Search PubMed⌕ Search

Biomedical subjects

B Letac

Publications and source records attributed to B Letac.

At least 109 records · Page 6Linked to original sources
PubMed1988

[Bundle branch reentry tachycardia: a possible mechanism of flecainide proarrhythmia effect].

A 42-year old man with non-obstructive myocardiopathy complicated by paroxysmal atrial fibrillation treated with amiodarone (200 mg per day) received flecainide in daily doses of 400 mg for undocumented palpitations. Ten syncopes and numerous malaises occurred during the following two months. Electrophysiological testing was performed, showing prolongation of HV to 80 ms and discreet widening of QRS to 100 ms. Programmed atrial stimulation failed to demonstrate a second degree subnodal block and to induce tachycardia. In contrast, ventricular stimulation elicited a critical SH delay (260 ms), always followed by a left delay-type complex preceded by His bundle deflection which suggested reentry within the His-Purkinje system. Three extrasystoles on imposed rhythm started sustained ventricular tachycardia with the same 270 ms cycle morphology and reproducing the symptoms. Each V wave was preceded by an H potential, with HV varying from 100 to 300 ms. Three weeks after flecainide was discontinued, HV was 60 ms, and no ventricular tachycardia could be triggered by programmed stimulation. The patient remained symptom-free throughout the 5-month follow-up. This case illustrates the proarrhythmic effect of the flecainide-amiodarone combination. The mechanism of provoked tachycardia probably involves ventricular reentry through the His bundle branches, induced by a critical depression of conduction below the His bundle.

Amiodarone↗
PubMed1988

Two years' experience of percutaneous balloon valvuloplasty in aortic stenosis.

To provide an overview of our experience with percutaneous balloon valvuloplasty in aortic stenosis, the results obtained in 218 patients have been analyzed. During the two years of its use, the technique of the procedure has been subsequently modified with increasing balloon diameters, initially 15 mm, 18 mm and then 20 mm; currently, a balloon diameter of up to 23 mm or even two balloons may be used. Accordingly, in our last 70 patients, significantly larger valve orifice areas have been achieved. The mean postinterventional valve orifice area was 1.06 cm2. In 73% of the patients valve orifice area was 0.9 cm2 or greater, in 60% 1 cm2 or more. In consideration of the high prevalence of elderly, severely-ill patients in our series, the in-hospital mortality of 4.5% (ten of 218 patients) was relatively low. Nonfatal complications included stroke in three, tamponade in three, and myocardial infarction in one patient with severe coronary artery disease. In 25 patients (13%) there were bleeding complications at the site of vascular puncture, nine of which required surgical revision. Valvuloplasty usually did not result in worsening of aortic incompetence and, consequently, up to grade II regurgitation need not be considered a contraindication. Follow-up data was obtained at an average of eight months (three to 18 months) after the procedure in the first 148 patients. During this period, 24 patients had died, 19 of whom were in functional class IV and all of whom had impaired left ventricular function and residual severe aortic stenosis after the procedure. Most of the survivors were stable and had marked clinical improvement.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1987

Percutaneous transluminal balloon valvuloplasty of adult aortic stenosis: report of 92 cases.

Percutaneous transluminal balloon valvuloplasty was attempted in 92 adult patients with severe calcific aortic stenosis. The mean age was 75 +/- 11 years (range 38 to 91) and 35 patients were more than 80 years old. Most of the patients were severely disabled; 66 were in New York Heart Association functional class III or IV, 27 had syncopal attacks and 21 had severe angina pectoris. Because of unacceptably high surgical risk or contraindication to thoracic surgery, 42 patients could not be considered for valve replacement. Other patients either were in a category of high operative risk or refused the surgical intervention. Valvuloplasty was performed by way of the femoral route (82 patients) or the brachial route (10 patients). Catheters of size 15, 18 and 20 mm were successively placed across the aortic valve and three inflations were usually done with each of them, lasting 80 seconds on average, until a decrease in peak to peak systolic pressure gradient to 40 mm Hg or less was attained, a result considered satisfactory. The inflated balloons were not totally occlusive in most cases and clinical tolerance of inflation was good. Valvuloplasty resulted in a reduction of mean systolic gradient from 75 +/- 26 to 30 +/- 13 mm Hg (p less than 0.001); the final gradient was less than 40 mm Hg in 78 patients. Mean calculated aortic valve area increased from 0.49 +/- 0.17 to 0.93 +/- 0.36 cm2 (p less than 0.001). Immediately after the procedure, ejection fraction increased from 48 +/- 16 to 51 +/- 16% (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Unusual electrocardiographic patterns of modulated parasystole.

