An aggressive surgical approach to coronary disease

Advances in the prevention and treatment of cardiovascular disease

Over the past thirty-five years, U.S. age-adjusted mortality from cardiovascular disease declined 50 percent. This marked reduction reflects advances in the prevention, diagnosis, and treatment of common cardiovascular conditions. Pharmaceutical agents play a major role in prevention of atherosclerosis and its consequences: heart attack, stroke, and heart failure. Additionally, novel device-based therapies contribute to the decline in cardiac morbidity and mortality. Whereas innovative strategies based on accurate imaging of the heart and blood vessels are implemented widely now, hope exists that lifestyle changes, early risk-factor screening, and more efficacious drugs will strikingly reduce cardiovascular disease in the future.

Initial experience using an intraluminal shunt during revascularization of the beating heart

BACKGROUND

For decades, surgeons have relied on extracorporeal circulation and induced cardiac asystole to provide a bloodless, motionless field in which to construct coronary bypass grafts. However, the technique of coronary grafting without heart-lung support is now being revitalized. The current resurgence of off-pump coronary artery bypass grafting and the advent of less invasive incisions make it imperative that technical advances be applied to maximize the safety of these procedures.

METHODS

This report describes an inexpensive intraluminal shunt that maintains coronary perfusion, prevents ischemia, reduces backbleeding, and molds the suture line to prevent accidental missuturing of the posterior coronary wall.

RESULTS

In 63 patients, saphenous grafts were placed to the left anterior descending (49), diagonal (9), and right coronary artery (27) without extracorporeal circulation using an intraluminal shunt. There were no deaths (0% mortality) and one perioperative infarction (1.5%). Complication and graft patency rates were comparable with those obtained by conventional techniques.

CONCLUSIONS

Temporary intraluminal shunting greatly facilitates the surgeons' operative environment by permitting safe and precise construction of coronary artery grafts on the beating heart in a bloodless field. Intraluminal shunting may have future implications on the ability to perform safe and reproducible grafting on the beating heart through minimally invasive or endoscopic approaches.

Assessment of coronary bypass surgery and percutaneous transluminal coronary angioplasty

Coronary bypass surgery developed as another in a line of surgical procedures dating back more than 60 years. The medical profession at first assessed this procedure with time-honored anecdotal techniques. Gradually, for a variety of reasons, improved methods of comparisons worked their way into assessments of bypass surgery. Randomized controlled trials met resistance but have been very influential. Assessment of percutaneous transluminal coronary angioplasty has benefited from the knowledge generated during the last 25 years, but clinicians have been slower to apply the most advanced techniques.

Myocardial revascularization by laser: a clinical report

Methods used to revascularize ischemic myocardium have included arterial reconstruction, coronary artery bypass grafting, providing direct circulation from the intraventricular chamber, and techniques to promote collateral circulation. Ventricular channels from the epicardial surface through the endocardium are readily made with the CO2 laser. Animal experiments suggest that these channels protect the ischemic myocardium and provide circulation to the muscle from the ventricular chamber. Clinical use of the CO2 laser in conjunction with aortocoronary bypass grafting is reported in a patient with three-vessel coronary artery disease and total occlusion of the left anterior descending coronary artery (LAD), and hypokinesis of the anterior wall and apex. Following bypass a series of laser channels were made in the hypokinetic area of the left ventricle. Postoperative myocardial Tc PYP scans were within normal limits, including the previously dyskinetic anterior apical area. Serial EKGs remained unchanged from the preoperative status. Creatinine phosphokinase-myocardial band (CPK-MB) was elevated to 6 on the first and second postop day and was 0 from the third day. The patient was not recatheterized. The technique of myocardial revascularization by laser may be a viable addition to present treatment modalities. Further investigation and long-term follow-up are needed.

