David C. Sabiston

Performance status and outcome after coronary artery bypass grafting in persons aged 80 to 93 years

Although coronary artery bypass grafting (CABG) effectively eliminates or diminishes symptoms of myocardial ischemia, the overall performance status and functional outcome in elderly patients undergoing CABG is poorly documented. Therefore, 86 consecutive patients aged 80 to 93 years undergoing isolated CABG were reviewed. Preoperative, intraoperative, and postoperative characteristics and pre- and postoperative performance status (Karnofsky score) were examined. Forty patients (47%) were women, and most patients had highly symptomatic coronary artery disease with class III or IV angina in 94% and unstable angina in 90%. Significant co-morbid disease was present in 49% of patients, and cardiac catheterization revealed left main or 3-vessel disease in 74% of patients. The rate of significant in-hospital complications was 29%, with infection in 14%, stroke in 9%, and respiratory failure in 8% being most frequent. Median performance status (Karnofsky score) improved from 20 to 70% (p = 0.0001) with 89% of hospital survivors being discharged home. Factors associated with failure to achieve a successful functional outcome at discharge were presence of 1 or more preoperative co-morbid conditions (p = 0.048), preoperative myocardial infarction within 7 days of operation (p less than 0.01), and postoperative low cardiac output (p less than 0.01). Survival at 30 days, 6 months, and 3 years were 90, 78, and 64%, respectively. These data demonstrate that CABG can be offered to selected elderly patients with acceptable morbidity and mortality, marked improvement in performance status, and an acceptable quality of life.

Resecting and Grafting of Coronary Artery Aneurysm

A 31-year-old patient with symptoms suggesting acute myocardial infarction and subsequently found to have a large aneurysm of the circumflex branch of the left coronary artery is presented. This is thought to represent the first patient treated by resection and grafting of a coronary artery aneurysm by use of an interposed saphenous vein graft. The aneurysm was filled with friable blood clots, emphasizing the hazard of future embolizations. The etiology and indications for surgical resection are discussed.

Comparison of Human Ventricular Activation with a Canine Model in Chronic Myocardial Infarction

Ventricular activation was studied in 20 patients with ischemic heart disease at the time of surgery for myocardial revascularization. Because most of the activation studies in man were limited to recording of epicardial potentials, a canine model of chronic infarction was also studied. Pre- and postinfarction data were recorded in dogs and correlated with the anatomy of the lesions. Epicardial Q waves, when associated with delayed epicardial activation, were diagnostic of underlying infarctions in areas of the heart that did not normally exhibit Q waves. In areas normally containing Q waves, underlying infarction was associated with Q waves greater in duration than the normal range determined for those areas of the epicardium. The experimental model of chronic infarction showed epicardial delay to be due to slowed intramyocardial activation rather than to delay in Purkinje conduction. Correlations between electrical and anatomic data in two patients suggested that, within limits, the detailed relationships between infarction and activation established with the canine model could be applied to human infarction to understand the genesis of the epicardial potentials and the ECG. The technique was also felt to have a practical clinical application in selection of areas of myocardium for vascular implants or infarctectomy.

Quantitative radionuclide angiocardiography for determination of chamber to chamber cardiac transit times

Abstract A radionuclide method is described for determination of chamber to chamber cardiac transit times using only an intravenous injection. Using the Digital Autofluoroscope, counts of radioactivity from each square centimeter over the precordium were recorded onto computer tape at 0.23 second intervals after intravenous injection of 10 millicuries of 99mtechnetium pertechnetate. Computer analysis of counts grouped detector units with similar time responses into areas corresponding to discrete cardiac regions. From the resulting indicatordilution curves, appearance, peak and mean transit times were calculated for each cardiac region. Studies were obtained in 10 normal subjects, 14 patients with cardiac septal defects and left to right shunting and 20 patients with valvular stenosis or insufficiency. Among the latter patients, 8 had mitral stenosis and 8 had aortic insufficiency. Patients with a left to right shunt greater than 15 percent consistently demonstrated rapid pulmonary transit of tracer. In addition, specific abnormalities of curve configuration occurred in patients with a shunt greater than 30 percent. Transit times from the right atrium to left ventricle averaged 9.2 ± 1.2 seconds in normal subjects, 13.3 ± 2.2 seconds in patients with mitral stenosis and 14.6 ± 2.8 seconds in patients with aortic insufficiency. Pulmonary mean transit time was 6.6 ± 1.1 seconds in normal patients, 9.2 ± 1.7 seconds in those with mitral stenosis and 11.7 ± 3.1 seconds in those with aortic insufficiency. Pulmonary blood volume was 362 cc/m2 in patients with mitral stenosis and 508 cc/m2 in those with aortic insufficiency. These data suggest that pulmonary mean transit time was prolonged primarily by decreased cardiac output in mitral stenosis and by increased pulmonary blood volume in aortic insufficiency. The simple technique described consistently provided hemodynamic data that appear to be useful for diagnosis and management of cardiac diseases.

