Long-term survival after thoracoscopic lung volume reduction: a multiinstitutional review

Background. It has been suggested that bilateral thoracoscopic lung volume reduction (BTLVR) yields significantly better long-term survival than unilateral thoracoscopic lung volume reduction (UTLVR).

Methods. All perioperative data were collected at the time of the procedure. Follow-up data were obtained during office visits or by telephone.

Results. A total of 673 patients underwent thoracoscopic LVR: 343 had either simultaneous or staged BTLVR and 330, UTLVR. As of July 1998, follow-up was available on 667 (99%) of the 673 patients with a mean follow-up of 24.3 months. The patients in the BTLVR group were significantly younger (62.6 ± 8.0 years versus 65.4 ± 8.1 years; p < 0.0001), had a higher preoperative arterial oxygen tension (69.7 ± 12 mm Hg versus 65.3 ± 11 mm Hg; p < 0.0001), and had a superior preoperative 6-minute walk performance (279.9 ± 93.6 m [933 ± 312 feet] versus 244.5 ± 101.4 m [815 ± 338 feet] p < 0.0001). There was no difference in the operative mortality rate between the two groups (UTLVR, 5.1%, and BTLVR, 7%). Actuarial survival rates for the UTLVR group at 1 year, 2 years, and 3 years were 86%, 75%, and 69%, respectively versus 90%, 81%, and 74%, respectively, for the BTLVR group (p = not significant).

Conclusions. Contrary to previous reports, survival after BTLVR was not superior to that after UTLVR even though the former group appeared to have a lower risk preoperatively because of younger age, higher arterial oxygen tension, more advantageous anatomy, and better functional status. Despite thoracoscopic LVR, the actuarial mortality rate approached 30% at 3 years, and this calls into question whether this procedure offers any survival advantage to patients with end-stage emphysema.     

Comparison of clinical results for unilateral and bilateral thoracoscopic lung volume reduction

Background. It is widely believed that bilateral thoracoscopic lung volume reduction (BTLVR) yields superior results when compared with unilateral thoracoscopic lung volume reduction (UTLVR) with regard to spirometry, functional capacity, oxygenation and quality of life results.

Methods. To address these issues, we compared the results of patients undergoing UTLVR (N = 338 patients) and BTLVR (N = 344 patients) from 1993 to 1998 at five institutions. Follow-up data were available on 671 patients (98.4%) between 6 and 12 months after surgery, and a patient self-assessment was obtained at a mean of 24 months.

Results. It was found that BTLVR provides superior improvement in measured postoperative percent change in FEV₁ (L) (UTLVR 23.3% ± 55.3 vs BTLVR 33% ± 41, p = 0.04), FVC(L) (10.5% ± 31.6 vs 20.3% ± 34.3, p = 0.002) and RV(L) (−13% ± −22 vs −22% ± 17.9, p = 0.015). BTLVR also provides a slight improvement over UTLVR in patient’s perception regarding improved quality of life (UTLVR 79% vs BTLVR 88%, p = 0.03) and dyspnea relief (71% vs 61%, p = 0.03). There was no difference in mean changes in Po₂ (mm Hg) (UTLV 4.5 ± 12.3 vs BTLVR 4.9 ± 13.3, p = NS), 6-minute walk (UTLVR 26% ± 66.1 vs BTLVR 31% ± 59.6, p = NS) or decreased oxygen utilization (UTLVR 78% vs BTLVR 74%, p = NS).

Conclusions. These data suggest that both UTLVR and BTLVR yield significant improvement, but the results of BTLVR seem to be superior with regard to spirometry, lung volumes, and quality of life.     

Bilateral versus single lung transplantation for chronic obstructive pulmonary disease: intermediate-term results

Background. There is controversy regarding the transplant procedure of choice in chronic obstructive pulmonary disease We reviewed our intermediate-term outcomes with single lung transplantation (SLT) versus bilateral lung transplantation (BLT).

Methods. We retrospectively reviewed 130 patients with chronic obstructive pulmonary disease: 84 underwent SLT, 46 BLT. The mean age was 51.1 ± 1.2 years for those who underwent BLT and 56.2 ± 0.7 years for those who underwent SLT (p < 0.0001). Male patients represented 65% of the BLT group and 46% of the SLT group (p = 0.04). Spirometry and 6-minute walk tests were obtained preoperatively and at 3- to 6-month intervals. Posttransplant survival and survival from time of onset of bronchiolitis obliterans syndrome were calculated by Kaplan-Meier method. The mean follow-up was 32.4 months.

