Patrice Colin

Total arterial compliance estimated by stroke volume-to-aortic pulse pressure ratio in humans

On the basis of the windkessel model, the stroke volume-to-aortic pulse pressure ratio (SV/PP) has been proposed as an estimate of total arterial compliance, but recent studies have questioned this approximation. Aortic pressure was obtained at rest in 31 adults undergoing cardiac catheterization (47 +/- 14 yr): controls (n = 7), patients with dilated cardiomyopathy (n = 10), and patients with other cardiac diseases (n = 14). We calculated PP, mean aortic pressure (MAoP), heart period (T), SV (thermodilution cardiac output/heart rate), total peripheral resistance (R), total arterial compliance estimated by area method (Carea), and the time constant of aortic pressure decay in diastole (RCarea). In the overall population (n = 31), there was no significant difference between SV/PP and Carea. SV/PP was linearly related to Carea (SV/PP = 0.99Carea + 0.05; r = 0.98; P < 0.001); the slope and intercept did not differ from unity and zero, respectively. Similar results were obtained in the three subgroups. These results implied that PP/MAoP and T/RCarea were proportionally related (T/RCarea = 1.18PP/MAoP - 0.07; r = 0.96; P < 0.001). We conclude that for humans at rest 1) SV/PP gave a reliable estimate of Carea, and 2) T normalized by the time constant of aortic pressure decay in diastole was proportionally related to PP/MAoP. This last relationship could be considered an aspect of the coupling between the left ventricle and its load.On the basis of the windkessel model, the stroke volume-to-aortic pulse pressure ratio (SV/PP) has been proposed as an estimate of total arterial compliance, but recent studies have questioned this approximation. Aortic pressure was obtained at rest in 31 adults undergoing cardiac catheterization (47 ± 14 yr): controls ( n = 7), patients with dilated cardiomyopathy ( n = 10), and patients with other cardiac diseases ( n = 14). We calculated PP, mean aortic pressure (MAoP), heart period ( T), SV (thermodilution cardiac output/heart rate), total peripheral resistance ( R), total arterial compliance estimated by area method ( C area), and the time constant of aortic pressure decay in diastole ( RC area). In the overall population ( n = 31), there was no significant difference between SV/PP and C area. SV/PP was linearly related to C area (SV/PP = 0.99 C area + 0.05; r = 0.98; P < 0.001); the slope and intercept did not differ from unity and zero, respectively. Similar results were obtained in the three subgroups. These results implied that PP/MAoP and T/ RC areawere proportionally related ( T/ RC area= 1.18PP/MAoP - 0.07; r = 0.96; P < 0.001). We conclude that for humans at rest 1) SV/PP gave a reliable estimate of C area, and 2) T normalized by the time constant of aortic pressure decay in diastole was proportionally related to PP/MAoP. This last relationship could be considered an aspect of the coupling between the left ventricle and its load.

Myocarditis in patients with clinical presentation of myocardial infarction and normal coronary angiograms

OBJECTIVES The aim of this study was to assess the diagnosis of myocarditis in patients presenting with acute myocardial infarction (MI) and normal coronary angiograms. BACKGROUND Most often in these patients, the etiologic diagnosis remains unclear once they are found to have normal coronary arteries. The diagnosis of myocarditis mimicking MI is clinically relevant, because numerous arguments suggest a relation between myocarditis and dilated cardiomyopathy. Myocardial indium-111 (111In)-antimyosin antibody (AMA)/rest thallium-201 (201Tl) imaging allows noninvasive detection of myocarditis. METHODS Forty-five patients admitted to three intensive care units for suspicion of acute MI, with normal coronary angiograms, were investigated. Indium-111-AMA planar images and then a dual-isotope rest AMA/201Tl tomographic study were performed. Six-month echocardiographic follow-up was obtained in 80% of the patients with initial left ventricular (LV) wall motion abnormalities. RESULTS In eight patients, AMA and 201Tl scintigraphy were negative. In two patients, a matched 201Tl defect and focal AMA uptake suggested acute MI (due to prolonged vasospasm or spontaneously reperfused coronary occlusion). In 17 patients, diffuse AMA uptake over the whole LV suggested diffuse myocarditis. In 18 patients, focal AMA uptake with a normal 201Tl scan suggested diffuse but heterogeneous, or focal myocarditis. Complete functional recovery was observed in 81% of the patients with a pattern of myocarditis. CONCLUSIONS Among 45 patients presenting with acute MI and normal coronary angiograms, 38% had diffuse myocarditis and 40% had a scintigraphic pattern of heterogeneous or focal myocarditis. Short-term follow-up showed complete LV functional recovery in 81% of these patients.

The value of a completely automatic ECG gated blood pool SPECT processing method for the estimation of global systolic left ventricular function.

ObjectivesElectrocardiographically gated blood pool SPECT (GBPS) is an interesting method for measuring left ventricular (LV) ejection fraction (LVEF) and volume. Recently, the availability of completely automatic GBPS processing software has been reported. We aimed to evaluate its reliability in measuring global LV systolic function. In addition, using the same population, we compared its reliability to that of three previously reported methods for processing GBPS. MethodsWe studied the performances of the new GBPS system for the evaluation of LVEFs and volumes in 29 patients. The LVEF provided by the planar equilibrium radionuclide angiography (planarLAO) and LV volumes provided by radiological LV contrast angiography (X-rays) were used as ‘gold standards’. ResultsThe new GBPS system failed in one patient. It shows good reproducibility for the measurement of both LVEF and volume. LVEF provided by this system is moderately correlated to planarLAO (r=0.62; P<0.001). The new GBPS constantly overestimates LVEF (P<0.05). Results for LV volumes are moderately correlated to those obtained by X-ray investigation (r=0.7; P<0.001) but are significantly lower (P<0.0001). There is a linear correlation between the average and the paired absolute difference for LV volumes (r=0.52, P=0.0001). ConclusionsThe new, completely automatic, GBPS processing software is an interesting, moderately reliable method for measuring LVEF and volume. The performance of the method is lower than that previously reported for the same population for the other three GBPS processing methods.

Estimation of left ventricular performance through temporal pressure variations measured by MR velocity and acceleration mappings

To describe a method for assessing pressure variation vs. time (dp/dt) using blood flow acceleration measured by MRI, and to demonstrate its applicability in estimating left ventricular (LV) function.