Brain death alters cardiopulmonary hemodynamics and impairs right ventricular power reserve against an elevation of pulmonary vascular resistance

Management of Variations in Blood Pressure during Care of Organ Donors

The organ procurement coordinator commonly must correct and maintain the arterial blood pressure during donor care. This article reviews considerations in the accurate measurement of the blood pressure, causes of hypertension and hypotension, and desirable standards to use in order to provide adequate organ perfusion. Recommendations are presented for treatment of hypotension in a titrated response of intravenous fluids, inotropic support, and vasopressor infusion to maintain the mean arterial pressure above 65 mm Hg. Collaborative interaction between the coordinator and physician consultant remains important throughout management of blood pressure changes during donor care.

Influencing factors for early acute cerebrovascular accidents in patients with stroke history following off-pump coronary artery bypass grafting

PURPOSE

To analyse risk factors for early acute cerebrovascular accidents following off-pump coronary artery bypass grafting (OPCAB) in patients with stroke history, and to propose preventive measures to reduce the incidence of these events.

METHODS

A total of 468 patients with a history of stroke underwent OPCAB surgery in Beijing Anzhen Hospital of China from January 2010 to September 2012. They were retrospectively divided into two groups according to the occurrence of early acute cerebrovascular accidents within 48 hours following OPCAB. Multivariate logistic regression analysis was used to find risk or protective factors for early acute cerebrovascular accidents following the OPCAB.

RESULTS

Fifty-two patients (11.1%) suffered from early acute cerebrovascular accidents in 468 patients, including 39 cases of cerebral infarction, two cases of cerebral haemorrhage, 11 cases of transient ischaemic attack (TIA). There were significant differences between the two groups in preoperative left ventricular ejection fraction ≤ 35%, severe bilateral carotid artery stenosis, poorly controlled hypertension, intraoperative application of Enclose® II proximal anastomotic device, postoperative acute myocardial infarction, atrial fibrillation, hypotension, ventilation time > 48h, ICU duration >48h and mortality. Multivariate logistic regression analysis showed that preoperative severe bilateral carotid stenosis (OR=6.378, 95%CI: 2.278-20.987) and preoperative left ventricular ejection fraction ≤ 35% (OR=2.737, 95%CI: 1.267-6.389), postoperative acute myocardial infarction (OR=3.644, 95%CI: 1.928-6.876), postoperative atrial fibrillation (OR=3.104, 95%CI:1.135∼8.016) and postoperative hypotension (OR=4.173, 95%CI: 1.836∼9.701) were independent risk factors for early acute cerebrovascular accidents in patients with a history of stroke following OPCAB procedures, while intraoperative application of Enclose® II proximal anastomotic device was protective factor (OR=0.556, 95%CI: 0.337-0.925).

CONCLUSIONS

This study indicated that patients with severe bilateral carotid stenosis, the left ventricular ejection fraction ≤35%, the postoperative acute myocardial infarction, postoperative atrial fibrillation and postoperative hypotension were more likely to suffer from early acute cerebrovascular accidents when they received OPCAB. Application of Enclose® II proximal anastomotic device may decrease the incidence of early acute cerebrovascular accidents during OPCAB.

A sphingosine 1-phosphate 1 receptor agonist modulates brain death-induced neurogenic pulmonary injury

Lung transplantation remains the only viable therapy for patients with end-stage lung disease. However, the full utilization of this strategy is severely compromised by a lack of donor lung availability. The vast majority of donor lungs available for transplantation are from individuals after brain death (BD). Unfortunately, the early autonomic storm that accompanies BD often results in neurogenic pulmonary edema (NPE), producing varying degrees of lung injury or leading to primary graft dysfunction after transplantation. We demonstrated that sphingosine 1-phosphate (S1P)/analogues, which are major barrier-enhancing agents, reduce vascular permeability via the S1P1 receptor, S1PR1. Because primary lung graft dysfunction is induced by lung vascular endothelial cell barrier dysfunction, we hypothesized that the S1PR1 agonist, SEW-2871, may attenuate NPE when administered to the donor shortly after BD. Significant lung injury was observed after BD, with increases of approximately 60% in bronchoalveolar lavage (BAL) total protein, cell counts, and lung tissue wet/dry (W/D) weight ratios. In contrast, rats receiving SEW-2871 (0.1 mg/kg) 15 minutes after BD and assessed after 4 hours exhibited significant lung protection (∼ 50% reduction, P = 0.01), as reflected by reduced BAL protein/albumin, cytokines, cellularity, and lung tissue wet/dry weight ratio. Microarray analysis at 4 hours revealed a global impact of both BD and SEW on lung gene expression, with a differential gene expression of enriched immune-response/inflammation pathways across all groups. Overall, SEW served to attenuate the BD-mediated up-regulation of gene expression. Two potential biomarkers, TNF and chemokine CC motif receptor-like 2, exhibited gene array dysregulation. We conclude that SEW-2871 significantly attenuates BD-induced lung injury, and may serve as a potential candidate to improve human donor availability.

