AMERICAN ASSOCIATION FOR

THORACIC SURGERY

76TH ANNUAL MEETING

SAN DIEGO CONVENTION CENTER

APRIL 29-MAY 1, 1996

MONDAY MORNING, APRIL 29, 1996

8:30 a.m. BUSINESS SESSION (Limited to Members)

8:45 a.m. SCIENTIFIC SESSION

Room 6, San Diego Convention Center

Moderators: Mortimer J. Buckley, M.D.

James L. Cox, M.D.

1. PAEDIATRIC TRACHEAL HOMOGRAFT TRANSPLANTATION.

Jeffrey P. Jacobs, M.D.*, Martin J. Elliott, M.D., FRCS*and Claus Herberhold, M.D.*

London, United Kingdom and Bonn, Germany

Sponsored by: †Marc R. de Leval, M.D., FRCS,

London, United Kingdom

Discussant: Thomas L. Spray, M.D.

Purpose: Tracheal stenosis is a life-threatening problem in children. Recurrent long segment tracheal stenosis is especially problematic. Tracheal homograft transplantation (THT) represents a new treatment option for this difficult group of patients.

Methods: Cadaveric trachea is harvested, fixed in formalin, washed in methiolate, and stored in acetone. The stenosed tracheal segment is opened to widely patent segments proximally and distally. The anterior cartilage is removed and the posterior trachealis muscle or tracheal wall remains. A temporary silastic intraluminal stent is placed and absorbable sutures secure the homograft. Regular postoperative bronchoscopy clears granulation tissue for several weeks. The stent is removed endoscopically after epithelialization over the homograft.

Twenty-four children (age 5 months to 18 years, mean ± standard error of the mean [SEM] = 8.18 ± 1.21 years) underwent THT. All had severe life-threatening tracheal stenosis and had undergone previous failed reconstructive attempts. Ten lesions were congenital, nine were post-traumatic, and five were secondary to prolonged intubation. Eighteen procedures used neck incisions only. Six children required sternotomy. Cardiopulmonary bypass (CPB) allowed THT for more distal lesions down to and beyond the carina and allowed THT in the small infant. CPB was necessary in five procedures. Three patients without functional airways required stabilization with preoperative extra-corporeal membrane oxygenation.

Results: Follow-up ranged from 5 months to 10 years (mean ± SEM = 3.73 ± 0.71 years). Twenty patients survived (20/24 = 83%), seventeen without any airway problems. Three patients are still undergoing treatment. One patient requiring emergent ECMO support preoperatively expired three weeks postoperatively. Another patient with severe preoperative mediastinal sepsis expired 20 weeks postoperatively. Two patients died with functional airways: one died from unrelated gastrointestinal problems eighteen months postoperatively and one died from cardiac failure.

Conclusions: THT represents a new treatment modality with encouraging short to medium-term results for children with severe recurrent long segment tracheal stenosis. Postoperative bronchoscopic and histologic studies provide evidence of epithelialization and support the expectation of good long-term results.

†1973-74 Graham Fellow

*By invitation

2. LOOKING FOR THE ARTERY OF ADAMKIEWICZ: A CLINICOPHYSIOLOGIC QUEST.

Randall B. Griepp, M.D., M. Arisen Ergin, M.D., Ph.D., Steven L. Lansman, M.D.*, Jan D. Galla, M.D.*, Cid S. Quintana, M.D.* and Jock N. McCullough, M.D.*

New York, New York

Discussant: Joseph S. Coselli, M.D.

In a renewed effort to lower the incidence of postoperative paraplegia, all patients undergoing thoracic or thoracoabdominal aneurysm resection since October 1993 have had spinal cord function monitored with somatosensory evoked potentials (SSEP) intraoperatively, and postoperatively until awakening. In an attempt to identify segmental vessels critical to cord blood supply, each vessel in the segment to be resected was occluded temporarily: if no change in SSEP latency or amplitude occurred within 10-15 minutes, it was ligated and divided. Adjunctive measures to protect spinal cord function included mild generalized hypothermia (31-33°C), distal perfusion (in all but three cases), corticosteroid administration, maintenance of high normal blood pressure perioperatively, avoidance of nitroprusside, and cerebrospinal fluid drainage when multiple pairs of peridiaphragmatic intercostals were sacrificed.