Results. The 90-day mortality rate was 13.0% For BLT and 15.5% for SLT (p = 0.71). Actuarial survival rates at 1, 3, and 5 years were 82.6%, 74.6%, and 61.9% for BLT and 72.2%, 63.4%, and 57.4% for SLT; the favorable survival trend with BLT did not achieve statistical significance. There were no differences in preoperative spirometry or 6-minute walk tests. The improvements in forced expiratory volume in one second , forced vital capacity (FVC), and 6 MWT were significantly greater following BLT. The incidence of bronchiolitis obliterans syndrome was 22.4% in SLT and 22.2% in BLT; survival following onset of bronchiolitis obliterans syndrome was similar.

Conclusions. For patients with chronic obstructive pulmonary disease, BLT is associated with superior lung function, exercise tolerance, and a trend toward enhanced survival. Younger candidates may be best suited for BLT. Given the limited donor lungs, SLT remains the preferred alternative for all other patients.     

Ministernotomy versus median sternotomy for aortic valve replacement: a prospective, randomized study

Background. Minimally invasive aortic valve replacement reduces surgical trauma and, supposedly, postoperative pain, blood loss, and length of stay. A prospective, randomized study was designed to prove these theoretical advantages.

Methods. Forty patients undergoing isolated, elective aortic valve replacement were randomized into two equal groups. Patients in group M underwent aortic valve replacement through a ministernotomy (reversed or reversed ). In group S, a median sternotomy was used. The anesthetic and surgical protocol was identical for both groups. Pain was evaluated on a daily basis. Pulmonary function tests were performed preoperatively and before hospital discharge in all patients.

Results. There were two deaths in each group. Cross-clamp time was longer in group M: 70 ± 19 minutes versus 51 ± 13 minutes in group S (p = 0.005). There were no statistically significant differences between groups M and S in pump time (95 ± 20 minutes versus 83 ± 19 minutes), extubation time (9.9 hours in both groups), chest drainage (479 ± 274 mL/ 24 hours versus 355 ± 159 mL/ 24 hours), transfusion requirements (27% in both groups), pain evaluation (1.34 ± 1.3 versus 2.15 ± 1.5), length of stay (6.2 ± 2.3 days versus 6.3 ± 2.5 days), and cosmetic appraisal. Forced vital capacity decreased 26% from preoperative reference values in group M and 33% in group S (p = not significant). Forced expiratory volume in 1 second decreased 22% and 35%, respectively (p = not significant).

Conclusions. This study has failed to prove the theoretical advantages of minimally invasive aortic valve replacement. With this technique, cross-clamp time is longer than with a median sternotomy.     

Improved clinical outcomes in patients undergoing coronary artery bypass grafting with coronary endarterectomy

Background. Coronary artery bypass grafting (CABG) with coronary endarterectomy (CE) has been associated with increased morbidity and mortality. We sought to evaluate the impact of recent advances in operative and perioperative management on outcomes after CE.

Methods. One hundred fifty-one consecutive patients undergoing first-time CABG with CE between 1991 and 1997 were compared with a concurrent group of 757 patients undergoing CABG without CE (Control).

Results. Age, gender, left ventricular ejection fraction, percent nonelective were similar in both groups. Compared with control, the CE group had a higher incidence of hypertension (80% versus 71%, p = 0.02), diabetes (42% versus 32%, p = 0.01), prior myocardial infarction (MI) (68% versus 59%, p = 0.05), peripheral vascular disease (36% versus 16%, p < 0.001), renal failure (15% versus 4%, p < 0.001), and three-vessel coronary disease (81% versus 70%, p = 0.007), resulting in higher Society of Thoracic Surgeons database predicted mortality (4.9 ± 5.9% versus 3.9 ± 4.6%, p = 0.05). Despite the higher risk profile of the CE group, hospital mortality (CE 2.0%, Control 1.2%) and the incidence of major complications such as cerebrovascular accident (CVA) (0.7% versus 1.5%), major respiratory complications (8% versus 5%), and postoperative MI (3% versus 1.4%) were similar between the groups (all p = NS). In a multiple logistic regression analysis, prolonged cardiopulmonary bypass time was an independent predictor of postoperative MI (odds ratio 1.2, CI 1.05 to 1.39, p < 0.01) and the use of heparin-bonded cardiopulmonary bypass circuits of reduced MI rate (odds ratio 0.25, CI 0.08 to 0.76, p < 0.01). Mean follow-up for 94% of patients was 30 ± 19 months (range 1 to 83 months). Five-year survival after CE was 70 ± 5%, with 96% of patients in Canadian Cardiovascular Society class I/II.

