Right ventricular outflow tract reconstruction with decellularized porcine xenografts in patients with congenital heart disease.

BACKGROUND AND AIM OF THE STUDY: Decellularized xenogeneic pulmonary valves have been introduced for right ventricular outflow tract (RVOT) reconstruction in congenital heart disease. In the present study, the intermediate-term results from three institutions were analyzed. METHODS: Between January 2006 and September 2008, a total of 61 patients (median age 7 years; range: 9 days to 50 years; median body weight 21 kg; range: 1.9-140 kg) underwent RVOT reconstruction with either the Matrix P (n = 9) or Matrix P Plus (n = 52) tissue-engineered conduit. Eighteen patients underwent surgery in infancy, and 31 patients had previously undergone one or more RVOT interventions or operations. RESULTS: The valve sizes ranged from 11 to 27mm. Five patients died during the hospital stay or within three months, from non-valve-related causes; hence, the early mortality was 8.2%. No deaths occurred during the follow up period. Reoperation due to valve failure became necessary in four patients; three patients underwent RVOT interventions due to distal anastomotic stenosis, and six reinterventions were performed distal to the valve due to hypoplastic branch pulmonary arteries. Patients with valve implantation during infancy showed a composite freedom from valve-related reoperation, catheter intervention or valve dysfunction (defined as dP(max) > 40 mmHg) of 87% at one and three years postoperatively. Both, computed tomography and magnetic resonance imaging studies demonstrated normal structural features, with no evidence of calcification. CONCLUSION: The Matrix P/Matrix Plus conduit represents a viable alternative for RVOT reconstruction in patients with congenital heart disease. The intermediate-term performance of the conduits was favorable compared to that of other currently available implants.

ICD therapy in children and young adults: low incidence of inappropriate shock delivery.

INTRODUCTION: Implantable cardioverter defibrillator (ICD) therapy of life-threatening arrhythmias in pediatric patients is feasible; however, recent studies report a high incidence of inappropriate shock deliveries. METHODS: The data of all recipients of an ICD at the Charité, Department of Pediatric Cardiology, between January 2001 and November 2007 were retrospectively analyzed regarding underlying cardiac disorders, arrhythmias, medication, ablation procedures, leads and devices, programming, and ICD therapies. RESULTS: A total of 33 patients underwent ICD implantation, with a median age of 16.5 years (range 8-36 years) and a mean weight of 61 +/- 20.9 kg. Underlying cardiac disorders were electrical heart disease (27%), cardiomyopathy (30%), congenital heart disease (33%), and others (9%). Eighty-five percent received antiarrhythmic drugs, and 12 ablation procedures were performed in nine patients (27%). The devices were programmed individually according to the underlying diseases and arrhythmias. During follow-up, a total of 63 shock therapies were delivered in 11 patients, while a majority of 34 shocks occurred in one patient (no therapies in 22 of 33 patients). Only two such therapies were inappropriate, both delivered for atrial flutter. CONCLUSIONS: In children and young adults receiving ICD therapy, the combination of strategies to prevent ventricular arrhythmias using specific drug therapy, ablation procedures, and individual programming with improved devices and leads causes a low incidence of inappropriate shock delivery.

A new biological matrix for septal occlusion.

The ideal septal occluder scaffold should promote the healthiest and most complete healing response possible while eventually facilitating the full resorption of the material, leaving "native" tissue behind. An excellent biocompatibility of the scaffold tissue is a prerequisite for quick, complete, and firm ingrowth of the device, optimizing outcomes and minimizing the potential for complications. Intestinal collagen layer (ICL) is a highly purified (acellular) bioengineered type-1 collagen derived from porcine submucosa. It is gradually resorbed by the host organism and subsequently replaced by the host tissue. CardioSEAL occluders were modified by substituting the conventional polyester fabric for an intestinal collagen layer (ICL). Percutaneous transcatheter closure of interventionally created atrial septal defects was performed in lambs using these modified occluders. A complete pathomorphological investigation including histology was carried out after 2, 4, and 12 weeks follow-up. Standard CardioSEAL implants served as a control group. After 2 weeks in vivo the devices were already covered completely by neo-endothelium. Compared with the conventional synthetic scaffold, ICL devices showed a quicker endothelialization, decreased thrombogenicity, and superior biocompatibility with no significant cellular infiltration observed in the histology of explants with ICL fabrics. After 3 months in vivo the collagen layer remained mechanically intact, but began to show the first histological signs of mild disintegration, gradual resorption, and remodeling. In conclusion, short-term results from preliminary in vivo experiments using a bioengineered collagen matrix as the occluder tissue scaffold showed excellent biocompatibility. This resulted in superior overall results: quicker endothelialization, a decreased thrombogenicity, and decreased immunological host response.

Origin of electrical activation within the right atrial and left ventricular walls: differentiation by electrogram characteristics using the noncontact mapping system.

Clinical data using the noncontact mapping system (Ensite 3000) suggest that characteristics of the reconstructed unipolar electrograms may predict the origin of electrical activation within the atrial and ventricular walls (endocardial vs myocardial vs epicardial origin). Experimental data are lacking. In ten open-chest pigs (mean body weight 62 kg) cardiac pacing was performed at a cycle length of 600 ms with a pulse width of 2 ms and twice diastolic threshold from the endo-, the myo-, and the epicardium, respectively. Pacing was undertaken at three right atrial and three left ventricular sites, and cardiac activation was recorded with the Ensite system. Reconstructed unipolar electrograms at the location of earliest endocardial activation assessed by color coded isopotential maps were analyzed systematically for differences in morphology. The positive predictive value of atrial electrograms exhibiting an initial R wave during pacing for a subendocardial origin (i.e., myocardial or epicardial) was 0.96. The negative predictive value was 0.48. Electrograms generated during myocardial pacing exhibited increased maximal negative voltage and maximal dV/dt (-3 +/- 1.8 mV, -798 +/- 860 mV/ms, respectively) than the electrograms obtained during endocardial (-2 +/- 1 mV, -377 +/- 251 mV/ms, respectively) and epicardial pacing (-2.1 +/- 0.7 mV, -440 +/- 401 mV/ms, respectively, P<0.01 for both parameters). During pacing at the left ventricular wall, occurrence of an initial R wave did not differ significantly between electrograms reconstructed during endocardial and subendocardial pacing. All other characteristics of the unipolar ventricular electrograms analyzed, except latency, did not differ significantly when compared to stimulation depth. Morphological characteristics of unipolar electrograms generated by the noncontact mapping system during pacing of the atrium allowed for discrimination of an endocardial versus a subendocardial origin of activation. At the ventricular level, characteristics of unipolar electrograms did not predict the origin of cardiac activation in this experimental setting.