Charles R. Prince

Left atrial appendage thrombus is not uncommon in patients with acute atrial fibrillation and a recent embolic event: A transesophageal echocardiographics tudy

Objectives. The objective of this study was to determine the frequency of left atrial thrombus in patients with acute atrial fibrillation. Background. It is commonly assumed but unproved that left atrial thrombus in patients with atrial fibrillation begins to form after the onset of atrial fibrillation and that it requires ≥3 days to form. Thus, patients with acute atrial fibrillation (i.e., <3 days) frequently undergo cardioversion without anticoagulation prophylaxis. Methods. Three hundred seventeen patients (250 men, 67 women; mean [±SD] age 64 ± 12 years) with acute (n = 143) or chronic (n = 174) atrial fibrillation were studied by two-dimensional transesophageal echocardiography. Results. Left atrial appendage thrombus was present in 20 patients (14%) with acute and 47 patients (27%, p < 0.01) with chronic atrial fibrillation. In patients with a recent embolic event, the frequency of left atrial appendage thrombus did not differ between those with acute (5 [21%] of 24) and those with chronic (12 [23%] of 52, p = NS) atrial fibrillation. Patients with acute versus chronic atrial fibrillation, respectively, did not differ (p = NS) in mean age (64 ± 13 vs. 65 ± 11 years), frequency of concentric left ventricular hypertrophy (32% vs. 26%), hypertension (32% vs. 41%), coronary artery disease (35% vs. 39%), congestive heart failure (43% vs. 48%), mitral stenosis (4% vs. 7%) or mitral valve replacement (1.4% vs. 6%). The minimally detectable difference in proportions between patients with acute and chronic atrial fibrillation based on a power of 0.80 and base proportion of 0.20 was 14%. Conclusions. Left atrial thrombus does occur in patients with acute atrial fibrillation <3 days in duration. The frequency of left atrial thrombus in patients with recent emboli is comparable between those with acute and chronic atrial fibrillation. These data suggest that patients with acute atrial fibrillation for <3 days require anticoagulation prophylaxis or evaluation by transesophageal echocardiography before cardioversion and should not be assumed to be free of left atrial thrombus.

Transesophageal echocardiographic guidance of cardioversion in patients with atrial fibrillation

The role of TEE in the guidance of cardioversion of atrial fibrillation was studied. Thirty-seven (18%) of 206 patients had left atrial thrombus. Cardioversion was attempted in 153 patients receiving no (n = 107) or < 7 days (n = 46) of anticoagulation prophylaxis, in 27 patients after > or = 3 weeks of anticoagulation, and was cancelled in 26 patients, primarily on the basis of TEE findings. Left atrial thrombus was observed in 37 (18%) of 206 patients. No embolic complications occurred over a 4-week follow-up period. In 7 (41%) of 17 patients new left atrial appendage spontaneous echocardiographic contrast developed immediately after electric cardioversion. In this group, significant decreases occurred in the left atrial appendage maximal emptying shear rate (11.1 +/- 11.1 sec-1 vs 5.0 +/- 5.1 sec-1; p < 0.05), maximal filling shear rate (6.7 +/- 5.9 sec-1 vs 3.7 +/- 3.5 sec-1; p < 0.05), and peak emptying velocity (0.38 +/- 0.29 cm/sec vs 0.19 +/- 0.14 cm/sec; p < 0.05). In one patient a left atrial appendage thrombus formed after electric cardioversion. Left atrial thrombus resolved in 1 (5%) of 21 patients and became immobile in 0 (0%) of 16 patients after 3 to 5 weeks of anticoagulation but resolved (n = 9) or became immobile (n = 6) in 15 (71%) of 21 patients after > 5 weeks of anticoagulation. TEE-guided cardioversion was safely done without or with < 7 days of anticoagulation prophylaxis in selected patients, but the potential for left atrial thrombus to form after electric cardioversion makes anticoagulation advisable in all patients. The conventional recommendation of 3 to 4 weeks of anticoagulation prophylaxis before cardioversion is usually inadequate for left atrial thrombus to resolve or to become immobile.

