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Biomedical subjects

M Lachat

Publications and source records attributed to M Lachat.

At least 37 records · Page 2Linked to original sources
PubMed1999

Explanted cryopreserved allografts: a morphological and immunohistochemical comparison between arterial allografts and allograft heart valves from infants and adults.

OBJECTIVE: Life expectancy of cryopreserved allografts implanted in infants is different from those implanted in adults. A morphological study of explanted allograft heart valves was performed to determine the mechanism of deterioration and to compare cryopreserved arterial and heart valve allografts from adult patients with those explanted from infants. METHOD: Between 1987 and 1996, 209 cryopreserved allografts were implanted: 125 valved conduits or monocusps to reconstruct the right ventricular outflow tract in congenital heart disease, 50 allograft heart valves to treat native aortic and prosthetic aortic valve endocarditis and 34 cryopreserved arterial allografts to replace mycotic aortic aneurysms or infected aortic prosthetic grafts. Two months to 8 years after implantation, 23 heart valve allografts, 11 right-sided and 12 left-sided, and four arterial allografts had to be explanted for reasons such as degeneration, recurrent infection, aneurysm formation or rupture. Besides conventional staining, immunohistochemical detection of cell populations was performed as follows: CD45RO, CD3 and CD43 for T lymphocytes, CD20 for B lymphocytes, CD68 for macrophages, protein S100 for Langerhans-cells, vimentin for fibroblasts, alpha-actin for smooth muscle cells and factor VIII for endothelial cells. RESULTS: Explanted cryopreserved allografts were all fibrotic, acellular, non-vital and without endothelial cells. The fibrous tissue was preserved. T lymphocytes, indicating rejection, were found in all right-sided allografts from the paediatric population, but only in 9% of left-sided valves explanted from adults and in one of the four of arterial allografts. Macrophages and Langerhans-cells were found only in right-sided allografts from paediatric patients. CONCLUSION: Right-sided cryopreserved allografts from a paediatric population showed ongoing cellular rejection. By contrast, there was only a weak T-cell mediated rejection to adult heart valve and arterial allografts. Therefore, similar long-term results can be expected in adult arterial and heart valve allografts, whereas longevity of right-sided heart valve allograft in the paediatric age group seems endangered by cellular rejection.

Adolescent↗
PubMed1999

Conservative treatment of the aortic root in acute type A dissection.

OBJECTIVE: In acute type A dissection long-term results of conservative aortic root surgery were compared with the outcome of primary valve and/or root replacement. METHODS: Between 1985 and 1995, 199 patients (mean age 59 years, 154 men) were operated on. The aortic root was involved in the dissection process and valve incompetence of varying degree was present without exception. Replacement of a proximal aortic segment was standard procedure in all patients. The aortic valve was preserved in 126 patients: commissural suture resuspension (12 patients), root reconstruction with GRF-glue (gelatine-resorcin-formaldehyde/glutaraldehyde-glue) (114 patients). Valve replacement was performed in 73 patients (50 composite grafts, 23 valve prostheses with separate supracoronary grafts). Preoperative risk factors (valve replacement vs. preservation): coronary artery disease (11 vs. 8%, NS), tamponade (18 vs. 17%, NS), unstable hemodynamics (22 vs. 15%, NS), renal failure (4 vs. 6%, NS), neurologic disorder (19 vs. 32%, NS). RESULTS: The overall early mortality was 23.6% (47/199 patients) and increased after commissural suture resuspension compared with GRF-glue reconstruction (P = NS). Parameters of the early postoperative period did not differ between conservative treatment and root/valve replacement: low cardiac output, 34 versus 38% (P = NS); myocardial infarction, 10 versus 11% (P = NS); hemorrhage, 25 versus 23% (P = NS); duration of intensive care (P = NS). Survival was 61% after 8 years without difference between the two principal treatment groups (P = NS) and between the two conservative subgroups (P = NS). At 2 years, GRF-glue reconstruction had an increased freedom from reoperation on the aortic root (92 vs. 70%, P = 0.0253) and event free survival (77 vs. 41%, P = 0.0224) compared with suture resuspension. Commissural suture resuspension was an independent, significant predictor for reoperation (P = 0.0221, relative risk = 4.7130). CONCLUSION: Surgery for acute type A dissection still carries a considerable early risk. Preservation of the aortic root is safe in the absence of Marfan or annuloaortic ectasia, but a certain incidence of reoperations on the aortic valve and the aortic root has to be accepted. Root reconstruction using GRF-glue is the method of choice and is superior to suture resuspension, with a significantly better reoperation-free and event-free survival.

