A simple device to reproduce the spatial orientations of the thorax and transducer for serial M-mode and two-dimensional echocardiograms

The relationship of mitral annular shape to the diagnosis of mitral valve prolapse

The geometric or anatomic diagnosis of mitral valve prolapse, as opposed to the pathologic diagnosis of myxomatous valve disease, is based on the relationship of the mitral leaflets to the surrounding anulus. Current echocardiographic criteria for this diagnosis include leaflet displacement above the annular hinge points in any two-dimensional view; implicit in this equivalent use of intersecting views is the assumption that the mitral anulus is a euclidean plane. Prolapse by these criteria is found in a surprisingly large proportion of the general population. In most of these individuals, however, prolapse is present in the apical four-chamber view and absent in roughly orthogonal long-axis views of the left ventricle. This frequently observed discrepancy between leaflet-annular relationships in intersecting views suggests an underlying geometric property of the mitral apparatus that would produce the appearance of prolapse in one view without actual leaflet distortion. To address this possibility, a model of the mitral valve and anulus was constructed. When the model anulus was given a nonplanar, saddle-shaped configuration, the clinical observations were reproduced: the leaflets appeared to lie above the low points of the anulus in one plane, and below its high points in a perpendicular plane. Therefore, the appearance of mitral valve prolapse can occur without actual leaflet displacement above the most superior points of the mitral anulus if the anulus is nonplanar. To determine whether this pattern is reflected in the human mitral anulus, two-dimensional echocardiographic views of the mitral apparatus were obtained by rotation about the cardiac apex in 20 patients without evident annular or rheumatic valvular disease. In all cases the mitral anulus, as reconstructed from these views, had a nonplanar systolic configuration, with high points located anteriorly and posteriorly. This is consistent with the findings of other groups in animals, and would favor the appearance of prolapse in the four-chamber view and its absence in long-axis views that are oriented anteroposteriorly. This model can therefore explain the frequently observed discrepancy between leaflet-annular relationships in roughly orthogonal views. It challenges the assumption that the mitral anulus is planar as well as the diagnosis of prolapse in many otherwise normal individuals based on that assumption.

Simplified echocardiographic measurement of the mitral anulus

Postmortem, clinical, and experimental observations suggest an approximate elliptical shape for the mitral valve anulus, limiting the accuracy of single-diameter measurements in estimating annular area and circumference. A detailed method has been reported which uses six apical echocardiographic views at 30-degree rotational intervals to measure the mitral anulus, providing results comparable with pathologic and experimental reports. Annular data from nine normal subjects and 18 patients with dilated cardiomyopathy were analyzed to test a simplified measurement procedure. Assuming an elliptical shape, mitral annular area (MAA) and mitral annular circumference (MAC) were calculated by means of major (usually corresponding to the four-chamber view) and minor diameters from two orthogonal apical planes. Assuming a circular shape, MAA and MAC were also estimated by means of single annular diameters obtained from both an apical four-chamber and a parasternal long-axis view. Systolic and diastolic points were analyzed together, providing an n = 54 in the linear regressions. The two-plane results in MAA and MAC were nearly identical to those from the six-plane method, with very close correlation (r = 0.982 to 0.990). The single-plane results systematically overestimated MAA and MAC, with less correlation (apical, r = 0.943 to 0.963; parasternal, r = 0.852). Thus, while single-diameter measurements may correlate with global changes in annular size, the two-plane method represents a simplified but accurate method for estimating MAA and MAC in humans.

Paradoxical deterioration of left ventricular asynergy after administration of nitroglycerin

The effects of nitroglycerin on segmental asynergy were studied by 2-dimensional echocardiography. Forty-five patients with coronary artery disease and segmental wall motion abnormality at rest were examined, 31 with Q-wave and 14 with only ST-T abnormalities. Left ventricular (LV) echocardiograms were recorded from the LV apex in 4 planes, obtained by systematically rotating the transducer at 45 degrees intervals around the mitral office, using a mechanical device. Sixteen LV segments were analyzed in each patient on real-time display by 2 observers independently. The wall motion analysis was classified as normal, hypokinetic, akinetic or dyskinetic. Of 720 segments, 596 were agreed on by 2 observers in the assessment of wall motion before and after administration of nitroglycerin: 334 segments (56%) showed no change in wall motion, 206 (35%) showed improvement of wall motion and 56 (9%) showed worsening of myocardial asynergy after nitroglycerin. These data suggest that administration of nitroglycerin may result in unexpected worsening of segmental asynergy. This may be secondary to an adverse effect of a decrease in perfusion pressure in critically occluded arteries or may represent a coronary steal phenomenon.

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.

