Howard J. Ricketts

Left ventricular function following internal mammary inplantation

Abstract The effect of internal mammary arterial revascularization of the myocardium on left ventricular (LV) function was studied in 12 patients before and 11 to 24 months after operation by quantitative LV biplane angiocardiography and hemodynamics. An additional four patients who were not treated surgically were also studied. Preoperatively all were rated as clinical class II or III; all had moderate impairment of treadmill exercise tolerance; none had mitral regurgitation or heart failure. Seven had definite myocardial infarctions. Six received single and six double mammary implants. Prior to therapy, the average LV enddiastolic volume (EDV) was 71 ± 22 c.c. per square meter; the end-systolic volume (ESV) was 25 ± 20 c.c. per square meter; the systolic ejection fraction (SEF) was 68 ± 15; the LV mass (LVM) was 99 ± 26 Gm. per square meter; the LV pressure (LVP) was 9 mm. Hg; and the angiographic cardiac index (ACI) was 3.62 ± 0.4 L. per minute per square meter. Only one patient had abnormal contraction involving more than 25 per cent of the left ventricle. Following therapy clinical class improved in four, declined in five, and was constant in seven. None became Class I. A test of exercise capacity (functional aerobic impairment) showed an insignificant improvement from 39 ± 11 to 30 ± 18 per cent. Mitral regurgitation was present in one and heart failure in one. Underlying coronary artery lesions progressed in two and improved in one. LV studies showed EDV, 78 ± 25 c.c. per square meter; ESV, 34 ± 20 c.c. per square meter; SEF, 58 ± 16 per cent; LVP, 10 mm. Hg; and ACI, 3.40 ± 0.9 L. per minute per square meter. Contraction patterns had become worse in six of 15 patients, and none improved. In nine successful implants four showed good anastomoses and five minimal anastomosis with the coronary arterial bed. Stability or improvement in clinical class and exercise performance could not be related to improvement in LV function following myocardial revascularization; in fact, some patients had deterioration in LV function, suggesting that injury to the myocardium occurs at the time of operation.