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Biomedical subjects

B Letac

Publications and source records attributed to B Letac.

At least 55 records · Page 3Linked to original sources
PubMed1995

Angioscopic evaluation of prolonged vs standard balloon inflations during coronary angioplasty. A randomized study.

UNLABELLED: To study the immediate effects of prolonged total balloon inflation during PTCA, 41 patients (44 lesions) with chronic stable angina were randomized for prolonged sequential inflations (three to five inflations of 3 to 5 min each, for a total duration of > or = 12 min, group 1, n = 20 lesions) or 'standard' sequential inflations (three to five inflations of < or = 1 min each, for a total duration of < or = 3 min, group 2, n = 24 lesions). The mean duration of total balloon inflation time was 958 +/- 129 s in group 1 vs 205 +/- 46 s in group 2. Results of angioplasty were assessed on both angiography and percutaneous transluminal coronary angioscopy performed immediately after the procedure. High quality imaging of the coronary lumen and lesion morphology was possible on angioscopy in all patients without any complications. Post-PTCA angiographic percent diameter stenosis was significantly less in group 1 compared to group 2: 26 +/- 10% vs 36 +/- 8% (P < 0.05). On angioscopy, flaps were seen in 16 patients in group 2, but in only six in group 1 (P < 0.02). There was no difference in the incidence of thrombi on angioscopy between the two groups (group 1: nine cases, group 2: 10 cases). Sensitivity of angiographic detection of flaps and thrombi was poor: 10% and 12% respectively. One patient in each group developed a longitudinal dissection, detected on both angiography and angioscopy. CONCLUSIONS: (1) prolonged sequential balloon inflations lead to less residual luminal stenosis after PTCA, with a decreased incidence of intimal flaps in comparison with standard inflations. (2) Post-PTCA transluminal coronary angioscopy is safe and offers better assessment of luminal effects of PTCA than angiography.

Adult↗
PubMed1995

Balloon aortic valvuloplasty in elderly patients at high risk for surgery, or inoperable. Immediate and mid-term results.

Although aortic valve replacement is undoubtedly the treatment of choice for aortic valve stenosis, balloon aortic valvuloplasty may represent the only possible treatment for some frail elderly patients who may have additional medical problems. We evaluated immediate and 1-year results of balloon aortic valvuloplasty in 86 patients > or = 80 years with severe aortic stenosis. Mean age was 84 +/- 3 years. Forty-four % were 85 years or older. Mean gradient decreased from 68 to 26 mm Hg and valve area increased from 0.53 to 0.96 cm2 (P<0.05). There were two per-procedural deaths. No local vascular complication was observed. During the follow-up (13 +/- 9 months), 27 patients died, four had repeat balloon aortic valvuloplasty and eight underwent aortic valve replacement. Persistent clinical improvement was observed in 78% of the surviving patients. One-year actuarial survival rate was 73%. Balloon aortic valvuloplasty appears to be a safe and valuable technique in cases where surgery cannot be performed or carries a very high risk.

Aged↗
PubMed1995

[Synchronized anterograde perfusion during percutaneous transluminal coronary angioplasty: preliminary clinical study].

A new circulatory system, "physiologic anteroperfusion system", has been developed and tested in 6 patients with significant proximal coronary artery stenosis. Prolonged and safe balloon inflation was possible without any ischemic signs. The system consists of an electronic cardiac synchroperfusor which, by activating a pulsatile unit, permits increased diastolic anteroperfusion of autologous blood under physiologic pressure through low-profile standard angioplasty catheters. This study reports the results obtained in 6 patients during proximal prolonged percutaneous transluminal coronary angioplasty. Four men and two women suffering from severe exertional angina pectoris, with normal resting left ventricular function, no collaterals and excellent apical two-dimensional four-chamber echocardiographic views were studied. After a 90 +/- 10 seconds of control occlusion under continuous monitoring of hemodynamics, electrocardiograms (3 to 4 leads), two-dimensional echo and chest pain grading, a second balloon inflation protected by the physiologic anteroperfusion system at a flow rate of 44 +/- 12 ml/min was performed for fifteen minutes. The ischemic signs present in the myocardium depending on the occluded artery were totally abolished during prolonged inflation protected by physiologic anteroperfusion system. All the patients were successfully dilated and were discharged from hospital the following morning without cardiac enzyme elevation or signs of central or peripheral hemolysis. Conclusion, in 6 patients with severe proximal coronary artery stenosis, safe prolonged proximal angioplasty without signs of ischemia was performed using a new simple physiologic anteroperfusion system, which allows active diastolic flow-pressure controlled autologous arterial blood perfusion, through standard low profile catheters.

