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Biomedical subjects

J F Obadia

Publications and source records attributed to J F Obadia.

At least 37 records · Page 2Linked to original sources
PubMed1997

Outcome of atrial fibrillation after mitral valve repair.

OBJECTIVE: The aim of the study was to evaluate the prognostic factors for return to sinus rhythm after mitral valve repair. METHOD: One hundred ninety-one patients underwent surgery for mitral valve repair, including 142 procedures for valve repair only (74%). The patients with preoperative atrial fibrillation (50.5%) were older, clinically more symptomatic, and had a greater degree of left atrial dilation than the patients who had sinus rhythm. RESULTS: Preoperative cardiac rhythm, the duration of preoperative atrial fibrillation, and a lesser degree of left atrial hypertrophy are significant prognostic factors independent of the maintenance of sinus rhythm. The probability of return to stable sinus rhythm was 93.7% when sinus rhythm was already present before the operation and 80% when atrial fibrillation was intermittent or of less than 1 year's duration; probability declined abruptly for durations over 1 year. No significant difference in patient survival was noted between those who had sinus rhythm (99% +/- 0.9% at 1 year and 86% +/- 6.6% at 5 years) and those who had atrial fibrillation in the preoperative period (95% +/- 3.1% at 1 year and 86% +/- 8.4% at 5 years). In contrast, the postoperative return to sinus rhythm was associated with 99% +/- 0.9% and 94% +/- 4.8% survivals at 1 and 4 years versus 97% +/- 1.5% and 77% +/- 13% in the event of postoperative atrial fibrillation. CONCLUSION: The aim of restoring postoperative sinus rhythm after mitral valve repair should lead to surgery being conducted on patients who have sinus rhythm or recent-onset atrial fibrillation. Surgery for atrial fibrillation may be of value in patients with a long history of atrial fibrillation, providing that it does not induce prohibitive excess mortality.

Adult↗
PubMed1997

Mechanical cardiac valve thrombosis in patients in critical hemodynamic compromise.

BACKGROUND: Valve obstruction is a life threatening complication of mechanical valve prosthesis. METHODS: From 1985 to 1993, 29 consecutive patients were hospitalized in our intensive care unit for mechanical prosthetic valve thrombosis (PVT). There were 12 men and 17 women aged 25-75 years (57 +/- 12). Prosthetic valve location was mitral in 14 patients, aortic in 6, aortic and mitral in 9. PVT occurred from 15 days to 174 months (67 +/- 52 months) after surgery. Delay from first symptoms to hospitalization ranged from 1 to 45 days (11 +/- 11). RESULTS: First clinical symptoms were progressive left heart failure in 17 patients, stroke in 6, and chest pain in 6. Furthermore, acute myocardial infarction was later documented in 3. Left heart failure NYHA III-IV was present in 26 patients (90%) on admission and 10 of those were in cardiogenic shock. Anticoagulation regimen was inadequate in 13 cases (45%). It has been recently stopped in 8 patients and incorrectly conducted in 5. Total hospital mortality was 41.3% (12). It was independent of type and position of the valve prosthesis. Diagnosis of PVT was only made at autopsy in 3 patients who died of recurrent myocardial infarction (2) or cardiogenic shock (1). Five further patients died before any surgery could be attempted (cardiac arrest: 2, cardiogenic shock: 3). Valve replacement could be done in 21 cases, 7 of whom were in cardiogenic shock and 9 had severe pulmonary edema. Four patients died after surgery, the operative mortality was 19%. CONCLUSION: PVT remains a serious complication of mechanical heart valve prostheses. Overall mortality rate is high, related to difficulty to diagnosis, delay to hospitalization and severe clinical condition at admission. In our study, operative risk remained acceptable even when the clinical presentation was severe.

Adult↗
PubMed1997

Design of an isolated pig heart preparation for positron emission tomography and magnetic resonance imaging.

RATIONALE AND OBJECTIVES: Validation of new positron emission tomography (PET) tracers or magnetic (MR) imaging contrast agents is based on isolated rodent heart preparations. The use of larger animals could provide a more direct validation using the devices used for humans. METHODS: An isolated pig heart preparation has been developed and adapted to the technical constraints of whole body PET and MR imaging. This preparation could be used either in the Langendorff or working mode after selective cannulation of both coronary arteries. RESULTS: The authors showed that quantification of regional kinetics of PET tracers was possible using this preparation by measuring fluorine-18-labeled deoxyglycose (18FDG) kinetics in remote and ischemic territories. Experiments using MR imaging contrast agents, for myocardial perfusion, demonstrated the ability of this preparation to accurately validate these contrast agents over a wide range of flow rates. CONCLUSIONS: An isolated pig heart preparation could be developed to fulfill the constraints of PET and MR imaging, and proved useful for the study of the distribution of different tracers or contrast media developed for functional cardiac imaging in humans.

