Delayed preconditioning-mimetic action of nitroglycerin in patients undergoing coronary angioplasty.

BACKGROUND: Experimental studies suggest that the cardioprotective effects of the late phase of ischemic preconditioning (PC) can be mimicked pharmacologically. However, to date, no drug has been tested with respect to its ability to elicit a late PC effect in humans. As a consequence, clinical exploitation of the powerful anti-stunning and anti-infarct actions of late PC has been elusive thus far. METHODS AND RESULTS: A total of 66 patients were randomized to receive a 4-hour intravenous infusion of nitroglycerin (NTG) or normal saline; on the following day, they underwent percutaneous transluminal coronary angioplasty (three 2-minute balloon inflations 5 minutes apart). Measurements of ST-segment shifts (intracoronary and surface ECGs), regional wall motion (quantitative 2D echocardiography), and chest pain score indicated that the infusion of NTG 24 hours before angioplasty rendered the myocardium relatively resistant to ischemia and that the degree of this cardioprotective effect was comparable to that afforded by the ischemia associated with the first balloon inflation in control subjects (early phase of ischemic PC). Collateral flow (estimated from a pressure-derived index) did not differ between control and NTG-pretreated patients, indicating that the enhanced tolerance to ischemia in NTG-pretreated patients cannot be accounted for by baseline differences in collateral function. CONCLUSIONS: NTG protects human myocardium against ischemia 24 hours after its administration. To the best of our knowledge, this is the first report that a late PC effect can be recruited pharmacologically in humans. The results suggest that prophylactic administration of nitrates could be a novel approach to the protection of the ischemic myocardium in patients.

Use of transesophageal echocardiography to guide cardioversion in patients with atrial fibrillation.

BACKGROUND: The conventional treatment strategy for patients with atrial fibrillation who are to undergo electrical cardioversion is to prescribe warfarin for anticoagulation for three weeks before cardioversion. It has been proposed that if transesophageal echocardiography reveals no atrial thrombus, cardioversion may be performed safely after only a short period of anticoagulant therapy. METHODS: In a multicenter, randomized, prospective clinical trial, we enrolled 1222 patients with atrial fibrillation of more than two days' duration and assigned them to either treatment guided by the findings on transesophageal echocardiography or conventional treatment. The composite primary end point was cerebrovascular accident, transient ischemic attack, and peripheral embolism within eight weeks. Secondary end points were functional status, successful restoration and maintenance of sinus rhythm, hemorrhage, and death. RESULTS: There was no significant difference between the two treatment groups in the rate of embolic events (five embolic events among 619 patients in the transesophageal-echocardiography group [0.8 percent]) vs. three among 603 patients in the conventional-treatment group [0.5 percent], P=0.50). However, the rate of hemorrhagic events was significantly lower in the transesophageal-echocardiography group (18 events [2.9 percent] vs. 33 events [5.5 percent], P=0.03). Patients in the transesophageal-echocardiography group also had a shorter time to cardioversion (mean [+/-SD], 3.0+/-5.6 vs. 30.6+/-10.6 days, P<0.001) and a greater rate of successful restoration of sinus rhythm (440 patients [71.1 percent] vs. 393 patients [65.2 percent], P=0.03). At eight weeks, there were no significant differences between the two groups in the rates of death or maintenance of sinus rhythm or in functional status. CONCLUSIONS: The use of transesophageal echocardiography to guide the management of atrial fibrillation may be considered a clinically effective alternative strategy to conventional therapy for patients in whom elective cardioversion is planned.

Risk of thromboembolism in acute atrial fibrillation or atrial flutter.

Atrial fibrillation (AF) is the most common sustained cardiac dysrhythmia, predominating in the elderly, with stroke as a potentially devastating complication. Prevention of the thromboembolic sequelae from AF remains a central focus of practicing clinicians. Although the risk of thromboembolism in chronic AF is well recognized, less is known about the potential risk of systemic embolism in acute AF. In addition, recent data support the notion of a group at considerable risk of embolism from atrial flutter, an arrhythmia typically believed to bestow little increased risk of thromboembolism. The mechanism of thrombus formation, embolization, and resolution in atrial arrhythmias is not well defined, particularly in that of acute AF or atrial flutter. The traditional concept proposes that atrial thrombus forms only after > 2 days of AF and embolizes by being dislodged from increases in shear forces. This widely accepted concept further holds that newly formed atrial thrombus, in the setting of AF, organizes over a span of 14 days. The results of studies based on observations from transesophageal echocardiography examinations have provided provocative insight into the temporal sequence of atrial thrombus formation, embolization, and resolution in AF or atrial flutter and have expanded the traditional concept of thromboembolism in these atrial dysrhythmias. Namely, left atrial thrombus may form before the onset of AF in the face of sinus rhythm. Conversion to sinus rhythm may increase the thrombogenic milieu of the left atrium. Importantly, atrial thrombus may form in the acute phase of AF. Last, thrombi may require > 14 days to become immobile or to resolve. Findings similar to those of acute AF have been reported in patients with atrial flutter and coexisting cardiac pathology. On the basis of these emerging insights fostered by the use of transesophageal echocardiography, it appears appropriate to consider anticoagulation in patients presenting with acute AF or atrial flutter with coexisting cardiac pathology predisposing to left atrial thrombus.

