Comparison of different porcine models simulating myocardial cold ischemia of pediatric donor hearts

BACKGROUND

Our team previously identified a stem cell-derived cardioprotective additive that can be added to standard cardioplegia to extend myocardial viability during prolonged myocardial cold ischemic time (CIT) in rodent models. The purpose of this study was to utilize a porcine model to compare in-vivo versus ex-vivo porcine simulation of CIT that accompanies cardiac transplantation in humans, in order to determine an optimal method for translation of our studies to larger animals.

METHODS

Eight 39-55 kg Yorkshire X pigs were randomly assigned to either in-vivo or ex-vivo simulation. After administration of general anesthesia and endotracheal intubation, baseline measurement of left ventricular performance was obtained via transesophageal echocardiography (TEE). After midline sternotomy and heparin administration, the aorta was cross-clamped and two liters of HTK-Custodiol were introduced via the aortic root. The in-vivo method utilized cold ischemic heart storage in the chest cavity while supporting the experimental animal with cardiopulmonary bypass (CPB). The ex-vivo method involved standard cardiac procurement, cold ischemic storage outside of the body, and subsequent cardiac reperfusion utilizing cardiac reanimation in a Langendorff heart perfusion mode. After CIT, measurements of post-ischemic left ventricular performance were obtained via echocardiography. Results are presented as: Mean ± Standard Deviation (Median, Minimum-Maximum).

RESULTS

Weight (kilograms) was similar in the in-vivo group and the ex-vivo group: 44 ± 1.8 (44, 42-46) versus 44 ± 5.1 (43.5, 39-51), respectively. Cold ischemic time (minutes) was longer in the ex-vivo group: 360 ± 0 (360, 360-360) versus 141 ± 26.7 (149, 102-163). Temperature (degrees Celsius) was colder in the ex-vivo group: 8 ± 0 (8, 8-8) versus 16.5 ± 4.2 (16, 12-16).In the in-vivo group, baseline ejection fraction and ejection fraction after CIT were: 48.25% ± 14.95% (48.5%, 33%-63%) and 41.25% ± 22.32% (41.5%, 20%-62%), respectively. In the ex-vivo group, baseline ejection fraction and ejection fraction after CIT were: 56.4% ± 5.9% (57%, 50%-67%) and 60.4% ± 7.7% (61.5%, 51.9%-67%), respectively.

CONCLUSION

The ex-vivo technique is suitable to evaluate cardioplegia additives that may substantially extend myocardial tolerance to cold ischemia.

Safe sternal reentry in patients with large thoracic aortic pseudoaneurysms

Sternal reentry for ascending aorta pseudoaneurysm repair presents a formidable challenge because of the risk of aneurysm rupture and hemorrhage. We describe two cases of large pseudoaneurysms at high risk for rupture during sternal reentry in which the chest was safely entered by use of an anterior sternal retraction technique. Several other methods for sternal reentry have been reported; however, the reliability and efficiency of the described technique make it the preferred method for sternal reentry for pseudoaneurysms at our institution.

Close antiplatelet therapy monitoring and adjustment based upon thrombelastography may reduce late-onset bleeding in HeartMate II recipients

OBJECTIVES

Bleeding is the most common complication of HeartMate II and is partially attributable to platelet dysfunction; however, antiplatelet therapy is arbitrary in most centres. We investigated how antiplatelet therapy adjustment with thrombelastography affects late-onset bleeding.

METHODS

Thrombelastography was used to adjust antiplatelet therapy in 57 HeartMate II recipients. Kaplan-Meier survival curves and Cox proportional hazard ratio model were used to identify predictors of late-onset bleeding in univariate and multivariate analysis. Finally, late-onset bleeding rate in our study was compared with the reported rates in other studies in the literature, all of which did not use any test to monitor or adjust antiplatelet therapy.

RESULTS

Mean follow-up was 347 days. Eighteen late-onset bleeding events occurred in 12 patients, a late-onset bleeding rate of 12/57 (21%) or 0.21 events/patient-year. The Kaplan-Meier survival curves demonstrated that late-onset bleeding was more common in the destination therapy cohort (P = 0.02), in patients older than 60 years (P = 0.04) and in females (P = 0.01), none of which was significant in multivariate analysis at a significance level of 0.05. To further investigate the higher bleeding rate in elderly patients, thrombelastography parameters were compared between younger and older patients at the age cut-off of 60 years which demonstrated a prothrombotic change the day after device implantation in younger patients that was absent in the elderly. There was also a trend towards higher requirement for antiplatelet therapy in younger patients while on device support, but the difference did not reach statistical significance. The average late-onset or gastrointestinal bleeding rate among seven comparable studies in the literature that did not use any monitoring test to adjust antiplatelet therapy was 0.49 events/patient-year.

CONCLUSIONS

Our study implicates that antiplatelet therapy adjustment with thrombelastography may reduce late-onset bleeding rate in HeartMate II recipients. Bleeding was more common in the elderly recipients and analysis of thrombelastography data suggests that a less aggressive antiplatelet therapy regimen could potentially lower bleeding rate in this vulnerable population.

Discrepancies between clinical and autopsy diagnoses in lung transplant recipients

We sought to investigate the role of autopsy diagnoses in lung transplantation by comparing the clinically derived cause of death with autopsy deduced cause of death in a cohort of lung transplant recipients. We retrospectively reviewed all consecutive autopsy findings on lung transplant recipients transplanted between March 1994 and March 2007. We reviewed medical records and our lung transplant database to determine the clinical diagnosis of cause of death based on the clinical assessment and discharge summary at the time of death. Our study showed that 21% of the autopsies performed on lung transplant recipients at our institution revealed findings unsuspected at the time of death. Myocardial infarction, pulmonary embolism, high grade acute cellular rejection and infections were the most frequently missed diagnoses. The autopsy remains a useful tool in confirming diagnostic accuracy in lung transplant recipients.

Late unilateral pulmonary edema in single lung transplant recipients

In this study we describe 3 single lung transplant recipients who developed unilateral pulmonary edema in the setting of cardiac and renal dysfunction. All 3 patients responded to diuresis with clinical and radiographic improvement. Unilateral cardiogenic pulmonary edema should be considered in the differential diagnosis of dyspnea and unilateral radiographic infiltrates in single lung transplant recipients.