Acute Disease↗
PubMed1999

Abdominal pulsatile tumor after endovascular abdominal aortic aneurysm repair.

A 70 years old patient was successfully treated for infrarenal aortic aneurysm by an endovascular bifurcated prosthesis. Three months later, because of dysuria, he underwent urological examination revealing an abdominal pulsatile tumor. Thereafter, the patient was sent to our emergency ward with suspected symptomatical endoleak. Radiological screening by computer tomography and magnetic resonance angiography showed good post-operative results without endoleak. Patient was treated with antispasmodic medication and is doing well today. Because endovascular repair of aortic aneurysm, in contrast to an open approach, does not eliminate the aneurysm itself, post-operative abdominal palpation can be ambiguous. Magnetic resonance angiography--without the need of nephrotoxic contrast medium--compares favourably to CT and provides excellent pictures with less artefacts for post-operative screening of endoleak. If reperfusion can be excluded, pulsation is due to the transmission of the blood-pressure wave to the thrombosed aneurysm.

Aged↗
PubMed1999

Transfemoral endografting of thoracic aortic aneurysm under local anesthesia: a simple, safe and fast track procedure.

BACKGROUND: Endovascular aneurysm grafting of the descending thoracic aorta is a minimally invasive catheter technique, which is performed under general anesthesia. We describe a technique allowing to perform transfemoral endovascular repair of thoracic aortic repair under local anesthesia. PATIENTS AND METHODS: In 9 consecutive patients local anesthesia was performed in order to gain an opened femoral artery access for the delivery system, and a percutaneous access to the left brachial artery. A pigtail catheter was then placed through the left brachial artery for the location of the origin of the left subclavian artery and/or the aneurysm and self-expanding endoprosthesis was released under fluoroscopic guidance. For the deployment of the endograft a short period of controlled hypotension with nitroglycerin bolus application was produced. RESULTS: All the aneurysms could be successfully sealed with the intended endovascular technique. There was no vascular access complication or pulmonary or ischemic (cardiac, cerebral or peripheral) complication. In the follow-up period of 6 +/- 3 months one patient needed a redo endovascular procedure because of the development of a severe and symptomatic distal endoleak 6 weeks postoperative. This procedure was again performed under local anesthesia. CONCLUSIONS: From a technical point of view, transfemoral endovascular repair of thoracic aneurysm can be performed under local anesthesia. This is a very simple and fast track procedure which combines a minimally invasive catheter technique and a less invasive anesthetic management.

Adult↗
PubMed1999

Flow measurements through aortocoronary and intraluminal coronary shunts.

