ABSTRACTS

Factors Affecting Operative Risk and Prognosis for Long-Term Survival in Human Heart Transplantation

D. A. CLARK, MD; J. S. SCHROEDER, MD; R. B. GRIEPP, MD; E. B. STINSON, MD; NORMAN E. SHUMWAY. MD, FACC. DONALD C. HARRISON, MD, FACC, Stanford, California

Twenty-five patients have undergone cardiac trans- plantation at Stanford since January 1968. Actuarial survival rates are 420/C at 6 months and 33% at 12 and 18 months. Three patients died within 72 hours, all secondary t’o progressive right heart failure in the allograft caused by markedly elevated and irreversible pulmonary vascular resistance (Group I). Nine patients died of rejection or infection within 2 months of opera- tion (Group II). Twelve patients were discharged in satisfactory condition approximately 60 days after transplantation (G,roup III). One patient died at 22 days from a cerebral vascular accident. Groups II and III differ statistically with respect to age (53 vs. 47 years) and length of known heart disease (97 vs. 50 months). Other indexes measured preoperatively offer no criteria to predict long-term survival.

Long-term follow-up studies of the 12 patients who were discharged from the hospital show 80% survival at 6 months and 70% at 12 and 18 months. The effect of chronic rejection on the cardiac allograft appears to be the limiting factor in long-term survival, and in our 12 patients the evidence for this includes the fol- lowing observations : Sinoatrial node malfunction sec- ondary to an obliterative arteritis affecting the atrio- ventricular nodal artery resulted in the death of 1 pa- tient at 8 months from Stokes-Adams attack. H.olter monitoring of another patient revealed the presence of marked sinus bradycarclia successfully treated with de- mand pacemaker. One patient died suddenly of an acute posterior myocardial infarction at 21 months. Autopsy results revealed an accelerated atherosclerosis in the coronary arteries of the allograft. Maximal exercise studies in other surviving patients have indicated ob- jective evidence of myocardial ischemia in spite of ex- cellent function of the allograft as shown by routine cardiac catheterization 1 year after transplantation.

Quantification of the Extent of Myocardial Infarction by Radionuclide Imaging of the Myocardium

MALCOLM COOPER, MD; PETER J. HURLEY, MD; T. K. NATARAJAN; FREDERICK E. LOMAS, MD; KEN POGGENBERG; HENRY N. WAGNER, Jr., MD, Baltimore, Maryland and Oak Ridge, Tennessee

Knowledge of the site and extent of nonfunctioning myocarclial tissue should prove to be helpful in the clin- ical management of patients with acute or chronic ischemic heart disease. Electrocardiography and serum enzyme determinations have proved of value in the di- agnosis of myocardial infarction, but there has been no easy way to determine the extent of involvement.

Using the radioactive tracer potassium-43 chloride with the gamma scintillation camera or a rectilinear scanner, we have been able to delineate areas of myo- cardial infarction or fibrosis. Twenty-eight studies were made of 7 normal dogs, 5 selected normal persons

and 7 patients, 5 with acute myocardial infarction and 2 with chronic ischemic heart disease. In addition to obtaining a picture of the intact muscle mass of the myocardium, we recorded the data on tape which per- mitted subsequent quantitative analysis by means of a small general purpose computer. The size of the defects together with the relative activity in different regions of the myocardium could be determined.

The nuclicle potassium-43 has a physical half-life of 22.4 hours. The whole-body absorbed radiation dose from the 0.5 mc dose of 43K is approximately 0.35 rad for a 70 kg man. Further studies are in progress to evaluate the usefulness of this technique in patients with coronary heart disease.

The Effect of Selective Cardiac Beta Adrenergic Blockade on the Hypotensive Effect of Hydralazine

A. S. DAHR, MD; C. F. GEORGE, MB, London, England

A selective cardiac aclrenergic beta blocker (such as ICI 50172: Practolol) is expected to increase the hypo- tensive effect of hydralazine (HZ), by blocking the reflex sympathetic cardiac stimulation. Nine mongrel clogs, anesthetized with thiopentone sodium, 30 mg/kg intravenously, and ventilated by a respirator were used. Polyethylene cannulas were inserted into the cephalic vein and femoral artery for drug administration and blood pressure monitoring. The heart rate was moni- tored by a rate meter triggered by the R wave of the electrocardiogram. The changes in heart rate (HR), systolic blood pressure (SBP) and di,astolic blood pres- sure (DBP) after the intravenous administration of HZ, 0.1 mg/kg, 0.3 mg/kg, 0.6 mg/kg and 1.0 mg/kg in order, were measured. Observations were made before and were repeated after the intravenous administration of Practolol (PL) , 2 mg/kg. PL blocked the increase in HR caused by HZ, 0.1 mg/kg and 0.3 mg/kg.

HZ given in the above order lowered SBP by 5.7 + 3.7; 5.2 2 1.7; 10.7 * 2.5; and 27.0 2 9.8 mm Hg before PL, and by 2.4 & 1.8; 1.2 & 1.3; -5.8 rtr 1.9 and 24.3 4 8.9 mm Hg after PL. HZ lowered DBP by 4.2 & 0.9 ; 8.6 f 2.2; 10.8 f 1.8 and 33 + 8.6 mm Hg before PL, and by 4.6 * 2.9; 3.0 +- 3.5; 5.2 2 1.6 and 21.6 & 8.9 mm Hg after PL. The hypotensive effect of HZ was not increased by PL, rather it was lessened. This suggests that the reflex sympathetic adrenergic cardiac stimula- tion caused by HZ peripheral vasodilator action does not offset the hypotensive effect of HZ.

The Effect of lsoproterenol (ISP) on the Electrocardiogram in Patients with Intracranial Lesions

F. S. DAOUD, MD: BORYS SURAWICZ, MD, FACC, Lexington, Kentucky

T wave abnormalities attributed to intracranial lesions were transiently abolished ‘after infusion of 4-6 pg ISP/min for 30-60 seconds in 7 patients. None of these

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