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Biomedical subjects

P Lajos

Publications and source records attributed to P Lajos.

14 recordsLinked to original sources
PubMed2000

[Utilization of aortomyoplasty as a biological pumping system].

Aortomyoplasty is a surgical technique of constructing a neo-ventricle on the ascending or descending aorta with the latissimus dorsi muscle. This is electrically stimulated to contract during diastole, thereby creating a system of chronic, haemo-compatible aortic pumping. Long-term experimental studies have shown increases in cardiac output (from 3.6 to 5.5 l/min), decreases in peripheral resistances (from 1574 to 1134 dyne.sec.cm-5) and increases in indices of subendocardial viability (DPTI/TTI: 1.1 to 1.4). These experimental studies have been confirmed by the initial clinical results. To date, world experience includes thirty-six patients. With cardiomyoplasty, aortomyoplasty is a new arm in the therapeutic arsenal against severe cardiac failure by providing a new system of chronic circulatory assistance which is implantable and biocompatible.

Aorta, Thoracic↗
PubMed1999

Single breath exhaled nitric oxide in lung transplant patients: a preliminary clinical study.

Exhaled nitric oxide is considered as a marker of airway inflammation. We report here our preliminary experience with single-breath exhaled nitric oxide measured in lung transplant patients with and without bronchiolitis obliterans syndrome and in cardiac transplant patients. Peak and end-expiratory nitric oxide concentrations did not differ between groups, but single-breath exhaled nitric oxide recordings were strikingly different in patients suffering from bronchiolitis obliterans syndrome, with a slower decrease from peak to end-expiratory nitric oxide concentration. Further studies are required in order to determine whether theses abnormalities reflect the inflammatory process of bronchiolitis obliterans syndrome.

Adult↗
PubMed1999

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.

Animals↗
PubMed1998

Less invasive techniques for mitral valve surgery.

OBJECTIVE: Minimally invasive surgical techniques aim at reducing the consequences of currently used large incisions, such as bleeding, pain, and risk of infection. Although this new approach developed rapidly in coronary surgery, it remains questionable in mitral valve surgery. This article reports the longest experience with minimally invasive mitral valve surgery, with particular attention to approach and techniques. METHODS: From February 1996, the date of the first case of minimally invasive mitral valve reconstruction, to April 1997, 22 patients with a mean age of 54 +/- 2.7 years were subjected to mitral valve surgery performed with less invasive techniques. Exposure of the mitral valve was achieved through a minithoracotomy (n = 12) or a ministernotomy (n = 10). Video assistance was used in all cases. Peripheral arterial cannulation (n = 21) and venous drainage (n = 22) were used in most cases. RESULTS: In this series, valve surgery consisted in 19 repairs, two replacements, and one closure of a periprosthetic leak. In two cases it was necessary to convert to a larger incision. The average duration of cardiopulmonary bypass was 157 +/- 8.2 minutes, ventilatory assistance 16 +/- 4.6 hours, and intensive care unit stay 2.1 +/- 0.4 days. Two patients required reoperation for bleeding and another for early recurrence of mitral valve regurgitation. There were no deaths and all patients were discharged with normal valve function. At most recent follow-up, all patients were in functional class I, with resumption of normal activity. CONCLUSION: Mitral valve surgery can be performed safely by means of less invasive techniques, but with increased technical difficulty. A low asymmetric median sternotomy seems preferable to an anterior thoracotomy.

Cardiopulmonary Bypass↗
PubMed1998

Bi-directional cavopulmonary shunt associated with ventriculo and valvuloplasty in Ebstein's anomaly: benefits in high risk patients.

