Michel Dahan

Prevalence and significance of left ventricular filling abnormalities determined by Doppler echocardiography in young type I (insulin-dependent) diabetic patients

In 16 insulin-dependent diabetic patients, 36 +/- 8 years old with no microangiopathy, hypertension or coronary artery disease, and 16 healthy control subjects matched for sex, age and body surface area, the following parameters were obtained by Doppler-echocardiography: (1) end-diastolic left ventricular thickness and radius; (2) aortic pulse wave velocity; (3) mitral flow with measurement of early and late (atrial) peak velocities (E and A), pressure half-time and the velocity time integrals of the entire mitral curve and of the atrial wave; and (4) isovolumic relaxation time (i.e., the time between aortic closure and the mitral opening signals recorded simultaneously by continuous-wave Doppler). Heart rate and systolic blood pressure were not different in the 2 groups. Aortic pulse wave velocity and the wall thickness to radius ratio were significantly increased in the diabetic patients compared to the controls. E was significantly reduced whereas A/E, pressure half-time, the atrial contribution to the left ventricular filling (i.e., the ratio of the atrial velocity time integral to the mitral velocity time integral) and the isovolumic relaxation time were significantly increased in the diabetic group versus the control subjects. Lastly, 11 of 16 diabetic patients (69%) had at least 2 of the following abnormalities: A/E greater than 0.71, an atrial contribution to the left ventricular filling greater than 0.25, a pressure half-time greater than 50 ms and an isovolumic relaxation time greater than 88 ms. No correlations were found between the wall thickness to radius ratio, aortic pulse wave velocity and the filling indexes.(ABSTRACT TRUNCATED AT 250 WORDS)

Determinants of stroke volume response to exercise in patients with mitral stenosis: A doppler echocardiographic study

OBJECTIVESnThe aim of this study was to assess exercise-induced changes in stroke volume and their main determinants in mitral stenosis.nnnBACKGROUNDnThe mechanisms of the stroke volume response to exercise in mitral stenosis are not clearly established.nnnMETHODSnTwenty-seven patients with mitral stenosis, aged 47 +/- 13 years, and 10 healthy control subjects, aged 46 +/- 11 years, were examined by Doppler echocardiography to obtain stroke volume, mitral velocity-time integral and calculated mitral valve area (by continuity equation) at rest and during submaximal supine bicycle exercise. Measured mitral valve area at rest and total mitral score were also obtained.nnnRESULTSnDuring exercise, stroke volume increased significantly (p < 0.001) in the control subjects (+25 +/- 6%) but remained unchanged in the patients. In 10 patients (Group I), stroke volume increased by > or = 14% (+23 +/- 10%, p < 0.001); in the other 17 (Group II), it decreased or increased by < 14% (-5 +/- 14%, p = NS). Mitral velocity-time integral did not change in the three groups, whereas calculated mitral valve area increased significantly (p < 0.001) and similarly in Group I and the control group but remained unchanged in Group II. The exercise change in calculated mitral valve area correlated significantly with both measured mitral valve area at rest (r = 0.46, p < 0.05) and total mitral score (r - 0.53, p < 0.005). However, at constant mitral score, exercise change in calculated mitral valve area no longer correlated significantly with measured mitral valve area at rest.nnnCONCLUSIONSnIn mitral stenosis, the change in stroke volume during exercise depends on the change in mitral valve area, which itself depends on the degree of mitral valve damage.

Relationship between left ventricular hypertrophy, myocardial contractility, and load conditions in hemodialysis patients: An echocardiographic study

Left ventricular hypertrophy (LVH) is common and is an independent cardiac risk factor in dialysis patients. The aim of this study was to assess hemodynamic determinants of LVH and, more particularly, the relationship between left ventricular mass, myocardial contractility, and load conditions. Eighty dialysis patients aged 51 +/- 15 years were prospectively studied by echocardiography. LVH was detected in 62 patients (78%). Left ventricular mass was significantly correlated to both end-diastolic volume (r = 0.54; P < 0.001) and end-systolic stress/end-systolic volume, an index of contractility (r = -0.66; P < 0.001), but not to systolic blood pressure or end-systolic stress, both indexes of afterload. Thus, in dialysis patients, the degree of LVH is significantly correlated with the severity of both left ventricular dilatation and contractile myocardial failure, but not with left ventricular afterload.

