Long-term survivors of pediatric heart transplantation: a multicenter report of sixty-eight children who have survived longer than five years

OBJECTIVE

Short-term survival after pediatric heart transplantation is now excellent, but ultimately the efficacy of this procedure will depend on duration and quality of survival. We sought to evaluate the clinical course of long-term survivors of heart transplantation in childhood.

METHODS

Patients who had undergone heart transplantation at the university hospitals of Stanford, Columbia, and Pittsburgh between 1975 and 1989 and survived longer than 5 years from transplantation were identified and their clinical courses retrospectively reviewed.

RESULTS

Sixty eight children have survived more than 5 years from transplantation, and 60 (88%) are currently alive with a median follow-up of 6.8 years (5 to 17.9 years). Thirteen have survived more than 10 years from transplantation. Renal dysfunction caused by immunosuppressive agents was common, and two patients required late renal transplantation. Lymphoproliferative disease or other neoplasm occurred in 12 patients, but none resulted in death. Coronary artery disease was diagnosed in 13 patients (19%), leading to retransplantation in eight. Death after 5 years was related to acute or chronic rejection in 5 of 8 cases. Two of the deaths were directly related to noncompliance with immunosuppressive medication. All survivors are in New York Heart Association class 1.

CONCLUSIONS

Long-term survival with good quality of life can be achieved after heart transplantation in childhood, though complications of immunosuppression remain common. Posttransplantation coronary artery disease is emerging as the main factor limiting long term graft and patient survival.

Heart reduction surgery: an analysis of the impact on cardiac function

OBJECTIVES

Reports of improved ejection fraction, coupled with decreased filling pressures, have prompted a number of centers to begin evaluating the efficacy of heart reduction surgery to ameliorate symptoms of heart failure. However, the impact of this operation on cardiac mechanics is unknown. We applied a multiple compartment elastance model to simulate the effects of excising cardiac mass on heart function.

METHODS

The left ventricle was divided into two functional compartments to simulate excision of part of the wall. At multiple increments of mass reduction, the resulting end-systolic elastance, ejection fraction, stroke volume, end-diastolic pressure and volume, and diastolic stiffness were determined.

RESULTS

Changes in systolic function were accompanied by offsetting changes in diastolic function; consequently, overall pump function (the Frank-Starling Relationship) was found to be depressed. The geometric rearrangement associated with this operation leads to a reduction in wall stress for a given level of pressure generation, thus implying an increase in the efficiency with which wall stress is transduced into intraventricular pressure.

CONCLUSIONS

Overall pump function is depressed in the short run after heart reduction surgery. However, on the basis of theoretic arguments, heart reduction surgery may have long-term beneficial implications. Importantly, this analysis revealed that changes in parameters of ventricular function have different implications during heart reduction surgery than when such changes are observed with inotropism caused by acute pharmacologic therapy.

Retrograde cardioplegia preserves myocardial function after induced coronary air embolism

Coronary air embolism is a potential complication of cardiopulmonary bypass. We compared left ventricular function before and after the administration of antegrade or retrograde cardioplegic solution in a porcine model of coronary air embolism. Nineteen pigs were placed on cardiopulmonary bypass support and cooled to 32 degrees C. The heart was initially arrested with antegrade cold blood cardioplegic solution. The aortic crossclamp was released at 30 minutes and 0.02 cc/kg body weight of air was injected into the left anterior descending artery distal to the first diagonal branch. After 5 minutes the aorta was reclamped and the animals treated with 15 ml/kg body weight of 1:4 blood cardioplegic solution delivered by the antegrade (n = 6) or retrograde (n = 7) method. Control animals (n = 6) were not treated. Changes in regional preload recruitable stroke work were used to assess left ventricular performance before and after cardiopulmonary bypass. Two control animals could not be weaned from cardiopulmonary bypass. Left ventricular function was best preserved after treatment of induced coronary air embolism with retrograde cardioplegia (90% of baseline). Coronary air embolism treatment with antegrade cardioplegia resulted in diminished left ventricular performance (68% of baseline). In control animals left ventricular contractility was significantly impaired (39% of baseline). We conclude that administration of retrograde cardioplegic solution may be an effective method of treating coronary air embolism. The favorable outcome seen with cardioplegia may be in part because of its ability to protect the ischemic myocardium while the solution mechanically dislodges air from the vascular bed.