Transesophageal echocardiography guided enoxaparin antithrombotic strategy for cardioversion of atrial fibrillation: the ACUTE II pilot study.

BACKGROUND: Patients with atrial fibrillation >2 days' duration for whom immediate cardioversion is desired or required are commonly hospitalized for 4 or more days of antithrombotic therapy with intravenous unfractionated heparin and commencement of oral warfarin. For these early cardioversion patients, self-administered low-molecular-weight heparin (enoxaparin sodium) as "bridge" therapy to warfarin may obviate the need for hospitalization and activated partial thromboplastin time monitoring and thus potentially lower costs and enhance utility. OBJECTIVE: To compare feasibility and safety of a transesophageal echocardiography (TEE)-guided enoxaparin strategy with those of a TEE-guided unfractionated heparin strategy in patients with atrial fibrillation of >2 days' duration undergoing early electrical or chemical cardioversion. DESIGN AND SETTING: This is a randomized, multicenter clinical trial at 11 hospitals in the United States. PATIENTS AND INTERVENTION: Two hundred patients with atrial fibrillation >2 days' duration requiring early chemical or electric cardioversion will be enrolled. TEE-guided intravenous unfractionated heparin bridge therapy will be compared with TEE-guided subcutaneous enoxaparin bridge therapy. OUTCOME MEASURES: Feasibility outcomes are time to hospital discharge, patient quality of life/utility, treatment costs, and sinus rhythm. Safety outcomes are ischemic stroke, transient ischemic attack, systemic embolization, major and minor bleeding, clinical hemodynamic instability, and cardiac and cardioversion-related death for a 5-week period from enrollment. CLINICAL IMPLICATIONS: The results of this pilot study will have important clinical and economic implications for the antithrombotic management of patients with atrial fibrillation undergoing TEE-guided cardioversion.

Bradykinin-induced preconditioning in patients undergoing coronary angioplasty.

OBJECTIVES: The purpose of this study was to determine whether administration of bradykinin reproduces the cardioprotective effects of ischemic preconditioning (PC) in patients undergoing percutaneous transluminal coronary angioplasty (PTCA). BACKGROUND: Experimental studies suggest that activation of the bradykinin B2 receptor is an important trigger of ischemic PC. However, it is unknown whether bradykinin can precondition human myocardium against ischemia in vivo. Multicenter clinical trials have demonstrated an anti-ischemic effect of angiotensin-converting enzyme inhibitors, which has been postulated to result from potentiation of bradykinin; however, direct evidence for an anti-ischemic action of bradykinin in patients is lacking. METHODS: Thirty patients were randomized to receive a 10-min intracoronary infusion of bradykinin (2.5 microg/min) or normal saline. Ten minutes later they underwent PTCA (three 2-min balloon inflations 5 min apart). RESULTS: In control patients, the ST-segment shift on the intracoronary and surface electrocardiogram was significantly greater during the first inflation than during the second and third inflations, consistent with ischemic PC. In bradykinin-treated patients, the ST-segment shift during the first inflation was significantly smaller than in the control group, and there were no appreciable differences in ST-segment shift during the three inflations. Measurements of chest pain score and regional wall motion during inflation (quantitative two-dimensional echocardiography) paralleled those of ST-segment shift. Infusion of bradykinin had no hemodynamic effects and no significant adverse effects. Thus, intracoronary infusion of bradykinin before PTCA rendered the myocardium relatively resistant to subsequent ischemia, and the degree of this cardioprotective effect was comparable to that afforded by the ischemia associated with the first balloon inflation in control subjects. In a separate cohort of seven patients given the same dose of bradykinin, coronary hyperemia resolved completely within 10 min after the end of the infusion, indicating that bradykinin-induced vasodilation cannot account for the protective effects observed during the first balloon inflation. CONCLUSIONS: Bradykinin preconditions human myocardium against ischemia in vivo in the absence of systemic hemodynamic changes. Pretreatment with bradykinin appears to be just as effective as ischemic PC and could be used prophylactically to attenuate ischemia in selected patients undergoing PTCA.

