Pravin M. Shah

Assessment of right ventricular function using two-dimensional echocardiography☆

With the use of two-dimensional echocardiography (2DE), we analyzed apical and subcostal four-chamber views for evaluation of right ventricular (RV) function in 30 individuals as compared to RV ejection fraction (RVEF) obtained by radionuclide angiography. In addition to previously reported parameters of changes in areas and chords, a new simple measurement of tricuspid annular excursion was correlated with RVEF. A close correlation was noted between tricuspid annular plane systolic excursion (TAPSE) and RVEF (r = 0.92). The RV end-diastolic area (RVEDA) and percentage of systolic change in area in the apical four-chamber view also showed close correlation with RVEF (r = -0.76 and 0.81); however, the entire RV endocardium could only be traced in about half of our patients. The end-diastolic transverse chord length and the percentage of systolic change in chord length in the apical view showed a poor correlation with RVEF. The correlation between RVEF and both areas and chords measured in the subcostal view was poor. It is concluded that the measurement of TAPSE offers a simple echocardiographic parameter which reflects RVEF. This measurement is not dependent on either geometric assumptions or traceable endocardial edges. When the endocardial outlines could be traced, the apical four-chamber view was superior to the subcostal view in assessment of RV function.

Abnormal mitral valve coaptation in hypertrophic obstructive cardiomyopathy: proposed role in systolic anterior motion of mitral valve.

Two dimensional echocardiographic evaluation utilizing the apical four chamber and apical long axis views was made in 10 normal subjects and 35 patients with hypertrophic cardiomyopathy, including 16 without and 19 with systolic anterior motion of the mitral valve. Mitral valve leaflets were imaged throughout the cardiac cycle. The normal subjects and the patients with hypertrophic cardiomyopathy without systolic anterior motion demonstrated mitral valve coaptation that seemed to involve the distal tip of the anterior leaflet. In contrast, patients with hypertrophic cardiomyopathy with systolic anterior motion demonstrated abnormal coaptation, so that the posterior leaflet coapted with a mid portion of the anterior leaflet, leaving a distal residual anterior leaflet in the left ventricle during systole. A sharp angulation of this distal leaflet in mid systole toward the interventricular septum is thought to represent systolic anterior motion. It is speculated that abnormal mitral leaflet coaptation in necessary for development of leaflet systolic anterior motion, which is correlated with dynamic left ventricular outflow gradients in hypertrophic obstructive cardiomyopathy.

Digital image processing of two dimensional echocardiograms: Identification of the endocardium

Digital computer image-processing techniques were applied to two dimensional echocardiograms to improve the accuracy of cardiac spatial measurements by enhancing endocardial recognition. Images were photographed from the two dimensional echocardiographic monitor and digitized using an optical densitometer. Image-processing algorithms were applied to the digitized images as follows: (1) Multiple images were averaged; (2) a gray level threshold was chosen to separate the image into tissue and cavity regions on the basis of amplitude (brightness) of the returning echoes; (3) endocardium was traced between the regions; (4) endocardial position was confirmed by matching this boundary with a contrast edge map of the original images; and (5) the endocardial boundaries were tested by comparison with simultaneous M mode echocardiograms. A linear correlation was found between M mode and computer-processed two dimensional echocardiographic measurements of ventricular septal thickness (r = 0.88); this was superior to the correlation between M mode and unprocessed two dimensional echocardiographic septal measurements (r = 0.55). The correlations between M mode and processed or unprocessed two dimensional echocardiographic measurements of left ventricular internal dimension were similar (r = 0.89 and 0.85, respectively), but the slope of the regression line for the processed data more closely approximated the line of identity (p less than 0.05). It is concluded that endocardial outlines derived with use of digital image-processing techniques lead to left ventricular measurements that correlate more closely with M mode measurements than do dimensions derived from unprocessed two dimensional echocardiography.

M-mode echocardiography in constrictive pericarditis

M-mode echocardiograms from 40 patients with proven constrictive pericarditis and 40 subjects without evidence of cardiac disease were reviewed for features previously described in constrictive pericarditis. In this large series, no single feature of the M-mode echocardiogram could be considered diagnostic, although a pattern of normal left ventricular size and systolic function, mild left atrial dilation, flattened diastolic left ventricular posterior wall motion and abnormal septal motion was found in most patients. It is concluded that the M-mode echocardiogram can provide findings suggestive of constrictive pericarditis but must be used in conjunction with hemodynamic and other studies to establish the diagnosis.