Accuracy of serial myocardial perfusion scintigraphy with thallium-201 for prediction of graft patency early and late after coronary artery bypass surgery. A controlled prospective study

To assess the accuracy of serial myocardial perfusion scintigraphy with thallium-201 (201Tl) to predict graft patency early and late coronary artery bypass surgery, rest and exercise 201Tl and coronary arteriography were performed preoperatively and 2 weeks and 1 year after operation. The scintigraphic results were compared with graft patency, symptoms, left ventricular function and physical work capacity in a consecutive series of 55 patients with a total of 154 grafts. Serial 201Tl had an 80% sensitivity, 88% specificity and 86% overall accuracy in detecting or excluding graft occlusion, which was predicted by reversible ischemia as well as persistent "new scar" segments. Occluded grafts were correctly localized by 201Tl scintigraphy in 61%. Postoperative apical 201Tl defects were frequent (two-thirds of cases), and were the result of intraoperative transapical venting of the left ventricle. After coronary bypass graft surgery, ejection fraction at rest was unchanged. Left ventricular end-diastolic pressure and physical work capacity improved significantly. In the presence of new perfusion defects detected postoperatively, physical work capacity was reduced significantly. New 201Tl defects in addition to typical or atypical angina provided a high probability of graft occlusion, while in the absence of new 201Tl defects all grafts were patent in more than 90% of patients, all of whom had no or only atypical chest pain. We conclude that serial 201Tl imaging after coronary artery bypass surgery is an accurate noninvasive method that can be used routinely to assess graft function, to localize spatially occluded grafts and to identify patients with a high likelihood of graft occlusion who may need invasive studies.

Transventricular revascularization by laser

Transventricular acupuncture or revascularization by the method of producing channels between the ventricular cavity and the ischemic myocardium has challenged several investigators. The concept of producing these channels using high-energy CO2 laser was based on the finding that the laser beam could produce small channels devoid of debris, and fibrosis would not occur. Four groups of mongrel dogs with six animals in each group were studied. In three groups the left anterior descending (LAD) branch of the coronary arteries was ligated above the first diagonal, and channels were made in the myocardium according to the protocol for each group. The fourth group was the control, the LAD was ligated but the myocardium was not exposed to laser treatment. In the control group all animals died within 20 minutes of LAD ligation. Animals in the other groups survived ligation with laser, and were subsequently sacrificed at varying intervals. At autopsy the epicardial component of the channels was visible. Penetration through the myocardium could be demonstrated. Microscopically the channels were patent and endothelialized. Further investigations are in process, but we believe laser channels protect and nourish the ischemic myocardium.

Thallium-201 myocardial imaging before and after coronary revascularization: assessment of regional myocardial blood flow and graft patency

Twenty patients underwent myocardial imaging with Thallium-201 (201Tl) before and subsequent to coronary artery bypass grafting. All patients had rest and maximal treadmill exercise imaging postoperatively. Eleven of the 20 patients had rest and exercise 201Tl images preoperatively; 9/20 only had rest imaging preoperatively. Postoperative regional exercise perfusion was improved in seven of the 11 patients who had preoperative exercise images, and was associated with regional graft patency in each case. Thirteen of 20 patients showed no new defect with postoperative exercise imaging. The remaining seven patients developed or had an increased defect with exercise. The patients with no new perfusion defects during postoperative study has 26/30 grafts patent (87%). Patients developing a new perfusion defect with exercise had fewer grafts patent (7 of 13 [54%]; P less than 0.03). In these seven cases, a new exercise-induced defect was associated with regional graft closure or residual nonoperated disease. Knowledge of the preoperative coronary anatomy allowed the distinction between ungrafted areas and regional graft dysfunction. We conclude that preoperative and postoperative 201Tl imaging may noninvasively predict graft closure and/or improved regional perfusion with patent grafts.

