Back to Annual Meeting Program
2:00 P.M ScientificSession
Ballroom
37. Four hundred Consecutive Patients withPermanent Transvenous Pacemakers
EDWARD F. CONKLIN,* STANLEY GIANNELLI,JR., and
THOMAS F. NEALON, JR., New York, N.Y.
400consecutive patients were treated with permanent transvenous pacemakers betweenApril 1, 1965 and May 1, 1973 at the St. Vincent's Hospital and Medical Center,New York, N.Y. The average age of the patients was 75 years. All procedureswere performed in the cardiac catheterization laboratory under localanesthesia. Ventricular triggered demand pacemakers were used in 331 patients.There was one operative death. One primary implantation became infected. Threepatients were converted to epicardial pacing following failure of transvenouspacing. This has not been necessary in any of the 350 patients treated sinceOctober, 1967. 156 patients have had a total of 235 pulse generatorreplacements without morbidity. Electrode fracture (10 patients), shift incatheter position (18 patients) and exit block (22 patients) have been easilycorrected without morbidity under local anesthesia. 104 patients died within 22months of implantation. 86 patients have been followed for 40 months or longer,and 10 patients for 80 or more months. Stable catheter position once achievedappears permanent. In the absence of exit block pacing thresholds have shown notendency to rise. No recurrence of Adams-Stokes attacks have been noted in anypaced patient.
The transvenous technique of permanentpacing remains the method of choice because it iseasily tolerated bythese aged patients, the pacing thus achieved is stable and effective, and thefew complications are easily corrected.
38. The Advantages of Transthoracic (TT) ElectrodeImplantation For Permanent Cardiac Pacing
GEDDES (FRANK) O. TYERS,* H. C. HUGHES,JR.,*
H. A. TORMAN,* and J. A. WALDHAUSEN,Hershey, Pa.
It isgenerally accepted that transvenous (TV) electrodes have a lower stimulationthreshold and risk than TT electrodes. The recent literature and our experiencewith >100 pacer insertions indicate a mortality rate of <2% with eithertechnique. As complication rate (2-3x) and the late mortality rate are higherwith TV pacing, and new techniques allow TT electrode insertion under local anesthesia,reinvestigation of pacing thresholds was indicated.
Identical high current density, ball-tipleads (Cordis) were placed intramyocardially on the left (LVA) and right (RVA)ventricular apices and TV in 20 dogs with complete heart block. At 7 stimulusdurations 0.05-5 msec, threshold voltage and current were measured directlyusing an oscilloscope and current probe.
At allstimulus durations in the clinical range, LVA stimulation required less current(all p <0.05), voltage (all p <0.025) and energy (all p < 0.01) thaneither RV site. Threshold energy needs with a 1 msec pulse were: LVA 0.07 �0.01� joules vs RVA 0.18 � 0.05� Joules vs TV 0.15 � 0.02� joules.
There is a 50% reduction in energy needsand battery drain with TT LVA pacing. Previous studies showing TV thresholdslower than TT thresholds used electrodes of differing configuration, surfacearea, and materials which biased results in favor of the endocardial site. Whenall clinical and electrophysiological factors are considered, TT pacing electrodesdeserve much wider clinical application.
39. Surgical Aspects of Regional Myocardial BloodFlow and Myocardial Pressure
RONALD J. BA1RD, MASAO OKUMORI,*FRIEDRICH DUTKA,*
ALBERTO de la ROCHA,* and MARTINGOLDBACH,*
Toronto, Ontario, Canada
Thesurgical manipulations of partial bypass, complete bypass, and ventricularfibrillation have profound effects on regional myocardial pressure and coronaryflow distribution. In 80 experiments on mongrel dogs, regional myocardialpressure was monitored by both the "flow cessation" technique and by"micro-tip" pressure transducers. Regional flow distribution was mapped byradioactive micro-spheres of 15 micron size labelled with three differentisotopes.
The gradient in systolic pressure, from alow subepicardial to a high subendocardial value, persists as the leftventricular volume decreases from normal to partial to complete bypass. Thispressure gradient also persists in the fibrillating ventricle. Neither theregional myocardial pressure nor the regional myocardial flow are affected bythe technique of inducing or maintaining fibrillation (spontaneous, alternatingcurrent, direct current).
If mean coronary perfusion pressure isheld constant, there is an increase in total coronary flow with thechange from normal (82 � 13 S.D. ml./100 Gm of left ventricle/min), to completebypass with the heart beating (117 � 36 S.D.), and a further increase withfibrillation (171 � 34 S.D.). P <.005. Flow to the inner half of theventricle is not a hazard as long as perfusion pressure is adequate.
