Late results of double-valve replacement with biologic or mechanical prostheses.

BACKGROUND: We previously showed that the risk of reoperation for structural degeneration of bioprostheses was higher in cases involving patients older than 65 years (p = 0.003) and double-valve replacement (p = 0.02). The purpose of this study was to compare late outcome of mitral-aortic valve replacement using bioprostheses or mechanical valves. METHODS: The bioprosthesis group included all mainland France residents (n = 48) between 55 and 65 years old operated on between 1980 and 1995 for mitral-aortic valve replacement using bioprostheses. The mechanical valve group was obtained by matching each of these patients with a patient operated on using mechanical valves at approximately the same time during the study. RESULTS: In the bioprosthesis group, 10-year survival was 45%+/-8% versus 62%+/-7% in the mechanical valve group (not significant). The linearized reoperation rate was 6.8 per patient-year versus 1.1 per patient-year (p = 0.001), and the linearized reoperative mortality rate was 1.8 per patient-year and 0.7 per patient-year (not significant), respectively. CONCLUSIONS: The reoperative mortality risk after mitral-aortic valve replacement using two bioprostheses does not significantly decrease overall survival after age 65 years.

Clinical evaluation of heparin-coated circuits for routine coronary artery bypass grafting surgery: a prospective randomized study.

The aim of this study was to demonstrate the clinical and biological benefits of heparin-coated circuits in routine coronary artery bypass grafting (CABG). A prospective, randomized study was conducted in 80 patients undergoing routine CABG. Patients were randomized to either noncoated circuits (Group 1) or heparin-coated circuits (Group 2). A complete clinical evaluation was performed preoperatively at Days 0, 1, 2, and 3 and at discharge day and combined with extensive laboratory tests for hemostasis and inflammatory response. This study did not prove any major statistically significant clinical benefit of heparin-coated circuits in low risk patients. Postoperative bleeding, significantly less in the heparin-coated group, did not decrease significantly the number of transfused patients. Biological values were not changed significantly except for factor II and monocytes, which were higher in Group 2. Heparin-coated circuits offer minimal clinical and biological benefits for routine CABG surgery. However, they may prove beneficial for complex procedures or at-risk patients.

Late complications after prosthetic replacement of the ascending aorta: what did we learn from routine magnetic resonance imaging follow-up?

OBJECTIVE: Advances in surgical technique have improved early survival after surgery of the ascending aorta. However, follow-up data document serious late complications, mainly evolutive peri-prosthetic false aneurysms. Magnetic resonance imaging (MRI) has proved to be highly effective for monitoring these complications. This study evaluates 10 years of experience with routine MRI for follow-up. METHODS: Since January 1988, 114 patients with replacement of the ascending aorta either for type A acute dissection (group I, 45 patients) or aneurysms (group II, 69 patients) were followed up with annual MRI. Prosthetic replacement was either limited to supra-coronary ascending aorta (45%, 51/114) or extended to the aortic root and/or the aortic arch (55%). Biological glue was always utilized. MRI focused on peri-prosthetic haematoma, analyzing signal intensity changes and volume augmentation for early detection of false aneurysms, and on persistent residual dissection with or without evolutive aortic aneurysm distant to the prosthesis. RESULTS: Peri-prosthetic hematomas were almost equally found in both groups (26 (58%) in group I and 42 (61%) in group II) and were detected within the first year. Peri-prosthetic false aneurysms developed in 15 patients (group I, seven; group II, eight) as a complication of pre-existing hematomas and were indicated for elective reoperation. Forty-three (96%) of patients in group I had persistent residual dissection. Five patients in group I and two in group II needed reoperation for evolutive aortic aneurysm. In total, 22 of 114 (19%) patients were reoperated on during follow-up (12 (27%) in group I and ten (15%) in group II). Operative mortality was 13% (3/22). Freedom from reoperation at 1 year/5 years was: group I, 93%/84%; group II, 98%/88%. CONCLUSION: Peri-prosthetic haematoma occurs equally after aneurysm or dissection repairs and is a pre-existing condition for peri-prosthetic false aneurysm; biological glue or extended repair do not prevent late complications. Long-term MRI follow-up allows successful elective reoperation for life-threatened but asymptomatic patients.

Centrifugal pumps and heparin-coated circuits in surgical treatment of giant cerebral aneurysms.

Giant cerebral aneurysms may be untreatable by conventional neurosurgical techniques. Early attempts to use circulatory assistance and deep hypothermia were abandoned due to hemorrhagic complications. More recently, interest in circulatory support for complex neurosurgical procedures has been renewed. A consecutive series of 8 patients were operated on for giant cerebral aneurysms with the combined use of deep hypothermia. The protocol included careful preoperative cardiovascular assessment, perfect intraoperative synergy between neurosurgical and cardiac teams, minimally invasive peripheral vascular access including two femoral vein (21 F) and single arterial (17 F) femoral cannulation, use of total Carmeda coating on BioMedicus pumps in closed circuits, and reduced heparinization without Protamine reversal. All cerebral aneurysms were successfully treated through deep hypothermia (15-18 degrees C) as assessed by intraoperative fluoroscopic controls and Doppler vascular assessment. Mean circulatory support time was 174.2 +/- 29.6 min. Circulatory arrest period was 20 +/- 12 min. All patients survived and were extubated within 48 h. No major deficit was observed clinically or on postoperative CT scan. No hemorrhagic complications occurred (mean transfusions was 2.2 blood units). This work supports an extensive use of heparin-coated surfaces for complex circulatory assist techniques, either for cardiac or extra cardiac complex procedures.

