Reevaluation of the role of atrial systole to cardiac hemodynamics: evidence for pulmonary venous regurgitation during abnormal atrioventricular sequencing.

Twenty open-chest dogs with experimental AV heart block were evaluated hemodynamically, angiographically, and by M-mode echocardiography to further elucidate mechanisms whereby abnormal AV sequencing results in decreased cardiac hemodynamics. During fixed-rate AV pacing, there was a consistent decrease in cardiac output, left ventricular and aortic pressures, and left ventricular dimensions with an increase in left atrial pressure as the AV interval was decreased from 100 to 0 msec, and there were further changes when the AV interval was set at -50 and -100 msec. The hemodynamic consequences of atrial fibrillation with regular ventricular rhythms were similar to the effects of an AV interval of 0 msec. It is important to note that retrograde blood flow into the pulmonary venous system (pulmonary venous regurgitation) was demonstrated by left atrial angiography at AV intervals of both -50 and -100 msec. However, left ventricular angiography failed to reveal mitral regurgitation during fixed-rate pacing at any AV interval or during atrial fibrillation with regular ventricular rates. Thus, during tachyarrhythmias characterized by abnormal AV sequencing, not only is there the loss of active atrial contribution to ventricular filling but there is also evidence for a retrograde or "negative atrial kick" further compromising cardiac hemodynamics.

Atrial alternans: experimental echocardiographic and hemodynamic demonstration during programmed pacing.

Simultaneous hemodynamic and echocardiographic recordings were used to demonstrate mechanical atrial alternans during programmed atrioventricular (A-V) pacing in five open chest dogs. Each animal was studied in two stages, first with the A-V conduction system intact (phase I) and later after the experimental induction of complete A-V block (phase II). Atrial alternans was demonstrated during rapid atrial stimulation at cycle lengths ranging from 250 to 120 ms. During phase I, rapid atrial pacing resulted in complex combinations of variable A-V conduction disturbances with superimposed atrial and ventricular alternans. During phase II, atrial alternans could be observed during a programmed prolonged pause in ventricular activity. It is anticipated that this method will facilitate recognition of atrial alternans in various clinical situations and shed further light on its possible hemodynamic significance.

Tricuspid valve prolapse diagnosed by cross-sectional echocardiography.

Cross-sectional echocardiography utilizing the apical and longitudinal right ventricular inflow tract views was used to investigate the tricuspid valve in 64 patients with mitral valve prolapse and 16 controls who had no angiographic or echocardiographic evidence of mitral valve prolapse. The tricuspid valve leaflets and their coaptation point in systole were found to be below (towards the right ventricular apex) the level of the tricuspid valve ring in systole in all controls. Tricuspid valve prolapse, defined as the leaflet(s) of the tricuspid valve lying above the tricuspid valve ring level within the right atrium, was seen in 31/64(48 percent) of patients with mitral valve prolapse. The right ventricular inflow tract view demonstrated tricuspid valve prolapse most readily compared to the apical view, and 29 of the 31 patients with tricuspid valve prolapse had prolapse of at least two leaflets of the tricuspid valve. The 31 patients with both mitral and tricuspid valve prolapse, when compared to the 33 patients with mitral valve prolapse alone, had more symptomatology and abnormal physical findings.

Apical cross-sectional echocardiography. Standard for the diagnosis of idiopathic mitral valve prolapse syndrome.

In light of the nonspecificity of left ventricular angiography and physical examination, and the limitations of M-mode echocardiography to define the presence of mitral valve prolapse syndrome, we evaluated left ventricular longitudinal and apical four-chamber tomographic views of cross sectional echocardiography in 19 subjects with normal left ventricular cineangiography and in 5 patients with congestive cardiomyopathy. None had auscultatory findings suggestive of mitral valve prolapse syndrome. In all 24 control subjects, the apical view demonstrated the coaptation point and the leaflets of the mitral valve to lie inside the left ventricular cavity. A retrospective analysis of 900 consecutive cross sectional echocardiographic studies revealed 105 subjects with no evidence of structural heart disease other than the presence of the mitral valve leaflets in the left atrium in systole defining the existence of idiopathic mitral valve prolapse syndrome. Both mitral leaflets were prolapsed in 90 percent of the involved populations, and the apical tomographic cross sectional echocardiographic view was superior to the left ventricular longitudinal view for the detection of anterior leaflet prolapse. These data suggest that the apical cross sectional view may be the single best technique to define the presence of idiopathic mitral valve prolapse syndrome.

Echocardiographic detection of coronary artery disease. Detection of effects of ischemia on regional myocardial wall motion and visualization of left main coronary artery disease.

