[Continuing education of the cardiologist].
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Cardiology↗
Biomedical subjects
C Guérot
Publications and source records attributed to C Guérot.
[Compensatory enlargement versus chronic constriction. The two features of vascular remodelling after experimental angioplasty].
Considerable efforts have been made to prevent post-angioplasty restenosis targeted mainly against a pathogenesis suggesting a dominant role of hyperplasia. We and others have already shown that constrictive remodelling plays a major role in restenosis. This article evaluates not only the constrictive remodeling theory but also compensatory enlargement associated with prevention of restenosis. The present study on 33 rabbits used the following protocol. Four weeks after inducing an atherosclerotic lesion by air-dessication of a femoral artery segment and a high cholesterol diet, angioplasty was performed. The angiographic minimal luminal diameter significantly increased after angioplasty. Three to four weeks later, initial gain was significantly lost. Restenosis was quantified histologically as well as a remodelling index and a hyperplasia index. No correlations were observed between degree of stenosis and hyperplasia present at the same degree in animals with and without restenosis. On the other hand, there was a strong correlation between restenosis and constrictive remodelling, and with absence of restenosis and compensatory enlargement. Moreover, there was significant a correlation between the degree of hyperplasia and the compensatory remodelling. These data point to the double nature of remodelling: compensatory enlargement observed in animals without restenosis, and constrictive remodelling, the principal mechanism observed in animals with restenosis.
Angioplasty, Balloon↗
[Paradoxes and constraints of medical progress].
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Cardiology↗
Remodelling: therapeutic opportunities.
Restenosis after angioplasty has been recently attributed to a lack of compensatory enlargement and/or chronic constrictive remodelling, rather than neointimal growth. Also, restenosis occurring after stent has been clearly related to neointimal growth. This clarification has dramatically helped in designing strategies targeted against the appropriate mechanisms. The mechanism of stent-related restenosis has been the most studied and several antiproliferative agents including gene therapy and radioactive stents have been successfully tested. Constrictive remodelling has been identified more recently and its pathophysiological mechanism remains poorly understood. Control of extracellular matrix metabolism might be an important pathway. Moreover, detection of the arteries that will 'enlarge' should avoid any preventive strategy including systematic stenting.
Adaptation, Physiological↗
Rotational atherectomy with adjunctive balloon angioplasty versus conventional percutaneous transluminal coronary angioplasty in type B2 lesions: results of a randomized study.
A randomized pilot study was performed comparing conventional balloon angioplasty (percutaneous transluminal coronary angioplasty [PTCA] group) and rotational atherectomy (RA) with a medium size burr (50% to 70% burr/artery ratio) with systematic adjunctive balloon angioplasty (RA group) in type B2 stenosis. A total of 64 patients were included. Primary success was 93.7% in the RA group and 87.5% in the PTCA group (p = NS). Technical failure with no complication occurred once in each group. Acute complications occurred in three patients in the PTCA group and in one in the RA group. Angiographic restenosis rates were similar (RA group: 39%, PTCA group: 42%, p = NS) with a follow-up rate of 93%. In type B2 lesions, when compared with conventional angioplasty, RA with systematic balloon angioplasty does not seem to increase procedural success, and the restenosis rate remains comparable. However, these results must be confirmed in a larger series of patients.
Aged↗
Prospects for gene therapy in cardiovascular disease.
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Cardiovascular Diseases↗
[Should a main coronary artery be dilated when the controlateral vessel is occluded?].
Angioplasty of the dominant left anterior descending or right coronary arteries when the controlateral artery is occluded may lead to major left ventricular dysfunction or cardiogenic shock. The authors assessed the results of angioplasty of a right coronary (n = 52) or left anterior descending (n = 141) artery stenosis when the controlateral artery was occluded and the left circumflex had no significant stenosis in 193 patients. The immediate and late (33 +/- 18 months) results were compared in 3 groups: the study group, a reference surgical group in which patients with comparable coronary lesions underwent double coronary artery bypass and a reference angioplasty group (n = 194) in which patients were treated by angioplasty of the right coronary and left anterior descending arteries. The left ventricular function of the study group was normal or midly abnormal in 72% of cases and moderately to severely abnormal in 28% of cases. During the hospital period, for the study group, there were 5.7% emergency coronary bypass procedures and 2.6% non-emergency bypass procedures, 1.6% of myocardial infarction and 0.5% deaths. After hospital discharge, the study group had 13.1% of coronary bypass procedures, 3.7% of myocardial infarcts and 4.7% deaths. The death and infarction rates were comparable in the 3 groups. The study group had a higher incidence of coronary bypass surgery in and after the hospital period than the control surgical group (p = 0.0.002). The authors conclude that dilatation of a main coronary artery when the controlateral artery is occluded is as safe as double coronary artery bypass surgery and angioplasty of the two vessels. Incomplete revascularisation in the study group did not affect survival rate without myocardial infarction compared with the angioplasty and surgical reference groups.
