Search PubMed⌕ Search

Biomedical subjects

G Fontaine

Publications and source records attributed to G Fontaine.

At least 37 records · Page 2Linked to original sources
PubMed2000

Arrhythmogenic right ventricular dysplasia/cardiomyopathy: need for an international registry. Study Group on Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy of the Working Groups on Myocardial and Pericardial Disease and Arrhythmias of the European Society of Cardiology and of the Scientific Council on Cardiomyopathies of the World Heart Federation.

Arrhythmogenic right ventricular (RV) dysplasia/cardiomyopathy (ARVD/C) is a heart muscle disease characterized by peculiar RV involvement and electrical instability that precipitates ventricular arrhythmias and sudden death. The purpose of the present consensus report of the Study Group on ARVD/C of the Working Groups on Myocardial and Pericardial Disease and Arrhythmias of the European Society of Cardiology and of the Scientific Council on Cardiomyopathies of the World Heart Federation is to review the considerable progress in our understanding of the etiopathogenesis, morbid anatomy, and clinical presentation of ARVD/C since it first was described in 1977. The present article focuses on important but still unanswered issues, mostly regarding risk stratification, clinical outcome, and management of affected patients. Because ARVD/C is relatively uncommon and any one center may have experience with only a few patients, an international registry is being established to accumulate information and enhance the numbers of patients that can be analyzed and thus answer pending questions. The registry also will facilitate pathological, molecular, and genetics research on the causes and pathogenesis of the ARVD/C. Furthermore, availability of an international database will enhance awareness of this largely unrecognized condition among the medical community. Physicians are encouraged to enroll patients in the International Registry of ARVD/C.

Arrhythmogenic Right Ventricular Dysplasia↗
PubMed2000

Ventricular tachycardia catheter ablation in arrhythmogenic right ventricular dysplasia: a 16-year experience.

Arrhythmogenic right ventricular dysplasia (ARVD) is a structural heart disease affecting young adults that leads to cardiac rhythm disorders including supraventricular and mostly ventricular arrhythmias. Sudden death may be the first presentation of the disease. Ablation techniques have been used for the treatment of ventricular tachycardia in cases resistant to drug therapy. Radiofrequency is appropriate as a first approach for ventricular tachycardia ablation in ARVD; however, its effectiveness is less than 40% at the first session. Fulguration is effective for ventricular tachy-cardia ablation and should be used in the same session after ineffective radiofrequency ablation. However, fulguration requires expertise, general anesthesia, and more than one session in half of all patients. Radiofrequency and fulguration plus other common forms of treatment including pacemakers and automatic implantable cardioverter defibrillators provides a clinical success rate of 81% to 93% in a series of 50 consecutive patients studied during 16 years. Earlier poor reputation of fulguration was the result of poorly understood technical problems concerning the physics and biophysics of the procedure under control with presently available methods. This in-depth study of a large population over a long time period demonstrates that fulguration should be rehabilitated.

Adolescent↗
PubMed2000

Synthesis and antiviral activity of C-5 substituted beta-D- and beta-L-D4T analogues.

A series of beta-D-2',3'-didehydro-2',3'-dideoxy-nucleosides bearing a tether attached at the C-5 position and their beta-L-counterparts was synthesized. Their inhibitory activities against human immunodeficiency virus (HIV) were investigated and compared to establish relationship(s) between compound structure and their antiviral activity. No significant activity was observed for beta-D- and beta-L-modified nucleosides respectively 7a-c and 14a-c, but 7d and 14d exhibited a weak activity against HIV-1.

Anti-HIV Agents↗
PubMed2000

Low chronic pacing thresholds of steroid-eluting active-fixation ventricular pacemaker leads: a useful alternative to passive-fixation leads.

Active-fixation pacemaker leads enable pacing at various sites, have a low dislodgment rate, and are easier to extract than passive-fixation leads, though are usually not routinely implanted in the ventricle because of their higher pacing threshold. The long-term pacing threshold associated with an active-fixation steroid-eluting lead was prospectively measured in 18 women and 20 men. At a mean follow-up of 14 months (range 3-25 months), pacing threshold increased from 0.71 +/- 0.29 V to 0.96 +/- 0.28 V (P = 0.01) between implant and the first month of follow-up, then remained stable over time, consistently allowing the long-term programming of the ventricular output at 2.5 V, while lead impedance remained stable (from 647 +/- 161 omega at implant to 666 +/- 122 omega at last follow-up). If the long-term performance of this type of lead is confirmed, the routine implantation of ventricular steroid-eluting active-fixation leads should be considered since lead extraction has become a major concern.

Adult↗
PubMed2000

Arrhythmogenic right ventricular dysplasia/cardiomyopathy: need for an international registry. European Society of Cardiology and the Scientific Council on Cardiomyopathies of the World Heart Federation.

