Internal mammary artery implant. A method for assessing the physiologic efficacy of the "Vineberg procedure"

Acute electrical stimulation increases extramyocardial collateral blood flow after a cardiomyoplasty

We hypothesized that acute electrical stimulation of a latissimus dorsi cardiomyoplasty would augment the collateral blood flow delivered by the skeletal muscle to the heart. This hypothesis was tested in an animal model (13 goats) of coronary artery disease. Six weeks after a cardiomyoplasty was performed, myocardial collateral blood flow derived from the latissimus dorsi muscle was measured with colored microspheres when the muscle was at rest and during electrical stimulation of the thoracodorsal nerve at 1.25 Hz. The area at risk for ischemia averaged 13.37 +/- 2.08 g (mean +/- standard error), or 18.4% of left ventricular mass (n = 13). At rest, significant skeletal muscle-derived collaterals developed in 9 animals, and formed predominantly to chronic ischemic myocardium (mean +/- standard error, 0.07 +/- 0.02 mL.g-1 x min-1; n = 9), rather than infarct (0.03 +/- 0.02 mL.g-1 x min-1; n = 5), or normal myocardium (0.0005 +/- 0.0001 mL.g-1 x min-1; n = 9). Stimulation increased skeletal muscle-derived collateral blood flow to chronic ischemic areas to 0.38 +/- 0.09 mL.g-1 x min-1 (n = 9) (p < 0.05). During stimulation, the collateral flow was greater in the epicardium (0.46 +/- 0.11 mL.g-1 x min-1) than in endocardium (0.14 +/- 0.09 mL.g-1.min-1) (p < 0.05). This study demonstrates that electrical stimulation of a latissimus dorsi cardiomyoplasty increases extramyocardial collateral blood flow to chronic ischemic myocardium.

Stress electrocardiography in the evaluation of surgical revascularization of the heart

Electrocardiography was carried out during hypoxemia and graded exercise tests before and at intervals between 2 and 20 months after attempts to revascularize the heart by internal mammary artery implantation in 44 patients with angiographically documented coronary disease and angina pectoris. Eleven patients had single vessel disease; the right coronary was involved in seven of these patients. Thirteen patients had single vessel implants, employing the left internal mammary artery in 11 patients and a saphenous vein graft from the aorta in two. Thirty-one patients had double internal mammary artery implantation accompanied by gastroepiploic arterial implantation in four.

Fifty per cent of the patients were symptomatically improved after surgery, the best results occurring in two patients with isolated anterior descending coronary disease. Of the 34 patients having postoperative coronary and mammary arteriography, 15% showed improvement which could be ascribed to mammary revascularization; 24% had limited myocardial revascularization and no symptomatic improvement; 29% had patent implants without development of collateral vessels, and the implanted vessels were occluded in 32%. Eleven of the 34 (32%) had fair or good symptomatic improvement in the absence of revascularization.

The results of postoperative stress electrocardiography correlated closely with the findings on postoperative coronary and mammary angiography. The stress tests were persistently positive after operation in 83% of the patients having angiographically confirmed implant occlusion or nonrevascularization. The stress ECG response was reversed, becoming negative postoperatively, in five cases of angiographically proved significant revascularization. Thus, stress electrocardiography provided objective evidence of improvement in a small number of patients with limited coronary disease who developed good collateral circulation and correlated with the lack of revascularization in the majority even in those subjectively improved.