Colour Doppler echocardiogram in rheumatic heart disease (RHD), mitral regurgitation (MR). The mosaic coloured MR jet is outlined in the left atrium (LA). Ao: aorta; LV: left ventricle; RV: right ventricle. The left frame shows the apical five chamber view in diastole, while the right frame shows the apical four chamber view in systole. The apical five chamber view also shows an aortic regurgitation jet which merges with the jet of mitral stenosis in the left ventricle. Mitral leaflets appear thickened, though the finer morphological details of the mitral and aortic valves are not clear in these colour flow mapping images. MR severity can be assessed by comparing the MR jet area with that of the left atrium as well as by observing the extend of penetration of the jet into the left atrium. The larger the comparitive jet area and more distant the penetration of the jet, higher the severity of the mitral regurgitation. A disadvantage for comparing the area of the jet with that of the left atrium is in the presence of a grossly dilated left atrium. Similarly, the depth of jet penetration may vary depending on the eccentricity of the jet. This is also applicable to jet area, with eccentric jet appearing smaller in area.

Colour Doppler echocardiogram in RHD, MR – annotated

Tricuspid regurgitation jet on continuous wave Doppler

Continous wave (CW) Doppler interrogation from the apical four chamber view for echocardiography across the tricuspid valve picked up this jet with a velocity of 302 cm/s and a peak gradient (PG) of 37 mm Hg. If the right atrial pressure is taken as 10 mm Hg (as it is conventionally done), the estimated right ventricular systolic pressure would be 47 mm Hg. If the right atrial pressure is elevated as evidenced by a raised jugular venous pressure (JVP), appropriate corrections may be made for the measured JVP. The incomplete envelope in certain cycles is because the heart moves with respect to the Doppler cursor. Changes could also be due to changes in the volume of regurgitation in different phases of respiration. Tricuspid regurgitation increases as the systemic venous return increases in inspiration. Tricuspid regurgitation (TR) is often secondary to right ventricular / pulmonary hypertension as in this case. Sometimes a low pressure TR can occur due to the inherent disease of the tricuspid valve as in carcinoid syndrome or Ebstein’s anomaly. In rheumatic heart disease the mechanism can be a combination of valvular abnormality as well as elevated right ventricular pressures due to pulmonary hypertension secondary to left sided valvlular lesions. Severe organic tricuspid regurgitation may require tricuspid annuloplasty.

Echocardiogram after repair of Tetralogy of Fallot (TOF) from the parasternal long axis (PLAX) view showing the hyperechoeic region of the patch which was used to close the ventricular septal defect. The aortic over-ride is no more present. Ao: aorta; RV: right ventricle; LV: left ventricle; LA: left atrium.

Post TOF repair M-mode echo

M-mode echocardiogram after repair of TOF showing the abnormal septal motion which is biphasic and not in line with the movement of the posterior wall which shows regular contractions and relaxations.

Mild PR after TOF repair

The signals above the baseline represent the reverse flow from the pulmonary artery into the right ventricular outflow tract in diastole due to pulmonary regurgitation (PR). The signal is incomplete partly because of the lack of complete allignment of the Doppler beam to the flow and partly because the regurgitation is only mild. In most cases of repaired TOF, there will be significant PR. In some cases it may be even severe enough to produce late right ventricular dysfunction. Here it is not that severe.

Pumonary valve M-mode echocardiogram after TOF repair

M-mode echocardiogram of the pulmonary valve after TOF repair, showing almost normal pattern with an A wave just before the onset of systole. The diastolic portion of the movement is better seen than the systolic portion. The pulmonary valve echocardiogram shows a prominent (deep) A wave in pulmonary stenosis and a flat A wave in pulmonary hypertension.

Apical five chamber view after TOF repair

Apical five chamber (5C) view after TOF repair, showing the patch in the subaortic region where the VSD (ventricular septal defect) was closed. ATL: anterior tricuspid leaflet.

Post TOF repair TR

Tricuspid regurgitation jet (TR) seen after TOF repair, with a gradient of 32 mm Hg, indicating mildly elevated right ventricular pressures. The right ventricular pressure prior to repair would have been equal to systemic pressure. TR jet is depicted below the baseline because the flow is away from the transducer kept at the apex.