Aged↗
PubMed1994

Results of percutaneous transseptal mitral commissurotomy in patients 40 years and above with those under 40 years of age: immediate and 5-year follow-up results.

Patients with mitral stenosis in Western countries are relatively old. It is anticipated that percutaneous transseptal mitral commissurotomy (PTMC) may have more complications and may not be as effective in this group of patient as in younger patients due to more calcification and fibrosis of the mitral valve. We analysed the clinical, hemodynamic, echocardiographic data in 296 consecutive patients divided prospectively into two groups; group 1 consisted of 184 patients > or = 40 years and group 2 of 112 patients < 40 years coming mostly from developing countries. The immediate gain in valve area was 2.18 +/- 0.61 cm2 in group 1 vs. 2.31 +/- 0.65 cm2 in group 2 (P = ns). The incidence of acute regurgitation requiring surgical intervention was similar in both groups. Follow-up data up to 5 years after PTMC was available in 170 patients (92.4%) in group 1 (mean 20 +/- 13 months) and 83 patients (74.1%) in group 2 (mean 29 +/- 17 months). Restenosis by Doppler method (valve area less than 1.5 cm2 with loss of at least 50% initial gain in valve area) was found in 33 patients in group 1 (29.2%) vs. 11 (14.9%) in group 2 (P < 0.05). Events free from death, need for mitral valve replacement or repeat PTMC at 5 year follow-up was 76% in group 1 vs. 87% in group 2 (P < 0.05). We conclude that the immediate effectiveness and acute complications of PTMC in patients 40 years and above are comparable to younger patients. Restenosis is clearly higher and there is a trend towards need for mitral valve replacement in patients 40 years and above at follow-up. However, the continuing benefit for the majority of the patients 40 years and above (76% free from adverse events) would suggest that PTMC is an appropriate treatment modality even in the older patients.

Adult↗
PubMed1994

Atrioatrial conduction after orthotopic heart transplantation.

OBJECTIVES: In two patients with orthotopic heart transplantation, the surface electrocardiogram suggested interaction between the donor right atrium and the recipient right atrium. An electrophysiologic investigation was performed to assess possible atrioatrial conduction. BACKGROUND: After orthotopic heart transplantation, both recipient and donor atrial activities are usually independent, but in humans they may synchronize for short periods during exercise. METHODS: Electrophysiologic recordings were made using standard techniques. The atrial electrode locations (anterior for the donor and posterior for the recipient right atria) were confirmed by fluoroscopy. Incremental and programmed donor and recipient right atrial pacing protocols were performed. RESULTS: Unidirectional conduction between native and graft atria occurred in both patients. This phenomenon was evident at rest, during normal sinus rhythm and at various pacing rates, resulting in frequent atrial bigeminy and trigeminy. CONCLUSIONS: Possible atrioatrial conduction after orthotopic heart transplantation may potentially be arrhythmogenic for the chamber where extrasystoles occur. This should be taken into account in attempting to devise new pacing modes if both atria are rendered electrically common.

Adult↗
PubMed1994

[Angioscopic evaluation of the immediate result of coronary angioplasty in relation to balloon inflation time].

The aim of this study was to assess the effects of coronary angioplasty on the intima with respect to the duration of balloon inflation by percutaneous angioplasty. Twenty-seven patients were randomized according to the total duration of balloon inflation: Group I "standard" duration (total duration < or = 3 min, N = 13) and Group II: prolonged duration (total duration > or = 12 min, N = 14); the type and distribution of the lesions were comparable in the two groups. The results of angioplasty were evaluated immediately after dilatation by angiography and angioscopy. Angioscopy was performed without failure or complications with perfect definition of the images in all cases. Angioscopy showed 1) intimal tears, 2) thrombi, 3) longitudinal dissections. A classification in three grades was used taking the apparent gravity of the lesions into consideration. The mean duration of balloon inflation in Group I was 205 +/- 45 s and 958 +/- 129 s in Group II. The residual stenosis was 36 +/- 8% in Group I and 26 +/- 10% in Group II (p < 0.05). Angioscopy showed the frequency of intimal tears to be twice greater in Group I (9 cases) than in Group II (4 cases) (p = 0.05). Intravascular thrombi were observed in 13 cases, 6 in Group I and 7 in Group II. One case of longitudinal dissection was observed in each group: only one of these two cases was detected at angiography. The authors conclude that repeated and prolonged balloon inflations improve the immediate results of angioplasty with less residual stenosis at angiography and a lower incidence of intimal tears at angioscopy.

