TUESDAY AFTERNOON, May 7, 1991

1:45 p.m. SIMULTANEOUS SCIENTIFIC SESSION A - Congenital Heart Disease - Monroe Room

17. Hypoplastic Aortic Arch with Severe Coarctation in the Neonate: Repair Using Resection, Extended Aortotomy and Primary Anastomosis

GARY K. LOFLAND*, WILLIAM B. MOSKOWITZ*,

MONICA COBLE*, DANIEL PIERONI*,

ROBERT GINGELL * and ANDREW S. WECHSLER

Richmond, Virginia and Buffalo, New York

Although hospital mortality of isolated coarctation repair in infancy is less than 3%, coarctation presenting symptomatically in the neonatal period remains a surgical challenge, especially if there is associated aortic arch hypoplasia. Reported mortality rates for this lesion have ranged from 26 to 61%. Between July, 1987 and October, 1990, 50 consecutive infants (48 neonates) with significant arch hypoplasia and severe coarctation underwent surgical correction. Weights ranged from 1.6 to 3.5 kilograms. Cardiac anomalies included: VSD in 42 (84%), ASD in 37 (74%), TGA in 16 (32%), aortic valve anomalies in 10 (20%), single or common ventricle in 12 (24%), aberrant right subclavian artery in 4, mitral atresia and tricuspid atresia in 5 patients. Excluding PDA, 2.6 additional cardic anomalies were present per patient. Non cardiac anomalies included chromosomal abnormalities in 4 patients, broncho-pulmonary dysplasia in 2, renal failure in 2, cortical and brain stem dysfunction preoperatively in 4, and gastroschisis in 1 patient. Mean age of repair was 6.7 days. Mean weight at repair was 2.8 kilograms. All patients underwent left thoracotomy, ligation, division, and oversewing of the ductus arteriosus, resection of all ductal and coarctation tissue, extended aortotomy along the aortic arch and proximal descending thoracic aorta and primary anastomosis using 7.0 polypropylene suture. Length of the anastomoses were 1.2-1.7 cm. Patients with significant VSD underwent PA banding with VSD closure at 4-8 months postoperatively. Hospital stay was 13.8 +/- 2.3 days for term infants. Postoperative stay was 9 +/- 2 days with duration of mechanical ventilation 36 +/- 4 hours for the entire series. 4 patients had gradients between 5 and 10 mm of mercury secondary to residual hypoplastic segments proximal to the extent of aortotomy. These gradients had reduced to 0 by 1 month follow-up. 2 patients developed gradients of 15 to 20 mm of mercury at 8 months follow-up, both of whom were treated with coarctation revision at the time of VSD closure. 4 patients had unacceptable gradients following completion of repair at the time of the original surgery, and underwent augmentation of the coarctation repair with either reverse subclavian flap or anastomosis between base of left carotid and base of left subclavian arteries. There were no major complications which lengthened hospital stay. 1 peri-operative death occurred (2%) in a patient with critical aortic stenosis, small (5mm) aortic annulus and LVOTO. Late deaths have occurred in 4 patients between 1 and 6 months post operatively, all from causes unrelated to coarctation or coarctation repair. There were no gradients between upper and lower extremities in any patients at time of death. All patients have been followed with serial upper and lower extremity blood pressure determinations and serial echocardiograms. Thus, short term operative results with this aggressive approach to the hypoplastic aortic arch utilizing totally autologous tissues and a long anastomosis have been very gratifying with reduction in operative mortality from as high as 59% to 2%. These patients will continue to be followed closely for growth of all areas of the aorta including the anastomosis.

*By Invitation

SIMULTANEOUS SCIENTIFIC SESSION A - Congenital Heart Disease - Monroe Room

18. Risk of Recoarctation in Neonates and Infants Following Repair with Patch Aortoplasty, Subclavian Flap and the Combined Resection-Flap Procedure

CHARLES A. DIETL*, ALBERTO R. TORRES*,

RENE G. FAVALORO, CINDY L. FESSLER* and

GARY L. GRUNKEMEIER*

Portland, Oregon and Buenos Aires, Argentina

Between September 1980 and August 1988, forty-seven patients younger than 12 months (27 neonates and 20 infants), underwent repair of aortic coarctation, utilizing three surgical techniques: patch aortoplasty (group A: 5 neonates and 3 infants, mean age 4.5 months), subclavian flap (group B: 11 neonates and 8 infants, mean age 3.1 months), and the combined resection-flap procedure (group C: 11 neonates and 9 infants, mean age 2.7 months). There were 8 early deaths (3 in group A, 3 in group B and 2 in group C), and 2 late deaths (both in group B, after subsequent intracardiac surgery), which occurred in patients with complex coexisting anomalies. 37 patients (5 in group A, 14 in group B, and 18 in group C) were followed between 24 and 108 months (mean 62.8, 56.4 and 45.5 months respectively). Residual gradients were detected in 4 out of 5 patients in group A (range 0 to 60 mmHg, mean 25 mmHg), in 11 out of 14 patients in group B (range 0 to 40 mmHg, mean 18.2 mmHg), and in 1 out of 18 patients in group C (range 0 to 20 mmHg, mean 1.1 mmHg) (p<0.01). So far 4 patients operated during their neonatal period, with gradients greater than 30 mmHg, have required reoperation: 1/5 in group A (20% risk), 3/14 in group B (21% risk), and none in group C (0% risk) (p<0.01). In summary, residual gradients and risk of recoarctation are significantly higher when a patch or a subclavian flap were employed. The combined resection-flap procedure (an end-to-end anastomosis enlarged with a subclavian flap) is more effective in avoiding gradients and preventing recoarctation, specially in neonates.

*By Invitation

SIMULTANEOUS SCIENTIFIC SESSION A - Congenital Heart Disease - Monroe Room

19. Logical Approach for Surgical Management of Multiple VSD/118 Patients

CLAUDE PLANCHE*, ALAIN SERRAF*,

JACQUELINE BRUNIAUX*, FRANCOIS LACOUR-GAYET*,

RUTH OUAKNINE* and JEAN LOSAY*

Le Plessis Robinson, France

Sponsored by: John W. Kirklin, Birmingham, Alabama

From January 1980 through September 1990, 118 children underwent surgical closure of multiple VSD. Patients with associated major cardiac malformation were excluded. The mean age and the mean weight at operation were respectively 20 ± 22 months and 8 ± 4.4 kg. Fifty-one (43.2%) were below 1 year old.

