MONDAY AFTERNOON, APRIL 22, 1968

2:00 P.M. Scientific Session: REGULAR PROGRAM

Ballrooms 1 and 2

8. Ventriculomyotomy in Hypertrophies of the Left Ventricle

J. P. Binet,* J. Langlois,* A. Leiva-Semper,* and Ph. David,*

Paris, France

Sponsored by W. G. Bigelow

The beneficial effects of Ventriculomyotomy in abolishing obstruction in muscular subaortic stenosis are now well documented. In a number of patients with valvular stenosis, severe secondary muscular hypertrophy is known to maintain obstruction following surgical relief of the stenosis. In two patients following insertion of a Starr valve for aortic valvular disease there was persisting left ventricular outflow obstruction with a low output syndrome. This was relieved in each case by Ventriculomyotomy. This has stimulated us to study the further use and a modification of the Ventriculomyotomy operation. Thirty-three patients with primary (16) and secondary (17) muscular hypertrophy were treated by Ventriculomyotomy. In six cases with pure muscular subaortic stenosis, the localized Ventriculomyotomy described by Bigelow was utilized. In the remaining 27 cases (10 with muscular subaortic stenosis, 17 with secondary hypertrophy) the technique was modified to include the entire length of the anterior wall of the left ventricle, from the base of the aortic valve to the apex of the heart. A combined ventriculo-aortic approach was used. Precise anatomic measurements, adequate lighting and special instrumentation are necessary. The post-operative electrocardiogram has not revealed significantly altered ventricular conduction. In summary, (a) the extension of the use of Ventriculomyotomy is recommended, (b) Evidence is presented which indicates that there is a place for a modified or "extended Ventriculomyotomy" in some cases of left ventricular outflow obstruction.

9. The Selection of Patients for Resection of Left Ventricular Aneurysm

James A. Key, Harold E. Aldridge,* and D.C. MacGregor,*

Toronto, Ontario

Review of the clinical and catheter findings in 35 adult patients with left ventricular aneurysm suggests that the best results of treatment can be achieved by proper selection and classification of the different types of lesion encountered. Patients fell into two groups - those operated upon (13 cases) and those in which operation was considered inadvisable (22 cases). In the surgical group a correct pre-operative selection was made in 10 of the 13 patients and a good clinical result was obtained with no hospital mortality. Of the 3 remaining patients the aneurysm was considered unresectable in 2 cases and attempted resection failed in the third. In the non-surgical group (22 cases) the reasons for advising against operation will be discussed. We hope that this review will, on the one hand, confirm the great benefits to be achieved and the minimal operative risk involved in resection of left ventricular aneurysms in properly selected cases, and on the other hand, will help to safeguard the merits of the operation by emphasizing the pitfalls of surgery where unwise pre-operative selection has been made.

10. Support of Myocardial Performance After Open Cardiac Operations by Rate Augmentation

Robert S. Litwak, Leslie kuhn,* Howard L. Gadboys,

Salvador B. Lukban,* and Hideki Sakurai,* New York, N.Y.

After intracardiac operations certain patients exhibit low cardiac output (CO) associated with bradycardia and impaired myocardial contractility. During the past two years 29 postperfusion patients with slow nodal rhythm or atrial fibrillation have had their ventricular rates electrically maintained between 85-115 beats/min. with epicardial wires implanted at operation (Starr) with measurable improvement of CO. Postoperative hemodynamic measurements were performed in 15 patients who were otherwise stable in the sequence: (a) pacing (85-95 beats/min.), (b) non-pacing, (c) pacing (95-115 beats/min.). Non-pacing (b) was associated with a fall in CO averaging 22.8%. Resumption of pacing at a higher rate (c) resulted in a CO rise which exceeded initial measurements (av. 32%). Thus, within the pacing range, CO varied directly with rate. Pacing was also associated with small but consistent reduction of L and R atrial pressures, LV stroke work and systemic vascular resistance. In three paced subjects isoproterenol (1 ug/min.) resulted in further rise in CO with no rate change. Relatively low ventricular rates contribute to reduced cardiac output after intracardiac surgery and pacing exerts a significant salutary effect. Prophylactic implantation of myocardial wires for rate control is suggested for all severely incapacitated patients undergoing cardiac operations.

11. Profound Hypothermia in Cardiac Surgery

R. H. R. Belsey, K. Dowlatshahi,* G. Keen,* Bristol, England,

and David B. Skinner,* Baltimore, Md.