Modulation of a parasystolic rhythm implies that the latter is affected by nonparasystolic beats in predictable ways. When modulation occurs the diagnosis of ventricular parasystole cannot be made by applying the well-known 'classical' criteria. This report deals with clinical tracings from three cases having modulated parasystole with unusual characteristics. Case 1 showed a 24-hour diurnal variability of parasystolic modulation characterized by its occurrence during only part of the period of sleep (from 1 to 5 am). In case 2, modulated ventricular parasystole produced episodes of intermittent ventricular bigeminy with fixed coupling resembling those attributed to a reentry mechanism. The proper diagnosis was made when the sinus cycle length changed abruptly. Finally, in case 3, the idionodal rhythm from a patient with complete AV block was shown to be not only parasystolic, but also modulated. In addition, the idionodal rhythm was entrained (captured) in a concealed fashion by paced beats so that the post-pacing events did not conform with those occurring during overdrive pacing of parasystolic nonmodulated, or nonparasystolic, idionodal rhythms. These findings constitute the clinical counterpart of experimental studies performed with microelectrode techniques.

Adult↗
PubMed1987

Intravenous anisoylated plasminogen streptokinase activator complex versus intravenous streptokinase in evolving myocardial infarction. Preliminary data from a randomised multicentre study.

The efficacy of a single intravenous bolus of anisoylated plasminogen streptokinase activator complex (APSAC 30U in 4 to 5 minutes) versus an intravenous infusion of streptokinase (1.5 X 10(6) U in 60 minutes) was assessed in 86 patients with evolving myocardial infarction of less than 6 hours duration in a cooperative randomised study. The patency of the infarct-related artery was assessed by coronary angiography at, on average, 90 minutes after therapy (mean time: APSAC 95 minutes, streptokinase 105 minutes). The treatment groups were similar with respect to sex, age, location of myocardial infarction and the delay from onset of pain to treatment. The 90-minute patency rate (grade 2 to 3) was 71.8% in the APSAC group and 55.8% in the streptokinase group; the difference was not statistically significant. There was no difference between the drop in fibrinogen concentrations in the 2 groups at 3 or 24 hours. The minimal concentration obtained at the first assessment was +/- 0.2 g/L in the streptokinase group and 0.5 g/L in the APSAC group. One patient in the APSAC group, who had a previous meningeal bleeding, had a non-fatal cerebrovascular accident. In a subgroup of 38 patients who had 3 control coronary angiograms at 90 minutes, 24 hours and 3 weeks, the patency rate was 63, 82 and 93%, respectively, in the APSAC group and 48, 88 and 92%, respectively, in the streptokinase group (the difference was not statistically significant). None of the patients in the APSAC group presented with reocclusion, whilst 3 patients in the streptokinase group had reocclusions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

[Circadian variations and modification of ventricular parasystole].

