Low dose dobutamine echocardiography in the assessment of contractile reserve to predict the outcome of valve replacement for chronic aortic regurgitation.

BACKGROUND: When to perform surgery for aortic regurgitation is a difficult clinical decision. Occult left ventricular (LV) dysfunction may be present in patients with minimal or no symptoms, and in some patients LV dysfunction may persist after valvular replacement. OBJECTIVES: To examine the role of preoperative low dose dobutamine echocardiography (LDDE) in predicting postoperative outcome in patients who had aortic valve replacement for aortic regurgitation. PATIENTS AND METHODS: The study group comprised 16 patients (15 men, aged 48 +/- 15 years) undergoing elective surgery for aortic regurgitation. Preoperative echocardiograms were obtained in the resting state and during dobutamine infusion at 7.5 micrograms/kg/min. Complete recovery was defined by normalization of LV size and function, and the absence of symptoms at the six-month follow-up visit. Patients with complete recovery (group 1) and without complete recovery (group 2) were compared in relation to their echocardiographic parameters at rest and during LDDE. RESULTS: Of 16 patients in the study, nine were in group 1 and seven were in group 2. Age, functional class and LV end-diastolic dimensions were similar between the two groups. Group 1 patients had a smaller preoperative LV end-systolic dimension index (22.4 +/- 3.3 versus 29.9 +/- 5.9 mm/m2, P < 0.05) and a higher preoperative ejection fraction (53 +/- 8% versus 37 +/- 13%, P < 0.01). Dobutamine infusion augmented the difference in ventricular size and function between patients in group 1 and those in group 2 (LV end-systolic dimension index 18.9 +/- 3.9 mm/m2 versus 28.8 +/- 7.1 mm/m2, P < 0.01; ejection fraction 61 +/- 7% versus 41 +/- 12%, P < 0.01). CONCLUSIONS: Dobutamine accentuates differences in ventricular size and function between those with and without subsequent complete recovery following valve surgery. Because preoperative ejection fraction during LDDE is highly predictive of postoperative ejection fraction, LDDE may have a role in predicting the clinical outcome of patients following aortic valve replacement for aortic regurgitation.

Inhaled nitric oxide reduction in systolic pulmonary artery pressure is less in patients with decreased left ventricular ejection fraction.

OBJECTIVE: To assess whether inhaled nitric oxide decreases pulmonary artery pressure in patients with depressed left ventricular ejection fraction. DESIGN: Randomized, blinded, crossover clinical trial. SETTING: Tertiary care university referral hospital. PATIENTS: Thirty-three patients with pulmonary hypertension and left ventricular dysfunction or valvular heart disease were recruited by convenience. INTERVENTIONS: Systolic pulmonary artery pressure was measured by Doppler echocardiography during randomized inhalation of either 20 ppm or 40 ppm nitric oxide in 30% oxygen as well as during control periods without nitric oxide. MAIN RESULTS: Systolic pulmonary artery pressure was significantly (P < 0.05) decreased with 20 ppm nitric oxide (53.4 +/- 13.9 mmHg) and 40 ppm nitric oxide (53.1 +/- 14.4 mmHg) compared with either initial control (55.8 +/- 15.3 mmHg) or terminal control (56.3 +/- 15.2 mmHg) values. The regression equation for the change in systolic pulmonary artery pressure (y) as predicted by the left ventricular ejection fraction (x) alone for 20 ppm nitric oxide was y = 13.8x-2.9; R2adj = 0.30, P < 0.0001. For 40 ppm nitric oxide alone, the regression equation was y = 16.3x-3.3; R2adj = 0.25, P < 0.0001. Left ventricular ejection fraction was the most explanatory independent variable in the multivariate equation for nitric oxide-induced change in systolic pulmonary artery pressure (R2 = 0.61, P = 0.0000). The change in systolic pulmonary artery pressure was -5.1 +/- 5.2 versus 0.8 +/- 4.9 mmHg (P < 0.0000) in patients with left ventricular ejection fractions greater than 0.25, and 0.25 or less, respectively. CONCLUSIONS: These data imply that in patients with left ventricular ejection fraction of 0.25 or less, nitric oxide may not decrease systolic pulmonary artery pressure. Nitric oxide inhalation may result in a paradoxical increase in systolic pulmonary artery pressure in patients with severely depressed left ventricular ejection fraction. This effect would significantly limit the therapeutic role of nitric oxide in patients with severe heart failure.

Transcranial Doppler ultrasonography and transesophageal echocardiography in the investigation of pulmonary arteriovenous malformation in a patient with hereditary hemorrhagic telangiectasia presenting with stroke.

