A new Doppler method of assessing left ventricular ejection force in chronic congestive heart failure.

A noninvasive method using Doppler echocardiography was developed to determine the force exerted by the left ventricle in accelerating the blood into the aorta. The value of this new Doppler ejection index in the assessment of left ventricular (LV) performance was tested in 36 patients with chronic congestive heart disease undergoing cardiac catheterization and in 11 age-matched normal control subjects. The 36 patients were subgrouped into 3 groups based on angiographic ejection fraction (LV ejection fraction greater than 60, 41 to 60 and less than or equal to 40%). According to Newton's second law of motion (force = mass X acceleration), the LV ejection force was derived from the product of the mass of blood ejected during the acceleration time with the mean acceleration undergone during that time. In patients with LV ejection fraction less than or equal to 40%, LV ejection force, peak aortic velocity and mean acceleration were severely depressed when compared with the other groups (p less than 0.001). In patients with LV ejection fraction of 41 to 60%, LV ejection force was significantly reduced (22 +/- 3 kdynes) when compared with normal subjects (29 +/- 5 kdynes, p = 0.002) and with patients with LV ejection fraction greater than 60% (29 +/- 7 kdynes, p = 0.009); peak velocity and mean acceleration did not differ between these 3 groups. The LV ejection force showed a good linear correlation with LV ejection fraction (r = 0.86) and a better power fit (r = 0.91). Peak aortic blood velocity and mean acceleration showed less good linear correlations with LV ejection fraction (r = 0.73 and r = 0.66, respectively). The mass of blood ejected during the acceleration time also showed a weak linear correlation with LV ejection fraction (r = 0.64). An LV ejection force less than 20 kdynes was associated with a depressed LV performance (LV ejection fraction less than 50%) with 91% sensitivity and 90% specificity. Thus, these findings suggest that LV ejection force is a new Doppler ejection phase index that appears to be more accurate than peak aortic blood velocity and mean acceleration for the assessment of systolic LV function.

A simplified normalized ejection phase index measured by Doppler echocardiography for the assessment of left ventricular performance.

Although useful for the assessment of directional changes in contractility in individual patients, resting peak aortic blood velocity is of limited value for differentiating among patients with different levels of basal cardiac function. A dimensional analysis based on fluid dynamics shows that peak aortic blood velocity is not only generated by the contracting myocardium but also reflects the convective acceleration of blood from the left ventricle to the aorta. The reduction of cross-sectional area from the midleft ventricle to the aorta at the time of peak aortic blood velocity generates the convective acceleration. Accordingly, a higher convective acceleration due to left ventricular (LV) enlargement as observed in cardiomyopathy may explain why peak aortic blood velocity can be maintained as normal although myocardial contractility is depressed. This study tested the hypothesis that peak aortic blood velocity normalized by the ratio of midleft ventricle to aortic cross-sectional areas might provide a reliable index of LV performance. Nine normal control subjects and 25 patients undergoing catheterization were studied by M-mode, 2-dimensional and Doppler echocardiography. The normalized peak velocity measured noninvasively showed a high correlation with angiographic ejection fraction (r = 0.90, p less than 0.0001). Peak aortic blood velocity and the ratio of midleft ventricle to aortic cross-sectional areas alone correlated less well with ejection fraction (r = 0.76 and r = 0.75, p less than 0.0001, respectively). Furthermore, peak aortic blood velocity showed a significant overlap between patients with normal and those with abnormal LV function, whereas normalized peak aortic blood velocity was a better discriminator.(ABSTRACT TRUNCATED AT 250 WORDS)

[Value and limitations of pulsed Doppler echocardiography in the determination of pressure gradients in children]. / Intérêt et limites de l'échocardiographie Doppler pulsé pour la détermination des gradients de pression chez l'enfant.

The aim of this study was to evaluate the results of pulsed Doppler echocardiography in assessing pressure gradients in children despite the theoretical limitations of this technique in the measurement of high velocity blood flow (due mainly to the phenomenon of "aliasing"). 20 patients with an average age of 6.7 years (range 3 months to 19 years) were studied by 2D echocardiography and pulsed Doppler within 48 hours of cardiac catheterisation. Valvular stenosis was present in 14 cases (aortic, 7, pulmonary, 7). There were 3 cases of infundibular obstruction and 2 vascular stenosis (coarctation of the aorta and stenosis of a branch of the pulmonary artery). One patient had stenosis at the origin of a prosthetic tube graft. The gradient was estimated from the Doppler flow curves using simplified Bernoulli formula (P = 4 X maximal jet velocity). In 17 patients (gradients of 20 to 90 mmHg) an excellent correlation was observed between the pulsed Doppler and haemodynamic results (r = 0.90). In 3 cases with gradients over 80 mmHg it was not possible to quantify the gradient but pulsed Doppler fixed an inferior limit of 80 mmHg. Therefore, using a 3 or 2.25 MHz probe at the low depths of investigation encountered in childhood, pulsed Doppler gave a reliable indication of pressure gradients less than or equal to 80 mmHg. These results and the non-invasive nature of the method make pulsed Doppler a particularly interesting complementary examination in children or babies with stenotic cardiac lesions.

