Biomedical subjects
F Leclercq
Publications and source records attributed to F Leclercq.
[Brugada's syndrome].
Sudden death by ventricular fibrillation is a possible complication of most cardiac diseases but there are some cases of ventricular fibrillation assumed to be idiopathic, in which the most complete aetiological investigations remain negative. Syncope and sudden death by torsades de pointe then ventricular fibrillation of long QT syndromes without cardiac disease are well known: they are purely electric abnormalities, the ionic and genetic bases of which are becoming progressively better known. In 1991, a new syndrome was described by Pedro and Joseph Brugada with particular electrocardiographic appearances (right bundle branch block with ST elevation in leads V1-V3) and episodes of ventricular fibrillation occurring in patients without apparent heart disease. This syndrome, clinically similar to the unexpected cases of sudden death during their sleep of young men from South East Asia or living there, has aroused much interest. Similarly to the congenital long QT syndrome, the concept of a purely arrhythmic abnormality seems apparent and our understanding of the sequence leading from the electrocardiographic changes to the underlying ionic abnormalities initiating them and the genetic disorders which program them, have made great strides.
Successful conservative surgery of acute ascending aortic dissection occurring during coronary angiography.
We reported the case of an acute aortic dissection complicating right guiding catheter manipulation during engagement in the right coronary ostium. Despite absence of hemodynamic deterioration, dissection progressed rapidly from the sinus of Valsalva to the ascending aorta along its entire length. At surgery, performed in emergency, the aorta was not dilated and the aortic wall did not appear pathologic. Therefore conservative surgery was performed, consisting of suture of the aortic tear and incollage of the false lumen, with good immediate and mid-term results.
[Mesothelial cyst of the adrenal gland].
We report a case of a mesothelial adrenal cyst which was incidentally discovered in a 38-year old woman. The diagnosis was confirmed by an immunohistochemistry study. Adrenal cysts are rare. They occur more commonly in female patients during the 4th and 5th decades and are usually asymptomatic. Adrenal cysts are divided into four groups : parasitic, epithelial, endothelial cysts and pseudocysts. The management is still discussed : follow-up, surgical resection or fine-needle aspiration.
[Diagnosis with hair].
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[Plurifocal testicular hamartomas and testicular feminization syndrome].
We report the case of a 14-year-old girl with a testicular feminization syndrome. The inguinal cryptorchid testis contained plurifocal hamartomas ranging from 0.5 to 1 cm. They were composed of tubules lined by cylindrical Sertoli cells immunoreactive for alpha-inhibin and p30/32(MIC2). The stroma contained few Leydig cells. Ultrastructural study showed tubules with immature Sertoli cells. The testicular feminization syndrome is caused by mutations of the androgen receptor gene. Patients with male genotype 46, XY have a female morphotype with external sexual organs without ambiguity. They have neither uterus nor ovary but two cryptorchid testis in which sex-cord stromal tumors can develop. Their malignant transformation is rare but requires preventive bilateral orchidectomy.
Malignant ventricular arrhythmias revealing anomalous origin of the left coronary artery from the pulmonary artery in two adults.
We report two cases of anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA), revealed by malignant ventricular arrhythmias in adult patients. A two coronary system was re-established in both patients, and cryotherapy was performed on one of the patients who, in addition, presented ventricular aneurysm triggering ventricular tachycardia.
Left ventricular lead insertion using a modified transseptal catheterization technique: A totally endocardial approach for permanent biventricular pacing in end-stage heart failure.
This article describes a new technique of LV lead insertion, using transseptal catheterization performed through the right internal jugular vein, to obtain a totally endocardial biventricular chronic pacing in end-stage heart failure. Three patients with QRS widening (> 180 ms) linked to complete left bundle branch block (n = 2) or right ventricular pacing (n = 1) were included in this preliminary study. Catheterization was performed under fluoroscopy and transesophageal echocardiography guidance. Transseptal catheterization was achieved by puncture of the right internal jugular vein at the base of the neck and by using a Brockenbrough needle, the tip curve of which was more curved than the standard model. A flexible long sheath was advanced in the left atrium through the interatrial septum and then a unipolar electrode was placed easily in the LV. The proximal tip of the LV lead was tunneled from the neck to the subclavian area and connected to the ventricular channel of a dual (n = 1) or simple (n = 2) chamber pacemaker. Efficient acute sensing (V wave amplitude = 13 +/- 3 m V) and pacing (acute pacing threshold = 0. 7 +/- 0.4 V) were obtained in the three patients. Early loss of capture occurred in two patients requiring lead replacement. Functional status dramatically improved in all three patients. At 6-month follow-up, biventricular pacing was maintained in all patients (mean threshold 1.4 V) who were free of clinical embolic event with oral anticoagulation therapy. This modified technique of jugular transseptal catheterization appears promising for the development of left heart pacing.
