TUESDAY AFTERNOON, MAY 9, 1989

1:45 p.m. SCIENTIFIC SESSION - HYNES BALLROOM

19. Risk Factors for Pulmonary Thromboendarterectomy

PAT O. DAILY, WALTER P. DEMBITSKY*,

STEIN IVERSEN*, KENNETH M. MOSER*

and WILLIAM AUGER*

San Diego, California

Pulmonary thromboendarterectomy is emerging as an effective surgical procedure for incapacitating pulmonary hypertension secondary to chronic pulmonary embolism. However, patient-related risk factors and procedural complications associated with morbidity and mortality have not been described.

Since October 1, 1984, we have performed pulmonary thromboendarterectomy utilizing deep hypothermia and circulatory arrest in 103 consecutive patients (64% male, mean age 50 ± 16 (SD), range 19-81 years) in whom the exposure and dissection of the pulmonary arteries and methods for myocardial protection have been standardized. Ventilator dependency (≥5 days on respirator), the most common and severe postoperative complication, occurred in 27 patients. By univariate analysis, the occurrence of ventilator dependency was associated with long-standing symptoms (p<.01), severe right heart failure (p<.03), severely deranged pulmonary function tests (p<.02), and longer cardiopulmonary bypass times (p<.03). Patients with postoperative neurological disorders (18) were found to have had prolonged total circulatory arrest times (69 ± 21 vs 53 ± 23 min, p<.02).

Hospital mortality was 11.7% (12/103). Causes of death were acute pulmonary hemorrhage or hemorrhagic edema (3), acute myocardial infarction (1), right heart failure (2), and acute respiratory (3) and secondary multi-organ failure (3). Factors associated with mortality were older age (61 ± 14 vs 49 ± 16 years, p<.03), prolonged cardiopulmonary bypass time (215 ± 42 vs 180 ± 47 min, p<.04), intraoperative pulmonary hemorrhage (16.7 vs 0%, p 0.01), and persistent elevated pulmonary vascular resistance (438 ± 141 vs 276 ± 142, p<.005).

Hospital mortality of 11.7% for pulmonary thromboendarterectomy is acceptable when compared to the approximately 25% rate for heart-lung transplantation which is the only therapeutic alternative. Factors associated with ventilator dependency were long standing symptoms, severe right heart failure, severely deranged pulmonary function tests, and longer cardiopulmonary bypass times while predictors of hospital mortality were older age, prolonged cardiopulmonary bypass times, intraoperative pulmonary hemorrhage, and persistent elevated pulmonary vascular resistance.

*By Invitation

20. Rupture of Thoracic Aorta Due to Blunt Trauma: A 15-Year Experience

R ADAMS COWLEY, STEPHEN Z. TURNEY,

JOHN R. HANKINS, AURELIO RODRIGUEZ*,

SAFUH A TTAR and BELAVADI SHANKAR*

Baltimore, Maryland

Repair of rupture of the thoracic aorta from blunt trauma is associated with high mortality and major complications, especially paraplegia/paresis. This is the largest reported series of such cases. During the 15 years from 1971 through 1985, 114 patients with rupture of the thoracic aorta due to blunt trauma were admitted to a major trauma center. Mean age was 31.3 years (range, 15 to 80). Ninety were males and 24 were females, a 3.75:1 ratio. Of the 114, 88 (77.2%) survived initial resuscitation in the admitting area or operating rooms (AA/OR). Twenty-four of the 88 initial survivors (27.3%) died during or following surgical repair. Paraplegia occurred in 11 of the 88 survivors (12.5%).

