ABSTRACTS

Low Energy Versus High Energy Defibrillation in the Treatment of Out-of-Hospital Ventricular Fibrillation. A Preliminary Report. W.Douglas Weaver,MD,FACC;Leonard A.Cobb,MD,FACC;Michael K. Copass,MD;Alfred P.Hallstrom,PhD,University of Washington, Seattle, WA.

The efficacy of defibrillation using 175J was prospective- ly compared to 320J in 95 victims of ventricular fibrilla- tion (VF) treated outside the hospital. By randcm alloca- tion, 46 patients (pts) received 175J and 49 received 320J for the first two shocks; all subsequent shocks were 320J in both groups. Ten of the 175J group (22%) and 8 of the 320J group (16%) persisted in VF through two shocks. Twenty-nine pts in each group were resuscitated and trans- ported to the hospital. Fourteen of 38 pts (37%) in the 175J group and 12 of 41 (29%) in the 320J group survived and returned home (8 in each group are still hospital- ized). The 175J group received an average of 4.7 shocks compared to 3.4 in the 320J group (p< 0.05); but this difference occurred only in non-resuscitated pts (6.6 vs 4.0 shocks in the 175J vs the 320J group respectively, p< 0.025). Pts discharged alive (both groups) received fewer shocks than did those who were resuscitated and later died in the hospital, (2.4 vs 4.6, p< 0.005). At the end of the two shock trial, the ECG showed the following rhythms in the 175J and 320J groups: VF 35% vs 20%; asys- tale 7% vs 20% (p< 0.05); idioventricular 15% vs 16%, and supraventricular 43% vs 43%. Following the first two shocks, 3 pts (7%) in the 175J group compared to 10 (20%) in the 320J group had demonstrated high degrees of AV block (p< 0.05).

We conclude that two low energy shocks appear to be safe in the treatment of out-of-hospital VF, that outcome appears at least as good as that obtained with 32OJ, and that there may be less cardiotoxicity as measured by resulting asystole and AV block.

TWO DIMENSIONAC ECROCAFDIOGRAPHY CAPDIOPULf4ONARY RESUSCITATION IN

OF THE HEART DURING MAN MD; Edward.Shapiro, MD, Stuart Rich, MD; Hershel L. Wix,

University of Chicago, Chicago, Illinois.

Recent animal studies have challenged the notion that corn pression of the heart between the sternum and spine causes blood flow during closed chest CPR. We performed 2-D echocardiography (ZDE) within 20 minutes after the initi- ation of CPR in four patients (ages 58-84 yrs., 3 with coronary artery disease, 1 with congestive cardiomyopathy) who had cardiac arrest while in the intensive care unit. Each patient had arterial pressure monitoring that con- firmsd the effectiveness of the CPR. None of the patients survived resuscitation. Analysis of the 2DE showed that the mitral and aortic valves were open simultaneously dur- ing the compression phase, suggesting blood flow directly from the lungs to the AO. Blood flow into the RV, as seen with saline bubble contrast, occurred during the relaxa- tion phase. Measurements of the heart made from the para- sternal long-axis view showed: 1) no appreciable reduc- tion in LV dimension during compression (average 2.8%, range l-9-3.8%); 2) the reduction in LA and RV outflow tract dimension with chest compression averaged 22.8% and 52.7% respectively. Our study confirms that the flow of blood from the heart generated by chest compression during CPR is not caused by compression of the LV and supports the evidence that blood flow during CPR results from changes in intrathoracic pressure. Blood flow from direct compression of tbe LA and A0 may be a factor in some patients.

MGNDAY, MARCH 16, 1961 PM PHARMACOLOGY: CALCIUM ANTAGONISTS I 2:00-3:30

THE PLACEBO RESPONSE IN VASOTONIC ANGINA-A CRITICAL FACTOR IN DRUG TRIAL DESIGN. Rose M. Robertson, MD, FACC; Yvonne Bernard, RN; David Robertson, MD, Vanderbilt Medical Center, Nashville TN.

