Correlation between structural changes and acute thrombogenicity in transcatheter pericardium valves after crimping and balloon deployment.

INTRODUCTION: Transcathether heart valve replacement has gained considerable acceptance during the last decades. It is now part of the armamentarium for aortic valve replacement. The procedure proved to be highly efficient. However the issues of the blood compatibility and tissue durability were not raised and the adverse events were probably under-reported, according to observations of thrombosis after deployment. MATERIAL AND METHOD: Bovine pericardium leaflets were sewn inside a 26mm diameter stainless steel stent to manufacture these valves (one control and two experimental). The correlation between the trauma and the acute thombogenicity of bovine pericardium leaflets, after crimping and ballooning, was investigated via an in vitro blood flow with labeled platelets. These leaflets were processed for histology: scanning electron microscopy, light microscopy, and transmission electron microscopy. RESULTS: The control specimens showed a regular pericardium structure with some blood cells deposited on the collagen fibrous surface (inflow) and scarce blood cells deposited on the serous surface (outflow). After crimping and ballooning, the structure of the pericardium was severely injured, eventually with delaminations and ruptures. The blood cell uptake was considerably increased compared to the control. CONCLUSION: It would therefore be appropriate to pay more attention to the design of the valves. Specifically, the incorporation of a buffer tissue or fabric between the pericardium and the metallic stent is suggested. The issue of ballooning deserves detailed and in depth investigation regarding the lifetime of the device.

Transcatheter heart valve crimping and the protecting effects of a polyester cuff.

INTRODUCTION: Prior to deployment, the percutaneous heart valves must be crimped and loaded into sheaths of diameters that can be as low as 6mm for a 23mm diameter valve. However, as the valve leaflets are fragile, any damage caused during this crimping process may contribute to reducing its long-term durability in vivo. MATERIAL AND METHOD: Bovine pericardium percutaneous valves were manufactured as follows. The leaflets were sutured on a nitinol frame. A polyester cuff fabric served as a buffer between the pericardium and the stent. Two valves were crimped and one valve was used as control. The valves were examined in gross observation and micro-CT scan and then the leaflets were processed for histology and analyzed in scanning electron microscopy, light microscopy and transmission electron microscopy. RESULT: Crimping of the valves resulted in the increase thickness of the leaflets and there was no evidence of additional delamination. The heavy prints of the stents were irregularly distributed on the outflow surface in the crimped devices and were shallow and did not penetrate throughout the thickness of the leaflets. However, the wavy microscopy of collagen fiber bundles was well preserved. They were found to remain individualized without any agglutination as shown by the regular banding appearance. CONCLUSION: Crimping of self-deployable valves per se caused only minor damages to the leaflets. However, the procedure could be refined in order to minimize areas of high pressure and swelling of the tissue that can be accompanied with flow surface disruption and increase of the hydraulic conductance. The incorporation of a polyester buffer serves to prevent the deleterious effects that may be caused if the pericardium tissue were in direct contact with the nitinol stent.

[Systolic anterior motion (SAM): a rare cause of late failure in mitral valve repair]. / Le SAM: une cause exceptionnelle d'echec tardif de plastie mitrale.

Systolic anterior motion (SAM) of the mitral valve is a rare complication of mitral valve repair. The treatment of the large majority of cases is purely medical. Nevertheless, an early degradation may require reoperation (revision of the repair or valve replacement). The authors report two cases of post-repair SAM with a poor outcome with medical therapy which required reoperation after several years. In both cases, an excess of bivalvular tissue with respect to the size of the mitral orifice was observed. A second repair was possible (sliding valvuloplasty associated with an oval resection of the anterior leaflet) with satisfactory long-term results. The identification of the risk factors and careful analysis of the lesions in cases of SAM after mitral valve repair may lead to a repeat repair and the avoidance of mitral valve replacement.

Exhaled carbon monoxide in mechanically ventilated critically ill patients: influence of inspired oxygen fraction.