A "dysautonomic" head-up tilt test pattern in elderly patients with neurocardiogenic syncope.
The characteristics of neurocardiogenic syncope (NCS) in elderly patients remain unclear. We compared the hemodynamic profiles of young and older patients with consecutive and positive head-up tilt tests (HUT). Continuous, noninvasive, and reliable monitoring of arterial pressure (AP) and heart rate (HR) was done throughout 46 consecutive positive HUTs of symptomatic patients. The population (12-82 years old) was divided into two groups: younger patients, Y (n = 25, < or = 65 years), and older patients, O (n = 21). Changes in AP and HR after the first minute of tilting, during the stable orthostatic phase and during syncope were compared. Except for systolic pressure, baseline hemodynamic parameters were similar in Y and O. No difference appeared in the mean time elapsed before syncope (19+/-9 vs 22+/-2 min). Asymptomatic hypotension was observed, only in O, 1 minute after tilting, followed by a progressive fall in the mean AP before syncope (0+/-0.9 vs -1+/-0.7 mmHg/min) without HR increase (0.7+/-1 vs 0+/-0.6 beats/min). This pressure slope was strongly related to age (r = 0.54, P < 0.001). Hemodynamic recording during HUT identifies a dysautonomic pattern in elderly patients with NCS and the abnormal AP/HR responses to orthostasis may be a feature specific to this population. Although the central mechanism of NCS is common to all ages, the age-related characteristics of the trigger event may indicate the need for specific management at different ages.
Combined assessment of reflow and collateral blood flow by myocardial contrast echocardiography after acute reperfused myocardial infarction.
OBJECTIVE: To evaluate the combined assessment of reflow and collateral blood flow by myocardial contrast echocardiography after myocardial infarction. DESIGN: Myocardial contrast echocardiography was performed in patients with acute myocardial infarction shortly after successful coronary reperfusion (TIMI 3 patency) by direct angioplasty. Collateral flow was assessed before coronary angioplasty, and contrast reflow was evaluated 15 minutes after reperfusion. The presence of contractile reserve was assessed by low dose dobutamine echocardiography (5 to 15 micrograms/kg/min) at (mean (SD)) 3 (2) days after myocardial infarction. Recovery of segmental function (myocardial viability) was evaluated by resting echocardiography at a two month follow up. The study was prospective. PATIENTS: 35 consecutive patients referred for acute transmural myocardial infarction. RESULTS: Contrast reflow was observed in 20 patients (57%) and collateral flow in 14 (40%). Contrast reflow and collateral contrast flow were both correlated with reversible dysfunction on initial dobutamine echocardiography and at follow up (p < 0.05). The presence of reflow or collateral flow on myocardial contrast echocardiography was a highly sensitive (100%) but weakly specific (60%) indicator of segmental dysfunction recovery. Simultaneous presence of contrast reflow and collateral flow was more specific of reversible dysfunction than reflow alone (90% v 60%). CONCLUSIONS: Combined assessment of reflow and collateral blood flow enhanced the sensitivity of myocardial contrast echocardiography in predicting myocardial viability after acute, reperfused myocardial infarction. The simultaneous presence of reflow and collateral blood flow was highly specific of recovery of segmental dysfunction.
[Congenital atrioventricular block].