Intraoperative contralateral pneumothorax during single-lung transplantation

Contralateral intraoperative tension pneumothorax is a rare complication of thoracic surgical procedures. Here we present three cases of tension pneumothorax that developed during single-lung transplantation for emphysema and pulmonary fibrosis. To the best of our knowledge, this is only the second report of contralateral intraoperative tension pneumothorax during single-lung transplantation. A high index of clinical suspicion is required for the detection of this potentially catastrophic complication.

Effect of Sildenafil on Pulmonary Artery Pressure, Systemic Pressure, and Nitric Oxide Utilization in Patients With Left Ventricular Assist Devices

BACKGROUND

Pulmonary artery hypertension can complicate the early postoperative care of patients with left ventricular assist devices (LVADs). Inhaled nitric oxide (INO) is frequently used to manipulate pulmonary resistance after LVADs have been placed. We evaluated the effect of oral sildenafil therapy on pulmonary artery pressure, systemic pressure, and nitric oxide utilization.

METHODS

After Institutional Review Board approval, the records of 10 consecutive adult patients with LVADs and pulmonary hypertension who received sildenafil were reviewed. Demographics, surgical history, INO use, inotrope requirements, and hemodynamic response to oral sildenafil at multiple intervals were collected. Hemodynamic data were analyzed with a two-way analysis of variance of repeated measures with correction for multiple comparisons.

RESULTS

There were 8 men and 2 women with 6 Heartmate XVE LVADs and 4 Thoratec LVADs (both, Thoratec, Pleasanton, California). When weaning was attempted, 8 patients who received INO demonstrated rebound pulmonary hypertension or increased right heart dysfunction. All patients were on inotropic therapy with dobutamine and milrinone. Sildenafil produced a significant reduction in pulmonary artery systolic pressure within 90 minutes of oral administration (p = 0.042). Significant changes in systolic blood pressure, mean arterial pressure, systemic vascular resistance, and heart rate were not observed. All 8 patients receiving INO were weaned within 12 hours without recurrent pulmonary hypertension. All 10 patients were weaned from inotropic support within 72 hours. No patient suffered right-side heart failure requiring intervention.

CONCLUSIONS

Oral sildenafil represents a useful adjunctive therapy for patients with LVADs. In our series, it provided additional reduction of pulmonary artery pressure, and facilitated weaning from INO and inotropes without deleterious hemodynamic consequences.

Managing the Post-Left Ventricular Assist Device Patient

The implantation of ventricular assist devices allows the opportunity for patients with intractable heart failure to have improved quality and quantity of life. The devices may be implanted after failed attempts to wean from bypass, as a bridge to transplantation, or as destination therapy. Key issues following the implantation of assist devices include the prevention of right ventricular failure, appropriate pharmacologic management, prevention and management of infection, and detection and treatment of device dysfunction.

Comamonas (Pseudomonas) testosteroni endocarditis

Comamonas testosteroni has rarely been implicated as a human pathogen. We report a case of infectious endocarditis due to this organism, occurring in a 49-year-old man. The posterior leaflet of the mitral valve contained a 1 x 1 cm vegetation and showed myxoid degeneration and acute inflammation. The patient had no evidence of reinfection after 32 months. The infection was almost certainly community acquired, as is usually true for this organism.

Oral Sildenafil Reduces Pulmonary Hypertension After Cardiac Surgery

BACKGROUND

Treatment of postoperative pulmonary hypertension with intravenous (IV) pulmonary vasodilators is hampered by the lack of selectivity. Inhaled nitric oxide produces selective pulmonary vasodilation; however, it requires a special device, and weaning can cause rebound. Oral sildenafil is a phosphodiesterase type V inhibitor. Sildenafil can produce sustained pulmonary vasodilatation in patients with hypoxic or primary pulmonary hypertension; however, experience with postoperative pulmonary hypertension is limited. We report our initial experience with eight patients who received oral sildenafil as adjunctive therapy for postoperative pulmonary hypertension

METHODS

We reviewed the charts of eight adult patients with postoperative pulmonary hypertension who received oral sildenafil (25 to 50 mg) to facilitate weaning of IV (milrinone, nitroglycerine, and sodium nitroprusside) and inhaled (nitric oxide) pulmonary vasodilators. Hemodynamic data were recorded before and 30 and 60 minutes after the initial dose of sildenafil.

RESULTS

After the initial dose of sildenafil, mean pulmonary artery pressure was reduced by 20% and 22% at 30 and 60 minutes, respectively (p < 0.05). Pulmonary vascular resistance index decreased by 49% and 44% at 30 and 60 minutes, respectively (p < 0.05). Sildenafil had no clinically significant effects on cardiac index, mean arterial pressure, or systemic vascular resistance. Subsequent doses of sildenafil were administered at regular intervals, allowing successful weaning of concomitant pulmonary vasodilators.

CONCLUSIONS

Oral sildenafil is an effective agent for treatment of postoperative pulmonary hypertension and can be used to facilitate weaning of inhaled and IV pulmonary vasodilators.

Measurement of cardiac output before and after cardiopulmonary bypass: Comparison among aortic transit-time ultrasound, thermodilution, and noninvasive partial CO2 rebreathing

OBJECTIVES

A noninvasive continuous cardiac output system (NICO) has been developed recently. NICO uses a ratio of the change in the end-tidal carbon dioxide partial pressure and carbon dioxide elimination in response to a brief period of partial rebreathing to measure CO. The aim of this study was to compare the agreement among NICO, bolus (TDCO), and continuous thermodilution (CCO), with transit-time flowmetry of the ascending aorta using an ultrasonic flow probe (UFP) before and after cardiopulmonary bypass (CPB).

DESIGN

Prospective, observational human study.

SETTING

Veterans Affairs Medical Center Hospital.

PARTICIPANTS

Sixty-eight patients.

METHODS

Matched sets of CO measurements between NICO, TDCO, CCO, and UFP were collected in 68 patients undergoing elective CABG at specific time periods before and after separation from CPB. After anesthetic induction, all patients had an NICO sensor attached between the endotracheal tube and the breathing circuit, a PAC floated into the pulmonary artery for TDCO and CCO monitoring, and a UFP positioned on the ascending aorta and used for the reference CO. Bland-Altman analysis was used to compare the agreement among the different methods.

