Cardiovascular research
-
Cardiovascular research · Apr 1998
Differential uptake of myocardial perfusion radiotracers in normal, infarcted, and acutely ischemic peri-infarction myocardium.
We measured the uptake of technetium-99m tetrofosmin (99m Tc) and thallium-201 (201 TI) in areas of healed transmural myocardial infarction and in the regions of acute peri-infarction ischemia. ⋯ A 1-month old infarct scar with no viable myocardial tissue can take up significant fractions of 99mTc-tetrofosmin and 201Tl even in the absence of coronary collateral perfusion. Data suggest that the infarct scar can extract these radiotracers from the intraventricular blood.
-
Cardiovascular research · Apr 1998
Inotropic response of stunned hypertrophied myocardium: responsiveness of hypertrophied and normal postischemic isolated rat hearts to calcium and dopamine stimulation.
Severely hypertrophied myocardium was described to have a reduced tolerance towards ischemia. For non-hypertrophied hearts inconclusive findings on the Ca(2+)-responsiveness are reported. Information sensitivity to reversible ischemia and on postischemic Ca(2+)-responsiveness of hearts with clinically common moderate hypertrophy is lacking. Thus, the responsiveness of hypertrophied and normal postischemic myocardium to positive inotropic stimulation should be investigated in the present study. ⋯ The findings demonstrate that after moderate reversible ischemia the steady-state function is similarly decreased in hypertrophied and non-hypertrophied postischemic myocardium. The maximum response to Ca2+ is significantly reduced in both types of myocardium, while the Ca2+ sensitivity is unchanged. Identical results after maximum dopamine stimulation as after Ca2+ indicate that the releasibility of Ca2+ and the beta-adrenoceptors are not the critical causes for the postischemic dysfunction in hypertrophied or non-hypertrophied myocardium.
-
Cardiovascular research · Apr 1998
Evidence for an influence of mechanical restitution on beat-to-beat variations in haemodynamics during chronic atrial fibrillation in patients.
We tested the hypothesis that beat-to-beat changes in haemodynamics during atrial fibrillation include an effect of each preceding R-R interval through the interval-strength relationship (mechanical restitution). ⋯ Mechanical restitution, which causes beat-to-beat changes in inotropic state, accounts in part for the changes in stroke volume in atrial fibrillation.