Neurological outcome in 73 consecutive patients so treated (Group II) was compared with a group of 138 consecutive patients operated on earlier who did not have SSEP monitoring (Group I). Preoperative clinical characteristics did not differ significantly between Group I and II patients: average age, 63 vs. 65 years; male, 64 vs. 56%; urgent or emergent operation 41 vs. 51%; dissection, 28 vs. 21%.

The incidence of permanent spinal cord injury was significantly lower in some categories of Group II patients:

Transient evidence of spinal cord ischemia was observed in three patients postoperatively: all had return of function in response to supportive measures to increase spinal cord perfusion, including elevation of blood pressure and spinal fluid drainage.

The reversal of transient spinal cord ischemia as well as the lower incidence of permanent spinal cord injury in Group II patients suggest that careful monitoring of spinal cord function and a multimodal approach to maximizing spinal cord blood flow are effective in preventing paraplegia following thoracoabdominal aneurysm resection. Since intraoperative SSEP was not affected by gradual serial intercostal sacrifice in any patient, the low incidence of spinal cord injury in Group II patients was achieved without reimplantation of a single intercostal or lumbar artery. We conclude that spinal cord blood supply is unlikely to depend upon a single artery, or even a small number of critical segmental vessels, and that spinal cord perfusion can be effectively manipulated using generalized adjunctive measures. We question whether there is indeed an "Artery of Adamkiewicz" of physiologic significance.

*By invitation

3. RESULTS OF LUNG VOLUME REDUCTION SURGERY IN 120 CONSECUTIVE PATIENTS.

Joel D. Cooper, M.D., G. Alexander Patterson, M.D., R. Sudhir Sundaresan, M.D.*, Elbert P. Trulock, M.D.*, Roger D. Yusen, M.D.* and Stephen S. Lefrak, M.D.*

St. Louis, Missouri

Discussant: John R. Benfield, M.D.

Between January 1993 and August 1995, 120 patients have undergone median sternotomy and bilateral lung volume reduction surgery for severe emphysema. Selection criteria include severe dyspnea, thoracic distention, and "target" areas in the lung which can be excised to reduce lung volume without significant sacrifice of functioning lung tissue. All candidates are enrolled in a structured exercise rehabilitation program for a minimum of six to eight weeks before final acceptance.

Early mortality (<90 days) has been 2.5%, all from respiratory complications. Late mortality (>90 days) has been an additional 2.5% (post-coronary bypass at 3 months; unknown causes at 5 months; stroke at 9 months). Mean hospital stay has been 14.5 days and median stay 11 days. Due to modifications in technique and post-operative management, the mean stay has been reduced to 10.5 days and the median stay to 8 days for the last 40 patients.

Follow-up is complete on 119 patients with a mean follow-up time of 358 days and median of 327 days. Results of on-site follow-up studies are as follows:

For selected patients with severe chronic obstructive pulmonary disease, lung volume reduction surgery improves respiratory mechanics, diminishes oxygen requirement, reduces dyspnea and improves the quality of life.

9:45 a.m. INTERMISSION - VISIT EXHIBITS

*By invitation

10:30 a.m. SCIENTIFIC SESSION

Room 6, San Diego Convention Center

Moderators: David B. Skinner, M.D.

James L. Cox, M.D.

4. REOPERATION FOR FAILED MITRAL VALVE REPAIR.

Marc Gillinov, M.D.*, Delos M. Cosgrove, M.D., Bruce W. Lytle, M.D., Paul C. Taylor, M.D.*, Robert W. Stewart, M.D.*, Patrick M. McCarthy, M.D., Nicholas G. Smedira, M.D.*, Derek Muehrcke, M.D* and Floyd D. Loop, M.D.

Cleveland, Ohio

Discussant: Tirone E. David, M.D.

