American Association for

Thoracic Surgery

59TH ANNUAL MEETING

Scientific Program

MONDAY MORNING, APRIL 30, 1979

8:30 A.M. Business Session (Limited to Members)

Ballroom

8:45 A.M. Scientific Session - Ballroom

1. Angina Postacute Myocardial Infarction: A Definite Surgical Indication

RENE G. FAVALORO, ERNESTO E. WEINSCHELBAUM*

FERNANDO J. BOULLON*, VICTOR M. CARAMUTTI*and

LUIS M. DE LA FUENTE*, Buenos Aires, Argentina

Cine coronary angjography can be performed during the acute and subacute phase of an acute myocardial infarction. A total of 318 patients were studied by selective cine coronary angiography without mortality and within 30 days of the acute episode. In 203 patients angina pectoris was the indication for the cine angiographic study; 60% showed severe segmental obstructions and only 40% demonstrated total occlusion of the artery responsible for the infarction. Six different angiographic patterns to be discussed were individualized. The analysis of the clinical history, electrocardiographic changes and the utilization of postextra-systolic potentiation, vasodilators and radioisotopes allow us to differentiate ischemia and necrosis. By means of a careful screening of the data obtained we can select proper candidates for immediate revascularization.

The operation can be performed with an acceptable operative risk (7% in 79 patients) and can be done during the acute phase of the episode (half of the patients were operated upon within the first two weeks of the myocardial infarction). To evaluate the medical and surgical treatment of patients with angina postacute myocardial infarction a group of patients were followed during 34 months, 20 were assigned to medical therapy though they were ideal candidates for revascularization and 40 underwent surgical treatment. This comparative study showed that patients with surgical treatment had a total mortality (early and late) of 7.5%; conversely, patients under medical treatment had a 40% mortality rate. Seventy-seven percent of the patients operated upon are asymptomatic, on the other hand, only 20% of the patients under medical therapy are asymptomatic. It is important to remark that 66% of the deaths in the medically treated group occurred suddenly.

Angina postacute myocardial infarction should be included as another form of unstable angina. Our belief is that patients should be studied by cine coronary angiography and operations performed when indicated. Further extension of the infarcted area can be prevented. Cine left ventriculograms and ventricular function studies can demonstrate significant improvement of left ventricular contractility. Pre and postoperative evaluation will be shown.

*By invitation

2. Improvement of Left Ventricular Function by Coronary Bypass Surgery

M. LAXMANKAMATH*, CHARLESHELLMAN*,

DONALD H. SCHMIDT*, and W. DUDLEY JOHNSON,

Milwaukee, Wisconsin

There has been considerable controversy regarding the beneficial effects of myocardial revascularization surgery (MRS) on left ventricular function. To assess the effects of MRS on exercise-induced myocardial ischemia, 27 patients (pts) with coronary artery disease (CAD) who had MRS performed were prospectively studied by rest (R) and exercise (E) first-pass nuclear angiography (FPNA). All pts had 30° RAO view R+E FPNA 1 to 3 days pre-MRS and 10 days post-MRS. Mean population age was 52 years; the mean number of grafts placed was 3.2 per pt. In addition, 12 young male volunteers assumed to have normal coronary arteries were tested to R+E FPNA to serve as normal control. In all E FPNA studies, pts had progressive bicycle exercise to symptoms of fatigue, dyspnea, or chest pain. Parameters of ejection fraction (EF), end diastolic volume (EDV), stroke volume (SV), and regional wall motion dysfunction (RWMD) were determined from the FPNA data. Average changes from R to E are shown below:

GROUP	EF(%)	EDV(cc)	SV(cc)	ERWMD
No CAD	.62→74*	108→115	65→88*	0 pts
CAD pre-MRS	.63→44*	109→155*	65→62	20 pts
CAD post-MRS	.65→73	102→105	64→76*	0 pts
*indicates significance with p<105

Results: Pre-MRS; 25/27 pts showed significant decrease in EF with exercise, while all 12 pts without CAD showed significant increase in EF. Following MRS; 25/27 CAD pts had significant increase in their EF with exercise.

