ABSTRACTS

FAMILIAL ATRICJVENTRICULAR CONDUCTION DEFECT METABOLIC SURGERY IN THE HYPEBLIPOPROl’BINEMIA Syed rbhiuddin, !~Q: Henry Lynch, !fD; alichael Sketch, !.iD; Richard B. Moore, MD; Richard L. Varco, MD, PhD; Henry Anne Krush, MS; Stenhen Carter: and Vincent Runco , YD; Buchwald, MD, PhD, FACC; University of Minnesota, Creichton Ilniversity, omaha, Nehraska. Minneapolis, Minnesota

We have recently reported familial incidence of pro- gressive A.V. conduction defects resulting in complete heart block (CHB) in 3 generations. This report des- cribes the distinctive ECG features of this new syndrome as well as the hemodynamic, aneiogranhic and morphologic findings. The site of block was demonstrated by His bun- dle electrograms in some subjects. Hedical genetic eval- uation has been made in 502 members of which 208 had ECC studies. EC6 confirmation of varying degrees of AV block was noted in 31 while 5 members were thought to he affected by history. ECC features, common to all affect- ed members, were 1) Progressive increase in AV conduc- tion delay culminating in CHB usually in the 3rd and 4th decade, 2) Normal QRS configuration and duration, 3) Normal QT intervals, 4) Pcor R wave progression in right precordial leads simulating anterosental infarction. Three members have undergone cardiac catheterization studies including coronary angiogranhy which were normal. ‘fyocardial tissue analysis in two memhers revealed no morphologic or histochemical abnormalities. His bundle electrograms, during transient sinus rhythm, revealed nrolonged P-A and P-H intervals. II-V was normal. In one subject ‘?I’$’ activity was recorded and revealed prolonpa- tion of P-N as well as N-H intervals. These studies in- dicate that the nathological process is localized to atrial-atrioventricular conduction pathways and early recognition and treatment with cardiac Pacemakers should he associated with better prognosis than other forms of adult onset comnlete heart block.

THE EFFECT OF CURRENT PULSES ON VENTRICULAR FIBRILLATION THRESHOLD MEASUREMENTS by E.Neil Moore, D.V.M., Ph.D., F.A.C.C., Joseph F. Spear, Ph.D., and Leonard Horowitz, M.D., Schools of Veterinary Medicine and Medicine, Uni- versity of Pennsylvania, Philadelphia, Pennsylvania.

Experiments were performed on the hearts of open chest anesthetized dogs to determine the effects of current delivered as a single pulse or train of pulses to the myocardium during the vulnerable period. Following the pulse(s), the time course of recovery of excitability was determined at various regions of the myocardium. Increasing the current intensity resulted in increased temporal dispersion in recovery of excitabiIity of the myocardium. This increase in tempora1 dispersion was associated with a decrease in fibrillation threshold. The temporal dispersion in recovery following delivery of a current train was increased by coronary artery occlusion and decreased by intravenous administration of lidocaine. These studies suggest that the technique of current applG cation to assess vulnerability operates in the following way: increasing the intensity of current delivered during the vulnerable period results in progressive increases in the degree of inhomogeneity in the recovery of the myo- cardium until a level is attained which allows multiple asynchronous reentry and fibrillation. Interventions which increase or decrease the intrinsic amount of inhomogeneity modify the amount of “extra inhomogeneity” that the current pulses must add during a fibrillation threshold determination to bring the myocardium to a level for fibrillation. These data also suggest that the myocardium may be more vulnerable following premature beats (PVC) evoked by a malfunctioning pacemaker than following spontaneous PVC’s at the same coupling interval,

Partial ileal bypass greatly alters the dynamic equilib- rium of body cholesterol with resultant increased choles- terol turnover and lowered plasma cholesterol level. Since 1963 we have used this therapy in lOl(type II, III, & IV) patients (66 male, 35 female) ranging in age from 7 to 63 years (decade distribution: first-l, second-8, third-8, fourth-14, fifth-43, sixth-25, seventh-2). Sur- gery was prophylactic (no evidence of coronary disease by history, ecg, or arteriography) in 20 patients and thera- peutic in 81. All patients had appropriate diet therapy for at least 3 months before surgery. Surgery has been effective in patients having poor or no response to diet or drugs. All patients had significant plasma cholesterol reductions, averaging 40% (excluding 3 homorygous type II patients who had reductions of 13, 15, and 16%). The av- erage reductions up to 5 years (excluding the 3 type II homozygotes) compared to the preoperative post-dietary baseline (varies with n followed) was: 3 mos, 40% (362 to 216 mg%); 1 yr, 39% (355 to 218 mg%); 2 yr, 38% (346 to 214 mg%); 3 yr, 41% (365 to 214 mg%); 4 yr, 36% (353 to 227 mg%); 5 yr, 40% (342 to 204 mg%). Patients with sig- nificantly elevated triglycerides had marked reductions (30-60% range) after surgery; type II-A patients had an average 28% increase (117 to 149 mg%). The plasma lipid changes appear to be permanent; no escape has been seen. Operative mortality was less than 1%. Morbidity has been low; side effects are limited to diarrhea, transient with few exceptions. Eleven of the 81 patients with coronary atherosclerosis have since died, 9 of myocardial infarc- tion. In our experience partial ileal bypass is the single most effective therapy in type II, III, and IV hyperlipoproteinemia.

ARRHYTRlIC INDICATORS OF LONG TERM SURVIVAL AND LATE DEATH AFTER \lYDCARDIAL INFARCTION Arthur J. Moss, MD, FACC; John DeCamilla; William Hoff- man; Fredrick Engstrom The University of Rochester Medical Center, Rochester, New York

In order to characterize those pts. who are at high risk of late cardiac death after myocardial infarction (MI), data were obtained prospectively on 100 patients (mean age 58 years; 79 males, 21 females) hospitalized with MI. 67 of the 100 pts. had one or more VPBs on a pre-discharge six-hour ECG tape recording. VPBs were characterized in terms of frequency (F) (#VPBs/lOOO nor- mal beats), prematurity (P) (RR’/QT), and presence (1) or absence (0) of bigeminy/pairing (B/P) and ventricular tachycardia (VT). 55 pts. survived and 12 died from re- peat coronary events during a two year follow up. 13 pro- spectively obtained variables including ECG and VPB data, severity of MI (Peel and Norris indices) and age were subjected to step-wise discriminant analysis to obtain the best separation between those who survived and died. Discriminant scores (DS) which included only four vari- ables in the function (DS = -1.7 x B/P - 0.06 x Age + 1.8 x P - 0.01 x F + 3.0) provided significant separa- tion between the two groups. A score below zero correct- ly identified 11/12 pts. who died (av. score -1.2) and a score above zero properly categorized SO/55 survivors (av. score +l.l). The inclusion of YI severity, VT and sex in the discriminant function did not improve the accuracy of separation. From the discriminant scores the probability of survival and death was determined for each patient. Conclusion: a discriminant combination of selective VPB data and age can be used to identify and characterize those pts. at high risk of subsequent cardiac death.

148 January 1973 The American Journal of CARDIOLOGY Volume 31