Myocardial Revascularization In Patients Research Articles

Coronary artery spasm immediately following extubation of the trachea.

It is now generally accepted that coronary artery spasm plays an important role in the genesis of myocardial ischemia'<. Perioperative coronary artery spasm appears to be observed most frequently after myocardial revascularization in patients undergoing coronary artery bypass surgery3,4,5. In this report, we present a case of coronary artery spasm in noncardiac surgery, which occurred just after extubation of the trachea.

Coronary ostial reconstruction: Technical issues

Coronary ostial reconstruction may be the preferred alternative to reestablish antegrade myocardial revascularization in patients with isolated ostial stenosis. The technical steps of reconstruction are described. The ultrasonic aspirator is a helpful implement in the dissection of the left main and the proximal right coronary arteries. Satisfactory results of coronary ostial reconstruction in the current era seem to fulfill its promise.

Prevention of Neurological Injury during Myocardial Revascularization in Patients with Calcific Degenerative Aortic Disease

Neurological injury following myocardial revascularization may result from embolization of atheromatous debris from the diseased ascending thoracic aorta. Eight patients with calcified aortas who underwent elective myocardial revascularization suffered major strokes as a result of manipulation and clamping of the diseased ascending aorta during a 30-month period before July, 1981. Computerized axial tomography scans demonstrated multiple cerebral infarctions in each patient. Six patients never regained consciousness and died as a result of neurological injury; 2 patients regained consciousness but were left with major neurological deficits. Later, 21 patients with calcific aortic degenerative disease underwent a specific operative protocol, designed to prevent neurological injury during elective myocardial revascularization. All 21 patients recovered without neurological complications. Specific attention to operative technique allowed this difficult group of patients with incapacitating angina and calcific degenerative aortic disease to have the benefit of coronary bypass.

７０歳以上の高齢者における内胸動脈（ＩＭＡ）を用いた多枝冠動脈バイパス術の検討

７０歳以上の高齢者における内胸動脈（ＩＭＡ）を用いた多枝冠動脈バイパス術の検討

Effects of myocardial revascularisation in patients with effort angina and those with effort and nocturnal angina.

The effects of coronary artery bypass graft operation were studied in 32 patients with daytime ambulatory ST segment changes and 14 patients with daytime and nocturnal angina and ST segment changes. Patients had ambulatory ST segment monitoring and exercise testing before and after operation and coronary arteriography was repeated in 34 patients after operation. Before operation, patients with daytime and nocturnal ischaemia tended to have more severe coronary artery disease, lower exercise tolerance, and more frequent ambulatory ST segment changes than those who had daytime ST segment changes only. After operation chest pain recurred in 22% of patients and ST segment depression during exercise testing or ambulatory ST segment monitoring recurred in 37% of the patients and was significantly more frequent in those with nocturnal ischaemia than in those with daytime ischaemia. Graft patency rates were similar in patients with and those without recurrence of ischaemia. After operation the frequency and magnitude of ST segment changes and exercise duration were improved in patients with preoperative daytime angina and also in those with daytime and nocturnal angina. The improvement was more pronounced in the latter groups. Thus, absence of postoperative angina is not a reliable indicator of the absence of reversible myocardial ischaemia. After revascularisation, patients with rest and nocturnal angina can expect relief from ischaemia, and if this recurs postoperatively, the threshold is improved and pain usually occurs only on exertion.

Effect of venous retroperfusion on experimental myocardial ischemia in the open-chest pig

Venous retroperfusion, by arterialization of the coronary sinus or the vein accompanying an ischemic artery, has been suggested as an alternative method of myocardial revascularization in patients with severe coronary disease in whom direct revascularization would be an unacceptable risk or technically impossible. This study was carried out to assess whether or not venous retroperfusion can increase myocardial blood flow in the area of ischemia after sudden occlusion of a normal coronary artery in an animal, the pig, with a coronary vasculature similar to that of humans. It was found that net flow measured with an electromagnetic flowmeter through either an aorta-to-coronary sinus shunt or an aorta-to-left anterior descending coronary vein shunt after occlusion of the left anterior descending artery was at first high but rapidly decreased toward zero flow within 1 hr. Blood flow in the ischemic region measured by the microsphere method 20 min after coronary occlusion did not increase. This disparity between electromagnetic flow and regional flow suggests that there are venous-to-thebesian or venous-to-venous shunts into the systemic and pulmonary circulation through vessels >14 μm. It is unlikely that effective oxygen or metabolite exchange would occur in vessels this size.