Asymptomatic microembolism in patients with long-term ventricular assist support

The incidence of clinically significant thromboembolic events is reported to be as high as 25% in patients with left ventricular assist devices (LVAD). Clinically detectable neurologic deficits resulting from thromboembolic events are reported to occur at a frequency of 0.0056% per patient-month with the Thermo Cardiosystems Heartmate 1000 (Woburn, MA) intraperitoneal LVAD (TCI). To date, the occurrence of asymptomatic cerebral microemboli in patients with this device has not been characterized. Transcranial doppler (TCD) monitorings were used for evaluation of the incidence of cerebral microembolism in 14 patients with the TCI LVAD. Studies were performed after LVAD support ranging from 7 to 305 days. Overall, 35 studies were obtained from the left middle cerebral artery for a duration of 30 minutes per study and the number of high intensity transient signals (HITS) were recorded. In one patient with a fatal stroke, an average of 0.86 HITS per study period (0.03/min) was observed. In 13 patients without any symptoms, an average of 0.46 HITS per study (0.016/min) was observed. Overall, no HITS were determined in 74% of the studies. Although the clinical significance or the nature of these microemboli is unknown, the data support that microembolism with the TCI LVAD is a rare event despite absence of anticoagulation. Long-term detailed neurocognitive testing and hematologic assessment is needed to establish the clinical relevance of these microemboli in patients with detected signals.

Bridge experience with long-term implantable left ventricular assist devices. Are they an alternative to transplantation?

BACKGROUND

If long-term use of left ventricular assist devices (LVADs) as bridges to transplantation is successful, the issue of permanent device implantation in lieu of transplantation could be addressed through the creation of appropriately designed trials. Our medium-term experience with both pneumatically and electrically powered ThermoCardiosystems LVADs is presented to outline the benefits and limitations of device support in lieu of transplantation.

METHODS AND RESULTS

Detailed records were kept prospectively for all patients undergoing LVAD insertion. Fifty-eight LVADs were inserted over 5 years, with a survival rate of 74%. Mean patient age was 50 years, and duration of support averaged 98 days. Although common, both preexisting infection and infection during LVAD support were not associated with increased mortality or decreased rate of successful transplantation. Thromboembolic complications were rare, occurring in only three patients (5%) despite the absence of anticoagulation. Ventricular arrhythmias were well tolerated in all patients except in cases of early perioperative right ventricular failure, with no deaths. Right ventricular failure occurred in one third of patients and was managed in a small percentage by right ventricular assist device (RVAD) support and/or inhaled nitric oxide therapy. There were no serious device malfunctions, but five graft-related hemorrhages resulted in two deaths. Finally, a variety of noncardiac surgical procedures were performed in LVAD recipients, with no major morbidity and mortality.

CONCLUSIONS

Over all, our medium-term experience with implantable LVAD support is encouraging. Although additional areas of investigation exist, improvements in patients selection and management together with device alterations that have reduced the thromboembolic incidence and facilitated patient rehabilitation lead us to believe that a prospective, randomized trial is indicated to study the role that LVADs may have as an alternative to medical management.

The continuing evolution of mechanical ventricular assistance

A great number of patients suffer and die of the sequelae of acute and chronic heart failure each year. Although advances in medical and surgical therapy have benefited many of these patients, most have disease that is refractory to any definitive therapy. For these patients cardiac transplantation is the only remaining hope. Unfortunately, because of the increasing demand for donor organs in the face of a fixed and limited supply, this option is available to only a small percentage of these patients. Even in patients accepted for transplantation, a significant waiting list mortality has been observed. A variety of VADs have been developed since the first successful case of mechanical cardiac assistance more than 30 years ago. These devices differ in basic mechanical function, method of insertion, and degree of implantability and thus have different indications and potential applications. Whereas the intraaortic balloon pump and centrifugal pumps are effective short-term support modalities, extracorporeal and implantable pulsatile devices have been used successfully for long-term support of patients with reversible and nonreversible cardiac failure. Although these pumps have most commonly been used as bridges to transplantation, increasing clinical experience has supported the notion of long-term mechanical assistance as a definitive therapy for patients with end-stage heart disease. Although complications, particularly infection and thromboembolism, pose significant challenges and long-term device reliability remains to be fully determined, available implantable devices appear to be capable of providing effective long-term support. As data are obtained from currently ongoing trials comparing VAD support with medical therapy for end-stage heart failure, ethical and economic issues will assume increasing importance.

