Jiro Kurita

Enhanced Vascularization by Controlled Release of Platelet-Rich Plasma Impregnated in Biodegradable Gelatin Hydrogel

BACKGROUND Platelet-rich plasma (PRP) contains numerous growth factors that have angiogenic activities. However, the PRP-induced angiogenesis is limited by the short half-life period of growth factors. A new drug delivery system of biodegradable gelatin hydrogel was designed to achieve the controlled release of growth factors in PRP. The purpose of this study is to demonstrate the therapeutic efficacy of slow-release of PRP in the inducing of angiogenesis for critical ischemia. METHODS The PRP was prepared from the whole blood of inbred rats. Thirty-two rats underwent excision of the left femoral artery and its branches to create critical limb ischemia. The rats were randomized into four groups (n=8 each): no treatment (control), intramuscular injection of platelet-poor plasma (PPP), PRP only, or a combination of PRP and gelatin hydrogel (PRP+Gel). Four weeks after the treatment, angiogenesis was evaluated by laser doppler, microangiogram, and immunohistology. RESULTS The resultant number of platelets for PRP was higher than that of PPP (p<0.01). The concentrations of vascular endothelial growth factor, transforming growth factor-β1, and platelet-derived growth factor-BB were significantly higher in PRP animals than in PPP (p<0.01). Although the PRP group improved tissue blood flow (82.7%±6.2%) compared with the control group or PPP group (69.6±12.2 or 72.2±11.8%, p<0.05), the improvement of blood flow in the PRP+Gel group was significantly better (95.1%±8.0%, p<0.05) than in the PRP group. Angiographic score in the PRP+Gel group was significantly higher than that in the control, PPP, and PRP groups (8.6±2.1 versus 3.8±0.8, 3.7±0.6, and 5.6±1.5, respectively; p<0.01). Capillary density also increased immunohistologically in the PRP+Gel group when compared with the control, PPP, and PRP groups (p<0.01). CONCLUSIONS A controlled release system of PRP was effective in inducing angiogenesis for critical ischemia. The biodegradable gelatin hydrogel incorporating PRP as applicable could possibly be used to treat for patients with ischemic cardiomyopathy.

Intraoperative verification of conduction block in atrial fibrillation surgery

BACKGROUND Atrial tachycardia is a troublesome and medically refractory complication after surgery for atrial fibrillation. Incomplete surgical ablation during atrial fibrillation surgery can result in residual conduction over the lesions and postoperative atrial tachycardia. Intraoperative verification of conduction block would detect incomplete ablation lesions and direct repeat ablations to prevent postoperative atrial tachycardia. METHODS The incidence of postoperative atrial tachycardia was examined in 218 patients who underwent atrial fibrillation surgery between November of 1994 and October of 2007. No conduction block across any ablation lesions was confirmed intraoperatively in the first 128 patients (group C). Isolation of each pulmonary vein was verified by intraoperative pulmonary vein pacing in the following 72 patients (group PV). In the recent 18 consecutive patients, conduction block in the coronary sinus, in addition to pulmonary vein isolation, was confirmed by intraoperative coronary sinus pacing (group PV/CS). Postoperative atrial tachycardia was characterized by electroanatomic mapping. RESULTS The incidence of postoperative atrial tachycardia in groups C and PV was 7% and 1%, respectively (P = .0985). No patients exhibited any postoperative atrial tachycardia in group PV/CS. The postoperative electroanatomic mapping revealed that the mechanisms of the atrial tachycardia were macro-reentry through incomplete coronary sinus and mitral valve ablation lesions (n = 9), and focal activation in the coronary sinus (n = 1). Intraoperative verification of conduction block directed the repeat ablation lesions to the pulmonary veins. CONCLUSION The majority of postoperative atrial tachycardia was associated with an incomplete coronary sinus ablation. Intraoperative verification of conduction block may be helpful to prevent the occurrence of postoperative atrial tachycardia.

Intraoperative Electroanatomic Mapping

PURPOSE An electroanatomic mapping system using an electromagnetic navigation technology constructs a 3-dimensional structure of the heart with high geometric accuracy of the data that provides a precise localization of the substrates of arrhythmias. The system was tested for the feasibility and efficacy in intraoperative mapping. DESCRIPTION The strength of the magnetic field is measured by a location sensor with three different frequencies generated by a location pad placed beneath the operating table, and the spatial location of the sensor is determined. By roving the catheter on the heart while the local electrogram is recorded simultaneously, the 3-dimensional figure of the heart is reconstructed and an activation or voltage map is generated. EVALUATION The system was used in 19 patients with ventricular tachycardia or other arrhythmias. The focus or reentrant circuit of the tachycardia was precisely located and a map-guided procedure was successfully performed in all patients. Cardiopulmonary bypass allowed for the tachycardias to be mapped without any hemodynamic compromise. CONCLUSIONS Intraoperative mapping using the electroanatomic mapping system enables a precise localization of the tachycardia substrate.