Comparison of MPEG digital video with super VHS tape for diagnostic echocardiographic readings.

BACKGROUND: Digital recording of echocardiographic studies is on the clinical horizon. However, full digital capture of complete echocardiographic studies in traditional video format is impractical, given current storage capacity and network bandwidth. To overcome these constraints, we evaluated the diagnostic image quality of digital video by using MPEG (Motion Picture Experts Group) compression. METHODS AND RESULTS: Fifty-eight complete, consecutive studies were recorded simultaneously with the use of MPEG-1 and sVHS videotape. Each matched MPEG and sVHS study pair was reviewed by two from a total of six readers, and findings were recorded with the use of a detailed, computerized reporting tool. Intrareader and interreader discrepancies were characterized as major or minor and analyzed in total and for specific subgroups of findings (left and right ventricular parameters, valvular insufficiency, and left ventricular regional wall motion). Intrareader discrepancies were reviewed by a consensus panel for agreement with either MPEG or sVHS findings. There was an exact concordance between MPEG and sVHS readings in 83% of findings. The majority of discrepancies were minor, with major discrepancies in only 2.7% of findings. There was no difference in the rate of consensus panel agreement with MPEG or sVHS for instances of intrareader discrepancy, either in total or for any subgroup of findings. Interreader discrepancy rates were nearly identical for both MPEG and sVHS. CONCLUSIONS: MPEG-1 digital video is equivalent to sVHS videotape for diagnostic echocardiography. MPEG increases the range of practical options for digital echocardiography and offers, for the first time, the advantages of digital recording in a familiar video format.

Patent foramen ovale presenting as refractory hypoxemia after heart transplantation.

Hypoxemia can be an early life-threatening complication of orthotopic heart transplantation. Commonly, hypoxemia after orthotopic heart transplantation is due to pulmonary hypertension or pulmonary complications. Rarely, structural defects either in the donor or recipient heart can lead to life-threatening hypoxemia. This case illustrates hypoxemia after orthotopic heart transplantation caused by the development of a right-to-left shunt through a patent foramen ovale in the recipient which had preoperatively been hemodynamically insignificant. The refractory hypoxemia required emergency surgical correction of the patent foramen ovale within the first postoperative week. In addition, this case illustrates the unique application of different methods of echocardiograms providing noninvasive diagnosis of structural defects in orthotopic heart transplantation.

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.

Doppler transesophageal echocardiographic determination of aortic valve area in adults with aortic stenosis.

Two-dimensional transesophageal echocardiography has been shown to be an accurate method of measuring aortic valve area in patients with aortic stenosis. The accuracy of Doppler transesophageal echocardiography for this purpose is unknown. Thus 86 consecutive adult patients (mean age 68 +/- 11 years) with calcific (n = 79) or congenital bicuspid (n = 7) AS were studied by biplane or multiplane transesophageal echocardiography. From the transgastric long-axis view, continuous wave Doppler of peak aortic valve velocity and pulsed Doppler of left ventricular outflow tract velocity were determined. Left ventricular outflow tract diameter was measured from a transesophageal echocardiography long-axis view, and cross-sectional area was calculated. Aortic valve area was calculated by the continuity equation. Two-dimensional transesophageal echocardiography was used to directly measure aortic valve area by planimetry of the minimal orifice from a short-axis view. Aortic valve area determination was less feasible by Doppler (62 of 86 patients, or 72%) versus two-dimensional transesophageal echocardiography (81 of 86 patients, or 94%; p < 0.0025) because of the inability to align the continuous wave Doppler beam with the aorta in 24 patients. The feasibility of obtaining aortic valve area by Doppler transesophageal echocardiography improved from the first 43 patients (24 of 43 patients, or 56%) to the latter 43 patients (38 of 43 patients, or 88%; p < 0.0025) and suggests a significant learning curve. In 62 patients, aortic valve area by Doppler and two-dimensional transesophageal echocardiography did not differ (1.30 +/- 0.54 cm2 vs 1.23 +/- 0.46 cm2, p = not significant) and correlated well (r = 0.88; standard error of the estimate = 0.26 cm2; intercept = 0.02 cm2; slope = 1.04; p = 0.0001). Absolute and percent differences between aortic valve area measured by Doppler and two-dimensional transesophageal echocardiography were small (0.18 +/- 0.20 cm2 and 15% +/- 15%, respectively). Mild, moderate, and severe aortic stenosis by two-dimensional transesophageal echocardiography was correctly identified in 93% (28 of 30), 79% (15 of 19), and 77% (10 of 13) of patients by Doppler transesophageal echocardiography, respectively. Doppler transesophageal echocardiography is an accurate method to measure aortic valve area in patients with aortic stenosis and should complement two-dimensional transesophageal echocardiography. The feasibility of Doppler transesophageal echocardiography for aortic valve area determination has a significant learning curve.