Self-hypnosis reduces anxiety following coronary artery bypass surgery. A prospective, randomized trial

OBJECTIVE

The role of complementary medicine techniques has generated increasing interest in today's society. The purpose of our study was to evaluate the effects of one technique, self-hypnosis, and its role in coronary artery bypass surgery. We hypotesize that self-hypnosis relaxation techniques will have a positive effect on the patient's mental and physical condition following coronary artery bypass surgery.

EXPERIMENTAL DESIGN

A prospective, randomized trial was conducted. Patients were followed beginning one day prior to surgery until the time of discharge from the hospital.

SETTING

The study was conducted at Columbia Presbyterian Medical Center, a large tertiary care teaching institution.

PATIENTS

All patients undergoing first-time elective coronary artery bypass surgery were eligible. A total of 32 patients were randomized into two groups.

INTERVENTIONS

The study group was taught self-hypnosis relaxation techniques preoperatively, with no therapy in the control group.

MEASURES

Outcome variables studied included anesthetic requirements, operative parameters, postoperative pain medication requirements, quality of life, hospital stay, major morbidity and mortality.

RESULTS

Patients who were taught self-hypnosis relaxation techniques were significantly more relaxed postoperatively compared to the control group (p=0.032). Pain medication requirements were also significantly less in patients practising the self-hypnosis relaxation techniques that those who were noncompliant (p=0.046). No differences were noted in intraoperative parameters, morbidity or mortality.

CONCLUSION

This study demonstrates the beneficial effects self-hypnosis relaxation techniques on patients undergoing coronary artery bypass surgery. It also provides a framework to study complementary techniques and the limitations encountered.

Extended indications for lung volume reduction surgery in advanced emphysema

BACKGROUND

Lung volume reduction surgery has shown early promise as a palliative therapy in severe emphysema. Selection of potential candidates has been based on certain functional and anatomic criteria, and a variety of operative contraindications have been proposed.

METHODS

Over 15 months, we performed lung volume reduction surgery in 85 patients selected on the basis of severe hyperinflation with air trapping, diaphragmatic dysfunction, and disease heterogeneity. Patients were not excluded on the basis of severe hypercapnia, steroid dependence, profound pulmonary dysfunction, or inability to complete preoperative rehabilitation.

RESULTS

We observed significant improvements in pulmonary function, exercise capacity, and dyspnea, with an acceptable 30-day perioperative mortality of 7% and actuarial survival of 90% and 83% at 6 and 12 months, respectively. In each "high-risk" group, perioperative mortality, actuarial survival to 1 year, and functional results were equivalent, and in some cases superior, to those in the corresponding "low-risk" patients.

CONCLUSIONS

Severe hypercapnia, steroid dependence, profound pulmonary dysfunction, and inability to complete preoperative rehabilitation do not preclude successful lung volume reduction surgery and should not be regarded as absolute exclusionary criteria.

Immunologic assessment of patients treated with bovine fibrin as a hemostatic agent

Twenty-one cardiothoracic surgical patients have been treated with fibrin as a topical hemostatic/sealing agent, prepared from bovine fibrinogen clotted with bovine thrombin. Serum samples have been collected before treatment with fibrin and postoperatively between 1 and 9 days, 3 and 12 weeks, and 6 and 8 months. The titers of anti-bovine fibrinogen antibodies, measured by ELISA specific for immunoglobulins IgG or IgM, increased to maximal values after about 8 or 6 weeks, respectively. After 8 months, IgG titers were on average 20-fold lower than the mean maximal value, while IgM titers returned to the normal range. IgG was the predominant anti-bovine fibrinogen immunoglobulin as documented by ELISA, affinity chromatography and electrophoresis. Anti-bovine fibrinogen antibodies present in patients reacted readily with bovine fibrinogen, but did not cross-react with human fibrinogen as measured by ELISA or by immunoelectrophoresis. A significant amount of antibodies against bovine thrombin and factor V has been found, many cross-reacting with the human counterparts. No hemorrhagic or thrombotic complications, or clinically significant allergic reactions, occurred in any patient, in spite of antibody presence against some bovine and human coagulation factors. The treatment of patients with bovine fibrin, without induction of immunologic response against human fibrinogen, appeared to be an effective topical hemostatic/sealing measure.