MEASUREMENTS AND MAIN RESULTS

Bland-Altman analysis of CO measurements before CPB yielded a bias, precision, and percent error of 0.04 L/min +/- 1.07 L/min (44.8%) for NICO, 0.18 L/min +/- 1.01 L/min (41.7%) for TDCO, and 0.29 L/min +/- 1.40 L/min (57.5%) for CCO compared with simultaneous UFP CO measurements, respectively. After separation from CPB (average 29 mins), bias, precision, and percent error were -0.46 L/min +/- 1.06 L/min (37.3%) for NICO, 0.35 L/min +/- 1.39 L/min (46.1%) for TDCO, and 0.36 L/min +/- 1.96 L/min (64.7%) for CCO compared with UFP CO measurements, respectively.

CONCLUSIONS

Before initiation of CPB, the accuracy for all 3 techniques was similar. After separation from CPB, the tendency was for NICO to underestimate CO and for TDCO and CCO to overestimate it. NICO offers an alternative to invasive CO measurement.

Acute neuropsychological functioning following cardiosurgical interventions associated with the production of intraoperative cerebral microemboli

Coronary artery bypass graft (CABG) and valve replacement (VR) surgical patients underwent neuropsychological assessment 1-2 days prior to surgery; 7-10 days postsurgery; and 1 month following hospital discharge. A group of matched healthy controls was tested at identical intervals. Cerebral microemboli in both middle cerebral arteries were quantified during surgery using Doppler sonography. Neuropsychological testing results revealed that the CABG and VR groups did not differ from one another at any assessment point. However, surgical patients performed more poorly than healthy controls across all assessments. Surgical patients, as a group, demonstrated a mild decline in attentional functioning and learning efficiency at the 7-10 day follow-up, but these difficulties essentially returned to baseline by the 1-month follow-up. Intraoperative microemboli counts were not significantly associated with postsurgical neuropsychological functioning in either the CABG or VR group.

Oxidized low-density lipoprotein receptor LOX-1 and apoptosis in human atherosclerotic lesions

BACKGROUND

Lectin-like oxidized LDL receptor-1 (LOX-1), a novel receptor for oxidized low-density lipoprotein, mediates oxidized low-density lipoprotein-induced apoptosis of endothelial cells, monocyte adhesion to endothelium, and phagocytosis of aged cells. The present study examined the role of LOX-1 and apoptosis in human atherosclerotic lesions.

METHODS AND RESULTS

Grafted vein (n = 8), human carotid artery endarterectomy (n = 11), and normal human internal mammary artery (n = 8) specimens were used to study the expression of LOX-1 and apoptosis. LOX-1 expression was determined by reverse transcriptase-polymerase chain reaction, Western analysis, and immunostaining. Presence of apoptosis was determined by fluorescent in situ nick end-labeling staining and by the presence of poly (ADP-ribose) polymerase protein (an apoptotic marker). Expression of LOX-1 was significantly increased in atherosclerotic grafted vein and carotid artery specimens compared with that in normal arteries. LOX-1 was expressed in endothelial cells, macrophages, and smooth muscle cells. LOX-1 was extensively expressed in the new blood vessels in the core of advanced atherosclerotic lesions. Double immunostaining showed LOX-1 expression to be colocalized with apoptotic cells. Fluorescent in situ nick end-labeling staining showed that the apoptotic cells were present mostly in the rupture-prone regions of the atherosclerotic plaque.

CONCLUSION

These observations indicate that LOX-1 is extensively expressed in the proliferated intima of grafted veins and in advanced atherosclerotic carotid arteries. Further, LOX-1 is colocalized with apoptotic cells. These observations may relate to the phenomenon of plaque rupture, and provide targets for developing new therapies.

Analysis of early deaths after isolated lung transplantation

STUDY OBJECTIVES

To determine the causes of death in patients dying within 30 days after lung transplantation at the University of Florida, to assess the importance of several diagnostic modalities for determining the causes of their decline, and to construct an algorithm for the evaluation of patients with severe respiratory compromise occurring early after lung transplantation.

DESIGN

Retrospective review of medical records and pathology slides from all patients dying within 30 days after lung transplantation, and biopsy specimen diagnoses from all lung allograft recipients at the University of Florida.

PATIENTS

Nine deaths occurred during the first 30 days after transplantation among 117 patients undergoing 123 isolated lung transplantation operations.

RESULTS

Infections accounted for the greatest number of deaths (bacterial pneumonia, four patients; catheter-related bacteremia, one patient). Persistent pneumonia confirmed by biopsy specimen was usually accompanied by histologic manifestations of acute cellular rejection and was associated with poor patient outcome (ie, death or subsequent development of bronchiolitis obliterans syndrome). In two patients, antibody-mediated rejection either was the immediate cause of death (hyperacute rejection, one patient) or preceded a fatal case of pneumonia (accelerated antibody-mediated rejection, one patient). Other causes of death included hypoxic-ischemic encephalopathy secondary to an intraoperative cardiac arrest (one patient), pulmonary venous thrombosis with bacterial colonization of the thrombotic material (one patient), and ischemic reperfusion injury (one patient). In most patients, more than one type of diagnostic technique was needed to ascertain the cause of the catastrophic decline.

CONCLUSIONS

The causes of early posttransplant death in our patient group included infections, antibody-mediated rejection, hypoxic-ischemic encephalopathy secondary to cardiac arrest, pulmonary venous thrombosis, and ischemic reperfusion injury. Because these processes often demonstrate overlapping clinical and morphologic features requiring multiple diagnostic techniques for resolution, a systematic multimodality approach to diagnosis is advantageous for determining the causes of decline in individual patients and for estimating the incidences of the different causes of early graft and patient loss in the lung transplant population.

Results of a randomized, prospective, multicenter trial of mycophenolate mofetil versus azathioprine in the prevention of acute lung allograft rejection

BACKGROUND

Although the use of mycophenolate mofetil (MMF) has reduced the incidence of acute rejection in heart and kidney allograft recipients, its role in lung transplantation remains controversial. Therefore, we conducted a randomized, prospective, open-label, multicenter study in lung transplant recipients to determine whether MMF decreases episodes of acute allograft rejection when compared with azathioprine (AZA).

METHODS

Between March of 1997 and January of 1999, 81 consecutive lung transplant recipients from two centers were prospectively randomized to receive cyclosporine, corticosteroids, and either 2 mg/kg per day of AZA or 1 g twice daily of MMF. The primary study endpoint was biopsy-proven acute allograft rejection over the first 6 months posttransplant. Secondary endpoints included clinical rejection, cytomegalovirus (CMV) infection, adverse events, and survival. Surveillance bronchoscopies were performed at 1, 3, and 6 months, or if clinically indicated. Pathologists interpreting the biopsy results were blinded to the randomization. Results were analyzed according to intention-to-treat. Between group comparisons of means and proportions were made by using two sample t tests and Fisher's exact tests, respectively. Six-month survival was calculated by the Kaplan-Meier method and compared by the log rank test.

