Effect of olprinone, a phosphodiesterase III inhibitor, on arterial wall distensibility: differentiation between aorta and common carotid artery

The association of rate pressure product (RPP) and myocardial perfusion imaging (MPI) findings: a preliminary study

Introduction: The product of heart rate and systolic blood pressure, termed as rate-pressure product (RPP), is a very reliable indicator of myocardial oxygen demand and is widely used clinically. There have been previous attempts to describe the relationship between RPP and the onset of pain in angina pectoris. The current study aimed to evaluate the association between RPP results and scan findings.

Materials and methods: In total, 497 patients with suspected coronary artery disease (CAD) underwent gated, single-photon emission computed tomography (SPECT) imaging with dipyridamole, exercise, or dobutamine stress, and were included in this study. Baseline and maximum heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and electrocardiogram (ECG) results were recorded. The rate-pressure product (RPP) was calculated as the product of heart rate and systolic arterial pressure for both baseline and maximum measures. The difference between the RPP max and the basal RPP is known as the RPP reserve. Researchers also obtained semi-quantitative analyses of myocardial perfusion imaging (MPI), using gated software, demographic information, risk factors of CAD, and pretest likelihoods of CAD using nomograms.

Result: Four hundred and ninety-seven cases, including 426 patients with dipyridamole stress, 59 with exercise stress, and 12 with dobutamine stress, underwent myocardial perfusion imaging. Scan results were positive in 194 (45.5%) and negative in 232 (54.5%) patients with dipyridamole stress. In patients with exercise stress, the scan was positive in 24 (40.7%) cases and negative in 35 (59.3%) cases. In dobutamine stressed patients, the scan was positive in 6 (50%) cases and negative in the 6 remaining cases. Dipyridamole stress resulted in a significant difference between HR at rest and at maximum (28.95 ± 24.53, p-value<0.0001), between systolic BP at rest and maximum (6.75 ± 12.50, p-value<0.0001) and between diastolic BP at rest and maximum (1.45 ± 5.80; p-value<0.0001). There was a significant correlation between sum stress scores (SSS) and reserved RPP (r= −0.12, p-value<0.001) which, in dipyridamole patients, was r=−0.18, p-value=0.0001). In addition, there was a significant association between reserved RPP and risk of CAD (p-value<0.001). In the patients with dipyridamole stress, the ejection fraction (EF) change (odds ratio =0.92; 95% CI: 0.86-0.98; p=0.01), reserve RPP (odds ratio =1.00; 95% CI: 1.00-1.00; p=0.04), risk of CAD (odds ratio =5.80; 95% CI: 3.21-10.50; p<0.0001) and age (odds ratio =0.94; 95% CI: 0.89-0.98; p=0.01) were associated significantly with MPI results, using multiple logistic regressions.

Conclusion. The study demonstrated that RPP is associated with MPI findings using gated SPECT imaging with dipyridamole stress. However, to confirm this preliminary result, further studies are mandatory.

The cerebrovascular dilatation effects of olprinone, a phosphodiesterase III inhibitor, in comparison with acetazolamide—a pliot study

To examine the effects of olprinone, a phosphodiesterase III inhibitor, on cerebral blood flow (CBF), we compared the effects of olprinone on CBF to that of acetazolamide. Using technetium-99m-ethyl cysteinate dimer (99mTc-ECD) brain SPECT, we measured regional CBF (rCBF) at 33 sites, including 16 right and left pairs of non-infarct cerebral cortexes, in seven stroke patients (66.0+/-3.2 years) in a resting state and 15 min after the administration of acetazolamide. Within 1 week, rCBF at each site was measured 15 min after the initiation of olprinone infusion. Resting rCBF showed a significant negative correlation with the change in rCBF (DeltaCBF) during olprinone infusion (r = -0.43, P=0.013), but no significant correlation was seen following acetazolamide administration. The difference in rCBF between the right and left cortex increased more following acetazolamide administration (14.1+/-10.9 ml/(min 100 g)) than during olprinone infusion (5.4+/-4.8 ml/(min 100 g), P=0.013). The rCBF at four regions of interest (ROI) with low-resting CBF (< 49 ml/(min 100 g)) further decreased following the administration of acetazolamide. The vasodilatory effects of olprinone are dependent on resting CBF instead of on the intracerebral steal phenomenon that occurs with acetazolamide.

Olprinone: a phosphodiesterase III inhibitor with positive inotropic and vasodilator effects

Olprinone is a newly developed phosphodiesterase III inhibitor characterized by several properties. First, olprinone has positive inotropic and vasodilator actions and improves myocardial mechanical efficiency. Second, olprinone augments cerebral blood flow by a direct vasodilatory effect on cerebral arteries. The cerebrovascular reactivity to olprinone is marked in patients with impaired cerebral circulation. Third, olprinone selectively improves carotid artery distensibility, which may be attributable to differences in the arterial structural components or the reactivity of smooth muscle cells to olprinone. Fourth, olprinone improves inadequate redistribution of brain perfusion and may prevent cerebral metabolic abnormalities in heart failure.

Effects of olprinone, a phosphodiesterase 3 inhibitor, on regional cerebral blood flow of cerebral cortex in stroke patients

The effects of olprinone (0.2 microg/kg per minute, i.v.) on cerebral blood flow were examined using technetium-99m-ethyl cysteinate dimer (99mTc-ECD) brain single-photon emission computed tomography in 14 stroke patients (69.0 +/- 5.6 years) and 12 normal subjects (68.1 +/- 6.2 years). The regional cerebral blood flow of the cerebral cortex was measured at six sites for each stroke patient (stroke group: n = 68, excluding 16 infarct areas confirmed on computed tomography image) and for each normal subject (normal group: n = 72). 99mTc-ECD brain single-photon emission computed tomography was repeated as the baseline 7 days after olprinone treatment study. The percent increment of the rCBF was 14.4 +/- 9.8% in the normal group and 10.7 +/- 11.7% in the stroke group (p = 0.002). The baseline value of the regional cerebral blood flow had a significant negative correlation with the increase of the regional cerebral blood flow in the normal group (r = -0.73, p < 0.0001) and in the stroke group (r = -0.43, p < 0.001). Although olprinone could dilate the cerebral vessels of stroke patients as well as those of normal subjects, smooth muscle dysfunction of the cerebral vessels due to advanced arteriosclerosis may reduce this effect.