Coronary artery bypass grafting in patients with chronic congestive heart failure: a 10-year experience with 203 patients

From 1983 to 1992, 203 patients with chronic congestive heart failure and no angina underwent primary coronary artery bypass. This represented 3% of patients undergoing coronary artery bypass grafting. Ninety-two percent of the patients were in New York Heart Association (NYHA) functional class III or IV prior to undergoing coronary artery bypass grafting. Thallium perfusion imaging was performed in 21% of the patients, with a reversible defect present in 88%. An internal mammary artery graft was used in 70% of the patients. The hospital mortality was 6.0% and the actuarial survival at 5 years was 59%. An improvement in NYHA functional class occurred in 75% of the surviving patients with a mean improvement of 1.6 +/- 0.6 functional classes. Univariate analysis identified risk factors for hospital death as emergency operation, recent myocardial infarction (< 30 days), and the need for an intra-aortic balloon pump. A trend emerged for nonuse of an internal mammary artery to predict hospital death. A positive thallium perfusion scan was not a predictor of early or late survival, nor did it influence NYHA functional class. The use of the internal mammary artery significantly enhanced late survival (p = 0.01), however, did not affect the functional class of survivors. We conclude that coronary artery bypass grafting is effective in ameliorating symptoms of chronic congestive heart failure in patients suffering from chronic ischemic cardiomyopathy and can be performed with acceptable early and late mortality.

The small aortic root and the Medtronic Hall valve: ultrafast computed tomography assessment of left ventricular mass following aortic valve replacement

BACKGROUND AND AIMS OF THE STUDY

The selection of an appropriate size aortic valve substitute with respect to patient size and life-style, in the presence of a small aortic root, is problematic, and a decision to enlarge the aortic annulus is often arbitrary. An aortic valve substitute-patient mismatch may place an excessive load on the left ventricle resulting in residual left ventricular mass with attendant patient morbidity and mortality. The aim of this study was to assess the adequacy of the Medtronic Hall valve in the small aortic root using ultrafast computed tomography analysis of left ventricular mass.

MATERIALS AND METHODS

In 13 patients the smallest Medtronic Hall valves (size 20 and 21; measured internal orifice area of 2.01 cm2 for both) were used to replace the native aortic valve. All patients had aortic stenosis, and left ventricular hypertrophy was established by echocardiography. The mean body surface area was 1.8 +/- 0.2 m2 (range 1.50-2.06 m2) and the mean weight was 75 +/- 15 Kg (range 50-97 Kg). The mean preoperative New York Heart Association functional class was 3.54 +/- 0.5.

RESULTS

There was no operative or late mortality. At a mean follow up of 22 months after aortic valve replacement, the mean left ventricular mass index was 89 +/- 11.4 g/m2 (normal left ventricular mass index by ultrafast computed tomography = 97 +/- 14 g/m2) and mean New York Heart Association functional class was 1.6 +/- 0.8 (p (Binomial) = 0.0001 compared to preoperative). Doppler echocardiogram demonstrated a mean gradient across the prosthetic valve of 17 +/- 7 mmHg. There was no trend towards greater left ventricular mass index in patients with greater body surface area or weight. In no patient was the aortic annulus enlarged.

CONCLUSIONS

Trends from this preliminary data suggest that implanting the smallest Medtronic-Hall aortic valves (sizes 20 and 21) results in normal left ventricular mass following aortic valve replacement in patients up to a body surface area of 2.06 m2 and provides support for the notion that an aortic annulus enlarging procedure was not necessary in this group of patients.

Normothermic retrograde cardioplegia is effective in patients with left ventricular hypertrophy. A prospective and randomized study

Twenty patients with left ventricular hypertrophy (LVH) undergoing isolated aortic valve replacement were prospectively randomized to receive either continuous retrograde normothermic (n = 8) or intermittent retrograde hypothermic (n = 12) methods of myocardial protection. Biopsies of the left ventricular septum were evaluated for ultrastructure and assayed for ATP. There was no mortality, no requirement for intra-aortic balloon pump nor neurological events in any of the patients from either group. Myocardial ATP (warm 23.2 +/- 1.8 nmol/mg protein; cold 22.4 +/- 1.2 nmol/mg protein; p = 0.72) and myocardial CPK-MB (warm 43.6 +/- 5.2 U/l; cold 39.0 +/- 2.5 U/l; p = 0.67) were not significantly different. Ultrastructure was generally well preserved in the biopsies from both groups, with the exception of one patient in the normothermic group. Systemic lactate sampled after 40 minutes of cardiopulmonary bypass was significantly higher in the normothermic group (warm 3.4 +/- 0.27 mmol/l; cold 2.3 +/- 0.21 mmol/l; p = 0.01), however, the myocardial lactate production was not significantly different between the two groups (extraction ratio; warm 0.01 +/- 0.3; cold 0.13 +/- 0.1; p = 0.45). We conclude that the continuous normothermic retrograde method of myocardial protection is effective in patients with left ventricular hypertrophy; however, the higher systemic lactate levels using this technique raises concerns regarding the adequacy of systemic perfusion at 37 degrees C.