Conclusions. In a contemporary series of carefully selected patients, mortality and major complications after CE are now similar to CABG without CE. CE itself is not an independent predictor of postoperative MI. Functional class of hospital survivors is excellent.     

Reversibility of Cardiac Dysfunction After Valve Replacement in Elderly Patients With Severe Aortic Stenosis

Background. The role of aortic valve replacement for aortic stenosis has not been fully defined in terms of the postoperative reversibility of cardiac dysfunction and pulmonary hypertension in elderly patients.

Methods. Cardiac function, assessed by radioisotope ventriculography and catheterization data, was evaluated before and after operation, and their results were compared between preoperative and postoperative data in each group of younger patients (<69 years, group I, n = 29) and elderly patients (≥70 years, group II, n = 21).

Results. One month postoperatively the peak ejection rate determined by radioisotope ventriculography improved significantly in comparison with the preoperative value in elderly patients (preoperatively, 228 ± 38 versus postoperatively, 319 ± 116% end-diastolic volume per second, p < 0.05), although their preoperative peak ejection rate was severely depressed. The postoperative peak filling rate of the elderly group was not completely reversible to almost normal value, whereas that of the younger group was completely reversible. Early diastolic peak filling rate (one-third peak filling rate) was not reversible in both two groups. Pulmonary hypertension in the elderly patients was reversible to postoperative almost normal pulmonary artery pressure despite the severity of aortic stenosis (systolic pulmonary artery pressure preoperatively, 37 ± 16 mm Hg versus postoperatively, 25 ± 5 mm Hg, p < 0.02; diastolic pulmonary artery pressure preoperatively, 15 ± 6 mm Hg versus postoperatively, 10 ± 4 mm Hg, p < 0.05).

Conclusions. Both cardiac dysfunction, reflected by reduction of peak ejection rate, and pulmonary hypertension in elderly patients with severe aortic stenosis were reversed, reaching almost normal values 1 month after operation.     

Partial versus full sternotomy for aortic valve replacement

Background. Recent trends suggest that smaller incisions reduce postoperative morbidity. This study tests the hypothesis that a partial upper sternotomy improves patient outcome for aortic valve replacement.

Methods. A group of 50 patients who underwent aortic valve surgery through a partial upper sternotomy (group I) were compared to 50 patients who underwent aortic valve replacement through a median sternotomy during the same time period (group II). The mean age (60 ± 2 versus 63 ± 2 years; mean ± SEM) and preoperative ejection fractions (53 ± 2 versus 54 ± 2) were similar. Operations were performed with central cannulation, and antegrade/retrograde blood cardioplegia.

Results. There was one death in each group. No differences were found in aortic occlusion time, mediastinal drainage, transfusion incidence, narcotic requirement, length of stay, or cost. The incidence of pleural and pericardial effusions was increased (18.4% versus 3.9%, p < 0.03), and the need for postoperative inotropic support was higher (38.7% versus 19.6%, p < 0.03) in the partial sternotomy group.

Conclusions. Aortic valve replacement can be performed through a partial sternotomy with results comparable to full sternotomy. The partial sternotomy offers a cosmetic benefit, but does not significantly reduce postoperative pain, length of stay, or cost.     

Optimizing timing of early extubation in coronary artery bypass surgery patients

Background. This study was designed to assess the safety and efficacy of extubation performed within 4 hours of the patient’s arrival in the surgical intensive care unit after coronary artery bypass graft surgery.

Methods. A matched retrospective cohort study was performed including 412 consecutive patients undergoing isolated coronary artery bypass graft surgery between January 1996 and December 1997, constituting the experience of a single surgeon (J.H.L.). Early extubation (defined as extubation within 8 hours of arrival at the surgical intensive care unit) was achieved in 308 of 412 patients (75%). Patients extubated in fewer than 4 hours after arrival (n = 200) were compared with patients extubated within 4 to 8 hours (n = 108).

Results. Four deaths occurred in 412 patients, for an overall operative mortality rate of 1.0%. Patients extubated in fewer than 4 hours were younger than those extubated 4 or more hours after admission (62 versus 67 years old, respectively; p = 0.001), more likely to be male (74% versus 63%, p < 0.05), and had shorter aortic cross-clamp times (49.4 ± 15.0 versus 53.5 ± 14.0 minutes, p < 0.05) and cardiopulmonary bypass (CPB) times (65.2 ± 18.6 versus 72.1 ± 19.1 minutes, p < 0.05) compared to patients extubated later. Moreover, patients extubated in fewer than 4 hours had a shorter surgical intensive care unit length of stay (33.8 ± 25.7 versus 43.1 ± 43.0 hours, p < 0.05) and shorter postoperative length of stay (5.4 ± 2.4 versus 6.2 ± 2.6 days, p = 0.01) than those extubated later.

