Cath: Melody Valve in Contegra Graft - Animal Study

Circulation. 2010;122:A19333

Abstract 19333: Transcatheter Delivery of Melody Valves (MelV) Larger Than Contegra Conduit (CC)

Core 3. Genetics, Genomics and Congenital CV Disorders Session Title: Cardiac Catheterization and Electrophysiology in the Young

Prakul Chanthong; Luis Quinonez; Patty Boylen; Jon Timinsky; James Y Coe

UNIVERSITY ALBERTA HOSPITAL, Edmonton, Canada; Medtronic Canada, Missisauga, Canada; UNIVERSITY ALBERTA HOSPITAL, Edmonton, Canada

Transcatheter replacement of pulmonary valves is used in failed right ventricular to pulmonary artery (RV-PA) homografts (H) or prosthetic valves (PV). The former calcify and the latter have metal rings ± struts, both providing secure landing spots for MelV. The MelV expansion is limited by the H or PV size, and H may rupture if expanded beyond its original diameter. CCs often do not calcify, yet may become aneurysmal with increased intraluminal pressure. We tested the hypothesis that transcatheter MelV replacement is possible in a hypertensive, supported CC. Under general anesthesia, supported 18 mm CCs were placed as descending aortic jump grafts via a left thoracotomy in sheep (n=6). After a recovery period, 22 mm MelVs (n=4) were delivered via a carotid artery into the CCs. 56-82 (mean 72) days after aortic placement, the 18 mm CC dilated to 36-37 mm under systemic pressure, while the ring diameter remained at 18 mm. Deploying the MelV at 22 mm expanded the CC rings to 22 mm. without CC rupture. Transcatheter Melody valve replacement into the Contegra conduits is feasible. The Melody valve will expand the rings of the Contegra conduit to the largest valve diameter.

Author Disclosures: P. Chanthong, None; L. Quinonez, None; P. Boylen, Medtronic, Modest, Employment; J. Timinsky, None; J.Y. Coe, Medtronic, Modest, Consultant/Advisory Board; NuMed, Modest,Consultant/Advisory Board.

Remote Ischemic Preconditioning - Animal Study

Circulation. 2011;123:714-721
Full Text

Remote Ischemic Preconditioning Protects the Brain Against Injury After Hypothermic Circulatory Arrest

Hanna A. Jensen, MD, PhD*; et al.
Correspondence to Hanna Jensen, MD, Clinical Research Center, Oulu University Hospital, P.O. Box 5000, Oulu University 90014, Finland. E-mail hanna.alaoja.jensen@gmail.com

Background— Ischemic preconditioning (IPC) is a mechanism protecting tissues from injury during ischemia and reperfusion. Remote IPC (RIPC) can be elicited by applying brief periods of ischemia to tissues with ischemic tolerance, thus protecting vital organs more susceptible to ischemic damage. Using a porcine model, we determined whether RIPC of the limb is protective against brain injury caused by hypothermic circulatory arrest (HCA).

Methods and Results— Twelve piglets were randomized to control and RIPC groups. RIPC was induced in advance of cardiopulmonary bypass by 4 cycles of 5 minutes of ischemia of the hind limb. All animals underwent cardiopulmonary bypass followed by 60 minutes of HCA at 18°C. Brain metabolism and electroencephalographic activity were monitored for 8 hours after HCA. Assessment of neurological status was performed for a week postoperatively. Finally, brain tissue was harvested for histopathological analysis.

Study groups were balanced for baseline and intraoperative parameters. Brain lactate concentration was significantly lower (P<0.0001, ANOVA) and recovery of electroencephalographic activity faster (P<0.05, ANOVA) in the RIPC group. RIPC had a beneficial effect on neurological function during the 7-day follow-up (behavioral score; P<0.0001 versus control, ANOVA). Histopathological analysis demonstrated a significant reduction in cerebral injury in RIPC animals (injury score; mean [interquartile range]: control 5.8 [3.8 to 7.5] versus RIPC 1.5 [0.5 to 2.5], P<0.001, t test).

Conclusions— These data demonstrate that RIPC protects the brain against HCA-induced injury, resulting in accelerated recovery of neurological function. RIPC might be neuroprotective in patients undergoing surgery with HCA and improve long-term outcomes. Clinical trials to test this hypothesis are warranted.

EP: Do ablation lesions grow in size?

Circulation: Arrhythmia and Electrophysiology 2011

Enlargement of Catheter Ablation Lesions in Infant Hearts with Cryothermal Enlargement of Catheter Ablation Lesions in Infant Hearts with Cryothermal Versus Radiofrequency Energy: An Animal Study

1. Paul Khairy*,
2. Peter G. Guerra,
3. Lena Rivard,
4. Jean-François Tanguay,
5. Evelyn Landry,
6. Marie-Claude Guertin,
7. Laurent Macle,
8. Berndard Thibault,
9. Jean-Claude Tardif,
10. Mario Talajic,
11. Denis Roy and
12. Marc Dubuc

Abstract

Background—Radiofrequency catheter ablation in immature hearts has been associated with marked enlargement of lesions over time, with potential for related late adverse events. It remains unknown whether cryothermal ablation lesions display a similar pattern of growth.

Methods and Results—Ablation lesions (n=384) were performed in 32 infant miniature swine in right and left atria, ventricles, and atrioventricular (AV) grooves preselected by a randomized factorial design devised to compare radiofrequency and cryothermal lesions produced by 7-French 4 mm electrode-tip catheters. Animals were sacrificed acutely or at 1, 6, or 12 months according to the randomization scheme. The miniature swine weighed 8.8±1.2 kg and were 63±13 days of age at time of ablation. The minimum temperature during cryoablation was -79.8±3.4°C and the average temperature during radiofrequency ablation was 54.4±5.5°C. On morphometric analyses, no differences in the rate of growth of ablation lesions were noted between the two energy modalities in atria (P=0.44), ventricles (P=0.57), or AV grooves (P=0.69). Lesion volumes increased 3.3-fold in atria [95% confidence interval (CI) 2.3, 4.3, P=0.001] and 2.2-fold in ventricles [95% CI (1.4, 3.0), P<0.0001], p="0.22)." p="">

Conclusions—Ablation lesions produced by cryothermal energy in immature atrial and ventricular myocardium enlarge to a similar extent to radiofrequency ablation. In contrast, AV groove lesion volumes do not increase significantly with either energy modality.