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Biomedical subjects

B Letac

Publications and source records attributed to B Letac.

At least 37 records · Page 2Linked to original sources
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

Intraoperative coronary angioscopy--technique and results: a study of 38 patients.

Over a period of 11 months, 38 patients submitted to coronary artery revascularization underwent intraoperative angioscopy of the coronary arteries and internal thoracic arteries. Fifty-nine lesions were observed, but only 31 stenoses responsible for coronary insufficiency were observed (33%). Forty-four distal anastomoses were explored (47%) but ten of these explorations were incomplete. None revealed technical failure of the anastomosis. Thirteen harvested left internal mammary arteries were explored. One of the explorations led to rejection of the graft due to an intimal fracture. Some tiny intimal flaps were observed in our experience, as in others. Although the iatrogenic origin of these lesions in relation to the introduction of the angioscope is obvious, it does not seem to influence the outcome of the operation. In our opinion, two main fields appear to be developing in coronary angioscopy: preoperative assessment of the quality of internal thoracic artery grafts, and control of distal graft anastomoses. The flexibility of the angioscopes and of the leading catheters must be improved to minimize the risk of arterial wall traumatic lesions.

Angioscopes↗
PubMed1993

[Simplified continuity equation: absence of predictive value in assessing severity of mitral valve stenosis].

The object of this study was to assess the accuracy of the simplified continuity equation (SCE) defined as the ratio of velocity time integrals (VTI) of the aortic or pulmonary to mitral orifice in the evaluation of severe mitral stenosis. The results of the continuity equation and VTI ratios were compared with the Gorlin catheter valve area in 70 patients with pure mitral stenosis in sinus rhythm. The continuity equation (CE) and SCE were significantly correlated (p < 0.01) with the Gorlin surface area with a better coefficient with the CE (r = 0.86) than with the VTI ratio (r = 0.74). The patient population was divided into two groups depending on the severity of mitral stenosis; Group I had catheter valve areas of less than 1.5 cm2: 38 patients had mean value of the CE of 1.11 +/- 0.22 cm2 and of the SCE of 0.32 +/- 0.09. In Group II (mitral valve area > or = 1.5 cm2), 32 patients had a mean CE value of 1.92 +/- 0.29 cm2 and a SCE value of 0.56 +/- 0.14. Only two patients in Group I had SCE values greater than 0.5. Conversely, no patients in Group II had a SCE value of less than 0.3. For a range of SCE values of 0.3 to 0.5, there was an important overlap between the two groups (19 patients of Group I and 9 patients of Group II).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

[Current status of aortic valvuloplasty in patients aged 80 and over. Apropos of a recent series of 70 patients (1989-90)].

In contrast with aortic valve replacement, the treatment of choice for severe aortic stenosis because of the better long-term results, percutaneous aortic valvuloplasty, has only limited indications, mainly because of the high rate of restenosis. However, in very elderly patients, the surgical risk is high, sometimes prohibitive. For this reason, the authors report their latest results with this technique in a series of octogenarians. Between January 1989 and December 1990, 70 aortic valvuloplasties were performed in octogenarians (average age 85 +/- 3 years). The indications were advanced age > or = 85 years (46%), poor left ventricular ejection fraction < 40% (20%), secere associated coronary artery disease (3%), associated extracardiac pathology (11%), poor general condition (11%) or refusal of surgery (4%). The great majority of these patients (83%) were very symptomatic: 70.5% had Grade III-IV dyspnoea, 20% had Grade III-IV angina and 20% had syncopal attacks. Valvuloplasty reduced the mean transvalvular pressure gradients from 61 +/- 23 to 30 +/- 11 mmHg (p < 0.01) and increased aortic valve surface area from 0.53 +/- 0.19 to 0.94 +/- 0.12 cm2 (p < 0.001). There were two deaths (2.9%) in the catheterization laboratory and 4 (5.7%) complications during the hospital period (myocardial infarction: 1, cerebrovascular accident: 1, severe aortic regurgitation: 1 and complete atrio-ventricular block: 1). There were no serious vascular complications. The average duration of the hospital period was 6 +/- 5 days. Clinical follow-up of 17 +/- 7 months was obtained in 97% of patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1993

[Extensive isolated aneurysm of the right coronary vessel developing within 4 years].

The authors report the case of a 64 year old man on chronic haemodialysis therapy in whom coronary angiography showed a right coronary artery aneurysm. This patient had undergone coronary angiography 4 years previously and no aneurysm had been found on that occasion. The aneurysm occurred in the context of coronary atherosclerosis, coronary angiography showing typical appearances of double vessel disease. There were several special features of this aneurysm which contribute to the originality of the case: its rapid development within 4 years, its large size and the fact that it was an isolated finding on the right coronary artery. Several aetiologies are discussed but none can be formally confirmed.

Angina Pectoris↗
PubMed1993

[Electrophysiological evaluation of ventricular tachycardia].