Exercise-induced mitral regurgitation is a predictor of morbid events in subjects with mitral valve prolapse.

OBJECTIVES This study attempted to determine whether a subset of patients with mitral valve prolapse and no mitral regurgitation at rest will develop mitral regurgitation during exercise and have a higher than anticipated risk of morbid cardiovascular events. BACKGROUND Mitral regurgitation in patients with mitral valve prolapse identifies a subset of patients at higher risk for morbid events. However, mitral regurgitation in patients with mitral valve prolapse may be intermittent and could go unrecognized. A provocative test to unmask mitral regurgitation in these patients would be useful. METHODS Ninety-four adult patients with mitral valve prolapse and no mitral regurgitation at rest were studied during supine bicycle ergometry using color flow Doppler echocardiography in the apical four-chamber and long-axis views. Patients were prospectively followed up for morbid events. RESULTS Thirty (32%) of 94 patients had exercise-induced mitral regurgitation. Prospective follow-up (mean 38 months) showed more morbid events in the group with than without mitral regurgitation and included, respectively, syncope (43% vs. 5%, p < 0.0001), congestive heart failure (17% vs. 0%, p < 0.005) and progressive mitral regurgitation requiring mitral valve replacement surgery (10% vs. 0%, p < 0.05). Cerebral embolic events, endocarditis or sudden death were rare and not different between groups. CONCLUSIONS In patients with mitral valve prolapse without mitral regurgitation at rest, exercise provokes mitral regurgitation in 32% of patients and predicts a higher risk for morbid events.

Pulsed Doppler transesophageal echocardiographic determination of cardiac output in human beings: Comparison with thermodilution technique

Measurement of cardiac output is a clinically valuable and widely used index of cardiac function. Although transesophageal echocardiography has been used to assess left ventricular function, little data exist on the accuracy of this technique in the measurement of cardiac output. Therefore cardiac output derived by pulsed Doppler transesophageal echocardiography and thermodilution methods were compared in adult patients being mechanically ventilated. The left ventricular outflow tract diameter was determined from a transgastric long-axis view of the left ventricle by using the transverse plane and longitudinal plane of the transesophageal scope. The cross-sectional area of the left ventricular outflow tract was calculated from the diameter assuming a circular shape. Pulsed Doppler recordings were obtained at the left ventricular outflow tract. Doppler time-velocity integrals were measured from the leading edge of the velocity curve. Cardiac output derived by transesophageal echocardiography was calculated as time-velocity integral multiplied by left ventricular outflow tract area and heart rate. Cardiac output derived by transesophageal echocardiography from the transverse plane (n = 26) and longitudinal plane (n = 22) were correlated with simultaneous thermodilution measurements. Thermodilution-derived cardiac output demonstrated excellent correlation with cardiac output measured by using transesophageal echocardiography from the transverse plane (r = 0.97, SEE = 0.84 L/min; p < 0.0001) and longitudinal plane (r = 0.95, SEE = 0.97 L/min; p < 0.0001). Transesophageal echocardiography is a promising technique in the measurement of cardiac output and expands the clinical use of this modality in the assessment of cardiac function.

Coronary flow reserve assessment by dobutamine transesophageal doppler echocardiography