Treatment of severe coronary artery disease with 5, 6, and 7 saphenous vein bypasses: review of 131 consecutive patients

One hundred thirty-one consecutive patients who received 5, 6, and 7 bypass grafts are analyzed. Ages ranged from 31 to 74 years. The male-to-female ratio was 7:1. As an indication of severity of disease, 25% were classified as having impending myocardial infarction and 46.6% were classified in New York Heart Association Functional Class IV. Left ventricular function was impaired in 37.4%, and 30% of the patients had left main coronary obstruction. Nonfatal perioperative myocardial infarction occurred in 4.6%. The hospital mortality was 3%. One hundred percent follow-up (5 to 55 months) revealed 4 late deaths, 3 presumably of cardiac origin. Only 7 patients in the postoperative follow-up group have complained of angina; 1 has since undergone successful reoperation.

Improved survival after coronary bypass surgery in patients with poor left ventricular function: role of intraaortic balloon counterpulsation

The operative mortality rate of aortocoronary bypass surgery in 23 patients with poor left ventricular function (ejection fraction 0.30 or less) operated on in 1973-74 was 34.7 percent. The incidence rate of operative myocardial infarction was 30.4 percent. In an attempt to improve survival, intraaortic balloon counterpulsation was used therafter in 25 similar patients. Counterpulsation was instituted preoperatively and continued intra- and postoperatively for 2 to 5 days. Preoperative studies revealed an "unloading" effect of the left ventricle, with significant reductions of systolic arterial blood pressure, end-diastolic pulmonary arterial pressure and end-diastolic left ventricular volume and pressure. Metabolic improvement was demonstrated by the lesser production of myocardial lactate after pacing-induced tachycardia when the ventricle was balloon-assisted. Intraoperatively, blood flow through the vein graft was found to increase with counterpulsation. The rate of operative myocardial infarction was reduced to 4 percent and the mortality rate to 8 percent. In patients who have sustained a significant loss of functioning myocardium, the beneficial hemodynamic and metabolic effects of intraaortic balloon counterpulsation appear to prevent furhter, possibly critical, myocardial damage in the perioperative period.

Effects of amyl nitrite on phasic aortocoronary bypass graft blood velocity in man

With the use of a Doppler flowmeter catheter, phasic instantaneous aortocoronary saphenous vein bypass graft blood velocity was continuously measured during the inhalation of amyl nitrite in 20 closed-chest conscious subjects. Administration of amyl nitrite augmented peak diastolic and systolic graft blood velocity within 10 seconds and maximal blood velocities were recorded between 8 and 60 seconds after inhalation. Control mean (+/- 1 S.D.) bypass graft blood velocity was 25 +/- 10 cm. per second and after amyl nitrite 46 +/- 14 cm. per second, resulting in an average 84 per cent rise of blood velocity. It is concluded that amyl nitrite increases aortocoronary bypass graft blood velocity, suggesting a possible enhancement of blood flow to the distal native circulation in patients so operated upon.

External counterpulsation: coronary hemodynamics and use in treatment of patients with stable angina pectoris

External pressure counterpulsation (ECP) has been reported to improve the clinical status of patients with angina pectoris. To document the mechanisms for such an improvement left ventricular oxygen consumption and lactate metabolism, coronary sinus blood flow, and cardiac index were studied in 10 patients with angina pectoris 1) prior to and during ECP; and 2) during right atrial pacing before and after 4 consecutive 2-hour sessions of ECP treatment. During ECP peak early and mean arterial diastolic pressures were significantly raised above control values by 32 and 13% respectively. However, coronary sinus blood flow, left ventricular oxygen consumption and left ventricular lactate extraction, mean systolic arterial pressure and cardiac index were not significantly altered by ECP. Right atrial pacing at 140 beats/min increased coronary sinus blood flow 70% over control values and induced angina and ischemic ST segment changes in 8 patients before and after 4 consecutive treatments of ECP. ECP treatment did not significantly modify the above metabolic and hemodynamic responses at rest or during atrial pacing. Although 5 patients reported improvement in angina symptoms the effect was transitory. No significant improvement over pre ECP-treatment exercise angina threshold was observed immediately following or at 1 and 3 months post treatment. This method of noninvasive circulatory assistance appears to be of doubtful value in the management of patients with stable angina pectoris.