Hemodynamic action of nicorandil in chronic congestive heart failure

Nicorandil is a new compound that has shown potent vasodilator activities on venous and arterial beds in experimental pharmacology. This study was designed to evaluate the magnitude and the time course of hemodynamic effects of different doses of nicorandil in congestive heart failure. Eleven patients with severe congestive heart failure (New York Heart Association class III or IV), with a cardiac index less than 3 liters/min/m2 and a pulmonary wedge pressure greater than 15 mm Hg were enrolled in the study. Three patients had ischemic dilated cardiomyopathy and 8 had idiopathic dilated cardiomyopathy. Hemodynamic assessments were performed by right-sided cardiac catheterization (Swan-Ganz catheter) with cardiac output determination (thermodilution) at baseline and from 30 minutes to 12 hours after single oral administration of nicorandil; 3 patients were given 40 mg, 6 patients 60 mg, and 2 patients 80 mg. Maximal hemodynamic changes were observed 30 minutes after dosing and remained statistically significant at 3 hours. Thirty minutes after drug administration, pulmonary wedge pressure decreased 34 +/- 6%, cardiac index increased by 55 +/- 13% and diastolic and mean arterial pressures decreased by 15 +/- 3% and 9 +/- 2%, respectively, from baseline values. The decrease in systolic blood pressure was slight (5 +/- 2%) and not statistically significant. Calculated systemic vascular resistances decreased by 36 +/- 6% and heart rate did not significantly change. Nicorandil was well tolerated. Thus, the results of this first study of nicorandil in congestive heart failure demonstrated the unloading action of this compound on the failing heart, leading to an improvement in cardiac function; further investigation of nicorandil in this therapeutic area is needed.

Influence of preload reserve on stroke volume response to exercise in patients with left ventricular systolic dysfunction : A Doppler echocardiographic study

OBJECTIVESnThis study evaluated the role of preload reserve in the stroke volume response to exercise in patients with left ventricular systolic dysfunction by assessing the relation between stroke volume and late left ventricular diastolic filling during exercise.nnnBACKGROUNDnIn patients with left ventricular diastolic dysfunction, the absence of left ventricular distension is the fundamental mechanism explaining the nonaugmentation of stroke volume during exercise.nnnMETHODSnIn 32 patients with left ventricular systolic dysfunction and 16 healthy control subjects, mitral and aortic velocities were recorded by Doppler echocardiography at rest and during submaximal supine bicycle exercise. Stroke volume, peak early (E) and late (A) mitral velocities, A/E ratio and end-diastolic filling were measured at rest and during exercise.nnnRESULTSnStroke volume increased significantly in control subjects but did not change in patients. Peak early mitral velocity increased significantly and to the same extent in both groups, whereas peak late mitral velocity and end-diastolic filling increased significantly in both groups but more so in control subjects; the A/E ratio increased significantly in control subjects but did not change in patients. In addition, stroke volume correlated significantly with peak late mitral velocity during exercise in patients (r = 0.72, p < 0.001).nnnCONCLUSIONSnCompared with control subjects, patients with left ventricular systolic dysfunction exhibited limited increases in both stroke volume and late left ventricular filling during exercise. Furthermore, their stroke volume response correlated with the capacity of the left ventricle to increase late diastolic filling, that is, preload reserve.

Tolérance à l'effort maximal après transplantation cardiaque*

Resume La transplantation cardiaque a transforme le pronostic des insuffisants cardiaques. Toutefois, les premieres etudes realisees chez des patients apres greffe cardiaque avaient montre une reduction persistante de la tolerance a leffort apres greffe cardiaque chez des patients devenus totalement asymptomatiques. Pour confirmer cette observation et essayer den comprendre les mecanismes, une evaluation cardiorespiratoire a lexercice a ete realisee chez 14 transplantes cardiaques 8 ± 8 mois apres lintervention. LaVO 2 max est a 17,9 ± 3,7 ml/min/kg, significativement plus basse que celle dun groupe controle dhypertendus moderes apparies pour lâge et non statistiquement differente que celle dun groupe dinsuffisants cardiaques en classe fonctionnelle III de la NYHA, de meme âge, adresse pour bilan pregreffe. Dix patients ont ete etudies sequentiellement (9 ± 8 mois et 20 ± 12 mois apres lintervention); dans cet intervalle de temps, leur consommation maximale doxygene a faiblement augmente (de 18,1 ± 2,9 a 19,8 ± 2,7 ml/min/kg) (NS). Ainsi, avec un recul de pres de 1 an, en labsence de tout rejet, lamelioration de laptitude fonctionnelle a ete moderee, restant toujours a la limite inferieure de ce qui est considere comme une aptitude fonctionnelle normale. Les mecanismes possiblement a lorigine de cette alteration residuelle de la tolerance a lexercice sont multiples. La denervation cardiaque aboutit a une reduction de la reserve chronotrope qui semble etre le mecanisme essentiel; une reinnervation progressive avec le temps, au moins fonctionnelle, permet une augmentation moderee et tres incomplete de cette reserve chronotrope avec le temps. Une dysfonction diastolique est frequente de mecanisme non univoque. Si le fait que la reserve contractile a leffort est reduite et discutee, il est clair que lhypertension arterielle est un facteur deletere. Enfin, une hyperstimulation neurohormonale partielle, non corrigee par lintervention, et surtout des anomalies musculaires liees au deconditionnement et/ou au traitement corticoide alterent grandement la tolerance a lexercice qui, en labsence de reentrainement, represente environ 50% des valeurs normales.