M mode and cross-sectional echocardiographic studies at rest have been used to detect regional left ventricular wall motion abnormalities as a sign of hemodynamically significant coronary artery disease. These techniques have proved to be fairly specific but not highly sensitive. Detection of new regional wall motion abnormalities with cross-sectional echocardiography during exercise appeared practical in 80 percent of patients in preliminary studies; the finding of such abnormalities is highly specific for the presence of coronary artery disease and, with this approach, the sensitivity of echocardiography is improved. Thus, patients with anatomically severe coronary artery disease on angiography may not manifest an echocardiographic abnormality in regional wall motion even during exercise. The direct noninvasive detection of the left main coronary artery in up to 90 percent of patients studied with cross-sectional echocardiography using the short axis or apical approach, or both, has been well defined. A high sensitivity and specificity of detecting anatomically severe left main coronary artery disease using the criteria of both luminal impingement and the presence of high intensity echoes have been confirmed. Further advances in imaging techniques may allow for better definition of the coronary arterial tree.

Tricuspid regurgitation in tricuspid valve prolapse demonstrated with contrast cross-sectional echocardiography.

To determine the prevalence of tricuspid regurgitation in patients with tricuspid valve prolapse and to define further the criteria for the diagnosis of tricuspid regurgitation on contrast echocardiography, evaluation was made of 45 patients who had adequate contrast studies. There were four groups of patients: Group A, 10 healthy control subjects with no evidence of structural heart disease on cardiac catheterization; group B, 10 patients with classic clinical evidence of tricuspid regurgitation; group C, 10 patients with cross-sectional echocardiographic evidence of mitral valve prolapse without tricuspid valve prolapse; and group D, 15 patients with both mitral and tricuspid valve prolapse on cross-sectional echocardiography. Tricuspid regurgitation was sought in each group by using the subxiphoid echocardiographic approach with peripheral venous injection of saline solution. The diagnosis required the presence of microcavitations in both the inferior vena cava and hepatic veins for at least three consecutive cardiac cycles. Tricuspid regurgitation was observed in no patients in group A, 10 of 10 patients in group B, 0 of 10 in groups C and 6 of 15 (40 percent) in group D. Contrast cross-sectional echocardiography proved to be a reliable technique for identifying tricuspid regurgitation with a high degree of specificity and sensitivity. Patients with tricuspid valve prolapse had a 40 percent prevalence rate of tricuspid regurgitation. This finding may identify a subgroup that requires particularly careful clinical follow-up care.

Echocardiographic features of atrioventricular and ventriculoatrial conduction.

The potential application of diagnostic ultrasound to understanding of the hemodynamic effects of various rhythm and conduction disturbances has not been fully explored. To investigate the change in cardiac function associated with various atrioventricular (A-V) sequencing intervals during cardiac pacing, simultaneous M mode and two dimensional echocardigraphic and hemodynamic studies were performed in 23 dogs. One to one A-V and ventriculoatrial (V-A) sequential pacing at cycle lengths of 400 and 300 ms revealed a stepwise reduction in left ventricular pressure and cardiac output as the A-V interval was changed from +100 to -100 ms. These reductions in cardiac hemodynamics were associated with decreases in left ventricular and increases in left atrial dimensions determined with echocardiography. Mitral valve excursion and the duration of valve opening remained constant over the entire range of A-V intervals. There was angiographic evidence of retrograde blood flow from the left atrium into the pulmonary venous system at an A-V interval of -50 and -100 ms, but no evidence of mitral regurgitation. Thus, correlative echocardiographic and hemodynamic studies can suggest multiple pathophysiologic mechanisms contributing to the decrements in cardiac function observed during tachyarrhythmias with intact A-V conduction as well as those occurring consequent to A-V nodal Wenckebach cycles.

Detecting left main coronary artery disease by apical, cross-sectional echocardiography.

To test the feasibility of imaging the left main coronary artery (LMCA) noninvasively as a means of detecting left main coronary artery disease, we studied 73 patients who underwent cardiac catheterization and cross-sectional echocardiography. Fifty-two had a normal LMCA (controls) and 21 had significant obstruction (greater than or equal to 50% luminal reduction). The apical, tomographic, cross-sectional, phased-array, echocardiographic approach was used, and the LMCA was imaged in 52 of 73 patients (71%). In 34 of 36 controls (94%) the LMCA was correctly judged as having no luminal obstruction. In the other two, and asymmetric, high-intensity echo in one wall of the artery suggested atherosclerotic disease, but coronary angiography revealed no obstruction. In 12 of 16 patients (75%) in whom significant LMCA disease was imaged, obstruction was predicted by echocardiographic criteria of either luminal irregularity or an asymmetric, high-intensity echo in the arterial wall. This preliminary study suggests that cross-sectional echocardiography appears to be a feasible, noninvasive technique to image the LMCA and to detect hemodynamically significant luminal obstruction.

