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Biomedical subjects

G Motté

Publications and source records attributed to G Motté.

At least 19 recordsLinked to original sources
PubMed1998

[Diagnostic criteria of ventricular tachycardia].

When ventricular tachycardia is very rapid or complicates cardiac disease it must be diagnosed as rapidly as possible so as not to delay treatment. A careful analysis of the surface electrocardiogramme is usually sufficient to distinguish ventricular tachycardia from other-wide QRS complex tachycardias when the widening is due to ventricular aberration. The diagnosis is easier when the start of the tachycardia is recorded or when the sinus rhythm is interspersed with ventricular extrasystoles of the same morphology as that of the tachycardia. Similarly, atrioventricular dissociation is diagnostic of ventricular tachycardia but its negative predictive value is weak. Extreme axial deviation of the QRS complexes, concording morphology in leads V1 or V2 and V6 and the analysis of the QRS complexes in the precordial leads nearly always enables identification of supraventricular tachycardia with aberration. On the other hand, the distinction between other causes of wide QRS complexes (supraventricular tachycardia with preexcitation or intraventricular conduction defects) remains difficult in the absence of a reference electrocardiogramme and the clinical context.

Electrocardiography↗
PubMed1997

Hemodynamic correlates of effective arterial elastance in mitral stenosis before and after balloon valvotomy.

This study had the purpose of documenting the hemodynamic correlates of effective arterial elastance (Ea; i.e., an accurate estimate of hydraulic load) in mitral stenosis (MS) patients. The main hypothesis tested was that Ea relates to the total vascular resistance (R)-to-pulse interval duration (T) ratio (R/T) in MS patients both before and after successful balloon mitral valvotomy (BMV). High-fidelity aortic pressure recordings were obtained in 10 patients (40 +/- 12 yr) before and 15 min after BMV. Ea value was calculated as the ratio of the steady-state end-systolic aortic pressure (ESAP) to stroke volume (thermodilution). Ea increased after BMV (from 1.55 +/- 0.63 to 1.83 +/- 0.71 mmHg/ml; P < 0.05). Throughout the procedure, there was a strong linear relationship between Ea and R/T: Ea = 1.09R/T - 0.01 mmHg/ml, r = 0.99, P = 0.0001. This ultimately depended on the powerful link between ESAP and mean aortic pressure [MAP; r = 0.99, 95% confidence interval for the difference (MAP - ESAP) from -18.5 to +4.5 mmHg]. Ea was also related to total arterial compliance (area method) and to wave reflections (augmentation index), although to a lesser extent. After BMV, enhanced and anticipated wave reflections were observed, and this was likely to be explained by decreased arterial compliance. The present study indicated that Ea depended mainly on the steady component of hydraulic load (i.e., R) and on heart period (i.e., T) in MS patients.

Adult↗
PubMed1997

[Radiofrequency ablation of accessory atrioventricular pathways].

Since its introduction at the beginning of the 1980s, radiofrequency ablation of accessory atrioventricular pathways has become method because of its excellent results and the indications have increased to cases in which only symptomatic improvement is the objective. These advances have been made possible by technical innovations to the generators of the radiofrequency current and, above all, to the ablation catheters which enable mapping nearly all the perimeter of the atrioventricular rings and reach all the accessory pathways irrespective of their site. The approach depends on the localisation of the accessory pathway but the criteria of mapping are the same: detection of a specific accessory pathway potential, precession or concordance (depending on the topography) of the initial peak of the endocavitary ventriculogramme and the onset of the delta wave on the surface ECG, QS morphology of the ventriculogramme on monopolar recording, shortest VA' interval in orthodromic reciprocating tachycardia for latent kent bundles. In specialised centres, the global success rate is 90 to 98% but certain sites, especially the right lateral pathways, are more difficult to attain. The complication rate is about 4% but it tends to decrease with the experience of the operating teams and close monitoring of the patients. However, there persists an uncertainty concerning potentially arrhythmogenic effects of the lesions induced which justifies restricting the indications in young children.

