Hendrik T. Tevaearai

Ten-year comparison of pericardial tissue valves versus mechanical prostheses for aortic valve replacement in patients younger than 60 years of age.

OBJECTIVE Aortic valve replacement using a tissue valve is controversial for patients younger than 60 years old. The long-term survival in this age group, the expected event rates during long-term follow-up, and valve-related complications are not clearly determined. METHODS From January 2000 to December 2009, overall survival, valve-related events, and echocardiographic outcomes were analyzed in all patients younger than 60 years of age, who underwent biologic aortic valve replacement. Patients who received a Perimount Carpentier-Edwards pericardial tissue valve (n = 103) were selected and compared with a propensity matched group of 103 patients who received aortic valve replacement using a mechanical bileaflet valve. The mean follow-up was 33 ± 24 months (range, 2-120), and the mean age at implantation was 50.6 ± 8.8 years (bioprosthesis, 55 ± 8.9 years; mechanical valve, 50 ± 8.6 years; P = .03). RESULTS Survival was significantly reduced in patients after biologic aortic valve replacement (90.3% vs 98%; P = .038). Freedom from all valve-related complications (bioprosthesis, 54.5%; mechanical valve, 51.6%; P = NS) and freedom from reoperation (bioprostheses, 100%; mechanical valve, 98%; P = NS) were comparable in both groups. The average transvalvular mean (11.2 ± 4.2 mm Hg vs 10.5 ± 6.0 mm Hg, P = .05) and peak (19.9 ± 6.7 mm Hg vs 16.7 ± 8.0 mm Hg, P = .03) gradients were greater after biologic aortic valve replacement. Regression of the left ventricular mass index was more pronounced after mechanical valve replacement (118.5 ± 24.9 g/m(2) vs 126.5 ± 38.5 g/m(2); P = NS). The echocardiographic patient-prosthesis mismatch was greater at follow-up after biological aortic valve replacement (0.876 ± 0.2 cm(2)/m(2) vs 1.11 ± 0.4 cm(2)/m(2); P = .01). Oral anticoagulation was a protective factor for survival among the bioprosthetic valve patients (P = .024). CONCLUSIONS In the present limited cohort of patients younger than 60 years old, biologic aortic valve replacement was associated with reduced mid-term survival compared with survival after mechanical aortic valve replacement. Despite similar valve-related event rates in both groups, the better hemodynamic performance of the mechanical valves and/or protective effect of oral anticoagulation seemed to improve the outcome. The transcatheter valve-in-valve intervention as potential treatment of tissue valve degeneration should not be considered the sole bailout strategy for younger patients because no evidence is available that this would improve the outcome.

Hydrogel-based engineered skeletal muscle grafts normalize heart function early after myocardial infarction

Tissue engineering represents an attractive approach for the treatment of congestive heart failure. The influence of the differentiation of myogenic graft for functional recovery is not defined. We engineered a biodegradable skeletal muscle graft (ESMG) tissue and investigated its functional effect after implantation on the epicardium of an infarcted heart segment. ESMGs were synthesized by mixing collagen (2 mg/mL), Matrigel (2 mg/mL), and rat skeletal muscle cells (10(6)). Qualitative and quantitative aspects of ESMGs were optimized. Two weeks following coronary ligation, the animals were randomized in three groups: ESMG glued to the epicardial surface with fibrin (ESMG, n = 7), fibrin alone (fibrin, n = 5), or sham operation (sham, n = 4). Echocardiography, histology, and immunostaining were performed 4 weeks later. A cohesive three-dimensional tissular structure formed in vitro within 1 week. Myoblasts differentiated into randomly oriented myotubes. Four weeks postimplantation, ESMGs were vascularized and invaded by granulation tissue. Mean fractional shortening (FS) was, however, significantly increased in the ESMG group as compared with preimplantation values (42 +/- 6 vs. 33 +/- 5%, P < 0.05) and reached the values of controlled noninfarcted animals (control, n = 5; 45 +/- 3%; not significant). Pre- and postimplantation FS did not change over these 4 weeks in the sham group and the fibrin-treated animals. This study showed that it is possible to improve systolic heart function following myocardial infarction through implantation of differentiated muscle fibers seeded on a gel-type scaffold despite a low rate of survival.