Multiple valve replacement increases the risk of reoperation for structural degeneration of bioprostheses.

BACKGROUND AND AIM OF THE STUDY: The study aim was to analyze the results of reoperations for structural degeneration of bioprostheses, and to define a high-risk population for reoperative procedures. METHODS: A series of 524 consecutive patients who had undergone a first reoperative replacement for a failed bioprosthesis between 1978 and 1998 was reviewed retrospectively. The reoperative procedure comprised 363 single valve replacements, and 161 multiple valve replacements. During the original procedure, 648 bioprostheses had been implanted in the mitral (n = 403), aortic (n = 220) and tricuspid (n = 25) positions. RESULTS: The mean interval between the original procedure and reoperation was 8.8 +/- 3.3 years. Tissue valve failure was revealed by recurrence of cardiac insufficiency in 70% of cases. The overall early mortality rate was 8%, but early mortality rates for elective single mitral and aortic reoperative valve replacements were only 3.9% and 4%, respectively. Early mortality following reoperation for single and multiple valve replacement was 6.0% and 12.4% respectively (p = 0.02). Other significant multivariable predictors for early mortality were old age (p = 0.003), NYHA functional class (p = 0.007), presence of ascites (p = 0.02) and reoperation performed before 1988 (p = 0.013). CONCLUSIONS: The risk of reoperation for structural degeneration of bioprostheses is acceptable for elective single reoperative valve replacement as opposed to multiple reoperative valve replacement. This may limit the use of bioprostheses during the original procedure when multiple valve replacement is required.

Rescue revascularization for acute coronary occlusion late after radiotherapy.

Because radiation-induced coronary artery stenoses are frequently severe and located proximally, some patients are admitted in emergency. This report describes the case of a 47-year-old woman with radiation-induced stenosis of the left main coronary artery who presented with cardiac arrest during angiography. The patient was successfully treated using circulatory assistance and percutaneous transluminal coronary angioplasty as a bridge to coronary artery bypass grafting.

Study of left ventricular bypass using Wankel type semipulsatile blood pump.

The influence of the Wankel type semipulsatile left ventricular assistance on hemodynamics was investigated with a computer simulation and an animal experiment. A simulation circuit was constructed to express the circulatory system. A current source was added to create a semipulsatile blood pump. The left and right ventricles were replaced by variable compliances. Left heart failure was simulated by decreasing the amount of compliance change of the left ventricle. Under the condition of heart failure when semipulsatile assist flow increased, the mean aortic pressure (AoP), tension time index (TTI), and diastolic pressure time index (DPTI) increased, and the cardiac output, pulse pressure (PP), and pulsatility indicator (PI) decreased. In an animal experiment, a Wankel type blood pump was used in a calf. With the increase of the assist flow, AoP curves became less pulsatile, and PP and PI decreased in accordance, which was predicted by the numerical simulation.

Dynamic aortomyoplasty: clinical experience and thoracoscopic surgery feasibility study.

BACKGROUND: Surgical procedures using the latissimus dorsi (LD) muscle to assist chronic heart failure inflict major trauma on severely sick patients. A less invasive approach may prove beneficial. The aim of this article is to review our clinical and experimental approaches of dynamic aortomyoplasty (AMP) and emphasize the necessity to reorient surgical technique towards new directions and a less invasive thoracoscopic approach. MATERIALS AND METHODS: A clinical pilot study on dynamic descending AMP started in June 1995 and included four patients. Two of them could benefit from LD counterpulsation, surviving 6 months and 18 months. Following this clinical experience, we investigated, on an animal model, minimally invasive thoracoscopic surgery for this procedure. Twelve goats underwent endoscopic LD harvest and video-assisted aortic wrap, and were studied after surgical recovery from an anatomical and functional standpoint. RESULTS: Clinical AMP using open techniques provided extraaortic counterpulsation in NYHA Class IV patients contraindicated for other surgical therapies. However, surgical technique and strategy needed improvements for optimal cardiac assistance and better patient outcome. Minimally invasive thoracoscopic surgery was feasible and reproducible in goats, achieving improved anatomy and physiology as compared to the open technique in humans. When appropriate the wrapping technique and stimulation protocol were used, an optimal counterpulsation was demonstrated. We concluded that thoracoscopic AMP may provide a minimally invasive approach to cardiac assistance and thus, a new surgical option for patients presenting with chronic heart failure.