As shown by Jalife and Moe, brief subliminar depolarizations induced upstreams of the protection zone may predictably modify the discharge from a parasystolic focus. In the biological and mathematical models of parasystole, numerous arrhythmias which do not fulfil the classical criteria of parasystole have been identified, some of them even mimicking a re-entry mechanism. In this paper we report the electrocardiograms of three patients in whom an electrotonic modulation mechanism may be involved. In the first patient the classical pattern of continuous parasystole without exit block was observed throughout daytime. However, between 1 and 5 a.m. non parasystolic beats lengthened or shortened the parasystolic rhythm, depending on their time-related position in the cycle. Later, the usual continuous parasystole pattern reappeared. In the second patient the patent 1:1 entrainment of parasystole by sinus beats resulted in long episodes of ventricular bigeminy with fixed coupling. A sudden slowing down of the cardiac rate disrupting the harmony of the two rhythms and, consequently, the regular entrainment of the ectopic focus, shortened the parasystolic cycle and suppressed bigeminy. In the third patient ventricular stimulation produced a hisian parasystolic rhythm resembling intermittent parasystole on surface ECG. It is concluded that, as suggested by experimental models, many disorders of cardiac rhythm which do not fulfil the criteria of parasystole can be explained in terms of modulated parasystole.

Adolescent↗
PubMed1987

[Gap, phase III and IV block and supernormal conduction of the right bundle branch].

A recent review of the literature corroborated that several factors explained why supraventricular impulses falling gradually earlier in the cycle could traverse the His-Purkinje system while other impulses occurring later could fail to do so. The present report deals with the coexistence (in the same patient) of three distinct mechanisms whereby progressively more premature impulses could be "unexpectedly" conducted. Phase III left bundle branch block coexisted with the following conduction disturbances in the right bundle branch; late "pseudosupernormal" conduction sandwiched in between periods of phase III and phase IV block; intermediate "pseudosupernormal" conduction resulting from the so-called type 2 gap, during which propagation occurred, but with H-V intervals longer than later in the cycle; early "true" supernormal conduction (related temporarily to the end of the T wave) exposed when a premature ventricular beat reached the affected zone in a concealed retrograde fashion. These findings show how, with block late in the cycle, conduction in earlier part of the cycle was not always due to "true" supernormal conduction.

Aged↗
PubMed1987

[Foreign body in the tricuspid valve with valvular insufficiency and right-left shunt].

We present the case of a 50-year old man who progressively developed tricuspid valve insufficiency with opening of a patent foramen ovale responsible for right-to-left shunt with polycythaemia. The tricuspid valve insufficiency was due to a foreign body, probably of surgical origin as suggested by its radiological image and by the patient's previous history. It would have been introduced, far away from the tricuspid valve (compound fracture of the wrist), several years previously. At surgery, we found the foreign body embedded in the valve system. As a possible mechanism for the mutilation, an undiagnosed endocarditis was suspected but could not be confirmed. Three cases tricuspid endocarditis (with foreign bodies in the right ventricle) and 3 cases of asymptomatic tricuspid valve foreign bodies have been published. Fifty-five cases of foreign bodies introduced peripherally and migrated into the heart, the pericardium and the pulmonary artery are reviewed.

Coronary Circulation↗
PubMed1987

[Systemic and coronary hemodynamic effects of intravenous nicardipine at rest and in ischemia induced by rapid atrial stimulation].

The systemic and coronary haemodynamic effects of intravenous nicardipine were investigated in 10 patients with a more than 70 p. 100 stenosis of the left coronary artery. Two brief atrial pacing tests (ST1 and ST2) were performed. ST2 was performed 30 minutes after an intravenous injection of nicardipine 2.5 mg over 5 minutes. Nicardipine produced a 25 p. 100 decrease in ventricular systolic pressure and a substantial increase in cardiac index (from 2.74 +/- 0.48 to 3.46 +/- 0.35 l/min/m2, p less than 0.001). Measurement of the coronary flow rate by the thermodilution method showed a 40 p. 100 increase in sinus blood flow while coronary resistance decreased not only in territories with normal supply but also in myocardial territories distal to the coronary stenosis (from 2.76 +/- 2.3 to 1.83 +/- 1.5 mmHg/ml, p less than 0.02). With the same paced heart rate the ventricular function parameters were significantly improved during ST2 (cardiac index ST2 3.56 +/- 0.65 vs ST1 2.8 +/- 0.48, p less than 0.001; dp/dt max ST2 2143 +/- 369 vs ST1 1874 +/- 301 mmHg/sec, p less than 0.05), reflecting a lower degree of myocardial ischaemia. This was confirmed by the lower amplitude of electrocardiographic depression and by a higher lactate extraction coefficient (LE ST1 6 +/- 7 p. 100 vs LE ST2 12 +/- 12 p. 100, p less than 0.05). Mean arterial blood pressure and coronary sinus blood flow rate values were identical during the two atrial pacing tests.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