Studies of Blood Flow in Aorta-to-Coronary Venous Bypass Grafts in Man

Pressure-flow measurements were obtained from the vein graft of 57 patients undergoing a single aorta-to-coronary bypass procedure. The flow contour was similar to phasic left coronary artery flow in dogs except for a transient increase during systole possibly related to elongation of the graft. Flow was highest during bypass and decreased to a stable value 30 min after bypass. In 42 patients, flow at this time was 35+/-2 cm(3)/min (mean+/-sem).NO CORRELATIONS WERE DEMONSTRATED BETWEEN FLOW AND THE FOLLOWING: left vs. right grafts, presence or absence of collaterals, total vs. partial block, or the presence or absence of ventricular dyskinesis. In 32 patients, no correlation between these anatomic findings and the presence of reactive hyperemia was demonstrated. In 17 patients, occlusion of the graft for 10 sec resulted in a mean 51.5% flow debt repayment. In nine patients, injection of 0.3 mug of isoproterenol into the graft increased flow from 45+/-6 to 69+/-9 cm(3)/min within 4-7 sec without changes in rate, pressure, time derivative of left ventricular pressure (LV dp/dt), or left ventricular end diastolic pressure (LVEDP). Maximum increases to 87+/-10 cm(3)/min occurred 12-20 sec after injection with concomitant changes in these parameters. Intravenous infusion of norepinephrine did not change vascular resistance, whereas phenylephrine did. In six patients, injection of 0.2 mug of norepinephrine into the graft decreased flow from 49+/-6 to 25+/-5 cm(3)/min within 5-8 sec. Intravenous infusion of 0.15 mg of nitroglycerin decreased coronary vascular resistance from 2.7+/-0.4 to 2.3+/-0.3 mm Hg/cm(3) per min. In five patients, 0.12 mg of nitroglycerin injected into the graft increased flow from 46+/-7 to 71+/-13 cm(3)/min and lasted 20-40 sec.

Recognition of Postoperative Acute Myocardial Infarction Application of Isoenzyme Techniques

Routine enzymatic and electrocardiographic diagnosis of postoperative acute myocardial infarction (AMI) is frequently inconclusive. The detection and quantitation of isoenzymes of lactate dehydrogenase (LDH) and creatine phosphokinase (CPK), especially the cardiac-specific CPK-MB isoenzyme, have allowed earlier recognition of AMI in nonsurgical patients. Serial monitoring with these methods has been utilized during the postoperative period in 20 noncardiac surgical patients and 100 patients undergoing coronary artery bypass grafting (CABG).In the noncardiac surgery group, both isoenzymes were accurate in diagnosing AMI in the early postoperative period. Of the 100 patients in the CABG group, CPK-MB appearance in 21 correlated with AMI by electrocardiogram. The absence of CPK-MB postoperatively in 49 patients permitted a 73% incidence of new ECG abnormalities to be effectively resolved. Autopsy confirmation of AMI was obtained in two patients with nondiagnostic ECG, but with elevated CPK-MB. The elevated CPK-MB without ECG evidence of AMI in the remaining patients could possibly be explained by varying degrees of myocardial damage produced by intraoperative cardiac manipulation. These data demonstrate the value and sensitivity of CPK-MB isoenzyme determinations in the early recognition of postoperative acute myocardial infarction.

