W. Gerald Austen

Cardiovascular Response to Large Doses of Intravenous Morphine in Man

Abstract Large doses of intravenous morphine (0.5 to 3.0 mg per kilogram of body weight) were used alone or in combination with inhalation anesthetic agents for anesthesia in over 1100 patients undergoing open-heart surgery. Morphine, 1 mg per kilogram, was administered intravenously to seven subjects with aortic-valve disease and eight without major heart or lung disease. The cardiac subjects had higher control pulse rates and lower control stroke indexes than the normal subjects. In the cardiac but not in the normal subjects, significant increases in cardiac index, stroke index, central venous pressure, and pulmonary-artery pressure, and a significant decrease in systemic vascular resistance, were observed after morphine was administered, suggesting that large doses of morphine may be used with safety in patients with minimal circulatory reserve.

Prosthetic Valve Endocarditis Analysis of 38 Cases

In 38 cases of prosthetic valve endocarditis, 19 were early cases (onset ≦ 60 days after insertion of prosthesis) and 19, late cases (onset ≧ 60 days). Nine late cases had onsets 12 to 53 months after surgery. The sources or predisposing factors in late cases included dental disease or manipulation; genitourinary tract procedures; and skin, urinary, or wound infections. In contrast, most early cases were secondary to complications of operation. Streptococci were the most common organisms causing late endocarditis, whereas staphylococci were most common among early cases. Four of the six patients who survived early onset were treated with antibiotics alone; the others, with antibiotics plus reoperation. In contrast, seven of the 11 late cases that survived were treated with antibiotics alone; the other four, with antibiotics plus reoperation. The lower mortality (42% vs 68%) in the late group probably reflects the less virulent infecting organisms and the better clinical condition of the hosts. Regardless of whether prosthetic valve endocarditis occurs early or late, intensive and prolonged administration of appropriate antibiotics together with aggressive surgical reintervention in selected situations appears necessary for cure. Any patient who has a prosthetic valve and undergoes any procedure likely to produce bacteremia should receive antibiotic prophylaxis in an attempt to prevent late endocarditis.

Clinical and Hemodynamic Results of Intraaortic Balloon Pumping and Surgery for Cardiogenic Shock

The AVCO balloon pump has been employed in treating 40 patients with cardiogenic shock from acute myocardial infarction (CS-MI). All patients were given a trial of medical therapy with hemodynamic monitoring. The time from the development of shock to institution of intraaortic balloon pumping (IABP) was less than 24 hours in all but nine patients. Prior to IABP the mean hemodynamic values were: cardiac index (CI) 1.7 liters/min/m2; mean arterial pressure (MAP) 66 mm Hg; pulmonary artery wedge pressure (PAW) 22 mm Hg. After 24-48 hours of IABP the CI and MAP had increased 0.8 liters/min/m2 and 8 mm Hg, respectively, and the PAW had decreased 4.8 mm Hg. During IABP the shock syndrome was reversed in 31 patients. Four of 25 patients treated with IABP alone survived to be discharged, but two have died from subsequent infarctions. Because of the persistent high mortality, 15 patients judged unable to survive off IABP have undergone emergency surgical procedures with IABP continuing during preoperative angiography and postoperatively. Six were long-term survivors. It is concluded: (1) IABP is a safe, effective means of supporting the circulation in CS-MI; (2) IABP alone will improve survival in some patients; (3) IABP can provide circulatory support during angiography and the perioperative period in patients requiring revascularization for survival; and (4) some patients with CS-MI have myocardial necrosis too extensive to permit survival without permanent circulatory assistance or total cardiac replacement.

