Clinical relevance of nighttime blood pressure and of daytime blood pressure variability.

BACKGROUND: The purpose of this study was to assess whether hypertensive target organ damage is related to average nighttime blood pressure (BP) and to BP variability. METHODS: Sixty-seven normotensive subjects and 171 borderline, 309 mild, 140 moderate, and 41 severe hypertensive patients were studied with noninvasive ambulatory BP monitoring. Each subject was assigned a target organ damage score of 0 to 5 on the basis of funduscopic changes and degree of left ventricular hypertrophy calculated from electrocardiogram and chest roentgenogram. RESULTS: When the 728 subjects were subdivided into five classes of increasing daytime BP, in each class a significantly higher degree of target organ damage was present in the subjects with higher nighttime diastolic BP. A similar, although nonsignificant, trend was observed in the subjects with higher nighttime systolic BP. In particular, higher nighttime BP levels were accompanied by a more severe degree of left ventricular hypertrophy. As for variability, subjects with higher daytime systolic BP SD, but not with higher daytime diastolic SD, displayed a more severe degree of target organ damage; this was accounted for by a higher degree of retinal abnormalities. The association between target organ damage and systolic BP SD was present both in men and women, while that with nighttime BP was present only in men. No relationship was found between degree of cardiovascular complications and peaks of pressure. CONCLUSIONS: These results suggest that a reduced day-night BP difference and an increased daytime BP variability, evaluated as the SD, are associated with a higher degree of hypertensive cardiovascular complications. Whether this BP profile is the cause or the consequence of target organ damage remains to be established.

Effect of timing of administration on the plasma ACE inhibitory activity and the antihypertensive effect of quinapril.

To assess whether timing of administration can influence the antihypertensive effect of quinapril, 18 patients with hypertension were studied with noninvasive ambulatory blood pressure monitoring. Quinapril, 20 mg, was given at 8 AM or 10 PM for 4 weeks in a double-blind crossover fashion. To study the pattern of angiotensin converting enzyme (ACE) inhibition with the two treatment regimens, plasma ACE activity was measured in seven subjects 2, 4, 8, 12 and 24 hours after quinapril administration. The 24-hour blood pressure profiles showed a more sustained antihypertensive action with the evening administration of quinapril compared with the morning administration of quinapril; as with the morning administration, a partial loss of effectiveness was observed during nighttime hours. Measurement of ACE activity showed that evening administration caused a less pronounced but a more sustained decline of plasma ACE. These findings show that 20 mg quinapril given once daily is effective in lowering blood pressure levels throughout a 24-hour period. The evening administration seems to be preferable because it causes a more favorable modulation of ACE inhibition and therefore determines a more homogeneous 24-hour blood pressure control.

[Reproducibility of ambulatory blood pressure monitoring]. / Riproducibilità della misurazione della pressione arteriosa con monitoraggio incruento.

Short-term blood pressure variability has been studied extensively with monitoring techniques. To assess whether or not and to what extent average 24-hour blood pressure varies when repeatedly recorded, 12 mild to moderate hypertensive subjects underwent 3 non-invasive blood pressure monitorings at monthly intervals. When the average 24-hour blood pressure of the whole group was evaluated no substantial differences were found between the 3 recordings, even though slightly lower blood pressure values were recorded at the first monitoring. However, when the within-period comparison was studied in the single patients, remarkable discrepancies of up to 20.9/15.8 mmHg were detected. Systolic and diastolic blood pressure variations greater than or equal to 5 mmHg were recorded in 58% of the subjects. These differences were unrelated to the number of faulty readings. Casual blood pressure varied even to a greater extent between the first and the subsequent visits; no correlation was found between casual and 24-hour blood pressure variations. The results of the present study indicate that ambulatory blood pressure may vary even to a great extent when repeatedly recorded. This finding entails important clinical implications, as the evaluation of the hypertensive patient is usually made with a single blood pressure monitoring.

[The normal limits of arterial pressure registered with portable methods: an approach to the problem]. / Limiti di normalità della pressione arteriosa registrata con metodiche portatili: un approccio al problema.

In the present paper the problem of the normalcy limits of whole-day ambulatory blood pressure has been faced by evaluating the difference between casual and ambulatory blood pressure in a population of 522 subjects with blood pressure values covering the whole blood pressure range. On the basis of the casual blood pressure levels, 60 subjects were normotensives, 110 borderline hypertensives, 214 mild, 103 moderate and 35 severe hypertensives. The differences between casual and median 24-hour blood pressure averaged 18.4/9.6 mmHg. The difference between casual and median day-time was 14.2/6.7 mmHg. This difference was independent from the ambulatory blood pressure values and unrelated to the sex or age of subjects. The upper normal limits of ambulatory blood pressure were established by subtracting the above differences from the normal limits established by the WHO for casual blood pressure (140/90 mmHg). For 24-hour blood pressure the upper limits were 121.6/80.4 mmHg and for day-time blood pressure these were 125.8/83.3 mmHg. Contrary to previous studies conducted on normotensive populations with this approach the selection of patients based on casual blood pressure is avoided and the WHO normalcy limits are taken into account.

[Clinical significance of nocturnal blood pressure and blood pressure variability: analysis of 522 cases]. / Significato clinico della pressione notturna e della variabilità pressoria: analisi di 522 casi.

Purpose of the study was to investigate whether and to what extent blood pressure variability and average night-time blood pressure are related to cardiovascular complications in hypertension. To this aim 60 normotensive and 462 hypertensive subjects were studied by means of non-invasive 24 hour blood pressure monitoring, using either the Avionics, or the ICR Spacelabs, or the Takeda system. Each subject was attributed a target organ damage score on the basis of 12-lead electrocardiogram, chest X-ray and fundoscopy, starting from 0 (no damage) up to 5 (maximum degree of damage). The 522 subjects were subsequently subdivided into 5 classes of increasing average daytime diastolic blood pressure. In each class a higher degree of cardiovascular complications was present in the subjects with the higher blood pressure variability and the higher average night-time blood pressure. From these results it may be inferred that both blood pressure variability and night-time blood pressure are related to the degree of target organ damage in hypertension. This stresses the importance of recording blood pressure throughout the 24 hours.