OBJECTIVE: To assess the feasibility of exhaled carbon monoxide (CO) measurements in mechanically ventilated critically ill adult patients and to determine the influence of inspired oxygen fraction on this measurement. DESIGN: Prospective physiologic study. SETTING: Medical ICU in a community hospital. PATIENTS: The study was performed on nine mechanically ventilated patients with varying diagnoses. MEASUREMENTS AND RESULTS: Carbon monoxide concentration was determined with an infrared CO analyzer on exhaled breath collected at the outlet of the ventilator. We assessed the stability of exhaled carbon monoxide concentration over a 4-hour period and determined its course during a 7-hour period after inspired oxygen fraction had been abruptly increased from baseline to 1. Carbon monoxide was detected in exhaled breath in each patient at a higher concentration than in inspired gas (0.64 +/- 0.1 ppm vs 0.25 ppm, approximately). Exhaled carbon monoxide did not vary during a 4-hour period in five hemodynamically stable patients. When inspired oxygen fraction was increased from baseline (0.52 +/- 0.04) to 1, exhaled carbon monoxide concentration increased abruptly from baseline (0.63 +/- 0.13 ppm) to a peak value of 1.54 +/- 0.16 ppm within 15 min and returned slowly to baseline values within 7 h. CONCLUSION: CO was easily detected in the exhaled breath of mechanically ventilated patients and CO lung excretion was markedly but transiently dependent on inspired oxygen fraction. Other studies are warranted in order to determine the different factors that might influence CO lung excretion in critically ill patients.

Videothoracoscopic lung biopsy in diffuse infiltrative lung diseases: a 5-year surgical experience.

BACKGROUND: To establish an accurate diagnosis of diffuse infiltrative lung disease, a surgical lung biopsy may be required. We report our experience with video-thoracoscopic lung biopsy over a period of 5 years. METHODS: From March 1992 through December 1996, videothoracoscopic lung biopsy was performed in 64 patients (17 were women [26.5%]; age, 50.5+/-13 years) with a diagnosis of diffuse infiltrative lung disease of an unknown cause. All patients except one received general anesthesia. Single lung ventilation was used in 61 patients. All lung biopsies were obtained with an endoscopic stapler. RESULTS: Single lung biopsies were performed in 39 patients (61%), two biopsies in 23 patients (36%), and three biopsies in 2 patients. Minithoracotomies were necessary in 10 patients (15.6%) owing to an iatrogenic pulmonary wound (1 patient), extensive pleural adhesions (6 patients), and a stiff lung (3 patients). Postoperative complications were rare and included five discrete pneumothoraces (7.8%), all resolving spontaneously, one prolonged air leak (1.6%), and one hemothorax requiring reoperation. Three preoperatively debilitated patients died (4.7%), 2 with progression of respiratory failure and 1 owing to septic shock. Average chest tube duration was 2.4+/-2 days and average hospital stay was 4.6+/-2.5 days. Lung biopsy contributed to the diagnosis in 59 patients (92%). CONCLUSIONS: Videothoracoscopic lung biopsy using an endoscopic stapler is a safe and effective procedure in most cases and should be performed by trained thoracic surgeons.

Does glutaraldehyde induce calcification of bioprosthetic tissues?

BACKGROUND: Glutaraldehyde has been said to be responsible in part for the calcification of glutaraldehyde-treated tissues after implantation in animals or humans. We investigated whether the origin of the tissue, autologous or heterologous, could have a more prominent role in the process of calcification. METHODS: Three-month-old sheep received sheep pericardial samples (n = 133) and human pericardial samples (n = 123) implanted subcutaneously. Samples were treated with 0.6% glutaraldehyde for 5, 10, or 20 minutes or 7 days and then rinsed thoroughly before implantation. Samples were then retrieved after 3 months. Calcium content was assessed by spectrophometry. RESULTS: The results show a low calcium content in the autologous group (mean 1.14+/-2.07) and a high calcium content in the heterologous group (mean 38.97+/-26). These results were the same regardless of the duration of the treatment. CONCLUSIONS: Glutaraldehyde treatment (0.6%) does not play a significant role in the calcification of glutaraldehyde-treated tissue regardless of the origin, autologous or heterologous, of the tissue. Glutaraldehyde-treated autologous tissues are associated with an incidence of calcification lower than heterologous tissues.

Is 10 minutes the optimum immersion time in 0.6% glutaraldehyde for human pericardium?