Arrhythmias, Cardiac↗
PubMed1997

[Classification and pitfalls of atrioventricular blocks].

Atrioventricular blocks may be classified according to their degree, their site and their aetiology. Assessing the degree of block is not always easy when the P waves are poorly visible and/or masked by the ventricular complexes. Affirmation that a 2nd degree block is a Mobitz II block requires examination of the ECG to differentiate it from "false" Mobitz II due to variable PP intervals or concealed hisian extrasystoles. Complete atrioventricular block is easy to define on the ECG but not always synonymous with totally blocked conduction and should be interpreted taking into account the frequency of escape beats. Determining the site of block is important as it has therapeutic implications; the type of block evaluated from the surface ECG also provides useful but not always decisive information. The investigation of the aetiology of the block is valuable for differentiating acute, transient blocks from chronic (permanent or paroxysmal) blocks, the former sometimes requiring temporary but rarely permanent cardiac pacing.

Body Surface Potential Mapping↗
PubMed1996

Initial and long-term evaluation of escape rhythm after radiofrequency ablation of the AV junction in 50 patients.

Between 1986 and 1994, 50 patients (mean age 63 +/- 13 years), 25 of whom had organic heart disease and presenting with atrial arrhythmias refractory to 5.6 +/- 1.6 antiarrhythmic drugs, underwent radiofrequency ablation (5 +/- 3 pulses by procedure; duration of pulses 50.5 +/- 32 s) of the proximal AV junction to create complete and permanent AV block. The escape rhythm was studied immediately after the procedure and during long-term follow-up. Immediately after the procedure, an escape rhythm was observed in 80% of the patients (junctional in 92%). Over a mean follow-up of 36 +/- 16 months in 47 patients (2 patients died before assessment of escape rhythm and 1 was lost to follow-up), an escape rhythm was present in 39 patients (83%) and absent in the remaining 8 (17%). The only significant difference between the two groups was the initial presence of an escape rhythm (P = 0.008). However, three patients with an initial escape rhythm had none during long-term follow-up. The initial presence of an escape rhythm as a predictive factor of its presence during follow-up had a sensitivity of 87%, specificity of 63%, positive predictive value of 92%, and negative predictive value of 50%. Thus, the absence of an escape rhythm during long-term follow-up causing pacemaker dependency was noted in 1 of 6 patients. This represents a limitation to this palliative treatment, which should be reserved for patients suffering from supraventricular tachycardias refractory to other treatments.

Adult↗
PubMed1995

[Electrocardiographic aspects of atrial fibrillations].

The electrocardiographic analysis of atrial fibrillation is usually easy. However, some cases may be difficult to interpret: the organisation and voltage of the fibrillation waves can be very variable leading to appearances of atypical flutter in cases with large "f" waves or, conversely, in cases with low voltage fibrillation, to those of sinus mode dysfunction. The ventricular response may be slow: the conduction is usually delayed in the atrioventricular node where concealed conduction plays an important role in determining the ventricular response. Regular ventriculogrammes correspond to a junctional or ventricular escape rhythms. Aberrant conduction in the His-Purkinje system may sometimes be observed after long diastoles (phase 4 block) but often terminates short, preceded by long cycles (phase 3 block). It is usually easy to differentiate them from ventricular ectopics or preexcitation by careful examination and application of classical diagnostic criteria.

Atrial Fibrillation↗
PubMed1995

[Double responses].

Double response is a rare electrocardiographic phenomenon requiring two atrioventricular conduction pathways with very different electrophysiological properties. Double ventricular responses are the usual manifestation: an atrial depolarisation (spontaneous or provoked, anticipated or not) is followed by a first ventricular response dependent on an accessory pathway or a rapid nodal pathway and then a second response resulting from sufficiently delayed transmission through a nodal pathway for the ventricles to have recovered their excitability when the second wave of activation reaches them. A simple curiosity when isolated and occurring under unusual conditions, particularly during electrophysiological investigation of the Wolff-Parkinson-White syndrome, the double response may initiate symptomatic non-reentrant junctional tachycardia when associated with nodal duality and repeating from atria in sinus rhythm. The functional incapacity and resistance to antiarrhythmic therapy may require referral for ablation of the slow pathway.

