James A. Alexander

Left main coronary artery stenosis: Clinical spectrum, pathophysiology, and management

Abstract Atherosclerosis is the major cause of LMCAS. Isolated LMCAS occurs only rarely. Marked narrowing of the LMCA is usually indicative of severe, diffuse coronary atherosclerosis. Physiologically significant LMCAS is present in less than 15% of patients with symptomatic ischemic heart disease. Angina pectoris is the most common symptom in patients with LMCAS. The incidence of unstable angina is higher in these patients when compared to patients without LMCAS. Stress testing may help identify patients with LMCAS if the following criteria are met: (1) greater than 2 mm ST segment depression. (2) prolonged duration of ST segment change after exercise, (3) blunted or decreased heart rate response to exercise, and (4) ST segment change suggesting ischemia at a low heart rate. Coronary angiography provides definitive anatomic description of the location, length, and severity of LMCAS. The procedure can be performed at low risk if proper precautions are taken. Experimentally, 85% reduction in diameter of the LMCA is required to reduce resting coronary blood flow. Parameters of LV function begin to deteriorate at this level and progress as the degree of narrowing increases. General principles of good medical therapy for patients with ischemic heart disease also apply to patients with LMCAS. However, it is important to exercise caution when using agents that lower blood pressure. Patients with LMCAS who are in an unstable state should be hospitalized, monitored, and treated vigorously with pharmacologic agents. If pain persists, intraaortic balloon counterpulsation can be tried as a temporizing measure. Prognosis of medically treated patients with LMCAS is influenced adversely by poor ventricular function, coexistent disease of the right coronary artery, and severity of the narrowing in the left main coronary artery. When surgery is being considered, intraaortic balloon counterpulsation can be useful adjunct in patients with continuing chest pain. However, in the usual patient with LMCAS who is responsive to pharmacologic agents, intraaortic balloon counterpulsation is not necessary. Survival of patients with LMCAS treated surgically is better than that of comparable medically treated patients. However, there are subsets of high- and low-risk patients related to ventricular function, degree of narrowing of the LMCA, and associated disease of other coronary vessels. We conclude that current aggressive medical therapy has eliminated the need for emergency or urgent coronary artery surgery in all but a few patients with LMCAS and persistent symptoms. However, despite the initial success of medical management, the long-term prognosis in these patients is poor. At the present time, surgery should be considered in all symptomatic patients with ≥50% LMCAS.

Mortality, Morbidity, and Cost-Accounting Related to Coronary Artery Bypass Graft Surgery in the Elderly

The purpose of this study was to document early mortality, perioperative complication rate, duration of hospitalization, and costs related to coronary artery bypass graft (CABG) surgery in the elderly. Arbitrarily, elderly patients were defined by age greater than or equal to 65 years; younger patients were less than or equal to 60 years old. A detailed list of specific perioperative complications was analyzed. Early (30-day) mortality was similar between groups, while 120-day mortality was higher among elderly compared with younger patients (7.6% versus 1.3%; p = 0.05). The number of elderly patients with 1 or more complications was also higher than among the younger patients (62% versus 43%; p = 0.05). When the incidences of atrial arrhythmias and transient psychoses were considered minor complications and excluded from consideration, the incidence of major complications was higher in the elderly: 41 major events among 76 younger surviving patients compared with 89 major complications in 61 older surviving patients (p = 0.001). Time spent in the intensive care unit and the duration of postoperative hospitalization were also greater in the elderly (p = 0.01 and p = 0.001, respectively). Finally, the elderly group incurred greater costs than the younger patients (p = 0.03). The likelihood of increased perioperative morbidity in elderly patients is documented in this study. Also, it appears that the increased frequency of complications in elderly patients is associated with a longer hospital stay and greater financial expense. Consequently, the careful preoperative evaluation of these patients, including cautious patient selection, assumes greater importance. After CABG procedures, the highly symptomatic elderly patient may experience dramatic relief of symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Somatosensory Evoked Potential Monitoring of Spinal Cord Ischemia during Aortic Operations