Congenital atrioventricular block is defined (Yater) as a documented conduction defect in a young subject with unquestionable bradycardia in the absence of a history of infection which might have caused the condition after birth. It is a rare condition (1 out of 20,000 births) and may be isolated or associated with another congenital malformation. Four cardiac malformations are classically associated: endomyocardial fibrosis, morphological abnormalities close to the conduction system: corrected transposition, left isomerism; patent ductus arteriosus and atrial septal defect apparently unrelated but the most common; the association of mitral regurgitation in adults, although the significance is not very clear. Isolated block is often observed in patients with mothers suffering from autoimmune disease, often clinically latent. Anti Ro/SS-A and La/SS-B antibodies cross into the foetal circulation and cause inflammation of the conduction tissues but the causal mechanism is not known. The diagnosis of the conduction defect is sometimes made during foetal life by echocardiography. After birth, the diagnosis is made by electrocardiography but the block is not always complete or permanent, its degree often increasing with time. In addition, in advanced degrees of block, the escape rhythm tends to slow down. Long-term follow-up studies have revised the previously considered good prognosis of isolated congenital atrioventricular block but advances in cardiac pacing provide satisfactory treatment. In the foetus, isolated atrioventricular block is usually associated with an escape rhythm > 60/min and enables normal vaginal delivery; a low heart rate < 55/min and anasarca carry a poor prognosis. In the neonate, pacing is indicated in babies with cardiac failure and a heart rate < 55/min. Follow-up by Holter monitoring, exercise testing and echocardiography is justified in children and adolescents; the patients may become symptomatic at any age. Pacing is essential in symptomatic cases (malaise, ventricular dysfunction) and useful in cases with long QT intervals, frequent ventricular extrasystoles and wide ventriculogrammes. Pacing is not always easy in children. Epicardial pacing by thoracotomy or an epigastric approach is possible but endocavitary pacing is to be preferred using thin pacing catheters introduced via the subclavian vein and small pacemakers implanted in a sub or prepectoral site. A pacing mode which restores the normal atrioventricular sequence is theoretically superior to single ventricular pacing even if rate responsive frequency.
Heart rate as a determinant of L-type Ca2+ channel activity: mechanisms and implication in force-frequency relation.
Early studies in enzymatically isolated animal cardiomyocytes indicated that voltage-gated "L-type" Ca2+ currents (ICaL) can be upregulated following an increase of the frequency of activation. Recently, we evidenced a similar regulation of ICaL in human cardiomyocytes from both left and right ventricles and atria over a physiopathological range of stimulations (between 0.5 and 5 Hz). This regulation, enhanced by the beta-adrenergic stimulation, may be involved in the frequency-dependent potentiation of cardiac contractile force in the human healthy myocardium. We show here that the frequency-dependent regulation of ICaL is controlled by the level of phosphorylation, as well as dephosphorylation, of the Ca2+ channels. It was enhanced following activation of the protein kinase A activated by intracellular cyclic AMP (cAMP). Therefore, we anticipate that all agents stimulating cAMP production will favor this process, which was demonstrated here by activating 5HT-4 receptors using serotonin. Alternatively, it was also enhanced by the phosphatase inhibitor okadaic acid which prevents Ca2+ channels dephosphorylation. Alteration or abnormal modulation by beta-adrenergic receptor stimulation of the frequency-dependent facilitation of ICaL may partly explain the altered force-frequency relation described in heart failure.
Ca2+ currents in compensated hypertrophy and heart failure.
Transmembrane voltage-gated Ca2+ channels play a central role in the development and control of heart contractility which is modulated by the concentration of free cytosolic calcium ions (Ca2+). Ca2+ channels are closed at the normal membrane resting potential of cardiac cells. During the fast upstroke of the action potential (AP), they are gated into an open state by membrane depolarisation and thereby transduce the electrical signal into a chemical signal. In addition to its contribution to the AP plateau, Ca2+ influx through L-type Ca2+ channels induces a release of Ca2+ ions from the sarcoplasmic reticulum (SR) which initiates contraction. Because of their central role in excitation-contraction (E-C) coupling, L-type Ca2+ channels are a key target to regulate inotropy [1]. The role of T-type Ca2+ channels is more obscure. In addition to a putative part in the rhythmic activity of the heart, they may be implicated at early stages of development and during pathology of contractile tissues [2]. Despite therapeutic advances improving exercise tolerance and survival, congestive heart failure (HF) remains a major problem in cardiovascular medicine. It is a highly lethal disease; half of the mortality being related to ventricular failure whereas sudden death of the other patients is unexpected [3]. Although HF has diverse aetiologies, common abnormalities include hypertrophy, contractile dysfunction and alteration of electrophysiological properties contributing to low cardiac output and sudden death. A significant prolongation of the AP duration with delayed repolarisation has been observed both during compensated hypertrophy (CH) and in end-stage HF caused by dilated cardiomyopathy (Fig. 1A) [4-8]. This lengthening can result from either an increase in inward currents or a decrease in outward currents or both. A reduction of K+ currents has been demonstrated [6,9]. Prolonged Na+/Ca2+ exchange current may also be involved [9]. In contrast, there is a large variability in the results concerning Ca2+ currents (ICa). The purpose of this paper is to review results obtained in various animal models of CH and HF with special emphasis on recent studies in human cells. We focus on: (i) the pathophysiological role of T-type Ca2+ channels, present in some animal models of hypertrophy; (ii) the density and properties of L-type Ca2+ channels and alteration of major physiological regulations of these channels by heart rate and beta-adrenergic receptor stimulation; and (iii) recent advances in the molecular biology of the L-type Ca2+ channel and future directions.
