Phillip R. Dawkins

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.

The cough test is superior to the Valsalva maneuver in the delineation of right-to-left shunting through a patent foramen ovale during contrast transesophageal echocardiography

A patent foramen ovale may result in paradoxical embolization and serious morbidity. Thus a sensitive method to diagnose a patent foramen ovale is important. It is unknown whether the cough test or the Valsalva maneuver is superior in delineating right-to-left shunting through a patent foramen ovale during contrast transesophageal echocardiography. Thus we studied 73 consecutive patients (53 men and 20 women), aged 54 +/- 16 years (range 18 to 79 years), during elective transesophageal echocardiography. Contrast transesophageal echocardiography was performed from a four-chamber view during quiet respirations, Valsalva maneuver, and cough test. In the entire group the incidence of a patent foramen ovale was higher during the cough test (32/73) as compared with the Valsalva maneuver (24/73, p < 0.025) and quiet respirations (18/73, p < 0.005). All subjects with a patent foramen ovale during the Valsalva maneuver had a positive contrast transesophageal echocardiogram during the cough test. In subjects (n = 55) without a patent foramen ovale during quiet respirations, the incidence of a patent foramen ovale was higher during the cough test (15/55) as compared with the Valsalva maneuver (9/55, p < 0.05). In a subgroup (N = 17) of patients with nonhemorrhagic stroke (n = 11), transient ischemic attack (n = 2), or peripheral embolus (n = 4), the cough test had a higher yield (9/17) in delineating a patent foramen ovale as compared with the Valsalva maneuver (7/17) but did not reach statistical significance. These data demonstrate that the cough test is superior to the Valsalva maneuver in delineating a patent foramen ovale during contrast transesophageal echocardiography.(ABSTRACT TRUNCATED AT 250 WORDS)

Mobile strands are frequently attached to the St. Jude Medical mitral valve prosthesis as assessed by two-dimensional transesophageal echocardiography

Two-dimensional transesophageal echocardiographic findings are reported in 13 patients with structurally and functionally normal St. Jude Medical bileaflet mitral valve prostheses. Multiple mobile linear echogenic densities attached to the pivot of the prosthesis were present in 9 of 13 patients. These densities may represent fibrin strands. These mobile strands alternatively resolve and reform over a period of 5 to 14 months after mitral valve replacement. No adverse clinical events were attributable to these prosthetic mitral valve strands. We conclude that mobile stands are frequently attached to the structurally and functionally normal St. Jude Medical mitral valve prosthesis. The clinical significance of these prosthetic mitral valve strands requires clarification.

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)

Transesophageal echocardiography in the pregnant patient

conclusion of TPA treatment, aspirin and heparin therapy were started to prevent further thrombosis. Several days later, her regimen of daily doses of warfarin was resumed, and the heparin therapy was discontinued. The patient tolerated thrombolysis well, with no obvious side effects, and was transferred out of the intensive care unit on day 6. She was discharged on day 16, with no detectable signs of valvular dysfunction. Follow-up examinations 3 and 6 months later revealed no further signs of valvular thrombosis. We chose a lower dose of TPA, approximately l/10 to l/20 the usual adult acute dose, in an attempt to decrease the risk of bleeding and embolization of the thrombi through the patient’s ventricular septal defect. We felt that a continuous infusion would provide the optimum activation of the thrombolyt,ic pathway because it, would allow slow dissolution of the clots’ exposed surfaces and thus would help prevent embolization of a larger piece. The combination of continuous infusion and a half-life of 3 to 10 minutes would, we believed, allow us to terminate the process rapidly if bleeding or cerebral embolism occurred or if the therapy failed and an urgent operation was necessary. The prolonged half-life of streptokinase and urokinase make them less attractive for this reason. There are potentially serious risks associated with thrombolytic agents. There is an 0.4”,’ to 1“;) incidence of intracranial bleeding and as high as a 5”~’ incidence of other organ bleeding. Also, TPA is 10 to 20 times more expensive than the other thrombolyt,ic agents. Despite the potential problems of TPA, its use should be considered for the treatment of life-threatening thrombosis when other agents have failed or have caused allergic reactions, or when an urgent operation will be necessary should medical management fail. Medical management with TPA should only be attempted, however, in institutions where alternative medical and surgical therapies are available in case of emergency.

Transesophageal echocardiography: normal variants and mimickers.

An accurate diagnosis of cardiac pathology using TEE is contingent upon the ability to recognize and differentiate normal cardiac structures and normal variants from pathologic conditions. We describe several normal cardiac structures commonly imaged using TEE of the atria, interatrial septum, aorta, valves, and extracardiac spaces that may mimic diverse pathologic states, such as intracardiac tumor and thrombus, valvular vegetations, mitral and tricuspid valve prolapse, atherosclerotic plaque, and aortic dissection. Methods to aid in the differentiation of normal cardiac structures from pathology are offered.