Hypertension
-
Systolic blood pressure (SBP) variability is increased and R-R interval variability is reduced in the elderly. Little is known, however, about how SBP and R-R interval variabilities change in the very elderly. More important, however, it is not known which frequency components of SBP and R-R interval variability are affected significantly. ⋯ Therefore, in very elderly subjects a reduction in overall R-R interval variability is accounted for by a reduction in all of its frequency components. The accompanying increase in overall BP variability, however, results from a nonhomogeneous behavior of its frequency components, which consists of an increase in the very low frequency and a concomitant reduction in the higher frequency powers. The mechanisms responsible for these changes may be complex, but at least they may in part reflect the baroreflex impairment and autonomic dysfunction that characterize aging.
-
The sensitivity of the myofilaments to Ca2+ is increased during agonist-induced contraction of vascular smooth muscle. Given the important contribution of vascular tone to the elevation of peripheral resistance observed in genetic hypertension, we have investigated whether alterations in myofilament Ca2+ sensitivity occur in small arteries from spontaneously hypertensive rats (SHR) and age-matched Wistar-Kyoto (WKY) controls during the developmental and established phases of hypertension. Segments of mesenteric, renal, and femoral artery with an average lumen diameter <300 microm from 5- or 20-week-old rats were mounted in a wire myograph. ⋯ We have demonstrated that the sensitivity of the myofilaments to Ca2+ and ET-1- or NE-induced Ca2+ sensitization is not different in permeabilized small mesenteric, renal, or femoral arteries from SHR compared with WKY controls. Only in SHR mesenteric arteries at 20 weeks of age was there evidence of increased active tension in response to maximal Ca2+, despite structural differences, consistent with increased muscle mass in femoral arteries from SHR. We conclude that it is unlikely that a ubiquitous abnormality of the sensitivity of the contractile apparatus to Ca2+ or agonist-induced Ca2+ sensitization in vascular smooth muscle underlies the elevated total peripheral resistance associated with hypertension.
-
We investigated the mechanism of action of the ACE inhibitor-induced increase in cardiac capillary length density. Stroke-prone spontaneously hypertensive rats were treated prenatally and up to the age of 20 weeks with the ACE inhibitor ramipril (0.01 and 1 mg/kg per day PO) and the AT1 receptor antagonist losartan (30 mg/kg per day PO). The contribution of endogenous bradykinin potentiation to the ACE inhibitor actions was assessed by cotreatment with the bradykinin B2-receptor antagonist Icatibant (0.5 mg/kg per day, SC via osmotic minipumps) from 6 to 20 weeks of age. ⋯ Losartan prevented hypertension and left ventricular hypertrophy but did not significantly alter cardiac capillary length density (3429 +/- 309 mm/mm3; n = 7). Our results demonstrate that chronic ACE inhibitor treatment can increase cardiac capillary length density in stroke-prone spontaneously hypertensive rats independently of a reduction in blood pressure or left ventricular hypertrophy. This effect is related to the ACE inhibitor-induced potentiation of endogenous bradykinin since it was prevented by chronic bradykinin B2-receptor blockade and was not observed following antihypertensive treatment with the AT1-receptor antagonist losartan.
-
The prevalence and clinical picture of hypertensive urgencies and emergencies in an emergency department are poorly known. The aim of the present study was to evaluate the prevalence of hypertensive crises (urgencies and emergencies) in an emergency department during 12 months of observation and the frequency of end-organ damage with related clinical pictures during the first 24 hours after presentation. Hypertensive crises (76% urgencies, 24% emergencies) represented more than one fourth of all medical urgencies-emergencies. ⋯ Hypertension that was unknown at presentation was present in 8% of hypertensive emergencies and 28% of hypertensive urgencies. In conclusion hypertensive urgencies and emergencies are common events in the emergency department and differ in their clinical patterns of presentation. Cerebral infarction and acute pulmonary edema are the most frequent types of end-organ damage in hypertensive emergencies.
-
Because of the clinical and experimental utility of continuous finger blood pressure measurements and the need for accuracy, we tested the performance of a new hydraulic device in 22 consecutive hypertensive subjects during physiological and pharmacological interventions. Ipsilateral brachial intra-arterial pressure was monitored during rest, Valsalva's maneuver, static handgrip, and mental arithmetic and after sublingual glyceryl trinitrate. In excess of 40,000 blood pressure values were analyzed. ⋯ Linear drift (millimeters of mercury per minute) of finger pressure was greater (P < .001) for systolic than diastolic pressure during static exercise and math and after glyceryl trinitrate. Coefficients of determination for blood pressure ranged from 0.4 +/- 0.3 to 0.8 +/- 0.3 during the tasks. We conclude that (1) noninvasive finger blood pressure faithfully follows intra-arterial changes but with clinically relevant offsets, (2) this technique is best suited for assessing pressure changes, (3) physiological and pharmacological interventions do not consistently affect finger pressure accuracy, (4) many reports of finger blood pressure measuring devices are based on direct readings obtained with inadequate system response characteristics, and (5) the tested instrument falls short of the standard requirements (bias < or = 5 +/- 8 mm Hg) for devices that measure intermittently.