BACKGROUND AND AIM OF THE STUDY: Pericardial fixation with 0.6% glutaraldehyde is usually assessed by measuring the shrinkage temperature of the tissue: the higher the shrinkage temperature, the greater the degree of cross-linking induced between collagen molecules. Animal pericardium studies have shown maximum response to be obtained after brief immersion (10 min). Our aim was to evaluate the effect of glutaraldehyde immersion time on shrinkage temperature of human pericardium which, to our knowledge, has not yet been studied. METHODS: Pericardial strips were harvested from 40 patients undergoing cardiac surgery. Time of immersion in glutaraldehyde ranged from 3 min to 6 months. Fresh untreated human pericardium samples were used as controls. The relationship between shrinkage temperature and time of treatment with glutaraldehyde was studied using a regression analysis. RESULTS: Glutaraldehyde treatment of pericardial tissues caused an increase in shrinkage temperature that was related biphasically to the time of immersion in glutaraldehyde. Mathematical expression of this curve permitted glutaraldehyde immersion time to be evaluated in relation to the degree of optimal shrinkage temperature. The time required for optimal fixation with glutaraldehyde, as measured by shrinkage temperature, was 100+/-0.77 min. CONCLUSION: Our results suggested that a 10-min exposure to glutaraldehyde was insufficient for 'correct' fixation of human pericardium. Inadequate glutaraldehyde exposure of human pericardium may explain mid and long-term failures reported with this tissue in cardiac surgery.

Autologous pericardial patch harvesting site for cardiac valve repair: anatomic and morphometric considerations.

BACKGROUND AND AIMS OF THE STUDY: Short-term glutaraldehyde-fixed autologous pericardium is widely used in cardiac valve repair or in autologous pericardial bioprosthesis construction. The thinner the tissue, the better the fixation. The aim of this study was to determine thickness and useful surface area of pericardium in relation to harvesting site using a digital thickness counter (0.01 mm precision). METHODS: Parietal pericardium fragments were obtained from the pericardial sac of six fresh cadavers (group I). In the other groups, pericardial strips (80 x 30 mm) were obtained from patients undergoing surgery: group II patients (n = 5 females) and group III (n = 10 males) were non-cardiomegalic (cardiothoracic ratio (CTR)<0.5), while group IV patients (n = 5) were all cardiomegalic (CTR >0.5). RESULTS: Results were reported on a coloric scale according to measurement position. In group I, mean surface area was 93+/-18 cm2, and thickness gradually increased from 0.1 to 0.6 mm, maximally on the diaphragm, along the left heart side. In other groups, a gradual increase in thickness was identified towards the diaphragmatic zone. Significant differences in tissue thickness appear as a result of cardiomegaly, but are not related to the sex of the patients. CONCLUSIONS: Pericardium taken from the right anterior aspect of the pericardial sac in patients without cardiomegaly is the most appropriate tissue for valve reconstructive surgery, due to its thin nature and hence better fixation properties.

Mechanical modifications to human pericardium after a brief immersion in 0.625% glutaraldehyde.