RESULTS

Thirty-eight patients were prospectively randomized to receive AZA, and 43 MMF. The incidence of biopsy proven grade II or greater acute allograft rejection at 6 months was 58% in the AZA group and 63% in the MMF group (P=0.82). The 6-month survival rates in the MMF and AZA groups were 86% and 82%, respectively (P=0.57). Rates of CMV infection and adverse events were not significantly different between the two groups.

CONCLUSIONS

Acute rejection rates and overall survival at 6 months are similar in lung transplant recipients treated with either MMF- or AZA-based immunosuppression.

Unilateral vs. bilateral ultrasound in the monitoring of cerebral microemboli

We used bilateral transcranial Doppler to monitor the number of microembolic events (ME) in the left and right middle cerebral arteries of 29 patients during cardiac surgery that required extracorporeal circulation. Based on a previously published study, we hypothesized that the commonly used method of doubling unilateral ME counts to obtain an estimated bihemispheric load would result in significant errors of estimation. In our sample, estimated bihemispheric counts were inaccurate by an average of 18% (range 0--80%). Despite this large range of error, calculation of Cronbach's alpha revealed that actual error due to unreliability (4%) was small relative to the large variation in ME counts across subjects in this patient series. These findings suggest that unilateral monitoring is sufficient when the goal is to characterize a given subject's ME load within the context of the other subjects in the sample. However, when precise ME counts are required, bilateral monitoring is essential.

A multicenter, randomized, controlled trial of Celsior for flush and hypothermic storage of cardiac allografts

BACKGROUND

A multicenter, randomized, controlled, open-label trial was conducted to evaluate the safety and efficacy of Celsior when used for flush and hypothermic storage of donor hearts before transplantation.

METHODS

Heart transplant recipients were randomized to one of two treatment groups in which donor hearts were flushed and stored in either Celsior or conventional preservation solution(s) (control). Study subjects were followed for 30 days after transplantation.

RESULTS

A total of 131 heart transplant recipients were enrolled (Celsior, n = 64; control, n = 67). The treatment groups were evenly distributed in donor and recipient base line characteristics. Graft loss rate was lower in the Celsior group on day 7 (3% versus 9%) and on day 30 (6% versus 13%), but the difference was not statistically significant based on 95% confidence interval analysis. No significant difference was measured between the Celsior and control groups in 7-day patient survival (97% versus 94%) and the proportion of patients with one or more adverse events (Celsior, 88%; control 87%) or serious adverse events (Celsior, 38%; control, 46%). Significantly fewer patients in the Celsior group developed at least one cardiac-related serious adverse event (13% versus 25%).

CONCLUSIONS

Celsior was demonstrated to be as safe and effective as conventional solutions for flush and cold storage of cardiac allografts before transplantation.

Cardiac transplantation: the University of Florida experience

Heart transplantation offered satisfactory outcomes in carefully selected patients with end stage congestive heart failure treated at our institution from 1990-1996. At the University of Florida, our survival rates involving 196 heart transplants were 86%, 78% and 74%, respectively, at one, 3 and 5 years. This data compares favorably with international results. Our typical transplant recipient was a 50-60 year old caucasian male with ischemic cardiomyopathy. Based on this population and the severe shortage of donor hearts available, aggressive attempts must continue to identify patients with ischemic cardiomyopathy that may benefit (i.e. adequate target vessel, viable myocardium) from high-risk coronary artery bypass surgery. Infection, rejection and graft vasculopathy continue to influence morbidity and mortality after transplantation. Continued efforts aimed at the development of improved immunosuppression as well as prevention and containment of coronary vasculopathy are needed if these results are to be significantly improved.

Lung transplantation after long-term mechanical ventilation : results and 1-year follow-up

BACKGROUND

Long-term mechanical ventilation is considered as a relative or absolute contraindication for lung transplantation by most centers. We report on the results of transplantation in nine patients requiring long-term mechanical ventilation at two lung transplant centers.

METHODS

The study group (group 1) consisted of nine patients receiving mechanical ventilation who underwent lung transplantation at either Duke University Medical Center or the University of Florida between 1992 and 1997. Patients in group 1 met the following criteria: they underwent exercise therapy with a physical therapist, and they were without panresistant bacterial airway colonization. The study patients that met these criteria spent at least 13 days receiving mechanical ventilation prior to transplantation. The control population (group 2; n = 65) consisted of all patients who underwent transplantation at either center in the calendar year 1997 who were ventilator independent. The 1-year survival rates in each group were calculated by the Kaplan-Meier method. The number of days required for extubation in each group were compared by the nonparametric Wilcoxon rank sum test. The FEV(1) value at 1 year was reported in each group.

RESULTS

The 1-year survival rates were 78% and 83% in group 1 and group 2, respectively. The mean number of days required until extubation were 41 days in group 1 and 9 days in group 2 (p < 0.01). The allograft function was comparable in the two groups at 1 year.

CONCLUSIONS

In a select population of ventilator-dependent patients, the 1-year survival rate is comparable to the standard lung transplant population. However, these ventilator-dependent patients require a significantly longer time until extubation than other transplant recipients.

Susceptibility of lung transplants to preformed donor-specific HLA antibodies as detected by flow cytometry

BACKGROUND

Preformed anti-HLA antibodies are known to have the potential to induce early graft damage in organ transplant recipients. However, in lung transplant recipients, little information exists about the significance of preformed antibodies directed to either class I or class II HLA antigens.

METHODS

A two-color flow cytometry cross-match was performed in 92 consecutive lung transplant recipients using serum obtained immediately before transplantation. The presence of preformed antibodies was correlated with the incidence of severe graft dysfunction manifested as pulmonary infiltrates and severe hypoxemia with onset in the first few hours after transplantation.

