Biventricular assist device as a bridge to transplantation in a pediatric patient

Development and Initial in Vivo Testing of a New Hydraulic Drive System (Paedipump) for Circulatory Support in Infants

The main limitation in the use of circulatory support in children is the lack of an adequate system with regard to size and pumping capacity Recently, two pneumatically driven ventricular support systems with low volume chambers for use in a pediatric population became available. We have developed a hydraulic drive system with an advantageous exact control of the stroke volume. The system enables two different modes of operation: the full-empty and the filled-empty modes. In both cases the ventricle is empty at the end of systole.

This new system was tested in experimental animals (6 pigs, body weight 9.5–14.0 kg) with normal and reduced left ventricular function (MAP<45 mmHg). A 25 ml ventricle (HIA-Medos) was implanted. The full-empty and the filled-empty mode used led to a significant load reduction, both in animals with normal and impaired cardiac function. Plasma lactate levels, pH-values and total body 0 2 consumption were in the normal range during circulatory support indicating adequate organ perfusion.

Results showed that sufficient ventricular support was achieved during all pumping modes due to the possibility of controlling and modifying the stroke volume of the hydraulically driven support system employed according to necessity. This is a promising feature for its future application in infants with congenital or acquired heart diseases.

Right Ventricle to Pulmonary Artery Reconstruction Using a Valved Homograft

Although the valved homograft is widely used to establish a connection between the right ventricle (RV) and the pulmonary artery (PA), its durability remains controversial. In the present study, the data on 141 valved homograft implantations in 107 consecutive patients performed from January 1990 to June 2000 were analyzed. The mean follow-up period was 4.6 years (range, 0.2-9.4 years). The clinical data, including clinic records, operative notes, follow-up visits, and letters from referring physicians, were analyzed with particular reference to variables associated with early and late mortality, deterioration of the homograft, and risk factors for patient survival and homograft failure. Early death occurred in 7.5% (n=8) of the cases, and each of these patients died without leaving the hospital. Late death occurred in 2 patients, for whom the cause of death was suggested to be related to arrhythmia. Thirteen patients underwent catheter intervention (ie, balloon dilatation and/or stenting) and 8 of these did not require homograft replacement following catheterization. The overall survival rate at both 3 years and 5 years was 88.9+/-3.4%. Cumulative freedom from total homograft failure was 82.5+/-3.6% at 1 year; 61.6+/-5.0% at 3 years; and 42.4+/-6.2% at 5 years. In comparison with 2 criteria of homograft failure (ie, total homograft failure and homograft failure including catheter intervention), the incidence of freedom from homograft failure including catheter intervention was lower than that of total homograft failure, although the difference was not statistically significant. In the multivariate analysis, significant risk factors with respect to patient survival were homograft replacement and the use of expanded polytetrafluoroethylene (ePTFE); those judged to be significant with respect to homograft failure were total repair with first homograft implantation and diagnosis of truncus arteriosus. The valved homograft was thus considered an appropriate choice of conduit between the RV and the PA, and it provided excellent patient survival. However, this type of homograft did not provide a completely permanent solution for the repair of complex cardiac anomalies. Therefore, the use of ePTFE for homograft extensions should be avoided. Finally, the results suggest that catheter intervention plays an important role in the longevity of the implanted homograft.

Use of assist devices and ECMO to bridge pediatric patients with cardiomyopathy to transplantation

BACKGROUND

Pulsatile ventricular assist devices (VADs) are used to bridge adults with end-stage heart disease to transplantation. A combination of external implantable pulsatile and continuous-flow external mechanical support now can be used to bridge pediatric patients with end-stage cardiomyopathy to orthotopic heart transplantation (OHT).

METHODS

We reviewed consecutive pediatric patients with cardiomyopathy (n = 28) who required mechanical cardiac support from July 1995 to February 2001. All were OHT candidates with severe hemodynamic compromise despite maximal medical support. We excluded from this series patients who had undergone cardiotomy.

RESULTS

Nineteen patients received support from external continuous-flow devices, either with extracorporeal membrane oxygenation or with centrifugal VADs, and 9 patients received pulsatile support. Nineteen of 28 (68%) patients were successfully bridged to transplant (17) or weaned (2) from their devices after recovery. Of the patients successfully bridged to transplant or recovery, 89% are alive to date. Univariate analysis revealed that a lower bilirubin concentration after 2 days of support was associated with a favorable outcome (p = 0.006). As expected, the patients with pulsatile VADs had significantly higher rates of extubation and oral feeding.

