Torsten Malm

Low-energy epicardial pacing in children: the benefit of autocapture

BACKGROUND Permanent cardiac pacing in children results commonly in augmented energy consumption because of the high pacing rates and the ample stimulation safety margin applied in children. Cardiovascular anatomy and limited venous access sometimes preclude the otherwise preferred endocardial approach. In this multicenter patient series, we studied the feasibility, safety, and energy saving obtained by a combination of steroid-eluting epicardial leads with autocapture devices capable of ongoing adjustment of the stimulation output to the prevailing threshold. METHODS Autocapture devices (Pacesetter Microny SR+/- and Regency SR+/-; Pacesetter, Solna, Sweden) and steroid-eluting epicardial pacing leads (Medtronic CapSure Epi 10366; Medtronic, Inc, Minneapolis, MN) were implanted in 14 children. Thresholds, telemetry data, evoked response, and polarization signals were obtained at discharge and follow-up, and battery service life was calculated. RESULTS During a median follow-up of 6.5 months, autocapture pacing was applied in 12 of 14 children. The automatically adjusted pulse amplitude of autocapture devices demonstrated low-energy pacing with no significant changes between discharge and 6 months follow-up (1.1 +/- 0.3 versus 0.9 +/- 0.3 V). Autocapture-programmed pacemakers had calculated life spans of 7.8 +/- 1.4 years (Microny) and 21.0 +/- 1.6 years (Regency). No adverse effects were noted. CONCLUSIONS Autocapture-controlled pacing with bipolar epicardial pacing leads is feasible and safe in children. Autocapture programming results in substantial energy savings and extends battery life markedly.

Heart transplantation across the antibodies against HLA and ABO.

We have intentionally performed heart transplantation in a 5‐year‐old child, despite the most unfavourable risk factors for patient survival; the presence of high level of antibodies against donors human leucocyte antigen (HLA) class I/II and blood group antigens. Pretransplant treatment by mycophenolate mofetil, prednisolone, tacrolimus, intravenous immunoglobulin, rituximab, protein‐A immunoadsorption (IA) and plasma exchange reduced antibody titres against the donors lymphocytes from 128 to 16 and against the donors blood group antigen from 256 to 0. The patient was urgently transplanted with a heart from an ABO incompatible donor (A1 to O). A standard triple‐drug immunosuppressive protocol was used. No hyperacute rejection was seen. Antibodies against the donors HLA antigens remained at a low level despite three acute rejections. Rising anti‐A1 blood group antibodies preceded the second rejection and were reduced by two blood group‐specific IAs and remained at a low level. The patient is doing well despite the persistence of donor‐reactive antibodies.

Successful Thrombolysis of an Occluded Modified Blalock Shunt Three Days After Operation

A 10-day-old boy with pulmonary atresia received a right-sided aortopulmonary polytetrafluoroethylene shunt. Three days after the operation he became cyanotic and was reintubated. Shunt occlusion was confirmed with angiography. Recombinant tissue plasminogen activator was given locally into the proximal end of the shunt. The thrombus was completely resolved after 2 days. When administration of recombinant tissue plasminogen activator was stopped, heparin infusion was started for 5 days. Shunt patency was demonstrated by angiography at 3 months postoperatively.

No evidence for mosaic pathogenic copy number variations in cardiac tissue from patients with congenital heart malformations.

The aim of this study was to investigate if pathogenic copy number variations (CNVs) are present in mosaic form in patients with congenital heart malformations. We have collected cardiac tissue and blood samples from 23 patients with congenital heart malformations that underwent cardiac surgery and screened for mosaic gene dose alterations restricted to cardiac tissue using array comparative genomic hybridization (array CGH). We did not find evidence of CNVs in mosaic form after array CGH analysis. Pathogenic CNVs that were present in both cardiac tissue and blood were detected in 2/23 patients (9%), and in addition we found several constitutional CNVs of unclear clinical significance. This is the first study investigating mosaicism for CNVs in heart tissue compared to peripheral blood and the results do not indicate that pathogenic mosaic copy number changes are common in patients with heart malformations. Importantly, in line with previous studies, our results show that constitutional pathogenic CNVs are important factors contributing to congenital heart malformations.

Long-Term Outcome of Homograft Implants Related to Donor and Tissue Characteristics

BACKGROUND Cardiovascular homografts are used for right ventricular outflow tract reconstruction. The procedure has excellent survival rates, but many homografts degenerate and require reintervention. Studies analyzing risk factors for reintervention most often focus on recipient and homograft characteristics, with identification of risk factors such as young recipient age and the use of aortic homografts. This study focuses on less known variables, including donor characteristics and homograft management and its effect on long-term outcome of homograft implantation. METHODS A retrospective study was conducted of 304 patients undergoing right ventricular outflow tract reconstruction at University Hospital Lund, Sweden, between 1995 and 2008. Follow-up was up to 22 years. Donor, homograft, and recipient characteristics were analyzed. Statistical analyses included the Kaplan-Meier method with log-rank test and Cox proportional hazard regression. RESULTS Follow-up was 98% complete. There were 12 deaths, and 115 reinterventions were required. Younger donor age was identified as a risk factor. Homografts from multiorgan donors with no ischemic time produced the longest homograft survival. In non-heart-beating donors, long-term results did not differ between 1 and 24 hours of ischemic time and more than 24 hours of ischemic time. Longer retrieval to cryopreservation times seemed to be better compared with shorter time intervals. Long-term outcome was superior in homografts from middle-aged donors. CONCLUSIONS The best long-term outcome was found when homografts were retrieved from organ donors and middle-aged donors. There is no harm extending the ischemic time in non-heart-beating donors to 48 hours to increase the number of possible donors.

Smart placement of a mediastinal drain in a neonate who requires a postoperative open sternum.

Crowding of the mediastinum after complex cardiac repair procedures in neonates and young children is a frequent problem. To create space, the sternal wound is kept open, commonly with a plastic stent, for later closure. Despite this maneuver, space is still an issue, and appropriate placement of the mediastinal drain can become a challenge. In this article we describe a simple and effective way to eliminate the problem. Holes are made in the sternal stent, and the drain is pulled through these holes. The drain is elevated away from the heart surface and does not contribute to the crowding.