RESULTS

Six patients (6.5%) had low-level anti-donor IgG antibodies detected by flow cytometry, four against T and two against B lymphocytes. Three patients (50%) developed severe graft dysfunction with pulmonary infiltrates and hypoxemia. Two patients responded to treatment, but the third, who had an antibody highly specific for HLA-DR11, died at 48 hr after transplant. Results of histopathologic studies in this patient are consistent with hyperacute rejection and support a pathogenic role of these antibodies. In contrast, of 86 (93.5%) cases with a negative flow cytometry cross-match, only 4 (5%) had severe but reversible early graft dysfunction with pulmonary infiltrates and hypoxemia, attributed to ischemia-reperfusion injury (P<0.005).

CONCLUSIONS

Class II, and perhaps class I HLA antibodies at relatively low concentrations represent a risk factor for severe early pulmonary graft dysfunction, with the potential to progress to hyperacute rejection and death.

Superoxide Anion Generation, Superoxide Dismutase Activity, and Nitric Oxide Release in Human Internal Mammary Artery and Saphenous Vein Segments

BACKGROUND: Internal mammary artery (IMA) as conduit for a coronary artery bypass graft (CABG) stays patent longer and more often than saphenous vein (SV). However, the precise differences in the biology of IMA and SV are unclear. METHODS AND RESULTS: To examine inherent difference in superoxide anion, superoxide dismutase (SOD) and nitric oxide (NO) formation in IMA and SV as a basis for differences in patency rates, we measured these parameters in vascular segments of patients undergoing CABG. Superoxide anion generation was measured by lucigenin chemiluminescence and reduction of cytochrome c, SOD by inhibition of pyrogallol auto-oxidation, and No as nitrite/nitrate fluorometrically using 2-3-diaminonaphthalene as a probe. Generation of superoxide anion, SOD activity, and No formation were all greater in the IMA than in the SV segments (IMA:SV = 2.6:1, 2.9:1, 1, and 3.0:1, respectively, all P <.010. There was a positive correlation between superoxide anion generation and SOD activity (r = 0.65, P <.05; r = 0.70, P <.05 in IMA and SV, respectively) and NO release (r = 0.68, P <.05; r = 0.75, P <.03 in IMA and SV, respectively). Western blot analysis showed no differences in SOD and NO synthase protein expression in IMA and SV segment homogenates. To examine whether greater superoxide anion generation, SOD activity, and NO formation are unique to IMA, we studied pulmonary artery (PA) and pulmonary vein (PV) segments taken from patients undergoing lung resection. Superoxide anion generation, SOD activity, and NO formation were also found to be greater in PA than in PV segments. CONCLUSIONS: Inherently greater superoxide anion generation and subsequently increased formation of SOD and NO release in IMA (vs SV) may be a factor in the greater patency of the former as CABG conduit. Because both IMA and PA are exposed to pulsatile stretch and cary blood at higher pressure than the SV and PV, it is likely that these 2 factorsd account for the observed differences.

Factors influencing clinical outcomes after revascularization in the asymptomatic cardiac ischemia pilot (ACIP). ACIP Study Group

BACKGROUND AND AIM

The Asymptomatic Cardiac Ischemia Pilot is the first randomized trial where revascularization involved choice of either coronary bypass or angioplasty used in an early or a delayed symptom-driven approach. One-year outcomes were favorable (reduced recurrent ischemia and adverse outcomes) for an early revascularization strategy (within 4 weeks), compared with an early medical strategy when revascularization was delayed until symptom-driven. This ancillary study examined variables influencing outcomes after these 2 revascularization approaches (early vs. delayed until symptom-driven).

METHODS

Participants were clinically stable coronary disease patients with stress-induced and daily life ischemia who underwent revascularization. Characteristics associated with clinical outcomes occurring within the year following revascularization were examined using Cox regression analysis.

RESULTS

A total of 262 patients received revascularization; 170 in the early approach and 92 in the delayed symptom-driven approach. Thirty-three patients had adverse outcomes (death, nonfatal myocardial infarction, or repeat revascularization) during 1-year follow-up. The most important independent predictor of improved outcome during the follow-up year was attempted revascularization of > or = 66% of vessels with significant stenosis for the early (risk ratio [RR] 0.25, 95% confidence interval [CI] 0.09-0.67) and the delayed (RR 0.21, CI 0.08-0.58) approaches. Factors such as age, stress test results, and coronary angiographic findings did not predict clinical outcome.

CONCLUSIONS

Our findings are important in the planning of a large trial with longer follow-up.

Aortic valve endocarditis in an acutely rejecting orthotopic heart transplant recipient

Infective endocarditis is an infrequent but serious complication in heart transplant recipients. We report successful treatment for this serious complication.

Experimental and clinical allogeneic heart transplant rejection: correlations between histology and immune reactivity detected by cytokine messenger RNA

BACKGROUND

Cytokines produced by host cells infiltrating allogeneic transplants are critical determinants of graft rejection but information on cytokine production during graft rejection remains limited. No reported study on cytokine profiles has compared experimental allograft rejection induced by withdrawal of cyclosporine with clinical transplant rejection that occurs in the presence of therapeutic levels of cyclosporine.

METHODS

Functional activities of allograft-infiltrating host cells in sequential endomyocardial biopsies obtained before, during, and after acute heart transplant rejection were determined with the use of the reverse transcriptase-polymerase chain reaction to detect cytokine messenger RNA. These results were correlated with histologic findings in both an experimental canine model of heart transplant and rejection and in clinical human heart transplant recipients.

RESULTS

When experimental rejection was induced by withdrawal of immunosuppression, rejection was characterized by the presence of mRNA encoding CD4, CD8, interleukin-2 (but not interleukin-4), interleukin-2 receptor, and tumor necrosis factor-beta. These findings are consistent with a classic T-helper, T-cytotoxic cell-mediated response. However, the cytokine profile of human, clinical heart transplant rejection occurring in the presence of therapeutic levels of immunosuppression differed strikingly. In clinical rejection in human beings, histologic evidence of rejection was not associated with detectable interleukin-2 or interleukin-2 receptor mRNA.

CONCLUSIONS

Human, clinical heart rejection can occur in the absence of locally produced interleukin-2; the degree of immunosuppression achieved with cyclosporine A may explain the different results obtained in the canine withdrawal model versus human clinical allograft rejection.

Effect of ventilation on acid-base balance and oxygenation in low blood-flow states

OBJECTIVES

To investigate how minute ventilation affects the partial pressure of end-tidal CO2 and arterial and mixed venous pH, PCO2, PO2, and the concentration of bicarbonate during low blood-flow states. We tested the null hypothesis that acid-base conditions during low rates of blood flow are not significantly different when minute ventilation is doubled or halved.