Aged↗
PubMed1994

[Prevalence of intra-auricular thrombi detected by transesophageal echocardiography in patients with cardiac transplants].

The aim of this study was to determine the prevalence of intra-atrial thrombi or spontaneous contrast by transoesophageal echocardiography in patients who underwent cardiac transplantation by Lower and Shumway's technique. Transoesophageal echocardiography was performed in 52 transplant patients (43 men, 9 women: average age 51 years) with a high frequency biplane transducer. After surgery, all patients received platelet antiaggregant therapy. Despite this treatment, 4 patients had a sudden systemic embolic episode and were then placed on oral anticoagulants. All patients were in sinus rhythm at the time of the examination and some had signs of acute rejection on endomyocardial biopsy performed the same day. Spontaneous contrast was observed in 27 patients (52%) and was associated with thrombosis in 15 patients (29%). These thrombi were located in the left atrial appendage in 8 cases, on the left atrial posterior wall in 5 cases and on the left atrial sutures in 2 cases. None of these thrombi had been detected by transthoracic echocardiography. No significant difference was observed between those with and those without thrombosis with respect to left atrial dimensions, left ventricular ejection fraction, cardiac index, pulmonary pressures and the number of episodes of acute rejection. The 4 patients with a history of arterial embolism all had an intra-atrial thrombus. This study demonstrates a high incidence of spontaneous contrast and intracardiac thrombi in the dilated left atrium of patients transplanted by Lower and Shumway's technique. It also underlines the value of transoesophageal echocardiography in the follow-up of transplant patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Anticoagulants↗
PubMed1994

[Treatment of supraventricular arrhythmia by permanent cardiac pacing].

Most pacemakers are used for the treatment of bradyarrhythmias. However, a small number of pacemakers has been implanted for the treatment of supraventricular tachycardia resistant to medical therapy. The results of small reported series show long-term pacing to be effective in terminating reentrant atrial and junctional tachycardia. This has led to an improved quality of life and fewer hospital admissions in the majority of patients. Although there are a number of limitations to the widespread use of this mode of treatment, the development of pacing techniques has improved our understanding of the mechanism of termination of tachycardia which has been fully used in ventricular tachyarrhythmias. In addition to the curative treatment of sustained junctional tachycardia, pacemakers have been implanted to prevent the occurrence of new episodes with seemingly equally satisfactory results. However, cardiac pacing for this indication is much less common now because of the very good results obtained recently by radiofrequency ablation techniques. The prevention of atrial arrhythmias, vagally-induced atrial tachyarrhythmias and the bradycardia-tachycardia syndrome are good indications for permanent pacing. The prevention of atrial fibrillation in sinus node dysfunction by pacing is becoming more popular with the emergence of new modes (DDI and rate-adjusted modes) and original arrhythmia preventing algorithms. The discussion about the real efficacy of atrial pacing in sinus node dysfunction is disappearing as results of prospective randomised trials confirming this efficacy become available, especially in preventing atrial fibrillation.

Arrhythmias, Cardiac↗
PubMed1994

[Effects of repeated and prolonged inflations on immediate angiographic results and complications of coronary angioplasty. Prospective and randomized study].

The effects of the duration of balloon inflation on the immediate and mid-term results of angioplasty were assessed in a randomized study initiated in June 1992. To date, 239 lesions in 224 consecutive patients were allocated randomly into 2 groups according to the duration of balloon inflation: short duration (123 lesions): 3 or 4 successive inflations, each < or = 1 mn, for a total duration < or = 3 min; long duration (116 lesions): 3 to 5 inflations, each of 4 to 5 minutes each for a total duration > or = 12 min. Patients with acute myocardial infarction, restenosis and lesions of bypass grafts were excluded. Stenosis (% of reduction of the internal diameter) was calculated with a digitalised Philips DCI system. Success was defined by < 50% residual stenosis in the absence of severe complications: death, emergency bypass surgery, infarction and extensive and/or occlusive dissection. The baseline clinical, haemodynamic and angiographic parameters of the two groups were comparable. The residual stenosis after angioplasty in the "short duration" group was 33 +/- 11% and 29 +/- 11% in the "long duration" group (p < 0.05). The primary success rate was 75% in the "short duration" compared to 89% in the "long duration" group (< 0.001). Angiographic dissection after angioplasty was observed in 38 cases in the "short" but only in 17 cases in the "long duration" group (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Aortic valve replacement after aortic valvuloplasty for calcified aortic stenosis. A propos of 104 patients].

