The effects of developing perinephritic hypertension (2-3 weeks) and a more stable period of perinephritic hypertension (-14 weeks) were examined on indexes of left ventricular (LV) diastolic function in conscious, chronically instrumented dogs. The complete period of diastole was studied using indexes of isovolumic relaxation (T-), early filling (LV +dD/dt), and stiffness (myocardial stiffness and chamber stress/diameter ratio). During developing hypertension, increased LV end-diastolic pressure, LV end-diastolic stress, peak filling rate, myocardial stiffness, and the stress/diameter ratio increased (p<0.05); the time constant x was not changed. These changes were associated with preserved baseline levels of coronary blood flow (radioactive microspheres) but an impaired coronary vasodilator response to adenosine. Acute administration of phenylephrine in the normotensive dogs caused increases in systolic and diastolic stress and resulted in increases in myocardial stiffness and in the stress/diameter ratio similar to values observed in developing hypertension. During stable hypertension, LV end-diastolic stress, peak filling rate, and both parameters of late-diastolic function (myocardial stiffness and stress/diameter ratio) returned toward control values, but the isovolumic relaxation time constant was increased. Quantitative histological evaluation revealed no increase in stainable connective tissue in dogs with stable hypertension compared with control dogs, and hydroxyproline concentration was not increased in the subendomyocardium, midmyocardium, or subepimyocardium of the dogs with chronic perinephritic hypertension. Thus, in developing hypertension, major alterations in diastolic function were observed that were not structurally related, since these changes 1) could be induced in normal dogs by increasing preload and afterload acutely with phenylephrine and 2) were improved during the ensuing stable period of hypertension. (Circulation Research 1991;68:555-567) In recent years, there has been increasing interest in diastolic properties of the heart during the development of systemic hypertension.1-3 Using a renovascular model of hypertension in rats, Capasso et a14 found a decrease in the velocity of relaxation in a papillary muscle preparation. Using isolated perfused hypertensive rat hearts, Alfaro et a15 found an impairment in negative left ventricular (LV) dP/dt. Several reports1'6 in humans studied by both echocardiographic and radionuclide techniques support the notion of impaired diastolic relaxation in ventricles with systolic

Computed tomography is the method of choice for initial evaluation of patients with potential suprasellar masses. In our experience, CT has proved completely reliable for detecting or ruling out the presence of a suprasellar mass, the direction and degree of parasellar extension, and the presence of any calcific or cystic component of the lesion. When multiple cut CT has been negative, further diagnostic studies have proved unrewarding. When CT has been positive, additional studies have been required in some cases to rule out aneurysm prior to craniotomy.

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Three extra-axial posterior fossa epidermoid tumors manifested nearly identical CT appearance of large size, sharp margination, apparently homogeneously increased attenuation in the range of 80-120 Hounsfield units, and absence of contrast-agent enhancement. This constellation of findings is distinctly different from that reported previously, and appears to be characteristic for some epidermoid tumors.