Cardiophile MD » Echocardiography

AV interval optimization in CRT

Johnson Francis — Fri, 27 Jan 2012 05:51:34 +0000

The aim of AV (atrioventricular) interval optimization in CRT (cardiac resynchronization therapy or biventricular pacing) is to prevent too early or too late atrial contraction. Too late an atrial contraction will cause it to overlap with ventricular systole so that atrial contraction will occur against a closed AV valve. This will lead to a sudden elevation of atrial and pulmonary as well as systemic venous pressure. Echocardiographic methods to optimize AV delay are Ritter’s method and Ishikawa’s method. In Ritter’s method, long AV delay is calculated when there is partial fusion of E and A waves on mitral Doppler and short AV delay is calculated when A wave truncation occurs due to ventricular contraction before completion of A wave. From these two values, the optimal AV delay is calculated using the Ritter’s formula.

Ishikawa’s method is used when there is significant diastolic mitral regurgitation. Long AV delay is chosen so that it results in diastolic mitral regurgitation or diastasis until isovolumetric contraction, which is the time at which systolic mitral regurgitation starts. It may be noted that there is no true isovolumetric phase when there is systolic mitral regurgitation as mitral valve starts leaking in the potential isovolumetric phase and reduces the ventricular volume. The duration of diastolic mitral regurgitation is subtracted from the long AV delay to get the optimal AV delay.

Left ventricular cardiac tamponade

Johnson Francis — Mon, 26 Dec 2011 14:12:13 +0000

Usual manifestation of cardiac tamponade on echocardiography is diastolic collapse of right atrium and right ventricle. This is because right sided chambers can be compressed with much lower intrapericardial pressures than the thicker left ventricle. Isolated left ventricular cardiac tamponade can occur postoperatively due to loculated collections posterior to the left ventricle. Echocardiogram will show left ventricular diastolic compression without associated right ventricular or right atrial collapse. Another situation in which isolated left ventricular diastolic collapse occurring with circumferential pericardial effusion alson with cor pulmonale has been reported [Gollapudi RR et al. Left ventricular cardiac tamponade in the setting of cor pulmonale and circumferential pericardial effusion. Case report and review of the literature. Cardiol Rev. 2005;13:214-7]. In this case, right ventricular collapse was possibly prevented by the severe pulmonary hypertension and right ventricular hypertrophy. The disorder was noted in a case of connective tissue disorder with cor pulmonale. Left ventricular diastolic collapse can significantly affect left ventricular filling and cardiac output. The classic finding of cardiac tamponade – pulsus paradoxus, may be masked in left ventricular tamponade. An interesting case of left ventricular diastolic collapse and regional tamponade following cardiac surgery due to a large left pleural effusion, without any pericardial effusion has also been described [Bilku RS et al. Left ventricular diastolic collapse and late regional cardiac tamponade postcardiac surgery caused by large left pleural effusion. J Am Soc Echocardiogr. 2008;21:978.e9-11]. In this case, tamponade occurred more than two weeks after the surgery, which was an elective aortic valve replacement.

Intracardiac echocardiography (ICE)

Johnson Francis — Mon, 28 Nov 2011 16:49:06 +0000

Intracardiac echocardiography allows excellent resolution images because high frequency transduceres can be used in close proximity toe the structures being images. High frequency signals, though providing high resolution, have poor depth penetration. But since intracardiac echocardiography signals need not travel large distances as the structures are quite near to the transducer. Superb anatomical details may be obtained to help in the diagnosis of complex cardiac abnormalities. The ICE transducer is enclosed in an acoustic housing at the distal end of the catheter used for introducing it into the cardiac chambers. Just as in intravascular ultrasound (IVUS), 360 degree imaging is possible. The images are cross-sectional with the catheter in the centre, just as in IVUS. It is also possible to deflect the catheter tips in certain models which allow easy manipulation within cardiac chambers. It has Doppler facility for evaluating blood flow velocity as well as tissue velocity. ICE is being increasingly used to guide radiofrequency ablations and septal punctures for electrophysiology work. It is useful in evaluating aortic aneurysms and stent grafts. ICE has also been used recently to aid complex surgical procedures for congenital heart disease and structural heart diseases.

Carpentier nomenclature of mitral leaflet scallops

Johnson Francis — Sat, 29 Oct 2011 06:55:29 +0000

Carpentier nomenclature of mitral leaflet scallops is important in assessing the mitral leaflets while planning echo. The scallops can be identified well by trans esophageal echocardiography, preferably in three dimensional mode. Two indentations in the posterior leaflet divides it into three independently mobile scallops named P1, P2 and P3. Anterior leaflet is nonindented, by but has been divided into three corresponding virtual subdivisions known as A1, A2 and A3. Posterior leaflets have a quadrangular shape while the anterior leaflets have semicircular shape. These can be visualized well by a magnified three dimensional echocardiograpic (3DE) image. Systolic billowing of the mitral leaflets into the left atrium is rather uniform with an exception in the P1 and P2 region. P1 has a single focus of regional heterogeneity in the curvature while P2 has two large foci of heterogeneity in curvature. This may be the reason why these two segments have a higher propensity for prolapse and becoming flail.