Animals↗
PubMed1997

Beneficial actions of preconditioning and stretch on postischemic contractile function of isolated working rat heart: effects of staurosporine.

Preconditioning is commonly induced by a brief ischemic insult; myocardial stretch can trigger this protection by an unknown mechanism. Myocardial stretch preconditions the in vivo canine heart; however, the existence of a stretch-induced protection in the rat heart remains unknown. The purpose of this study was to test this myocardial protection induced, in isolated working rat heart, by global ischemia and stretch initiated by a transient increase in the left ventricle (LV). Isolated rat hearts underwent 30 min of global ischemia followed by 30 min of reperfusion. Before this, hearts received a 15-min period of either no intervention (control; C), 5 min of global ischemia + 10 min of reperfusion (preconditioning; PC) or 5 min of stretch + 10 min with no intervention (stretch; S). Stretch was induced by a transient increase in LV preload from 5 to 20 cm H2O. LV work started under a afterload of 80 cm H2O. Control, PC, and S hearts received either no drug (untreated) or staurosporine (50 nM), a protein kinase C inhibitor, before the "preconditioning" period. Creatine kinase (CK) release, ventricular fibrillation during reperfusion, and postischemic recovery of contractile function (aortic flow) were the end points of the study. In the S group, the abrupt increase in preload resulted in a significant increase of aortic flow (42 +/- 2 to 47 +/- 2 ml/min; p < 0.05). During the 30-min reperfusion period, control hearts displayed a poor recovery of contractile functions (8 +/- 3 ml/min, 30 min after reflow, versus 40 +/- 2 ml/min at baseline; p < 0.05). Both untreated PC and S groups exhibited a significant reduction in CK release, incidence of ventricular fibrillation (55% of control hearts developed persistent VF vs. 6% in both the PC and S groups), and postischemic dysfunction during reperfusion (p < 0.05 vs. control). Staurosporine prevented these beneficial effects in PC and S groups. Our study suggests that myocardial protection can be induced by stretch in the isolated working rat heart, likely through activation of protein kinase C. In conclusion, our results show that ischemic preconditioning and stretch had comparable favorable effect on functional recovery after a sustained ischemic insult in the isolated rat heart.

Animals↗
PubMed1997

Long conservation organs in heart transplantation: postoperative results and long-term follow-up in fourteen patients.

Between 1988 and 1995, 14 heart transplantations were performed after a long preservation period (10 to 13 hours). The transplantation procedure (Shumway) was standard, and our results were achieved through the implementation of a very strict reperfusion technique that included low pressure and low cardiopulmonary bypass output for the first 10 minutes. Three patients died during the postoperative period, and the survival rate was 75% at 1 year and 71% at 5 years. The results obtained with hearts stored for such long periods are comparable to the results obtained with hearts stored for less than 4 hours.

Adolescent↗
PubMed1997

Defibrillation threshold and electrode configurations: an experimental study testing three configurations in twelve pigs.

OBJECTIVE: The choice between epicardial or subcutaneous patches remains unclear and depends essentially on the team's habits. This study tested how much an additional patch can decrease defibrillation threshold (DFT), and compared a Subcutaneous Array and an epicardial patch. Today most implantable automatic defibrillators have a transvenous endocardial configuration alone but when the DFT remains high an additional patch is necessary. EXPERIMENTAL DESIGN: Three different configurations were tested with biphasic shocks in 12 pigs: Endovenous lead (Endo), Endovenous lead + subcutaneous patch (Endo + SQ) and Endovenous lead + epicardial patch (Endo + Epi). For each animal DFTs were determined in a balanced random order for the 3 configurations. Ventricular fibrillation was induced by pacing (30 Hz, 8 V, for 5 seconds). DFT was accurately measured with the up/down procedure until 3 reversal of defibrillation success or failure occurred. DFTs (mean +/- SD) were extracted and compared using paired t test and analysis of variance. RESULTS: DFTs were 14.6 +/- 11.0 J for Endo and significantly decreased (p < 0.01) when an additional SQ (9.4 +/- 7.2 J) or epicardial patch (8.9 +/- 6.5 J) was added to endovenous lead, without significant difference between Endo + SC and Endo + Epi configurations. CONCLUSIONS: Regarding this important decrease of DFT (respectively -35% for Endo + SC and -39% for Endo + Epi), additional patches should be more often recommended in patients with low safety margin of DFT. In those cases subcutaneous patches should be preferred instead of epicardial patches. Moreover, an additional reason to recommend this attitude could be the possible generator batteries saving.