Somatosensory evoked potentials were monitored in 22 consecutive patients undergoing surgical correction of an aortic coarctation. Induction of spinal cord ischemia by cross clamping of the aorta elicited a change in the evoked potential in 9 patients (41%). These alterations occurred within 5 minutes of aortic clamping in 3 cases and after 18 to 21 minutes in the remaining 6 cases. Loss of the somatosensory evoked potential for more than 14 minutes was associated with postoperative neurological deficit. Alteration of the evoked potential within 5 minutes of aortic cross clamping was significantly related to poor collateral circulation shown on the preoperative aortogram. The pathophysiology of evoked potential changes in spinal ischemia is discussed in detail.

Partial deficiency of coagulation factor XI as a newly recognized feature of Noonan syndrome

Four patients with stigmata and cardiovascular abnormalities of Noonan syndrome were found tohave prolonged partial thromboplastin times. Coagulation evaluation disclosed that each had partial deficiency of blood coagulation factor XI (range 25 to 45% of normal; mean 35%). Factor XI deficiency has not been recognized as one of the stigmata of Noonan syndrome. Because of the hemostatic stress of cardiothoracic surgery, factor XI deficiency should be sought in patients with Noonan syndrome.

Acute Neuropsychological Functioning Following Cardiosurgical Interventions Associated With the Production of Intraoperative Cerebral Microemboli

Coronary artery bypass graft (CABG) and valve replacement (VR) surgical patients underwent neuropsychological assessment 1–2 days prior to surgery; 7–10 days postsurgery; and 1 month following hospital discharge. A group of matched healthy controls was tested at identical intervals. Cerebral microemboli in both middle cerebral arteries were quantified during surgery using Doppler sonography. Neuropsychological testing results revealed that the CABG and VR groups did not differ from one another at any assessment point. However, surgical patients performed more poorly than healthy controls across all assessments. Surgical patients, as a group, demonstrated a mild decline in attentional functioning and learning efficiency at the 7–10 day follow-up, but these difficulties essentially returned to baseline by the 1-month follow-up. Intraoperative microemboli counts were not significantly associated with postsurgical neuropsychological functioning in either the CABG or VR group.

Emergency Coronary Artery Bypass Graft Surgery for Threatened Acute Myocardial Infarction Related to Coronary Artery Catheterization

In 20 patients undergoing cardiac catheterization, usually involving balloon-catheter dilation or streptokinase infusion, catheter-induced coronary artery intimal damage resulted in severe chest pain, electrocardiographic evidence of obstruction or dissection of a major coronary artery. These patients were surgically revascularized within 8 hours after the onset of the acute chest pain syndrome. Our experience with pharmacological and catheter-related manipulations to improve coronary blood flow after the ischemic episode but before operation suggested that the additional time spent in the catheterization laboratory was worthwhile. The injured coronary artery was the left anterior descending in 10 patients, the right in 8, the left main in 1 patient, and an obtuse marginal branch of the circumflex in 1. The average number of grafts per patient was 2.5; only 6 patients had single bypass grafts. In 5 patients, intraaortic balloon pumping was used either preoperatively or postoperatively. Inotropic support was used postoperatively in 5 patients, and 7 patients received lidocaine for ventricular irritability. Abnormal elevation of the serum isoenzyme of creatine kinase (CK-MB) was seen in 8 patients, and new Q waves were noted in 4 patients; 3 of these 4 patients with new Q waves also had abnormal serum CK-MB levels. Global ejection fraction obtained by the equilibrium-gated blood pool scan postoperatively was 60 +/- 3%, which was similar to the 62 +/- 3% obtained from the contrast-determined ventriculogram done preoperatively prior to the catheter-related injury. There were no early or late deaths, but morbidity was much higher in the group who had emergency coronary artery bypass grafting (CABG) compared with those who had elective CABG.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term follow-up of transvenous cardiac pacing in children