AIMS: Temporary insertion of shunts during coronary artery bypass grafting (CABG) on the beating heart may provide the minimal flow required for adequate myocardial protection (40 to 60 ml/min). We investigated the flow as a function of the pressure head over three aortocoronary shunts and one intraluminal coronary shunt. METHODS: The aortocoronary shunts (VS-01590 with bulb size 2, 3 and 4 mm) and the intraluminal shunt (IVS-4030, bulb size 4 mm) were perfused with 47% glycerin solution at 37 degrees C. The preload was raised in 5 mmHg steps from 35 to 80 mmHg. The afterload was set at 12 mmHg. A regression analysis of the flow on the pressure head was performed. RESULTS: For maximal preload the flow through the aortocoronary shunts was 15.9 +/- 1.3, 46.2 +/- 2.2 and 75.4 +/- 3.3 ml/min, for the intraluminal shunt it was 76.1 +/- 3.4 ml/min. To provide a flow of 40 ml/min a preload of 70, 50 and 45 mmHg was necessary for the 3 mm and 4 mm aortocoronary shunt and the intraluminal shunt respectively. For the aortocoronary and the intraluminal shunts the beta-coefficients were 0.27, 0.66, 1.13 and 1.02 ml/(min*mmHg) respectively with all p < 0.0001. CONCLUSIONS: For adequate pressure head the 3 mm and 4 mm aortocoronary shunt and the intraluminal shunt provide myocardial protection. In case of severe proximal coronary stenosis the intraluminal shunt will not guarantee myocardial protection and main benefit reduces to working in a bloodless field. The insertion of shunts is a cheap and simple method to optimize CABG on the beating heart.

Arteriovenous Shunt, Surgical↗
PubMed1999

[Emergency surgery for abdominal aortic aneurysm--could an endovascular methods be considered?].

AIMS: The endovascular repair of abdominal aortic aneurysms (AAA) is a minimally invasive method which can be performed without laparotomy, thoracotomy or cross-clamping. Little is known about the endovascular feasibility in patients with contained ruptures. METHODS: Retrospective study on 31 patients (mean age 70 +/- 6 years, 27 men (87.1%) and 4 (12.9%) women), who were treated for a ruptured aortic aneurysm between January 1996 and July 1998. RESULTS: 17/31 (55%) patients were hemodynamically stable. 14 patients were in severe shock and two died preoperatively. The operative mortality (two just after entering the abdomen) was 17% (5/29 patients) due to irreversible shock. A graft repair was performed in 27 patients. Preoperative CT scan was available in 12/31 (39%) patients. An infrarenal neck was present in all patients (length: 19 +/- 9 mm, internal diameter: 23 +/- 5 mm). The internal diameter of the external iliac artery was 10 +/- 2 mm. Six patients has an additional aneurysm of the common iliac artery, none of them bilaterally. In one patient infrarenal kinking of more than 90 degrees was detected. CONCLUSIONS: In regard to the morphology, endovascular treatment would have been feasible in the majority of the patients where CT was already performed. Moreover, hemodynamic situation would have allowed to assess feasibility with a CT and perform endovascular treatment in most of patients with symptomatic or ruptured AAA. In conclusion, hemodynamically stable patients with symptomatic or leaking AAA should be investigated for endovascular repair.

Age Factors↗
PubMed1999

Composite graft replacement of the aortic root: long-term results, incidence of reoperations.

BACKGROUND: Long-term results after composite graft replacement of the aortic root may depend on the insertion technique. METHODS: 181 consecutive patients (mean age 53 years; 153 men) operated on between 1983 and 1993 were studied. Indications for surgery were annuloaortic ectasia (n=98), acute aortic dissection (n = 46), other indications (n = 12), and various indications after previous aortic valve replacement (n = 25). Mean follow-up was 28 months. The open-button technique was performed in 74 patients (41 %) and the Bentall inclusion technique in 107 patients (59%), with a Cabrol shunt to the right atrium in 16 patients. RESULTS: Overall survival was 75% after 7 years, significantly decreased in acute aortic dissection (p = 0.0019) and without difference between the two surgical techniques (p = 0.3166). Reoperation-free survival was 69% at 7 years and significantly decreased after acute dissection (p = 0.0421 ). Pseudoaneurysm formation only occurred in 3 patients operated with the Bentall technique not including a Cabrol shunt. CONCLUSIONS: Long-term results are satisfactory. In acute aortic dissection survival is decreased and late reoperations more frequent. The open technique is safe in non-dissection and in acute dissection and avoids pseudoaneurysm formation. The Bentall technique combined with Cabrol shunt is indicated if there is a high risk of hemorrhage. Long-term monitoring of the aorta is mandatory in patients with acute dissection and/or Marfan disease.