Reappraisal of the role of the diabetic state in coronary artery disease

Clinical and coronary arteriographic findings were evaluated in patients with angina pectoris who were considered not to have diabetes mellitus or to have chemical or clinical diabetes. Each of the three groups consisted of 100 consecutive referred patients. Neither the age of the patients nor duration of symptoms differed significantly among the groups. Hypertension, gout, and peripheral vascular disease were more frequent in the patients with clinical diabetes. There was no difference in serum cholesterol concentration among the groups, but plasma triglyceride levels and the frequency of type 4 hyperlipoproteinemia were significantly higher (p less than 0.01) in the chemical and clinical diabetic groups than in the nondiabetic patients. Coronary arteriographic observations indicated that the severity of the coronary arterial disease was greater in both diabetic groups than in nondiabetic patients. The difference in the coronary scores among the three groups of patients interacts to some extent with the triglyceride level, since a high score in the diabetic groups was noted only in the presence of an elevated tryglyceride concentration. The results indicate that the increased severity of coronary arterial disease in diabetic patients is not attributable to age, duration of symptoms, hypertension, type -4 hyperlipoproteinemia, or apparent severity of the glucose intolerance.

Aortocoronary graft flow and reactive hyperaemia in relation to postoperative myocardial infarction

Blood flow through aortocoronary venous grafts and its response to a brief period of arterial occlusion--reactive hyperaemia--were studied in relation to the development of postoperative myocardial infarction. In 40 patients with intractable angina due to obstructive coronary artery disease, 72 aortocoronary venous grafts were constructed. In 18% of the grafts there was no response to the flow to temporary occlusion, due to absence of reactive hyperaemia. In the remaining grafts the flow increased from 17% to 26%. In 17-5% of the patients postoperative myocardial infarction was diagnosed. No relation could be established between this control flow through aortocoronary grafts and postoperative myocardial infarction. A significant difference was found in the magnitude of the reactive hyperaemia following occlusion of the graft between patients who developed myocardial infarction (13-0%) and those who did not (26-8%). Some of our observations suggest that the myocardium is in a state of reactive hyperaemia after coronary surgery. With certain technical precautions the flow changes caused by reactive hyperaemia can be used as an indicator of the result to be expected from bypass surgery.

Treatment of severe coronary artery disease with quadruple and quintuple saphenous vein grafts. Review of 100 consecutive patients

In order to establish the anatomic criteria, the functional results, and the safety of complete myocardial revascularization for severe coronary artery disease, 100 consecutive patients who received four or five saphenous-vein grafts were analyzed. Ages ranged from 37 to 75 years (mean, 56 years). Men predominated by a ratio of 12:1. As an indication of the severity of multiple-vessel disease, 28 percent were in functional class 4, and left ventricular function was classified as good in 47 percent, as fair in 44 percent, and as poor in 8 percent. Coronary arterial scores ranged from 9 to 15 (average, 12.2). Fourteen patients had significant left main coronary arterial obstruction. All 100 patients had grafts to the left anterior descending coronary artery; 96 to the right coronary artery; 94 to the obtuse marginal branch of the circumflex; 78 to a diagonal branch of the left anterior descending; and 27 to the distal circumflex. Operative mortality was 5 percent. Nonfatal perioperative myocardial infarction occurred in 10 percent, and only one of these had low cardiac output. Follow-up from 5 to 23 months showed 95 percent of the patients to be improved, with 70 percent free of angina. Two late deaths occurred, for an overall mortality of 7 percent.