Electrophysiologic studies before and after myocardial revascularization in patients with life-threatening ventricular arrhythmias

Electrophysiologic studies with programmed cardiac stimulation were performed in a selected group of 17 patients with severe proximal coronary artery disease involving at least 2 major vessels and left ventricular ejection fractions greater than 30% who were undergoing coronary artery bypass graft surgery after prehospital cardiac arrest or ventricular tachycardia (VT) unassociated with acute myocardial infarction. Before surgery and without antiarrhythmic drug therapy, programmed cardiac stimulation induced ventricular fibrillation (VF) in 4 patients, and VT (greater than or equal to 5 beats) in 11 patients. Inducible VT or VF was suppressed by antiarrhythmic drugs in 7 of 13 patients in whom they were tried. Patients underwent coronary artery bypass graft surgery unassociated with perioperative myocardial infarction. When studied again an average of 19 days after surgery, 10 patients had no inducible VT or VF without antiarrhythmic drug therapy; 6 had induced VT. One patient had spontaneous VT. An effective antiarrhythmic regimen that suppressed inducible or spontaneous VT, or both, was defined by serial electrophysiologic studies in 4 patients, whereas 3 patients continued to manifest electrically inducible VT with all antiarrhythmic regimens tested. All but 1 patient, in whom postoperative VT could not be suppressed, are free of arrhythmias after a mean follow-up period of 23 months (range 6 to 53). It is concluded that myocardial revascularization alone may improve the abnormal electrophysiologic findings in certain patients; however, this effect of coronary artery bypass graft surgery is unpredictable, and pre- and postoperative electrophysiologic studies are recommended as part of the evaluation of these patients.

Improved long-term survival following myocardial revascularization in patients with severe left ventricular dysfunction

The natural history of patients with coronary artery disease associated with poor left ventricular (LV) function is dismal. This report analyzes the efficacy of myocardial revascularization in this subset of patients with coronary artery disease manifesting severe LV dysfunction on the basis of LV angiography, LV ejection fraction (LVEF), and left ventricular end-diastolic pressure (LVEDP). For the 2 1/2 year period ending November, 1977, 59 consecutive patients with coronary artery disease complicated by severe LV dysfunction underwent aorta-coronary bypass at the University of Western Ontario. All patients had angina refractory to medical therapy. Objective criteria for compromised LV function included the presence of three or more dysfunctional (hypokinetic of akinetic) segments on biplane LV angiography. Eighty-three percent (49/59) of patients had triple-vessel coronary artery disease. The mean LVEF for the series was 0.28 and the mean LVEDP was 18 mm Hg. The duration of follow-up was 24 to 60 months (mean 37 months), with follow-up survival data available on 100% of patients. The hospital mortality was 1.7% (1/59), and there were nine late deaths. The 5 year actuarial survival rate (+/- SEM) was 80% +/- 6%. Of the 44 long-term survivors available for direct assessment, 98% (43/44) report improvement with respect to angina and 66% (29/44) are totally asymptomatic. Eighty percent (28/35) of the long-term survivors under the age of 65 years are currently employed. These results indicate that myocardial revascularization can be performed in patients with severe ischemic LV dysfunction at very low risk and, further, that operation results in a dramatic improvement in survival expectations compared with optimal medical therapy.

Aortic valve replacement without myocardial revascularization in patients with combined aortic valvular and coronary artery disease.

To test the hypothesis that coronary artery bypass grafting (CABG) is not routinely required in patients undergoing aortic valve replacement (AVR) who have coexistent coronary artery disease (CAD), we compared the results of operation in 55 consecutive symptomatic patients who had CAD and underwent AVR without CABG with results in another 142 patients without CAD who underwent AVR during the same period, and with published results from other centers in which CABG was used in patients with CAD who underwent AVR. Operative mortality was 4% in patients with CAD and 5% in patients without CAD. Late survival was not significantly different between the two groups when analyzed for the entire population (80% survival at 3 years in CAD patients, 82% for non-CAD patients), or for the subgroup of patients with aortic stenosis, aortic regurgitation or aortic stenosis plus regurgitation. Eight patients with CAD (15%) developed recurrent angina after AVR (mean follow-up 43 months); only three patients (6%) required CABG because of medically refractory angina (12-43 months). Operative mortality, operative infarction (9%), recurrent angina and long-term survival in patients with CAD after AVR were similar to those at other centers after AVR plus CABG. These data suggest that preoperative detection of CAD does not necessitate CABG in all patients at the time of AVR.