If perfusion pressure is allowed to fallbelow a critical level (55 - 60 mm.Hg) there is a marked decrease in the innerwall - outer wall flow ratio in the fibrillating heart, suggestinginadequate subendocardial perfusion. This level of critical perfusion pressureis elevated by coronary artery narrowing or ventricular hypertrophy.
40. A Clinical Methodfor Detecting Subendocardial Ischemia Following Cardiopulmonary Bypass
PETER A. PHILIPS,* ALAN T. MARTY,* and
ALFONSO M. MIYAMOTO,* Duarte, Calif.
Sponsored by Lyman A. Brewer, HI, LosAngeles, Calif.
Unrecognized subendocardial ischemia, afrequent cause of death following cardiac surgery, may be present despitesatisfactory systemic and central venous pressures. A more accurate earlyindicator of subendocardial ischemia has been studied experimentally using themyocardial supply/demand ratio (MSDR), defined as the ratio of aortic diastolicpressure time index divided by aortic tension index. To make monitoring of MSDRclinically applicable, an inexpensive electronic circuit was designed utilizingmean left atrial (LA) and radial pressures to determine MSDR. Radial and aorticpressure calculations give similar MSDR values. The figure obtained is termedthe endocardia! viability ratio (EVR).
In 50consecutive open cardiac procedures, EVR, LA, right atrial (RA), and radialartery pressures were recorded intra-operatively and for three dayspost-operatively. Results confirmed the applicability and reliability of EVR asan indicator of myocardial ischemia and patient survival. Forty patients withpost-perfusion EVR's of .9 or greater had uneventful postoperative recoveries.Six patients with acceptable systemic pressures averaging 90/65 mm Hg, hadaverage EVR's of .736 with average LA pressures of 30.3 mm Hg. Immediateapplication of intra-aortic balloon counterpulsation (IABC) resulted in a riseof EVR to 1.26 (p <.01), a fall in LA pressures to 17.9 mm Hg (p <.05),and improvement in electrical and cardiac activity. All six survived. In fourothers, despite IABC, MVR's remained below .6 and all died (two from extensivemyocardial necrosis, two from predominant right heart failure).
Inconclusion, monitoring EVR is clinically useful in detecting early evidence ofsubendocardial ischemia. EVR may fall before systemic or central venouspressure deteriorates, indicating the need for early myocardial support,undetect-able by conventional methods. Furthermore, EVR can easily be adaptedto monitoring equipment currently used in coronary and postsurgical intensivecare units.
41. Selection of the Candidate for MyocardialRevascularization: A Profile of High Risk Based on Multivariate Analysis
FLOYD D. LOOP,* JULIO N. BERRETTONl,*AUGUSTO D.
PICHARD,* WAYNE SIEGEL,* MEHDI RAZAVI,*and
DONALD B. EFFLER, Cleveland, Ohio
Asurvey of 50 patients who died from cardiac related causes after directcoronary artery surgery (1967-1973) was made with respect to 29 clinical,angiographic, and operative variables. These factors were compared withidentical characteristics of 1,283 survivors operated on in 1972. Throughdiscriminant analysis, the various characteristics, isolated or multiple in anycombination, have been converted to risk related to operative death.
The distinctive features of the mortalitygroup were vastly different from those in the surviving group. For example, 24%of the mortality group had probability (risk) indexes of 0.90 or higher,whereas these factors or variables of similar weight produced an equivalentrisk in only 0.8% of the survivors; thus, operative death, under these specificcircumstances, could be predicted with an estimated 96.7% assurance. Each ofsix patients with mortality risks in the 99th percentile had (1) cardiomegaly,(2) ECG evidence of previous infarction, (3) documented congestive heartfailure (CHF), (4) triple vessel coronary artery disease, and (5) elevated leftventricular end diastolic pressure. Other prominent findings in high risksituations included left main or high anterior descending coronary artery obstructionassociated with preoperative signs of cardiac decompensation. As a singlefactor, CHF exerted the most influence on the probability of dying.
A newand more descriptive statistical interpretation of the factors presumed toaffect risk is presented. A numerical index indicates the relative importanceof each variable and yields a coefficient used to predict high and low risksituations from given clinical and arteriographic combinations.