DESIGN

Prospective, experimental, animal study.

SETTING

University hospital laboratory.

SUBJECTS

Domestic swine.

INTERVENTIONS

We studied ten anesthetized and mechanically ventilated swine (weight, 43 to 102 kg) in a new model of controlled systemic and pulmonary blood flow in which each animal was maintained on ventricular assist devices. After electrical induction of ventricular fibrillation, ventricular assist device blood flow was decreased in steps. At each decrease, control minute ventilation, two times the control minute ventilation (hyperventilation), and one-half the control minute ventilation (hypoventilation) were administered; each ventilatory change was maintained for 6 mins.

MEASUREMENTS AND MAIN RESULTS

Aortic, pulmonary arterial and central venous pressures, ventricular assist device blood flow, and end-tidal CO2 were recorded continuously. Acid-base conditions were studied at three different mean blood flow rates: 49%, 30%, and 12% of baseline prearrest cardiac index. Arterial pH and PaO2 and mixed venous pH varied directly (p < .003) with minute ventilation, while PaCO2 and mixed venous PCO2, and end-tidal CO2 varied inversely (p < .0001) with minute ventilation. Mixed venous PO2 was not significantly related to minute ventilation (p = .6). PaCO2 and arterial bicarbonate; mixed venous pH, mixed venous PO2, and mixed venous bicarbonate, and end-tidal CO2 varied directly (p < .001) with blood flow, while mixed venous PCO2 varied inversely with blood flow (p < .05). Arterial pH was not significantly related to blood flow (p = .3). When minute ventilation changed from hyperventilation to hypoventilation at a mean blood flow rate of 49%, mean arterial pH decreased 0.22 +/- 0.06 (p < .05), mean PaCO2 increased 28 +/- 6 torr (3.7 +/- 0.8 kPa) (p < .05), and mean PaO2 decreased 99 +/- 77 torr (13.2 +/- 10 kPa); mean mixed venous pH decreased 0.11 +/- 0.02, mean mixed venous PCO2 increased 16 +/- 2.2 torr (2.1 +/- 0.3 kPa) (p < .05), and mean mixed venous PO2 did not change; mean end-tidal CO2 increased 18 +/- 2 torr (2.4 +/- 0.3 kPa) (p < .05). The effect of changes in minute ventilation on blood gases and end-tidal CO2 was similar for mean blood flow rates of 30% and 12% of baseline cardiac index.

CONCLUSIONS

During low rates of blood flow similar to those rates found in shock and cardiopulmonary resuscitation, alterations in minute ventilation significantly influenced end-tidal CO2 and both arterial and mixed venous pH and PCO2. These findings may have clinical importance in improving the treatment of shock and cardiac arrest.

Isolation and maintenance of human pulmonary artery endothelial cells in culture isolated from transplant donors

Even though endothelial cells from different locations have similarities, there are potential morphological and functional differences between cells from different vascular regions, as well as between species. Our laboratory is interested in studying the molecular regulation of vasoactive substances in pulmonary vasculature. Therefore, we have developed reproducible methodology to isolate and maintain cultures of human pulmonary artery endothelial cells. The major innovation has been the employment of sections of pulmonary artery from heart transplant donors, from which endothelial cells are isolated. Cell monolayers were identified as endothelial cells by phase-contrast microscopy. Representative dishes of cells were further characterized by indirect immunofluorescent staining for factor VIII antigen, uptake of acetylated low-density lipoprotein, and electron microscopy. These cells were also evaluated for the expression of endothelin-1 (ET-1), a vasoactive 21-amino acid peptide derived from endothelial cells. The cells expressed ET-1 peptide and mRNA as determined by radioimmunoassay and Northern analysis, respectively. We also demonstrated that these cells are useful in transient transfection experiments for potential evaluation of promoter elements. The availability and relevance of these cells provide an important investigative tool for studies on human pulmonary vascular disease.

End-tidal carbon dioxide during extremely low cardiac output

STUDY OBJECTIVE

A number of studies have shown that expired CO2 concentration is closely related to cardiac output, but that cardiac output was not controlled as an independent variable. In addition, the partial pressure of end-tidal CO2 (PETCO2) during extremely low cardiac output has not been reported. The objective of the present study was to measure PETCO2 during well-controlled, very low blood flow rates under conditions of constant minute ventilation.

DESIGN

Ten anesthetized, intubated, and mechanically ventilated swine (weight, 43 to 102 kg) were placed on two ventricular assist devices in order to control cardiac output. Minute ventilation was measured and kept constant. Ventricular assist device output (measured with an ultrasonic flow probe); PETCO2; and aortic, pulmonary artery, and central venous pressures were recorded continuously.

INTERVENTIONS

After electrical induction of ventricular fibrillation, pump output was decreased in steps.

MEASUREMENTS AND MAIN RESULTS

Cardiac index ranged from 0 to 5,371 mL/min/m2; 59% of PETCO2 measurements were made at cardiac indexes of less than 1,313 mL/min/m2 (30 mL/min/kg). The relationship of PETCO2 levels to cardiac index was determined with linear regression analysis; P < .05 was statistically significant. PETCO2 correlated significantly with cardiac index (P < .0001). The best-fit line by least-squares analysis produced the equation: PETCO2 = 4.98 + 0.012 [cardiac index] (r2 = .82).

CONCLUSION

Under conditions of constant minute ventilation, PETCO2 correlated closely with cardiac index over a large range of blood flow rates, including extremely low rates.

Basis for the selective reduction of pulmonary vascular resistance in humans during infusion of adenosine

The objective of this study was to demonstrate the basis for the selective reduction of pulmonary vascular resistance by intravenous infusion of adenosine. Secondary objectives of the study were to determine the rate of central infusion of adenosine at which the nucleoside appears in the systemic circulation and to relate this to hemodynamic events. Plasma concentrations of adenosine in the right and left atria were measured during peripheral (5 patients) and central (12 patients) infusions of adenosine in adults with normal pulmonary arterial pressures undergoing coronary artery bypass surgery. The hemodynamic effects of central (right ventricle) infusion of adenosine were also examined. The extraction of adenosine across the pulmonary vascular bed was found to be 73.6 +/- 4.8%. The mean maximal decrease in pulmonary vascular resistance index, 48.8 +/- 9.6%, occurred at an adenosine infusion rate of 30 micrograms.kg-1.min-1, whereas the systemic vascular resistance index remained unchanged. Thus, adenosine, administered centrally in anesthetized patients with normal pulmonary vascular resistances, selectively lower pulmonary vascular resistance. The basis for this selective effect is the substantial extraction of adenosine during passage through the pulmonary vascular bed.

