Enhanced transcardiac l-norepinephrine response during cold pressor test in obstructive coronary artery disease.

An increase in cardiac sympathetic activity can enhance coronary vasomotor tone and lower the ventricular fibrillation threshold. We compared the transcardiac l-norepinephrine responses during cold pressor test of 20 patients with normal coronary arteries with those of 23 patients with obstructive coronary artery disease. Baseline hemodynamic data did not differ in the 2 patient groups except for left ventricular end-diastolic pressures; mean values (+/- standard deviation [SD] were 10 +/- 3.7 and 15 +/- 4.5 mm Hg in patients with normal and abnormal coronary arteries (p less than 0.01). Baseline l-norepinephrine contents averaged 295 +/- 152 (normal coronary arteries) and 250 +/- 134 pg/ml (coronary artery disease) in the arterial blood, and 273 +/- 152 and 250 +/- 115 pg/ml, respectively, in the coronary sinus blood. Hemodynamic responses during cold stimulus were similar in both groups. Also, cold pressor-induced increases in arterial and coronary sinus l-norepinephrine contents were balanced in patients with normal coronary arteries, averaging 19 +/- 30 and 17 +/- 37%, respectively. In patients with coronary artery disease, however, a 26 +/- 58% increase in arterial l-norepinephrine contents was associated with a 58 +/- 62% increase in coronary sinus l-norepinephrine contents (p less than 0.02), suggesting myocardial l-norepinephrine net release. It is concluded that transcardiac l-norepinephrine responses during cold stimulus are enhanced in patients with obstructive coronary artery disease. This response to a relatively mild sympathetic stress, reproducible by a variety of analogous stressful situations during daily life, could present an increased risk for acute cardiac events.

Revascularization of the right coronary artery.

This study was undertaken to evaluate revascularization of the right coronary artery with regard to factors that enter into the decision to graft less significant lesions, such as graft flow, graft patency and progression of proximal disease. The results of grafting the right coronary artery were studied in 23 patients with lesions reducing luminal diameter by less than 50 percent (Group 1), 35 patients with luminal narrowing of 50 to 70 percent (Group 2) and 112 patients with greater than 70 percent luminal narrowing (Group 3). At operation there was no significant difference in saphenous vein graft flows among the three groups. Postoperatively the mean follow-up period was 20, 27 and 26 months, respectively. Graft patency was not significantly different among the three groups. Progression of the proximal lesion was studied and compared with that in 71 ungrafted right coronary arteries, 60 with less than 50 percent stenosis and 11 with more than 50 percent stenosis. Among vessels with less than 50 percent narrowing, the proximal lesion showed progression in 26 percent of the ungrafted vessels and in 83 percent of the grafted vessels (P less than 0.005); progression to total occlusion occurred in 3 percent of the former and in 28 percent of the latter (P less than 0.005). Progression to total occlusion was more frequently associated with a patent than with an occluded graft (P less than 0.05). The occurrence of significant progression in ungrafted vessels and the lack of effect on graft patency of the severity of the proximal disease suggest that revascularization of less significant lesions may be of value. However, the resultant increase in progression of proximal disease makes the patient dependent on the long-term patency of the vein graft.

Long-term effect of the superior vena cava-pulmonary artery anastomosis on pulmonary blood flow.

The long-term effects of the superior vena cava-pulmonary artery anastomosis were evaluated in 15 patients a mean of 8.5 years postoperatively. There were eight patients with tricuspid atresia and seven with other complex anomalies. Ten patients underwent 133xenon ventilation scans and 99mtechnetium perfusion scans in the upright and suprine positions. Perfusion scans showed decreased perfusion of the right upper lobe which improved in the supine position. Shunt flow, measured by thermodilution in nine patients, was a mean of 1.7 L. per minute per square meter, with a mean superior vena caval pressure of 8 mm. Hg and a resistance of 3.0 units. Right and left pulmonary venous saturations were 94 and 96 percent, respectively, showing little intrapulmonary shunting. Venous collaterals were the major cause for shunt failure. Six patients underwent a left Blalock-Taussig shunt and division of venous collaterals a mean of 6 years after the Glenn shunt and are all doing well. The superior vena cava-pulmonary artery anastomosis did not result in progressive pulmonary deterioration in the patients studied. The staged treatment of tricuspid atresia by the Glenn shunt followed by a systemic-pulmonary artery shunt and ligation of venous collaterals gives prolonged effective palliation.