Acute Disease↗
PubMed1999

Optimized performance of the Abiomed BVS 5000: adjustment of the pump height based on Doppler control of the flow pattern.

The Abiomed BVS 5000 is an automatic volume-driven paracorporeal pulsatile assist device providing left, right or biventricular support. The paracorporeal position allows optical adjustment of filling volumes of the device, which determines the output of the system. A procedure to adjust for maximal stable flow has not yet been established. In vitro measurements have been performed to assess the flow and pressure characteristics of the Abiomed BVS 5000 by raising the preload in 5 mmHg steps before running the system. Doppler probes were placed at the inflow and outflow lines of the pump. After setting the afterload at 80 mmHg the assist device was started. Two measurements were performed to find optimal flow (based on Doppler control and optical adjustment). (1) By Doppler control a stable flow pattern was found at a preload of 25 mmHg with a mean atrial pressure of 5 mmHg and a mean flow of 5.3 +/- 0.7 l/min (mean +/- standard deviation) at the inflow and outflow sites (the console flow was 4.8 +/- 0.4 l/min with a frequency of 61.8 +/- 2.0 l/min). (2) Optical adjustment of the pump height gave rise to a preload of 35 mmHg where we recorded a maximal atrial pressure of 107 +/- 5.8 mmHg, a maximal retrograde flow of -4.3 +/- 1.2 l/min at the inflow and -1.2 +/- 0.4 l/min at the outflow site. The mean flow at the inflow and outflow sites was 5.1 +/- 0.5 l/min (the console flow was 4.6 +/- 0.3 l/min with a frequency of 59.6 +/- 2.6 Hz). At an initial afterload of 60 and 40 mmHg the system showed the same qualitative behaviour, but the results were less accurate. Optical adjustment of the pump height may result in an atrioventricular valve insufficiency with undetected retrograde flow and high atrial pressures. We conclude that a Doppler flow probe must be placed at the inflow site to guarantee maximal stable flow.

Equipment Design↗
PubMed1999

Hemodynamic properties of the hemopump HP14.

BACKGROUND: The Hemopump HP14 is a catheter-mounted, transvalvular, left ventricular assist device intended for femoral percutaneous insertion. The pump was developed for patients with postoperative or postinterventional low cardiac output and for CABG surgery on the beating heart. Little is known about the effect of afterload and hematocrit on the pump performance. METHODS: The influence of hematocrit and afterload on the pump flow was tested using an in vitro model filled with heparinized bovine blood. Regression analysis of the pump flow with respect to three hematocrit values (20%, 30%, 40%) and ten afterload levels (30 mmHg-120 mmHg in 10 mmHg increments) was performed for all pump speed levels (n = 7). RESULTS: At all pump speed levels reduction of afterload and hematocrit were significant predictors for increasing pump flow (p<0.001). For hematocrit values between 40% and 20% and highest pump speed, mean pump flow at lowest afterload ranged between 2.34 and 2.53 L/min; and at highest afterload between 1.31 and 1.53 L/min. For speed level 1, afterload of 120 mmHg and hematocrit of 40% there was a maximal retrograde flow of 230+/-35 ml/min. CONCLUSIONS: Pump performance is significantly improved by both afterload and hematocrit reduction. In the weaning phase and during the removal of the device, the pump should run at a speed level of at least three to prevent retrograde flow in the pump. Estimates for pump flow in vivo can be extrapolated from our diagrams. Our results show that the Hemopump HP14 is a valuable alternative to intra-aortic balloon counterpulsation.

Animals↗
PubMed1998

Tissue engineering: a new approach in cardiovascular surgery: Seeding of human fibroblasts followed by human endothelial cells on resorbable mesh.

