Outcomes in cardiac surgery in 500 consecutive Jehovah's Witness patients: 21 year experience.

BACKGROUND: Refusal of heterogenic blood products can be for religious reasons as in Jehovah's Witnesses or otherwise or as requested by an increasing number of patients. Furthermore blood reserves are under continuous demand with increasing costs. Therefore, transfusion avoidance strategies are desirable. We describe a historic comparison and current results of blood saving protocols in Jehovah's Witnesses patients. METHODS: Data on 250 Jehovah's Witness patients operated upon between 1991 and 2003 (group A) were reviewed and compared with a second population of 250 patients treated from 2003 to 2012 (group B). RESULTS: In group A, mean age was 51 years of age compared to 68 years in group B. An iterative procedure was performed in 13% of patients in group B. Thirty days mortality was 3% in group A and 1% in group B despite greater operative risk factors, with more redo, and lower ejection fraction in group B. Several factors contributed to the low morbidity-mortality in group B, namely: preoperative erythropoietin to attain a minimal hemoglobin value of 14 g/dl, warm blood cardioplegia, the implementation of the Cornell University protocol and fast track extubation. CONCLUSIONS: Cardiac surgery without transfusion in high-risk patients such as Jehovah Witnesses can be carried out with results equivalent to those of low risk patients. Recent advances in surgical techniques and blood conservation protocols are main contributing factors.

In vivo quantitative mapping of myocardial stiffening and transmural anisotropy during the cardiac cycle.

Shear wave imaging was evaluated for the in vivo assessment of myocardial biomechanical properties on ten open chest sheep. The use of dedicated ultrasonic sequences implemented on a very high frame rate ultrasonic scanner ( > 5000 frames per second) enables the estimation of the quantitative shear modulus of myocardium several times during one cardiac cycle. A 128 element probe remotely generates a shear wave thanks to the radiation force induced by a focused ultrasonic burst. The resulting shear wave propagation is tracked using the same probe by cross-correlating successive ultrasonic images acquired at a very high frame rate. The shear wave speed estimated at each location in the ultrasonic image gives access to the local myocardial stiffness (shear modulus µ). The technique was found to be reproducible (standard deviation ) and able to estimate both systolic and diastolic stiffness on each sheep (respectively µ(dias) ≈ 2 kPa and µ(syst) ≈ 30 kPa). Moreover, the ability of the proposed method to polarize the shear wave generation and propagation along a chosen axis permits the study the local elastic anisotropy of myocardial muscle. As expected, myocardial elastic anisotropy is found to vary with muscle depth. The real time capabilities and potential of Shear Wave Imaging using ultrafast scanners for cardiac applications is finally illustrated by studying the dynamics of this fractional anisotropy during the cardiac cycle.

Influence of polysaccharide composition on the biocompatibility of pullulan/dextran-based hydrogels.

The implantation of a biomaterial for tissue engineering requires the presence of a suitable scaffold on which the tissue repair and regeneration will take place. Polymers have been frequently used for that purpose because they show similar properties to that of the natural extracellular matrix. Scaffold properties and biocompatibility are modulated by the composition of the polymers used. In this work four polysaccharide-based hydrogels (PSH) made of dextran and pullulan were synthesized. Their in vitro properties were determined and then tested in vivo in a rat model. As pullulan concentration increased in dextran hydrogels, the glass transition temperature and the maximum modulus decreased. In vitro degradation studies for 30 days demonstrated no significant degradation of PSH except for 100% pullulan hydrogel. In vivo tissue response evaluated 30 days after PSH subcutaneous implantation in rats indicated that all PSH were surrounded by a fibrous capsule. Adding pullulan to dextran induced an increased inflammatory reaction compared to PSH-D(100% dextran) or PSH-D(75)P(25)(75% dextran). This in vitro and in vivo data can be used in the design of hydrogels appropriate for tissue engineering applications.

An expansible aortic ring for a physiological approach to conservative aortic valve surgery.

OBJECTIVE: Dystrophic aortic insufficiency is characterized by dilation of the aortic annular base and sinotubular junction diameters preventing coaptation of thin and pliable cusps amenable to valve repair. An expansible aortic ring was designed to reduce dilated aortic root diameters to increase valvular coaptation height while maintaining root dynamics. The properties of the device were tested in vitro and in vivo in an ovine model. METHODS: Expansible rings were composed of an elastomer core covered by polyester fabric. After in vitro analysis of their mechanical properties, the rings were implanted in 6 sheep at both the level of the annular base and sinotubular junction (double subvalvular and supravalvular external aortic annuloplasty). Root dynamics were assessed by using intracardiac ultrasonography before surgical intervention and at 6 months. Histologic, scanning electron microscopic, and mechanical studies were then performed on explanted samples. RESULTS: The expansible ring produced a significant reduction of the aortic annular base and sinotubular junction diameters. Coaptation height was increased from 2.5 +/- 0.7 mm to 6.2 +/- 1.1 mm (P < .001). Mechanical testing on 6-month explanted samples revealed no significant differences in elastic modulus. Dynamics of the root were well preserved. Histomorphologic studies showed incorporation of the material without degradation. CONCLUSIONS: Expansible aortic ring implantation produces a significant annuloplasty that increases coaptation height while preserving the dynamics of the aortic root. The effectiveness of the device in treating aortic insufficiency is currently being evaluated in the prospective Conservative Aortic Valve surgery for aortic Insufficiency and Aneurysm of the Aortic Root trial comparing conservative aortic valve surgery versus mechanical valve replacement.

Treatment of atrial fibrillation by surgical epicardial ablation: bipolar radiofrequency versus cryoablation.

UNLABELLED: Atrial fibrillation is the most frequent form of cardiac arrhythmia. Its surgical management has improved in recent years with major advances in our knowledge of the underlying pathogenic mechanisms. This has led to simpler therapeutic strategies such as epicardial ablation. The aim of this comparative experimental study was to evaluate the efficacy of this treatment, achieved with either bipolar radiofrequency or cryoablation. MATERIALS AND METHODS: Twelve sheep were used. After left thoracotomy, epicardial ablation of the junction between the left pulmonary veins and the left atrium was achieved by means of bipolar radiofrequency in group A (n=6) and by cryoablation in group B (n=6). Electrical stimulation thresholds were determined before and after ablation. Four weeks after ablation, sheep were killed for pathologic studies. RESULTS: The mean stimulation threshold was 3.5+/-0.6 mA before ablation and 15.6+/-5.6 mA after ablation. The difference was significant in both groups, showing that effective conduction blockade was obtained with the two ablation methods. Histologic studies after radiofrequency and cryoablation showed limited coagulation necrosis and cellular rarefaction, respecting the supportive tissue. CONCLUSIONS: Both methods of surgical ablation by the epicardial route yielded effective electrical isolation of the pulmonary vein junction with the left atrium. This conduction blockade was due to limited coagulation necrosis with myocyte rarefaction, of similar extents in the two procedures. Standardization and refinement of this technique could extend the treatment indications for atrial fibrillation associated with other cardiac disorders that require surgical treatment without opening the left atrium.