Atrioventricular Node↗
PubMed1994

[Electrophysiological mechanisms of ventricular arrhythmia in myocardial infarction].

In experimental models of coronary occlusion, the physiopathology of ventricular arrhythmias varies with its timing, there being three main phases: early, late and chronic. The early phase covers the first 30 minutes and is dominated by tachycardias and fibrillations resulting from multiple micro-reentry circuits which are the consequence of major changes in conduction and excitability created by acute ischaemia. These arrhythmias may be triggered by extrasystoles which have a different mechanism related to the injury current generated in the border zone between ischaemic and healthy cells. The late phase lasts about 72 hours: it is characterised by polymorphic ventricular extrasystoles and bursts of relatively slow ventricular tachycardia. Much more rapid tachycardia can be induced by stimulation. The origin of these arrhythmias is usually in the surviving Purkinje fibres of the subendocardium. The mechanisms are variable: abnormal automaticity, reentry or activity triggered by delayed after depolarisations. During the chronic phase, reentrant tachycardia is possible but only when induced by stimulation. Delayed conduction is the consequence of non-uniform antisotropism related to the disorientation of the myocardial fibres caused by fibrosis. In the clinical situation, most research has been centered on sustained monomorphic ventricular tachycardias of the chronic phase. Their mechanism is almost exclusively reentry (the circuits usually being located in the subendocardium) as suggested by the triggering and interruption of clinical tachycardias by stimulation, the recording of fragmented activation or prepotentials at the site of emergence of the tachycardia and the phenomena of pacing.

Arrhythmias, Cardiac↗
PubMed1993

Percutaneous double balloon valvuloplasty for stenosis of porcine bioprostheses in the tricuspid valve position: a report of 2 cases.

The feasibility and results of percutaneous double balloon valvuloplasty were evaluated in 2 patients with stenosis of porcine bioprostheses in the tricuspid valve position. The procedures were performed with a Trefoil 3 x 10 and a 15 mm balloon. Long inflations (4 and 3 minutes) were well tolerated. A significant immediate increase in the valve area, without significant valvular regurgitation, was achieved in both cases, from 0.65 to 1.15 cm2 in case 1 and from 0.9 to 1.65 cm2 in case 2. Both patients required valve replacement during the follow-up, at 14 and 21 months. There was no restenosis, but echocardiography showed right atrial thrombosis in case 1. Progressive restenosis with peripheral edema and increase of the mean doppler gradient occurred in case 2. The procedure is feasible, safe, and well tolerated. It provides significant immediate hemodynamic improvement, but it should be considered as a palliative technique since a normal valve area can not usually be obtained and a restenosis is likely to occur at midterm follow-up.

Adult↗
PubMed1993

Percutaneous coronary angioplasty in patients over 75 years old: immediate and mid-term results.

Ninety-five patients 75 years or older (range 75-90, mean 79) underwent PTCA from 1987 to 1991. Forty-two patients were 80 years or older. Forty-four had prior MI, 5% had prior coronary bypass surgery (CBS), 13% had a prior history of recent cardiac failure, and 81% (77/95) presented with unstable angina, refractory to intravenous treatment in 31 cases. The mean left ventricular ejection fraction was 62% (range 34%-80%). Thirty-nine percent had single vessel disease, 41% had two vessel disease, and 20% had three vessel disease. Coronary calcifications were present in 28%. A single vessel was dilated in 81 patients, two vessels in 14 patients; complete revascularization was achieved in 41%. The clinical angiographic primary success rate was 79% (75/95). There were five procedural deaths, five MI, five CBS and, ten hematomas. Follow-up data were obtained in 100% cases, with a mean follow-up duration of 12 months (ranging from 1-36). There were four deaths, one MI, and two CBS. Twenty percent (15/74) of patients had a second PTCA with a 73% success rate. Finally, 70% of the initial population was asymptomatic after first or second PTCA at mid-term follow-up. We conclude that PTCA is safe and effective in elderly patients, with 70% clinical success rate at mid-term follow-up in spite of frequent incomplete revascularization limited to the culprit lesion.