Minimally invasive harvest of the saphenous vein for coronary artery bypass grafting

BACKGROUND Preparation of the great saphenous vein for coronary artery bypass grafts is traditionally performed through one or many long cutaneous incisions. We describe the dissection of the great saphenous vein through small cutaneous incisions using the Mini Harvest System. METHODS The device is composed of a retractor coupled to a light source. Introduced under the skin, above the anterior plane of the vein, it allows an easy preparation of the vein under direct vision. The entire vein can be dissected from the ankle to the groin through sequential cutaneous incisions along the leg. A prospective, randomized trial was performed to compare the minimally invasive vein harvest technique (group 1, n = 15) versus the standard method (group 2, n = 15). RESULTS In addition to an internal mammary artery graft, 28 venous coronary bypass grafts were performed in group 1 (mean, 1.9 +/- 1.0) and 32 in group 2 (mean, 2.1 +/- 1.0). The mean cutaneous incision length divided by the mean length of the harvested vein was 10.8 cm/32.3 cm = 33% for group 1 and 37.6 cm/33.2 cm = 113% in group 2 (p < 0.001). Wounds were examined daily and a final assessment was performed on day 7. Better cicatrization, less hematoma and edema, and less pain were observed in group 1. CONCLUSIONS Minimally invasive harvest of the great saphenous vein offers many advantages over the traditional harvest method. Besides the aesthetic aspect, healing is better and postoperative discomfort is reduced.

Fine-tuning of substrate architecture and surface chemistry promotes muscle tissue development

Tissue engineering has been increasingly brought to the scientific spotlight in response to the tremendous demand for regeneration, restoration or substitution of skeletal or cardiac muscle after traumatic injury, tumour ablation or myocardial infarction. In vitro generation of a highly organized and contractile muscle tissue, however, crucially depends on an appropriate design of the cell culture substrate. The present work evaluated the impact of substrate properties, in particular morphology, chemical surface composition and mechanical properties, on muscle cell fate. To this end, aligned and randomly oriented micron (3.3±0.8 μm) or nano (237±98 nm) scaled fibrous poly(ε-caprolactone) non-wovens were processed by electrospinning. A nanometer-thick oxygen functional hydrocarbon coating was deposited by a radio frequency plasma process. C2C12 muscle cells were grown on pure and as-functionalized substrates and analysed for viability, proliferation, spatial orientation, differentiation and contractility. Cell orientation has been shown to depend strongly on substrate architecture, being most pronounced on micron-scaled parallel-oriented fibres. Oxygen functional hydrocarbons, representing stable, non-immunogenic surface groups, were identified as strong triggers for myotube differentiation. Accordingly, the highest myotube density (28±15% of total substrate area), sarcomeric striation and contractility were found on plasma-coated substrates. The current study highlights the manifold material characteristics to be addressed during the substrate design process and provides insight into processes to improve bio-interfaces.

Impact of duration of chest tube drainage on pain after cardiac surgery

OBJECTIVE This study was designed to analyze the duration of chest tube drainage on pain intensity and distribution after cardiac surgery. METHODS Two groups of 80 cardiac surgery adult patients, operated on in two different hospitals, by the same group of cardiac surgeons, and with similar postoperative strategies, were compared. However, in one hospital (long drainage group), a conservative policy was adopted with the removal the chest tubes by postoperative day (POD) 2 or 3, while in the second hospital (short drainage group), all the drains were usually removed on POD 1. RESULTS There was a trend toward less pain in the short drainage group, with a statistically significant difference on POD 2 (P=0.047). There were less patients without pain on POD 3 in the long drainage group (P=0. 01). The areas corresponding to the tract of the pleural tube, namely the epigastric area, the left basis of the thorax, and the left shoulder were more often involved in the long drainage group. There were three pneumonias in each group and no patient required repeated drainage. CONCLUSIONS A policy of early chest drain ablation limits pain sensation and simplifies nursing care, without increasing the need for repeated pleural puncture. Therefore, a policy of short drainage after cardiac surgery should be recommended.

Long-term results of mitral-aortic valve operations

OBJECTIVE We analyzed the long-term morbidity and mortality of our experience with combined mitral-aortic surgery, as well as their determinants. METHODS Among 2109 consecutive patients undergoing valve operations, 200 had mitral-aortic valve procedures with at least implantation of a mechanical prosthesis: 163 of 200 (81.5%) patients had double valve replacement and 37 of 200 (18.5%) had mitral valve repair and aortic valve replacement. All mechanical valves were bileaflet prostheses. Preoperatively, 171 of 200 (85.5%) patients were in New York Heart Association class III-IV. Event-free survivals were determined by means of the Kaplan-Meier method and determinants of survivals with the Cox proportional hazards model (p < 0.05) entering 39 preoperative and perioperative factors. Follow-up was complete for 96% of the patients (192/200). RESULTS Overall survivals at 5, 10, and 15 years were 88.5% +/- 0.55%, 73.5% +/- 4%, and 53.3% +/- 8.9%, and rates of freedom from valve-related mortality were 92.9% +/- 1.5%, 85.8% +/- 3.5%, and 85.8% +/- 3.5%. The rates of freedom from permanent valve-related impairment were 91.5% +/- 1.7%, 85.4% +/- 3.5%, and 79.3% +/- 6.7%, and those from all valve-related mortality and morbidity were 74.1% +/- 2.3%, 53.8% +/- 5%, and 49% +/- 5.6%. At last follow-up, 90% (139/154) of the survivors were in New York Heart Association class I-II. Left ventricular ejection fraction less than 50%, age older than 70 years, and preoperative ventricular arrhythmias were independent risk factors for valve-related late deaths. Diabetes, ejection fraction less than 50%, and coronary artery disease were independent determinants of all valve-related events. CONCLUSIONS Functional results of survivors of combined mitral-aortic surgery are excellent. However long-term valve-related morbidity and mortality are substantial. In the patient population studied, the predictors are determined by patient-related factors, mainly myocardial factors, but not by valve-related factors.

