and extensive valve calcification. (EACVI valvular regurgitation recs)

In secondary ischaemic MR, patients with a mitral diastolic annulus diameter ≥37 mm, a systolic tenting area ≥1.6 cm2, and a severe functional ischaemic MR could have a 50% probability of recurrence of regurgitation after mitral valve repair. (EACVI valvular regurgitation recs)

Isolated MV repair is most commonly performed for myxomatous degeneration. An isolated flail segment involving P2 is the most favorable lesion for successful repair. The rate of successful repair is lower for lesions involving the anterior leaflet (either isolated anterior leaflet or bileaflet lesions) or in the presence of calcification of the annulus or leaflets. (Practical Perioperative TOE)

The risk of SAM is higher if the ratio of the lengths of the anterior (AML) to the posterior (PML) mitral leaflets (i.e., AML/PML) is below 1 than if it is above 3; it is also higher if the C-sept distance is shorter than 2.5 cm than if it is longer than 3.0 cm. (Practical Perioperative TOE)

Once the decision has been made that relief of MR is needed, the echocardiographic images are invaluable in considering whether mitral valve repair or reconstruction is possible or whether valve anatomy is amenable to a transcatheter procedure. 3D TEE imaging is essential for complete visualization of valve anatomy and measurements specific to each procedure. (Otto, Clinical Echocardiography 6e)

Typically, posterior leaflet prolapse and annular dilation are most amenable to surgical repair, whereas more complex or extensive disease requires more complex procedures with a lower likelihood of successful repair. The use of intraprocedural TEE is associated with a higher rate of successful mitral valve repair at both academic and community medical centers. (Otto, Clinical Echocardiography 6e)

Should TTE imaging prove to be inadequate, TOE may be required to complement the assessment. (Oxford Critical Care Echo)

Because of rapid pressure equalisation, a triangular waveform with peaking in early systole is suggestive of very severe or torrential, often acute MR. Given the rapid onset, acute severe MR may be associated with little or no chamber dilation or adverse remodelling. (BSE mitral guideline 2021)

In acute MR, even centrally directed jets may be misleadingly small. In acute severe MR, the pulmonary pressures are usually elevated while the LV size is still often normal. A modest regurgitant volume reflects severe MR when it develops acutely into a small, non-compliant LA and it may cause pulmonary congestion and systemic hypotension. (EACVI valvular regurgitation recs)

With acute MR, an increase in LA pressure during late systole - a v-wave - usually is present because of a steep pressure-volume relationship of the nondilated LA. The corresponding Doppler velocity curve shows a high initial velocity with a more rapid fall in velocity in mid-systole to late systole. However, vena contracta width remains accurate in the setting of acute regurgitation, whereas jet area is misleading. (Otto, Clinical Echocardiography 6e)

In acute MR the LA and LV dimensions are usually normal or mildly increased, unless there is also intrinsic LV systolic or diastolic dysfunction. Colour Doppler can underestimate severity as the regurgitant jet may not fill the entire LA. This is due to a rapid rise in LA pressure which causes regurgitant flow to cease. A vena contracta width more than 7 mm indicates severe MR. (Oxford Critical Care Echo)

The presence of severe MR with a normal size or hyperdynamic LV should raise the suspicion of acute severe MR. Quantitative measures of MR severity that are useful in chronic regurgitation are less accurate in acute MR, particularly in association with tachycardia. Continuous-wave Doppler across the MV will demonstrate increased forward velocities (>1 m/s) and a short truncated regurgitant jet. (Oxford Critical Care Echo)

Echocardiography demonstrates torrential mitral regurgitation. The ruptured head of the papillary muscle can usually be seen flicking in and out of the left atrium. The cardiac chambers are often small. Pulmonary arterial pressure is elevated. (Practical Perioperative TOE)

Acute severe MR can result from either primary or secondary causes. Primary causes include leaflet perforation or destruction secondary to endocarditis, leaflet prolapse secondary to chordal rupture (because of either myxomatous valve degeneration or trauma) and papillary muscle rupture due to myocardial ischaemia. Secondary acute MR is usually caused by ischaemia of the infero-lateral wall leading to regional wall motion abnormality with papillary muscle dysfunction and restricted MV closure (tethering) of the posterior leaflet. (BSE mitral guideline 2021)

A flail leaflet, a ruptured papillary muscle or a large coaptation defect is specific for severe MR. (EACVI valvular regurgitation recs)

Papillary muscle rupture can occur as a complication of acute myocardial infarction. If the entire papillary muscle is disconnected from the underlying LV wall, few patients will survive because of acute, severe MR. Echocardiographic evaluation in those who do survive shows a mass (the ruptured papillary muscle) attached to flail segments of anterior and posterior leaflets (because each papillary muscle attaches to both leaflets). The ruptured papillary muscle head is seen in the LA in systole and in the LV in diastole. (Otto, Clinical Echocardiography 6e)

Partial rupture of a papillary muscle, defined as rupture of one of several 'heads' or as partial disconnection of the base of the papillary muscle, is seen more often than complete rupture because patients are more likely to survive long enough to undergo diagnostic evaluation. Acute MR due to chordal rupture typically manifests as acute pulmonary edema. (Otto, Clinical Echocardiography 6e)