Acute Traumatic Disruption of the Thoracic Aorta: A Ten-Year Experience

During a ten-year period, 44 patients were treated for acute traumatic disruption of the thoracic aorta. Of the 44 patients, 21 had operative repair within 48 hours of injury (Group 1); 14 patients had operative therapy electively delayed for 2 to 79 days (Group 2); 5 had operative therapy electively delayed indefinitely (Group 3); 2 had immediate operative repair when a delayed diagnosis was made at 21 and 56 days, respectively (Group 4); 1 patient died during angiography and 1 refused operation (Group 5). Mortality was as follows: Group 1, 24%; Group 2, 14% Group 3, 0; Group 4, 100%; and Group 5, 100%. All operative deaths occurred in the subgroup of 23 patients in whom left heart bypass was utilized. Immediate operative intervention with a heparinized shunt is preferable as soon as the diagnosis of thoracic aortic disruption has been established, but elective delay of operation in patients with severe concomitant injuries can be achieved safely with beta blockade and antihypertensive therapy.

Long-term survival of patients with treated aortic dissection

Retrospective data on the treatment of aortic dissection at the Massachusetts General Hospital from 1963 to 1978 are reported. During this period, 160 patients with spontaneous aortic dissection were treated by definitive medical or definitive surgical therapy. Patients were classified according to type (proximal versus distal) and duration (acute versus chronic) of dissection. Long-term follow-up (mean 48 months, range 1 to 147) was available in 156 cases. Hospital and late survival in each of the categories of dissection were evaluated in relation to those features of the dissection itself and of the subsequent therapy that correlated with ultimate survival. Results show that: 1) chronic presentation was the most significant determinant of both hospital and late survival; 2) in acute dissection, prognosis was determined largely by the presence or absence of major complications, regardless of ultimate therapy; the only complication without adverse effect on survival was aortic insufficiency; 3) late survival after discharge from the hospital was similar for patients with all types of dissection and modes of therapy; and 4) the incidence of late complications from aortic dissection was lower than previously reported. Thus, the success of early definitive medical and surgical treatment was sustained on long-term follow-up.

Mitral valve reconstruction versus replacement for degenerative or ischemic mitral regurgitation

Between January 1985 and June 1992, 263 consecutive patients had mitral valve reconstruction (133 patients) or replacement (130 patients) for degenerative or ischemic mitral regurgitation. The two groups were similar in sex, age, prior infarctions or cardiac operations, hypertension, angina, and functional class. Both groups were similar in mean ejection fraction, pulmonary artery pressure, cardiac index, and incidence of coronary artery disease. More reconstruction than replacement patients had ischemic etiology (22 [16%] versus 12 [9%]; p = not significant), and fewer reconstruction patients had ruptured anterior leaflet chordae (9 [7%] versus 39 [30%]; p < 0.01). More reconstruction than replacement patients had concomitant cardiac procedures (67 [50%] versus 59 [45%]; p = not significant). Hospital death occurred in 4 reconstruction patients (3%) and 15 (12%) replacement patients (p < 0.01). Median postoperative stay was shorter in reconstruction patients (10 versus 12 days; p = 0.02). Late valve-related death occurred in 3 reconstruction patients (2%) and 8 (6%) replacement patients (p = 0.08). Six-year actuarial freedom from thromboembolism was 92% for the reconstruction group and 85% for the replacement group (p = 0.12). Freedom from all valve-related morbidity and mortality was 85% for the reconstruction patients and 73% for the replacement patients (p = 0.03). Significant multivariate predictors of hospital death were age, mitral valve replacement, functional class, congestive heart failure, no posterior chordal rupture, and nonelective operation. Mitral valve reconstruction, when technically feasible, is the procedure of choice for degenerative or ischemic mitral regurgitation because of significantly lower hospital mortality and late valve-related events.

Surgery for post-myocardial infarct ventricular septal defect.