Multivariate discriminant analysis of the clinical and angiographic predictors of operative mortality from the Collaborative Study in Coronary Artery Surgery (CASS).

The Collaborative Study in Coronary Artery Surgery (CASS) is a large multi-institutional study of the medical and surgical treatment of coronary artery disease (CAD). Fifteen cooperating institutes have carried out isolated coronary artery bypass grafting (CABG) on 6,176 patients from August, 1975, through December, 1978. The operative mortality (OM) was 2.3%. In an effort to better understand the clinical and angiographic characteristics predictive of OM, we have done a multivariate discriminant analysis of variables associated with OM. Numerous clinical and angiographic variables were selected from the CASS data file and evaluated in a univariate manner for their relationship to OM. Twenty of these variables were then selected for multivariate discriminant analysis. Clinical variables of most predictive value were age, female sex, increased heart size, and congestive heart failure (CHF). Angiographic variables of importance included left ventricular wall motion abnormalities, and left main coronary disease (LMCD). The priority of operation (elective, urgent, or emergent) was also associated with OM. Six variables that contained the most predictive information were selected by discriminant analysis for a group of 6,176 patients who had isolated bypass operations. In descending order of importance they were age, left main coronary artery stenosis greater than or equal to 90%, female sex, left ventricular wall motion score, left ventricular end-diastolic pressure (LVEDP), and râles. Five other groups or subgroups of patients were also analyzed in a similar manner. There is a strong association of OM with advanced age, female sex, and variables associated with left ventricular dysfunction. The risk of OM for an individual patient may be estimated with the use of these clinical and angiographic characteristics.

Operative flow measurements and coronary bypass graft patency.

Early (one week) and late (one year) postoperative angiography was performed in 142 patients having 310 grafts (117 right coronary artery [RCA], 134 left anterior descending [LAD], and 59 circumflex coronary artery [CCA]) to assess the factors responsible for failure of aorta-coronary artery saphenous vein grafts. Early catheterization revealed an 85.5 per cent patency rate with similar rates for each artery (RCA 88 per cent, LAD 85 per cent, and CCA 81 per cent). At one year 238 grafts remained patent, for a cumulative patency rate of 76.8 per cent with a similar distribution for each vessel (RCA 75 per cent, LAD 78 per cent, and CCA 76 per cent). Intraoperative flow measurements were correlated with early and late patency. Grafts with a basal flow less than 20 ml. per minute have a 42 per cent early closure rate and a 21 per cent late closure rate (cumulative 63 per cent). A basal flow of less than 40 ml. per minute was associated with a 25 per cent early failure and an 11 per cent late failure rate (cumulative 36 per cent). Basal flow at levels greater than 40 ml. per minute was not associated with an increased probability of graft closure. Absence of reactive hyperemia (30 second graft occlusion) was associated with a 19 per cent probability of early closure and a 31 per cent probability of cumulative thrombosis. A papaverine-induced flow increase (15 mg. given into the graft) of less than 100 per cent over basal flow gave a 20 per cent probability of early failure and 30 per cent probability of cumulative closure. Thus intraoperative basal flow measurements are of predictive value in determining the fate of aorta-coronary artery vein bypass grafts, and vasodilatory maneuvers provide little additional information.

Nonsyphilitic coronary ostial stenosis.

From October 1970 to June 1977, a total of 15 patients (12 women) were seen with atherosclerotic coronary ostial stenosis (14 left, one right). All patients had angina and two had aortic valve disease. Additional coronary arterial disease was present in nine. One patient declined surgery and died four months later after myocardial infarction. All patients had coronary bypass grafts and two had aortic valve replacement. One patient with valve replacement and one with preoperative cardiogenic shock died postoperatively. Angina recurred nine months postoperatively in one patient; the others (11) are free of angina. Postoperative catheterization from two weeks to 4.5 years in ten of 12 showed 11 of 13 vein grafts and eight of nine internal mammary artery grafts to be patent. In three patients, only a single left-sided coronary bypass was placed to the left anterior descending artery, because the circumflex branches were too small. Ideally, two left-sided bypass grafts should be placed for left ostial disease.

Late patency of the internal mammary artery as a coronary bypass conduit.

