[Role of nitrates in pharmacologic modulation of reflected waves and their significance in the treatment of arterial hypertension in the elderly]

OBJECTIVE

To analyse the efficacy of a sustained release form of isosorbide mononitrate in the treatment of isolated systolic hypertension in the elderly.

PATIENTS

24 patients suffering from essential hypertension and with an average age of 68.5 +/- 1.1 years were studied: 20 male and four female patients, all with isolated systolic hypertension (systolic blood pressure (SBP) > 160 mmHg and diastolic blood pressure (DBP) < 90 mmHg). None of the patients had received pharmacological treatment for their hypertension. None were receiving other medication or displayed concomitant pathologies.

METHODS

Assessment of all the patients was made with the measurement of their occasional blood pressure, ambulatory measurement of blood pressure and the measurement of pulse wave velocity in two arterial zones (carotid-femural) by mecanography before and after thirty days of monotherapy with a single 50 mg dose of a sustained release form of isosorbide mononitrate. Four patients were withdrawn from tests due to signs of intolerance to the drug.

RESULTS

A fall in occasional blood pressure was recorded, with statistical significance in relation to SBP only: SBP-192 +/- 15.5-->164 +/- 10.2 mm Hg (p < 0.001); DBP-85 +/- 4.2-->83 +/- 5.4 mm Hg. Ambulatory blood pressure readings also showed a significant drop in average SBP readings over the 24 hours: SAP 152.6 +/- 13.6-->140.5 +/- 15.4 mm Hg (p < 0.03); DBP 77.2 +/- 8.7-->72.3 +/- 5.47 mm Hg. No significant changes in pulse wave velocity were recorded for the zones studied: carotid-femural -20.8 +/- 6.0-->21.7 +/- 5.1 m/sec; femural-foot -4.5 +/ -1.4-->4.4 +/- 2.6 m/sec; a marked alteration in the morphology of arterial pulse in the aortic zone was observed, however, with a clear levelling off and reduction of the systolic peak.

CONCLUSION

Treatment with nitrates may be a new and effective alternative for the treatment of the age group in question. It acts specifically on the pathophysiological mechanisms of isolated systolic arterial hypertension in the elderly. Changes in reflected wave velocity (retrogrades) seem to cause the significant reduction in SBP, observed in this group of patients.

[24-hour arterial pressure study and diabetic neuropathy and angiopathy of the lower limbs]

AIMS

To study the circadian variation of BP in diabetics with chronic late complications (autonomic neuropathy, peripheral neuropathy and macroangiopathy of the lower limbs).

PATIENTS AND METHODS

We studied 35 NIDDM patients, 22 male and 13 female, with a mean age of 62.17 +/- 8.66 years, all with hypertension (HBP) or with BP levels close to normal, many of them under anti-hypertensive therapy (mean BP in clinical measurements: 164 +/- 23.16 mmHg systolic and 92.14 +/- 11.06 mmHg diastolic). Twenty-four suffer from autonomic neuropathy, 23 from peripheral neuropathy and 11 from macroangiopathy of the lower limbs. The control group is composed of 10 patients with essential HBP without other observable pathology, with a mean age of 68.5 +/- 3.63 years and BP in clinical measurements: systolic 192 +/- 15.49 mmHg and diastolic 88 +/- 4.21 mmHg (without any previous therapy). The record of the BP circadian profile was made, with the use of a Spacelab monitor, model 90207, 5 days after anti-hypertensive therapy was suspended.

RESULTS

The mean BPs in 24 hours were: control group-systolic BP 152.6 +/- 13 mmHg and diastolic 79.8 +/- 13 mmHg; diabetics-systolic BP 136.82 +/- 15 mmHg and diastolic 77.4 +/- 8 mmHg. The daily and nocturnal mean BPs were 158.5 +/- 8.5 and 146 +/- 8.4 mmHg (systolic) and 82.8 +/- 5.7 and 70.9 +/- 5.1 mmHg (diastolic) in the control group, while they were, in diabetics, 141.3 +/- 15.7 and 135.6 +/- 16.6 mmHg (systolic) and 79.6 +/- 7.1 and 72 +/- 8.2 mmHg (diastolic). In diabetic patients, considering the groups with and without autonomic neuropathy, the difference between daily and nocturnal mean BP was 1.6 vs 9.4 mmHg systolic and 4.9 vs 9.4 mmHg, diastolic.

CONCLUSIONS

In both groups, the mean BP levels in 24 hours were notoriously lower than those obtained from the clinical measurements: the differences were 40 mmHg (control group) and 27.2 mmHg (diabetics) for systolic BP and 8.2 mmHg (control group) and 14.7 mmHg (diabetics) for diastolic. The BP circadian profiles show a lower variability, with absence of the nocturnal reduction, specially evident in diabetic patients with autonomic neuropathy versus other groups.

[Pulse wave velocity as initial marker of atherosclerosis]

OBJECTIVE

To evaluate the influence of hypercholesterolaemia on arterial distensibility.

MATERIAL AND METHODS

43 male New Zealand White rabbits, with similar ages and weights, were included in the present study. The animals were divided in two groups: Group A (n = 15) was fed a normal diet; Group B (n = 28) was fed normal diet plus 0.1% cholesterol. at the beginning and after 6 and 9 months, blood samples were obtained for determination of serum cholesterol (total, esterified, LDL) and Triglyceride levels. Pulse wave velocity (PWV) was also evaluated, by mecanography, after 6 and 9 months of the beginning of the experiment. After 6 months (Group A = 4 and Group B = 7) and 9 months (Group A = 6 and Group B = 7) of the experiment, some animals were killed for anatomopathological studies.

RESULTS

Major differences were obtained between the two groups, specially in what concerns to LDL and cholesterol levels (p < 0.001). There was also a remarkable difference in PWV between the two groups (6.078 +/- 0.162/9.002 +/- 0.196 m/s at 6 months and 7.639 +/- 0.590/9.557 +/- 0.543 m/s at 9 months) from the rabbits fed normal or cholesterol diet, respectively. The anatomical lesions were only significant after 9 months. However there was a decrease in aorta internal diameters at thoracic and renal levels at 6 months (34% and 53%) and at 9 months (29% and 33%), without significant changes in their thickness. In the heart, the left ventricle (LV) had a significant thickness increase after 6 months (about 43%).

CONCLUSIONS

These data indicate that even before anatomical lesions had occurred, important functional changes are present, in the arterial wall. Then, the evaluation of the PWV could be a promising non-invasive diagnostic method of early atherosclerosis, with obvious implications concerning its prophylaxis and therapy.