[Determination of cardiac output by Doppler ultrasonics. Principle, techniques and limitations]. / Détermination du débit cardiaque par écho Doppler. Principe, techniques, limites.

The development of quantitative applications of Doppler ultrasound for the measurement of cardiac output was a lengthy and difficult process. These applications call for rigor of the part of the ultrasound cardiographer and a sufficiently echoic patient. Numerous studies have demonstrated the reliability of Doppler ultrasound in determining aortic flow. A high degree of consensus has emerged for measuring aortic areas and velocities at the ring. Doppler ultrasound quantification of the pulmonary flow has been validated in children. In adults, measurement of the pulmonary ring is often difficult and may lead to major errors in the estimation of the flow rates. The determination of mitral flow is also possible, either at the ring or at the tip of the mitral funnel. A few publications highlight the value of Doppler ultrasound in evaluation of tricuspid flow, however, these results require confirmation.

[Iatrogenic coronary stenosis after angioplasty]. / Sténoses coronaires iatrogènes après angioplastie.

Restenosis is the usual mechanism of recurrent myocardial ischaemia in the months following successful percutaneous transluminal coronary angioplasty (PTCA). Control coronary arteriography may occasionally show another cause: the constitution of a new stenosis near the dilated segment or in the left main coronary stem after angioplasty in a branch of this artery. The authors report 4 cases of patients who developed new coronary stenoses within a few weeks of PTCA, interpreted as traumatic complications of the initial procedure due to a lesion of the intima with a secondary fibrotic reaction and luminal narrowing. The guiding catheter was probably responsible for the trauma to the left main coronary stem whereas the tips of either the balloon catheter or the guide wire were thought to have been responsible for the endothelial effraction of the dilated vessels.

[Apical hypertrophic myocardiopathy with mid-ventricular obstruction and apical necrosis]. / Myocardiopathie hypertrophique apicale avec obstruction médio-ventriculaire et nécrose apicale.

In a 41-year old man hospitalized for investigation of a systolic ejection murmur, echocardiography revealed an apical (17 mm) and, chiefly, a mid ventricular (38 mm) myocardial hypertrophy resulting in a true stricture at that level. During systole the mid ventricular area became obstructed, dividing the left ventricule into an apical akinetic chamber and a proximal hyperkinetic chamber. Left ventriculography confirmed this abnormality and catheterization showed a left intraventricular pressure gradient of 60 mmHg. Although left coronary arteriography proved normal, myocardial radionuclide scanning at exercise displayed apical necrosis which resulted in a peculiar haemodynamic behaviour well demonstrated by doppler ultrasound. The apex of the left ventricle was filled in two stages: first, during atrial contraction, giving at doppler (mid ventricular sample) a positive flow with a speed of 1m/sec during 120 ms; then, during the isovolumetric period, giving a positive flow with a speed of 1m/sec during 60 ms. The apex drained during systole and protodiastole, giving a negative mid ventricular obstruction flow with a speed of 4 m/sec with protosystolic and mesodiastolic reinforcement.