Herman L. Falsetti

Left Ventricular Wall Stress Calculated from One-Plane Cineangiography

Left ventricular dimensions from routine clinical one-plane cineangiograms were combined with left ventricular pressure measurements to permit calculation of left ventricular wall stresses. The 25 patients included 12 with normal left ventricular dynamics, 6 with volume overload, 3 with outflow obstruction, and 4 with cardiomyopathy. Average stresses calculated on the basis of an ellipsoid model agreed with average values obtained from the exact solution of a thick-walled elastic ellipsoidal shell. Peak values were 150 to 625 g/cm2 in the circular direction and 75 to 365 g/cm2 in the longitudinal direction. A fiber-corrected stress was defined which represents a force per muscle fiber. The variation in fiber-corrected stress during the cardiac cycle may be considerably different from the variation in simple stress.nnThe force-velocity characteristics of circular fibers for the 25 patients are presented. The data on peak wall stress overlap in the four groups of patients. Peak velocity of circumferential fiber shortening varied from 0.44 to 0.63 lengths/sec in patients with myocardial weakness and varied from 0.74 to 2.56 lengths/sec in the other patients. Contractile element velocity was determined during ventricular ejection when the rate of force change equaled zero. Contractile element velocity of shortening was 0.22 to 0.32 lengths/sec in the cardiomyopathy group and 0.50 to 1.32 lengths/sec in the other patients.

Vmax as an Index of Contractile State in Man

The maximal, no-load, velocity for the contractile element (V max ) was estimated in 45 patients. The patients included: 17 with normal left ventricular dynamics; eight with volume overload, compensated; 11 with volume overload, decompensated; three with pressure overload; and six with cardiomyopathy. Contractile element velocity (V CE ) during isovolumic contraction was estimated in two ways: (1) from left ventricular pressure data alone, where V CE =(1/28.8p) (dp/dt), and (2) pressure data combined with measurement of left ventricular geometry (right anterior oblique cine). V max obtained in these two ways agreed well for most patients (r = 0.82). In the normal patients, V max varied from 1.46 to 2.64 muscle lengths per sec; in contrast that of the patients with cardiomyopathy varied between 0.71 and 1.34 muscle lengths per sec. Other indices of contractility (ejection fraction, peak dp/dt, peak velocity of circumferential fiber [peak V CF ], peak V CE , and V CE at zero stress) were compared on the basis of statistical correlation and consistency of other clinical evidence (presence or absence of congestive failure). Good correlation was obtained between V max and peak V SE (r = 0.68). Ejection fraction and peak V CF were less sensitive. Neither the peak rate of pressure rise or V CE at peak stress show any significant correlation with V max or clinical state. Previous studies have shown that V max can be evaluated from pressure data alone; this study confirms this finding in patients with mitral regurgitation as well as in those with normal outflow impedance.

Lipid and Carbohydrate Studies in Coronary Artery Disease

Twenty-seven patients with arteriographically proved coronary artery disease, aged 27 to 59 years, were studied for abnormalities of lipid or carbohydrate metabolism. All patients were referred because of cardiac symptoms and none had any prior history of lipid or carbohydrate abnormality. Twenty-three patients were found to have some abnormality of carbohydrate or lipid metabolism, and four had none. Seventeen patients had an abnormal lipoprotein electrophoretic pattern, 12 had elevated serum cholesterol concentrations, and 15 elevated serum triglyceride values. Eighteen patients had an abnormality of carbohydrate metabolism, 11 as determined on standard glucose tolerance tests and seven on cortisone glucose tolerance tests. These abnormalities of carbohydrate and lipid metabolism were not related to age or ponderal-index ratio. This high incidence of carbohydrate and lipid abnormalities in association with coronary artery disease may be important in the pathogenesis of the vascular disease as well as management of these patients and their progeny.

Analysis and Correction of Pressure Wave Distortion in Fluid-Filled Catheter Systems

Dynamic characteristics of a variety of catheters and their dependence on various operating parameters are presented. Careful flushing of the catheter with degassed water or saline considerably improves the performance of these systems. The operating temperature, number of catheter uses, and average transmural pressure difference do not have a significant effect.The error due to catheter distortion in commonly used left ventricular performance indices (end diastolic pressure, peak systolic pressure, maximum dp/dt and Vmax) was assessed. On the basis of these results, it is shown that the natural frequency of the catheter system must be greater than 40 Hz to produce results accurate to 10%.The experimental data were used to develop a semi-empirical model for the catheter transducer system. This model was used in the design of an analog compensator to further improve the dynamic characteristics of the catheter transducer system. The compensator requires only two parameter settings, catheter natural frequency and damping ratio.

Excision of Akinetic Left Ventricular Wall for Intractable Heart Failure

Excerpt The advent of cineventriculography has made it clear that there is a spectrum of motion disturbances involving the left ventricular wall. Akinesis, or lack of wall motion, is one serious co...

Vmax as an Index of Contractile State in Man The authors reply

The maximal, no-load, velocity for the contractile element (Vmax) was estimated in 45 patients. The patients included: 17 with normal left ventricular dynamics; eight with volume overload, compensated; 11 with volume overload, decompensated; three with pressure overload; and six with cardiomyopathy. Contractile element velocity (VCE) during isovolumic contraction was estimated in two ways: (1) from left ventricular pressure data alone, where VCE=(1/28.8p) (dp/dt), and (2) pressure data combined with measurement of left ventricular geometry (right anterior oblique cine). Vmax obtained in these two ways agreed well for most patients (r = 0.82). In the normal patients, Vmax varied from 1.46 to 2.64 muscle lengths per sec; in contrast that of the patients with cardiomyopathy varied between 0.71 and 1.34 muscle lengths per sec.Other indices of contractility (ejection fraction, peak dp/dt, peak velocity of circumferential fiber [peak VCF], peak VCE, and VCE at zero stress) were compared on the basis of statistical correlation and consistency of other clinical evidence (presence or absence of congestive failure). Good correlation was obtained between Vmax and peak VSE (r = 0.68). Ejection fraction and peak VCF were less sensitive. Neither the peak rate of pressure rise or VCE at peak stress show any significant correlation with Vmax or clinical state. Previous studies have shown that Vmax can be evaluated from pressure data alone; this study confirms this finding in patients with mitral regurgitation as well as in those with normal outflow impedance.