Conclusions. Extubation in fewer than 4 hours may offer a substantial advantage in terms of accelerated recovery compared with extubation within 4 to 8 hours. Very few differences in clinical parameters were noted between the two groups we studied, suggesting that efforts to reduce extubation times further might be worthwhile.     

Vascular delay and intermittent stimulation: keys to successful latissimus dorsi muscle stimulation

Background. The goal of this study was to obtain physiologically significant increases in peak left ventricular (LV) systolic pressure and stroke volume with latissimus dorsi muscle (LDM) stimulation in cardiomyoplasty (CMP). We hypothesized that preserving LDM integrity by vascular delay and intermittent stimulation would significantly increase LDM cardiac assistance.

Methods. In 4 control dogs and 12 dogs that had undergone a vascular delay (VD) procedure, LV dysfunction was induced by intracoronary microsphere injections. Cardiomyoplasty surgery was performed 14 days later, followed by progressive LDM conditioning. In the control dogs and in 6 of the VD dogs, the LDM was stimulated 24 hours per day (VD plus constant stimulation [CS]). In the other 6 VD dogs, LDMs were stimulated on a daily schedule of 10 hours on and 14 hours off (VD plus interrupted stimulation [IS]). Latissimus dorsi muscle stimulated beats were compared with nonstimulated beats 9 weeks later.

Results. In the control dogs, LDM stimulation had minimal effects. In VD + CS and VD + IS, LDM stimulation increased peak LV pressure, stroke volume, stroke work, and stroke power (p < 0.05). However, these changes were greater in the VD + IS group, in which LDM stimulation increased peak aortic pressure by 17.6 ± 1.7 mm Hg, peak LV pressure by 19.7 ± 1.1 mm Hg, peak positive LV dp/dt by 398 ± 144 mm Hg per second, stroke volume by 5.1 ± 0.7 mL, stroke work by 10.9 ± 0.9 gm · m, and stroke power by 122.7 ± 11.6 gm · m per second (p < 0.05 compared with VD + CS). Quantitative morphometric analysis showed minimal LDM degeneration in the VD + IS group (7.5% ± 1.1%), and VD + CS group (10.5% ± 4.5%) compared with the control group (29.5% ± 4.5%, p < 0.05).

Conclusions. VD and IS considerably increased the LV assistance with LDM stimulation. Further studies of this combined approach to CMP should be planned.     

Heat shock improves recovery and provides protection against global ischemia after hypothermic storage

Background. Improved methods of donor heart preparation before preservation could allow for prolonged storage and permit remote procurement of these organs. Previous studies have shown that overexpression of heat-shock protein 72 provides protection against ischemic cardiac damage. We sought to determine whether rats subjected to heat stress with only 6-hour recovery could acquire protection to a subsequent heart storage for 12 hours at 4°C.

Methods. Three groups of animals (n = 10 each) were studied: control, sham-treated, and heat-shocked rats (whole-body hyperthermia 42°C for 15 minutes). After 12-hour cold ischemia hearts were reperfused on a Langendorff column. To confirm any differences in functional recovery, hearts were then subjected to an additional 15-minute period of warm global ischemia after which function and lactate dehydrogenase enzyme leakage were measured.

Results. Heat-shocked animals showed marked improvements compared with controls in left ventricular developed pressure (63 ± 4 mm Hg versus 44 ± 4 mm Hg, p < 0.05) heart rate × developed pressure (13,883 ± 1,174 beats per minute × mm Hg versus 8,492 ± 1,564 beats per minute × mm Hg, p < 0.05), rate of ventricular pressure increase (1,912 ± 112 mm Hg/second versus 1,215 ± 162 mm Hg/second, p < 0.005), rate of ventricular pressure decrease (1,258 ± 89 mm Hg/second versus 774 ± 106 mm Hg/second, p < 0.005). Diastolic compliance and lactate dehydrogenase release were improved in heat-shocked animals compared with controls and sham-treated animals. Differences between heat-shocked animals and control or sham-treated animals were further increased after the additional 15-minute period of warm ischemia. Western blot experiments confirmed increased heat-shock protein 72 levels in heat-shocked animals (> threefold) compared with sham-treated animals and controls.