Early events in kidney donation: progression of endothelial activation, oxidative stress and tubular injury after brain death

Cerebral injury leading to brain death (BD) causes major physiologic derangements in potential organ donors, which may result in vascular-endothelial activation and affect posttransplant graft function. We investigated the kinetic of pro-coagulatory and pro-inflammatory endothelial activation and the subsequent oxidative stress and renal tubular injury, early after BD declaration. BD was induced by slowly inflating a balloon-catheter inserted in the extradural space over a period of 30 min. Rats (n = 30) were sacrificed 0.5, 1, 2 or 4 h after BD-induction and compared with sham-controls. This study demonstrates immediate pro-coagulatory and pro-inflammatory activation of vascular endothelium after BD in kidney donor rats, proportional with the duration of BD. E- and P-Selectins, Aalpha/Bbeta-fibrinogen mRNA were abruptly and progressively up-regulated from 0.5 h BD onwards; P-Selectin membrane protein expression was increased; fibrinogen was primarily visualized in the peritubular capillaries. Plasma von Willebrand factor was significantly higher after 2 h and 4 h BD. Urine heart-fatty-acid-binding-protein and N-acetyl-glucosaminidase, used as new specific and sensitive markers of proximal and distal tubular damage, were found significantly increased after 0.5 h, with a maximum at 4 h. Unexpectedly, oxidative stress was detectable only late, after the installation of tubular injury, suggesting only a secondary role for hypoxia in triggering these injuries.

Distinct effects of surgical denervation on hepatic perfusion, bowel ischemia, and oxidative stress in brain dead and living donor porcine models

The liver function and perfusion following brain death is mainly influenced by the sympathetic nerves and hormones. We examined the specific influence of surgical liver denervation on systemic and hepatic perfusion parameters, bowel ischemia and oxidative stress in hemodynamically stable BD and control (living donor [LD]) pigs. Brain death was induced in 8 pigs via saline infusion into the balloon of an epidural Tieman-catheter (1 mL/15 minutes) and compared to the control group (n = 6) over 4 hours. At 2 hours postoperatively, complete liver denervation was initiated. We analyzed systemic cardiocirculatory parameters (mean arterial pressure, aortic flow, bowel ischemia (endotoxin, and endotoxin-neutralizing capacity) and oxidative stress (total glutathione in erythrocytes [tGSH(E)]) and compared them to local/hepatic perfusion parameters (hepatic artery and portal venous flow, liver blood flow index, and microperfusion), local bowel ischemia (intramucosal pH [pHi] of stomach [pHi(S)]/colon[pHi(C)]), and liver oxidative stress (glutathione [rGSH(L), GSSG(L)]). Following brain death, the parameters including mean arterial pressure, aortic flow, pHi, endotoxin, and tGSH(E) showed no significant changes at 2 hours. Portal venous flow and microperfusion were decreased significantly and hepatic arterial buffer response was ineffective. Hepatic oxidative stress was increased in BD animals (decrease rGSH(L), increase GSSG(L)). Surgical denervation/manipulation increased portal venous flow significantly, hepatic arterial buffer response became effective, and stomach pHi decreased (BD and LD groups). Hepatic oxidative stress was reduced in the BD group (increase rGSH(L)/GSSG(L); P < 0.001) while it was increased in the LD group (decrease rGSH(L)/GSSG(L); P < 0.001). In conclusion, denervation reduces hepatic oxidative stress in BD only in contrast to the LD. The reciprocal effect of denervation depends on the state of neural activation and postulates a potential benefit of surgical denervation before organ harvesting in brain death.

Transplantation using hearts from primary pulmonary hypertensive donors for recipients with a high pulmonary vascular resistance

BACKGROUND

Transplantation for patients with a high pulmonary vascular resistance (PVR) carries an increased risk of mortality and right heart failure following heart transplantation and continues to be a major problem. We evaluated the use of hearts from patients who underwent heart and lung transplantation for primary pulmonary hypertension (PPH) as part of a domino procedure because these hearts have hypertrophied right ventricles used to increased pulmonary pressures, but could have a compromised left ventricle or irreversible damage of the right ventricle.