Doppler evaluation of bioprosthetic and mechanical aortic valves: Data from four models in 107 stable, ambulatory patients

To test the applicability of Doppler ultrasound in the evaluation of prosthetic valve function, 107 patients with normal ejection fractions in whom Starr-Edwards, Björk-Shiley, Carpentier-Edwards, and Hancock models had been implanted in the aortic position were examined. Maximal transvalvular velocity was recorded by non-imaging continuous wave Doppler ultrasound. Means of maximal velocities by model and size ranged from less than 2 to 4 m/sec. The Starr-Edwards valve showed the highest velocities, the Björk-Shiley the lowest, and the bioprosthetic models showed velocities in between. A significant inverse relation between velocity and size, and standard deviations averaging +/- 14% enabled the technique to measure differences between sizes of the same model. Aortic regurgitation was detected in 24% of the patients. This study, conducted in well and stable patients, established values for maximal velocity across normally functioning aortic mechanical and tissue prostheses of different models and sizes. The intersubject variability was relatively small which, together with a previously shown minimal intrasubject variability, was testimony to a methodology that should prove useful in longitudinal postoperative evaluations.

Atrial systolic notch on the interventricular septal echogram: An echocardiographic sign of constrictive pericarditis

Interventricular septal motion during ventricular diastole was analyzed using M-mode echocardiography in 13 patients with constrictive pericarditis and 12 patients with restrictive cardiomyopathy. In seven of eight patients with constrictive pericarditis in sinus rhythm, an abnormal atrial systolic notch was observed consisting of abrupt initial posterior motion toward the left ventricle approximately at the middle of the P wave and subsequent anterior motion at the end of the P wave and termination before the R wave. This notch was absent during atrial premature beats that were recorded in two patients. The atrial systolic notch was not observed in any patient with restrictive cardiomyopathy. The septal notch in early ventricular diastole previously described in constrictive pericarditis was seen in 62% of patients with constrictive pericarditis and 25% of patients with restrictive cardiomyopathy. Thus, an abnormal atrial systolic notch may be an additional useful sign to differentiate constrictive pericarditis from restrictive cardiomyopathy. The mechanism may be related to transient late diastolic pressure gradients between both ventricles resulting from asynchrony of left and right atrial contractions.

Chronic effects of myocardial infarction on right ventricular function: A noninvasive assessment

To assess the chronic effects of myocardial infarction on right ventricular function, 48 subjects were studied utilizing radionuclide angiography and two-dimensional echocardiography. Ten were normal subjects (group I), 11 had previous inferior wall myocardial infarction (group II), 10 had previous anteroseptal infarction (group III), 11 had combined anteroseptal and inferior infarction (group IV) and 6 had extensive anterolateral infarction (group V). The mean (+/- standard deviation) left ventricular ejection fraction was 0.66 +/- 0.03 in group I, 0.58 +/- 0.02 in group II, 0.52 +/- 0.02 in group III, 0.33 +/- 0.03 in group IV and 0.33 +/- 0.01 in group V. No systematic correlation between left and right ventricular ejection fraction was observed among the groups. The mean right ventricular ejection fraction was significantly reduced in the presence of inferior myocardial infarction (0.30 +/- 0.03 in group II and 0.29 +/- 0.03 in group IV compared with 0.43 +/- 0.02 in group I [p less than 0.001]). The group II and IV patients also had increased (p less than 0.001) right ventricular end-diastolic area and decreased (p less than 0.001) right ventricular free wall motion by two-dimensional echocardiography. In the presence of anteroseptal infarction (group III), right ventricular free wall motion was increased (p less than 0.05) compared with normal subjects (group I). Thus, the effects of prior myocardial infarction on right ventricular function depend more on the location of infarction than on the extent of left ventricular dysfunction. Inferior infarction was commonly associated with reduced right ventricular ejection fraction and increased right ventricular end-diastolic area. The right ventricular free wall excursion was increased in the presence of anteroseptal infarction, suggested loss of contribution of interventricular septal contraction to right ventricular ejection.