In conclusion, MRS in pts with significant CAD can improve myocardial performance during exercise by abolishing evidence of ischemia (decreased EF, increased EDV, and E RWMD) as assessed by FPNA testing. In fact, it is suggested that failure to abolish such an abnormal response by such testing may reflect incomplete revascularization.

*By invitation

3. The Transluminal Dilatation of Coronary Arteries and Partially Obstructed Saphenous Vein Grafts

W. B. FORD, M. H. WHOLEY*, E. A. ZIKRIA*, W. H. MILLER*,

S. R. SAMADANI*, and A. G. KOIMATTUR *, Pittsburgh, Pennsylvania

Since January 1978 we have evaluated 12 patients in whom segmental occlusive disease of the aorto-coronary saphenous vein graft or the native coronary circulation was present. The significantly occluded vessels were restored to relatively normal circulation by means of percutaneous transluminal dilatation in 8 of these patients, with technical failures in 3 patients and the occurrence of a thrombosis during the dilatation procedure in one other.

All dilatation procedures are performed under local anesthesia with an open heart team standing by. In the event of technical failure or incipient thrombosis with developing infarction, the patient is transferred for immediate bypass surgery.

This paper will include detailed technical description of the procedure as well as the catheters we have used. Catheter designs utilized thus far include a series of coaxial dilating catheters as well as the balloon-type catheter.

Details of the clinical and laboratory evaluation of selected cases are described, as well as the clinical results. Follow-up of these patients will continue at least 12 months, and our follow-up findings to date will be reported.

Based on these early results, we have developed categorized guidelines of the indications for percutaneous transluminal dilatation of the coronary arteries and the anastomotic sites of their saphenous vein grafts. Percutaneous transluminal dilatation procedures have been performed successfully for occlusive changes in the iliac and femoral vessels, but the technique has only recently been described for the coronary circulation. Certain inherent complications will be mentioned, but our preliminary experiences are encouraging. Our work with transluminal coronary dilatation is progressing, and it is expected that more experience will be available for presentation at the April meeting.

Slides and a 16 mm. movie depicting the catheters and their use will be included in the presentation.

INTERMISSION - VISIT EXHIBITS

*By invitation

SESSION ON CONTROVERSIES

Internal Mammary Artery versus Saphenous Vein Grafts

4. Isoproterenol Induced Flow Responses in Mammary and Vein Bypass Grafts

DONALD H. SCHMIDT*, FRED BLAU*, CHARLES HELLMAN*

and W. DUDLEY JOHNSON, Milwaukee, Wisconsin

Clarification of the relative flow potentials of direct mammary grafts and aorta-to-coronary artery vein grafts is clearly desirable. For this purpose regional myocardial perfusion (RMP) was measured at rest and following isoproterenol (ISO) infusion (4-8/mg/min) to a mean HR of 119 in 38 patients. After injection of 15mCi 133Xe into the coronary artery (CA) or graft, washout of the 133Xe from the distribution of the artery or graft was measured with a multi-crystal scintillation camera. RMP(ml/100g/min) was calculated using the Kety formula. The double produce (DP) of HR and systolic BP was used as an index of myocardial oxygen demand. A response index (RI) was calculated (RI=10³ XDRMP/DDP) to normalize the data. The following mean results were obtained:

	Normal (7)			Veins (17)			Mammaries (14)
	HR	BP	RMP	HR	BP	RMP	HR	BP	RMP
Rest	74	147	70	78	153	74	88	135	80
ISO	116	149	121	118	150	122	121	137	117
RI	8.3 ± 3.7			10.2 ± 5.6			8.7 ± 3.2

Hence there were no significant differences between the response index of the direct mammary grafts (8.7) or vein grafts (10.2) to an occluded left anterior descending CA, as compared to the normal circulation (7.4). The data indicates that mammary grafts produce the same flow response to the increased demand of ISO as do vein bypasses and the normal circulation. Because of the other advantages of the mammary graft (higher patency and total absence so far of late closure), this refutes the often expressed fear that mammary flow is too low for adequate perfusion.