The ability to induce and terminate ventricular tachycardia reproducibly by programmed stimulation has led to the development of electrophysiological investigations for the management of patients suffering from spontaneous arrhythmias. The investigation consists in introducing several multipolar catheter electrodes under local anaesthesia which are then positioned in contact with the endocardium in several regions of the heart. There is no consensus as to an ideal stimulation protocol for these patients but the basic principle is the introduction of one or several ventricular extrasystoles every 8 beats in sinus rhythm or during a controlled ventricular paced rhythm. At present, the major indication is rarely diagnostic in the presence of wide QRS complex tachycardias difficult to analyse by electrocardiography. On the other hand, electrophysiological investigations are highly recommended in cases of unexplained syncope in patients with documented or suspected heart disease, in symptomatic patients with intraventricular conduction defects in whom ventricular arrhythmias are suspected as the cause of symptoms or after cardiac arrest without transmural infarction or, for many teams, after the 48th hour of transmural infarction. Electrophysiological investigations are also justified in patients in whom surgical or catheter ablation of an arrhythmogenic focus is planned because of resistance to antiarrhythmic drug therapy. Evaluation of the efficacy of antiarrhythmic drugs by repeated investigations is common in the United States but is not so widely accepted in Europe.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Pacing, Artificial↗
PubMed1992

Repeat balloon aortic valvuloplasty.

This paper attempts to determine limitations and indications of performing a second balloon aortic valvuloplasty procedure (BAV2) because of restenosis, which is the major limitation of this technique. From September 1985 to December 1989, 357 patients underwent a primary BAV (BAV1) and 67 patients had a BAV2. Forty-two patients (group A) had repeat catheterization because they were markedly symptomatic 11 +/- 7 months after BAV1. Twenty-five patients (group B) came from a group of 73 patients who had been systematically scheduled for repeat catheterization in order to evaluate the hemodynamic restenosis rate 8 +/- 3 months after BAV. At time of BAV2 most of the patients of group A were severely disabled. Comparison of pre-BAV2 gradient and aortic valve area with pre-BAV1 measurements showed in a slightly less severe degree of aortic stenosis in group A and in group B with any difference in cardiac index and ejection fraction. Immediately following BAV2, the gradient decreased from 72 +/- 22 to 33 +/- 15 mm Hg (P less than 0.001) and aortic valve area increased from 0.56 +/- 0.18 to 0.85 +/- 0.28 cm2 (p less than 0.001) in group A. In group B, gradient decreased from 68 +/- 15 to 33 +/- 15 mm Hg (p less than 0.001) and aortic valve area increased from 0.70 +/- 0.16 to 0.90 +/- 0.25 cm2 (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Improved myocardial ischemic response and enhanced collateral circulation with long repetitive coronary occlusion during angioplasty: a prospective study.

OBJECTIVES: The goal of the study was to evaluate the progressive increase in ischemic threshold with multiple sequential transient coronary occlusions and to assess the role of the collateral circulation in adaptation to ischemia. BACKGROUND: It has been observed that the duration of balloon inflations during coronary angioplasty can be gradually prolonged during subsequent dilations with a reduction in patient symptoms and diminished ischemic electrocardiographic (ECG) changes. Although the mechanism has not been fully explained, recruitment of coronary collateral circulation induced by repeated coronary occlusion has been reported. The stimuli for recruitment and the natural history of coronary collateral circulation are not understood. METHODS: Seventeen patients with isolated stenosis of the left anterior descending coronary artery and a normal left ventricle were enrolled. Angioplasty consisted of five successive prolonged inflations. Sequential changes in clinical, intracoronary ECG and left ventricular indexes of myocardial ischemia were examined. Coronary collateral channels were evaluated during balloon inflations by ipsilateral and contralateral injections of contrast medium and hemodynamically by occlusion pressure. RESULTS: An improved tolerance to myocardial ischemia with repetitive coronary occlusions was demonstrated by a significant reduction of angina, ST segment deviation, left ventricular filling pressure and less impairment of ejection fraction. Left ventricular wall motion abnormalities remained unchanged. Collateral angiographic grade did not change in 7 patients and increased in 10. CONCLUSIONS: This study confirms a progressive adaptation of myocardial ischemia to repetitive coronary occlusions and supports the concept that sequential episodes of myocardial ischemia are a stimulating factor for the recruitment of collateral channels in humans. These results also suggest that enhancement of recruitable collateral circulation might be an underlying mechanism of myocardial ischemic preconditioning.

Adult↗
PubMed1992

Non-invasive assessment of mitral stenosis before and after percutaneous balloon mitral valvotomy by Doppler continuity equation.