Low thromboembolic risk without anticoagulation using advanced-design left ventricular assist devices

BACKGROUND

A major limitation of cardiac assist devices has been the high incidence of thromboembolic events and their requirement for systemic anticoagulation. The Thermo Cardiosystems HeartMate 1000 IP left ventricular assist device (LVAD) employs a design that may reduce thromboembolic risk and obviate the need for systemic anticoagulation.

METHODS

Two hundred twenty-three patients with nonreversible heart failure were supported with the HeartMate LVAD as a bridge to heart transplantation. All patients were monitored prospectively for thromboembolic events. Anticoagulation regimens and occurrence of subclinical thromboembolic events, including those seen by transcranial Doppler examinations in selected patients, were also recorded.

RESULTS

Total time of LVAD support use was 531.2 patient-months. Twenty-three patients (10%) received warfarin postoperatively for 42.4 patient-months (8.2% of total support time). Six patients (2.7%) had thromboembolic events, representing 0.011 events per patient-month of device use.

CONCLUSIONS

The thromboembolic complication rate associated with this LVAD is acceptably low despite the minimal anticoagulation employed in this series, allowing consideration of long-term device use for the treatment of heart failure.

Duration of left ventricular assist device support affects transplant survival

BACKGROUND

Left ventricular assist devices have become an important tool in the successful treatment of heart failure as bridges to transplantation. The optimal duration of device support before heart transplantation is debated. We report the effect of left ventricular device support duration on survival after heart transplantation.

METHODS

All patients bridged to heart transplantation with the ThermoCardiosystems Heartmate 1,000 IP left ventricular assist device between January 1, 1986, and October 15, 1994, were included in our study. Parameters studied included duration of support, measures of end-organ function, and complications while supported with the device. Patients supported < 30 days were compared with patients supported > 30 days before undergoing transplantation.

RESULTS

Patients supported for < 30 days had a threefold increased perioperative mortality compared with patients supported > 30 days (p = 0.031). Laboratory values of end-organ function were similar before left ventricular device insertion in both groups, although at the time of transplantation patients supported < 30 days had a significantly elevated bilirubin level compared with patients supported > 30 days (p < 0.001). Patients supported > 30 days had significantly more infections than the < 30 days group (p = 0.0345).

CONCLUSIONS

Patients supported for > 30 days with left ventricular assist devices have improved post-transplant perioperative survival because of normalization of end-organ function and improved physiologic status secondary to aggressive physical rehabilitation. Patients should be supported for > 30 days in combination with physical rehabilitation, to improve early survival after heart transplantation.

The influence of concordant xenografts on the humoral and cell-mediated immune responses to subsequent allografts in primates

The humoral and cell-mediated immune responses to subsequent allografts were determined in primate recipients after concordant xenotransplantation as a bridge to allotransplantation. Heterotopic heart transplants (n = 4) were performed from cynomolgus monkeys into ABH type-matched olive baboons followed 2 weeks later by allotransplantation from ABH type-matched baboon donors. Allografts were explanted at 8 weeks. All recipients underwent splenectomy at the time of xenotransplantation and received immunosuppression with cyclosporine, azathioprine, and methylprednisolone. Concordant xenotransplantation in these primates did not induce humoral or cell-mediated immune responses that jeopardized subsequent allografts. The degree of xenospecific immune reactivity, as determined by specific cytotoxicity of recipient T-cell lines derived from the xenograft and extent of histologic xenograft rejection, did not predict the severity of subsequent allograft rejection. In two of the four recipients, xenotransplantation induced an alloreactive humoral response against antigens expressed by the B cells of more than 50% of members from a panel of 12 unrelated baboons. In all recipients, priming with xenogeneic splenocytes in vitro induced an accelerated proliferative T-cell response to allogeneic lymphocytes from 16% of this panel. This study affirms the role of concordant xenografts as appropriate biologic bridges to human allotransplantation. However, our results suggest that xenoreactive baboon memory CD4 T cells may recognize major histocompatibility complex class II--like structures shared between the xenogeneic and allogeneic targets. The potential allorecognition induced by a xenograft may affect the process of subsequent allograft donor selection.