*By invitation

5. Left Anterior Descending Coronary Artery Bypass Grafts: Saphenous Vein Versus Internal Mammary Artery

DENISH. TYRAS*, HENDRICK B. BARNER,

GEORGE C. KAISER, JOHNE. CODD*, D. GLENNPENNINGTON*,

and VALLEEL. WILLMAN, St. Louis, Missouri

During the interval 1972-1977, of 1521 patients undergoing isolated coronary artery bypass grafting, 1458 received grafts to the left anterior descending (LAD). The internal mammary artery (IMA) was used in 765 patients, reversed saphenous vein (SVG) in 693 patients. Choice of bypass conduit was nonrandom. Clinical follow-up is available in 98% of patients. Angiography has been obtained in 67% of eligible patients at 1 month. 60% at 1 year, 60% at 3 years, and 62% at 5 years.

Results:	IMA		SVG		p-value
Age	52.2 ± 0.3		53.1 ± 0.3		<0.05
Women		17.4%		13.0%	<0.025
No. of grafts/patient		2.5		2.5	N.S.
Left main coronary stenosis ≥50% (LMCA)		9.3%		16.9%	<0.005
Pre -infarction angina (PI A)		10.6%		15.0%	<0.025
Operative mortality		1.4%		1.9%	N.S.
Cumulative 5 year survival		88.6%		89.5%	N.S.
Patency of LAD graft (cumulative):
1 month		97.5%		94.1%	<0.005
1 year		92.8%		87.5%	<0.002
3 years		92.0%		85.5%	<0.0005
5 years		89.9%		82.8%	<0.005
Normal preoperative LV function		49.0%		49.0%	N.S.
Normal postoperative LV function:
operation 72-73		54.0%		46.0%	N.S.
operation 74-77		70.0%		59.0%	<0.05
1 year graft patency: operation 72-73	+ {	87.1%	++ {	822%	N.S.
operation 74-77		94.7%		89.8%	<0.01
+ p<0.0125	++ p<0.04

Although the choice of bypass graft conduit was nonrandom and SVG was used more often in the event of LMCA and PIA, perioperative myocardial infarction (MI) was significantly lower in the IMA group (6.3%) vs. the SVG group (10.6%), even when LMCA and PIA patients were excluded (p<0.005).

These data show higher patency rates, lower perioperative MI occurrence, and better preservation of ventricular function with IMA grafts to the LAD. However, these benefits with IMA over SVG were only obtained after two years of experience (approximately 100 patients), and this apparent "learning period" may be a significant deterrent to use of the IMA as a new approach.

*By invitation

6. Clinical Comparison Between Patients with Saphenous Vein and Internal Mammary Artery as a Coronary Graft

JAMES W. JONES*, JOHN L. OCHSNER, NOEL L. MILLS,

and LARRY HUGHES*, New Orleans, Louisiana

Among the few available reports that compare the effects on surgical success, we found that patients having internal mammary artery (IMA) grafts had superior hospital and extended courses. In recent years, improved technique, better myocardial protection, and more extensive revascularization have led to better patency rate of saphenous vein grafts (SVG). Our previous study was extended to include patients from January, 1971 through May, 1978. Of this group, one thousand, two hundred and thirty-nine (1,239) patients had comparable patterns of bypasses. Seven hundred twenty-six (726) patients had SVG's alone and 513 patients had IMA bypasses exclusively or in combination with SVG bypasses. Follow-up ranged from 7.5 years to 6 months and was complete in 99%. In the total group, 493 (96.1%) patients with IMA grafts are alive and 679 (93.5%) patients with SVG are alive (P=0.00378). Rates of anginal relief were not significantly different (P=0.413339). Distribution of the two groups among 193 other variables was examined. After maldistributed subsets were removed, 415 patients having SVG's and 363 patients with IMA's remained for study. Although overall survival rates were better in the unbiased group having IMA bypasses (97.5% vs. 95.7%), the differences were not significant (P=0.38402). Logrank test analyses were done on all survival data and confirmed these findings.

Conclusion - Using present-day techniques of coronary artery surgery, there is little effect on the clinical outcome, whether the internal mammary or saphenous vein graft is used as a conduit. Consequently, the internal mammary artery is indicated (1) as a conduit to small arteries; (2) as a conduit to arteries supplying limited muscle mass; (3) where a vein is unavailable; and (4) where not competitive with the native circulation or a larger vein graft.

11:15 A .M. Presidential Address

A LETTER TO HELEN John W. Kirklin

*By invitation