Many agents have been thought efficacious in vasotonic an- gina because a decrease in ischemic episodes followed their administration. We analyzed more than 1500 episodes of VA in 10 patients(pts) (ages 38-72;6 female,4 male) ad- mitted to hospital for diagnosis and therapeutic trials. All pts had chronic recurrent episodes of myocardial is- chemia which were not preceded by a rise in heart rate or intra-arterial pressure. Coronary anatomy ranged from an- giographically normal (1 pt) to 90% stenosed (1 pt), with 7 pts having 30-50% narrowings. We performed all trials in a random-order, double-blind, placebo(PLA)-controlled fa- shion, with continuous ECG recordings throughout. An ini- tial PLA run-in period of 2-4 days was followed by multi- ple cross-avers back to PLA between trials of therapeutic agents. We tabulated the frequency of ischemic episodes on initial PLA days and during days of later PLA periods more than 5 half-lives removed from active agents. Two patterns emerged. Two pts had stable VA, with 12-37 episodes of is- chemia/day, unchanging over 6 weeks of observation. All other pts had a gradual decrease in the frequency of epi- sodes, often mimicking a therapeutic response. In 6 of 8, the decrease on PLA day 2 ranged fro 20-100X. By the third PLA period, 4 pts had complete remission of episodes. Seven of the 8 pts had no more than 2 episodes/day by the fourth PLA period. The mean decrease in the daily number of ischemic episodes over the total hospital stay was 91% for these B pts, from a mean of 15/day to a mean of Z/day, (p<O.O5). We conclude that complete or near-complete re- missions are characte.ristic of vasotonic angina. An in- herent decrease in the frequency of ischemic episodes may easily confound the interpretation of therapeutic trials.

A COMPARISON OF VERAPAMIL AND NIFEDIPINE IN PATIENTS WITH PRINZMETAL'S VARIANT ANGINA PECTORIS. SM Johnson, MD, DR Mauritsond MD, JT Willerson, MD, FACC, LD Hillis, MD, FACC, U of Texas Health Science Center, Dallas, TX. The present study was performed to assess the relative efficacies of verapamil (V), nifedipine (N), and placebo (P) in the therapy of patients (pts) with variant angina pectoris (VAP). In 10 pts (6 men. 4 women, mean age.52 yrs) with VAP, V (400*80 a&day, mean*SD),N (82*31 s/day) and P each were administered for 2 months. Eight of the 10 pts were maintained throughout the 6 months of study on a stable dose of isosorbide dinitrate (138*56 mglday). Prior to study, all had cardiac catheterization: 8/10 had no fixed coronary artery disease (CAD), 1 had 1 vessel CAD, and 1 had 3 vessel CAD. TWO of the 10 had been re- suscitated from sudden cardiac death prior to study. Dur- ing each 2-month period, the following were quantitated: (1)chest pains/week (wk). (2)nitroglycerin used/wk, and (3)required hospitalizations (HOS) for clinical instabi- lity. With both V and N, the number of chest painslwk and the number of NTG used/wk were less than with P. During P, 4 pts required a total of 5 HOS for clinical instabi- lity; during N, 2 pts required such, whereas no pts re- quired HOS during V.

chest painsfwk HOS/2 months P 15.9f37.2

NTG&wk 18.2-44.0 5

V 2.2*3.2* 3.2+5.3* o* N 1.2*1.5* 2.*4.1* 2 ('pcO.05 when compared to P) V caused mild constipation in 2/10 pts not requiring a change of dosage; in contrast, N induced orthostatic dizziness in 3/10, substantial head- ache in 2/10, and pedal edema in l/10, all necessitating a reduction in dosage. Thus, (1)verapamil and nifedipine demonstrate similar efficacv in the treatment of variant angina, although (2)in this small number of patients. nifedioine was associated with more substantial side effect; than either placebo or verapamil.

398 February 1991 The American Journal of CARDIOLOGY Volume 47