Animals↗
PubMed1997

[Thoracic aortic aneurysm in Marfan syndrome].

Thoracic aortic aneurysms are the main cardiovascular complication of Marfan's syndrome. Elastic tissue dystrophy of the ascending aorta is responsible for appearances of cystic medial necrosis in the major forms. Dilatation of the ascending aorta is progressive with time. The risk of dissection and rupture, an acute complication of Marfan's syndrome, is very high when the aortic dilatation reaches 60 mm, although dissection may be observed with dilatation of 50 mm. Aortic regurgitation is found in half the cases. Echocardiography, CT scan and MRI provide accurate assessment of the anatomy of the lesions and help in following up the dilatation. Betablocker therapy slows down the progression of the dilatation. Bentall's procedure was first described in 1968 with its technical variants for reimplantation of the coronary arteries: Cabrol's procedure, technique of periostal lean-to, the button technique, are major advances in the surgical treatment of ascending aortic aneurysms. The life expectancy is reported to be about 90% at 5 years and 75 to 80% at 10 years. Reoperation is sometimes necessary because of pseudo-aneurysms occurring as a late complication at the operation site or because of other aneurysms developing. Progress in the field of genetics is a hope for the future.

Adrenergic beta-Antagonists↗
PubMed1996

Thoracoscopic approach to implantable cardioverter defibrillator patch electrode implantation.

Even if transvenous lead system for automatic implantable cardioverter defibrillators (ICDs) has been one of the main surgical advances in the recent past, its major limitation is the high defibrillation thresholds in some cases. Thus, an additional patch may be required and implanted either in a subcutaneous position or in an epicardial position. We describe another possibility: the implantation of extrapericardial patch under video-thoracoscopic control. This new technique allows a deep implantation of the whole material without thoracotomy. Seven patients were included in our preliminary experience. During defibrillation threshold evaluation, two patients required 34 J with the single transvenous lead system, and five patients were not defibrillated with the single lead system; therefore, they required a 300-J external rescue shock. We decided to implant an additional patch in those seven patients with high defibrillation thresholds. This patch was inserted into the pleural cavity through a left subcostal incision. Under video thoracoscopy, it was positioned and stitched onto the pericardium. The defibrillation generator was then implanted through the left subcostal incision in a subdiaphragmatic space. As a result, preoperative defibrillation thresholds were significantly reduced (14.29 +/- 3.45 J, mean +/- SD) and remained stable during follow-up controls (eighth day and second month). Long-term follow-up (14 +/- 4.5 months) was uneventful, with an excellent tolerance for the patients. In conclusion, extrapericardial implantation of defibrillation patches under video thoracoscopy is an easy technique that allows low defibrillation thresholds.

Adult↗
PubMed1996

Crystalloid versus cold blood cardioplegia in patients operated on for myocardial revascularisation.

Post-ischemic reperfusion phenomenon has been studied in two methods of myocardial protection: a crystalloid cardioplegia (St Thomas no.2) and a cold blood cardioplegia (Buckberg) during cardiopulmonary bypass for myocardial revascularisation in patients. Myocardial protection has been assessed from the evolution of hemodynamic parameters, reperfusion arrhythmias and biochemical analysis of the coronary flow after cross-clamp removal: creatinine phosphokinase (CPK_MB) and nucleotide adenine metabolites (adenosine, inosine, hypoxanthine, xanthine and uric acid). The study was performed in two groups of 14 patients. Hemodynamic conditions were similar in both groups during reperfusion in order to avoid different coronary flow. In those conditions, myocardial protection by cold blood cardioplegia reduced reperfusion arrhythmias, and resulted in a loss of CPK-MB release. Furthermore, the reduction of metabolites release, purine bases and oxypurine bases into coronary sinus after cold blood cardioplegia suggest a better protection of myocardial high energy phosphates in this group than after crystalloid cardioplegia. Our results also show that hypoxanthine is probably the final product of ATP degradation in human myocardial tissue.

Adenosine Triphosphate↗
PubMed1996

[Aneurysms of the left ventricle without atheromatous coronary artery disease. Apropos of 2 cases].