OBJECTIVE: In tissue engineering the material properties of synthetic compounds are chosen to enable delivery of dissociated cells onto a scaffold in a manner that will result in in vitro formation of a new functional tissue. The seeding of human fibroblasts followed by human endothelial cells on resorbable mesh is a precondition of a successful creation of human tissues such as vessels or cardiac valves. METHODS: Polymeric scaffolds (n = 18) composed of polyglycolic acid (PGA) with a fiber diameter of 12-15 microm and a polymer density of 70 mg/ml were used as square sheets of 1 x 1 x 0.3 cm. Fibroblasts (passage 7) harvested from human foreskin were seeded (3.4 x 10(6)) and cultured over a 3 week period on a PGA-mesh, followed by seeding of endothelial cells (passage 5, 2.8 x 10(6)) harvested from human ascending aorta. Thereafter the new tissue was stained for HE, van Gieson, Trichrom Masson, Factor VIII and CD 34 and proved by scanning electron microscopy. RESULTS: Microscopic examination of the seeded mesh demonstrated that the human fibroblasts were attached to the polymeric fibers and had begun to spread out and divide. The scanning electron microscopic examination demonstrated a homogeneous scaffold resembling a solid sheet of tissue. The seeded endothelial cells formed a monolayer on the fibroblasts and no endothelial cell invasion or new formation of capillaris could be detected. CONCLUSIONS: These results are a first step to demonstrate that seeding of human fibroblasts and endothelial cells on PGA-mesh might be a feasible model to construct human tissues such as vessels or cardiac valves.

Aorta↗
PubMed1998

Preoperative predictors of recurrent atrial fibrillation late after successful mitral valve reconstruction.

OBJECTIVE: Late outcome after mitral valve repair was examined to define preoperative predictors of recurrent atrial fibrillation late after successful mitral valve reconstruction. METHODS: One hundred and eighty-nine patients, 112 with preoperative sinus rhythm and 72 with preoperative chronic or intermittent atrial fibrillation, were followed for 12.2 +/- 10 years after valve repair. Clinic, hemodynamic end echocardiographic data were entered into Cox-regression and Kaplan-Meyer analysis to assess predictors for recurrent atrial fibrillation late after successful mitral valve repair. RESULTS: Univariate and multivariate predictors for recurrent atrial fibrillation late after successful mitral valve reconstruction were preoperative atrial fibrillation (P = 0.0001), preoperative antiarrhythmic drug treatment (P = 0.005), heart rate (P = 0.01), left ventricular ejection fraction (P = 0.01) and increased left ventricular posterior wall thickness (P = 0.05). Patients > 57.5 years with a mean pulmonary artery pressure > or =23 mm Hg and a history of preoperative antiarrhythmic drug treatment had an odds ratio of 53.33 (95% confidence limits 6.12-464.54) for atrial fibrillation late after successful mitral valve repair. CONCLUSION: Older patients with a history of atrial fibrillation, antiarrhythmic treatment or an elevated pulmonary artery pressure may present atrial fibrillation late after successful mitral valve repair. They could be considered for combined mitral valve reconstruction and surgery for atrial fibrillation even though sinus rhythm is present preoperatively.

Adult↗
PubMed1998

[How to do: initial experiences with a new device in minimally invasive heart surgery].

A special surgical technique is required for minimal-invasive cardiac surgery. The view for the coronary artery anastomosis under beating heart conditions is important and coronary artery blood might prevent a clear view of the opened coronary artery vessel. A new system called VisoFlo promises to improve visualisation at the surgical site. VisoFlo delivers a column of air to help provide a clear view of anastomosis site and in addition has a controllable mist to help prevent desiccation of the graft and surrounding tissue. This system was tested on 45 patients with coronary-artery-bypass graft surgery under beating heart conditions and at 65 patients with standard coronary-artery-bypass graft surgery. Our conclusions are, that the VisoFlo system is easy to use, guarantees a clear view of the anastomosis site and the surgical work will not be impaired.

Anastomosis, Surgical↗
PubMed1998

Tissue engineering: a new approach in cardiovascular surgery--seeding of human fibroblasts on resorbable mesh.