In Bristol, England, from 1961 to July 1967, 304 consecutive open-heart operations were performed employing complete circulatory arrest for up to 120 minutes at temperatures between 10-20°C. This experience includes a full range of congenital (205 cases) and acquired (99) heart diseases. Preoperative status, temperatures, flow rates, and pressures during cooling and wanning, duration of arrest, operative procedures, postoperative assessment of cardiac, renal, pulmonary, hepatic, neurological, and hematologic function, results, complications, and deaths have been analyzed and will be presented to show the effects of profound hypothermia in humans in relation to the technical problems and underlying diseases encountered. Specific complication rates, including neurological, appeared no higher than expected following total cardio-pulmonary bypass at normal temperatures. Continuous EEG monitoring and maintenance of end-tidal CO₂concentrations at 4.5% have been valuable to avoid neurological abnormalities and acidosis. Serial monitoring of serum electrolytes during cooling and warming in 98 patients identified potassium shifts requiring adjustment. Modifications in the original Drew technique facilitated cooling of patients with pulmonary hypertension. These studies demonstrate that profound hypothermia is associated with acceptable mortality and morbidity, and offers specific advantages and disadvantages which will be described.

12. Clinical Experiences with Computerized Monitoring of Cardiovascular Variables in the Postoperative Thoracic and Cardiovascular Patient

JD Mortensen, and Lynn H. Anderson,* Salt Lake City, Utah

Continuous computerized monitoring of central aortic blood pressure, pulse contour, cardiac output, stroke volume, peripheral vascular resistance, and mechanical duration of systole has been used on more than 120 selected patients in our hospital during the past year. This paper presents the findings resulting from review of these patients in whom this sophisticated new clinical tool has been used. We have found this technique to represent a significant advance in the care of postoperative cardiovascular patients. It is particularly useful in the high risk patient in whom a difficult or stormy postoperative course is anticipated. In addition, this system of monitoring can effectively detect subtle changes in cardiovascular status before these can be recognized by the usual clinical means, thus avoiding the later development of more difficult problems. We have not experienced significant complications from this method of physiologic monitoring. Details of the technique and type of data obtained from this new clinical test will be illustrated.

13. The Importance of Serial Blood Gas Determinations in Blunt Chest Trauma

A. J. Wise,* C. Topuzlu,* H. G. Page,* and E. L. Mills,*

Burlington, Vt.

Sponsored by Emil Blair

Serious and potentially lethal pathophysiologic changes often are not detectable in the vital early periods of blunt chest trauma, before "flail" and/or lung contusion become apparent. In a consecutive series of 100 patients seen in the Emergency Room over a 2½ year period, 20 demonstrated a low arterial pO₂ upon admission. At this point, there was no clinical nor radiologic evidence of hypoxia, except for rib fractures with hemo-pneumothorax in a few. In the majority, evidence of pulmonary contusion appeared later. Nasotracheal intubation with IPPB was instituted promptly, while otherwise this would have been delayed. Most of these patients subsequently developed severe pulmonary complications. In another 50 patients the injuries were so severe that intubation and IPPB were carried out immediately, before blood gas determinations could be obtained. Management included serial, frequent blood gases with adjustments in oxygen concentration and dead space to maintain blood gases within normal limits. The mortality rate was 5%from thoracic injuries alone and another 1% from associated injuries and their complications. There was not one single instance of cardiac arrest due to hypoxia in either group. Representative cases demonstrating the accuracy of serial arterial gas determinations in the assessment of early hypoxia will be presented.

14. Penetrating Wounds of the Heart: An Analysis of Over 320 Cases

W. L. Sugg,* William J. Rea,* Watts R. Webb, Earl Rose,* and

R. R. Shaw, Dallas, Texas

In eight years over 320 penetrating heart wounds were admitted to Parkland Memorial Hospital. Approximately 70% were dead on arrival, principally from ventricular wounds. Gunshot wounds were more deadly than stab wounds. In earlier years treatment consisted of pericardiocentesis with surgery only for progressive deterioration, which proved unsatisfactory. Under a new policy started during 1965, all patients are taken immediately to the OR, though some have required pericardio-centesis or even thoracotomy in the Emergency Room. All gunshot wounds are treated operatively as are all but minimal stab wounds. The rare patient treated only by aspiration is observed until recurrent tamponade appears unlikely. A second thoracentesis is always an indication for operation. In the past two years of 35 patients admitted with signs of life, only two died (lacerated coronary artery and massive air embolism). Complications of operative and nonoperative treatment will be presented. On the basis of these results we recommend immediate thoracotomy for all gunshot wounds and most stab wounds of the heart, utilizing pericardiocentesis as a diagnostic or life-saving therapeutic measure prior to surgery.

*By Invitation