Left ventricular aneurysm. Preoperative hemodynamics, chamber volume, and results of aneurysmectomy

Angiocardiographic characteristics of the residual contracting left ventricle (LV) have been examined in 16 patients with anterolateral ventricular aneurysms (VA). In each patient a contractile section (CS) of the LV was clearly demarcated from the remaining aneurysmal section (AS). Using a double hemispheroid model, volumes of CS and AS were separately estimated by a modified area-length method. The volume of CS plus AS agreed closely with the volume of total LV estimated by the conventional area-length method. End-diastolic volume (EDV) of total LV ranged from 79 to 312ml/72. Aneurysmal section volume ranged from 8 to 264 ml/m2. End-diastolic volume of the contractile section ranged from 52 to 159 ml/m2 (mean, 100+/-8 (se); normal, 78+/-6). Contractile section ejection fraction (EF) showed a wide range, from 15% to 79% (mean 40%+/-17% SD). Nine patients underwent resection of VA. Three of six operated patients with CS EF less than 44% died; no survivor in this group has improved by more than one functional class (New York Heart Association classification). Three operated patients had CS EF greater than 45%; all survived and are improved, two having moved from class IV to class I. These data suggest that the EF of the contracting residual LV may be an important predictor of the outcome of resection of VA.

Dissection and rupture of the ascending aorta. Unusual complications of aortocoronary bypass surgery

This is a report concerning two cases of unusual complications, dissection and rupture of the ascending aorta, secondary to saphenous vein bypass surgery. We recommend that evaluation of patients undergoing saphenous vein bypass surgery include careful image-intensifier fluoroscopic examination during coronary arteriography. If aneurysmal dilatation of the aorta or calcification is observed, ascending aortography should be performed to better evaluate the aorta, and surgeons should be alerted to use appropriate maneuvers and techniques to minimize the risk of complications in the aortic site of the vein anastomosis. Internal mammary coronary-artery bypass should be the procedure of choice in such conditions.

Preoperative coronary angiographic prediction of bypass flow and short-term patency

A quantitative preoperative coronary angiographic index was defined in 148 patients undergoing coronary revascularization. Each diseased vessel was scored 0-3, for both diameter and quality of run-off. The sum of the scores for diameter and run-off constituted the numerical index for the diseased vessel. Correlations between the index and graft flow measured by electromagnetic flow meter at surgery were established in 259 bypassed vessels. The highest scores (5-6) were associated with higher flows, and the lower scores (0-4) with the lower flows (P less than 0.005). Repeat angiography performed 2 wk postoperatively in 110 patients demonstrated 174 graft patencies and 15 graft closures. Mean flow in open grafts was 82 +/- 41 ml/mn vs. 60 +/- 23ml/mn in closed grafts (P less than 0.005). It is concluded that graft flow is predictable from preoperative Coronary Angiographic Index and that higher flow and index scores are more likely to be associated with graft patency than low flows and index scores.

Rest and exercise potassium-43 myocardial perfusion imaging for the noninvasive evaluation of aortocoronary bypass surgery

Sixteen patients undergoing aortocoronary bypass surgery were evaluated with rest and exercise potassium-43 ( 43 K) myocardial imaging and contrast angiography an average of 5.5 months postoperatively. The results of 43 K imaging allowed the division of these patients into two groups. Group 1 consisted of patients in whom there was either normalization or significant improvement in postoperative images when compared to abnormal preoperative studies (five patients), or patients in whom preoperative imaging was not accomplished but whose postoperative images both at rest and exercise showed a normal homogenous pattern of 43 K distribution (four patients). All patients in this group had at least one patent bypass graft, and 13 of 16 total grafts were patent. Group 2 consisted of seven patients in whom postoperative rest and exercise 43 K studies were either not significantly different from preoperative evaluation, or had worsened. Of these patients, three experienced intraoperative infarction, two demonstrated significant distal native coronary disease, and one had a single occluded graft. In both groups there was good correlation between the anatomic sites of graft patency or occlusion and the location of either increased perfusion or lack thereof on the 43 K image. Perfusion abnormalities occurring in the presence of occluded grafts, or improvement in perfusion occurring in the presence of patent grafts were best appreciated by comparison of exercise images. Abnormalities occurring in the presence of infarction were detected at rest as well. Thus, in this initial group of patients, 43 K rest and exercise myocardial imaging appeared to offer a sensitive noninvasive means of evaluating the results of aortocoronary bypass surgery.