[Transesophageal electrophysiological study in non sedated children younger than 11 years with a Wolff-Parkinson-White syndrome]. / Etude électrophysiologique par voie transoesophagienne chez des enfants de moins de 11 ans, non sédatés, ayant un syndrome de Wolff-Parkinson-White.

UNLABELLED: The electrophysiological evaluation of Wolff-Parkinson-White syndrome (WPW) is recommended in children aged more than five years to detect a risk of life-threatening arrhythmia. The purposes of the study were to determine the feasibility of transesophageal EPS in a child between six and 10 years in out-patient clinic. METHODS: Electrophysiological study (EPS) was indicated in 22 children, aged six to 10 years, with a manifest WPW either for no documented tachycardia (n=7), unexplained dizziness (n=2) or for a sportive authorization in 10 asymptomatic children. Two of the last children had a history of permanent tachycardia after the birth but were asymptomatic since the age of one year without drugs. RESULTS: EPS was performed in all children. The main difficulty lied in passing the catheter through the mouth. Programmed stimulation at cycle length of 380 ms was performed in all children to avoid high rates of pacing when the conduction through the accessory pathway (AP) and normal AV system was evaluated. Isoproterenol was not required in five children, because they developed a catecholaminergic sinus tachycardia. The AP refractory period was determined in all children between 200 and 270 ms. Orthodromic reentrant tachycardia (RT) was induced in 11 children, three asymptomatic children (27%), seven complaining of tachycardia and one with syncope. Rapid antidromic tachycardia was induced in this last child with dizziness. Atrial fibrillation was never induced. CONCLUSIONS: Esophageal EPS can be performed without sedation in a young child six to 10-year-old with a shortened protocol of stimulation, which was capable to clearly evaluate the WPW-related risks.

[Williams-Beuren facies with mental retardation and tetralogy of Fallot]. / Faciès de Williams-Beuren avec retard mental et tétralogie de Fallot.

The "elfin facies", described by Williams and Beuren, is usually associated, beside mental retardation, with a supravalvular aortic stenosis and, more broadly, with multiple arterial stenoses. Other types of cardiac defects were described in this context, but the case reported by the authors is the first one with a tetralogy of Fallot. The hypothesis of widerspread histodysplastic lesions is discussed: the process may be early enough to alter the morphogenesis of the cardiac conus and to produce, more lately, the classical stenotic lesions of the arterial wall.

[Evaluation of the pulmonary artery and its branches by two-dimensional echocardiography in the tetralogy of Fallot and pulmonary atresia in infants. Angiocardiographic correlation and therapeutic implications]. / Evaluation de l'artère pulmonaire et de ses branches en échocardiographie bidimensionnelle dans la tétralogie de Fallot et l'atrésie pulmonaire chez le nourrisson. Corrélation angiocardiographique et implication thérapeutique.

Twenty-two infants aged 5 days to one year (mean: 3.8 months), consisting of 17 with tetralogy of Fallot and 5 with pulmonary atresia-ventricular septal defect, were prospectively investigated by two dimensional echocardiography (2 D echo) in order to evaluate the severity of the impairment of the pulmonary outflow tract and value of 2 D echo in the preoperative evaluation. Right pulmonary artery (PA), observed by angiography in 20 patients, was correctly recorded and could be measured in all cases (20/20), whereas the left PA was seen in 19 patients (19/20). Pulmonary confluence was recognized in 20/20 cases and its absence in 2 cases. In one patient without pulmonary confluence, a large substituted systemic vessel was mistaken for right PA. Echo established in the 22 patients (100%) the presence (17 cases) or absence (5 cases) of continuity between the right ventricle and the PA. Echo demonstrated 2 out of the 3 stenoses of the branches found by angiography. The internal diameter of PA measured by echo, ranging from 3 to 9 mm, was compared with angiographic measurements. A significant linear correlation was observed for each diameter (ring, trunk and branches) between the two techniques. However, echo slightly under-estimated the angiographic diameters. These results show that 2 D echo is a reliable method to determine the severity of impairment of the pulmonary outflow tract in infants with tetralogy of Fallot. They suggest that is may be used to guide the choice of surgical procedure and is adequate, in selected patients, to carry out a palliative intervention without open surgical procedure.

Loss of efficacy of flecainide in the Wolff-Parkinson-White syndrome after isoproterenol administration.

Although anterograde conduction through a Kent bundle with a short refractory period was suppressed by 300 mg of flecainide acetate, the infusion of small amounts of isoproterenol caused the reappearance of WPW and permitted the induction of an atrial tachycardia with 1/1 conduction through the accessory pathway at a rate of 260 beats min-1. This case shows that the effect of isoproterenol may be maintained after apparently successful flecainide therapy.