Exercise-induced hypoxemia in heart transplant recipients

OBJECTIVES

The purpose of this study was to determine whether heart transplantation has an adverse effect on pulmonary diffusion and to investigate the potentially deleterious effects of impaired pulmonary diffusion on arterial blood gas dynamics during exercise in heart transplant recipients.

BACKGROUND

Abnormal pulmonary diffusing capacity is reported in patients after orthotopic heart transplantation. Abnormal diffusion may be caused by cyclosporine or by the persistence of preexisting conditions known to adversely affect diffusion, such as congestive heart failure and chronic obstructive pulmonary disease.

METHODS

Eleven patients (mean age 50 +/- 14 years) performed pulmonary function tests 3 +/- 1 months before and 18 +/- 12 (mean +/- SD) months after heart transplantation. Transplant patients were assigned to groups with diffusion > 70% (n = 5) or diffusion < 70% of predicted values (n = 5). The control group and both subsets of patients performed 10 min of cycle exercise at 40% and 70% of peak power output. Arterial blood gases were drawn every 30 s during the 1st 5 min and at 6, 8 and 10 min.

RESULTS

Significant improvements in forced vital capacity (17.4%), forced expiratory volume in 1 s (11.7%) and diffusion capacity (6.6%) occurred in the patients; however, posttransplantation vital capacity, forced expiratory volume and diffusion were lower (p < or = 0.05) compared with values in 11 matched control subjects. Changes in blood gases were similar among groups at 40% of peak power output. At 70% of peak power output, arterial blood gases and pH were significantly (p < or = 0.05) lower in transplant patients with low diffusion (arterial oxygen pressure 15 to 38 mm Hg below baseline) than in patients with normal diffusion and control subjects. Cardiac index did not differ (p > or = 0.05) between transplant patients with normal and low diffusion at rest or during exercise. Posttransplantation mean pulmonary artery pressure was significantly related to exercise-induced hypoxemia (r = 0.71; p = 0.03).

CONCLUSIONS

Abnormal pulmonary diffusion observed in patients before heart transplantation persists after transplantation with or without restrictive or obstructive ventilatory defects. Heart transplant recipients experience exercise-induced hypoxemia when diffusion at rest is < 70% of predicted. Our data also suggest that abnormal pulmonary gas exchange possibly contributes to diminished peak oxygen consumption in some heart transplant recipients; however, direct testing of this hypothesis was beyond the scope of the present study. This possibility needs to be investigated further.

Blood gas dynamics at the onset of exercise in heart transplant recipients

One hypothesis to explain the rapid neural component of exercise hyperpnea contends that afferent stimuli originating in the ventricles of the heart act reflexly on the respiratory center at the onset of exercise, ie, "cardiodynamic hyperpnea." Orthotopic cardiac transplantation (Tx) results in the loss of afferent information from the ventricles. Thus, Tx possibly results in transient hypercapnia and hypoxemia in deafferented heart transplant recipients (HTR) at the onset of exercise due to hypoventilation. To examine the cardiodynamic hypothesis, we collected serial arterial blood gas (ABG) samples during both the transient and the steady-state responses to moderate cycle exercise in 5 HTRs (55 +/- 7 years) 14 +/- 7 months post-Tx and 5 control subjects matched with respect to gender, age, and body composition. Forced vital capacity, forced expiratory volume in 1 s, total lung capacity, and diffusion capacity did not differ (p > or = 0.05) between groups. Resting arterial PO2, PCO2, and pH did not differ between groups (p > or = 0.05). The ABGs were drawn every 30 s during the first 5 min and at 6, 8, and 10 min of constant load square wave cycle exercise at 40 percent of the peak power output (watts). Absolute and relative changes in arterial PO2, PCO2, and pH were similar (p > or = 0.05) between HTR and the control group at all measurement periods during exercise. Heart rate (%HRmax reserve), rating of perceived exertion, and reductions in plasma volume (% delta from baseline) did not differ between HTR and control during exercise at 40 percent of peak power output (p > or = 0.05). Our results demonstrate that there is no discernible abnormality in ABG dynamics during the transient response to exercise at 40 percent of peak power output in patients with known cardiac denervation. These data do not support the cardiodynamic hyperpnea hypothesis of ventilatory control in humans. The absence of hypercapnia in HTRs is further evidence for the existence of redundant mechanisms capable of stimulating exercise hyperpnea.

Abnormal neuroendocrine responses during exercise in heart transplant recipients

BACKGROUND

Osmotic and neural factors stimulate neuroendocrine activity during exercise. In contrast to excitatory mechanisms, afferent information from cardiac mechanoreceptors inhibits integrative centers in the hypothalamus and medula oblongata, which serves to buffer neuroendocrine activity. Orthotopic cardiac transplantation results in the loss of afferent information from cardiac mechanoreceptors. Thus, transplantation possibly results in exaggerated neuroendocrine responses when patients are physically active.

METHODS AND RESULTS

We measured the neuroendocrine response to moderate and strenuous exercise performed at the same relative intensity in 11 heart transplant recipients (50 +/- 14 years old) 18 +/- 12 months after transplantation and 11 control subjects matched with respect to sex, age, and body size. Plasma levels of norepinephrine, vasopressin, renin activity, atrial natriuretic peptide, angiotensin II, and aldosterone were measured at rest, during a maximal graded exercise test, and during submaximal exercise at 40% and 70% of peak power output on a cycle ergometer (W). Plasma renin activity and atrial natriuretic peptide were elevated at rest in heart transplant recipients (p < or = 0.05). Heart rate (%HRmax reserve), rating of perceived exertion, and reductions in plasma volume (% delta from rest) at the conclusion of the three exercise conditions did not differ between heart transplant recipients and control (p > or = 0.05). Relative changes in neuroendocrine hormones were similar (p > or = 0.05) in heart transplant recipients and control during exercise at 40% of peak power output. Relative changes in plasma norepinephrine, vasopressin, atrial natriuretic peptide, and plasma renin activity were greater (p < or = 0.05) in heart transplant recipients during exercise at 70% of peak power output and the graded exercise test.