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is a heart muscle disease characterized by peculiar right ventricular involvement and electrical instability that precipitates ventricular arrhythmias and sudden death. The purpose of the present consensus report of the Study Group of the European Society of Cardiology and the Scientific Council on Cardiomyopathies of the World Heart Federation is to review the considerable progress in our understanding of the etiopathogenesis, morbid anatomy, and clinical presentation of ARVD/C since its first description in 1977. This article will focus on the important but still unanswered issues, mostly regarding risk stratification, clinical outcome, and management of affected patients. Because ARVD/C is relatively uncommon and any one center may have experience with only a few patients, an international registry is being established to accumulate information and enhance the numbers of patients that can be analyzed to answer the pending questions. The registry also will facilitate pathologic, molecular, and genetics research on the etiology and pathogenesis of the disease. Furthermore, availability of an international database will enhance awareness of this largely unrecognized condition among the medical community. Physicians are encouraged to enroll patients in the International Registry of ARVD/C.

Arrhythmias, Cardiac↗
PubMed2000

[Burst of idiopathic ventricular tachycardia complicated by arrhythmia-induced cardiomyopathy].

The authors report the case of a young man with idiopathic ventricular tachycardia occurring in bursts and arising from the pulmonary infundibulum. During follow-up, progressive, severe, dilated cardiomyopathy was observed. Radiofrequency ablation of the site of origin of this very active arrhythmia resulted in total regression of the cardiomyopathy. Contrary to generally accepted concepts, paroxystic ventricular tachycardia, usually qualified as benign, may be complicated by cardiomyopathy when the ventricular extrasystole is incessant and repetitive.

Adult↗
PubMed2000

[Etiopathogenesis of arrhythmogenic right ventricular dysplasia].

Arhythmogenic right ventricular dysplasia (ARVD) is a genetically determined cardiomyopathy with a dominant transmission mode and variable penetrance. Transdifferenciation of cardiomyocytes into adipocytes is likely to explain massive replacement of right ventricular and to a lesser extent left ventricular myocardium by adipose tissue. This phenomenon starts in the mediomural layers and extends into the epicardium. It can occur in the fetus, however youth and young adults are more frequently involved. Apoptosis defined as a programmed cell death, is likely to enhance adipogenesis and tiny fibrosis production. Inflammation can be superimposed on the genetically determined substrate and usually involves both ventricles. Myocarditis can be acute or chronic with interstitial or scar fibrosis, or active chronic. In some cases, left ventricular involvement can be as important as right ventricle, characterizing biventricular dysplasia. In Naxos disease, ARVD is associated with an ectodermic dysplasia. The transmission mode is recessive.

Adipose Tissue↗
PubMed2000

[Effect of external electrical interference on pacemakers].

Cardiac pacemaker are sensitive to many kind of electromagnetic interference (EMI). However the low rate of reported effects is due to many protective features. Risks are minimal in everyday life conditions as airport detectors, electronic anti-thief systems, domestic electrical appliances and even mobile phones with the most recent models. Interference detection can be prevented by "medically correct" setting, with the use of bipolar sensing, and ventricular sensitivity above 2 mV. The effect of EMI from the industrial world are difficult to assess and need an individual study. The most important risks occur in the medical world, with the electrocutary, thransthoracic DC shocks, and magnetic resonance imaging.

Electromagnetic Fields↗
PubMed1999

Radiofrequency catheter ablation of common atrial flutter: role of the eustachian valve.

INTRODUCTION: During radiofrequency catheter ablation of a common atrial flutter between the tricuspid annulus and the Eustachian valve "septal isthmus", double potentials were recorded along the Eustachian valve, previously described as an anatomical line of conduction block between the coronary sinus ostium and the inferior vena cava. RESULTS: Just before flutter termination, lengthening and beat to beat delay variations between the 2 components of the double potentials were correlated with simultaneous modifications of the flutter cycle length. CONCLUSION: The "septal isthmus" is a common pathway for the flutter wavefront and the impulse generating the second component of the double potential. It is also a good target for flutter ablation.

Adult↗
PubMed1999

Arrhythmogenic right ventricular dysplasia.

