Assessment of left ventricular stiffness and compliance.

Invasive and non-invasive methods exist to assess left ventricular compliance (LVC). This work has two parts, one experimental and one clinical. We estimated left chamber stiffness in dogs by using volume data from radionuclide ventriculography (RNV) and left ventricular pressure data, synchronized with a gating system to the intraventricular dp/dt max to obtain volume and pressure data from a mean cardiac cycle. In five dogs after acute experimental ischaemia, the modulus chamber stiffness Kp rose from 30.2 +/- 4.4 to 55.4 +/- 5.9 (P < 0.01). In 10 dogs with experimental infarction after intra-aortic balloon pumping, Kp decreased from 33.7 +/- 5.0 to 15.5 +/- 3.9 (P < 0.01) and in five dogs with experimental infarction, after intravenous infusion of sodium nitroprusside, Kp decreased from 41.4 +/- 5.5 to 22.2 +/- 2.8 (P < 0.01). In eight normal volunteers and in 20 postmyocardial infarction patients, we estimated a parameter reflecting the LVC by using volume data with blood flow velocity at the mitral valve annulus. Assuming that the mitral flow-velocity variation reflects LV pressure changes, the formula LVC = (dv/dt)/(dp-dt) becomes (dv/dt)/(df/dt) = dv/df. Values obtained in normals were 0.841 +/- 0.295 m-1s and after myocardial infarction 0.331 +/- 0.10 m-1s. Both methods allow clear separation in groups of animals or patients according to the expected changes in LVC or stiffness.

Clinical experience with technetium-99m teboroxime scintigraphy in patients referred for myocardial perfusion evaluation.

A series of 30 patients (25 males, 5 females, age = 28-73 years) with a clinical indication of thallium-201 stress/4 hours redistribution scintigraphy has been studied using stress/rest (n = 7) or rest/stress (n = 23) protocols with technetium-99m teboroxime (CARDIOTEC, Squibb Diagnostics) in order to assess the clinical usefulness of this new molecule and to compare it to thallium. In all cases coronary artery disease was known or highly suspected, with a history of myocardial infarction in 18 cases (subacute n = 6, remote n = 12) and/or previous by-pass surgery or PTCA in 5 cases. Medical treatment was not discontinued at the time of stress testing. Coronary angiography was available for 27 patients. Exercise tests for both tracers were carried out on an ergometric bicycle during the same day and the levels of exercise achieved for the thallium studies were very similar to those achieved for teboroxime. Imaging was performed in three planar projections and sudies were evaluated using a model with 4 territories: septal and anterior assumed to correspond to the LAD artery, lateral and latero-posterior (= LCX), inferior and posterior (= RCA) and apex. Classification of results was: normal, ischemic, infarcted and infarcted with ischemia. With reference to the thallium-201 results, agreement was found in 86% (37/43) of normal regions and in 82% (63/77) of abnormal regions. Relative to documented coronary artery lesions (27 patients) sensitivity and specificity of thallium and teboroxime for exact correspondence between arteries and territories were, respectively: thallium, se = 71%, sp = 64%, teboroxime, se = 67%, sp = 75%.(ABSTRACT TRUNCATED AT 250 WORDS)