OBJECTIVES This study attempted to determine the sensitivity and specificity of coronary flow reserve derived using transesophageal echocardiography for left anterior descending coronary artery stenosis. BACKGROUND Transesophageal echocardiography can be used to measure coronary flow velocity and may provide a less invasive means of assessing coronary flow reserve. METHODS Seventy-eight adult patients were studied by pulsed Doppler transesophageal echocardiography of the proximal left anterior descending coronary artery during a control period and peak (i.e., 40 micrograms/kg body weight per min) dobutamine infusion. Coronary flow reserve index was calculated as the ratio of maximal diastolic coronary velocity at peak dobutamine infusion to the control level and was considered abnormal if < 1.81. Two-dimensional transesophageal left ventricular views were obtained for analysis of wall motion. RESULTS Coronary angiography showed > or = 70% (group A, n = 18), 0% to < 70% (group B, n = 21) and no (group C, n = 39) left anterior descending coronary artery diameter stenosis. An abnormal coronary flow reserve index did not differ from a new regional wall motion abnormality in sensitivity for left anterior descending coronary stenosis in group A (15 [83%] of 18 vs. 15 [83%] of 18, p = NS) but was significantly more sensitive in group B (12 [57%] of 21 vs. 2 [10%] of 21, p < 0.025). The specificity for no left anterior descending coronary stenosis in group C between a normal coronary flow reserve index and no new regional wall motion abnormality did not differ (87% vs. 97%, p = NS). CONCLUSION Doppler coronary flow reserve and two-dimensional dobutamine transesophageal echocardiography are equally sensitive for the detection of left anterior descending coronary stenosis > or = 70% and equally specific. However, Doppler coronary flow reserve, compared with two-dimensional dobutamine transesophageal echocardiography, is more sensitive for intermediate left anterior descending coronary stenosis and may play a significant adjunctive role to cardiac catheterization and other noninvasive techniques for assessing coronary artery disease.

Two-dimensional and Doppler transesophageal echocardiographic delineation and flow characterization of anomalous coronary arteries in adults

OBJECTIVES The purpose of this study was to examine the use of transesophageal echocardiography (TEE) in the identification and flow characterization of congenital coronary anomalies. BACKGROUND Congenital coronary anomalies in adults are rare but may cause serious cardiac complications. The use of TEE in evaluation of this entity has not been well defined. Very little is known regarding flow patterns in anomalous coronaries assessed by Doppler TEE. METHODS A total of 32 consecutive adult patients were studied using TEE to define the origin, course, and proximal flow pattern of suspected coronary anomalies. RESULTS Coronary anomalies identified using TEE included anomalous origin from the pulmonary trunk (n = 2), right sinus (n = 18), left sinus (n = 9), single coronary (n = 2), and left main coronary fistula (n = 1). Multiplane TEE performed in 20 cases simplified the delineation of more complex coronary anomalies. The origin was identified in all patients, proximal course delineated in 31, and proximal flow pattern characterized by pulsed Doppler in 23 of 32 patients. In 16 anomalous left main, left anterior descending, or left circumflex coronary arteries, an abnormal systolic flow pattern (ie, systolic/diastolic time-velocity integral ratio >1) occurred exclusively (P <.001) when the anomalous artery had an intermediate (100%; 5/5) versus anterior or posterior course (0%; 0/11) relative to the aortic and pulmonary artery trunks. A systolic flow pattern was also evident in 4 (80%) of 5 patients with an anomalous right coronary artery with an intermediate course. CONCLUSIONS TEE, particularly with a multiplane probe, has an important complementary role to coronary angiography in delineating the proximal course and pattern of flow in anomalous coronaries. Predominant systolic flow pattern in anatomically left proximal anomalous coronaries signifies an intermediate course between the aorta and the pulmonary trunk and may be clinically useful for risk stratification.

Dobutamine two-dimensional transesophageal echocardiographic stress testing for detection of coronary artery disease