Fifty-six children had pulmonary protection, either by previous pulmonary artery banding (n = 48) or by pulmonary valve stenosis, (n = 8). All other patients had severe pulmonary hypertension (mean systolic pressure 71.5 mmHg ± 22.3) and already disabling heart failure (NYHA: III - IV).

The surgical management was based on the localization of the defects and the ventricular dominance which were assessed pre and intra-operatively. Trabecular VSDs were always centered by the moderator band and were therefore divided into low trabecular, mid trabecular and high trabecular.

The perimembranous septum was involved in 89 cases, the trabecular in 113 and the infundibular in 6.

Fifty children had two large VSD, 22 had 3 VSD, 8 had 4 and thirty-eight patients presented the "swiss-cheese"form of the lesion.

Closure of the VSDs included Dacron patch and mattress sutures. They were always first approached through a right atriotomy, which was sufficient for complete repair in 74 cases. In mid trabecular VSDs, section of the moderator band (n = 20) allowed closure of all the defects with a single Dacron patch. In 44 patients the VSDs could not be closed only through a right atriotomy, and a right (n = 28) or a left (n = 14) particularly for low trabecular VSD or both right and left (n = 2) ventriculotomies were necessary to secure the repair.

In hospital mortality was 8.5% (70% CL: 11.9 - 6.5%, 10 patients). The causes of death were related to : low trabecular residual VSD in 5, pulmonary hypertension in 2, hypoplastic right (n = 1) or left (n = 1). ventricles and myocardial infarction in 1. Eighteen survivors had residual VSD. In 11 cases they were located in the lower part of the trabecular septum and mandate reoperation in 4 with 2 deaths. Four patients required a permanent pacemaker for complete AV-block. Morbidity was significantly increased in low trabecular VSD (n<0.001). All but 8 survivors were reviewed. Five years, actuarial survival rate and freedom from reoperation were respectively 89.8% and 95.9%.

We conclude that a surgical management of multiple VSDs based on the anatomy of the defects and on the ventricular dominance constitutes a logical approach to these patients, however patients with low trabecular multiple VSDs represent a group with higher risk of morbidity.

2:45 p.m. INTERMISSION - VISIT EXHIBITS

*By Invitation

3:15 p.m. SIMULTANEOUS SCIENTIFIC SESSION A - Congenital Heart Disease - Monroe Room

20. Conal Enlargement for Diffuse Subaortic Stenosis

SERAFIN Y. DeLEON, MICHEL N. ILBAWI,

RENE A. ARCILLA*, OTTO G. THILENIUS*,

WILLIAM R. WILSON*, DAVID A. ROBERSON*,

ELISE C. DUFFY* and JOSE A. QUINONES*

Oak Lawn, Illinois

Conal enlargement (CE) to relieve diffuse subaortic stenosis (SAS) was done on 12 patients over a 3½year period. Ages ranged from 2 weeks to 12 years (mean 4.4 ± 4). The SAS was due to tunnel outflow in 11 and malattached mitral valve in 1. Subaortic gradient ranged from 10-70 mm Hg (mean 50 ± 21). Seven had ventricular septal defect (VSD) (1 with interrupted aortic arch (IAA), 1 with partial anomalous pulmonary venous drainage) and 2 had endocardial cushion defects (BCD). SAS was distal to VSD in 4 and proximal to VSD in 3. In 8 patients, significant obstruction occurred 2-7 years (mean 4 ± 2) following simple resection of SAS (2), VSD closure (2), VSD closure and SAS resection (2) and ECD repair (2). In 3 infants, the tunnel outflow distal to a large VSD was enlarged and closed with the VSD. One infant also had IAA repair. In 3 patients with SAS proximal to a previously repaired VSD, transatrial CE through the VSD was performed. Another patient had transatrial CE and the remaining 5 patients had modified Konno (aortic valve preserved). There was no early or late death. Two patients had complete heart block (1 had left bundle branch block [LBBB] following previous SAS resection, 1 had concurrent attempted resection and CE). Echographic outflow gradients detected 12 days to 3½ years (mean 1.2 ± 1) post-operatively, ranged from 0-25 mm Hg (mean 7 ± 11) and were mainly at the aortic valve level. All patients are clinically well up to 3½ years of follow-up (mean 1.5 ± 1). We conclude that transatrial or transventricular CE (modified Konno) can be safely performed for diffuse SAS in infants and children. Pre-operative LBBB and attempted resection with CE may predispose to complete heart block.

*By Invitation

SIMULTANEOUS SCIENTIFIC SESSION A - Congenital Heart Disease - Monroe Room

21. The Relation of Right Ventricle and Pulmonary Artery Morphology and Treatment Protocols to Survival after Repair of Tetralogy of Fallot: A Two-Institution Study

JOHN W. KIRKLIN, RICHARD A. JONAS,

YASUHISA SHIMAZAKI* and

EUGENE H. BLACKSTONE

Birmingham, Alabama, Boston, Massachusetts and

Osaka, Japan

The cineangiograms were reviewed of 100 consecutive patients (1985-1990) with tetralogy and pulmonary stenosis and no prior procedure, in each of two institutions, Institution A (whose protocols were generally for routine primary repair) and B (whose protocols were generally for preliminary shunting in patients < 9-12 months old). The dimensions of the right ventricular outflow tract, pulmonary trunk (PT), and the entirety of the right (RPA) and left pulmonary arteries and their branches were measured, and related to early and intermediate term outcomes. The youngest patient was 1 day old at catheterization, the median age was 5.7 months, 18 (9%) had important coexisting cardiac anomalies, including complete AV canal, and 7 (3.5%) had large AP collateral arteries.

Survival for 1 /12, 1, and 3 years after study was 97 %, 91 %, and 90%, and was not different both overall and risk-adjusted (P=0.5) between Institutions. Median age at repair (n = 172) was 10.3 months at A, 18.7 at B. Survival overall for 1/12, 1 and 3 years after repair was 94%, 91%, and 91%, not different overall and risk-adjusted in the two institutions. The diameter (as Z-value) of the "annulus," and of the RPA just beyond its origin, and the presence of large AP collateral arteries (APCs) were risk factors for death, as were multiple VSDs, young age at repair, and Down syndrome. Institution, transannular patching, and shunting prior to repair were not. The decreased survival in patients receiving transannular patching (at 1/12, 1, and 3 years, was 90%, 85%, and 85% vs. 98%, 97%, and 97% without) was explained by the higher prevalence in them of severe pulmonary trunk and artery hypoplasia. The strength and shape of the risk factors indicated that survival for at least 12 months (age at repair 6 months, single VSD, no large APCs, no Down) was:

Anulus Z	Prox RPA Z	Survival	Anulus Z	Prox RPA Z	Survival	Anulus Z	Prox RPA Z	Survival
-3	>-3	98%	-6	>-3	97%	-8	>-3	94%
-3	≤-3	94%	-6	≤-3	89%	-8	≤-3	82%

The protocol of essentially routine primary repair provides as good survival as one of 2-stage repair for infants. In both protocols the probability of survival is related primarily to the degree of RV, PT, and PA hypoplasia, and the incremental risk of young age is now small (predicted 12 month survival after repair, anulus Z -3, RPA Z >-3, age 6 months 98%, age 1 month 94%).