INTRODUCTION: In tissue engineering the material properties of synthetic compounds are manipulated to enable delivery of dissociated cells onto a scaffold in a manner that will result in in vitro formation of new functional tissue. The seeding of human fibroblasts on resorbable mesh is a precondition of a successful creation of human tissue such as autologous cardiac valves. MATERIAL AND METHODS: Polymeric scaffolds (n = 12) composed of polyglycolic acid (PGA) with a fiber diameter of 12-15 mm and a polymer density of 70 mg/ml were used as square sheets of 0.3 x 1 x 1 cm. Fibroblasts (passage 5), harvested from human foreskin, were seeded (3.4 x 10(6)) and cultured over a 3 week period on a PGA mesh. RESULTS: Microscopic examination of the seeded mesh demonstrated that the human fibroblasts were attached to the polymeric fibers and had begun to spread out and to divide. Electron microscopy showed a continuous distribution and formation of the cells throughout the "polymeric architecture". Spotlike hydrolysis of PGA fibers was observed. After 3 weeks the seeded scaffolds resembled a solid sheet of tissue. CONCLUSION: These preliminary results, successful seeding of human fibroblasts on a PGA mesh, represent a first basic step on the way to construct human tissue such as autologous cardiac valves and demonstrate that tissue engineering might be a promising new device in therapy of cardiovascular disease.

Cells, Cultured↗
PubMed1998

Wash out technique for proximal anastomosis in atherosclerotic ascending aorta.

BACKGROUND: Especially among elderly patients embolisms originating from atheromatous plaques in the ascending aorta are responsible for cardiac and cerebral events during coronary bypass surgery. Unfortunately smooth atheromatous degeneration of the aorta often can not be detected even by transoesophageal echocardiography. METHODS: In four patients with unexpected atheromatous material of the punched ascending aorta the so called "wash out technique" was performed. A side-to-end anastomosis between a segment of vein and the partially clamped ascending aorta was performed. For several minutes the ascending aorta was left to bleed through the venous stump. Without further manipulation of the ascending aorta the coronary bypass graft was completed by an end-to-end anastomosis between the venous stump and the venous graft. Oral anticoagulation in combination with a low dose platelet antiaggregation drug was given for at least one year. RESULTS: All patients had an uncomplicated postoperative course, especially with regard to neurological damage or ECG changes. CONCLUSIONS: In patients with unexpected atheromatous pathology of the ascending aorta the "wash out technique" of coronary artery bypass grafting minimises direct embolisation into the cardiac area perfused by the new bypass grafts.

Aorta, Thoracic↗
PubMed1997

Minimally invasive coronary artery bypass techniques as adjunct to extracardiac procedures.

BACKGROUND: Surgical management of coronary artery disease has improved dramatically over the last decades in terms of short- and long-term results. Nevertheless, elderly patients (more than 75 years); patients with reduced ejection fraction (less than 0.25), heavily calcified aorta, or coexisting noncardiac diseases; and patients requiring cardiac reoperation have an increased perioperative risk when operated on with cardiopulmonary bypass. Successful minimally invasive coronary artery bypass grafting without cardiopulmonary bypass has been reported in selected cases. METHODS: In 8 of 40 high-risk patients undergoing operation on a beating heart, minimally invasive coronary bypass grafting was combined with vascular (carotid endarterectomy, n = 3; aortic replacement, n = 2) and abdominal procedures (a second look after combined pancreas and kidney transplantation) or defibrillator implantations (n = 2). RESULTS: Postoperatively, there was no mortality, no morbidity, and no blood transfusion. Patients are free of symptoms at an average follow-up time of 5.5 +/- 5 months. CONCLUSIONS: Our results indicate that minimally invasive coronary artery bypass grafting technique can be particularly useful if noncardiac procedures have to be performed in high-risk patients with significant coronary artery disease.

Abdomen↗