Abstract Aggressive diagnosis and treatment, both medical and surgical, for congenital or acquired heart disease in children have resulted in an increased need for permanent cardiac pacing systems. However, frequent premature pacemaker revisions have been necessary for many reasons, including lead fractures, noncapture due to increasing threshold, and wound infection or skin breakdown over the pacemaker generator. 1–3 Most pacemaker systems in children have used epicardial leads because of concern for lead dislodgement or damage to intracardiac structures, large lead size relative to small venous access, and difficulty in implanting relatively large pacemaker generators in a suitable prepectoral location. Recent changes in design of pacemaker generators and leads have made use of transvenous systems more tenable even in younger children who require permanent cardiac pacing. 4 However, little information has been reported regarding long-term results of transvenous pacemakers in children.

Relative Efficacy of Left Ventricular Venting and Venous Drainage Techniques Commonly Used during Coronary Artery Bypass Graft Surgery

Sixty patients with symptomatic coronary artery disease undergoing coronary artery bypass graft operation were prospectively randomized into one of six equal groups based on the intraoperative method of left ventricular venting and venous drainage. Group 1 had bicaval venous drainage without snaring and left ventricular venting through the superior pulmonary vein; Group 2, two-stage venous drainage and venting as in Group 1; Group 3, bicaval venous drainage without snaring and no left ventricular vent; Group 4, two-stage venous drainage and no left ventricular vent; Group 5, bicaval venous drainage without snaring and with ascending aortic venting through a catheter; and Group 6, two-stage venous drainage and venting as in Group 5. Left ventricular performance was determined by radionuclide ventriculography from which global ejection fraction and regional wall motion were determined. Cardiac output was obtained by the thermodilution technique. Myocardial temperature was assessed by a needle thermistor during aortic cross-clamping. Serial electrocardiograms and levels of myocardial-specific isoenzymes (serum CPK-MB) were also analyzed. Each of the techniques tested was equally effective as determined by an analysis of intraoperative myocardial cooling and postoperative hemodynamic profiles, radionuclide ventriculography, and ECG or enzymatic evidence of myocardial damage. However, we maintain that this conclusion is valid only if adequate ventricular decompression is provided intraoperatively.

Coronary Artery Bypass Graft Surgery: Clinical Comparison of Cold Blood Potassium Cardioplegia, Warm Cardioplegic Induction, and Secondary Cardioplegia

An analysis of myocardial protection was performed in 45 low-risk patients undergoing coronary bypass procedures who were divided into three equal groups with similar preoperative ejection fractions and coronary artery obstructions. Group 1 (N = 15) received cold blood cardioplegia, Group 2 received cold blood cardioplegia and secondary cardioplegia, and Group 3 received cold blood cardioplegia plus warm cardioplegic induction. The aortic cross-clamp time and the number of bypass grafts were similar among the groups. The following variables were measured serially: electrocardiographic changes, serum myocardial-specific isoenzyme of creatine kinase, cardiac output, left ventricular filling pressure, ejection fraction, and left ventricular wall motion. The three methods evaluated were all effective in protecting the myocardium during global myocardial ischemia. Patients who received secondary cardioplegia (Group 2) were more likely to exhibit spontaneous defibrillation (12/15) than those in Group 1 (5/15) or Group 3 (6/15) (p less than 0.05). However, measurements of left ventricular performance and evidence of perioperative myocardial infarction were similar among all three groups. These data suggest that a standard technique of cold potassium cardioplegia alone should be the method of choice in elective, low-risk coronary bypass operations rather than this technique in combination with either of the other two more costly and complex methods evaluated in this study.

Hemolytic anemia secondary to erosion of a Silastic band into the lumen of the pulmonary trunk.

Abstract Hemolysis resulting from mechanical damage to red blood cells has been reported after cardiac valve replacement and after closure of septal defects with prosthetic materials. We have observed a child in whom a Silastic ® band placed around the pulmonary trunk eroded through the vessel wall and was stretched across the lumen causing pronounced hemolytic anemia.