CBF reserve can be measured in humans using MCE. This method may allow the noninvasive assessment of coronary stenosis severity and the detection of microvascular dysfunction.

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Ejection phase indices such as mean velocity of circumferential fiber shortening (V-cf), ejection fraction (EF), and mean normalized systolic ejection rate (MSER) are thought to reflect the level of left ventricular (LV) inotropic state. Although known to be influenced by changes in afterload, their response to altered preload is less certain. This question was examined in ten normal subjects studied in the supine position and after 10 min of 75 degree head-up tilt. Echo VL diameter (D) and carotid pulse recordings were used to calculate LV ejection time, V-cf, MSER, LV end-diastolic and stroke volumes (EDV and SV, by D3 formula), and ejection fraction. Systemic blood pressure (BP)was measured by cuff, and heart rate (HR) counted from the ECG. Calculated LVEDV decreased with tilt (115 plus or minus 8 to 82 plus or minus 7 ml, P smaller than 0.001), as did SV (81 plus or minus 6 to 54 plus or minus 6 ml, P smaller than 0.001), and ejection time (0.31 plus or minus 0.01 to 0.27 plus or minus 0.00 sec, P smaller than 0.001), but there was no significant change in systolic or diastolic BP or HR. V-cf, EF, and MSER were not singificantly altered by tilt (1.09 plus or minsu 0.04 to 1.12 plus or minus 0.05 circ/sec; 0.70 plus or minus 0.02 to 0.65 plus or minus 0.02; and 2.29 plus or minus 0.07 to 2.43 plus or minus 0.08 end-diastolic volumes/sec, respectively). V-cf, MSER, and EF appearrelatively unaffected by acute alterations in preload. That compensatory sympathetic responses blunted potential changes cannot be excluded, although HR was not found to have increased.

Diastolic properties of the left ventricle (LV) are probably influenced by several factors, including completeness of ventricular relaxation, composition of the ventricular wall, and wall thickness. This study has utilized a combined ultrasonic and hemodynamic technique to examine the influence of LV posterior wall thickness at end diastole (h p ) on LV diastolic characteristics in 24 patients with various forms of heart disease. The slope of late diastolic LV pressure-diameter relations (ΔP/ΔD) was calculated and used as a measure of effective diastolic stiffness (S) late in diastole. S was normalized for average LV pressure during the interval of measurement (P) as S/P, called S N . LV end diastolic pressure (LVEDP), volume index (LVEDVI), and mass index (LVMI) were measured in each patient during the same study at which h p , S and S N were determined. The range of h p was 5.6 to 18.6 mm; it was highest in a patient with aortic stenosis, and lowest in those with mitral stenosis. Linear regression of h p against S, S N and LVEDP showed significant correlation, with r = 0.85, 0.75, and 0.74 respectively ( P < 0.001 for each regression analysis). Poor correlation was noted with LVEDVI, ΔP, and ΔD. Of 12 patients with LV hypertrophy (LVH) by ECG, four had normal h p (7.9 ± 1.0 mm) and eight had abnormal h p (13 ± 0.6 mm). Those with normal h p had nearly normal values for S (3.5 ± 0.5 mm Hg/mm) while those with abnormal h p showed significant increases in S (7.7 ± 1.5 mm Hg/mm), indicating that LVH may alter S only insofar as there is an associated increase in h p . Consistent with this was the observation that within the group of patients having increased LVMI, LVMI itself was a poor predictor of S ( r = 0.50, NS) while h p remained an excellent predictor of S ( r = 0.86, P < 0.001). In summary, this study suggests that wall thickness is an important determinant of left ventricular diastolic stiffness and pressure, and that wall thickness appears to predict diastolic stiffness independent of the presence or absence of LVH or increased LV mass.

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The Lillehei-Kaster (L-K) valve is a tilting disc prosthesis currently in use for heart valve replacement. We report data from phonocardiography (PHONO) and echocardiography (ECHO) in 20 patients with a normally functioning mitral valve prosthesis (MVP). The MVP is well recorded by ECHO, resembling a mitral stenosis pattern with a disc excursion of 7 to 12 mm and a mean opening and closing velocity of 37.7 and 59.8 cm/sec, respectively. Combined PHONO and ECHO show that the opening sound of the MVP is small, related to onset of valve opening and not peak opening. It follows the aortic component of the second sound (A2) by 0.05 to 0.09 sec in normals; it may be absent (12/20). Peak opening follows A2 by 0.08 to 0.12 sec. The closing sound of the MVP, best heard in the mitral area, is always two-fold with a small initial high frequency (HF) component and a second large HF sound separated by no more than 0.03 sec. The first component (A) is related to onset of closure and the second (B) to completion of closure. Systolic and diastolic murmurs were commonly present. These data establish the normal ECHO and PHONO findings for patients with L-K MVP. Two other patients are also reported in whom such data were helpful for the noninvasive evaluation of valve function, indicating in one instance acute mitral regurgitation and in the other an increase in degree of aortic regurgitation. Additional Indexing Words:Mitral valve surgery Prosthesis