[Dobutamine echocardiography for the preoperative evaluation of patients for surgery of the abdominal aorta].
OBJECTIVE: The aim of the study was to assess the value of dobutamine echocardiography (DE) for detecting coronary artery disease (CAD) in patients scheduled for abdominal aortic surgery. STUDY DESIGN: Preliminary prospective open study. PATIENTS: Thirty-three consecutive patients due to undergo effective abdominal aortic surgery, assessed by preoperative DE. METHODS: Previous myocardial infarction and atherosclerotic risk factors (RF) were noted. Incremental doses of dobutamine were administered in order to reach 85% of age-predicted maximal heart rate. The occurrence of regional wall motion abnormalities was considered as a positive test. In this case a coronary angiography was performed. RESULTS: Four patients had a history of angina pectoris. DE was not interpretable in five patients. Among the patients without symptoms, 12 had three RF or more, 12 had less than three RF. In eight patients with a positive test, coronary angiography showed one or more significant main coronary artery stenoses. All patients with angina pectoris had a positive test. None of patients without symptoms and less than three RF had a positive test, one third of patients with no symptomatology but with three RF or more had a positive test (P < 0.05). CONCLUSION: DE has the ability to identify patients with asymptomatic CAD. DE is recommended in patients with high probability of CAD, i.e. with three RF or more.
Non-invasive assessment of inspiratory muscle performance during exercise in patients with chronic heart failure.
AIMS: The aim of this study was to assess inspiratory performance at rest and during exercise in patients with chronic heart failure in comparison with healthy controls using a non-invasive index: the tension-time index of inspiratory muscles (TTMUS). METHODS: We studied 13 patients with chronic heart failure (57 +/- 7 years) and 10 control subjects (58 +/- 6 years) at rest and during an incremental maximal exercise test. Measurements included breathing pattern (inspiratory time, total time of respiratory cycle, minute ventilation, tidal volume and respiratory frequency), mouth occlusion pressure and mean inspiratory pressure (calculated as follows: 5 x mouth occlusion pressure x inspiratory time). The maximal inspiratory pressure was measured at rest. TTMUS was calculated from the equation: TTMUS = PI/PIMAX x TI/TTOT, where PI/PIMAX is the ratio of mean inspiratory pressure to maximal inspiratory pressure and TI/TTOT is the ratio of mean inspiratory time to total time of the respiratory cycle. RESULTS: At rest, the results in patients showed non-significantly higher mouth occlusion pressure, lower maximal inspiratory pressure (P < 0.001), and a higher ratio of mean inspiratory pressure to maximal inspiratory pressure (P < 0.01). There was no difference in the breathing pattern. TTMUS was thus significantly higher in the patients with chronic heart failure (P < 0.001). At maximal exercise (77 +/- 16 W for patients with chronic heart failure vs 142 +/- 27 W for controls, P < 0.001), the ratio of mean inspiratory time to total time of respiratory cycle, the mouth occlusion pressure and the ratio of mean inspiratory pressure to maximal inspiratory pressure were not different. TTMUS was thus comparable in the two groups. During exercise, at comparable workloads (20, 40 and 60 W), the patients showed higher mouth occlusion pressure (P < 0.01) and a higher ratio of mean inspiratory pressure to maximal inspiratory pressure (P < 0.001), whereas the ratio of mean inspiratory time to total time of the respiratory cycle was similar. TTMUS was thus higher in the patients at each workload (P < 0.05). CONCLUSION: This study shows that the determination of TTMUS at rest and during exercise allows the observation of alterations in inspiratory muscle performance as a result of both reduced inspiratory strength, as measured by the maximal inspiratory pressure, and increased ventilatory drive, as reflected by the mouth occlusion pressure in patients with chronic heart failure. The non-invasiveness of this new index is an additional argument for its use in a clinical setting.