Further analysis was done of the 83 cases admitted in the 10-year period from 1976 through 1985. Mean Injury Severity Score (ISS), excluding aortic injury, was 18.2. Twenty-six of the 83 (31.3%) died during resuscitation in the AA/OR. Six others died during surgical repair, and 12 died postoperatively leaving 39 survivors (39/83 or 47% of total admissions and 39/57 or 68.4% of survivors of resuscitation). Shunt/bypass adjunct was used to repair 36 injuries and 19 were repaired without adjunct. Paraplegia/paresis developed postoperatively in 10 of 51 survivors (19.6%), with 6 of 34 (17.6%) occurring in cases involving adjunct and 4 of 17 (23.5%) without adjunct (p N.S.). Hypotension during aortic cross-clamping occurred in 3 of 4 paraplegia cases done without adjunct and in 3 of 6 with adjunct (p N.S.). Other major complications occurred in 17 of the operative survivors, including 9 cases of adult respiratory distress syndrome, 3 cases of severe renal failure, 4 cases of severe sepsis, and 3 cases of pseudoaneurysm at graft-aorta anastomoses. Statistically significant risk of death or major complication was associated with higher ISS, larger presenting hemothorax, performance of other major surgery prior to aortic repair, longer aortic cross-clamp time, lower admission blood pressure, and less qualified surgeon.

There was no advantage in this series to using or not using shunt/bypass in preventing paraplegia. Mortality rates are realistic for a highly developed trauma system. Better techniques are needed for management of exsanguina-tion and to prevent paraplegia.

*By Invitation

21. Single Stage Management of Sternal Wound Infection

VALLUVAN JEEVANANDAM*, CRAIG R. SMITH*,

ERIC A. ROSE, JAMES R. MALM, SEAN CAMPBELL*

and NORMAN HUGO*

New York, New York

Median sternotomy wound infection is a significant source of morbidity following cardiac surgery. Accepted approaches in treating this complication include debridement, with either sternal closure over an irrigation system, or open dressings allowing for granulation and secondary closure. Muscle flaps are often used in subsequent procedures. In order to eliminate the need for multiple operations and to decrease hospital stay, a single stage procedure was developed and is compared to previous methods in treating sternal wound infections.

This report is based on a consecutive series of 47 sternal wound infections occurring in 2872 cardiac procedures (incidence 1.7%) over a four year period (1984-1988). The first 16 patients (group A) were treated with closed irrigation drainage (3), or debridement, dressing changes and closure either secondarily (4) or with a muscle flap (9). The subsequent 31 patients (group B) had a single stage procedure. Treatment grouping was not influenced by severity of infection. Immediately after the diagnosis of mediastinitis was made, the wounds were opened widely, necrotic tissue debrided, and sternum resected back to bleeding bone. Full thickness pectoralis major myocutan-eous flaps were created by dividing the muscle at the sternal insertion and elevating the flap off the anterior chest wall. The myocutaneous flaps were mobilized to close the sternal defect primarily. Closed-suction drains were placed under the flaps and were left in place for an average of 7 days. Other than suction drainage, no further attempt was made to obliterate dead space.

All patients had mediastinitis and sternal instability. 4 group A patients and 8 group B patients had osteomyelitis of the sternum. The causative organisms were similar in both groups: Staphylococcus epidermidis (Group A, n = 9, Group B, n = 14), Staphylococcus aureus (Group A, n = 3, Group B, n = 7), beta hemolytic Streptococcus (Group A, n=0, Group B, n = 3), gram negative organisms (Group A, n =4, Group B, n = 7). Antibiotics were directed by culture and sensitivity, and administered from 5 to 45 days (average 12 days). After operative treatment of mediastinitis, group B patients had a shorter mean hospital stay (20 vs 42 days, p<0.05) and fewer reoperations (4/31 vs. 13/16, p<0.05). Infection did not recur in any group B patient at a mean follow-up of 24.5 months (3 - 48 months). Mortality rates were not statistically different (Group A 6.2%, Group B 12.5%). Deaths were all due to cardiac or pulmonary dysfunction, not infection.

Single stage treatment consisting of debridement, immediate mobilization of bilateral pectoral myocutaneous flaps, and primary closure significantly reduces the morbidity caused by sternal wound infections, and should be adopted as the treatment of choice for this complication.