Left main coronary artery stenosis; results of coronary bypass surgery

Fifty-six patients with severe stenosis of the left main coronary artery underwent coronary bypass surgery between January 1970 and December 1971. All patients had angina pectoris. Seventy-five per cent of the patients had an unstable anginal pattern. There were six perioperative deaths for a surgical mortality of 10.7%. Of the 50 patients surviving surgery, 96% are alive from 12 to 36 months postoperatively, 90% have had a significant reduction in anginal symptoms and 76% are asymptomatic. Postoperative catheterization studies, performed one to 28 months after surgery in 31 patients, showed that 83% of 75 bypass grafts were widely patent. In each patient studied there was at least one widely patent graft to the left coronary artery. Six patients had exercise studies using supine bicycle ergometry during pre- and postoperative cardiac catheterization. These studies demonstrated improvement in exercise tolerance and in left ventricular hemodynamics after coronary surgery.

A new surgical approach to myocardial revascularization--internal mammary artery to coronary vein anastomosis

Sallam, I. A., and Kolff, W. J. (1973).Thorax, 28, 613-616. A new surgical approach to myocardial revascularization—internal mammary artery to coronary vein anastomosis. Myocardial ischaemia was established in anaesthetized animals (five dogs and five sheep) by ligating the anterior descending interventricular branch of the left coronary artery. Once the ischaemic changes became evident electrocardiographically, retrograde perfusion of the coronary vein draining the ischaemic area was established by connecting the internal mammary artery to the coronary vein. The vein was ligated proximally.

When retrograde perfusion of the coronary vein was begun, the signs of ischaemia gradually disappeared but could be reproduced by clamping the internal mammary artery. This indicated the effectiveness of the anastomosis in establishing an efficient new blood supply to the ischaemic area.

The present approach offers a new prospect to patients in whom the coronary artery is not suitable for coronary vein bypass grafting due to extensive diffuse narrowing. Further application may be found in patients with cardiogenic shock after myocardial infarction. Direct immediate revascularization by this approach may prove of value in such cases.

Preinfarctional (unstable) angina--a prospective study--ten year follow-up. Prognostic significance of electrocardiographic changes

One hundred and forty patients with preinfarctional (unstable) angina were followed for ten years for the purpose of determining the natural history and the prognostic significance of electrocardiographic findings. The cumulative survival rate for the 140 patients was as follows: 12 months: 82%; 24 months: 75%; 36 months: 69%; 60 months: 61%; and 120 months: 48%. Twentyone percent (29 of 140) of the patients developed an acute myocardial infarction within eight months of the onset of the diagnosis of preinfarctional angina with an associated mortality of 41.4% (12 of 29). A combination of high-risk factors in a patient, e.g., frequent angina in the hospital, prior stable angina, and ischemic ST change during pain, identified his as a high-risk case. The high-risk subgroup (54) had a cumulative survival rate as follows: 12 months: 57%; 24 months: 47%; 36 months: 37%; 60 months: 27%; and 120 months: 19%. Thirty-five percent (19 of 54 patients) of this subgroup developed a myocardial infarction within three months of the onset of preinfarctional angina with an associated mortality rate of 63% (12 of 19 patients). At the first year follow-up, 18% (25 of 140) of the patients died; 74% (104 of 140) had less angina; and 8% (11 of 140) did not show a change in their anginal pattern. These data can be used as a basis for a controlled trial of surgical treatment for preinfarctional angina.