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T Aversano

Publications and source records attributed to T Aversano.

22 records · Page 2Linked to original sources
PubMed1986

End-systolic measures of regional ventricular performance.

Dimension change measures of regional ventricular function, such as absolute or percent wall thickening (delta T or % delta T) or segmental shortening (delta L or % delta L), are highly load dependent. In 16 anesthetized mongrel dogs we assessed use of the end-systolic pressure-thickness and end-systolic pressure-length relationships (ESPTR, ESPLR) as more load-independent measures of regional function. We found that the ESPTR and ESPLR could be measured without detectable baroreceptor-mediated reflex changes in cardiac contractile state. Systemic administration of dobutamine shifted the ESPTR to the right and the ESPLR to the left of control, mainly due to a change in the slope (Ees) of the relationships. Both delta T, % delta T and delta L, % delta L failed to detect the positive inotropic effect of dobutamine because of an associated reduction in preload. With systemic administration of propranolol, ESPTR, ESPLR, delta T, % delta T, and delta L, % delta L detected the negative inotropic effect. Thus systemic propranolol shifted the ESPTR to the left and the ESPLR to the right of control, mainly due to a change in Ees. Regional administration of dobutamine shifted the ESPTR and the ESPLR in the direction of positive contractility in the region receiving the drug, whereas simple dimension change measures of regional function failed to detect the inotropic effect because preload fell and the timing of regional end-systole was altered. With regional propranolol both the ESPTR, ESPLR and simple dimension change measures detected the negative inotropic effect. Thus the ESPTR, ESPLR is a reliable measure of regional ventricular function and may be better than simple dimension change measures of regional function, particularly when loading conditions or the timing of regional systole is altered by an intervention.

Animals↗
PubMed1985

Persistence of coronary vasodilator reserve despite functionally significant flow reduction.

This study was done to determine whether coronary vasodilator reserve is exhausted when coronary flow falls and regional function becomes abnormal during low-pressure perfusion. In 10 open-chest, anesthetized dogs the left circumflex coronary artery (LC) was cannulated and perfused via a blood-filled reservoir. At LC pressures of 35 and 50 mmHg, regional segment lengths were measured with sonomicrometer crystals and regional flow with radiolabeled microspheres before and after adenosine vasodilation. Control measurements were made at 80 mmHg perfusion pressure. Prior to adenosine, flow fell transmurally when LC pressure was reduced to 50 and 35 mmHg and rose significantly following adenosine. No change in function occurred at an LC pressure of 50 mmHg, but at 35 mmHg LC segmental shortening fell to 30 +/- 14% of control, and LC flow fell to 42 +/- 5% of control, with endocardial and epicardial flows of 0.40 +/- 0.04 and 0.70 +/- 0.09 ml . min-1 . g-1, respectively. After adenosine, endocardial and epicardial LC flow rose to 0.69 +/- 0.08 and 1.81 +/- 0.47 ml . min-1 . g-1, respectively (P less than 0.05). LC segment shortening improved modestly to 50 +/- 15% of control (P less than 0.02). We conclude that transmural vasodilator reserve is maintained in the face of functionally significant reductions of coronary flow at low perfusion pressure. Adenosine-induced flow increases are associated with a modest improvement in segmental function.

Adenosine↗
PubMed1984

Preload-induced alterations in capacitance-free diastolic pressure-flow relationship.

We have studied the influence of left ventricular diastolic pressure (LVDP) on diastolic coronary pressure-flow relationships independently of effects of capacitive flow in an open-chest heart-blocked canine preparation in which the left circumflex (LC) bed was vasodilated with adenosine and perfused with a programmable servo valve pressure source. At the onset of long diastoles produced by cessation of ventricular pacing, LVDP was adjusted to, and maintained at, a preselected level using a blood-filled reservoir. Right atrial pressure was kept constant at approximately 8 mmHg. LC pressure (PLC) was then made to decline and rise sequentially at a constant rate (2-40 mmHg/s), with LC inflow reaching zero at the nadir of the declining pressure ramp. The capacitance-free diastolic pressure-flow relationship was considered to lie midway between the instantaneous relationships derived from each down and up ramp pair. All capacitance-free relationships were curvilinear, and the degree of curvilinearity was accentuated with increasing preload. Pressure-axis intercepts (Pf = 0) increased from 14 +/- 1.1 (SE) to 23 +/- 1.4 mmHg as preload was raised from 6-10 to 31-35 mmHg. Coronary conductance, taken as the slope of the pressure-flow relationship at any given PLC, fell progressively as preload rose, with the fall being more marked at higher levels of preload and lower values of PLC. Diastolic coronary flow also decreased as a function of preload, reflecting the increases in Pf = 0 and decreases in conductance.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