2:45 p.m. Intermission - Visit Exhibits

*By Invitation

3:30 p.m. SCIENTIFIC SESSION - HYNES BALLROOM

22. Surgical Management of Wolff-Parkinson-White Syndrome in Infants and Small Children

FREDA. CRAWFORD, JR., PAUL C. GILLETTE*,

MARTHA R. STROUD* and VICKI ZIEGLER*

Charleston, South Carolina

Surgical ablation of accessory conduction pathways (ACP) has rarely been reported in infants and small children with Wolff-Parkinson-White Syndrome. In the interval January 1985 to September 1988, 19 infants and children age 5 or less have undergone surgical ablation of ACP because of recurrent supraventricular tachycardia (SVT). There were 12 (63%) males and 7 (37%) females. Age ranged from 4 to 66 months (mean 33.8 months). Nine infants were less than 24 months old. Weight ranged from 5.5 to 21.6 kg (mean 13.2 kg). All 19 patients were symptomatic with duration of symptoms ranging from 3 to 63 months (mean 21 months). ACP were classified preoperatively as left free wall in 4 (21%), right free wall in 9 (47%) and posterior septal in 6 (32%). No patient was recognized preoperatively to have multiple pathways. Left ventricular function was abnormal in 4 (21%) preoperatively. Free wall pathways (13) were surgically dissected and septal pathways (6) were cryoablated at -70°C. Mean cardiopulmonary bypass time was 60 ± 4 minutes. Mean cross-clamp time was 42 ± 2 minutes in those undergoing surgical dissection. Mean postoperative stay was 6.4 ± 0.2 days. There were no deaths, no significant postoperative complications, no incidence of complete heart block, and all patients were considered cured at the time of discharge. At a mean follow-up of 12.7 months, 18 (94.7%) remain cured. One patient with Ebstein's anomaly and a right freewall pathway developed a recurrent SVT 3 months postoperatively and repeat electro-physiologic study has shown a previously unsuspected anterior septal pathway. Ventricular function returned to normal in all 4 patients who had abnormal function preoperatively. Surgical ablation of accessory conduction pathways can be safely carried out in infants and small children with results equal to those obtained in adults.

*By Invitation

23. Peri-Nodal Cryosurgery for AV Node Reentry Tachycardia

JAMES L. COX, T. BRUCE FERGUSON, JR.*,

BRUCE D. LINDSAY*, DENNIS M. CASSIDY* and

MICHAEL E. CAIN*

St. Louis, Missouri

AV node reentry tachycardia is the most common cause of paroxysmal atrial tachycardia (PAT). Available non-pharmacologic therapies include: 1) catheter ablation or cryosurgical ablation of the His bundle and insertion of a permanent pacemaker, 2) surgical dissection around the AV node or discrete cryosurgery of the peri-AV nodal tissues in an attempt to divide or ablate only one of the dual AV node conduction pathways responsible for the tachycardia while leaving the other intact. This report describes 20 consecutive patients with AV node reentry tachycardia who underwent the discrete cryosurgical procedure between August 13, 1982 and October 10, 1988. The first patient in this series, a 38 year-old female, represents the first surgical cure of a patient with refractory AV node reentry tachycardia by a procedure designed to treat this arrhythmia. The 11 female and 9 male patients ranged in age from 12-56 years with an average age of 29 years. Eleven of the 20 patients (55%) had the WPW syndrome. Other associated arrhythmias included atrial flutter/fibrillation (1), right atrial reentrant tachycardia (1), junctional tachycardia (1), and a Mahaim fiber (1). Associated anatomic abnormalities included Ebstein's Anomaly in 2 patients and a large right atrial aneurysm in 1 patient. The discrete cryosurgical procedure was performed through a right atriotomy in the normothermic beating heart. Multiple 3mm diameter cryolesions were placed around the borders of the Triangle of Koch on the lower right atrial septum to alter the input pathways of the AV node.

There were no operative deaths in this series of patients. Postoperatively, all 20 patients have normal A-V conduction and no heart block has occurred in any patients during the follow-up period. All patients have remained free of AV node reentry tachycardia (and of the WPW syndrome) and none have required postoperative anti-arrhythmic drugs for either of these arrhythmias. We consider this simple, safe, easily performed and uniformly successful operation to be the procedure of choice for the treatment of medically refractory AV node reentry tachycardia.