Actuarial Analysis↗
[Three-dimensional echocardiography. Principles and applications].
Three-dimensional echocardiography is based on two methods of retrospective reconstruction from two-dimensional echocardiographic images. The acquisition of the two-dimensional images may be free or imposed, the transducer either carrying an emission-reception system or fixed to an articulated support providing data about its position. In the first system, manual tracing of the contours of the region of interest performed on each frame are superimposed after time sequencing (using the ECG) and spatial repositioning, so enabling three-dimensional visualisation of the contours of the cardiac structures: this approach provides reliable quantitative information (volumes, mass and ejection fractions) and has led to the redefinition of the echocardiographic criteria of mitral valve prolapse. The second system is based on equidistant sections obtained by progressive, controlled two-dimensional scanning (parallel, arc of a circle and rotational) of the structure of interest: a value of grey scale is assigned to the space between two adjacent pixels, enabling the formation of voxels which, when superimposed, give the required effects of volume and surface for three-dimensional imaging. It is then possible to obtain any section of the volume and simulate surgical views of the beating heart. This approach may significantly improve diagnostic accuracy compared with two-dimensional echocardiography and provides access to new quantitative and qualitative parameters.
Echocardiography, Doppler, Color↗
[Dynamic cardiomyoplasty: models of action and indications].
Cardiomyoplasty, proposed as an alternative to cardiac transplantation for the first time in 1985, has been carried out in over 500 patients over the world. The functional improvement after the procedure may be spectacular. The haemodynamic improvement at rest is generally small in terms of pre and postoperative ejection fractions. A dynamic effect of systolic assistance due to stimulation of the latissimus dorsi may be demonstrated in some cases by analysis of ventricular pressure-volume curves. However, it is probable that cardiomyoplasty prevents ventricular remodelling (girdling effect) and that chronic stimulation of latissimus dorsi, necessary to prevent atrophy and fibrosis, reduces wall stress. Therefore, many mechanisms, probably associated, may explain the clinical efficacy of cardiomyoplasty. Though the contraindications of this technique are now better known, its role with respect to cardiac transplantation in cases of severe congestive cardiac failure resistant to medical therapy still remain undefined.
Cardiomyoplasty↗
Clinical study of the effects of latissimus dorsi muscle flap stimulation after cardiomyoplasty.
BACKGROUND: Beneficial hemodynamic effects after dynamic cardiomyoplasty have been inconsistently demonstrated, and the effects seen may be due to the wrap itself, to flap stimulation, or both. The aim of this study was to determine whether flap stimulation per se acts as a systolic active process after cardiomyoplasty. METHODS AND RESULTS: Catheterizations were performed in 13 patients 14.4 +/- 7 months after cardiomyoplasty. New York Heart Association functional class decreased from 3.3 to 2.1 after the procedure (P = .0005). Hemodynamic evaluations were first performed with the stimulator on in the 2:1 mode and then after the stimulator had been off for at least 24 hours. Left ventricular (LV) ejection fraction increased from 25.1 +/- 6% before surgery to 28.2 +/- 6.7% with the stimulator on after cardiomyoplasty (P = .04). When stimulation was stopped, there was no change (P > .05) in indexes of systolic or diastolic LV function (peak systolic LV pressure, LV ejection fraction, peak positive dP/dt, peak negative dP/dt, or tau). Pulmonary capillary wedge pressure and cardiac index were unchanged when stimulated and nonstimulated settings were compared (P > .05). However, a remarkable heterogeneity of individual responses was observed. Ejection fraction and cardiac index decreased with the stimulator off in 3 patients, but peak positive dP/dt decreased in 6 patients; diastolic function deteriorated in 2 patients, but a slight improvement was noted in 3 patients. Cardiothoracic ratio, echocardiographic LV end-diastolic dimension, and fractional shortening remained unchanged between immediate (< 1 month) and long-term (36.7 +/- 25.9 months) postoperative evaluations. CONCLUSIONS: In the majority of our patients, there was no short-term hemodynamic benefit of flap stimulation; therefore, we conclude that the efficacy of cardiomyoplasty may be a consequence of a passive "girdling effect," which limits the progression of ventricular enlargement and further deterioration of ejection fraction.