42. Myocardial Revascularization with PoorVentricular Function
BEN F. MITCHEL, JR., Dallas, Texas, PETERALIVIZATOS,*
Athens, Greece, MAURICE ADAM, GARY J.LAMBERT, and
GERALD F. GEISLER,* Dallas, Texas
In order to evaluate current opinionconcerning the inadvisability of bypass surgery for angina patients with poorventricular function and/or congestive heart failure, we have reviewed ourfirst 1000 patients undergoing revascularization. Eighty patients with poorventricular function, as judged by ventriculography and ejection fractiondeterminations, were available for review.
Nine patients were categorized as having"very poor ventricular function" (poor contractility with ejection fraction ofless than 0.2). All nine patients had three vessel disease and all threevessels were bypassed in each instance. Eight patients are alive and well.There were no early deaths and only one late death is noted. (Total mortality:11.1%).
Thirty-one patients were categorized ashaving "poor ventricular function" (poor contractility with an ejection of 0.2to 0.4). Twenty-five patients had three vessel disease but in only 14 patientswere three vessels grafted. There were eight early deaths (25.8%) and five latedeaths (16.1%). (Total mortality: 42%):
Fortypatients were categorized as having "fair ventricular function" (poor contractilitywith an ejection fraction of 0.4 to 0.6). Thirty-six patients had three vesseldisease but in only of 23 patients were all three vessels bypassed. There werefour early deaths (10%) and four late deaths (10%). (Total: 20%).
Mortality, in patients undergoing directmyocardial revascularization with poor ventricular function, therefore appearsto be directly related to the severity of the disease and to whether or notdiseased vessels can be bypassed. Until we can better distinguish the poorly functioningischemic ventricle from the poorly functioning scarred ventricle, we feel thatpatients in this category should continue to be individually evaluated and notcategorically denied surgery.
43. Direct Selective Myocardial Revascularizationby Internal Mammary Artery to Coronary Vein Anastomosis
SANG B. PARK,* GEORGE J. MAGOVERN, GEORGEA. LIEBLER,*
CHARLES M. DIXON,* FRANK R. BEGG,* and
DON L. FISHER,* Pittsburgh, Pa.
In the past year, we have studiedselective retrograde coronary perfusion in mongrel dogs by anastomosing thedistal internal mammary artery to the anterior descending vein, ligating thevein proximally and simultaneously placing an ameroid constrictor on theanterior descending coronary artery. Out of a group of ten dogs, there were twolong-term survivors with a patent graft and a constricted anterior descendingcoronary artery in whom studies indicated retrograde myocardial perfusion. Wehave subsequently performed three clinical cases associated with right andcircumflex artery bypass grafts. These three patients were studied beforeleaving the hospital and showed patent grafts and coronary sinus oxygensaturations and angiographic data which indicated retrograde myocardialperfusion. Subsequent studies at four months on two of the patients studied todate indicated one graft to be open and one to be closed. This paper willpresent the pre- and the post-operative angiograms and follow-up angiograms aswell as the post-operative isotope myocardial scanning and coronary sinussaturation studies. The early clinical data would indicate that the proceduremay have merit when diffuse disease or total obstruction of the anteriordescending coronary artery precludes direct anastomosis. Experimental resultssuggest that the procedure does not prevent an infarction with acute ligationof the concomitant coronary artery as suggested by Kolff in his work in thecalf.
44. The Rationale for Surgery in PreinfarctionAngina
JACK M. MATLOFF, HECTOR SUSTAITA,* KANUCHATTERJEE,*
H. J. C. SWAN,* Los Angeles, Calif.
Of 100patients with identical criteria for preinfarction angina, 33 have been treatedmedically and 67 surgically. Generally, these two patient populations werequite similar in regard to age, sex, number of prior infarctions and duration ofacute and chronic anginal symptoms. With medical therapy, 13 patients died and20 experienced non-fatal infarctions within two weeks. The surgical patientswere studied and underwent saphenous vein bypasses on an emergent basis.Twenty-three of these patients, classified as complicated, experiencedrepetitive ventricular arrhythmias, congestive heart failure, myocardialinfarction and/or shock prior to their referral for surgery. Two of thesepatients experienced post-operative infarction and died. The remaining 44patients underwent surgery with a single mortality. Two to 37 months aftersurgery, 49 of the operated patients are asymptomatic and 3 who infarcted priorto surgery have mild congestive failure. Six patients have residual angina.This experience supports the concept that preinfarction angina is a malignantsyndrome in which the course can be significantly altered by appropriatesaphenous vein bypass.
THEAMERICAN ASSOCIATION FOR
THORACICSURGERY
FUTUREMEETINGS
1975 April 14-16 Americana Hotel
NewYork, New York
1976 April 23-25 Century Plaza
LosAngeles, California
*By invitation