*By Invitation

SIMULTANEOUS SCIENTIFIC SESSION A - Congenital Heart Disease - Monroe Room

22. Transposition of Great Arteries, Ventricular Septal Defect and Pulmonary Outflow Tract Obstruction: Rastelli or Lecompte Procedure?

PASCAL R. VOUHÉ, DANIEL TAMISIER*,

FRANCINE LECA * RUTH OUAKNINE*,

YVES LECOMPTE* and JEAN-YVES NEVEUX*

Paris, France and Milano, Italy

Sponsored by: Eduardo Arciniegas, Detroit, Michigan

Between Jan. 1, 1980 and Jan. 1, 1990, 62 pts underwent complete repair for TGA, VSD, POTO. Twenty-two pts (35%) (mean age = 97 ± 87 mths) underwent operation of the Rastelli type: the VSD was enlarged anteriorly in 8 cases, the right ventricle (RV) - pulmonary artery (PA) continuity was established using an extracardiac valved (9/22) or non-valved (13/22) conduit. There were 2 early deaths (9% - 70% CL = 39/0-20%) and one late death (5% - CL = 1%-16%). Late survival rate was 83% ± 9% at 5 years. Six pts (32% - CL = 20%-46%) underwent reoperation after a mean follow-up of 5.5 yrs (residual VSD in one, obstructed conduit in 5). At last follow-up (mean follow-up=4.3 yrs), all pts but one were in functional class I; residual RV-PA gradient (>25 mmHg) was present in 7 cases (37% - CL = 24%-51%). Forty pts (65%) (mean age = 40 ± 39 mths) underwent the Lecompte modification: the infundibular septum was completely resected when present (30/40), anterior translocation of the pulmonary bifurcation was performed in 32 cases, the RV-PA continuity was established by direct anastomosis without prosthetic conduit. There were 5 early deaths (12.5% -CL = 7%-20%) and one late death (3% - CL = 0%-9%). Late survival rate was 84% ± 6% at 5 years. Four pts (12% - CL = 6%-20%) underwent reoperation after a mean follow-up of 3.8 yrs (residual VSD in 2, residual POTO in 2). At last follow-up (mean follow-up=3.7 yrs), all pts were in functional class I; residual RV-PA gradient was present in 6 cases (18% - CL = 11%-27%).

Conclusions: 1) Both procedures provide satisfactory early and late results in patients with TGA, VSD, POTO. 2) The Lecompte procedure allows complete repair at a younger age (40 mths vs 97 mths - p=0.0007) and may reduce the need for reoperation (12% vs 32% - p=0.08) and the incidence of residual POTO (18% vs 37% - p=0.11).

*By Invitation

SIMULTANEOUS SCIENTIFIC SESSION A - Congenital Heart Disease - Monroe Room

23. Fenestrated Fontan with Delayed Catheter ASD Closure: Improved Results in High Risk Patients

GARY S. KOPF, CHARLES S. KLEINMAN*,

ZIYAD M. HIJAZI*, JOHN T. FAHEY*, MICHAEL L. DEWAR*

and WILLIAME. HELLENBRAND*

New Haven, Connecticut

In the past 12 months, all patients with univentricular hearts and two or more risk factors for a Fontan operation have undergone a fenestrated Fontan procedure with delayed catheter-device closure of the fenestration before discharge three patients had total cavo-pulmonary artery connections (TCPC) and three had direct right atrial-pulmonary artery connections. Ages ranged from 9 months to 2.5 years. Fenestration was carried out with a 4 or 5 mm aortic punch in the ASD patch or intraatrial baffle, depending on size of patient. Preoperative risk factors included increased pulmonary vascular resistance in 4, need for pulmonary artery reconstruction in 3, arrythmias in 2, and decreased ventricular function in 2.

Despite moderate postoperative desaturation, there were no operative deaths. Analysis of the length of ventilatory support, need for inotropic agents, amount of pleural drainage and length of hospital stay showed no significant difference with a matched control group of low risk patients. The fenestration was successfully closed in the cath lab with a catheter tipped umbrella device in 5 patients prior to discharge with marked improvement in arterial saturation, but a 2 to 3 mmHG rise in right atrial pressure and decrease in cardiac output in two patients. In addition one patient had con-committant pulmonary artery dilation and one had closure of a second small atrial septal defect undiscovered at the time of surgery. One patient was discharged with a small ASD due to high right atrial pressures.

In conclusion, the fenestrated Fontan procedure, with a carefully sized fenestration, can be accomplished in high risk patients with low mortality and low post-operative morbidity. Fenestrations can be closed in most cases with catheter tipped devices prior to discharge with maintenance of good hemodynamics. The technique may help lower morbidity and mortality for patients otherwise considered high risk or inoperable for the Fontan procedure.

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

*By Invitation

TUESDAY AFTERNOON, May 7, 1991

1:45 p.m. SIMULTANEOUS SCIENTIFIC SESSION B - General Thoracic Surgery - Lincoln Room