CONCLUSIONS

We interpret these data as a possible indication of ablation of cardiac mechanoreceptor afferents and unopposed neuroendocrine stimulation in heart transplant recipients. Furthermore, chronic neuroendocrine hyperactivity is likely in ambulatory heart transplant recipients. Although cyclosporine nephrotoxicity is implicated in the development of hypertension, our data suggest that chronic neuroendocrine hyperactivity, which alters renal volume regulation, also contributes to the incidence and severity of hypertension in heart transplant recipients.

Adenosine-induced atrioventricular block: a rapid and reliable method to assess surgical and radiofrequency catheter ablation of accessory atrioventricular pathways

Adenosine has been shown to inhibit anterograde and retrograde conduction through the atrioventricular (AV) node while having little or no effect on accessory pathway conduction. Its rapid onset of action and short half-life make it particularly suitable for repetitive measurements. In this study, the utility of adenosine was tested in assessing completeness of accessory pathway ablation. Sixteen patients with an accessory pathway were studied (eight surgical ablations, eight catheter ablations with radiofrequency energy). Before ablation, no accessory pathway was sensitive to adenosine. Twelve patients with pre-excitation showed high grade AV node block with maximal pre-excitation on the administration of adenosine during atrial pacing. Four patients with a concealed accessory pathway demonstrated high grade AV block without evidence of latent anterograde accessory pathway conduction. Preablation ventriculoatrial (VA) block was not observed in any of the 16 patients in response to adenosine during ventricular pacing. Immediately after accessory pathway ablation, all patients developed AV and VA block with the administration of adenosine during atrial and ventricular pacing, respectively. These findings were confirmed during follow-up study 1 week later. Atrioventricular block during atrial and ventricular pacing with adenosine affords a reliable and immediate assessment of successful pathway ablation.

Familial cardiac myxoma

The majority of cardiac myxomas occur sporadically as isolated lesions in the left atrium of middle-aged women. However, a "familial" form and a "syndrome" form of this lesion have been identified. The syndrome myxoma can present with pigmented skin lesions and peripheral or endocrine neoplasms. The familial and syndrome forms of cardiac myxomas can usually be distinguished from the sporadic form by the presentation at a younger age, the unusual location and multicentricity of the lesions, and the presence of rare pathological conditions. In addition, a higher rate of recurrent lesions is usually associated with the familial and syndrome forms of this disease. To date, 15 families with cardiac myxomas have been reported in the world's literature. Here we present 2 additional case reports.

Acute vascular rejection of the coronary arteries in human heart transplantation: pathology and correlations with immunosuppression and cytomegalovirus infection

Prior studies of vascular rejection in transplanted human hearts have stressed the importance of accelerated coronary arteriosclerosis (chronic vascular rejection). We, however, have had four patients with sudden onset of acute heart failure within 90 days of transplantation who have died without significant myocardial interstitial rejection or the concentric intimal thickening with dense collagen that is typical of chronic vascular rejection. In contrast, the coronary arteries in our patients had a prominent lymphocytic infiltrate, a loosely organized intimal thickening composed of smooth muscle cells, and extensive endothelial injury. We believe that these changes define acute vascular rejection of the coronary artery. In 14 transplanted hearts obtained consecutively, at autopsy or at a second transplant procedure, graft failure was caused by acute coronary vascular rejection in six cases and by chronic coronary vascular rejection in one case. The remaining seven patients showed no evidence of vascular rejection and died primarily of sepsis. Cytomegalovirus (CMV) disease was present in 6 of 7 patients with vascular rejection, of which 43% were CMV-negative recipients of hearts from CMV-positive donors. The adoption of a triple-drug protocol, in which azathioprine was added to cyclosporine and prednisone, reduced the incidence of acute vascular rejection from 27% to 8%. We conclude that acute coronary vascular rejection may be initially seen as global cardiac ischemia in the absence of significant interstitial myocardial rejection. Further, acute vascular rejection should be pathologically distinguished from chronic vascular rejection, although both are probably stages in the natural history of immune-mediated vascular injury.

Correction of reentrant atrioventricular tachycardia by surgical ablation of accessory pathways

Patients with reentrant atrioventricular (AV) tachycardia have an accessory connection in addition to the normal conduction pathway, AV node and His-Purkinje system. This pathway predisposes some patients to recurrent, disabling supraventricular tachyarrhythmias. Although it is found with other associated cardiac conditions, most patients are healthy with no underlying structural heart disease. Interest has developed in surgically dividing the accessory pathway in patients with arrhythmias poorly controlled with medications or at risk for potentially fatal tachyarrhythmias. Surgery is safe and effective and should be considered for patients with rapid AV conduction during atrial fibrillation, those refractory to pharmacologic therapy, and young patients who otherwise would require lifelong antiarrhythmic therapy. This report describes surgical correction of reentrant AV tachycardia in five patients ranging in age from six months to 23 years.

Emergency coronary artery bypass graft surgery for threatened acute myocardial infarction related to coronary artery catheterization

In 20 patients undergoing cardiac catheterization, usually involving balloon-catheter dilation or streptokinase infusion, catheter-induced coronary artery intimal damage resulted in severe chest pain, electrocardiographic evidence of obstruction or dissection of a major coronary artery. These patients were surgically revascularized within 8 hours after the onset of the acute chest pain syndrome. Our experience with pharmacological and catheter-related manipulations to improve coronary blood flow after the ischemic episode but before operation suggested that the additional time spent in the catheterization laboratory was worthwhile. The injured coronary artery was the left anterior descending in 10 patients, the right in 8, the left main in 1 patient, and an obtuse marginal branch of the circumflex in 1. The average number of grafts per patient was 2.5; only 6 patients had single bypass grafts. In 5 patients, intraaortic balloon pumping was used either preoperatively or postoperatively. Inotropic support was used postoperatively in 5 patients, and 7 patients received lidocaine for ventricular irritability. Abnormal elevation of the serum isoenzyme of creatine kinase (CK-MB) was seen in 8 patients, and new Q waves were noted in 4 patients; 3 of these 4 patients with new Q waves also had abnormal serum CK-MB levels. Global ejection fraction obtained by the equilibrium-gated blood pool scan postoperatively was 60 +/- 3%, which was similar to the 62 +/- 3% obtained from the contrast-determined ventriculogram done preoperatively prior to the catheter-related injury. There were no early or late deaths, but morbidity was much higher in the group who had emergency coronary artery bypass grafting (CABG) compared with those who had elective CABG.(ABSTRACT TRUNCATED AT 250 WORDS)