Subcostal view showing intact atrial septum

Colour Doppler echocardiographic video after repair of Tetralogy of Fallot. The patch closing the ventricular septal defect is seen as a hyperechoeic region below the aortic valve, both in the parasternal long axis view and the apical five chamber view. Colour flow mapping shows that there is no residual VSD flow across the septum in that region. Short axis imaging shows mild PR and apical four chamber imaging shows mild TR. Subcostal view demonstrates the intact inter atrial septum.

A defect in the atrioventricular septum was described by Gerbode F et al in 5 operated cases in 1958 [Gerbode F., Hultgren H., Melrose D., Osborn J. Syndrome of left ventricular-right atrial shunt: successful surgical repair of defect in five cases, with observation of bradycardia on closure. Ann Surg 1958;148(3):433-446]. Anatomically this defect is possible because the septal attachment of the tricuspid valve is distal to that of the mitral valve so that there is a small region of the septum which is between the left ventricle and the right atrium, known as the atrioventricular septum. Usually the defect is congenital. But cases are on record in which the septal defect was acquired due to infective endocarditis. It is mentioned that congenital variety of defect occurs inferior to the tricuspid valve while the aquired variety is superior to the valve.

LV – RA shunt in perimembranous VSD across STL fenestration

The still image shows both the jet from the left ventricle to the right ventricle across the perimembranous VSD and the jet from left ventricle to right atrium across the VSD, through the fenestration in the septal tricuspid leaflet into the right atrium.

Echocardiographic video (color Doppler) showing LV – RA shunt through VSD, across the STL

Initial view shows the mosaic jet from left ventricle to right ventricle across the subaortic VSD as well as another jet traversing the defect in the septal tricuspid leaflet into the right atrium. This second jet resembles a tricuspid regurgitation jet. Second view is the parasternal short axis view of flow from the left ventricule to right ventricle, in the classical location of a perimembranous VSD.

During echocardiographic evaluation, the jet of the Gerbode VSD is likely to be mistaken as a tricuspid regurgitation jet. This will cause misinterpretation as severe pulmonary hypertension while in fact the right ventricular pressures may be low. This can be identified by carefully visualizing the jet origin on colour Doppler. The structural defect can also be seen by careful two dimensional imaging. Pulmonary arterial pressure can be counter checked by using the pulmonary regurgitation jet.

Mitral valve is the most commonly involved valve in rheumatic heart disease. According to Paul Wood, the involvement of the valves in rheumatic heart disease is depending on the hemodynamic load on the valve. The mitral valve faces the maximum load as it withstands the contractile force of the left ventricle during systole. The next highest load is on the aortic valve, the load on which is the aortic diastolic pressure.

Rheumatic mitral valve involvement is characterised by commissural fusion. This causes the valve leaflets to move together in the same direction during diastole. Normally the anterior mitral leaflet (AML) moves anteriorly during the opening motion in diastole and the posterior leaflet moves posteriorly. Due to commissural fusion the posterior leaflet moves anteriorly along with the anterior mitral leaflet in diastole. This is a paradoxical movement of the posterior mitral leaflet (PML). The movement of the anterior mitral leaflet is also restricted, producing a doming or hockey stick like appearance in diastole. The diastolic separation between the leaflets is also reduced, obstructing the forward flow across the valve. In cross sectional imaging the mitral valve has a fish mouth appearance, with thickening of both leaflets and fusion of anterolateral and posteromedial commissures.

The image above illustrates all the feature in the parasternal long axis view (PLAX) like doming of AML, anterior displacement of the PML and reduced leaflet separation in diastole. The dilated left atrium (LA) secondary to the mitral valve obstruction is also evident. The circular echolucency  behind the left atrium is the cross section of the descending aorta. In live imaging it will seen as pulsatile, increasing dimensions in systole and reducing in diastole. Ascending aorta (Ao) is seen anterior to the left atrium and is of normal size. Aortic valve is in a closed position and is seen only faintly as it is not thickened. Left ventricular cavity is seen distal to the mitral valve (LV) and the right ventricle (RV) is seen above, with the interventricular septum in between (not marked). The apex of the triangular image is the position of the transducer, which has been kept in the left parasternal region, on the anterior chest wall, just anterior to the right ventricle.