CONCLUSION

Pulsatile and continuous-flow devices can complement each other to significantly extend the lives of a wide range of pediatric patients with severe cardiomyopathies.

Intra-aortic balloon pumping in children with dilated cardiomyopathy as a bridge to transplantation

Children with dilated cardiomyopathy awaiting transplantation who fail maximal pharmacologic therapy may benefit from intra-aortic balloon pumping. Between July 1993 and August 1999, a total of 4 children with dilated cardiomyopathy underwent pre-transplant balloon pumping for 6.0 +/- 5.8 (1 to 12) days. One child (pumped for 12 days) died awaiting transplant, and the remaining 3 were successfully transplanted. Intra-aortic balloon pumping timed precisely with M-mode echocardiographic markers offers a relatively simple and safe intermediate level of mechanical support for children with dilated cardiomyopathy who fail pharmacologic support.

[Clinical guidelines of the Spanish Society of Cardiology for the most frequent congenital cardiopathies]

The use of diagnostic and therapeutic techniques is very important to ensure optimum, effective treatment in patients with heart disease to thereby obtain an adequate cost-benefit relationship. The aim of establishing guidelines for the evaluation and management is to achieve this relationship, but these guidelines are difficult to establish in pediatric cardiology despite 50 years of experience in this field. At present a large group of patients may benefit from these guidelines due to the improvement in the diagnostic techniques and better treatment results in congenital heart disease in the newborn. Protocols have been established in some groups and in others in which this is not possible, descriptive analysis and therapeutic schedules have been determined.

Minimally invasive mechanical cardiac support without extracorporeal membrane oxygenation in children awaiting heart transplantation

BACKGROUND

Mechanical cardiac assist for small children (< 30 kg) requiring bridge strategy to orthotopic heart transplantation often requires sternotomy for cannulation access to ensure perfusion to the aortic arch. Extracorporeal membrane oxygenation (ECMO) through neck cannulation is an option in very small (< 10 kg) patients, but the risk of stroke is increased in larger children. Another disadvantage is poor decompression of the left atrium, which can cause persistent pulmonary edema.

METHODS

Two cases are used to illustrate two methods of avoiding sternotomy during mechanical assist in children with dilated cardiomyopathy. One of these approaches avoids the need for extracorporeal oxygenation.

RESULTS

Decompression of the left-sided chambers with a left atrial cannula decreased pulmonary edema and improved pulmonary function.

CONCLUSIONS

Pediatric patients with dilated cardiomyopathy may benefit from a left ventricular assist technique using a centrifugal pump, which avoids the neck vessels and sternotomy, as well as ECMO.

Pulsatile pediatric ventricular assist devices: Current results for bridge to transplantation

While pulsatile ventricular assist devices have gained widespread use in adult patients awaiting heart transplantation, only very limited experience with these devices exists in the pediatric population. In the past mostly non-pulsatile systems such as ECMO have been used to support pediatric patients with heart failure for very limited periods of time. Only recently have miniaturized pulsatile devices became available. This article describes the technical characteristics of these devices which have been implanted at the Deutsches Herzzentrum Berlin since 1992. The Berlin Heart assist device has since been used in 34 children between the ages of 6 days and 16 years. We report our strategy in patient selection, perioperative care and subsequent heart transplantation. The current literature on mechanical circulatory support in children is reviewed. Copyright 1999 by W.B. Saunders Company

Alternative technique of right-sided outflow cannula insertion for right ventricular support

Right ventricular assist devices are an important part of the armamentarium of cardiac surgeons for the treatment of right-sided circulatory failure after cardiac transplantation or insertion of a left ventricular assist device. However, right ventricular assist device insertion can be technically challenging in the setting of pulmonary hypertension because of a number of concomitant anatomic and physiologic phenomena. We present a technique for the insertion of the right ventricular assist device outflow cannula that is easier and faster to insert, and safer to explant, especially if cardiopulmonary bypass is to be avoided.

Pediatric solid organ transplantation

Solid organ transplantation offers hope for long-term survival and more normal lifestyles for children. Many of the procedures used are scaled-down versions of those used in adults and are associated with distinct challenges in children. Recent studies have provided insights into how transplantation can best serve these patients.