Conclusions. Heat shock 6 hours before heart removal resulted in marked expression of heat-shock protein 72 and protected isolated rat hearts by increased functional recovery and decreased cellular necrosis after 12-hour cold ischemia in a protocol mimicking that of heart preservation for transplantation. Protection was further confirmed after an additional 15-minute period of warm ischemia.     

Effects of Cardiomyoplasty on Right Ventricular Filling During Volume Loading

Background. Although cardiomyoplasty (CMP) is thought to improve ventricular systolic function, its effects on ventricular diastolic function are not clear. Especially the effects on right ventricular diastolic filling have not been fully investigated. Because pericardial influences are more pronounced in the right ventricle than in the left ventricle, CMP with its external constraint may substantially impair right ventricular diastolic filling.

Methods. Fourteen purebred adult beagles were used in this study. Seven underwent left posterior CMP, and 7 underwent a sham operation with a pericardiotomy and served as controls. Four weeks later, the hemodynamic effects of CMP were evaluated by heart catheterization before and after volume loading (central venous infusion of 10 mg/kg of 4.5% albumin solution for 5 minutes).

Results. In the CMP group, mean right atrial pressure and right ventricular end-diastolic pressure increased significantly from 3.1 ± 1.2 mm Hg to 6.1 ± 2.0 mm Hg (p < 0.001) and from 4.0 ± 1.8 mm Hg to 9.6 ± 2.5 mm Hg (p < 0.001), respectively. Volume loading in the control group did not significantly increase either variable. Right ventricular end-diastolic volume and stroke volume did not change significantly (from 53 ± 9.3 mL to 60 ± 9.0 mL and from 20 ± 2.3 mL to 21 ± 3.2 mL, respectively) in the CMP group. In the control group, however, right ventricular end-diastolic volume and stroke volume increased significantly from 45 ± 7.7 mL to 63 ± 14 mL (p < 0.05) and from 18 ± 4.3 mL to 22 ± 4.2 mL (p < 0.05), respectively.

Conclusions. These results suggest that CMP may reduce right ventricular compliance and restrict right ventricular diastolic filling in response to rapid volume loading because of its external constraint.     

Anatomical risk factors for mortality and cardiac morbidity after arterial switch operation

Background. The arterial switch operation (ASO) is the treatment of choice for transposition of the great arteries.

Methods. Anatomical risk factors on mortality and morbidity were analyzed retrospectively in 312 patients who underwent ASO between 1982 and 1997.

Results. Survival was 95%, 92%, and 92% after 30 days, 5, and 10 years, respectively. Operative survival improved after 1990 to 97% (p < 0.001). Risk factors for operative mortality were complex anatomy (p = 0.018), coronary anomalies (p = 0.008), and prolonged bypass time (p < 0.001). Determinants of late mortality were coronary distribution (p = 0.03), position of the great arteries (p = 0.0095), bypass time (p = 0.047), and aortic coarctation (p = 0.046). After a follow-up of 3.6 ± 2.7 years (0.1 to 14.9 years), 98% had good left ventricle function, 94% were in sinus rhythm, 2.4% had moderate to severe pulmonary stenosis, 0.3% had significant aortic regurgitation, and 1% had coronary stenosis. Freedom from reoperation was 100%, 96%, and 94% after 1, 5, and 10 years, respectively. No preoperative anatomic parameter correlated with long-term morbidity.

Conclusions. ASO can be performed with low operative mortality (< 5%) and long-term morbidity. Malformations associated with complex transposition of the great arteries influence early and late mortality.     

The efficacy of intraoperative internal intercostal nerve block during video-assisted thoracic surgery on postoperative pain

Background. Video-assisted thoracic surgery (VATS) is widely used for many thoracic surgical procedures. Postoperative pain is less after VATS than after conventional thoracic surgery, but is still significant. The objective of this study was to assess the efficacy of thoracoscopic, internal intercostal nerve block in alleviating immediate postoperative pain.

Methods. Thirty-two patients underwent VATS bilateral sympathectomy for the treatment of hyperhidrosis. The patients were randomly divided into two groups with similar demographic and preoperative physiologic parameters. Group A (n = 16) was submitted to thoracoscopic, internal intercostal nerve blocks performed at T2, T3, and T4 intercostal levels using 3 cc of 0.5% bupivacain in each intercostal space. The injections were performed bilaterally, immediately after the sympathectomy, through the same port. Group B (n = 16) underwent bilateral thoracic sympathectomy without the block. During the immediate postoperative period, heart rate, blood pressure, respiratory rate, pain score, and analgesic requirements were monitored every 30 minutes.