Rheumatic mitral stenosis:cross-sectional echocardiographic analysis.

Twenty-one patients with rheumatic mitral stenosis diagnosed by both M-mode echocardiography and hemodynamic findings were subjected to detailed cross-sectional echocardiographic studies. The age of the patients ranged from 27 to 79 years with 76% females. Left ventricular longitudinal, short axis, and apical four-chamber cross-sectional echocardiographic views were obtained in each patient. Three predominant patterns of anterior mitral leaflet motion on left ventricular longitudinal view were observed and correlated with the severity of mitral stenosis: Pattern A (eight patients) with diastolic leaflet doming and restricted leaflet tip motion. Pattern B (eight patients) tip and body leaflet motion, and Pattern C (five patients) with the entire leaflet motion restricted. Mitral valve prolapse as a rebound phenomenon was observed in three patients who had marked leaflet doming in Pattern A and two had severe obstruction. The longitudinal cross-sectional echocardiography was superior to the apical view in assessing the diastolic doming motion of the anterior mitral leaflet. Thus, longitudinal cross-sectional echocardiographic analysis of the pliability and degree of doming of the anterior of the pliability and degree of doming of the anterior mitral leaflet is valuable in estimating the severity of mitral stenosis.

A new approach to visualize the left main coronary artery using apical cross-sectional echocardiography.

Patients undergoing coronary arteriography were studied to evaluate the feasibility of use of cross-sectional echocardiography to detect the left main coronary artery. Visualization of the left main coronary artery from the cardiac apex was attempted using a cranial transducer angulation. With this approach, the left main coronary artery was adequately visualized in 27 of 35 consecutive patients (77 percent) who were prospectively evaluated; in 12 of the 27 the bifurcation was clearly seen. In 26 of the 27 patients cross-sectional echocardiography correctly assessed the patency of the left main coronary artery as judged with coronary angiography. One patient had a false positive echocardiographic study; there were no false negative studies. A comparison of the short axis versus apical cross-sectional techniques in another group of 30 patients revealed the superiority of the apical approach in visualization of the left main coronary artery and its bifurcation; combined use of both techniques allowed for a 93 percent (rate of) success. Thus, apical cross-sectional echocardiography permits visualization of the left main coronary artery and its bifurcation and, therefore, has the potential for detecting left main coronary obstructive lesions.

Cross-sectional echocardiographic spectrum of papillary muscle dysfunction.

Cross-sectional echocardiography identified two abnormal patterns of mitral valve closure in 14 patients with mitral regurgitation due to papillary muscle dysfunction: (1) in three patients with an akinetic inferior-posterior wall but normal cavity size, papillary muscle fibrosis was associated with late systolic mitral valve prolapse, and (2) in nine patients with ventricular dilatation or ventricular aneurysm, the point of mitral valve coaptation was displaced towards the apex of the left ventricle. In two of these patients both abnormalities were observed. In contrast, abnormal patterns were identified in only four of a group of 40 patients without angiographic evidence of mitral regurgitation (10, normal; 27, coronary artery disease; three, congestive cardiomyopathy). Thus, cross-sectional echocardiography can be useful to identify mitral regurgitation secondary to papillary muscle dysfunction.

Cross-sectional echocardiographic detection of aortic ring abscess in bacterial endocarditis.

The diagnosis of aortic ring abscess by cross-sectional echocardiography has not been reported. In this paper, a case of bacterial endocarditis of the aortic valve extending to the aortic ring and the mitral valve is reported. The role of cross-sectional echocardiography in defining the anatomic distortion of the aortic valve in bacterial endocarditis and its complications is emphasized. This study would indicate that early diagnosis of aortic ring abscess is feasible by cross-sectional echocardiography.

The role of cross-sectional echocardiography in the diagnosis of flail mitral leaflet.

Cross-sectional echocardiography was performed on two patients with mitral regurgitation in whom M-mode echocardiographic findings were not specific for the etiology of mitral regurgitation. In one patient, flail motion of the free edge of the anterior mitral leaflet into the left atrium was demonstrated only by cross-sectional echocardiograms. In the second patient, the flail posterior mitral leaflet was suggested to be a result of bacterial endocarditis. Cross-sectional echocardiograms clearly identified a flail motion of a mass of vegetation attached to the posterior mitral leaflet. Thus, cross-sectional echocardiography can provide critical information in recognizing patients with a flail mitral leaflet.