Arrhythmogenic right ventricular dysplasia (ARVD) is a new form of cardiomyopathy probably more frequent than commonly reported. It is a rare but important cause of sudden arrhythmic death in young, otherwise healthy persons, as well as a subtle cause of congestive heart failure. It may lead to temporary incapacitation with catastrophic consequences. Proper electrocardiographic criteria, echocardiography, nuclear medicine, or magnetic resonance imaging could identify most of these individuals. With the exception of full-thickness histological examination of the right ventricular free wall, contrast ventriculography remains the most definitive standard for a positive diagnosis. The wide clinical spectrum of arrhythmogenic right ventricular cardiomyopathies/dysplasia appears to be the result of one or possibly two factors: (a) replacement of most of the right ventricular myocardium by fat and (b) genetic susceptibility to environmental agents (myocarditis). Current treatment modalities include drug therapy, catheter or surgical ablative techniques, and modern treatments of congestive heart failure. Heart transplant is exceptional. Implantable defibrillators, used alone or in combination with drug therapy, will probably play an increasing role in ARVD and related cardiomyopathies.

Adipose Tissue↗
PubMed1999

Fat in the heart. A feature unique to the human species? Observational reflections on an unsolved problem.

Fat that is well demarcated from underlying muscle is found on the right ventricular free wall and around epicardial coronary vessels. Fat is not present in the left ventricle in normal subjects. In right ventricular dysplasia, fat and fibrosis may massively displace right ventricular myocardial tissue. It is frequently associated with some clusters of fat and fibrosis in the left ventricle. Adipocytes may be also found within fibrous tissue. In this situation it may be associated with inflammatory cellular infiltrates in both ventricles and this is called metaplastic fat. All these findings may be seen and sometimes are associated to a variable degree in the same myocardial specimen. However, fat may be interspersed with right ventricular myocardial fibres but without fibrosis or signs of inflammation. This situation is observed in more than half of the normal hearts and represents an over-looked pathologic condition only observed in the human species. The term "fat dissociation syndrome" is proposed to identify this condition. This new understanding of right ventricular myocardial structure which may be investigated by MRI may have important clinical consequences.

Adipose Tissue↗
PubMed1998

Pulse pressure response to the strain of the valsalva maneuver in humans with preserved systolic function.

Arterial pulse pressure response during the strain phase of the Valsalva maneuver has been proposed as a clinical tool for the diagnosis of left heart failure, whereas responses of subjects with preserved systolic function have been poorly documented. We studied the relationship between the aortic pulse amplitude ratio (i.e., minimum/maximum pulse pressure) during the strain phase of the Valsalva maneuver and cardiac hemodynamics at baseline in 20 adults (42 +/- 14 yr) undergoing routine right and left heart catheterization. They were normal subjects (n = 5) and patients with various forms of cardiac diseases (n = 15), and all had a left ventricular ejection fraction >/=40%. High-fidelity pressures were recorded in the right atrium and the left ventricle at baseline and at the aortic root throughout the Valsalva maneuver. Aortic pulse amplitude ratio 1) did not correlate with baseline left ventricular end-diastolic pressure, cardiac index (thermodilution), or left ventricular ejection fraction (cineangiography) and 2) was positively related to total arterial compliance (area method) (r = 0.59) and to basal mean right atrial pressure (r = 0.57) (each P < 0.01). Aortic pulse pressure responses to the strain were not related to heart rate responses during the maneuver. In subjects with preserved systolic function, the aortic pulse amplitude ratio during the strain phase of the Valsalva maneuver relates to baseline total arterial compliance and right heart filling pressures but not to left ventricular function.

Adult↗
PubMed1998

Imidazo[1,5-b]pyridazine-d4T conjugates: synthesis and anti-human immunodeficiency virus evaluation.

In an attempt to combine the human immunodeficiency virus type 1 (HIV-1)-inhibitory capacity of 2',3'-dideoxy-2',3'-didehydronucleoside analogues [nucleoside reverse transcriptase (RT) inhibitors; NRTI] and non-nucleoside RT inhibitors (NNRTI), we have designed, synthesized and evaluated for their anti-HIV activity several heterodimers of the general formula [d4T]-NH-(CH2)n-NH-[imidazo[1,5-b]pyridazine]. The synthesis of these heterodimers was conducted in three parts. The first part focused on the synthesis of the NRTI. The second part was devoted to the NNRTI and the NNRTI linked to appropriate spacers: [NNRTI]-NH-(CH2)n-NH2. In the third part, the condensation between the NRTI and the [NNRTI]-NH-(CH2)n-NH2 was performed. The in vitro inhibitory activities against HIV-1 of the [d4T]-NH-(CH2)n-NH-[imidazo[1,5-b]pyridazine] heterodimers were found to be comparable to that of d4T (stavudine) in HIV-infected cells. Moreover, the heterodimers were endowed with anti-HIV-2 activity and with anti-nevirapine-resistant HIV-1 activity. None of the heterodimers proved markedly cytotoxic to CEM-SS or MT-4 cells. There was not a clear trend toward antiviral potency on lengthening the methylene spacer in the [d4T]-NH-(CH2)n-NH-[imidazo[1,5-b]pyridazine] heterodimers.

Antiviral Agents↗