METHODS

We reviewed 12 patients with PVR >4 Wood units who underwent orthotopic heart transplantation between 1989 and 1998 using hearts from donors with PPH as part of a domino procedure.

RESULTS

We studied 10 men and 2 women, mean age 42.9 years. Mean PVR was 5.3 (range, 4-9) Wood units. Mean ischemia time was 85.3 minutes, and mean donor age was 32 years. Actuarial survival was 75% at 1 year and 75% at 5 years. In the early post-operative period, 3 patients had temporary arrhythmias, 2 required permanent pacemaker implantation, 1 had atrial fibrillation, and 1 had ventricular tachycardia that required defibrillator implantation. At a mean follow-up of 7.8 years, 2 patients had developed asymptomatic transplant coronary disease (both at 8.5 years after transplantation), 1 moderate and 1 very mild; the rest had none. Mean left ventricular ejection fraction at latest follow-up was 70.1% (range, 63%-78%). Right ventricular function assessed clinically and by echocardiography was adequate in the short and long term.

CONCLUSIONS

Our results suggest that heart and lung recipients with PPH can provide useful donor hearts to patients with increased PVR and that these hearts function well in the intermediate and long term.

Extracorporeal Membrane Oxygenation is Superior to Right Ventricular Assist Device for Acute Right Ventricular Failure After Heart Transplantation

BACKGROUND

Acute right ventricular failure after heart transplantation is a life-threatening condition, and sometimes the use of mechanical circulatory support is inevitable. The aim of this retrospective study was to investigate the effectiveness of two different mechanical circulatory support systems for this indication.

METHODS

From 1984 to 2003, 28 heart transplant recipients exhibited right ventricular failure resistant to drug therapy. Right ventricular assist device (n = 15) or extracorporeal membrane oxygenation (n = 13) was implanted to support the failing heart.

RESULTS

Overall in-hospital survival was 43%. In the right ventricular assist device group, only 2 patients (13%) could be weaned from mechanical circulatory support compared with 10 patients (77%) in the extracorporeal membrane oxygenation group (p = 0.001). Retransplantation was necessary in 6 patients in the right ventricular assist device group and in 1 patient in the extracorporeal membrane oxygenation group (p = 0.049). There was no difference in patient survival between groups, but graft survival was significantly better in the extracorporeal membrane oxygenation group (p = 0.005).

CONCLUSIONS

In view of these results, extracorporeal membrane oxygenation seems to be the better option as mechanical circulatory support for right ventricular failure in heart transplantation.

EFFECT OF ACUTE BRAIN DEATH ON RELEASE OF ATRIUM AND B-TYPE NATRIURETIC PEPTIDES IN AN ANIMAL MODEL

INTRODUCTION

Atrium and B-type natriuretic peptides (ANP and BNP) and big endothelin (ET)-1 are markers for severity of heart failure and may be used in the quality assessment of donor hearts. Elevated cardiac troponins predict early graft failure after heart transplantation. This study evaluated the effects of acute brain death (BD) on the release of ANP, BNP, big ET-1, and cardiac troponins in an animal model.

MATERIALS AND METHODS

Pigs were randomized into a BD group (n=5) and a control group (n=5). In the first group, acute BD was induced, and anesthesia was stopped. In the control animals, a sham operation was performed, and anesthesia was continued. Parameters were measured at baseline and for 13 hours postoperatively.

RESULTS

After acute BD, there were significant hemodynamic changes. In the control group, the BNP level was higher than in the BD group and decreased over time (P =0.016). There was no significant change in BNP release in the BD group up to 13 hours (P =0.1). ANP release remained stable over time in the control group (P =0.35) but decreased in the BD group (P =0.043). The big ET-1 levels were not different between groups. Cardiac troponin I was elevated in the BD group 5 hours after BD (P< 0.05) but remained under 1.5 mg/L throughout the study.

CONCLUSION

Acute BD did not lead to an increase of BNP and ANP levels. Moreover, intact brain function seems to augment the release of natriuretic peptides from the myocardium. Further clinical evaluation of prognostic values of natriuretic peptides for the assessment of donor hearts is necessary. Cardiac troponins are a useful additional tool in the evaluation of donor hearts.

Mechanical support for the failing cardiac allograft: a single-center experience

BACKGROUND

Mechanical support for pre-transplant stabilization is established, but its use in peri-operative graft failure (PGF) has not been well documented. With liberal acceptance criteria being used to enlarge the donor pool, an increased incidence of graft failure might be expected. We evaluated the incidence and outcome of PGF at our institution.