Hemolytic Anemia Following Prosthetic Valve Replacement

Ten patients with marked hemolytic anemia secondary to prosthetic cardiac valve replacement are presented. Although the etiology of this disorder is not understood, available evidence supports the concept of blood destruction secondary to turbulence around valves as the primary factor. These studies illustrate the technical difficulties associated with reoperation and the disappointing results which often follow. Emphasis is placed on the role of iron replacement and folic acid therapy in association with moderate reduction in exercise. This regimen has produced gratifying results in the management of these patients.

Quantitation of Left-to-right Cardiac Shunts with Radionuclide Angiography

A quantitative radionuclide angiogram technique using an intravenous injection of technetium-99m (Tc-99m) pertechnetate is described for quantitation of left-to-right shunts in the central circulation. Data analysis assumes exponential indicator clearance from normal cardiac chambers by dilution. A late prolongation of tracer disappearance compared to the initial clearance rate indicates an abnormally early return of indicator to the cardiac chamber. Patients with left-to-right shunts demonstrate prolonged clearance of radioactivity from all cardiac chambers distal to the site of shunt. The magnitude of curve distortion is quantitatively related to the size of shunt, and counts recorded from the right lung are used for shunt quantitation. Quadratic regression analysis of data from 21 patients with left-to-right shunts and eight normal subjects demonstrated a correlation coefficient of 0.951 between measurements of left-to-right shunts by the radionuclide and by the Fick method. Observations on 14 patients with aortic or mitral valve disease revealed this method of shunt evaluation to be of limited value in the presence of severe cardiac valvular disease. However, the method permits detection of left-to-right shunts that are too small to be diagnosed by the Fick method and accurately quantitates shunts which are not at either extreme in size and flow. This technique appears to be potentially useful for the initial diagnosis and serial evaluation of patients with these disorders.

Fusion of the Left Aortic Cusp to the Aortic Wall with Occlusion of the Left Coronary Ostium, and Aortic Stenosis and Insufficiency

The case of a 16-year-old girl with a unique anomaly of the coronary arterial tree is presented. This report concerns the first known case of isolated adherence of the left coronary aortic valve cusp to the aortic wall. This produced total obstruction of the left coronary artery ostium, angina pectoris, syncope, aortic stenosis, and aortic insufficiency. Freeing the adherent cusp from the aortic wall restored patency of the left coronary artery, relieved the aortic insufficiency, and resulted in disappearance of the angina pectoris and syncope. This case adds to the growing spectrum of nonatherosclerotic coronary abnormalities which are capable of producing myocardial ischemia.

Pulmonary arterial impedance after single lung transplantation

Single lung transplantation (SLT) is emerging as definitive therapy for end-stage pulmonary disease of varying etiology, yet a complete description of the hemodynamic properties of the transplanted lung has not been reported. In this study, Fourier analysis was used to calculate the pulmonary arterial (PA) impedance spectrum before and immediately after SLT to define precisely the pulmonary pressure-flow relationship. Median sternotomies were performed in 18 dogs (donors): an ultrasonic flow probe was placed around the PA and micromanometers were placed in the PA and left atrium (LA). Control PA pressure and flow (PAQ) and LA pressure were measured during transient occlusion of the right PA. The lungs were harvested using cold modified Euro-Collins solution for preservation. After thoracotomy and pneumonectomy, left SLT was performed in 18 recipient dogs with a mean ischemic time of 179 +/- 6 min. After reperfusion for 1 hr, PA pressure and flow data were again collected. Characteristic impedance (Z0), a measure of resistance to pulsatile flow, was compared to input resistance (Rin), a measure of resistance to mean flow, and pulmonary vascular resistance (PVR), the conventional index. Rin is defined as the zeroth harmonic of the impedance spectrum and Z0 as the mean of impedance moduli from 2-12 Hz. All recipients survived transplantation. Both PVR and Rin increased significantly after transplantation (11 +/- 1 vs 19 +/- 3 Wood U, P less than 0.05, and 1352 +/- 121 vs 1964 +/- 244 dyne.sec.cm-5, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)