Left ventricular aneurysms are usually secondary to myocardial infarction with atheromatous coronary artery disease. The authors report two rare cases of non-atheromatous left ventricular apical aneurysms. The first case was clearly post-traumatic but the diagnosis in the second case was more difficult. The authors discuss the aetiological diagnosis of these rare non-atheromatous aneurysms in adults and the therapeutic management with respect to these two cases and a review of the literature.

Coronary Angiography↗
PubMed1996

[Long-term development of aortic valve stenosis surgically treated at an advanced stage].

From January 1972 to June 1990, 112 patients (39 to 83 years old), 67 males and 45 females were submitted to surgery for sever calcified aortic stenosis. 68 patients were in NYHA III (60.72%) and 44 in NYHA IV. Early mortality included 8 patients (7.14%), 6 died for cardiac reasons. Late mortality was 27.67%. Actuarial survival rate (including postoperative mortality) was 88.39%, 77.67%, 67.85% and 65.17% at one year, five, ten and fifteen years, respectively. Results were significantly correlated to left branch block on preoperative EKG, episodes of complete heart failure, significant coronary stenosis, the cardioplegia technique and the association with coronary bypass.

Actuarial Analysis↗
PubMed1996

[A study of the 30 minutes following reperfusion after crystalloid and cold blood cardioplegia by enzymatic and metabolic analysis of coronary blood flow].

Post-ischemic reperfusion phenomena were studied in two methods of myocardial protection: crystalloid cardioplegia (St Thomas n(o) 2) and cold blood cardioplegia (Buckherg) during cardiopulmonary bypass for human myocardial revascularisation. Myocardial protection was assessed on the course of hemodynamic parameters, reperfusion arrhythmias and biochemical analysis of the coronary flow after cross-clamp removal: creatine phosphokinase (CPK-MB) and nucleotide adenine metabolites (adenosine, inosine, hypoxanthine, xanthine and uric acid). The study was performed in two groups of 14 patients. Hemodynamic conditions were similar in both groups during reperfusion in order to avoid different coronary flow. Under these conditions, myocardial protection by cold blood cardioplegia reduced reperfusion arrhythmias, and resulted in a loss of CPK-MB release. Furthermore, cold blood cardioplegia provided protection of myocardial energy metabolism by reducing the loss of metabolites, purine bases and oxypurine bases into the coronary sinus. Our results also show that hypoxanthine is probably the final product of ATP degradation in human myocardial tissue.

Aged↗
PubMed1996

Intracardiac air clearing in valvular surgery guided by transesophageal echocardiography.

BACKGROUND AND AIMS OF THE STUDY: Air embolism during open heart surgery seems to be a common occurrence and may be responsible for neuropsychological deficit or myocardial damage. MATERIAL AND METHODS: Forty-two consecutive patients undergoing valvular surgery were studied using the long axis view of the heart by two dimensional transesophageal echocardiography (TEE). The patients were randomized into two groups of 21 each. In group 1, the routine air evacuation method was used. In group 2, the same air evacuation method was used and controlled with a Doppler ultrasonic probe adjusted around the root of the aorta. At the end of air evacuation, intracardiac microbubbles and retained air were analyzed with TEE and when air was founded, its location was communicated to the surgeons who tried to remove it by shaking the heart and tilting the operating table for 15 minutes. The patients were assessed for detection of cardiac or neurological postoperative complications. RESULTS: The incidences of microbubbles and retained air were 57% and 43% in group 1, and 62% and 38% in group 2 respectively (ns). The mean grade of microbubbles was lower in group 2: 1.4 +/- 0.8 vs. 2.2 +/- 0.9, p < 0.05. TEE allowed to significantly decrease (p < 0.05) retained air and mean grade of microbubbles to 14% and 1.3 +/- 0.8 in group 1, and to 10% and 0.8 +/- 0.8 in group 2, without statistical difference between the two groups. Despite the help of TEE, manual attempts to eradicate retained air were unsuccessful in five patients (three in group 1, two in group 2). CONCLUSIONS: The use of aortic ultrasonic probe allowed to reduce the amount of microbubbles. TEE was a useful tool not only for the detection of retained air but also for locating it, and guiding the procedure to eliminate it.

Adolescent↗
PubMed1995

Subdiaphragmatic implantation of implantable cardioverter defibrillator generator.

Despite several improvements in the surgical technique and in the technologic design of cardioverter defibrillators made over the past years, abdominal placement of the generator device, done as Mirowski did it in his first implantation performed in 1980, remains the widely used method. Although smaller defibrillators are available, they remain bulky and are a source of local complications. To prevent such complications and to enhance patient comfort, we performed a subdiaphragmatic implantation in 31 patients.

Defibrillators, Implantable↗