ABSTRACTS

LONG-TERM DURABILITY OF PATENT SAI'NENOUS VEIN AORTO- CORONARY BYPASS GRAFTS. Samuel B. Itscoitz, MD; David R. Redwood, ND; Leonard E. Grauer, MD; Robert L. Reis, MD; Edward B. Stinson, MD; and Stephen E. Epstein, MD, NHLI, Bethesda, Md.

The ultimate role of saphenous vein bypass operation (SVBO) in the treatment of coronary artery disease (CAD) depends largely on whether grafts tend to occlude with time. To answer this question we restudied 17 patients (aged 36 to 62 years; avg, 49) who underwent SVBO for chronic severe angina pectoris. Patients were selected if they had patent grafts demonstrated at early postoperative study (3 to 9 mos postoperatively). One additional patient (25 years of age) was studied who had SVBO 6 years pre- viously for anomalous origin of the left coronary artery. The 17 CAD patients had a total of 26 grafts patent at early postoperative study: 18 grafts were widely patent with good distal run-off, 5 were widely patent with slow distal run-off, 2 had stenoses at the coronary anastomo- sis (one mild, one severe with poor run-off), and one had minor luminal irregularities. Late postoperative study was performed 15 to 36 mos (avg 21 mos) following SVBO for CAD. Twenty-four of the 26 grafts were unchanged. One patent graft with good run-off developed minor luminal irregularities; the graft with severe stenosis at the coronary anastomosis had occluded. In the patient with anomalous left coronary artery, a widely patent graft with good run-off was found 4 months postoperatively. Re- study 4.5 years later revealed no change in the appear- ance of the graft. These results suggest that vein grafts, which within 3 to 9 months following SVBO are widely patent and have good run-off, are anatomically and functionally stable during the ensuing one to 4 years. Their history subsequent to this awaits further definition.

CORONARY HEMODYNAMICS, AND MYOCARDIAL PERFUSION AFTER REESTABLISHINC CORONARY FLOW IN EXPERI?IENTAL MYOCARDIAL INFARCTION Jay M.!l. Jarmakani, M.D., Jimmy L. Cox, M.D., Thomas C. Graham, D.V.M., and Donald B. Hackel, M.D., Duke Univer- sity Medical Center, N.Carolina, UCLA Medical Center, Ca.

To determine the effect of varying periods of ischemia on coronary hemodynamics and regional myocardial flow. both phasic left circumflex coronary artery (LCCA) flow and regional myocardial flow using the radioactive micro- sphere (S-lop) method were utilized in 3 groups of chron- ically prepared awake dogs: I, 60 minutes occlusion of the LCCA (n-6); II, 3 hours occlusion of LCCA (n=13): and III, 24 hours occlusion of LCCA (n+). The aortic pres- sure, phasic LCCA flow and the electrocardiogram were monitored continuously before, during and after LCCA oc- clusion. Inner and outer regional myocardial flow were determined before (control) and during occlusion, 15 min- utes after reestablishing LCCA flow, and 26 hours after occlusion. LCCA flow after releasing the snare was sig- nificantly increased in all dogs. Both coronary flow and hyperemic response to 20 second LCCA snare returned to normal in 30-60 minutes. During occlusion, the flow in the infarcted region was higher (p<.OOl) in the epicardi- al region (33+3% of control) than in the endocardial re- gion (9+2%). -15 minutes after reestablishing flow. the infarcted region flow was significantly (p<.Ol) higher than control in groups I, II, but was significantly (p(.OOl) reduced in group III (22+15%). In group II the endocardial flow after releasing The snare decreased sig- nificantly (pC.01) from 137+6% to 37+8% 23 hours later and was not different from &docardial flow in group III. These data indicate that the histological changes pro- duced by 3 hours of myocardial ischemia severely limits future myocardial perfusion, even if flow is reestab- lished after the initial ischemic period.

DETECTION OF MITRAL REGURGITATION BY DOPPLER ECHOCARDIOGRAPHY Steve L. Johnson, MD; Donald W. Baker, BSEE; Robert A. Lute, BS; John A: Murray, MD, FACC, University of Washington, Seattle, Wash.

A range-gated pulsed Doppler flowmeter, with a 2x4 mm teardrop-shaped sample volume, was used to detect the presence or absence of mitral regurgitation (MR) in 58 sequential patients that underwent left heart catheteriz- ation and angiocardiography. Using the A-Mode display, the sample volume was positioned within the left atrium (LA), and at least 3 separate flow readings were obtained before MR was excluded. In MR there is a harsh systolic jet that sounds like steam escaping from a high-pressure pipe. TWO of the 58 patients were excluded due to very poor ultrasound penetration, and 4 were excluded due to uncertainty concerning their catheterization results. In the remaining 52 patients, there was a negative Doppler study in 24, which consisted of 20 with no MR at catheter- ization and 4 false negatives, 3 of whom had minimal to mild MR and one with moderate MR. The other 28 patients had a positive Doppler test, and at catheterization 26 had clearcut MR and 2 had MR only with premature ventricular contractions. These latter 2 patients may be either false positives or may indicate that the Doppler test is very sensitive. This techniaue provides an indirect method for localizinq the origin of cardiac murmurs, and in some patients makes further diagnostic studies unnecessary.

DOES RESTORATION OF BLOOD FLOW PRESERVE ACUTELY ISCHEMIC MYOCARDIUM? James Kane, MD; Marvin Murphy, MD, FACC; Joe Bissett, MD; James Doherty, MD, FACC; Karl Straub, MD. VA Hospital & Univ of Ark Med Center, Little Rock, AR.

Surgical intervention with bypass grafts has been ad- vocated as treatment for acutely ischemic myocardium. The purpose of this study was to determine the length of time myocardium remains viable as measured by mitochon- drial function after acute coronary occlusion and whether restoration of blood flow would salvage ischemic muscle. The left anterior descending coronary artery was occluded at its midportion in 27 pigs and then released at inter- vals varying from 15 minutes to 3 hours. One group of animals had a permanent ligation, The ischemic zone and blood flow were estimated by gross inspection, epicardial EC&, vital dye stain, distribution of 3H digoxin, and flow probe studies. Two hours after ligature release the beating heart was removed and a mitochondrial pellet pre- pared from ischemic and non-ischemic LV. Oxygen consump- tion, respiratory control ratio (RCR), and ADPjO were measured with malate and glutamate substrates. Results for ischemic tissue are expressed as a percentage of the control (glutamate): LIGATION TIME-min 02 CONSUMPTION RCR ADP/O

15-30 68.4t11.6 97.9f 7.9 95.5t 3.0 60 29.4t19.6 62.6t16.8 92.2t13.0 120 25.6t 8.4 47.8r11.8 96.2?: 9.6 180 9.6? 4.1 43.8i30.5 94.2t22.3 180-no release 19.4? 2.0 17.3? 4.2 72.3?: 5.3 The results show marked impairment of mitochondrial

function in the ischemic zone. The defect appears to be a block in electron transport (state 3 respiration) rath- er than uncoupling of oxidative phosphorylation and was not reversed by restoration of blood flow. The results suggest that irreversible myocardial damage occurs during the first l-3 hours of coronary occlusion.

146 January 1974 The American Journal of CARDIOLOGY Volume 33