BACKGROUND: Hereditary hemorrhagic telangiectasia (HHT) is associated with a high incidence of pulmonary arteriovenous malformations (PAVMs), which can be the underlying cause for cerebral ischemia or brain abscess. The diagnosis of these malformations may be difficult, as clinical or radiological findings may be absent. Transcranial Doppler ultrasound (TCD) with saline contrast and transesophageal echocardiography (TEE) with saline contrast are useful in identifying patients with right-to-left shunts and may help identify PAVMs. CASE DESCRIPTION: A 68-year-old woman with HHT presented with two strokes over a 1-year period. After the first stroke, a transthoracic echocardiogram with saline contrast demonstrated significant right-to-left shunt that was interpreted as a patent foramen ovale. After the second stroke, a TCD contrast study confirmed this right-to-left shunt; however, a TEE contrast study discovered an extracardiac shunt. Pulmonary angiography revealed a left lower lobe PAVM and three telangiectasias involving the right lung. The PAVM was subsequently embolized. Postembolization radiographic imaging showed complete occlusion of the feeding vessel to the PAVM. However, repeated contrast TCD and TEE demonstrated persistent right-to-left shunting. CONCLUSIONS: In our patient, stroke may have resulted from peripheral venous emboli passing through the PAVM or from endogenous thromboemboli originating within the PAVM. TCD and TEE contrast studies were helpful in judging the efficacy of catheter embolization therapy of PAVM. TCD and TEE with saline contrast may be clinically useful follow-up examinations for recurrence or development of new PAVMs.

Massive acute thrombosis of the descending thoracic aorta in heparin-associated thrombocytopenia and thrombosis.

Heparin-associated thrombocytopenia with thrombosis is a rare but serious complication in patients receiving heparin therapy. We report a case of a patient with this complication who had massive thrombosis within the descending thoracic aorta detected by transesophageal echocardiography. Our case suggests that a transesophageal echocardiographic examination can be useful in the early diagnosis of heparin-associated thrombocytopenia and thrombosis.

Congenitally bicuspid aortic valves: study of a variant with fenestrated raphe.

OBJECTIVE: To illustrate and describe a variant of the congenitally bicuspid aortic valve (BAV) in the context of previous reports of the morphology of BAVs. SETTING: Retrospective review of surgically excised aortic valves at The University of Ottawa Heart Institute in Ottawa, Ontario. DESIGN AND PATIENTS: The clinical, echocardiographic and pathological features of 17 cases with a variant of BAV were examined from patients who had valve replacements performed in the period from January 1, 1986 to December 31, 1992. MAIN RESULTS: A total of 865 patients had native aortic valve replacements during the study period and 291 patients had BAVs. One hundred and eighty-one patients were male (62%) (mean age 60 years) and 110 were female (38%) (mean age 64 years). There were 17 BAVs (6%) where either: the raphe was fenestrated so that only a thin fibrous band (or bands) joined the valve cusp to aortic wall-type A valves (seven cases); or a similar fibrous band (or bands) was seen, but was associated with other usual appearing raphal tissue--type B valves (10 cases). These patients included 15 males (mean age 63 years) and two females (mean age 63 years); they presented with dyspnea and/or angina. Distinction of the number of cusps with this variant was incorrect in six of nine transthoracic echocardiograms, and three of four transesophageal echocardiograms. CONCLUSION: This variant of BAV, with fenestrated raphe, is not well described in the literature, is difficult to diagnose clinically and may present in unusual ways.

Intractable ventricular arrhythmias during remodelling and healing after acute myocardial infarction.

A patient with extensive myocardial infarction, evidence of early ventricular remodelling, regional left ventricular (LV) dilation and aneurysm formation developed recurrent ventricular tachyarrhythmias and episodes of sudden death. The patient finally died 24 days post infarction despite effective anti-remodelling therapy and appropriate anti-failure and anti-arrhythmic therapies. Remarkable findings at autopsy included normal LV size and a small LV apical aneurysm despite as much as 52% LV necrosis and further right ventricular necrosis. The case underscores the need for aggressive early infarct-limiting therapy to prevent early remodelling, LV aneurysm and possibly fatal ventricular tachyarrhythmias.

Sudden death behind the wheel from natural disease in drivers of four-wheeled motorized vehicles.

The heart was studied in 30 persons who died suddenly from natural causes in the driver's seat of an automobile, truck or bus. Twenty had cardiac arrest while driving and the other 10 while sitting in the driver's seat of a parked vehicle. Of the 20 drivers, 16 died from atherosclerotic coronary artery disease (CAD): 12 (75%) had minor collisions and 4 did not. Of the 16 with fatal CAD, an average of 2.3 +/- 0.8 of the 4 major coronary arteries were narrowed greater than 75% in cross-sectional area (CSA) by plaque; of 668 five-mm segments of the 4 major (right, left main, left anterior descending, left circumflex) coronary arteries in 13 of these 16 cases, 27 (4%) were narrowed 96 to 100% and 127 (19%) were narrowed 76 to 95% in CSA by plaque. The remaining 4 drivers died from noncoronary conditions: aortic rupture associated with the Marfan syndrome in 1; cardiac sarcoidosis in 1; thoracic aortic dissection in 1; and severe mitral regurgitation from infective endocarditis, which had healed in 1. The other 10 persons were found dead in the driver's seat of a parked vehicle and 8 of them had fatal CAD. Of the 8 CAD victims, an average of 2.5 +/- 1.2 of the 4 major coronary arteries was narrowed greater than 75% by plaque; of the 283 five-mm segments of coronary arteries in 7 of the 8 cases, 44 (16%) were narrowed 96 to 100% and 69 (24%) were narrowed 76 to 95% in CSA by plaque.(ABSTRACT TRUNCATED AT 250 WORDS)