24. Solitary Brain Metastases from Non-Small Cell Lung Cancer: Results of Therapy

MICHAEL BURT*, MAREK WRONSKI*,

JOSEPH GALICICH*, NAEL MARTINI

and ROBERT GINSBERG

New York, New York

The treatment of patients with a solitary brain metastasis (SBM) from NSCLC has been evolving, with most centers recommending resection in patients with good performance status. In order to evaluate the long term results of therapy, we reviewed our 15 yr experience. Methods: Records of 185 consecutive patients who underwent resection of a SBM from NSCLC at our institution from 1974 to 1989 were reviewed. Survival was calculated by Kaplan-Meier method; comparisons by log rank analysis; multivariate analysis by Cox proportional hazards model; significance defined as p<0.05. Results: Age: 34-75 yr (median 54); M:F 1:1. Sixty-five (35%) were synchronous (SYN) and 120 (65%) metachronous SBM (META). Discounting the brain metastasis, 68 (37%) were stage 1,13 (7%) stage 2, 62 (33%) stage 3A, 30 (16%) stage 3B, and 12 (6%) stage 4. Histology included 130 (70%) with adeno, 39 (21%) epidermoid, and 16 (9%) large cell carcinoma. There was no significant difference in age, stage, or histology between SYN and META. Complete resection (CR) of the primary NSCLC was accomplished in 115 (63%) overall; 32 (49%) with SYN and 83 (69%) META. Of those having no or incomplete resection, most received external radiation therapy with or without chemotherapy. The overall survival was 1 yr: 55%, 2 yr: 27%, 3 yr: 18%, 5 yr: 13%, and 10 yr: 7% (median 14 mos). There was no significant difference in survival from time of diagnosis of SBM in SYN vs META. The median time to development of META was 12 mos. There was a significant increase in survival for patients with SYN undergoing CR of the lung primary (median 20.8 mos; n = 32) versus those not having CR (median 9.9 mos; n = 33). When stage (discounting the SBM) and resectability were analyzed by the Cox model, stage had no significant (p=0.97) effect, but resectability was still highly significant (p=0.002). The ten year survival of SYN with CR of the primary NSCLC was 16 percent. Conclusion: Patients who present with SYN, or develop a META SBM benefit from resection of the SBM. These data also suggest that complete resection of the primary NSCLC in patients undergoing resection of the SBM is important and translates into long term survival. In addition, the local stage of NSCLC, even if extensive, should not preclude resection of primary and SBM for prolonged survival.

*By Invitation

SIMULTANEOUS SCIENTIFIC SESSION B - General Thoracic Surgery - Lincoln Room

25. Wedge and Segmental Resection for Primary Lung Carcinomas

JOHN C. WAIN*, DOUGLAS J. MATHISEN,

ALAN D. HILGENBERG, ASHBY C. MONCURE

and HERMES C. GRILLO

Boston, Massachusetts

Primary lung cancer excision by parenchyma sparing (PS) methods, either wedge or segmental resection, may be used as a method of choice or to minimize the loss of non-neoplastic lung in patients with compromised pulmonary function. To ascertain the efficacy of PS for these indications, the results of 196 resections from 1978 to 1989 were reviewed. Patients included 94 males, 102 females, mean age 66 ± 10 years (range 29 - 91 years). PS was performed by choice in 128/196 (65%, Group I) or because of compromised pulmonary function (FEV1 ≤ 1.0 or <40% predicted, or prior pneumonectomy) in 68/196 (35%, Group II).

Eighty-six wedge and 110 segmental resections were performed. 96 patients underwent mediastinoscopy; all cases had intrathoracic node sampling. Operative mortality was 5/196 (3%). Complications included pneumonia (10), empyema (2), pulmonary embolism (3), myocardial infarction (3) and stroke (2).

Histologically, adenocarcinomas (98/196), squamous cell (54/196) and bronchoalveolar (28/196) carcinomas predominated. Pathologic staging revealed 164 Stage I (113 T1NO, 51 T2NO), 5 Stage II, 19 Stage III-a, 5 Stage III-b and 3 Stage IV lesions. For Stage I lesions, median survival was 44.7 months in Group I, 43.8 months in Group II (p=0.65). Local recurrence was seen in 6/128 (5%) in Group I, in 2/68 (3%) in Group II (p=0.69).

Parenchyma sparing wedge or segmental resections are effective techniques for lung cancer therapy with a low operative mortality and a low incidence of recurrence. No significant difference in survival or in the incidence of local recurrence was found when these methods were used electively for small tumors or to minimize loss of pulmonary tissue in patients with compromised pulmonary function.

*By Invitation

SIMULTANEOUS SCIENTIFIC SESSION B - General Thoracic Surgery - Lincoln Room

26. Anterior Pericardial Tracheoplasty for Congenital Tracheal Stenosis

DAVID A. HEIMANSOHN*, KENNETH K. KESLER*,

MARK TURRENTINE*, YOUSEF MAHOMED*,

LYNN MEANS*, BRUCE MATT* and JOHN W. BROWN

Indianapolis, Indiana

Congenital tracheal stenosis may present as a life threatening anomaly not relieved by endotracheal or tracheostomy intubation. Anterior pericardia! tracheoplasty (APT) has been utilized at our institution for congenital long segment tracheal stenosis (CLSTS) in infants with impending airway obstruction. These patients have been reviewed to assess the utility, limits and long term results with this technique.

Between 1984-1990, eight infants (age 1-24 mo.) (wt. 1-14 Kg.) with CLSTS have been evaluated with conventional radiographs, CT scans and bronchoscopy. All have required preoperative tracheal intubation to maintain ventilation. Seven have undergone APT through a median sternotomy approach on partial normothermic cardiopulmonary bypass. An average of 10 tracheal rings (range 5-22) were divided anteriorly and a patch of fresh autologous pericardium utilized to enlarge the trachea by 1.5 times the predicted diameter. Fine absorbable monofilament sutures using a running technique were used to attach the pericardium to all tracheal layers except the mucosa. After insertion, the patch and hypoplastic tracheal cartilages were suspended by interrupted sutures to sorrounding vascular and pericardial structures. These infants were sedated and paralyzed for 10 postoperative days while maintaining positive end-expiratory airway pressure to assure patch adherence to the mediastinal tissues. Repeat bronchoscopy was performed prior to extubation to assess stability of the repair.

All 7 infants survived with no patch dehiscence or wound infections. Five were extubated within 14 days and are asymptomatic. They remain free of bronchoscopic narrowing at 1 to 60 months follow-up. The remaining 2 patients were markedly improved but have residual stenosis above or below the operative site secondary to complications of prior tracheostomy. They however, are well palliated after 1 and 30 months. Our review of APT has demonstrated the safety, utility and at least medium-term benefit of this procedure in infants of any age and weight.

2:45 p.m. INTERMISSION - VISIT EXHIBITS

*By Invitation

3:15 p.m. SIMULTANEOUS SCIENTIFIC SESSION B - General Thoracic Surgery - Lincoln Room

27. A New Operation for the Treatment of Innominate Artery Compression of the Trachea

STEVEN M. CLARK*, WARREN W. BAILEY*

and JOHN A. HAWKINS*

Cincinnati, Ohio

Sponsored by: Tom D. Ivey, M.D., Cincinnati, Ohio

Innominate artery compression of the trachea (IACOT) is a well recognized cause of airway obstruction in infants and children. The innominate artery normally originates partially or completely to the left of the trachea in young children and can cause anterior compression of the trachea. Innominate artery suspension has been the standard technique for treating IACOT, but there have been problems with recurrence using this technique. The purpose of this paper is to describe a new technique, innominate artery reimplantation (IAR), and to report our results.