Risk of thromboembolism in new onset or transient atrial fibrillation.

Atrial fibrillation (AF), potentially serious cardiac arrhythmia, occurs in 2% to 4% of persons greater than 60 years of age. The risk of systemic thromboembolism from chronic AF has long been recognized. Little is known about the thromboembolic risk of new onset AF. However, the results of prior studies support a significant risk of thromboembolism because of recent onset or paroxysmal AF. The mechanism of thrombus formation, embolization, and resolution in AF is ill-defined, particularly that of new onset. The traditional concept holds that atrial thrombus forms only after greater than 2 days of AF and embolizes by dislodgement from increases in shear forces. This prevailing concept further proposes that newly formed atrial thrombus, in the setting of AF, organizes over a span of 14 days. The results of recent transesophageal echocardiographic studies have given insight into the temporal sequence of atrial thrombus formation, embolization, and resolution in AF and have expanded the traditional concept of thromboembolism in AF. Namely, left atrial thrombus may form before the onset of AF in the face of sinus rhythm. Conversion to sinus rhythm may increase the thrombogenic millieu of the left atrium. Importantly, atrial thrombus may form in the acute phase of AF. Lastly, thrombus may require more than 14 days to become immobile or to resolve. On the basis of these emerging insights by transesophageal echocardiography, it appears appropriate to consider anticoagulation in patients presenting with new onset or acute AF.

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.

Diastolic dysfunction is a feature of the antiphospholipid syndrome.

Recurrent thrombi, thrombocytopenia, pregnancy loss, and stroke in association with medium to high concentrations of anticardiolipin antibodies are well-recognized features of antiphospholipid syndrome. Cardiac manifestations of primary antiphospholipid syndrome (PAPS) also have been documented but involve structural and valvular heart disease. Diastolic dysfunction in PAPS has not been well described. Therefore, 10 patients with PAPS (nine women and one man) of mean age 30 +/- 7 years (range 20 to 46 years) and 10 healthy age-, sex-, weight-, and height-matched control subjects were studied by echocardiography. Anticardiolipin antibody concentrations of patients with PAPS were > 80 immunoglobulin G phospholipid units as determined by enzyme-linked immunosorbent assay. Doppler-derived parameters of left ventricular filling showed a significant association between PAPS and diastolic dysfunction compared with control, as evidenced by a decrease in peak early filling velocity (52 +/- 10 cm/sec vs 67 +/- 12 cm/sec; p < 0.01), a decrease in the ratio of peak early to peak atrial filling velocities (1.03 +/- 0.40 vs 1.52 +/- 0.28; p < 0.005), a decrease in the mean deceleration rate of early filling (338 +/- 75 cm/sec2 vs 590 +/- 227 cm/sec2; p < 0.005), and an increase in the percentage of atrial contribution to filling and deceleration time. Left ventricular mass, diastolic filling time, and heart rate did not differ between groups. Left ventricular systolic function was normal and ejection fraction did not differ between patients with PAPS and control subjects (63% +/- 2% vs 65% +/- 7%; p not significant).(ABSTRACT TRUNCATED AT 250 WORDS)

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.

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.

Left atrial appendage thrombus is not uncommon in patients with acute atrial fibrillation and a recent embolic event: a transesophageal echocardiographic study.

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 > or = 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.

Intravascular ultrasound imaging of a patent ductus arteriosus in an adult.

A small patent ductus arteriosus (PDA) is compatible with a normal life span. A non-restrictive PDA may present with signs of heart failure, supraventricular arrhythmia's, bacterial endocarditis or endarteritis later in life. Fewer than 50% of patients, including those with small shunts, are symptomatic by the age of 50. Considering that 40% of patients with PDA's will die before the age of 45 as a result of bacterial endocarditis or heart failure, closure of the PDA is recommended. Exceptions are patients with a nondilated heart, a right-to-left shunt, or age greater than 60 years old. Because of the wider use of echocardiography, especially transesophageal echocardiography, many PDA's are now detected incidentally in patients without symptoms.

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)

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.

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.