*By Invitation

24. Transatrial Balloon Technique for Activation Mapping During Surgery for Recurrent Ventricular Tachycardia

LYNDA L. MICKLEBOROUGH*, EUGENE DOWNAR*,

AKIHIKO USUI*, LOUISE HARRIS*, IAN PARSONS*

and GORDON GRAY*

Toronto, Ontario, Canada

Sponsored by: Tirone E. David, Toronto, Ontario, Canada

Results of surgery for recurrent ventricular tachycardia have improved since methods of mapping have been developed which allow a directed approach to the problem. Using standard operative techniques (ventriculotomy and introduction of a hand-held probe or multiple electrode array), it has not always been possible to obtain satisfactory endocardial activation maps during the tachycardia. We have recently developed a new transatrial balloon approach which has greatly facilitated intraoperative mapping in these patients. A videotape will be presented which demonstrates this technique with particular attention given to the following:

1) description of the balloon array of 112 silver bead electrodes

2) technique for pressure-volume calibration of the balloon

3) technique of cardiopulmonary bypass and surgical approach for balloon insertion across the mitral valve

4) recording of local electrograms and on-line video display of the activation sequence used for intraoperative identification of the "target area"

5) correlation between position of target electrodes on the balloon and the internal geometry of the heart

6) choice and application of the appropriate ablation technique.

We have used this technique in 34 consecutive patients referred for surgical control of ventricular arrhythmias, 35% of whom had only nonsustained ventricular tachycardia at their preop electrophysiologic study. Thirty-eight percent of these patients had a grade IV ventricle, 32% had a previous posterior infarct, and 50% did not have a resectable aneurysm. All of these factors have been associated with poor operative results in other series. With the transatrial balloon technique we were able to induce and map ventricular tachycardia in 100% of patients (average 2.5 ± 1.3 morphologies per patient). Using a variety of ablation techniques (endocardial excision, cryoablation or balloon electric shock ablation) we have achieved surgical control of the arrhythmia in 80% of patients with an operative mortality of 15%. We recommend transatrial balloon mapping as the procedure of choice for intraoperative identification of arrhythmogenic foci in patients with recurrent ventricular tachycardia.

*By Invitation

25. Transannular Mapping and Cryoablation: A New Surgical Approach for Cure of Ventricular Tachycardia

GERALD M. LAWRIE, ANTONIO PACIFICO* and

RAJ R. KAUSHIK*

Houston, Texas

Patients who require electrophysiological map-guided direct surgical procedure usually have depressed left ventricular function. In our own experience in 82 patients, the mean preoperative EF was 36%, range 11-61%. Operative mortality in most series has been in the range of 10-15% and in ours was 12.2%. Patients with no discrete left ventricular aneurysm who have diffuse ventricular impairment are at special risk.

In order to attempt to reduce this risk, we have begun to employ transan-nular cryoablation of arrhythmogenic areas without ventriculotomy or ventricular resection.

A balloon electrode array carrying 80 bipolar electrode pairs is employed for endocardial mapping through either the mitral or tricuspid annulus. Cryoablation has then been performed via the mitral annulus in two patients, the tricuspid annulus in two patients, and the aortic annulus in one patient.

There were three males and two females. Coronary disease was present in three patients and idiopathic cardiomyopathy in two patients. Mapping and cryoablation were uneventful. All patients survived operation. Ventricular tachycardia was non-inducible at post-operative electrophysiologic study in all patients and the ejection fractions were unchanged.

In conclusion, in patients who do not require resection of ventricular aneurysms for hemodynamic reasons, transannular mapping and cryoablation without ventriculotomy is our procedure of choice.

4:50 p.m. EXECUTIVE SESSION (Members Only)

7:00 p.m. PRESIDENT'S RECEPTION (Tickets Required) REPUBLIC BALLROOM, SHERATON

*By Invitation