Adult↗
[Value and limitations of methods for measuring left ventricular mass].
M-mode echocardiographic measurement of the left ventricular mass is inaccurate when the hypertrophy is asymmetric and the ventricule very deformed. The routine calculation of the mass is based on several hypotheses, verified in normal and hypertensive subjects: the standard error (SEE) is 30-40 g, 10-15% (r > 0.9). The standard deviation of inter-examination differences (> 25 +/- 30 g with a variation coefficient c = 10-15%) makes it difficult to appreciate variations of mass in a given patient. Two-dimensional echocardiographic measurement of left ventricular mass requires the use of geometric formulae which have not been validated in the cardiomyopathies. The absence of a consensus on the models used has favorized the use of MRI and of ultrafast computed tomography. MRI measurement of mass has been validated in normal and ischaemic hearts (r > 0.97, SEE < 8 g, c = 15%) but the times of acquisition are long. Using ultrafast CT, not universally available, this measurement has been validated in vivo and in vitro, including in cardiomyopathy for which the SEE is low (6%) and reproducibility excellent (c = 4-8%), comparable with results in normal subjects.
Angiocardiography↗
[Hypertrophic cardiomyopathy: place and limitations of medical therapy].
The development of echocardiography and kindred studies have enabled the detection of an increasing number of asymptomatic forms of hypertrophic cardiomyopathy. Drug therapy, by far the commonest therapeutic method of managing this condition, has only been shown to be effective on the symptoms. Therefore, due to the risk of iatrogenic disease, medication is only proposed to symptomatic patients: high dose betablockers is the usual treatment; when ineffective or contra-indicated, verapamil may be prescribed at progressively increasing doses under strict medical control. These products may need to be given at high doses in order to be effective but excessive bradycardia may be a limiting factor. Amiodarone alone or in association, may be preferred in forms with arrhythmias. The comparative efficacy of the different drugs, especially in preventing sudden death, requires well designed, controlled, therapeutic trials. Their results, if positive, would question the dogma of only treating symptomatic patients.
Adrenergic beta-Antagonists↗
[Hormone replacement therapy in postmenopausal women and cardiovascular risk].
Although the cardiovascular effects of hormone replacement therapy of menopause have been controversial for a long time, the benefit of this treatment currently appears to be well established, despite the methodological problems of most studies and the absence of definitive demonstration by a prospective randomized study. The mechanism of this favourable action appears to be multifactorial with, in particular, an improvement of the lipid profile. In the absence of any gynaecological contraindication, the combination of a natural oestrogen and a progestogen devoid of any androgenic effect therefore appears to be the preferable treatment in postmenopausal women, especially as its cardiological value is added to other important and clearly documented actions.
Aged↗
[How to evaluate a patient with heart failure? Round table].
Evaluation of heart failure is the first step prior to introduction of an adapted therapeutic strategy. Three principal objectives must be defined: 1) identify the cause of heart failure, which may directly guide subsequent treatment (valvular heart disease, coronary artery disease, etc.); 2) evaluate the repercussions of heart failure on everyday life: evaluation of quality of life, severity of functional disorders and reduction of the everyday capacity. This evaluation is the most delicate as it is based on clinical interview: evaluation of the various NYHA stages lacks precision and reproducibility. The stress test with measurement of oxygen consumption appears to constitute an acceptable evaluation technique; 3) evaluation of the prognosis. Many studies have demonstrated precise relationships between life expectancy and a number of criteria, alteration of myocardial function, echocardiographic findings, ejection fraction, cardiac output and even an AP chest x-ray. Although statistically valid, these criteria have a limited application in individual patients. Evaluation of all these parameters is the most accurate way to predict the subsequent course of the disease which therefore allows a more accurate choice of treatment and subsequent evaluation of their efficacy.
Heart Failure↗
[Restenosis: physiopathology, treatments and prevention].