From June 1982 to June 1990, 22 children underwent IAR to correct their IACOT. Ages ranged from 6 weeks to 15 years with a median age of 8 months. All children were evaluated with microlaryngoscopy and bronchoscopy preoperatively to document anterior vascular compression of the trachea. Ten of these children had the diagnosis confirmed with MRI and another child with CT. Indications for operations were reflex apnea in 59.1% (13/22), recurrent bronchopulmonary infection in 18.2% (4/22), severe stridor in 18.2% (4/22), and exercise induced asthma and stridor in 4.5% (1/22).

IAR is performed via a median sternotomy without the use of car-diopulmonary bypass or a shunt. The innominate artery is mobilized and transected at its origin from the aortic arch. The artery is then reimplanted more proximally on the aortic arch using interrupted polypropylene suture. This places the origin of the innominate artery to the right of the trachea thereby alleviating anterior compression of the trachea.

There were no early or late deaths during the study. Follow up was complete in all patients and ranged from 3 weeks to 4 years (mean = 18 months). One patient had a postoperative wound infection. There were no neurologic deficits and all children had a normal brachial pulse at follow up. Twenty of the 22 patients (91%) were completely asymptomatic at follow up. Two patients (9%) had partial resolution of their symptoms at follow up. One of these patients had residual stridor and another patient had resolution of reflex apnea but continued bronchopulmonary infections. Both of these patients had complete resolution of tracheal compression on postoperative micro laryngoscopy and bronchoscopy.

In conclusion, IAR is a viable alternative to innominate artery suspension in the treatment of IACOT. IAR completely removes the anatomic substrate for compression of the trachea and can be performed with minimal morbidity and good long term results.

*By Invitation

SIMULTANEOUS SCIENTIFIC SESSION B - General Thoracic Surgery - Lincoln Room

28. Pulmonary Arterial Reactivity Following Transplantation: Differential Effects of Denervation and Rejection

VIRGINIA M. MILLER*, FOLKE NILSSON* and

CHRISTOPHER G.A. McGREGOR

Rochester, Minnesota and Gothenburg, Sweden

Little is known of blood vessel function in transplanted solid organs during rejection. The separate effects of denervation and rejection have not been elucidated. To study how these two components may affect pulmonary arterial function following lung transplantation, pulmonary arteries were studied from rejecting allotransplanted lungs, autotransplanted lungs and control nonoperated lungs. Pulmonary arteries were dissected, cut into rings and suspended in organ chambers for the measurements of isometric force. In selected rings the endothelium was removed deliberately so that endothelial and smooth muscle function could be studied separately. There was no significant difference between groups in contractions to potassium chloride suggesting no important functional smooth muscle atrophy. Smooth muscle contractions to norepinephrine and the endothelium-derived contractile protein endothelin were reduced in both transplanted groups compared to controls. In rings with endothelium contractions to angiotensin I were similar in control and autotransplanted groups but reduced significantly in the rejecting group. Serum levels of angiotensin converting enzyme were also reduced significantly during acute rejection: 9.9 ± 1.5 U/L prerejection and 4.2 ± 0.5 U/L postrejection, (n = 12). Relaxations to adenosine diphosphate which are dependent on the presence of intact endothelial cells were reduced significantly only in the rejecting group. Relaxations of the smooth muscle to histamine were greater in the autotransplanted arteries compared to control and were further increased significantly with rejection. These results suggest that pulmonary arterial function changes in transplanted lungs and that such changes are distinct following denervation alone compared with denervation accompanied by rejection. Altered function of the pulmonary arteries may affect vascular resistance in the transplanted rejecting lung. Further, circulating levels of angiotensin coverting enzyme may prove to be a useful indicator of acute pulmonary rejection.

*By Invitation

SIMULTANEOUS SCIENTIFIC SESSION B - General Thoracic Surgery - Lincoln Room

29. Single Lung Transplantation - Factors in Postoperative Infections

J. KENT TRINKLE, JOHN H. CALHOON*.

LARHEA NICHOLS*, J. ROGER DAVIS*,

CALIANN T. LUM* and FREDERICK L. GROVER

San Antonio, Texas

Single lung transplantation (SLTX) is a new option for patients with end-stage lung disease. SLTX evolved slowly due to problems with infection, rejection, preservation, and bronchial healing. Infection remains the most perplexing problem. Chi-Square Analysis was performed on risk factors for cytomegalovirus (CMV) and all postoperative infections (PI) in SLTX operations in 31 patients. Eighteen patients were on preoperative Prednisone. Each patient received postoperative cyclosporine, Imuran, and high-dose methylprednisolone followed by Prednisone. Nonrandomized cytolytic therapy varied between OKT3 (n = 10), ALG (n = 12), or none (n = 9).

PI occurred in 21 patients, 11 of which had CMV. There were no bronchial complications. Preoperative Prednisone did not correlate with PI (p=.641), CMV (p=.739), or death (p=.5347). Postoperative CMV resulted in death in 5 of 11 patients (p=.0766), but when two highly probable, but not culture-proven, deaths are included (p=.0097). With cytolytic therapy 17 of 22 patients had PI, compared to 3 of 9 with no cytolytic therapy (p=.0354). All PI with no cytolytic therapy were minor. However, CMV was present in 13 of 22 with cytolytic therapy, and 0 of 9 with no cytolytic therapy (p=.0003). CMV occurred in 9 of 10 patients with OKT3 compared to 4/12 with ALG (p=.0071). CMV occurred in 0/9 with no cytolytic (p=.0542) compared to ALG. Prophylactic Ganciclovir and immune globulin were used in 17 patients with only 2 CMV in 6 patients also receiving ALG. There was no difference in clinical incidence of rejection, an imprecise diagnosis in SLTX, in the three groups.

CONCLUSIONS: Preoperative Prednisone in SLTX does not increase bronchial complications, PI, CMV, or mortality. CMV is a serious complication in SLTX. Ganciclovir and immune globulin may be effective prophylaxis for CMV. OKT3 causes a significant increase in CMV. Cytolytic therapy with OKT3 or ALG increases the incidence of PI and CMV in SLTX patients and should not be used!