BACKGROUND AND AIMS OF THE STUDY: The use of human pericardium pretreated for 10 min with 0.625% glutaraldehyde (GLUT) in valvular repair or intracardiac reconstruction has produced good results. However, to date, no investigations have been made to determine the mechanical changes that occur in the tissue following such pretreatment. METHODS: Human pericardial samples were harvested from 25 patients and immersed in GLUT for increasing times (5, 10, 30, 60 min and 6 months). Either untreated human pericardium or bovine pericardium treated for six months with GLUT served as controls. Tensile tests were performed with a uniaxial load machine and a pulsative bench. Fatigue testing was for 14 days; each sample was tested at 1,200 cycles/min at a controlled pressure of 90-120 mmHg. RESULTS: Untreated tissue thickness was 0.44+/-0.16 mm, but after six months GLUT treatment it was 0.53+/-0.15 mm (p<0.001). There was a 13.7% shrinkage of tissue after six months immersion. Strain was significantly greater in treated tissue than in untreated tissue, while stiffness decreased with the duration of GLUT immersion. Young's modulus was significantly lower after six months GLUT treatment (0.26+/-0.06 MPa) compared with untreated, and 5-, 10- and 30-min GLUT treatment (0.32+/-0.15, 0.35+/-0.09, 0.32+/-0.09 and 0.36+/-0.10 MPa (p<0.05)), respectively. Creep was greater after six months GLUT treatment (0.5+/-0.03%) than in untreated and 10-, 30- and 60-min treatments (0.3+/-0.50, 0.27+/-0.01, 0.27+/-0.02, 0.3+/-0.01% (p<0.05)), respectively. Ultimate tensile stress (UTS) was greater in 10-min treated pericardium than in untreated tissue: 38.46+/-11.75 versus 22.17+/-8.30 MPa (p<0.05) respectively. Strain at rupture was greater in the 6-month group (30.62+/-2.54%) than for untreated and 10-, 30- and 60-min GLUT immersion 16.3+/-0.73, 21.85+/-0.75, 20.12+/-1.04 and 18.87+/-0.86% (p<0.05), respectively. Fatigue testing showed an increased length after five and 10 min, and six months, with a lengthening of 14.66, 12.53, 7.66%, respectively compared with 3.5% for untreated tissue (p<0.05). There were three failures in the untreated group (n = 5), none in the 5- and 10-min groups, and one in the 6-month group (p<0.05). CONCLUSION: Brief immersion of human pericardial tissue in 0.625% glutaraldehyde reduces the tissue's stiffness and improves its durability for use in cardiac surgery.

Aortic valve surgery in osteogenesis imperfecta: report of two cases and review of the literature.

Aortic insufficiency is a well known but uncommon valvular dysfunction in patients with osteogenesis imperfecta. In such cases, aortic valve surgery has rarely been performed, and carries a high risk of perioperative complications. We report two patients with osteogenesis imperfecta, who underwent elective successful aortic valve replacement. The surgical problems encountered in this connective tissue disorder are also reviewed.

Tricuspid bioprosthesis replacement with cryopreserved mitral homograft.

We report the case of replacement of a dysfunctional tricuspid Hancock bioprosthesis by a cryopreserved mitral homograft. Tricuspid bioprosthesis was approached on a beating heart. The mitral homograft was orientated so as the anatomic anterior leaflets corresponding and a semi rigid prosthetic ring was inserted. At 1 year follow-up, the patient's clinical condition and echocardiographic results were satisfactory.

Dynamic cardiomyoplasty: clinical follow-up at 12 years.

OBJECTIVE: The purpose of this study is to evaluate the long-term outcome of dynamic cardiomyoplasty. This surgical technique was conceived to assist the failing heart. The many proposed mechanisms of action of cardiomyoplasty are: (1) systolic assist; (2) limitation of ventricular dilation; (3) reduction of ventricular wall stress (sparing effect); (4) ventricular remodeling with an active girdling effect; (5) angiogenesis; and (6) a neurohumoral effect. METHODS: We investigated 95 patients in our hospital undergoing this procedure due to severe chronic heart failure, refractory to optimal medical treatment. Patients had a mean age of 51 +/- 12 years. The etiology of heart failure was ischemic 55%, idiopathic 34%, ventricular tumor 6%, and other 5%. The mean follow-up was 44 months. RESULTS: The mean New York Heart Association (NYHA) functional class improved postoperatively from 3.2 to 1.8. Average radioisotopic left ventricular (LV) ejection fraction increased from 17 +/- 5 to 27 +/- 4% (P < 0.05). Stroke volume index increased from 32 +/- 7 to 43 +/- 8 ml/beat per m2 (P < 0.05). The heart size remained stable over the long term. Following cardiomyoplasty, the number of hospitalizations due to congestive heart failure was reduced to 0.4 hospitalizations/patient per year (preoperative: 2.5, P < 0.05). Computed tomography scans showed at long term a preserved latissimus dorsi muscle structure in 84% of patients. Survival probability at 7 years is 54%. Six patients underwent heart transplant after cardiomyoplasty (mean delay: 25 months), due to the natural evolution of their underlying heart disease. There were no specific technical difficulties. CONCLUSIONS: Clinically, this procedure reverses heart failure, improves functional class and ameliorates quality of life. The latissimus dorsi muscle histological structure is maintained at long-term, when postoperative electrostimulation is performed, avoiding excessive stimulation. Cardiomyoplasty may delay or prevent the progression of heart failure and the indication of cardiac transplantation.