The tricuspid valve annulus: study of size and motion in normal subjects and in patients with tricuspid regurgitation

The tricuspid valve leaflets and their annular attachments were recorded by two-dimensional echocardiography from a view of the right ventricular inflow tract obtained by placing the transducer at an intermediate position between the left ventricular apex and the left lower sternal border. The transducer was rotated, and recordings were made at 30 degrees rotational intervals around the circumference of the tricuspid valve annulus. The cyclical pattern of variations in tricuspid annular size was studied with 12 measurements made during the cardiac cycle in five normal subjects. Annular areas and circumferences were measured. The overall motion pattern was similar to that reported in normal mitral valve annular study. Subsequently, in 16 normal subjects and 18 patients with tricuspid regurgitation, the maximum and minimum tricuspid annular sizes and their percent reduction were measured. The mean maximum annular circumference and area were 11.9 +/- 0.9 cm (mean +/- SD) and 11.3 +/- 1.8 cm2 in normal subjects. They were significantly greater in tricuspid regurgitation (14.0 +/- 0.7 cm and 15.8 +/- 1.8 cm2, respectively). The mean minimum annular sizes were much larger in tricuspid regurgitation (12.5 +/- 0.6 cm and 13.0 +/- 1.4 cm2) than in normal subjects (9.6 +/- 0.9 cm, 7.6 +/- 1.4 cm2). Thus, the percent reduction of annular circumference and area were significantly decreased in tricuspid regurgitation. For anatomic correlations, measurements of the tricuspid annular circumference were made at autopsy in 18 hearts without underlying valvular disease. The annular circumference was measured in the fresh and fixed states. The measurement in the fresh state was 13.5 +/- 0.8 cm and in the fixed state was 12.0 +/- 0.8 cm. The values measured in the fixed hearts were more similar to measurements obtained by echocardiography in a group of normal subjects. Thus, tricuspid annular reconstruction by the new two-dimensional echocardiographic method provides additional information about normal and abnormal size and function of the tricuspid valve annulus.

The correlates of an abnormal first heart sound in mitral-valve-prolapse syndromes

In 52 patients with mitral-valve prolapse we studied the intensity of the first heart sound (S1) in relation to the timing of the prolapse and to the presence of leaflet tip coaptation. Sixteen normal subjects served as controls. With two-dimensional echocardiography, three distinct groups were identified. Sixteen patients had early systolic mitral prolapse coincident with initial mitral-leaflet coaptation at the S wave on electrocardiography. Twenty-one had middle to late systolic mitral prolapse. Fifteen had flail mitral leaflet without normal leaflet coaptation at the free margins. The intensity of S1 was expressed as the ratio of the S1 amplitude to that of the aortic component of the second heart sound. This ratio was greater in the patients with early prolapse (6.2 +/- 3.1, mean +/- S.D.) than in the controls (1.4 +/- 0.7) (P less than 0.01). The ratio was reduced in patients with flail valves (0.3 +/- 0.5) (P less than 0.01) and did not differ between patients with middle to late prolapse (1.3 +/- 0.6) and controls. We conclude that the amplitude of S1 may provide a clue to the type and timing of mitral-valve prolapse.

Size and motion of the mitral valve annulus in man. I. A two-dimensional echocardiographic method and findings in normal subjects

Using wide-angle, phased-array, two-dimensional echocardiography, mitral leaflets and their annular attachments were recorded from a view close to the standard apical four-chamber view. The transducer was rotated and recordings were made at 30 degrees rotational intervals around the circumference of the mitral valve annulus. To reconstruct the annulus, the diameters (chords) from each rotational interval were arranged around a reference point. This was done for 12 times during the cardiac cycle. Annular areas were planimetered and circumferences measured. Correlation was good for areas reconstructed and measured by the same observer on separate occasions (r = 0.963) and by two different observers (r = 0.987). In 11 normal subjects the annular area index (area divided by body surface area) increased during diastole to a maximum of 3.8 +/- 0.7 cm2/m2 (mean +/- SD) in late diastole. There was presystolic followed by systolic narrowing to a minimum in midsystole. The mean reduction in area was 26 +/- 3%. The maximal annular circumference was 9.3 +/- 0.9 cm and the mean reduction in circumference was 13 +/- 3%. The overall motion pattern was similar to that reported in experimental studies in the dog. Mitral annular reconstruction may provide new information about normal and abnormal function of the mitral valve apparatus.

Reproducibility of left ventricular internal dimensions with M mode echocardiography: effects of heart size, body position and transducer angulation

Analysis was made of the variables of heart size, body position and transducer angle affecting the reproducibility of left ventricular internal dimensions as measured with M mode echocardiography. Echocardiograms were recorded in 24 subjects as the thorax was incrementally rotated and tilted. Transducer angle was noted from a three plane level attached to the probe. Constants were the technician, transducer placement and the interpreter. Heart rates varied insignificantly; respirations were held. Groups A and B were defined by their initial left ventricular internal dimensions at end-diastole (LVIDd): 49 +/- 5.9 and 73 +/- 8.6 mm (group mean +/- standard deviation). With body position constant the measurement error between duplicate recordings of LVIDd was +/- 1.2 mm (coefficient of variation = 1.8 percent) in Group A and +/- 4.5 mm (coefficient of variation = 4.6 percent) in Group B (p less than 0.001). Transducer angle varied 12 degrees between duplicate recordings in both groups. As the position of the thorax changed, the transducer followed, maintaining approximately the same incline with the chest wall. In both groups errors for combined LVIDd recorded with rotation and tilt, respectively, were unchanged from the duplication error. Thus, when the spatial orientation between the transducer and heart is held constant, it is the size of the heart that determines the reproducibility of the measurement of left ventricular internal dimensions.