Recurrent mitral regurgitation (MR) is a vexing complication of mitral valve (MV) repair. To determine the causes of failed MV repair, the surgical pathology of patients who underwent reoperation for a failed MV repair was examined. From 1986-1994, 2,548 patients underwent surgery for MR. Of these, 81 patients (3.1%) had 86 reoperations for recurrent MR after MV repair. Mean age was 59.2 ± 1.4 years (18-79 years); 55 were men. Primary valve pathology was degenerative in 47 patients (58%), rheumatic in 16 (20%), ischemic in 14 (17%), endocarditis in 3 (4%) and congenital in 1 (1%).

Time interval between initial MV repair and reoperation was 15.6 ±2.5 months. Findings at reoperation were:

Progression of primary valve disease was the most common cause of recurrent MR (46 patients [57%]). Rupture of previously shortened chordae was the mechanism of recurrent MR in 17 of 28 patients (61%) with progression of degenerative MV disease.

Operations included mitral valve replacement in 64 patients (79%) and repeat MV repair in 17 (21%). Five patients who had repeat MV repair required subsequent valve replacement. There were 6 hospital deaths (7.4%).

We conclude that: 1) progression of primary valve disease is the most common cause of late failure after MV repair; 2) chordal shortening is associated with late failure in patients with degenerative disease; and 3) repeat mitral valve repair results in successful treatment for a small minority of patients.

*By invitation

5. TRANSMYOCARDIAL LASER REVASCULARIZATION: RESULTS OF A MULTI-CENTER TRIAL USING TMLR AS SOLE THERAPY FOR END-STAGE CORONARY ARTERY DISEASE.

Keith A. Horvath, M.D.*, Lawrence H. Cohn, M.D., Denton A. Cooley, M.D., John R. Crew, M.D.*, O. Howard Frazier, M.D., Hartley P. Griffith, M.D., Kamuran Kadipasaoglu, Ph.D.*, Allan Lansing, M.D.*, Robert March, M.D.*, Mahmood R. Mirhoseini, M.D.* and Craig Smith, M.D.

Boston, Massachusetts; Houston, Texas; San Francisco, California; Pittsburgh, Pennsylvania, Louisville, Tennessee; Chicago, Illinois; Milwaukee, Wisconsin and New York, New York

Discussant: John L. Ochsner, M.D.

Transmyocardial laser revascularization was utilized as sole therapy for patients with ischemic heart disease not amenable to PTCA or CABG. This technique employs an 800W CO₂ laser to create transmyocardial channels for direct perfusion of the ischemic heart. Since 1992, 200 patients at eight U.S. hospitals, have undergone TMLR. One hundred seventy-five patients have 3-12 months follow-up for an accumulated 1190 patient/months of follow-up. Their age was 62 ± 11 years (mean ± SD) and their ejection fraction was 47 ± 12%. Eighty percent (140/175) had at least one previous CABG and 36% (63/175) had a prior PTCA. Preoperatively, the patients underwent nuclear SPECT perfusion scans to identify the extent and reversibility of their ischemia. These scans were repeated at 3, 6 and 12 months. Angina class (CCS) and admissions for angina were recorded. The peri-operative mortality was 8% (16/200). The data are expressed as mean ± SD with t-test for significance vs. preoperative values.

Improved perfusion was confirmed by PET scans at one center which demonstrated increased subendocardial vs. subepicardial resting perfusion at 12 months (0.96 ± 0.7 vs. 1.10 ± 0.02, p < 0.001, N = 11). In the year prior to their TMLR, the patients averaged 2.5 ± 1.7 admissions for angina; this decreased to an average of 0.3 ± 7 admissions in the year after the procedure (p = 0.00002).

These combined results indicate that TMLR may provide angina relief, decrease hospital admissions and improve perfusion in patients with severe coronary artery disease.

11:15 a.m. PRESIDENTIAL ADDRESS

I'd Like to be a Thoracic Surgeon

Mortimer J. Buckley, M.D., Boston Massachusetts

12:00 p.m. ADJOURN FOR LUNCH

*By invitation