Myocardial revascularization in patients with chronic renal failure

Symptomatic coronary artery disease in patients with chronic renal failure can complicate their management in a dialysis program. Hypotension associated with hemodialysis and the anemia of chronic renal disease can produce anginal episodes refractory to medical management. Untreated coronary artery disease may be a contraindication to renal transplantation in an otherwise acceptable candidate. We have encountered three cases of coronary artery disease severe enough to necessitate coronary bypass in patients from our long-term hemodialysis program. All three patients had uncomplicated postoperative courses, none had perioperative infarction, and in all three patients postoperative angiography demonstrated patency of all grafts. One patient subsequently underwent successful renal transplantation; the other two patients have continued in hemodialyses since bypass. We believe our experience and the reported experience of others confirm the feasibility of coronary bypass grafting in patients with chronic renal failure.

Myocardial Revascularization in Patients Receiving Long-Term Propranolol Therapy

Twenty-seven patients receiving long-term propranolol therapy underwent myocardial revascularization to relieve stable or unstable angina. The patients were randomly divided into two groups, one (Group 1) in which propranolol was discontinued 48 hours prior to operation and one (Group 2) in which patients received a final dose of propranolol 1 to 2 hours prior to operation. Several physiological variables were compared, and there was no statistically significant difference between the groups except for a slower pulse rate in Group 2 patients. Although the patients in Group 1 showed a greater frequency of hypertension before bypass, the incidence of postoperative complications and perioperative myocardial infarction was the same for both groups. The findings of this study indicate that myocardial revascularization is safe even if propranolol is administered up to 1 or 2 hours before operation.

Sympathetic Denervation in Association with Coronary Artery Grafting in Patients with Prinzmetal's Angina

Myocardial revascularization in patients with Prinzmetal's angina has yielded variable results. Two patients are presented who underwent partial cardiac sympathectomy in combination with coronary artery grafting for typical variant angina associated with severe organic obstructive coronary artery disease. Late results 12 and 18 months postoperatively have been excellent in both instances as shown by clinical and angiographic evaluation.

Coronary Artery Surgery: Operative Technique and Patient Education

Coronary artery surgery, the preferred technique for myocardial revascularization in patients with ischemic heart disease, promptly increases blood flow to areas of the myocardium distal to the coronary obstruction. CAS completely relieves angina in 90% of patients. The risk of 1 to 5% is decreasing as operative technique and patient selection improve. Patients having CAS need comprehensive preoperative and discharge teaching to restore them to normal, active, optimistic lives.

Myocardial revascularization in patients with poor ventricular function

Eighty patients with evidence of impaired ventricular function by ventriculography were reviewed. On the basis of the ejection fraction, these patients were divided into three groups. Those with ejection fractions less than 0.2 were considered in very poor condition, those with ejection fractions of 0.2 to 0.4 were considered in poor condition, and those with ejection fractions with between 0.4 and 0.6 were considered fair. Suitability of vessels for bypassing and the presence or absence of collateral cirulation on the cinearteriograms was also noted for possible influence on result. Operative mortality rate in patients having complete repair, defined as bypassing all major vessels with significant obstruction, was 7 per cent. In 26 patients having incomplete repair, the operative mortality was 30 per cent. However, the late mortality rate was not favorably influenced by complete repair, 75 per cent are in improved or good clinical condition, as compared with 65 per cent in the incomplete repair group. As patients with impairment of ventricular contractility are at high risk, it is believed that they should continue to be evaluated on an individual basis for bypass surgery and not categorically denied treatment.

Coronary artery bypass.

Aortocoronary saphenous vein bypass (CAB) has become the preferred technique for myocardial revascularization in patients with ischemic heart disease (1–4). Evaluation of the results of CAB is essential for comparison with the accumulated knowledge of the natural course of coronary heart disease and for improvement of patient selection.KeywordsCoronary Artery BypassEarly MortalityAcute InfarctionPostoperative Myocardial InfarctionSaphenous Vein BypassThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.