Atrial pacing and dipyridamole transesophageal echocardiography have been shown to be sensitive and specific tests for the detection of coronary artery disease. However, the sensitivity and specificity of dobutamine transesophageal echocardiography have not been reported. The purpose of this study was to determine the feasibility, sensitivity, and specificity of dobutamine transesophageal echocardiography for the detection of coronary artery disease. Transesophageal echocardiographic assessment of left ventricular function was performed in 81 adult patients aged 62 +/- 12 years during stepwise infusion of dobutamine from 5.0 to 40 micrograms/kg/min. Ischemia was diagnosed by the development of severe hypokinesis, akinesis, or dyskinesis of a previously contractile left ventricular segment. Coronary artery disease was defined by angiography as a reduction in luminal diameter of > or = 70% of an epicardial or > or = 50% of the left main coronary artery. In patients who had undergone coronary artery bypass graft surgery, a stenotic bypass graft was defined as a reduction in luminal diameter of > or = 70%. In patients without previous CABG, significant coronary artery disease was present in 21 patients: 5 with single-vessel disease, 7 double-vessel disease, 8 triple-vessel disease, and 1 left main coronary disease. Dobutamine transesophageal echocardiography had a sensitivity of 90% (19 of 21) and specificity of 94% (49 of 52) for the detection of coronary artery disease. In patients with previous CABG (n = 8), the sensitivity and specificity for the detection of bypass graft stenosis were 100% (4 of 4) and 75% (3 of 4), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Two-dimensional transesophageal echocardiographic determination of mitral valve area in adults with mitral stenosis

Two-dimensional transthoracic echocardiography has been shown to be a reliable and accurate method of measuring stenotic mitral valve orifice area. Little data exist on the role of two-dimensional transesophageal echocardiography for this purpose. Thus in 45 adult patients with mitral stenosis mitral valve area was determined by direct planimetry with the use of two-dimensional transesophageal and transthoracic echocardiography. Transesophageal was less feasible than transthoracic echocardiography in the 45 patients (69% vs. 89%, p < 0.025). In 14 patients, two-dimensional transesophageal echocardiography was not feasible, primarily because of leaflet dropout. In 30 patients, transesophageal and transthoracic echocardiography were feasible, and measurements of mitral valve area by the two techniques correlated well (r = 0.91, SEE = 0.33 cm2, p < 0.0001). Mean mitral valve orifice area determined by transesophageal echocardiography (1.54 +/- 0.75 cm2; range 0.56 to 3.49 cm2) and by transthoracic echocardiography (1.55 +/- 0.78 cm2; range 0.62 to 3.68 cm2) did not differ (p = NS). The absolute (0.24 +/- 0.22 cm2) and percent (19% +/- 21%) differences between mitral valve area determined by transesophageal versus transthoracic echocardiography were small. These data show that mitral valve area in patients with mitral stenosis can be accurately measured by direct planimetry with two-dimensional transesophageal echocardiography. Technical refinements such as lateral-gain-compensation features may improve the feasibility of two-dimensional transesophageal echocardiography for measurements of mitral stenosis area, and this technique may become an adjunct to transthoracic echocardiography in the assessment of severity of mitral stenosis.

Angle of incidence does not affect accuracy of mitral stenosis area calculation by pressure half-time: Application to Doppler transesophageal echocardiography