[Congenital aortic valve stenosis treated by dilatation. Apropos of a case with hemodynamic control 12 months later].

Intraluminal dilatation of congenital aortic valve stenosis was attempted in a 14-year old boy. Significant improvement was obtained, with a fall in transaortic gradient from 80 to 30 mmHg. A control haemodynamic examination performed 12 months later confirmed that the result was stable; there was no aortic leakage, and myocardial hypertrophy had begun to regress at echocardiography. This case is of interest in that dilatation is less costly than surgical commissurotomy. However, this technique cannot be widely used until satisfactory long-term results have been demonstrated in a large population of children.

Adolescent↗
PubMed1987

[Comparison of the effects of ajmaline and procainamide in the diagnosis of paroxysmal atrioventricular block].

14 suspected of having a paroxystic atrio-ventricular block underwent a complete electrophysiological exploration including an ajmaline test. It was administered at the standard dose of 1 mg/kg at the rate of 1 mg/s. In order to evaluate a replacement test, an equivalent dose of procainamide was injected at the same rate (10 mg/kg, 10 mg/s) a few hours later. In 4 out of 14 cases the ajmaline test was positive. In only one patient, procainamide was able to demonstrate a sub-nodal block. The maximal lengthening of HV occurred at an earlier time after ajmaline than after procainamide (2.2 +/- 0.75 min. versus 4.1 +/- 1.59 min, p less than 0.02) and certainly more clear-cut (MaxHV = 73.5 +/- 12.9 ms versus 59.5 +/- 12.1 ms, p less than 0.01). The lengthening of HV after administration of these two products was significantly correlated but always markedly lesser with procainamide. In conclusion, the procainamide is less sensitive than the ajmaline test in the positive diagnosis of paroxystic atrio-ventricular blocks concerning absolute criteria in the positive diagnosis as well as relative criteria such as a definite lengthening of HV with ajmaline.

Aged↗
PubMed1986

[Treatment of unstable angina. A randomized double-blind study of propranolol, diltiazem and molsidomine].

A randomized, multicentric, double blind study attempted to compare in 41 patients hospitalized for unstable angina, the efficacy of diltiazem (D) 240 mg/day, propranolol (P) 160 mg/day and molsidomine (M) 8 mg/day. The patients included in the study presented one or several spontaneous angina episodes accompanied by a transient and significant lowering of ST and/or an inverted T wave without necrosis. The evaluation criteria were the occurrence of new angina pain and electrical alterations on a continuous Holter for 5 days. 11 patients received diltiazem, 13 patients received propranolol and 15 patients received molsidomine (including an early death). Clinically, the number of painful episodes per day and per patient goes, in an average, from 1.2 to 0.23 diltiazem, from 2.2 to 0.44 for propranolol and from 2.2 to 0.45 for molsidomine. Pain disappeared on the 5th day in 54.5 per cent of patients under diltiazem, 58.8 per cent of patients under propranolol and 53.5 per cent of patients under molsidomine. Electrically, the number of ischemic accidents per day and per patient was 0.45 under diltiazem, 2.12 under propranolol (0.53 in excluding one patient with latent angina) and 0.81 under molsidomine. The number of patients without any ischemic accident was 63.6 per cent under diltiazem, 53.8 per cent under propranolol and 40 per cent under molsidomine. In conclusion, diltiazem, propranolol, and molsidomine have a comparable efficacy in unstable angina. The association of these medications could have a synergistic effect.

Angina Pectoris↗