*By Invitation

SIMULTANEOUS SCIENTIFIC SESSION B - General Thoracic Surgery - Lincoln Room

30. Long Segment Colon Substitution for the Esophagus

DOUGLAS J. MATHISEN, JOHN C. WAIN*,

EARLE W. WILKINS, JR., HERMES C. GRILLO and

ASHBY C. MONCURE Boston, Massachusetts

Long segments of colon have been used for total esophageal substitution for neoplastic or non-neoplastic disorders. To determine the utility of this method of complete esophageal substitution, the use of long segment colon in a single institution from 1955 to 1989 was reviewed. 136 patients were identified - 100 males, 36 females, mean age 51 years (range 3 months - 83 years).

Indications for use were neoplasm in 88 (including 8 tracheoesophageal fistulas) and non-neoplastic disorders in 48 (intractable stricture-35, congenital atresia-10, motility disturbances-3). Colon was used for bypass in 80 or replacement in 56. Left colon was used in 100/136 (74%) and right colon in 36/136 (26%).

Major acute complications included ischemic necrosis (4/100 left colon, 6/36 right colon), cervical anastomotic leak (8) and acute non-vascular perforation (1). Thirty day operative mortality: neoplastic group 16% [14/88 -colon necrosis (7), respiratory failure (5), metastatic disease (1), sudden cardiac death (1)], non-neoplastic group 0%).

Among operative survivors, excellent function (no dysphagia, stable weight) was obtained in 88% (107/122) and good function (mild dysphagia, stable weight) in 10% (12/122). Late complications included proximal anastomotic stenosis (3), graft redundancy (3), bile reflux (2) and esophageal mucocoele (1). Median survival: neoplastic group 9 months (range 2 months -10 years), non-neoplastic group 7.75 years (range 2-25 years).

For selected neoplasms, when conduit choice is limited, or for non-neoplastic disorders, where operative mortality is low and long term function is adequate, long segments of colon are useful conduits for total esophageal substitution. Left colon is significantly less likely to develop ischemic necrosis (p<0.003).

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

International Ballroom

*By Invitation

TUESDAY AFTERNOON, May 7, 1991

1:45 p.m. SIMULTANEOUS SCIENTIFIC SESSION C - Cardiac Surgery - International Ballroom

31. Tricuspid Valvulectomy Without Replacement: 20 Years Experience

AGUSTINARBULU, INGIDA ASFAW*

and ROBERT J. HOLMES*

Detroit, Michigan

Since September, 1970, we have operated upon 55 patients with intractable right-sided endocarditis. All patients were Heroin addicts. Fifty-three underwent Tricuspid Valve Excision without replacement (TVE) and two had TVE and Pulmonic Valve Excision without replacement (TVE + PE). Twenty-four (44%) patients returned to their addiction. Six patients (11%) required insertion of a prosthesis: two days to ten years after the TVE in five, and 13 years after TVE + PE in one. In all these six, the indications for surgery was medically refractory right heart failure. Sixteen patients died (29%). Six were EARLY, (11%) within 45 days after the TVE. Only one (2%) of these was related to the TVE. The other five were due to uncontrollable infection. Ten (18%) deaths occurred LATE: nine months to 13 years after the TVE or TVE + PE. Nine of these were related to the drug addiction and one was due to progressive right ventricular failure two months after insertion of a bioprosthesis, 10 years after the TVE. Four of the deaths occurred in patients that required insertion of a tricuspid prosthesis: one on the 5th P.O. day due to low cardiac output (the only EARLY death related to TVE), another died two months later, (the LATE death due to progressive right ventricular failure), and two were due to drug addiction.

Of the 39 patients that are alive since the TVE or TVE + PE, 37 (67%) had not required insertion of a prosthesis. Only two (4%) had mild right ventricular failure. Thirty-five (63%) are hemodynamically stable and none had liver impairment. CONCLUSIONS: 1) Drug addiction is a serious recurrent and lethal disease. It must be carefully considered in the choice of operation for this type of patient; 2) Only 11 % (6/55) of patients that had a TVE or TVE + PE required the insertion of a prosthesis to control medically refractory right heart failure; 3) TVE and TVE + PE remain the operation(s) of choice in the treatment of intractable right-sided endocarditis among drug addicts; and 4) In a small percentage of patients TVE may lead to severe distention and permanent impairment of the right ventricular function.

*By Invitation

SIMULTANEOUS SCIENTIFIC SESSION C - Cardiac Surgery - International Ballroom

32. Reduction and Elimination of Systemic Heparinization During Cardiopulmonary Bypass: Experimental Basis and Clinical Application

LUDWIG K. VON SEGESSER*, BRANKO M. WEISS*,

ELIGIO GARCIA*, ARTHUR VONFELTEN*

and MARCO I. TURINA

Zurich, Switzerland

Heparin-coated perfusion equipment was compared to uncoated equipment during left-heart bypass (LHBP) with roller pump (canine experiments: n = 20; bovine experiments: n = 20) or centrifugal pump (bovine experiments: n= 10), and during closed chest cardiopulmonary bypass (CPB) (bovine experiments: n = 30), or open chest CPB (canine experiments: n =40). Improved biocompatibility of heparin-coated equipment was demonstrated by scanning electron microscopy, hematology, biochemistry, coagulation and hemodynamics. Absence of systemic heparinization resulted in improved hemostasis, superior hemodynamics, preserved renal function, and attenuated hormonal stimulation.

Heparin-coated equipment was clinically evaluated in three different groups of patients (n =46):

1) Resection of descending thoracic aortic aneurysms (n = 23) was performed with heparin-coated LHBP (n = 12) or partial CPB (n = 11) for distal protection and proximal unloading. A single dose of heparin (5000 I.U.) was given to facilitate the use of autotransfusion. All devices remained functional throughout the procedures and no systemic emboli were detected. The sole death in this series (1/24: 4%) occurred (unrelated to the technique) in a patient with ruptured thoraco-abdominal aneurysm requiring surgery in extremis. Paraparesis with spontaneous recovery occurred in 1 patient (1/24: 4%).

2)Coronary artery revascularization randomized for low (ACTMSOs) versus full (ACTMSOs) systemic heparinization was prospectively analyzed in 22 patients perfused with heparin-coated equipment. All patients survived the procedure and no myocardial infaction was diagnosed. Low dose of heparin (8041 ± 1270 I.U. versus 52500 ± 17100 I.U.: p<0.0005) resulted in reduced protamin requirements (7875 ± 1918 I.U. versus 31400 ± 14000 I.U.: p<0.0005), reduced blood loss (831 ± 373 ml versus 2345 ± 1815 ml: p<0.01), reduced blood transfusion requirements (281 ±415 ml versus 2731 ± 2258 ml: p<0.001) and less patients receiving blood products (5/12 versus 10/10: p<0.05).