Coronary reoperations: indications, techniques and operative results. Retrospective study of 240 coronary reoperations.

BACKGROUND: We review twelve-year experience with coronary reoperations so as to better identify indications, techniques and results. METHODS: Between January 1986 and March 1998, 240 coronary reoperations (228 redux, 12 tridux) were performed. There were 223 male and 17 female patients, with a mean age of 63.6+/-7.9 years at the time of reoperation. Mean time interval between operations was 10+/-4.8 years. Symptomatology consisted of: stable recurrent angina (40%), unstable (57%), or congestive heart failure (3%). Pathological feature of the primary grafts was implicated in 95% of cases and atheroma sole progression over native network in 5% of cases. During reoperations 521 (2.2+/-0.8/patient) bypass [venous (40%), arterial (60%)] were performed as well as 15 associated procedures. RESULTS: Operative mortality represented 10% (n=24). Causes of death included infarct (7), left ventricular failure (12), rhythm disorders (2), mediastinitis (1) and multiorgan failure (2). Mortality risk factors were operation date (16.6% before 1992 and 7.4% after, p=0.03), age (13.1% after 60 years old, 2.7% before, p=0.01) time interval between intervention (12% after 8 years, 4% before, p=0.05) and anterograde cardioplegia only (11.8% versus 4.5% when a combined anterograde and retrograde access was used, p=0.06). Morbidity was 31% (71/240). Among the survivors 169 patients (78%) did not experience any complication. CONCLUSIONS: Thanks to a better medico-surgical management, the mortality rate of coronary reoperations is steadily decreasing.

End-to-side anastomosis using a new sutureless vascular prosthesis.

Performing a conventional vascular anastomosis during minimally invasive surgery remains a technically difficult and time-consuming task. The purpose of our study was to assess the efficacy of a new sutureless vascular prosthesis. Through a left thoracotomy, a short segment of the descending aorta was bypassed in eight sheep. Our Dacron prosthesis had a cuff at one extremity. The cuff was introduced into the artery through an arteriotomy and attached to the arterial wall with clips. Surgery was performed on the sheep again 12-15 weeks later, and the prosthesis was retrieved for macroscopic and microscopic examination. At surgery, insertion of the prosthesis was easy, fast, and safe. A 3-4 mm space between each clip was required for proper attachment. At the second surgery, all prostheses were completely patent and there were no anastomotic stenoses or aneurysms. This new sutureless vascular prosthesis was easy and safe in its placement and might prove useful for video assisted vascular aortic surgery.

[Three-dimensional modelling of thoracic aortic aneurysm. A case report]. / Modélisation tridimensionnelle des anévrismes de l'aorte thoracique. A propos d'un cas.

The anatomical forms of aneurysms are sometimes complex. Three-dimensional modelisation may be valuable in understanding the configuration and spatial orientation on one hand and also help in therapeutic decision making on the other. Two types of modelisation are reported with details of their methods and their respective values.

[Coronary reoperation: indications, methods and immediate postoperative prognosis. Retrospective study of 184 reoperations]. / Réinterventions coronaires: indications techniques et pronostic post-opératoire immédiat. Etude rétrospective sur 184 réinterventions.

The authors performed 184 coronary reoperations (172 redux, 12 tridux) between January 1986 and december 1995 in 177 patients (165 men, 12 women) with an average age at surgery of 62.9 +/- 7.6 years. The average interval between the surgical procedures was 9.5 +/- 4.5 years. The symptoms were recurrent angina, stable in 44%, unstable in 51%, and cardiac failure, 7%. Graft dysfunction was the cause in 94.5% of cases with progression of atheroma of the native coronary vessels in only 5.6% of cases. At reoperation 389 bypass procedures were performed (venous 39.5%, arterial 60.5%) (2.1 +/- 0.6 per patient) with 10 associated procedures (3 mitral valvuloplasties, 2 left ventricular aneurysmectomy, 3 aortic valve replacements, 1 replacement of the ascending aorta, 1 carotid endarteriectomy). The operative mortality was 10.9%. The causes of the 20 deaths were myocardial infarction (7), left ventricular failure (8), arrhythmias (2), mediastinitis (1) and multi-organ failure (2). The risk factors for death were: the date of surgery (19% before 1991 and 8% after: p = 0.03), age (18% after 60 years, 2% before: p = 0.015), the interval between the surgical procedures (33% after 15 years, p = 0.02), anterograde cardioplegic injection alone (15% versus 4.5% when mixed antero and retrograde perfusion was used: p = 0.02). The morbidity was 28% (52/184 patients); 132 patients (72%) had uncomplicated postoperative courses. The incidence of repeat coronary artery surgery is in constant progression. Improved medico-surgical management should continue to reduce the mortality which is still high.