Indirect recognition of donor HLA-DR peptides in organ allograft rejection

To determine whether indirect allorecognition is involved in heart allograft rejection T cells obtained from peripheral blood and graft biopsy tissues were expanded in the presence of IL-2 and tested in limiting dilution analysis (LDA) for reactivity to synthetic peptides corresponding to the hypervariable regions of the mismatched HLA-DR antigen(s) of the donor. Serial studies of 32 patients showed that T cell reactivity to donor allopeptides was strongly associated with episodes of acute rejection. The frequency of allopeptide reactive T cells was 10-50-fold higher in the graft than in the periphery indicating that T cells activated via the indirect allorecognition pathway participate actively in acute allograft rejection. In recipients carrying a graft differing by two HLA-DR alleles the response appeared to target only one of the mismatched antigens of the donor. Indirect allorecognition was restricted by a single HLA-DR antigen of the host and directed against one immunodominant peptide of donor HLA-DR protein. However, intermolecular spreading was demonstrated in patients with multiple rejection episodes by showing that they develop allopeptide reactivity against the second HLA-DR antigen. These data imply that early treatment to suppress T cell responses through the indirect pathway of allorecognition, such as tolerance induction to the dominant donor determinant, may be required to prevent amplification and perpetuation of the rejection process.

Outpatient left ventricular assist device support: a destination rather than a bridge

BACKGROUND

To evaluate the feasibility and efficacy of outpatient left ventricular assist devices as a bridge to transplantation, we reviewed the initial clinical experience with this modality at our institution.

METHODS

During January 1993 to November 1995, 12 male and 2 female patients with an average age of 47 +/- 17 years were supported for an average of 117 +/- 24 days with the Thermo Cardiosystems VE wearable left ventricular assist device. Seven patients were discharged home an average of 35 +/- 4 days after implantation.

RESULTS

No device failures occurred, although 29 controller malfunctions were identified during 1,640 total support days. All patients were able to safely maintain their devices. Outflow graft bleeding and driveline infection were responsible for two readmissions. No long-term anticoagulation treatment was used; one small thromboembolic episode occurred, but without significant long-term sequelae.

CONCLUSIONS

None of the 7 patients released from the hospital died, and all were able to successfully maintain their devices at home. Hospital discharge of patients supported with left ventricular assist devices has allowed long-term evaluation of this technology, and the findings should prompt study of their use as a long-term alternative treatment to medical management for congestive heart failure.

Transluminal aortic valve placement. A feasibility study with a newly designed collapsible aortic valve

Percutaneous stents are used in vascular applications in conjunction with angioplasty and in combination with graft material for repair of abdominal aneurysms. The authors have designed a collapsible bioprosthetic aortic valve for placement by a transluminal catheter technique. This trileaflet stent valve is composed of stainless steel and bovine pericardium. Stent valves, 23 and 29 mm, were tested in a pulse duplicator system with rigid rings from 21 to 31 mm in 2 mm increments. At a mean flow of 3.1 L/min (+/-0.7), normal systemic aortic pressure was generated with a transvalvular gradient of 14.9 +/- 7 mmHg (mean +/- SD). Regurgitation fraction ranged from 10 to 18% (mean 13.8 +/- 3%) in the best ring size. Valves with the best hemodynamic profile were used for implantation in three 70 kg pigs in an open chest model. The valve was collapsed in a 24 Fr catheter designed to allow slow, controlled release. After resection of the native leaflets, the new valve was placed in the subcoronary position. No additional sutures were used for securing the valve. Two animals were successfully weaned from cardiopulmonary bypass and maintained systemic pressures of 100/45 (+/-10) and 116/70 (+/-15) mmHg, respectively. Intraoperative color echocardiography revealed minimal regurgitation, central flow, full apposition of all leaflets, and no interference with coronary blood flow. Both animals were sacrificed after being off bypass for 2 hr. Postmortem examination revealed the valves to be securely anchored. The third animal was weaned from cardiopulmonary bypass but developed refractory ventricular fibrillation because of valve dislodgment due to structural failure. Although long term survival data are needed, development of a hemodynamically acceptable prosthetic aortic valve for transluminal placement is feasible.