OBJECTIVE: The prognosis for surgical repair of Ebstein's anomaly depends on the tricuspid valve repair and on the right ventricular function. In order to decrease the preload of the compromised right ventricle, a bi-directional cavopulmonary shunt was added to the intracardiac repair. METHODS: Among 113 patients operated on for Ebstein' s anomaly at our institution from 1980-1997, a cohort of 60 patients was selected for high risk for postoperative complications. Patients presented with one or more several criteria: massive tricuspid valve dysfunction, extended atrialized right ventricle, poor right ventricular contractility, or long standing atrial fibrillation. After prior informed consent, this cohort was divided into two groups. Both groups had similar preoperative clinical patterns: Group I (45 patients), surgical technique included longitudinal right ventricular plication and tricuspid valve valvuloplasty; Group II (15 patients), where the surgical technique was similar to Group I except a bi-directional cavopulmonary shunt was added at the end of the procedure. RESULTS: Operative mortality was 24% (11/45) in Group I and 0% (0/15) in Group II (P < 0.05). The survival at 5 years was 66.1 +/- 14% in Group I and 80 +/- 16% in Group II (not significant). Reoperation rate was 11% (5/45) in Group I and 0% (0/15) in Group II. No deleterious effects of the bi-directional cavopulmonary shunts were observed clinically. Residual tricuspid valve insufficiency rate was 26% in both groups. However, patients with the bi-directional cavopulmonary shunt had a better tolerance and have not needed reoperations to date. CONCLUSIONS: In high risk patients with Ebstein's anomaly, an associated bi-directional cavopulmonary shunt seems to offer several distinct advantages including decreased operative mortality and better tolerance of the residual tricuspid valve dysfunction.

Adolescent↗
PubMed1998

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.

Biomechanical Phenomena↗
PubMed1997

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.

Actuarial Analysis↗
PubMed1989

Prevention of reperfusion injury in ischemic-reperfused hearts by oxypurinol and allopurinol.

We investigated the effects of the xanthine oxidase inhibitor allopurinol and its metabolite oxypurinol on isolated rabbit hearts. To assess the potential role of these drugs in preventing reperfusion injury, hearts were perfused using Langendorff techniques, held globally ischemic for 3 h at 15 degrees C, and then reperfused. During perfusion, hearts received Krebs-Henseleit solution maintained at 37 degrees C. Aortic perfusion pressure was held constant at 80 cm H2O. Prior to ischemia, hearts were arrested with a constant volume of KCl cardioplegia. Using a left ventricular (LV) balloon, developed pressures were measured prior to and following global ischemia. In addition, coronary circulation (CC) was measured before and after ischemia. All hearts were paced at 260 beats/min. We studied four groups: group 1 received 1 mM allopurinol, group 2 received 1 mM oxypurinol, group 3 received 90 IU/ml superoxide dismutase (SOD) plus 8085 IU/ml catalase (CAT), and group 4 received no treatment and served as a control. Each group consisted of 8 animals. Hearts receiving drug treatment did so during the first 5 min of reperfusion. Displaying all data as a function of LV volume, postischemic values were compared to preischemic values. Multivariate analysis and Tukey tests were used to detect significant differences between groups. When compared to the control group, all drug-treated groups significantly recovered end-diastolic function. Peak systolic pressure decreased significantly in the SOD/CAT group as compared to all other groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Allopurinol↗
PubMedDate not supplied

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.

Anastomosis, Surgical↗
PubMedDate not supplied

Allopurinol in prevention of reperfusion injury of hypoxically stored rat hearts.

We have studied the effect of the xanthine-oxidase inhibitor allopurinol on the performance of hypoxically stored rat hearts to evaluate the drugs' potential value in heart transplantation. Hearts were stored for 2 hours at 15 degrees C after potassium chloride cardioplegia. Hemodynamics were measured before hypoxia and after reperfusion. Hearts were treated with allopurinol in the cardioplegia, at the time of reperfusion, or with superoxide dismutase (SOD) and catalase (CAT) and compared with control hearts that received no treatment. Hemodynamic performance after hypoxia was significantly improved in the SOD/CAT group compared with the control group. Allopurinol-treated hearts were also significantly improved, especially when the drug was given in the reperfusion phase. Our results demonstrate the importance of free radicals during reperfusion of hypoxically stored hearts. Allopurinol and SOD/CAT may be of value in reducing such damage after heart transplantation.

Allopurinol↗