Aged↗
PubMed1993

[Diagnosis of ventricular tachycardia by electrocardiography].

In monomorphic wide QRS complex tachycardia, it is important to differentiate ventricular tachycardia from supraventricular tachycardia with aberration or preexcitation both from the prognostic and therapeutic view points. Atrioventricular dissociation with fusion complexes allows diagnosis of ventricular tachycardia but the negative predictive value of these criteria is low. Extreme QRS axis deviation, concordant morphological criteria in leads V1-V2 and V6 and analysis of the RS complexes in the precordial leads, nearly always enable supraventricular tachycardia with aberration. The distinction with other causes of wide QRS complex tachycardias (supraventricular tachycardia with preexcitation or with non-systematized intraventricular conduction defects) is much more difficult in the absence of a reference recording and depends more on the clinical context than ECG analysis.

Diagnosis, Differential↗
PubMed1992

[Thrombolytic agents in myocardial infarction: results of large mortality studies].

Large studies involving several thousand patients have clearly established the effectiveness of thrombolytic therapy in reducing mortality in the acute phase of myocardial infarction: the earlier the treatment, the greater this reduction. The value of late thrombolysis remains to be determined by further studies. This technique can be extended to the oldest subjects who benefit most from this type of treatment, bearing in mind that they are at a greater risk of neurological complications. The effectiveness of thrombolysis is partially dissociated from its effects on left ventricular function. Since the thrombolytic agents (streptokinase, anistreplase and recombinant tissue plasminogen activator) are equally effective in reducing mortality and neurological complications, it seems reasonable to use the cheapest of these drugs as initial treatment, except in some special cases.

Fibrinolytic Agents↗
PubMed1992

[Drug treatment of chronic ventricular arrhythmia].

The treatment of chronic ventricular arrhythmias depends on the severity and tolerance of the arrhythmia. Extrasystoles, even repetitive, in the healthy heart, are usually respected when asymptomatic or treated with betablockers in first intention when symptomatic. These drugs should also be proposed for patients with ischemic heart disease and non-sustained ventricular tachycardia, a situation in which Class I antiarrhythmics should be avoided. The prevention of sustained ventricular tachycardial may be empirical, with betablockers and/or amiodarone, or guided by the results of pharmacological tests during endocavitary electrophysiological studies.

Adrenergic beta-Antagonists↗
PubMed1992

[Efficacy and tolerance of propafenone in the prevention after a year of recurrent atrial arrhythmia. Results of a multicenter study of 114 patients].

One hundred and fourteen patients were included in an open multicenter trial of the prevention of atrial arrhythmias by propafenone and of the tolerability of this anti-arrhythmic agent after a year. The study population was divided into two groups: group I of 45 patients with only runs of arrhythmias and group II of 69 patients with a stable arrhythmia. Patients were seen again after 2 weeks, 3 and 6 months and 1 year. Holter records were obtained routinely in group I and at 6 months in group II. Treatment was stopped for inefficacy in 30 patients (10 of group I, 20 of group II), for intolerance in 10 patients (5 in each group) and for both in 3 patients (1 in group I, 2 in group II). Propafenone was considered to be effective and well tolerated in 55 per cent of patients, this success rate being identical in the two groups. Effectiveness persisted in a stable fashion at 1 year in those patients who responded initially.

Adolescent↗
PubMed1992

[How to evaluate the arrhythmogenic risk after myocardial infarction?].