Echocardiographic Evaluation of Normal and Prolapsed Tricuspid Valve Leaflets

The tricuspid valve was examined by 2-dimensional (2-D) echocardiography in 14 patients with tricuspid valve prolapse (TVP) and in 16 normal subjects. Individual leaflets were identified anatomically and for frequency of prolapse. Maximal and minimal anular sizes were measured. Multiple tomograms of the tricuspid anulus were recorded at 30 degrees intervals around the tricuspid anulus with the transducer placed at the right ventricular apex. Anuli were reconstructed from the 6 planes and corrected for body surface area. Three leaflets of the tricuspid valve could be anatomically identified in all patients. Prolapse of all 3 leaflets was observed in 6 patients, 2 leaflets in 5 and 1 in 3. Frequency of individual leaflet prolapse was 93% for the septal cusp, 86% for the anterior and 43% for the posterior. Maximal anular circumference and area in TVP were 7.9 +/- 0.6 and 8.9 +/- 1.3 cm2/m2, respectively--significantly larger than values in normal subjects (6.4 +/- 0.5 cm/m2 and 6.1 +/- 0.9 cm2/m2, respectively) (p less than 0.001). Percent reductions in circumference and area in TVP were 14 +/- 3 and 25 +/- 5%, respectively--significantly smaller values than in normal subjects (19 +/- 4 and 33 +/- 4%, respectively). Tricuspid regurgitation (TR) was detected by contrast echocardiography in 7 of 14 patients with TVP. The severity of TR appeared to be minimal in 6 of the 7 patients, and was not associated with an increase in anular size. Thus, TVP is associated with anular dilatation irrespective of associated TR, probably as a primary pathologic characteristic.

Echocardiography in Congestive or Dilated Cardiomyopathy

Echocardiography plays an important role in the evaluation of patients with congestive or dilated cardiomyopathy. Its role in diagnosis consists of demonstration of ventricular and atrial chamber dilation and assessment of left ventricular systolic function. A subgroup of patients with depressed function but with no significant left ventricular dilation are described. Echocardiographic detection of intracavitary thrombi in the left ventricular cavity has a high predictive accuracy in excess of 90%. The pathophysiology of mitral and tricuspid regurgitation in relation to annular size, valve dysfunction, and chamber dilation is readily assessed by two-dimensional echocardiography. The Doppler methods are useful to measure cardiac output, to quantify pulmonary hypertension, and to assess left ventricular systolic and diastolic functional abnormalities. An important role of echocardiography in prognosis relates to predictive value of M-mode parameters of left ventricular size, wall thickness, and function in long-term survival, as observed in a prospective multicenter study.

Angled interventricular septum on echocardiography: Anatomic anomaly or technical artifact?

An acutely angled interventricular septum has been reported to constitute a distinct two-dimensional echocardiographic geometric pattern that may permit a false M-mode echocardiographic recording of asymmetric septal hypertrophy. In light of experience suggesting that the angle between the aortic root and interventricular septum varied with the intercostal space of the transducer, 45 subjects were prospectively studied by two-dimensional and M-mode echocardiography. Parasternal long- and short-axis views were obtained from two to four intercostal spaces in each subject. Two-dimensional echographic cursor-generated M-mode echocardiograms were obtained from the long-axis views; interventricular septal and left ventricular posterior wall thickness was measured from both the two-dimensional and M-mode echocardiograms. On two-dimensional echocardiography, the angle between the aortic root and septum became more acute as a progressively lower intercostal space was used (p less than 0.001). Although no change in septal thickness was apparent, the septal thickness significantly increased as a progressively lower intercostal space was used. On M-mode echocardiography, 21 subjects (47%) demonstrated asymmetric septal hypertrophy (septal/posterior wall thickness ratio greater than 1.3) from at least one intercostal space, but this was confirmed by the two-dimensional technique in only 4 subjects (9%). Thus, a two-dimensional echocardiographic recording of an angled interventricular septum can be produced by positioning the transducer in a low intercostal space, and caution must be used in the interpretation of asymmetric septal hypertrophy on M-mode echocardiograms. Two-dimensional echocardiography is a useful means of identifying subjects with apparent asymmetric septal hypertrophy that often may be the result of a technical artifact.