Drawback of aortoplasty for aneurysm of the ascending aorta associated with aortic valve disease.

BACKGROUND Aortoplasty has been advocated for moderate dilatation of the ascending aorta associated with aortic valve disease. We report our results with this conservative approach. METHODS Seventeen consecutive patients with unsupported aortoplasty were reviewed. Twelve patients had aortic valve regurgitation and 5 had stenosis. The aortic wall was analyzed histologically in 14 patients. Follow-up was complete, with a mean time of 6 years (range, 2.3 to 10.5 years). RESULTS Two patients among the 15 hospital survivors died during follow-up of causes unrelated to aortic pathology. Survival at 7 years was 86.7% (+/- 8.8%). Recurring aortic aneurysms developed in 4 patients after a mean time of 63 months, with an event-free survival at 7 years of 41% (+/- 21%). All of these 4 patients had aortic valve regurgitation and cystic medial necrosis. CONCLUSIONS The recurrence rate of aneurysms after unsupported aortoplasty and aortic valve replacement is high in patients with aortic regurgitation. This strongly suggests that in these patients, the aortic dilatation is related to an underlying wall deficiency, associated with the aortic valve pathology, rather than to the hemodynamic stress imposed by the aortic valve disease.

Endovascular suitability and outcome after open surgery for ruptured abdominal aortic aneurysm

Endovascular repair of ruptured abdominal aortic aneurysm (rAAA) has rapidly gained popularity, but superior results may be biased by patient selection. The aim was to investigate whether suitability for endovascular repair predicted survival, irrespective of technique of repair.

In Vivo Electroporation Mediated Gene Delivery to the Beating Heart

Gene therapy may represent a promising alternative strategy for cardiac muscle regeneration. In vivo electroporation, a physical method of gene transfer, has recently evolved as an efficient method for gene transfer. In the current study, we investigated the efficiency and safety of a protocol involving in vivo electroporation for gene transfer to the beating heart. Adult male rats were anesthetised and the heart exposed through a left thoracotomy. Naked plasmid DNA was injected retrograde into the transiently occluded coronary sinus before the electric pulses were applied. Animals were sacrificed at specific time points and gene expression was detected. Results were compared to the group of animals where no electric pulses were applied. No post-procedure arrhythmia was observed. Left ventricular function was temporarily altered only in the group were high pulses were applied; CK-MB (Creatine kinase) and TNT (Troponin T) were also altered only in this group. Histology showed no signs of toxicity. Gene expression was highest at day one. Our results provide evidence that in vivo electroporation with an optimized protocol is a safe and effective tool for nonviral gene delivery to the beating heart. This method may be promising for clinical settings especially for perioperative gene delivery.

Covalent immobilisation of VEGF on plasma-coated electrospun scaffolds for tissue engineering applications.

Recent findings in the field of biomaterials and tissue engineering provide evidence that surface immobilised growth factors display enhanced stability and induce prolonged function. Cell response can be regulated by material properties and at the site of interest. To this end, we developed scaffolds with covalently bound vascular endothelial growth factor (VEGF) and evaluated their mitogenic effect on endothelial cells in vitro. Nano- (254±133 nm) or micro-fibrous (4.0±0.4 μm) poly(ɛ-caprolactone) (PCL) non-wovens were produced by electrospinning and coated in a radio frequency (RF) plasma process to induce an oxygen functional hydrocarbon layer. Implemented carboxylic acid groups were converted into amine-reactive esters and covalently coupled to VEGF by forming stable amide bonds (standard EDC/NHS chemistry). Substrates were analysed by X-ray photoelectron spectroscopy (XPS), enzyme-linked immuno-assays (ELISA) and immunohistochemistry (anti-VEGF antibody and VEGF-R2 binding). Depending on the reaction conditions, immobilised VEGF was present at 127±47 ng to 941±199 ng per substrate (6mm diameter; concentrations of 4.5 ng mm(-2) or 33.3 ng mm(-2), respectively). Immunohistochemistry provided evidence for biological integrity of immobilised VEGF. Endothelial cell number of primary endothelial cells or immortalised endothelial cells were significantly enhanced on VEGF-functionalised scaffolds compared to native PCL scaffolds. This indicates a sustained activity of immobilised VEGF over a culture period of nine days. We present a versatile method for the fabrication of growth factor-loaded scaffolds at specific concentrations.