3) Rewarming in accidental hypothermia by CPB was successfully performed without systemic heparinization in a patient with hypothermic cardiac arrest (23.3°C) and intracranial trauma.

Conclusion: CPB can be performed without systemic anticoagulation. Our preliminary clinical experience using equipment with improved biocom-patibility demonstrates reduced bypass morbidity.

*By Invitation

SIMULTANEOUS SCIENTIFIC SESSION C - Cardiac Surgery - International Ballroom

33. Surgery or Atrioventricular Node Reentry Tachycardia: Skeletonization of the Atrioventricular Node and Discrete Perinodal Cryosurgery

YOUSUFMOHAMED*, ROBERTD. KING,

DOUGLAS P. ZIPES*, WILLIAM M. MILES*,

LA WRENCE S. KLEIN* and JOHN W. BROWN

Indianapolis, Indiana

Surgical treatment options for interruption of atrioventricular node reentrant tachycardia (AVNRT) include: (1) skeletonization of the atrioventricular node (AVN) by dissecting it from most of its atrial inputs, (2) discrete cryosurgery of the perinodal tissues by applying a series of sequential cryole-sions to the atrial tissues immediately adjacent to the AVN. Both these techniques attempt to interrupt one of the dual AVN conduction pathways while preserving the other.

This report describes 17 consecutive patients (pts) who underwent surgical treatment, 10 pts with skeletonization of the AVN and 7 pts with discrete perinodal cryosurgery. There were 10 females and 7 males and their ages ranged from 28 to 56 years (mean 38). Two of the 17 pts had Wolff-Parkinson-White Syndrome and their accessory pathways were interrupted prior to ablating the AVNRT. All the procedures were performed in a normothermic beating heart while monitoring AV conduction closely. In the skeletonization technique, the right atrial septum was mobilized and the AVN exposed anterior to the tendon of the Todaro. The perinodal cryosurgery procedure was also performed through a right atriotomy and a series of sequential 3 mm cryolesions were placed around the borders of the triangle of Koch on the inferior right atrial septum. There were no operative deaths. Two pts who underwent the skeletonization operation, developed heart block requiring pacemaker therapy. At postoperative electrophysiology study, there were no echoes or AVNRT inducible in any of the 17 pts. All patients have remained free of arrhythmia recurrence and have required no anti-arrhythmic therapy after a follow-up of 5 to 28 months (mean 14).

In conclusion, both AVN skeletonization and perinodal cryosurgery successfully ablate AVNRT however, perinodal cryosurgery appears to be safer in avoiding heart block, is more easily performed and is our procedure of choice for the treatment of medically refractory AVNRT.

2:45 p.m. INTERMISSION - VISIT EXHIBITS

*By Invitation

3:15 p.m. SIMULTANEOUS SCIENTIFIC SESSION C - Cardiac Surgery - International Ballroom

34. Vein Graft Disease: The Clinical Impact of Stenoses in Saphenous Vein to Coronary Artery Bypass Grafts

BRUCE W. LYTLE, FLOYD D. LOOP,

MARLENE GOORMASTIC*, PAUL C. TAYLOR*

and DELOS M. COSGROVE

Cleveland, Ohio

The influence of coronary artery stenoses on patient survival and event-free survival is known but no studies have documented the long-term outcome of patients with stenoses in saphenous vein bypass grafts (SVG). We retrospectively studied 723 patients who underwent a postoperative angiographic study that documented a stenosis of 20-99% in at least one SVG and for whom the initial treatment plan was non-operative. Patients with only totally occluded SVGs or who underwent reoperation or PTCA within one year after the catheterization that documented the SVG stenosis were excluded. Six hundred nineteen patients had one, 98 had 2 and 6 had 3 stenotic SVGs. Follow-up (mean post-cath interval 83 months, range 1-237 months) documented survival of 83% and 68% and event-free survival of 66% and 43% at five and ten postcatheterization years, respectively. Cox regression analyses were used to identify predictors of late survival and event-free survival. For the entire group, moderate or severe impairment of left ventricular function (p<0.0001), increasing interval between operation and catheterization (p<0.0001), older age (p=0.0004), triple-vessel or left main coronary artery disease (p=0.0034), and left anterior descending (LAD) SVG stenosis (p=0.09) were associated with decreased late survival. Patients with an operation to catheterization interval ≥5 years were at particularly high risk and for that subgroup a stenotic SVG to LAD was a strong predictor of decreased survival (p=0.0001) and event-free survival (p=0.0001). Symptom status at the time of the catheterization and the degree of SVG stenosis did not significantly influence outcome. Patients ≥5 years postoperatively with a SVG to LAD stenosis ≥50% has survival of 67% and 45% at 2 and 5 postcatheterization years compared to 97% and 80% for those with a native coronary LAD stenosis ≥50% (p=0.003). Compared with native coronary stenoses, late vein graft stenoses are more dangerous. Late stenoses in saphenous vein grafts to the LAD coronary artery predict a high rate of death and cardiac events and are an indication for reoperation.

*By Invitation

SIMULTANEOUS SCIENTIFIC SESSION C - Cardiac Surgery - International Ballroom

35. Use of Inferior Epigastric Artery for Coronary By-Pass

JEAN-CLAUDE SCHOEVAERDTS*, MICHEL BUCHE*,

YVES LOUAGIE*, ROBERT DION*,

ER WIN SCHROEDER *, BAUDOIN MARCHANDISE*

and CHARLES CHALANT*

Yvoir and Brussels, Belgium

Sponsored by: Albert Starr, Portland, Oregon

During a learning period (Dec. 88-Dec. 89) 9 CABG operations using a free inferior Epigastric artery (IEA) and both in situ internal Mammary arteries (IMA) were performed in patients with three-vessel disease requiring complete revascularization without saphenous vein available. Favourable early and late angiographic controls and histological studies (Histol. similarity between IMA and IEA) encouraged us to start a prospective study.