From January, 1972, through August, 1977, 472 patients had internal mammary artery (IMA) coronary bypass, of which 100 were double-IMA bypasses. We selected those patients having a widely patent IMA one year postoperatively who then had a second catheterization 49 to 105 (mean, 64) months following operation. None of the 93 patients who met these criteria was specifically recalled for this study; they all had follow-up catheterizations for multiple other reasons. All of the 91 left IMA and 22 right IMA bypasses (total, 113) were patent at late catheterization, but 1 right IMA was diffusely narrowed. One left IMA had acute angulation with 50% stenosis proximal to the distal anastomosis, which was unchanged over the follow-up interval. There were 100 patent saphenous vein bypasses at one year and 87 at late catheterization. Late closure of coronary bypass grafts is secondary to progression of coronary disease, atherosclerosis of the bypass conduit, or intimal proliferation. Because we have not encountered the latter two causes of conduit closure, IMA grafts remain our graft of choice for nonemergent operations in patients under 60 years of age having revascularization of the left anterior descending coronary artery system.

Late sequelae of perioperative myocardial infarction.

The late suquelae of myocardial injury occurring at the time of direct myocardial revascularization are unknown. Fifty of 500 consecutive patients undergoing aortocoronary bypass grafting developed both electrocardiographic and enzymatic evidence of myocardial injury. They were matched with 50 patients of similar age, sex, history of previous infarction, severity of angina, degree of coronary arteriosclerosis, and level of ventricular function as determined by preoperative angiographic studies. The conduct of the operation was identical in each group except for prolongation of total cross-clamp time in those patients with myocardial injury. The total number of vessels grafted, the conduit used, and the operative mean graft flow were similar. Results of treadmill stress testing at 24 to 36 months were not significantly different between groups. Angina status, long-term survival, graft patency, and ventricular function were not adversely affected by intraoperative myocardial injury. However, postoperative ventricular function and stress test performance were related to graft patency.

Severe cyanosis due to atrial septal defect and an anomalous inferior vena caval valve.

Uncomplicated atrial septal defect is often associated with mild arterial desaturation. A case is reported with severe cyanosis and life-threatening hypoxemia due to an atrial septal defect. Cardiac catheterization revealed normal right heart pressures and an atrial septal defect with shunting of inferior vena caval blood into the left atrium. At surgery an anomalous inferior vena caval valve was found directing inferior vena caval blood into the left atrium. The embryologic basis for this association is discussed. The delayed onset of severe cyanosis may have been contributed to by the thoracic scoliosis.

Coronary ostial stenosis.

Symptomatic, nonsyphilitic, acquired coronary ostial stenosis is a rare angiographic finding and was found in 0.13% of 3000 coronary angiograms. Three females with this lesion have been treated surgically. Two had left coronary ostial involvement. Coronary angiography may result in catheter tip occulsion of the ostium with chest pain, dyspnea, diaphoresis, systemic hypotension and abrupt fall in pressure at the catheter tip. Recognition of this entity is necessary for safe coronary angiography. Involvement of the left ostium carries the same serious prognosis as does left main coronary disease.

Sympathetic control of the forearm blood flow in man during brief isometric contractions.

Experiments were performed to assess the possible neurally mediated constriction in active skeletal muscle during isometric hand-grip contractions. Forearm blood flow was measured by venous occlusion plethysmography on 5 volunteers who exerted a series of repeated contractions of 4 s duration every 12 s at 60% of their maximum strength of fatigue. The blood flows increased initially, but then remained constant at 20-24 ml X min(-1) X 100 ml(-1) throughout the exercise even though mean arterial blood pressure reached 21-23 kPa (160-170 mm Hg). When the same exercise was performed after arterial infusion of phentolamine, forearm blood flow increased steadily to near maximal levels of 38.7 +/- 1.4 ml X min(-1) X 100 ml(-1). Venous catecholamines, principally norepinephrine, increased throughout exercise, reaching peak values of 983 +/- 258 pg X ml(-1) at fatigue. Of the vasoactive substances measured, the concentration of K+ and osmolarity in venous plasma also increased initially and reached a steady-state during the exercise but ATP increased steadily throughout the exercise. These data indicate a continually increasing alpha-adrenergic constriction to the vascular beds in active muscles in the human forearm during isometric exercise, that is only partially counteracted by vasoactive metabolites.