Forty-three patients (mean age 62 ± 1 years) were treated for ventricular septal defect (VSD) secondary to myocardial infarction. Whenever possible, operation was postponed until six weeks post-onset chest pain. However, hemodynamic instability, evidenced by cardiogenic shock, refractory pulmonary edema, or a rising blood urea nitrogen (BUN) forced operation in 21 patients within 21 days post-infarct (Group I). In seven patients operation was performed three to six weeks post-infarct (Group II). In only eight patients could operation be delayed beyond six weeks post-infarct (Group III). Clinical deterioration, once begun, progressed rapidly, and could be reversed only temporarily by intra-aortic balloon pumping, used in 26 patients for safe conduct of cardiac catheterization and for peri-operative hemodynamic support. Hospital survival was achieved in 24 of the 36 operated patients (66%). In Group I patients, ten of 21 survived. In Group II, six of seven survived. In Group III, eight of eight patients survived. There have been five late deaths with a mean follow-up of 41 months in survivors. Improved survival has been achieved recently by the greater use of prosthetic material to replace necrotic muscle and by a transinfarct incision regardless of infarct location. Operative mortality before 1973 was 47%; mortality after 1973 was only 18%, with a concomitant reduction of mortality (30%) even in Group I patients.

Autopsy Findings with Permanent Pervenous Pacemakers

Of 130 patients who received permanent pervenous pacemakers in the last 2 years at the Massachusetts General Hospital, 21 have died; complete postmortem data are available on seven who died 5 days to 18 months after insertion of the pacemaker. No deaths were related to pacemaker malfunction. No patient received routine anticoagulant therapy. The intracardiac portions of all pacemaker electrodes were 30 to 80% endothelialized. In three cases tiny, organized mural thrombi formed on these sheaths, but none appeared to give rise to pulmonary emboli. All pacemaker electrode tips were wedged firmly beneath the trabecular system of the right ventricular apex and elicited varying degrees of local fibrous tissue reaction. Further focal fibrotic attachments occurred in the right atrium and superior vena cava. Although in four cases the electrodes adhered to the chordae tendineae, the long-term presence of an electrode did not appear to compromise tricuspid valve function. Late removal of an electrode may be hazardous because of its firm attachments to the endocardium and tricuspid valve.

Effects of Intra-Aortic Balloon Counterpulsation on Cardiac Performance, Oxygen Consumption, and Coronary Blood Flow in Dogs

The effect of intra-aortic Counterpulsation (IACP) with a balloon upon myocardial oxygen consumption (MV·o2), coronary blood flow (TCF), and left ventricular performance was studied in 23 anesthetized canine right heart bypass preparations at constant heart rate and cardiac output. In nonhypotensive, nonTCF-limited preparations, IACP produced a fall in left ventricular peak systolic pressure (LVP) and a decrease in MV·o2 (-1.1 ± 0.2 (SE) ml/min/100 g LV). In these animals there was little steady state change in TCF (-5.6±5.9 ml/min), secondary to autoregulation by the coronary vascular bed. Left ventricular end-diastolic pressure (LVEDP) fell if elevated but exhibited little change if initially normal. However, in hypotensive preparations, in which left ventricular performance was substantially limited by a decreased TCF, IACP produced a striking increase in TCF (+40.9 ± 8.6 ml/min) accompanied by an increase in MV·o2 (+1.2±0.3 ml/min/100 g LV). Elevated LVEDPs fell substantially toward normal. Directiona...

Late prosthetic valve endocarditis: clinical features influencing therapy.

To assess the clinical features which might influence therapy, we studied 43 patients with late prosthetic valve endocarditis (LPVE). Twenty patients (47 per cent) survived. Of patients with streptococcal LPVE 61 per cent (11 of 18) survived compared to 36 per cent (nine of 25) of the patients with nonstreptococcal LPVE (p less than 0.10). Among patients with new regurgitant murmurs 33 per cent (nine of 27) survived versus 69 per cent (11 of 16) with such murmurs (p less than 0.03). Of patients with moderate to severe congestive heart failure (CHF) 16 per cent (three of 19) survived compared to 71 per cent (17 of 24) with mild or no CHF (p less than 0.001). The concurrence of two of these three features, i.e., nonstreptococcal etiology, a new regurgitant murmur or moderate to severe CHF, was associated with a mortality rate of 50 to 90 per cent. Persistent fever during therapy, a regurgitant murmur, atrioventricular conduction disturbances and relapse frequently reflected myocardial invasion. In view of the poor outcome with medical therapy and late reoperation, early surgical intervention should be considered when two of the three features noted are present or when myocardial invasion is suspected.