The continuity equation was used to estimate non-invasively the stenotic mitral valve area by comparison with two other echocardiographic methods (planimetry and pressure half-time) and with Gorlin's formula as the gold standard. The accuracy of the equation of continuity was determined before and 24 h after valvuloplasty in a study group of 21 patients with severe mitral stenosis. According to the equation of continuity, mitral valve area was calculated by the product of the cross-sectional area and the aortic or pulmonary annulus and the ratio of the time velocity integral of the aortic or pulmonary flow to that of the mitral stenotic jet. In pre-valvotomy basal conditions, the Doppler continuity equation demonstrated significant correlations with 2D planimetry (r = 0.72, P less than 0.01), with the pressure half-time method (r = 0.62, P less than 0.01) and with the Gorlin formula (r = 0.66, P less than 0.01). There was no significant difference between the haemodynamic data and the echocardiographic measurements. Twenty-four hours after valvotomy, the Doppler continuity equation also demonstrated significant correlations with 2D planimetry (r = 0.83, P less than 0.01), with pressure half-time (r = 0.82, P less than 0.01) and with the Gorlin formula (r = 0.69, P less than 0.01). However, the haemodynamic measurements significantly overestimated (P less than 0.01) the echographic measurements. Thus, we conclude that the continuity equation provides an accurate estimation of mitral valve area in mitral stenosis before and after balloon valvotomy.

Adult↗
PubMed1992

[Prevalence and description of cardiac involvements in primary antiphospholipid syndrome].

In order to assess the prevalence of cardiac involvement in the primary antiphospholipid syndrome (PAS), a syndrome which associates thromboembolism, recurrent abortion, the presence of antiphospholipid antibodies and thrombocytopenia, transthoracic (TTE) and trans-esophageal echocardiography (TEE) was performed in 15 patients, 10 women and 5 men with a mean age of 38.8 +/- 11 years, with the PAS but without systemic lupus erythematosus. The presentation of the PAS was a thrombotic event (6 arterial and 7 venous) in 13 cases, and recurrent abortion in 3 cases. Twelve patients had high anticardiolipin antibody levels (> or = 15 U GPL) and 12 had a raised anti-prothrombinase antibody title. Valvular heart disease was detected in 9 patients (60%) as a valve thickening (> or = 5 mm for the mitral and > or = 3 mm for the aortic valve) or nodule. Mitral regurgitation was observed in 4 cases both on TTE and TEE and was mild in 3 cases and severe in 1 case. Aortic regurgitation was diagnosed in 6 patients, in 3 cases by TTE and in 6 cases by TEE. It was mild in 5 cases and moderate in the other cases. Pericardial effusion was observed in 3 patients (20%), alone in 1 case and associated with valvular disease in the other two cases. No abnormality of left ventricular systolic or diastolic function could be demonstrated. In conclusion, cardiac involvement seems to be common in the PAS, and TEE is a sensitive and accurate method for describing the valvular, especially aortic valve, abnormalities.

Abortion, Habitual↗
PubMed1991

Fluoroscopic guidance in transseptal catheterization for percutaneous mitral balloon valvotomy.

A percutaneous mitral balloon valvotomy (PMBV) was attempted on 190 patients with fluoroscopic guidance of atrial septal puncture for transseptal catheterization; in 3 cases, the procedure could not be performed. The left atrium was always reached on the first attempt, when the relationship of the Brockenbrough needle to the aortic catheter was previously observed in 3 fluoroscopic views: anteroposterior, 45 degrees right anterior oblique, and lateral. The atrial septal puncture site was located immediately below the aortic valve level, probably in the fossa ovalis, for the first 80 patients, and at mid distance between the aortic valve level and the diaphragm for the last 110. Hemodynamic data were similar in both groups. Fluoroscopic guidance for atrial septal puncture seemed capital for patients with scoliosis or in whom a vascular distortion (e.g., advanced pregnancy, right inferior vena cava absence) prevented a perfect parallelism between the needle curve and the needle outer index.

Adult↗
PubMed1991

Evaluation of restenosis after balloon dilatation in adult aortic stenosis by repeat catheterization.

To evaluate the restenosis rate after successful balloon aortic valvuloplasty, clinical evaluation and repeat catheterization were performed in 96 patients who had undergone balloon dilatation 7 +/- 5 months earlier. Restenosis, defined as a loss of greater than 50% of the benefit in aortic valve area obtained after balloon valvuloplasty, was observed in 48% of the patients. Actuarial analysis showed that the restenosis rate was time dependent and was 80% at 15 months. However, functional improvement was observed in most of the patients with or without restenosis. The restenosis rate was not correlated with the degree of enlargement of the aortic orifice produced by the valvuloplasty procedure. Because of the high incidence of restenosis, balloon aortic valvuloplasty should be limited to patients who have a contraindication to surgery or are at high risk for surgery, or as a bridge to surgery.

Actuarial Analysis↗
PubMed1991

The role of catheter ablation techniques in the treatment of classic (type 1) atrial flutter.

Several attempts at circuit interruption of type 1 atrial flutter by means of surgical or catheter techniques have been published. We recently reported the results of a series of patients who underwent catheter fulguration of the low septal right atrium, with a mean follow-up of almost 3 years. True electrophysiological success was observed in 7/14 patients (50%). Clinical success, defined as absence of symptoms, was observed in 8 was observed in 8/14 (57%) in this patient population. No serious complications were encountered, but the potential risks of DC shock, and the experience that we gained in right atrial mapping using this approach, led us to reconsider the role of atrial DC ablation in these patients. Additional studies assessing the meaning of fragmented electrograms, and identification of one (or of several) slow conduction areas of the reentrant circuit are ongoing.

Atrial Flutter↗