Results. No morbidity was recorded in association with the thoracoscopic, internal intercostal nerve block. The mean heart rates (77 ± 6 vs 89 ± 12 beats per minute, p < 0.001), respiratory rates (15 ± 2 vs 18 ± 3 respirations per minute, p < 0.01), pain score (1.9 ± 0.6 vs 2.7 ± 0.5, p < 0.01), and postoperative analgesic requirements (20 ± 18 vs 50 ± 21 mg pethidine HCL, p < 0.001) were significantly lower in group A. There was no significant difference in blood pressures.

Conclusions. Thoracoscopic, internal intercostal nerve block with bupivacain 0.5% during VATS is safe and effectively reduced the immediate postoperative pain and analgesic requirements.     

Reduced incidence of atrial fibrillation with minimally invasive direct coronary artery bypass

Background. Atrial fibrillation (AF) is a frequent complication after coronary artery bypass graft (CABG) surgery. The purpose of this study was to determine the incidence of postoperative AF after minimally invasive direct coronary artery bypass (MIDCAB) in comparison with CABG.

Methods. Between November 1995 and May 1997, 96 MIDCAB procedures were performed. During the same period, 42 patients underwent traditional single CABG using the left internal mammary artery graft (S-CABG). The incidence of in-hospital AF, defined as a sustained episode requiring treatment, was compared between the two groups.

Results. There was no difference in age, ejection fraction, or preoperative risk score between the groups. The use of β-blockers before or after surgery was not different. The incidence of postoperative AF in the first 6 weeks after surgery was 4% (4 of 96) for MIDCAB and 28% (12 of 42) for S-CABG (p = 0.003). Patients with postoperative AF were older than those without AF (AF 75.5 ± 13.2, non-AF 64.4 ± 10.9, p = 0.005). MIDCAB patients had a shorter hospital stay (4.0 ± 1.2 versus 7.0 ± 5.1 days, p < 0.05). Increased hospital stay attributable to AF was 0.6 ± .5 days for MIDCAB and 0.9 ± .2 days for S-CABG patients. There were no hospital deaths in either group.

Conclusions. The incidence of postoperative AF after single vessel bypass surgery is reduced to a very low level after MIDCAB in comparison with CABG.     

Calcitonin Gene-Related Peptide-Induced Preconditioning Improves Preservation With Cardioplegia

Background. Our recent work has shown that calcitonin gene-related peptide (CGRP) may play an important role in mediation of ischemic preconditioning. Therefore, we tested the hypothesis that CGRP-induced preconditioning protects against myocardial damage after prolonged cardioplegic arrest in isolated rat hearts.

Methods. Six groups were studied: the control, ischemic preconditioning, and CGRP-pretreated groups for both 4- and 8-hour hypothermic ischemia. All hearts were arrested using St. Thomas Hospital cardioplegia, and then reperfused with normothermic Krebs-Henseleit solution for 60 minutes after the 4- or 8-hour hypothermic ischemic period. Hearts were subjected to two cycles of 5-minute ischemia and 10-minute reperfusion in the ischemic preconditioning group. In the CGRP-pretreated group, Krebs-Henseleit solution containing CGRP (5 × 10⁻⁹ mol/L) was substituted for the ischemic period.

Results. At 30 minutes of reperfusion after 4-hour storage, left ventricular pressure (mm Hg) and its first derivative (dp/dt_max, mm Hg/s) in the control, ischemic preconditioning, and CGRP groups were 65.2 ± 5.93 and 1,170 ± 119, 94.13 ± 4.93 and 1,825 ± 145.83, and 85.47 ± 4.17 and 1,900 ± 123.13, respectively (p < 0.01). After 8-hour storage, left ventricular pressure (mm Hg) and dp/dt_max (mm Hg/s) in the same groups were 51.07 ± 5.83 and 815 ± 107.17, 83.47 ± 6.54 and 1,480 ± 120.91, and 84.8 ± 8.49 and 1,396 ± 126.16 (p < 0.01). Ischemic preconditioning and CGRP-induced preconditioning also significantly reduced the release of myocardial enzymes.

Conclusions. The present studies suggest that ischemic preconditioning protects against ischemia-reperfusion injury even after 8 hours of hypothermic preservation in isolated rat hearts, and that CGRP exerts preconditioning-like cardioprotection.     

