Biomedical subjects

F Extramiana

Publications and source records attributed to F Extramiana.

23 records · Page 2Linked to original sources

PubMed1999

[Diagnostic value of electrocardiography using dobutamine in coronary artery disease].

OBJECTIVES: Assess the sensitivity and specificity of electrocardiograms performed during dopamine perfusion to detect coronary artery stenosis. PATIENTS AND METHODS: One hundred three coronary artery disease patients with a coronarography were studied; 23 coronarographies were normal, 59 patients were taking a beta blocker. An exercise test was also performed in 54 cases. A dobutamine perfusion was given at increasing dosage up to 50 micrograms/kg/min, in combination with intravenous atropine if needed to obtain a heart rate close to the theoretical maximum. RESULTS: The ST segment could not be analyzed reliably in 12 patients. There was an ST depression in 32 cases, an ST elevation in 20 and an isoelectric ST in 39. The sensitivity of a positive test to detect stenosis was 67% and specificity was 83%. Test sensitivity increases with increasing number of stenotic lesions. There were no false positives in patients with an ST elevation. Results were not related to gender nor beta blocker treatment. The exercise tests were globally comparable but poorer in patients taking beta blockers. There were no notable adverse effects. CONCLUSION: Dobutamine perfusion electrocardiogram is a simple well-tolerated exploration method for the diagnosis of coronary artery disease applicable in all patients. Its diagnostic value is similar to that of the exercise test and better in patients taking beta blockers. Specificity is excellent and sensitivity is acceptable, particularly in patients with mulitvessel disease.

Adrenergic beta-Agonists↗

PubMed1999

QT interval and arrhythmic risk assessment after myocardial infarction.

To assess ventricular repolarization features as predictors of ventricular tachyarrhythmias (VT) in patients with previous myocardial infarction, we performed a dynamic study of QT interval from 24-hour electrocardiographic data. QT rate dependence was enhanced in patients with VT when compared with patients without VT.

Electrocardiography↗

PubMed1999

Factors affecting epicardial dispersion of repolarization: a mapping study in the isolated porcine heart.

OBJECTIVE: Non-uniform drug-induced prolongation of repolarization predominating in the midmyocardial (M) cell layers has been shown to be responsible for perpetuation of reentry, giving rise to torsade de pointes. However, the absence of M cells in immature animals, especially the pig, suggests other possible underlying mechanisms. We sought to examine, in this species, the effects of predisposing factors to torsade de pointes on the dispersion of epicardial repolarization and their contribution to arrhythmogenesis. METHODS: Computerized mapping of repolarization and activation was conducted on the epicardial surface in 29 Langendorff-perfused hearts of eight-week-old pigs. Activation-recovery intervals were measured simultaneously from 128 unipolar electrograms. RESULTS: Baseline iso-interval maps were dipolar (41%) or multipolar (59%). Dispersion of repolarization was reverse frequency-dependent but was unaffected by lowering [K+]o. DL-Sotalol (0.1 mmol/l) reinforced local gradients and thus increased epicardial dispersion, whereas intramural recordings did not demonstrate any predominant effect in midmyocardial layers. Phenylephrine (1 mumol/l) notably augmented DL-sotalol effects. After [Mg++]o lowering, although dispersion was not significantly increased, DL-sotalol was associated with the spontaneous occurrence of polymorphic ventricular tachycardia in seven out of nine experiments. When maps of repolarization of escape beats were compared with activation maps of first arrhythmic beats, an arc of functional dissociation was observed in the vicinity of a steep gradient of repolarization in two out of nine tachycardias. CONCLUSION: Epicardial dispersion of repolarization is increased by slow rates, DL-sotalol and phenylephrine but is not the only requirement for initiation of polymorphic ventricular tachycardia. In combination with other factors, it helps continuation of the arrhythmia in this model.

Adrenergic alpha-Agonists↗

PubMed1999

Circadian modulation of QT rate dependence in healthy volunteers: gender and age differences.

QT rate dependence is known to be linked with both circadian variations of the autonomic tone and gender. However, age and heart rate variability (HRV) influences are not well established. The QT/RR relationship was evaluated, separately during the day and at night, on 24-hour electrocardiogram in 60 healthy subjects (30 men) divided into three homogeneous groups (group 1, 20-29; group 2 30-39; group 3, 40-50 years). QT rate dependence was larger during the day in both genders. Women showed stronger QT rate dependence (0.195 during the day vs. 0.154 in men P< .0001). The circadian modulation decreased with increasing age (day/night slope differences: group 1, 0.038; group 2, 0.031; group 3, 0.001; analysis of variance P<.05). In addition, QT rate dependence increased as mean RR decreased (r = -0.58, P<.0001) and decreased as HRV parameters increased. Multiple influences on QT rate dependence can be found: not only circadian and gender modulation, but also age, heart rate, and HRV interventions.

Adult↗

PubMed1998

[Contribution of doppler imaging of the myocardium to the study of cardiomyopathies].

Colour Doppler imaging (CDI) is a recent method of evaluation of cardiomyopathy based on intra-myocardial abnormalities. CDI provides quantitative assessment of myocardial wall motion both circumferential by studying the movements of the myocardium and longitudinal by studying the movements of the mitral annulus. The harmonious decrease in velocity between the endocardium and epicardium disappears in pathological conditions, showing disorganisation of wall motion within the myocardium. The decrease in the early diastolic transmural velocity gradient in patients with cardiomyopathy indicates diastolic dysfunction independent of the left ventricular systolic function. In addition, CDI is more sensitive than conventional Doppler echocardiography with grey scale because it enables earlier detection of changes induced by low-dose dobutamine, allowing distinction between trained athletes and patients with hypertrophic cardiomyopathy. The velocities of the mitral annulus help to prevent errors of interpretation of mitral blood flow as they are relatively independent on the left ventricular preload.

Cardiomegaly↗