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Colour Doppler of mitral flow on echocardiography with colour flow mapping (CFM) from the apical four chamber view. The left frame is in diastole when the mitral valve is open and there is a forward flow from the left atrium into the left ventricle. The flow is predominantly reddish, though there is an area of variance in the middle with yellowish and greenish colour. This indicates that the flow velocity in that region is above the Nyquist limit, which in this case is 61 cm/s as seen from the colour bar at the top right corner. The right frame shows the mitral valve in a closed position indicating systole and there is a small regurgitant jet of high velocity which is bluish mosaic coloured. Bluish colour indicates a reverse flow away from the transducer. The flow is from the left ventricle to the left atrium. The jet area is quite small compared to that of the left atrium, indicating that the volume of regurgitation is low. There is no significant dilatation of the left atrium or the left ventricle as the regurgitation is not sufficient to produce volume overloading of the left sided chambers.

Systolic and diastolic frames from apical 4C view on echocardiography

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Systolic and diastolic frames from apical 4C view on echocardiography seen on the same screen.The left image is in diastole as the mitral valve is seen to be open (only anterior mitral leaflet is visible as jutting into the left ventricle). In the right image, the mitral valve is seen in closed position, separating the left ventricle above and the left atrium below. Part of the septal tricuspid leaflet is also seen in the closed position. See that there is a short separation between the septal attachements of the mitral and tricuspid leaflets. This region is known as the atrioventricular septum. Atrioventricular septum is absent in endocardial cushion defects and the two septaly attached leaflets will be at the same level. A defect in the atrioventricular septum is called as a Gerbode ventricular septal defect (Gerbode VSD). In Ebstein’s anomaly the separation between the mitral and tricupsid attachments are increased so that the septal tricuspid leaflet is displaced distally. The green tracing at the bottom of the image is the ECG for identifying the frames as systolic and diastolic, when there is a doubt. Usually systolic and diastolic frames are captured for measuring the ventricular volume and ejection fraction by the area length / Simpson’s method.

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Tissue Doppler Imaging (TDI) measures the velocity of myocardial motion using Doppler principles. While the usual Doppler echocardiography measures the velocity of blood flow using the Doppler signals from the fast moving blood cells, which are of low amplitude, tissue Doppler measures low velocity, high amplitude signals from the myocardial tissue motion. Tissue Doppler is not able to differentiate between passive motion and active motion due to fibre shortening. But the newer technology of strain imaging is able to do so. Colour coded tissue Doppler imaging is sometimes called colour kinesis. Pulsed wave TDI is useful to measure myocardial velocities in the long axis as the movement is parallel to the Doppler beam. The mitral annular TDI has three waves: Sa, systolic myocardial velocity; Ea, early diastolic myocardial velocity and Aa, myocardial velocity during atrial contraction. While imaging from the apical view, systolic velocities are positive and diastolic velocities are negative. Systolic velocity at the lateral mitral annulus correlates with the longitudinal systolic function of the left ventricle. Diastolic velocities depend on ventricular diastolic function. TDI assessment of diastolic function is load independent compared to the conventional measurement using mitral inflow velocities which are highly sensitive to preload.

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Eccentric jet of aortic regurgitation cursing along the posterior margin of the left ventricular outflow tract (anterior mitral leaflet). Estimation of severity of eccentric jets may be erroneous as often the severity tends to be under estimated in case of eccentric jets. AR: aortic regurgitation; LA: left atrium; LV: left ventricle; RV: right ventricle. The frame to the left is a systolic frame and the right one is a diastolic frame. The systolic frame shows the mitral valve in the closed position while the diastolic frame shows it in the open position. The anterior mitral leaflet shows a reverse doming as the aortic regurgitation jet strikes it. Systolic frame also shows a trivial mitral regurgitation into the left atrium, just behind the mitral valve as a bluish mosaic jet.