Reperfusion injury significantly impacts clinical outcome after pulmonary transplantation

Background. Reperfusion injury after pulmonary transplantation can contribute significantly to postoperative pulmonary dysfunction. We hypothesized that posttransplantation reperfusion injury would result in an increase in both in-hospital mortality and morbidity. We also hypothesized that the incidence of reperfusion injury would be dependent upon the cause of recipient lung disease and the interval of donor allograft ischemia.

Methods. We performed a retrospective study of all lung transplant recipients at our institution from June 1990 until June 1998. One hundred patients received 120 organs during this time period. We compared two groups of patients in this study: those experiencing a significant reperfusion injury (22%) and those who did not (78%).

Results. In-hospital mortality was significantly greater in patients experiencing reperfusion injury (40.9% versus 11.7%, p < 0.02). Posttransplantation reperfusion injury also resulted in prolonged ventilation (393.5 versus 56.8 hours, p < 0.001) and an increased length of stay in both the intensive care unit (22.2 versus 10.5 days, p < 0.01) and in the hospital (48.8 versus 25.6 days, p < 0.03). The incidence of reperfusion injury could not be attributed to length of donor organ ischemia (221.5 versus 252.9 minutes, p < 0.20). The clinical impact of reperfusion injury was significantly greater in patients undergoing transplantation for preexisting pulmonary hypertension (6/14) than those with chronic obstructive pulmonary disease or emphysema alone (6/54) (42.9% versus 11.1%, p < 0.012).

Conclusions. Clinically significant pulmonary reperfusion injury increased in-hospital mortality and morbidity resulting in prolonged ventilation, length of stay in the intensive care unit, and cost of hospitalization. The incidence of reperfusion injury was not dependent upon the duration of donor organ ischemia but increased with the presence of preoperative pulmonary hypertension. These findings suggest that recipient pathophysiology and donor allograft quality may play important roles in determining the incidence of reperfusion injury.     

Surgical treatment of acute type A dissection: is rupture a risk factor?

Background. The purpose of this study was to evaluate the significance of aortic rupture on clinical outcome in patients after aortic repair for acute type A dissection.

Methods. One hundred and twenty patients underwent aortic operations with resection of the intimal tear and open distal anastomosis. Median age was 60 years (range 16 to 87); 78 were male. Thirty-six patients had only ascending aortic replacement, 82 had hemiarch repair, and 2 had the entire arch replaced. Retrograde cerebral perfusion was utilized in 66 patients (53%). Rupture defined as free blood in the pericardial space was present in 60 patients (50%). Univariate and multivariate analyses were performed to assess the risk factors for mortality and neurologic dysfunction.

Results. Overall hospital mortality rate was 24.2% ± 4.0% (± 70% confidence level) but did not differ between patients with aortic rupture or without (p = 0.83). The incidence of permanent neurologic dysfunction was 9.4% overall, 10.5% with rupture and 8.3% without rupture (p = 0.75). Multivariate analysis revealed absence of retrograde cerebral perfusion and any postoperative complication as statistically significant indicators for in-hospital mortality (p < 0.05). Overall 1- and 5-year survival was 85.3% and 33.7%; among discharged patients, survival in the nonruptured group was 89% and 37%, versus 81% and 31% in the ruptured group (p = 0.01).

Conclusions. Aortic rupture at the time of surgery does not increase the risk of hospital mortality or permanent neurologic complications in patients with acute type A dissections. However, aortic rupture at the time of surgery does influence long-term survival.     

Retrograde cerebral perfusion for aortic arch surgery: analysis of risk factors

Background. Retrograde cerebral perfusion (RCP) has been widely adopted during aortic arch surgery under hypothermic circulatory arrest (HCA). However, the risks in terms of mortality and morbidity in aortic arch surgery using HCA with RCP have not yet been confirmed.

Methods. The present study is a retrospective review of 249 patients who underwent aortic arch surgery at three Japanese cardiovascular centers where RCP is a routine adjunct. The median age was 65 years, and 38 patients were more than 75 years old. The pathology in the aortic arch was atherosclerotic aneurysm in 133 patients and dissection in 116. Seventy patients had surgery on an emergency basis. Surgery was performed through a median sternotomy in 182 patients and through a left thoracotomy in 67. Using HCA with RCP, graft replacement of the total aortic arch was performed in 109, the distal arch in 63, and the ascending aorta and hemi-arch in 66; 11 patients had patch repair.