Tachycardia mediated atrial cardiomyopathy and left atrial appendage velocity

Johnson Francis — Sun, 23 Oct 2011 15:36:11 +0000

Tachycardia mediated atrial cardiomyopathy is the term sometimes used to denote atrial mechanical stunning after reversion of persistent atrial arrhythmias like atrial fibrillation or atrial flutter to sinus rhythm. This can persist for a variable period of time and can be documented by assessing left atrial appendage emptying velocity by Doppler studies. The intrinsic late diastolic contraction of the left atrial appendage produces the so-called “a”-wave, which is seen as a positive flow (directed toward the transducer) on trans esophageal echocardiography and appears just after the P wave on the electrocardiogram. This wave occurs simultaneously with the A wave of mitral inflow. There is no correlation between the velocities of the left atrial appendage a wave and the mitral inflow A wave. Left atrial appendage a wave is the largest wave in sinus rhythm with normal left atrial appendage function. It correlates with the ejection fraction of the left atrial appendage. In post cardioversion atrial stunning (tachycardia mediated atrial cardiomyopathy) the e wave due to passive left atrial appendage emptying becomes preponderant. This e wave is caused by a combination of factors which include passive compression induced by left ventricular relaxation, passive suction effect due to opening of the mitral valve and the rapid emptying of the left atrium in early diastole.

Aortic arch on echocardiogram

Johnson Francis — Mon, 15 Aug 2011 14:25:09 +0000

Aortic arch on supersternal echocardiographic view

Aortic arch is visualized by placing the transducer in the suprasternal view. Ascending aorta (Asc Ao), aortic arch (Ao Arch) and descending aorta (Desc Ao) are seen in this view. This view can be used to visualize coarctation of aorta, descending aortic flow reversal in severe aortic regurgitation and to assess the aortic valve gradient from the supra sternal view. It is useful in congenital heart disease to assess the relation between aorta and pulmonary artery as the aorta is always superior in this view.

Ventricular septal defect – perimembranous

Johnson Francis — Sun, 24 Jul 2011 17:40:02 +0000

Perimembraneous ventricular septal defect (VSD)

Medium sized ventricular septal defect in peri-membranous location seen from the apical five chamber view. RV: right ventricle; LV: left ventricle; VSD: ventricular septal defect; Ao: aorta; RA: right atrium; LA: left atrium; IVS: interventricular septum. There is aneurysm of the inteverventricular septum covering the VSD, leaving a small gap. The VSD jet passes through this small defect which is restrictive (below).

VSD Jet on continuous wave Doppler

VSD jet documented by continuous wave Doppler interrogation, showing an interventricular gradient of 61.5 mm Hg, which suggests that the defect is restrictive. Actual gradient may be even more as this jet has an incomplete envelope.

Vegetation on tricuspid valve – echocardiographic image

Johnson Francis — Sun, 24 Jul 2011 17:34:48 +0000

Vegetation on tricuspid valve

Vegetation on tricuspid valve seen on echocardiography from a modified apical four chamber view. LV: left ventricle; LA: left atrium; RV: right ventricle; RA: right atrium. In live echo imaging, the vegetation will show an motion pattern independant of the movement of the tricuspid leaflet. Tricuspid valve endocarditis with vegetation is seen in intravenous users or occasionally in those with a central venous catheter for a long period.

Flail septal leaflet of tricuspid valve

Repeat echo at a later date after antibiotic treatment showing regression of vegetation and a flail septal tricuspid leaflet pointing towards the right atrium. Flail leaflet is a result of rupture of the chordae tendinae and causes tricuspid regurgitation.

Tricuspid regurgitation jet

Severe tricuspid regurgitation seen as a bluish mosaic (multi-clour) jet from right ventricle to right atrium in systole. The mitral valve can be seen in the closed position between left ventricle and left atrium indicating that it is a systolic frame.

Tricuspid regurgitation severe and mild

Johnson Francis — Sun, 24 Jul 2011 17:29:08 +0000

TR Colour Jet

Colour Doppler echocardiogram in apical four chamber view (slightly tilted) showing tricuspid regurgitation jet. Right ventricle (RV) is seen dilated and hypertrophied, with a prominent moderator band (just below the RV label). Right atrium (RA) is also dilated, both due to severe pulmonary hypertension (below). LV: left ventricle; LA: left atrium

TR JET – severe PAH

Tricuspid regurgitation (TR) jet documented by Doppler echo with peak gradient of 77.3 mm Hg, suggesting severe pulmonary arterial hypertension (PAH). Doppler line is seen across the right ventricle and atrium in the upper panel with sampling in the region of the tricuspid valve. The right ventricular pressure is estimated by adding the expected right atrial pressure from the observed jugular venous pressure to the peak TR gradient.

TR MILD PAH

TR jet in a case with mild PAH with gradient of only 21.7 mm Hg. The jet envelope is incomplete, indicating mild TR.

Parasternal long axis view in echocardiography

Johnson Francis — Sun, 24 Jul 2011 17:22:55 +0000

Parasternal long axis view in echocardiography

Parasternal long axis view is usually the first view which is obtained in echocardiography. The transducer is placed in the left parasternal region with the beam oriented to image the heart in the long axis view. RV: right ventricle; IVS: interventricular septum; AO: aorta; LV: left ventricle; LA: left atrium. The dense interface of the pericardium is seen posterior to left atrium and ventricle. But echocardiography is not that good for assessing the thickness of the pericardium, though it is excellent for assessment of pericardial effusion. This is because the interface is highly echogenic and the thickness can be over estimated as in this case.