[Low-dose dobutamine echocardiographic assessment of reversible contractile dysfunction (myocardial stunning) after myocardial infarction].
Low dose (5 to 10 micrograms/min) dobutamine echocardiography was used to predict the presence of reversible contractile dysfunction (myocardial stunning) after myocardial infarction successfully revascularised in the acute phase of primary angioplasty. The investigation was undertaken in 40 patients, 4 +/- 1 days after inaugural myocardial infarction. The left ventricle was divided into 16 segments. Viable myocardium was diagnosed when the initial regional wall motion score decreased by at least 2. Resting echocardiography was performed at 2 months to evaluate the effective recovery of regional wall motion (myocardial viability). The presence of contractile reserve was documented by dobutamine echocardiography in 18 patients (45%). The sensitivity, specificity and positive and negative predictive values of dobutamine echocardiography for the diagnosis of myocardial viability were 82, 83, 78 and 86% respectively. The negative predictive value was high in all dysnergic segments (86%). The positive predictive value of the investigation was however higher in hypokinetic than in akinetic segments (73 vs 21%; p < 0.05). The recovery of regional wall motion during follow-up was statistically related to higher initial left ventricular ejection fraction (p < 0.04), the presence of angiographically documented collateral circulation before revascularisation (p = 0.007), the contractile response to dobutamine (p = 0.0001) and was observed more frequently in hypokinetic than in akinetic segments (p < 0.05). These results show that low-dose dobutamine echocardiography is a sensitive and specific investigation for predicting irreversible myocardial damage after successful primary angioplasty in acute myocardial infarction. However, even in the absence of residual coronary stenosis, the presence of viable myocardium is only identified specifically in hypokinetic segments.
[Present concepts of accessory pathways].
The possibility of ablation of arrhythmias has revived interest in accessory atrioventricular pathways. The authors propose a classification based on their electrophysiological properties, the nature of the arrhythmias which they induce, their anatomy and localisation. Classical accessory pathways have a rapid "all or nothing" type of conduction and are responsible for the WPW syndrome. They are called bundles of Kent although Kent's description does not correspond exactly to our present concept of their structures. However, some classical accessory pathways do have unidirectional conduction properties. When only retrograde reciprocating orthodromic tachycardia may occur but not preexcitation is observed in sinus rhythm: they have to be differentiated from reciprocating nodal tachycardias. Atypical accessory pathways show decremential conduction and are composed of specific tissues. When the conclusion is mainly or exclusively anterograde, tachycardias may be observed which were generally attributed to nodoventricular Mahaim fibres. When the conduction is essentially retrograde, they usually give rise to chronic junctional tachycardias.
Myocardial viability assessed by dobutamine echocardiography in acute myocardial infarction after successful primary coronary angioplasty.
Dobutamine echocardiography (5 and 10 microg/kg/ min) was performed in 40 patients 4 +/- 1 days after acute myocardial infarction reperfused by primary coronary angioplasty. The left ventricle was divided into 11 segments. Reversible myocardial dysfunction was indicated by a decrease in at least 2 grades in the total segmental score. Follow-up echocardiography was performed 2 months later. Contractile reserve was documented in 18 patients with dobutamine echocardiography (45%). Sensitivity, specificity, positive, and negative predictive value of dobutamine echocardiography in predicting improvement in contractile function at follow-up were 82%, 83%, 78%, and 86%, respectively. Negative predictive value was high in all dyssynergic segments (86%). Positive predictive value was higher in hypokinetic than in akinetic segments (73% vs 21%; p <0.05). Recovery of wall motion at follow-up was statistically associated with higher left ventricular ejection fraction (p <0.04), collateral blood flow before reperfusion (p = 0.007), and dobutamine responsiveness (p = 0.0001), and was more frequently observed in hypokinetic than in akinetic segments (p <0.05). Thus, low-dose dobutamine echocardiography accurately predicts the extent of irreversibly damaged myocardium early after successful direct coronary angioplasty in acute myocardial infarction.