Transient normalization of systolic and diastolic function after support with a left ventricular assist device in a patient with dilated cardiomyopathy

A 19-year-old man who had fulminant heart failure caused by an idiopathic dilated cardiomyopathy was supported with a left ventricular assist device for 183 days as a bridge to heart transplantation. At the time of intended transplantation it was noted that the patient's heart had returned to normal size, had a normal ejection fraction, and was able to maintain normal pressures and flows. In view of the apparent recovery of cardiac properties, the left ventricular assist device was explanted and the transplantation was not performed. However, the heart dilated, ejection fraction worsened, and the patient died of heart failure exacerbated acutely by a systemic viral illness. Although such recovery of systolic function is uncommon, as use of the left ventricular assist devices becomes more widespread other physicians might encounter similar findings and, in this regard, they might find our experience useful as they contemplate their treatment options.

Jugular venous bulb oxyhemoglobin saturation during cardiac surgery: accuracy and reliability using a continuous monitor

Previous studies have demonstrated the feasibility of continuously monitoring jugular venous oxygen saturation (SjO2) with a fiberoptic catheter during hypothermic cardiopulmonary bypass (CPB). In the present study, with patients maintained at either moderate (28 degrees C) or mild (32-34 degrees C) hypothermia during CPB, SjO2 values obtained from a fiberoptic catheter were compared to intermittent samples analyzed by a co-oximeter. Twenty patients scheduled for elective coronary artery or valvular surgery had a 5.5 Fr Opticath catheter inserted into the left internal jugular bulb after induction of general anesthesia. The catheter was calibrated in vitro and in vivo according to the manufacturer's specifications. Catheter and co-oximetry SjO2 values obtained at four time points--1) pre-CPB, 2) target CPB temperature, 3) mid-rewarming, and 4) post-CPB--were compared using linear regression, Bland-Altman analysis, and Shrout-Fleiss interclass correlation coefficient analysis. These statistical methods revealed poor correlation between the catheter and co-oximetry SjO2 values: r = 0.44 by linear regression and 0.32 by interclass correlation coefficient analysis, and was unacceptably discrepant by Bland-Altman analysis. Oxyhemoglobin saturation values obtained continuously from a jugular venous bulb fiberoptic catheter during CPB may not accurately reflect true oxyhemoglobin saturation, and caution is warranted when interpreting SjO2 values obtained from a fiberoptic catheter during CPB.

Gastrointestinal consequences of left ventricular assist device placement

Left ventricular assist devices effectively improve hemodynamic function and reverse renal and hepatic dysfunction; however, their effects upon the gastrointestinal (Gl) system have not been addressed. We evaluated Gl function in 27 left ventricular assist device recipients using interviews, Gl contrast studies, endoscopy, and 99mTc sulfur colloid studies of esophageal transit and gastric emptying. While on left ventricular assist device support (mean duration of 84 days), 19 patients reported early satiety and/or nausea, and 1 was unable to tolerate oral intake. Esophageal transit time (normal, < 10 sec) was borderline slow at 14 +/- 4 (mean +/- standard error of the mean) and gastric emptying (normal < 90 min) was prolonged (range of 106-506 min, mean = 283 +/- 69 min). In a 1-38 month follow-up, gastric function subjectively improved in all. Six patients had intraperitoneal device placement. One died of aspiration pneumonia secondary to small bowel obstruction, and one had prolonged inability to tolerate oral intake, which required feeding jejunostomy tube placement. The 21 patients with pre peritoneal placement of the device did not require Gl operative interventions and had no catastrophic Gl events; they had mild to no Gl complaints. Pre peritoneal placement may mitigate early satiety and obviate serious Gl complications.

Right ventricular obstruction in aortic dissection: a mechanism of hemodynamic collapse

The main and right pulmonary arteries may be compressed by the false lumen of a type I aortic dissection. We report a 73-year-old women with a dissection of the aorta in whom echocardiographic examination revealed acute pulmonary arterial compression causing right ventricular failure and hemodynamic collapse.