MATERIAL: Since January 1990, 33 IEA were used in 32 patients (13 to distal right cor. artery, 11 to post-descending branch of RCA, 2 to posterolateral branch of RCA, 4 to Marginal Circumflex, 1 to Diagonal branch and 2 sequential IEA on 2 Marginal Circumflex branches). In addition, left IMA was anastomosed on LAD in all patients (as single or sequential graft) and right IMA in 28 patients on marginal Cx or distal RCA. The use of IEA was decided because of: no sitable saphenous vein in 12 patients, desire of complete arterial revascularisation in 12 young patients and 4 redo operations, no suitable RIMA in 4 patients (preop. angiographic evidence of unsuitability and/or severe emphysema).

Extraperitoneal approach of IEA is simple but requires standardised technique.

RESULTS: 28/32 patients underwent postoperative coronary angiographic control (on day 10 after operation) and all have accepted a 6 months postoperative angiographic control.

1. One death on postop day 2 from acute tamponnade

2. No postoperative myocardial infarction

3. 28 angiographic postop controls (day 10):

all 28 IEA grafts are patent (30/30) anastomoses are patent) similarly 53/53 IMA grafts (76/77 anastomoses) are patent

4. All patients belong to NYHA functional class I

CONCLUSIONS: If long term patency of IEA and IMA grafts remains comparable, the IEA could be a complementary material for coronary bypass (especially on distal RCA and distal Cx branches).

*By Invitation

SIMULTANEOUS SCIENTIFIC SESSION C - Cardiac Surgery - International Ballroom

36. Reactivity of Gastroepiploic and Internal Mammary Arteries: Relevance to Coronary Artery Bypass Grafting

REBECCA J. DIGNAN*, THOMAS YEH, JR. *

CORNELIUS DYKE*, K. FRANCIS LEE*,

GAR Y BENTON*, MAI DING* and

ANDREWS. WECHSLER

Richmond, Virginia

The GEA is an alternate conduit for CABG. This study tests the hypothesis that its vasoreactive properties are different from the IMA. Human GEA (n = 7) and IMA (n = 44) ring segments were mounted on a strain gauge in oxygenated, normothermic, physiologic saline. Segments were normalized for size according to compliance curves, and stretched to optimal resting length (90% of the internal circumference at 100 mmHg). Potassium chloride (KCL), serotonin (STN), and noradrenaline (NA) were chosen to simulate physiologic vasospasm. Contractions to KCL and a dose response curve to STN or NA were obtained. Sodium nitroprusside (SNP) was used to assess relaxation.

Artery	KCL	NA	EC50**	STN	EC50	SNP
GEA	17.6±1.5*	15.8±2.1	1.8E-7M	14.0±4*	0.9E-7M	-94±7%
(N), SEM	(23)	(10)	±.34E-7M	(7)	±0.25E-7M	(5)
IMA	12.1±0.64	16.1±1.3	2.8E-7M	4.2±0.6	1.6E-7M	-89±19%
(N), SEM	(117)	(19)	±1.4E-7M	(7)	±1.1E-7M	(21)
*p<0.05 by ANOVA; values are pressure expressed in mN/mm2 ± SEM %Percent relaxation of contraction **EC50: concentration which produces 50% maximum contraction

Thus, the GEA has increased reactivity (stronger contractions) to KCL (a depolarizing agent) and STN (a product of platelet aggregation) but equal reactivity compared to the IMA to NA (adrenergic) stimulation. The GEA is equally as sensitive (EC50) to NA and STN as the IMA. There is no difference in relaxation to SNP. These data suggest that prevention of platelet or KCL-induced vasospasm may be more important when the GEA is used as an alternate conduit for CABG, reinforcing consideration of platelet inhibitors in the peri-operative interval.

*By Invitation

SIMULTANEOUS SCIENTIFIC SESSION C - Cardiac Surgery - International Ballroom

37. Imparted Relaxation of the Human Mammary Artery After Temporary Clamping

JAMES D. FONGER*, XIMING YANG*,

RICHARD A. COHEN*,

CHRISTIAN C. HAUDENSCHILD*

and RICHARD J. SHEMIN

Boston, Massachusetts

The internal mammary artery (IMA) is now used routinely for coronary artery bypass grafting because of its long-term freedom from atherosclerosis. Preservation of the IMA endothelial cell lining may play an important role in both IMA vasoreactivity and resistance to atherosclerosis. Temporary occlusion of the vascular pedicle with external clamps has the potential for endothelial cell injury. We studied the degree of clamp injury and altered vasoreactivity caused by currently available hard and soft jaw clamps.

IMA specimens from 17 patients were harvested. Each specimen was divided into three vascular rings. A control ring was stored in saline while the other two were clamped for 30 minutes with either a hard or soft jaw clamp. Isometric tensions were measured in all three rings in an organ chamber and the rings were contracted with a thromboxane A₂ mimetic, U46619. Vascular relaxation was induced with the endoihelium-dependent drug acetycholine and the endothelium-indepenent drug sodium nitroprusside. Papaverine which is a direct smooth muscle relaxant was given after each trial. The rings were silver stained and graded for percentage of intact endothelial cells by an independent pathologist.

Endothelium-dependent maximal relaxation of the rings was significantly impaired from control after soft (20% vs 91 %; p<0.01) and hard (1% vs 91%; p<0.01) jaw clamping. Relaxation after hard jaw clamping was also significantly less than soft jaw clamping (1%vs 20%; p<0.05). Endothelium-independent maximal relaxation was not significantly impaired from control after soft jaw clamping (89% vs 97%) but was significantly impaired after hard jaw clamping compaired to control (73% vs 97%; p<0.01) and compared to soft jaw clamping (73% vs 89%; p<0.05). Papaverine produced complete relaxation of ail rings. Histologic grading of endothelial cell integrity demonstrated a significant reduction after soft jaw clamping versus control (39% vs 79%; p<0.01) and a further reduction with hard versus soft jaw clamping (15% vs 39%; p<0.02).

In conclusion, external occlusive pressure on the mammary artery pedicle significantly impairs mammary artery endolhelium-dependent relaxation after both soft and hard jaw clamping. Endothelium-independent relaxation was not effected by soft jaw clamping but was significantly impaired by hard jaw clamping. Soft jaw clamping caused significantly less impairment of both endothelium-dependent and independent relaxation. Papaverine will produce maximal relaxation in spite of these impairments. Histology confirmed that less endothelial cell damage occurs with soft jaw clamping. Since temporary occlusive clamping is necessary during the IMA anastomosis, soft jaw clamps significantly reduce the morphologic and physiologic dysfunction of the human internal mammary.

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

International Ballroom

7:00 p.m. MEMBERS' RECEPTION (Tickets Required)

International Ballroom West

*By Invitation