Occasionally, as a complication of myocardial infarction, papillary muscle rupture occurs. This most frequently affects the posteromedial muscle and results in torrential bileaflet regurgitation involving A3/P3 and A2/P2. The posteromedial papillary muscle is most frequently affected due to its sole blood supply by branches of the right coronary artery (in contrast, the anterolateral papillary muscle has dual blood supply from branches of the left anterior descending and circumflex coronary arteries). LV size is usually normal, and a (inferior) SWMA may be identified. (Practical Perioperative TOE)

Papillary muscle rupture occurs as a complication of acute myocardial infarction. Lesions can range from incomplete leaflet coaptation with mild MR to frank perforation and chordae tendineae rupture with severe regurgitation. The anterolateral muscle typically has a dual blood supply, while the posteromedial muscle is supplied from only the posterior descending artery - thus the posteromedial muscle is more susceptible to ischaemic changes. (Oxford Critical Care Echo)

Although it occurs infrequently, it is usually dramatic in presentation in causing severe mitral regurgitation. Rapid diagnosis is important for referral for urgent mitral valve replacement with echo being the first-line diagnostic modality. (Oxford Critical Care Echo)

Since the onset of MR is acute, the sudden increase in volume results in a rapid and significant increase in LAP with no immediate change in the chamber size (non-compliant). The significant increase in LAP will result in a rapid rise in pulmonary venous pressure, may result in acute pulmonary oedema and may progress to cardiogenic shock. (BSE mitral guideline 2021)

Blood pressure and heart rate are therefore essential considerations when investigating MR, and should always be recorded and their effect considered. (BSE mitral guideline 2021)

Acute MR results in a reduction of forward stroke volume through the aortic valve, due to regurgitation of a substantial part of the stroke volume (regurgitant fraction) back into the LA. The acute regurgitation increases volume into a normally compliant LA, resulting in a marked increase in left atrial pressure. Compensatory tachycardia may preserve cardiac output initially, but eventually hypotension, organ failure, and other evidence of cardiogenic shock will develop. (Oxford Critical Care Echo)

Papillary muscle rupture is the aetiology most often associated with severe hypotension and mandates TOE assessment if suspected. Treatment requires urgent intra-aortic balloon pump (IABP) insertion and emergency MV surgery. (Oxford Critical Care Echo)

Acute MR - Indications for intervention: Urgent surgical intervention usually is needed, except for some coronary disease cases where revascularization may decrease MR severity. Options for intervention: Treat underlying disease process (e.g., coronary disease, endocarditis); Stabilize in ICU with IABP; Urgent surgical valve repair or replacement. (Otto, Clinical Echocardiography 6e)

The severity of mitral regurgitation - except that due to dynamic LVOT obstruction - is increased by volume overload and high LV afterload, and these factors may exacerbate low cardiac output and high LA pressure in this circumstance. (Practical Perioperative TOE)

In these situations, integration of data derived from other haemodynamic adjuncts (i.e. pulmonary artery catheter) in addition to echocardiography findings can provide an integrative approach to determine the severity of MR. (Oxford Critical Care Echo)

It is essential to be aware of the potential haemodynamic changes in the fluid depleted and sedated patient, and the consequences on mitral valve assessment. This is particularly relevant in MR where its severity can be underestimated. Blood pressure and heart rate are therefore essential considerations when investigating MR, and should always be recorded and their effect considered. (BSE mitral guideline 2021)

Transoesophageal echocardiography is very useful for assessing severe acute mitral and aortic regurgitation. Diagnosis of acute prosthetic valve regurgitation mandates TOE. (Oxford Critical Care Echo)

Transoesophageal echocardiography allows close evaluation of valve anatomy (e.g. papillary muscle rupture) and the pulmonary veins to look for systolic flow reversal (indicating severe MR). (Oxford Critical Care Echo)

A hyperdynamic LV with end systolic cavity obliteration has other causes apart from hypovolaemia. Severe acute mitral regurgitation, an acute ventricular septal defect, left ventricular hypertrophy especially in the presence of inotrope medication, may also cause this appearance. (Oxford Critical Care Echo)

When transthoracic echocardiographic images are not diagnostic for the evaluation of aortic or mitral valve anatomy and the etiology of regurgitation, transesophageal echocardiographic (TEE) imaging is appropriate if needed for clinical decision making. (Otto, Clinical Echocardiography 6e)

Acute valvular regurgitation often is initially missed because the clinical presentation mimics an acute pulmonary process. When TTE data are suggestive but not diagnostic, TEE imaging is appropriate. Management often includes urgent surgical intervention. (Otto, Clinical Echocardiography 6e)

Triage status: all verbatim excerpts gathered from the BSE mitral guideline 2021, EACVI valvular regurgitation recommendations, Practical Perioperative TOE, Otto Clinical Echocardiography 6e and Oxford Critical Care Echo were each assignable to a single best-matching Q&A and have been sorted there; no leftover/orphan excerpts remain at this pass.

To revisit later — borderline numeric divergences flagged across sources: VC severe threshold BSE >8 mm biplane / >7 mm single-plane vs EACVI ≥7 mm (>8 mm biplane average); secondary-MR EROA/RVol severe thresholds differ by society (BSE EROA 0.3-0.39 cm2 plus supportive criteria; EACVI EROA ≥20 mm2 / RVol ≥30 mL; Otto stages use ≥0.4 cm2 / ≥60 mL). These belong with qa-mr-vena-contracta and qa-mr-primary-vs-secondary-thresholds if a consolidated comparison line is wanted. (cross-source)