Between February 1987 and December 1990, 104 patients (48 men, 56 women) with an average age of 69 years, underwent aortic valve replacement (AVR) after one or several percutaneous aortic valve balloon dilatation. Thirty one patients were in Class II and 73 patients in Classes III and IV. Twenty two patients had angina (16 Class I-II, 6 Class III-IV) and 12 patients had syncope or near syncope on effort. The indications of valvuloplasty were: non-definitive contraindications of surgery or a surgical risk which was estimated to be excessive (46 patients), a personal choice (41 patients). Five patients underwent preoperative dilatation because of the high operative risk; 7 patients refused surgery and 5 patients were operated as an emergency (2 mas-sive aortic regurgitations, 1 left ventricular perforation, 1 cardiogenic shock, 1 endocarditis with cardiogenic shock). The inter-val between dilatation and surgery was on average 472 days. The patients were improved over an average period of 261 days. Apart form the emergency cases, the patients were operated because of restenosis. Surgery consisted of 53 mechanical and 51 bioprosthetic valve replacements. There was an associated procedure in 17 cases (17 single bypass grafts, 2 double bypass, 1 triple bypass graft, 1 left ventricular suture, 1 Bigelow procedure, 2 mitral valve replacements, 1 tricuspid annuloplasty, 1 carotid endarteriectomy, 1 replacement of the ascending aorta, 1 closure of ASD). The operative mortality was 7 patients (6.7%). The operative findings were 8 lesions related to dilatation, mainly valve tears or disinsertions requiring rapid (6 cases) or emergency (2 cases) surgery for massive aortic regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1994

[Ablation by radiofrequency in the treatment of atrial arrhythmia].

Atrial arrhythmias resistant to medical therapy are still a common indication for ablation of the normal atrioventricular conduction pathway (Tawara node and His Bundle). However, the development of catheter techniques of intra-atrial ablation to destroy arrhythmogenic myocardial zones enables radical cure of the arrhythmias with the respect of the nodo-hisian pathway. With respect to common flutter, a number of series, including our own, show a 50 to 75% long-term success rate. We believe that a very high success rate in the ablation of flutter will probably be achieved in a reproducible manner but this will require a more accurate understanding of the tachycardia circuit and technological developments allowing controlled radio-frequency destruction of bigger atrial myocardial zone. Experience of radio-frequency ablation atrial of atrial extrasystoles is more limited than that of flutter and there are fewer published series. Globally, catheter ablation of atrial tachycardia remains a more difficult and a less well codified procedure than that of accessory pathways or of intra-nodal reentry. Radio-frequency ablation in this indication is not without danger in view of the thinness of the atrial wall. We believe that radio-frequency catheter ablation for atrial arrhythmias should, for the moment, be reserved for centres specialised in the techniques of electro-physiological investigation and ablation.

Atrial Flutter↗
PubMed1993

Progressive decrease in myocardial ischemia assessed by intracoronary electrocardiogram during successive and prolonged coronary occlusions in angioplasty.

Progressive decrease in chest pain and surface ECG changes are commonly observed during successive balloon inflations in coronary angioplasty, which suggests a decrease in myocardial ischemic response. To assess this hypothesis, we continuously recorded intracoronary ECGs during four balloon inflations; each of the inflations was maintained to a minimum of 120 seconds in 19 patients who had significant stenosis in the left anterior descending artery and normal left ventricular function. Three successive QRS-T complexes were analyzed on surface and intracoronary ECGs for measurements of ST-segment elevation 60 milliseconds after the J point. Surface ECG changes were compared with intracoronary ECG changes. On intracoronary ECG, ST area (in square millimeters) and T wave amplitude (in millimeters) were also computed. Chest pain was noted as present or absent during each successive balloon inflation. Ability of intracoronary ECG to detect myocardial ischemia, which was defined as ST-segment elevation greater than 1 mm during balloon inflations 1 to 4, was 89%, 89%, 84%, and 74%, respectively and was higher than that of surface ECG, which was 68%, 63%, 68%, and 58%, respectively. On intracoronary ECG, when compared with the first balloon inflation, a significantly smaller increase in ST-segment elevation was noted during each subsequent balloon inflation, whereas a significantly smaller increase in ST area and T wave amplitude was noted only during balloon inflation 4. The number of patients who experienced chest pain decreased from 15 to 13, 10 and 6 from the first to the fourth balloon inflation. This report demonstrates a progressive decrease in myocardial ischemic response during successive and prolonged balloon occlusions.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