METHODS

A retrospective review of 462 consecutive adult heart transplants performed between January 1993 and December 1999 revealed 20 cases of PGF. Donor-, surgery- and device-related variables were evaluated for association with operative mortality, survival and successful device weaning.

RESULTS

Transplant recipients included 17 men and 3 women, median age 56.5 years (20 to 66 years). PGF etiology included primary graft failure (n = 9); right heart failure (RHF) secondary to pulmonary hypertension, coagulopathy/intra-operative hemorrhage or sepsis (n = 9); and hyperacute rejection (n = 2). Device types included RVAD (n = 11), LVAD (n = 4), BIVAD (n = 3) and IABP (n = 2). The wean rate was 45%. Duration of device support ranged from 2 to 965 hours. Early ventricular recovery (within 96 hours) was associated with significantly better 30-day and 2-year survival. Weaned patients had an 88% 30-day and 67% 2-year survival, whereas the overall survival rate was 79% at 2 years (p = not significant).

CONCLUSIONS

Early ventricular recovery is an important predictor of successful weaning and survival. In view of the prohibitive mortality associated with PGF and the dismal prognosis with re-transplantation, we advocate aggressive use of mechanical assistance for PGF, with an acceptable survival benefit.

Long-term results of cardiac transplantation from live donors: the domino heart transplant

BACKGROUND

Hearts explanted from the recipients of heart-lung transplants provide a unique source of transplants from live donors. This article presents long-term results with this procedure at our center.

METHODS

We performed a retrospective chart review of domino transplantations performed in our institution between 1989 and 1998.

RESULTS

We analyzed 131 domino transplants (123 orthotopic, 8 heterotopic). Domino hearts were from patients with cystic fibrosis (69%), primary pulmonary hypertension (15%), and other diagnoses (16%). The mean recipient pulmonary vascular resistance (PVR) was 3.1 Wood units, 25% of patients having values >4 Wood units. Thirty-day mortality was 13%. The 1-, 5-, and 10-year graft survival was 75% (70% confidence interval [CI], 65-74), 70% (70% CI, 65-74), and 58% (70% CI, 52-64), respectively. Patients with PVR >4 Wood units had 1-year survival (76%; 70% CI, 69-84) similar to that of patients with PVR of < or =4 units (74%; 70% CI, 69-80). Recipients of hearts from patients with cystic fibrosis survived longer (5-year survival, 76%; 70% CI, 71-82) vs 65% for non-cystic fibrosis hearts (70% CI, 57-74) p = 0.09). One-year survival was decreased after transplantation of hearts from female donors (66%; 70% CI, 60-72)) compared with hearts from male donors (85%; 70% CI, 79-90); p = 0.06). Late deaths caused by coronary artery disease and malignancy were uncommon.

CONCLUSION

Although the rate of early mortality after domino transplantation was slightly higher than after cadaveric transplantation, we noted a remarkably low long-term attrition rate in recipients of domino grafts, up to 10 years. In addition, successful transplantation of patients with high PVR supports the hypothesis that heart-lung recipients may provide superior donor hearts for this patient group, many of whom traditional listing criteria would exclude.

Management of variations in blood pressure during care of organ donors

The organ procurement coordinator commonly must correct and maintain the arterial blood pressure during donor care. This article reviews considerations in the accurate measurement of the blood pressure, causes of hypertension and hypotension, and desirable standards to use in order to provide adequate organ perfusion. Recommendations are presented for treatment of hypotension in a titrated response of intravenous fluids, inotropic support, and vasopressor infusion to maintain the mean arterial pressure above 65 mm Hg. Collaborative interaction between the coordinator and physician consultant remains important throughout management of blood pressure changes during donor care.

ICAM-1 affects reperfusion injury and graft function after cardiac transplantation

BACKGROUND

The effects of increased expression of intercellular adhesion molecule (ICAM-1), an important mediator of neutrophil-mediated reperfusion injury (RI), were assessed in donor cardiac allografts in a heterotopic rat transplantation model.

METHODS

At -24 h, PVG donors were untreated (n = 35) or treated (n = 37) with lipopolysaccharide (LPS, 5 mg/kg ip). Hearts were procured at 0 h, stored at 4 degrees C for 45 min, and grafted heterotopically into ACI recipients pretreated with vehicle or anti-ICAM-1 (1A29) mAb. Intracardiac balloons (n = 8 per group) were used to measure allograft left ventricular function (dP/dt) prior to harvest and following reperfusion. RI was assessed at 6, 12, and 24 h by myeloperoxidase (MPO) levels, percentage wet weight (%w/w), and percentage contraction band necrosis (%CBN).

