SUMMARY Cardiac output determined by Doppler echocardiography was compared with that determined by thermodilution at rest and during dobutamine infusion in 10 patients (group A) and by the Fick method at rest in 11 patients (group B). All patients had angina pectoris without valvular heart disease. Maximum spatial blood velocity and cross sectional aortic area were estimated by the Doppler technique and echocardiography. Cardiac output was calculated by multiplying blood velocity by aortic area at various levels in the ascending aorta. The best correlation of cardiac output between the invasive and non-invasive methods was obtained when maximum velocity in the aortic root and the aortic orifice area were used in the calculations. Cardiac output was considerably overestimated when area measurements in the aortic root were used.The Doppler technique for measuring blood velocities in the human aorta was first reported by Light.' Later several investigators attempted to estimate cardiac output by multiplying the velocity by the cross sectional area of the aorta,2-4 but the results have been confficting.5-7 One important factor is that there is no general agreement on where in the aorta the area or the blood velocity should be measured. The present investigation was, therefore, designed to elucidate this problem by comparing the results of the non-invasive method with those of two generally accepted invasive methods-thermodilution and the Fick method.
Patients and methods
STUDY POPULATIONTwenty one patients (18 men, three women, mean age 53 (range 41-64) years with angina pectoris who were
A double-blind study has been performed in patients with aortic ball valves in order to study the antithrombotic effects of one gm of acetyl-salicylic acid (ASA) daily combined with anticoagulants, as compared with that of anticoagulants alone. The combined treatment offered a significantly better protection, the incidence in the two groups being 1.8 and 9·3 arterial thromboembolic complications per 100 patients per year, respectively. Encouraged by these results, a pilot study on the effects of ASA alone was started in 77 patients from both groupa of the first study. They all received one gm of ASA daily, then the dose of anticoagulants was reduced gradually and the drug discontinued on average five weeks later. Six arterial thromboembolic episodes occurred in five patients during the following five months, the incidence being 14.5 complications per 100 patients per year. The study was therefore ended, and anticoagulant therapy re-instituted in addition to ASA. The results indicate that combined treatment with ASA and anticoagulants more effectively inhibits arterial thrombus formation than does each of the drugs alone.
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