[The pericardium: a heterogeneous tissue. Anatomic and morphometric considerations]. / Le péricarde: un tissu hétérogène. Considérations anatomiques et morphométriques.

BACKGROUND AND AIMS OF THE STUDY: Short-term glutaraldehyde fixed autologous pericardium is widely used in cardiac valve repair or in autologous pericardial bioprosthesis construction. The thinner the tissue, the better the fixation. The aim of this study was to determine thickness and useful surface area of pericardium in relation to harvesting site using a digital thickness counter (0.01 mm precision). Parietal pericardium fragments were obtained from the pericardial sac of six fresh cadavers (group I). In the other groups, pericardial strips (80 x 30 mm) were obtained from patients undergoing surgery: group II patients (n = 5 females) and group III (n = 10 males) were non-cardiomegalic (cardiothoracic ratio (CTR) < 0.5)), while group IV patients (n = 5) were all cardiomegalic (CTR > 0.5). Results were reported on a coloric scale according to measurement position. In group I, mean surface area was 93 +/- 18 cm2, and thickness gradually increased from 0.1 to 0.6 mm, maximally on the diaphragm, along the left heart side. In other groups, a gradual increase in thickness was identified towards the diaphragmatic zone. Significant differences in tissue thickness appear as a result of cardiomegaly, but are not related to the sex of the patients. Pericardium taken from the right anterior aspect of the pericardial sac in patients without cardiomegaly is the most appropriate tissue for valve reconstructive surgery, due to its thin nature and hence better fixation properties.

Video-assisted replacement or bypass grafting of the descending thoracic aorta with a new sutureless vascular prosthesis: an experimental study.

PURPOSE: The feasibility of the video-assisted insertion of a new sutureless vascular prosthesis was studied. METHODS: Seven sheep, weighing 25 to 35 kg, were operated on under general anesthesia. The animals were intubated with a single-lumen endotracheal tube and placed in the right lateral decubitus position. A thoracoscope was introduced in the 11th intercostal space, and a minithoracotomy (4 to 5 cm) was performed in the seventh intercostal space. After retraction of the lung, a short segment (10 cm) of the descending thoracic aorta was exposed. Our prosthesis was made of Dacron and was specifically designed to be inserted without a suture. After systemic heparinization, the aorta was cross-clamped with two vascular clamps introduced into the thoracic cavity through two 5-mm thoracic incisions. The aorta was either replaced (five cases) or bypass grafted (two cases). At the completion of the procedure, blood pressure was pharmacologically increased (5 mg intravenous bolus of epinephrine), and each anastomosis was checked for bleeding. All animals were killed, and the prosthesis was retrieved for macroscopic examination. RESULTS: The procedure was completed in each case without extension of the minithoracotomy. Insertion of the prosthesis was easy and fast, and completion of each anastomosis required 10 to 15 minutes. A 3- to 4-mm space between each clip was sufficient for proper attachment. All procedures were performed in less than 120 minutes. No bleeding was observed at the level of each anastomosis, even when a sustained high blood pressure was induced. The proper insertion of the prosthesis and the absence of any anastomotic stenosis was confirmed by means of macroscopic examination. CONCLUSION: Video-thoracoscopic replacement or bypass grafting of the descending thoracic aorta was easy with this new sutureless vascular prosthesis. Minimally invasive vascular surgery might be facilitated with such a prosthesis. However, long-term animal studies are required before human implantation can be undertaken.