Continuous wave Doppler transesophageal echocardiography (TEE) may allow the estimation of stenotic mitral valve area. Intuitively the posterolateral position of the transducer appears to limit the application of TEE for this purpose because of the excessive angle of incidence to mitral valve inflow. However, algebraic equations can be used to predict that the angle of incidence should not affect mitral valve area derived by using pressure half-time. To test the validity of this prediction and the potential application of Doppler TEE to estimate mitral valve area, 28 patients (21 women, 7 men) with a mean age of 59 +/- 14 years with mitral stenosis were studied by continuous wave transthoracic echocardiography (TTE) and TEE guided color flow Doppler. TTE was performed from the apical four-chamber (TEE-0) and a modified parasternal four-chamber (TTE-MAL) plane as a means of intentionally increasing the angle of incidence. TEE was done by using the horizontal (TEE-HAX) and vertical (TEE-VAX) planes. Mitral valve area was calculated by pressure half-time method. Mean mitral valve area did not differ (p = not significant [NS]) between TTE-0 (1.26 +/- 0.84 cm2), TTE-MAL (1.37 +/- 0.94 cm2), TEE-HAX (1.39 +/- 0.92 cm2), and TEE-VAX (1.35 +/- 0.89 cm2). The estimated mean angle of incidence during TTE-MAL was 45 +/- 12 degrees (range 21 to 68 degrees). Six (21%) of 28 and 9 (32%) of 28 patients had an underestimation of transmitral peak velocities with TEE from the horizontal or vertical planes, respectively. However, excellent correlations were found between mitral valve area derived by using TEE-0 versus TTE-MAL (r = 0.97; SEE = 0.25 cm2; intercept = 0.02 cm2; slope = 1.08; and p = 0.0001), TEE-HAX (r = 0.91; SEE = 0.39 cm2; intercept = 0.14 cm2; slope = 1.00; and p = 0.0001) and TEE-VAX (r = 0.92; SEE = 0.36 cm2; intercept = 0.13 cm2; slope = 0.97; and p = 0.0001). These results are directly applicable to Doppler TEE in the determination of mitral stenosis area by pressure half-time, whereby 21% to 32% of patients using the horizontal or vertical transesophageal planes may have a significant angle of incidence leading to underestimation of transmitral valve velocities. Future studies comparing Doppler TEE with cardiac catheterization are of interest. However, the present study suggests that Doppler TEE will play an important role in the hemodynamic assessment of the severity of mitral valve stenosis.

Effects of Nifedipine and Nitroglycerin on Left Ventricular Systolic Dysfunction and Impaired Diastolic Filling After Exercise-Induced Ischemia in Humans

OBJECTIVES This study sought to determine whether calcium antagonist, compared with nitroglycerin, administration attenuates left ventricular dysfunction after exercise-induced ischemia in humans. BACKGROUND Exercise-induced ischemia impairs left ventricular systolic function and diastolic filling after exercise. The mechanism of this phenomenon is unknown but may relate to intracellular calcium overload. METHODS Echocardiography was performed in 131 patients before and 30 min, 2 h and 4 h after exercise stress test. Ischemia was defined as a reversible thallium stress defect. No medication, sublingual nitroglycerin or nifedipine was randomly given to each patient at peak exercise. RESULTS Isovolumetric relaxation time was significantly prolonged from rest (100 +/- 19 ms [mean +/- SD]) to 30 min (118 +/- 20 ms, p < 0.0005), 2 h (117 +/- 18 ms, p < 0.0005) and 4 h (110 +/- 22 ms, p < 0.05) after exercise in 21 patients with exercise-induced ischemia who received no medication (ischemia-none group). Isovolumetric relaxation time similarly increased after exercise in 23 patients who received nitroglycerin and had exercise-induced ischemia (ischemia-NTG group) but was unchanged in 20 patients with exercise-induced ischemia who received nifedipine (ischemia-nifedipine group). Peak early filling velocity decreased in the ischemia-none and ischemia-NTG groups from rest to 30 min and 2 h after exercise, but peak early filling velocity was unchanged in the ischemia-nifedipine group. Ejection fraction decreased from rest to 30 min after exercise in the ischemia-none group (59 +/- 12% vs. 51 +/- 13%, p < 0.025) and ischemia-NTG group (59 +/- 14% vs. 49 +/- 14%, p < 0.005) but was unchanged in the ischemia-nifedipine group (60 +/- 19% vs. 64 +/- 18%, p = NS). A new regional left ventricular wall motion abnormality occurred more frequently 30 min after exercise in the ischemia-none group (11 [52%] of 21) and ischemia-NTG group (9 [39%] of 23) compared with the ischemia-nifedipine group (2 [10%] of 20, both p < 0.05). No change occurred in left ventricular systolic function and diastolic filling after exercise in the control groups. CONCLUSIONS Exercise-induced ischemia impairs systolic function and diastolic filling after exercise. Sublingual nifedipine but not nitroglycerin attenuates this process and suggests that altered calcium homeostasis may play a role in left ventricular dysfunction that occurs after exercise-induced ischemia.