Cora rotary pump for implantable left ventricular assist device: biomaterial aspects.

Our group is developing a left ventricular assist device based on the principle of the Maillard-Wankel rotative compressor: it is a rotary, not centrifugal, pump that produces a pulsatile flow. Stringent requirements have been defined for construction materials. They must be light, yet sufficiently hard and rigid, and able to be machined with high precision. The friction coefficient must be low and the wear resistance high. The materials must be chemically inert and not deformable. Also, the materials must be biocompatible, and the blood contacting surface must be hemocompatible. We assessed the materials in terms of physiochemistry, mechanics, and tribology to select the best for hemocompatibility (determined by studies of protein adsorption; platelet, leukocyte, and red cell retention; and hemolysis, among other measurements) and biocompatibility (determined by measurement of complement activation and toxicity, among other criteria). Of the materials tested, for short- and middle-term assistance, we chose titanium alloy (Ti6Al4V) and alumina ceramic (Al2O3) and for long-term and permanent use, composite materials (TiN coating on graphite). We saw that the polishing process of the substrate must be improved. For the future, the best coating material would be diamond-like carbon (DLC) or crystalline diamond coating.

Physico-chemistry and cytotoxicity of ceramics: part I: characterization of ceramic powders.

The morphology of Al2O3, ZrO2/Y2O3, AIN, B4C, BN, SiC, Si3N4, TiB2, TiC, TiN ceramic, graphite and diamond powders has been studied by scanning electron microscopy (SEM) and the specific area of each powder was determined with the BET method. X-ray diffraction (XRD) investigations have been carried out in order to evaluate the crystallinity and determine the constitutive phases. The chemical composition was assessed by classical chemical analyses and by X-ray microprobe; some powders were studied by the laser micro-Raman technique. Correlations have been established between all these results.

Bone mineral density in patients given oral vitamin K antagonists.

BACKGROUND: Divergent results have been obtained in studies of bone mineral density in patients under oral vitamin K antagonists. OBJECTIVE: To gather prospective data on bone mineral density and bone metabolism in 70 aortic valve replacement patients. STUDY DESIGN: 49 patients who had been under oral vitamin K antagonists for at least one year after implantation of a mechanical aortic valve were compared with 21 recipients of a tissue aortic valve that did not require anticoagulant therapy. The following investigations were done in all patients: (1) dual-energy X-ray absorptiometry measurement of bone mineral density at the lumbar spine and femoral neck; (2) roentgenograms of the spine and pelvis; (3) serum assays of calcium, phosphate, creatinine, alkaline phosphatase, osteocalcin, 25-OH-vitamin D3, and parathyroid hormone. RESULTS: The two groups were comparable regarding age and sex ratio. No differences were found in lumbar or femoral neck bone mineral density even after adjustment for age and sex. A trend toward an increase in bone mineral density at both sites with increasing duration of vitamin K antagonist therapy was demonstrated. The only bone turnover marker difference between the two groups was a significantly lower serum osteocalcin level in the group under vitamin K antagonist therapy (P < 0.0001). CONCLUSIONS: Long-term vitamin K antagonist therapy does not affect bone mineral density at the lumbar spine or femoral neck and also fails to modify bone turnover markers, with the exception of osteocalcin.

Aortic valve or root replacement with cryopreserved homograft for active infectious endocarditis.

Active aortic endocarditis is a serious condition that carries a high mortality and morbidity. The aim of this study was to analyse results obtained from 24 patients who underwent aortic valve or root replacement with cryopreserved homograft for aortic endocarditis. Eleven patients had native valve endocarditis, and 13 had prosthetic valve endocarditis. The mean age was 47.7 years: there were seven women and 17 men. Causative organisms were staphylococci (12), streptococci (four), serratia (one), candida (one), pneumococci (one), while no organisms were isolated in the remaining five patients. Complete reconstruction of the aortic annulus with homograft conduits was necessary in 20 patients (six total root and 14 mini-root). Infracoronary homograft aortic valve replacement was performed in the remaining patients. One patient died 1 day after the operation from ventricular failure, and two others died after 4 and 6 months as a result of arrhythmia. One patient died of recurrent endocarditis 1 year after surgery. The actuarial survival rate at 3 years was 83.4%. All survivors are symptom-free, with no evidence of recurrent endocarditis. Doppler echocardiography showed minimal aortic regurgitation in four patients.

Biological evaluation of mechanical circulatory support systems in calves.

Data from animal experiments with mechanical circulatory support systems (MCSS) performed in Groningen and Marseille over the past years were used to obtain normal values of hematological, coagulation, rheological and blood chemistry parameters in calves. These parameters were divided between two groups: a limited number of parameters necessary to assess biocompatibility properties of MCSS quickly and a more extensive number of parameters suitable for more detailed biological evaluation of blood pumps. All applied tests can be examined in calf blood as well as in human blood. Parameters were selected on clinical relevance and usefulness for standardization procedures. The obtained data were compared with normal values in human beings derived from the literature.