RESULTS

At 12 h, LPS-pretreated grafts showed increased ICAM-1 expression by Northern blot (n = 3) and immunohistochemistry (n = 3) and significantly increased MPO (0.33 +/- 0.2 U/mg vs 0.05 +/- 0.04 U/mg at 12 h), %w/w (81.7 +/- 1.8% vs 79.2 +/- 0.7% at 12 h), and %CBN (15.2 +/- 1. 9% vs 11.4 +/- 2.0% at 24 h). LPS pretreatment had no effect on graft function at early time points (baseline to 2 h) but led to depressed dP/dt at later time points with trends toward significance at 12 h (2101 +/- 1653 mmHg/s vs 173 +/- 201 mmHg/s, P = 0.06, ANOVA). Recipient 1A29 treatment (n = 6 per group) reversed the effects of LPS pretreatment in all three RI parameters and significantly improved functional recovery.

CONCLUSIONS

Alteration of cardiac graft phenotype to that likely seen in clinical organ donors leads to increased delayed-onset myocardial RI following transplantation in this model. The blockade of this increased RI following 1A29 mAb treatment supports a central role for ICAM-1 in this process.

Right ventricular dysfunction after cardiac transplantation: primarily related to status of donor heart

BACKGROUND

It is unclear whether right ventricular dysfunction after transplantation is due to donor brain death-related myocardial injury or recipient pulmonary hypertension.

METHODS

A canine donor model of brain death and a monocrotaline pyrrole-induced chronic pulmonary hypertension recipient model were established, and used for 30 orthotopic bicaval cardiac transplantations divided into three groups: Controls (group A, normal donor/recipient), group B (brain-dead donors/normal recipient), and group C (normal donor/recipients with pulmonary hypertension). Right ventricular function was measured before transplant and brain death, 4 hours after brain death, and after transplant (1 hour off bypass) by load-independent means plotting stroke work versus end-diastolic volume during caval occlusion. Right ventricular total power and pulmonary vascular impedance were determined by Fourier analysis.

RESULTS

In comparison to the control group right ventricular preload-recruitable stroke work and total power decreased significantly after brain death and transplant in group B (from 22.7 x 10(3) erg (+/-1.2) at baseline to 15.6 x 10(3) (+/-0.9) after brain death and to 11.3 x 10(3) (+/-0.9) after transplant). In group C there was a significant increase in pulmonary artery pressure, impedance, right ventricular preload-recruitable stroke work, total power after transplant.

CONCLUSIONS

Normal donor hearts adapt acutely to the recipient's elevated pulmonary vascular resistance by increasing right ventricular power output and contractility. Brain death caused significant right ventricular dysfunction and power loss, which further deteriorated after graft preservation and transplantation. The effects of donor brain death on myocardial function contribute to right ventricular dysfunction after cardiac transplantation.

Pulmonary vascular impedance and recipient chronic pulmonary hypertension following cardiac transplantation

STUDY OBJECTIVES

Recipient chronic pulmonary hypertension (CPH), secondary to long-standing congestive heart failure, represents a significant risk factor for right ventricular (RV) dysfunction following orthotopic cardiac transplantation (TX). This study was designed to characterize the changes occurring in pulmonary hemodynamics, pre-TX and post-TX, using Fourier analysis, a canine model of bicaval TX, and monocrotaline pyrrole (MCTP)-induced recipient CPH.

DESIGN

Prospective, controlled study.

SETTING

Experimental laboratory.

PARTICIPANTS

Twenty adult male mongrel dogs (23 to 26 kg).

INTERVENTIONS

Recipients underwent pulmonary artery injection of 3 mg/kg MCTP 4 months pre-TX. On the day of TX, donor hearts were instrumented with an ultrasonic flow probe and micromanometers. Harmonic derivation of functional data was achieved with Fourier analysis.

MEASUREMENTS AND RESULTS

At the time of TX, significant increases were observed in the mean pulmonary artery pressure and pulmonary vascular resistance of recipient animals in comparison to donors, which were further significantly increased following the termination of cardiopulmonary bypass. Significant increases were also observed in the input resistance, characteristic impedance, and RV hydraulic power post-TX compared to pre-TX, and occurred in association with a significant decrease in the transpulmonary efficiency.

CONCLUSIONS

In the setting of MCTP-induced recipient CPH donor hearts were exposed to significant alterations in cardiopulmonary hemodynamics following bicaval TX. Pulmonary blood flow is maintained by a significantly higher energy expenditure by the RV, but at a lower level of efficiency. This experimental model may provide a useful means by which to evaluate therapeutic options to better manage cardiopulmonary hemodynamics in order to prevent RV failure following TX in the setting of recipient CPH.