Results. The overall hospital mortality was 25/249 (10%), and 12/70 (17%) in emergent surgery. Stroke developed in 11 patients (4%). The median duration of RCP was 46 minutes (range, 5 to 95). Univariate analysis of risk factors revealed that an age of 75 years or more (p < 0.001), and urgency of surgery (p = 0.02) affected hospital mortality. Multivariate logistic analysis revealed that pump time (p = 0.0001), age (p = 0.0001) and RCP time (p = 0.05) are the most significant risk factors for mortality. The risk factors for mortality and neurological morbidity combined are pump time (p = 0.0001), age (p = 0.0002), and urgency of surgery (p = 0.07); RCP time is marginally significant (p = 0.15).

Conclusions. The dominant risk factors for mortality and morbidity are pump time, urgency of the surgery, and age. RCP is a simple and useful adjunct for aortic arch surgery with up to 80 minutes of HCA, although prolonged RCP is a risk factor for mortality and morbidity.     

Predicting Feasibility of Biventricular Repair of Right-Dominant Unbalanced Atrioventricular Canal

Background. In right-dominant unbalanced atrioventricular (AV) canal, there are no criteria to judge adequacy of the left ventricle for biventricular repair. The purpose of this study was to test the hypothesis that right ventricular volume overload in this condition results in right-to-left septal bowing and contributes to the appearance of a small left ventricle.

Methods. Five consecutive neonates and young infants (age range, 23 days to 5 months; median age, 3 months) with right-dominant unbalanced complete AV canal underwent biventricular repair. Preoperative and postoperative echocardiographic measurements of left (LV) and right ventricular size and AV valve component size were made. Potential LV volume was assessed preoperatively using a theoretic model that assumed a normalization of septal bowing.

Results. There was no perioperative mortality; 1 patient died 71 days postoperatively of problems related to the left AV valve. Preoperatively, all patients had severe LV hypoplasia, with a mean end-diastolic indexed true LV volume of 14.8 ± 9.1 mL/m², indexed potential LV volume of 32.0 ± 18.8 mL/m², left AV valve to total AV valve ratio of 0.30 ± 0.06, and LV to right ventricular long-dimension ratio of 0.65 ± 0.1. Postoperatively, all patients had indexed true LV volumes greater than 30 mL/m² (mean volume, 35.6 ± 3.9 mL/m²), and the left AV valve to total AV valve ratio and the LV to right ventricular long-dimension ratio increased to 0.42 ± 0.03 and 0.88 ± 0.11, respectively. Both preoperative potential and true LV volumes correlated well with postoperative true LV volumes: r = 0.90 (p = 0.040) and r = 0.93 (p = 0.023), respectively. Increases in LV length and left AV annulus size indicated contributions of volume loading and surgical patching to the right of the ventricular crest to the increase in LV size.

Conclusions. In our small series, preoperative indexed potential LV volume of 15 mL/m² or greater (present in all patients) allowed biventricular repair of right-dominant unbalanced AV canal. Any previous criteria for LV hypoplasia in this condition need to be reconsidered. This study also has implications for other right-sided volume-loaded lesions in which the left ventricle initially is judged to be hypoplastic but in which biventricular repair may be feasible.     

Intermittent Antegrade Tepid Versus Cold Blood Cardioplegia in Elective Myocardial Revascularization

Background. The ideal temperature for blood cardioplegia administration remains controversial.

Methods. Fifty-two patients who required elective myocardial revascularization were prospectively randomized to receive intermittent antegrade tepid (29°C; group T, 25 patients) or cold (4°C; group C, 27 patients) blood cardioplegia.

Results. The two cohorts were similar with respect to all preoperative and intraoperative variables. The mean septal temperature was higher in group T (T, 29.6° ± 1.1°C versus 17.5° ± 3.0°C; p < 0.0001). After reperfusion, group T exhibited significantly greater lactate and acid release despite similar levels of oxygen extraction (p < 0.05). The creatine kinase-MB isoenzyme release was significantly lower in group T (764 ± 89 versus 1,120 ± 141 U · h/L; p < 0.04). Hearts protected with tepid cardioplegia demonstrated significantly increased ejection fraction with volume loading, improvement in left ventricular function at 12 hours, and decreased need for postoperative inotropic support (p < 0.05). The frequency of ventricular defibrillation after cross-clamp removal was lower in this cohort (p < 0.05). There were no hospital deaths, and both groups had similar postoperative courses.

Conclusions. Intermittent antegrade tepid blood cardioplegia is a safe and efficacious method of myocardial protection and demonstrates advantages when compared with cold blood cardioplegia in elective myocardial revascularization.