Despite fifteen years of extensive research, we still do not know how to predict or prevent restenosis. Angioplasty induces lesions in the intima, media and sometimes adventitia, resulting in a cicatricial process comprising proliferation and migration of smooth muscle cells towards the intima and secretion of extracellular matrix, leading to the formation of a neointima. Since angioplasty is associated with the simultaneous development of neointimal hyperplasia and restenosis, a cause and a effect relationship has therefore been proposed between neointimal hyperplasia and restenosis. All the restenosis prevention strategies based on inhibition of smooth muscle cell proliferation, which successfully limited restenosis in animal models have failed in man, due to the hazardous extrapolations from experimental models which are very different from the atheromatous lesions observed in man, rather than to the use of animal models in general. It is reasonable to wonder whether we have not selected the wrong target: is smooth muscle cell proliferation really responsible for restenosis? Experimental results supported by histological and ultrasonographic data in man, show that the cicatricial process which induces restenosis consists of constrictive remodelling, which decreases the perimeter of the external elastic lamina and the lumen. The use of stents appears to be the primary strategy designed to limit restenosis and prevent constrictive remodelling in man, even if it stimulates neointimal hyperplasia. Progress in the understanding of the mechanisms of postangioplasty remodelling open new perspectives in the prevention of restenosis.
Angioplasty, Balloon, Coronary↗
[Ambulatory treatment of chronic cardiac insufficiency].
Considerable progress has been made in the medical treatment of chronic heart failure. A large number of patients with NYHA class II and III heart disease can be improved to class I and II. Treatment is maintained on an outpatient basis in order to prevent episodes of acute failure, while avoiding the adverse effects of drugs at high doses or in combination. Diuretics are still the drug class most frequently prescribed, especially loop diuretics (furosemide) which have the advantage of being able to be used in patients with renal failure. Aldosterone antagonists have the pathophysiological value of reducing the development of myocardial fibrosis. Digitalis alkaloids have a positive inotropic effect, which is even observed in the presence of sinus rhythm and which is associated with slowing of the heart rate in tachyarrhythmias. Angiotensin converting enzyme inhibitors are among the most recently used drugs. They decrease the left ventricular post-load and prevent activation of the renin-angiotensin-aldosterone system. Phosphodiesterase inhibitors cannot be administered orally in the long-term and are therefore not suitable for outpatient treatment. However, they are very effective by intravenous injection during the acute phase of heart failure and cardiogenic shock in hospital.
Ambulatory Care↗
[Giant negative T waves in idiopathic apical diverticulum of the left ventricle in adults].
Left ventricular diverticula, congenital or acquired, with normal coronary arteries are rare. Apical diverticula are exceptionally rare in the adult. The authors present the clinical, paraclinical, anatomopathological pre- and postoperative data in a case of apical diverticulum of the left ventricle presenting with giant negative T waves. The differential diagnosis of these electrocardiographic changes is discussed, in particular apical cardiomyopathy, especially as the two conditions may be associated.
Adult↗
[What is left of invasive electrophysiological explorations?].
After a golden period during which invasive electrophysiological investigations improved our understanding of the physiopathology of cardiac arrhythmias the clinical indications have now become more restricted. In the investigation of syncope, electrophysiological studies are only envisaged when the diagnosis is uncertain after clinical examination, resting ECG and non-invasive investigations. Holter monitoring in particular. Three types of arrhythmia may confirm our positive diagnostic criteria: sinoatrial block in patients with a sinus node recovery time greater than 1,000 ms uninfluenced by atropine atrioventricular block in patients with distal conduction defects during sustained atrial pacing, if necessary after injection of ajmaline: ventricular tachycardia in patients sustained monomorphic VT induced by 2 or 3 extrastimuli. The selection of the clinical indications has significantly improved the diagnostic value of electrophysiological investigations. The negativity of a strictly performed protocol, even though not giving a precise diagnosis of a syncopal episode, does provide reassuring prognostic information. In VT, electrophysiological studies may also be used to evaluate the secondary prognosis but with a diagnostic value no greater than that of non-invasive investigations. Programmed ventricular stimulation is not systematic for guiding antiarrhythmic therapy in France. Reserved for recurrent VT, electrophysiological studies are of additional value in the adaptation of treatment and improve the secondary prognosis.
Arrhythmias, Cardiac↗