The risk of sudden arrhythmic death after myocardial infarction is high, especially during the first months. The evaluation of this risk should be performed before hospital discharge in the same way as residual ischaemia and left ventricular function, which are independent risk factors for arrhythmia, are assessed. Holter monitoring provides information not only about ventricular hyperexcitability (especially the detection of unsustained ventricular tachycardia) but also about the activity of the autonomic nervous system by analysis of variations of the sinus rhythm, the decrease of which carries a poor prognosis. The search for an arrhythmogenic substrate requires signal averaged electrocardiography, but although the absence of late potentials carries a good prognosis, the positive predictive value of this investigation is very low. The association of non-invasive indices of poor prognosis greatly increases the probability of a major arrhythmic event; this may require consideration of programmed ventricular pacing, another method of substrate and risk assessment, which has the added advantage of sometimes indicating the most appropriate therapy.

Arrhythmias, Cardiac↗
PubMed1992

[Percutaneous ablation of atrioventricular junction by radiofrequency current in resistant atrial arrhythmia. Results of a series of 24 patients].

Catheter ablation of the atrioventricular junction may be proposed for the treatment of certain atrial arrhythmias resistant to antiarrhythmic therapy. One of the methods currently being evaluated uses radio-frequency energy which has certain advantages compared with direct current ablation because of the progressive and limited lesions it produces. This technique was used in 24 patients with atrial arrhythmias resistant to antiarrhythmic therapy. The radio-frequency energy was delivered without general anaesthesia with HAT 100 and 200 (OSYPKA) generators in the unipolar mode (average 17.4 watts) for an average period of 22.3 +/- 8 seconds. The catheter (8F USCI suction catheter in the first 18 patients and a 7F Polaris Mansfield, deflectable catheter with a large distal electrode in the remainder) was positioned at the nodo-hisian junction at a point where the two distal electrodes recorded a large atrial deflection and the smallest possible hisian potential. The conduction defects induced during the acute phase generally remain stable in cases of complete atrioventricular block and tend to regress in cases of incomplete atrioventricular block despite initial control of atrioventricular conduction. During follow-up (21 +/- 16 months), 14 patients (58%) remained in complete atrioventricular block, 4 patients (17%) had controlled atrioventricular conduction with an acceptable ventricular rate with associated previously ineffective antiarrhythmic therapy. Radio-frequency ablation was a failure in 6 patients (25%). There were no haemodynamic, rhythmic or ischaemic complications during the acute phase or during follow-up. These results suggest radio-frequency energy is a seductive alternative to direct current ablation for percutaneous modification of atrioventricular conduction in patients with refractory atrial arrhythmias. However, simple modulation of atrioventricular conduction gives aleatory results due to the tendency to regression during follow-up. On the other hand, complete atrioventricular blocks created by radio-frequency energy are generally definitive and are associated with a junctional escape rhythm which is usually stable.

Adult↗
PubMed1991

Methods and limitations of an experimental model of long QT syndrome.

An experimental model of the long QT syndrome has been developed in conscious dogs. This report discusses the methods used in its preparation and the strengths and weaknesses of the model. This new model is suitable for screening the bradycardia-dependent proarrhythmic effects of drugs and for studying the electrophysiology of "torsades de pointes." Permanent bradycardia (RR: 1558 +/- 83 ms) was obtained in 37 dogs by chemically-induced complete atrioventricular block. A 10% further increase of ventricular repolarization (QT: 306 +/- 7.0 ms to 331 +/- 5.5 ms) was obtained in 28 of these dogs by diuretic-induced hypokalemia. Diuretics, despite saline replacement, induced some degree of functional renal failure and extracellular volume losses. The QT interval increased although ventricular cycle length decreased slightly. These biological and electrophysiological parameters were reproducible except for a slow increase in plasma creatinine. Cardiac failure and sudden death rarely occurred. The most severe, but reversible, renal failure occurred in some dogs given the highest diuretic doses. Hypokalemia resulted in ventricular arrhythmias in only 6 dogs, 2 of them exhibiting runs of ventricular tachycardia and even "torsade de pointes" as their potassium levels fell below 2 mmol/L. The results of studies with several drugs using the model, with or without hypokalemia, or with bradycardia worsened by propranolol are analysed.

Animals↗