Correlation of pathophysiology and pharmacotherapy in primary hypertension

Association of Blood Pressure Variability Ratio With Glomerular Filtration Rate Independent of Blood Pressure and Pulse Wave Velocity

BACKGROUND

Blood pressure variability ratio (BPVR)(derived from within-subject SD of 24-hour ambulatory blood pressure [BP]) predicts all-cause mortality independent of BP and has a similar prognostic ability to ambulatory arterial stiffness (AASI). Whether BPVR, and AASI, offer prognostic information beyond measurements of arterial stiffness at a given pressure, as indexed by pulse wave velocity (PWV), is not known.

METHODS

We assessed whether BPVR and AASI were associated with indices of subclinical organ damage (TOD) [estimated glomerular filtration rate (eGFR), left ventricular mass index, early-to-late transmitral velocity (E/A), carotid intima-media thickness (IMT)] independent of BP, and whether BPVR-TOD and AASI-TOD relations were independent of PWV (applanation tonometry) in 772 randomly selected participants from an urban, developing community. AASI was derived from 24-hour diastolic BP vs. systolic BP standard linear regression.

RESULTS

On bivariate analyses, BPVR, AASI, and PWV were correlated with all indices of TOD (P < 0.0005). However, after adjustments for potential confounders including age and 24-hour mean BP, BPVR, and PWV (P < 0.005 to P < 0.0001), but not AASI (P > 0.25), were independently associated with eGFR, but not other indices of TOD. Importantly, the BPVR-eGFR relation was independent of BP variability (P < 0.005) and PWV (P < 0.001).

CONCLUSIONS

BPVR was negatively associated with eGFR independent of mean BP, BP variability, and PWV. Therefore, in the prediction of cardiovascular risk, measurements of arterial stiffening (BPVR) may provide information beyond the impact of arterial stiffness.

Diurnal Variation of Blood Pressure in Elderly Patients with Essential Hypertension

Twenty-one elderly patients with essential hypertension, all over 65 years of age, were subjected to automated noninvasive 24-hour blood pressure measurement. Readings were obtained every 7.5 minutes throughout the day. The data were analyzed with respect to: correlation between office and ambulatory pressure measurements; possible differences in the circadian blood pressure pattern; and the existence of hypertensive or atherosclerotic cardiovascular complications. In all patients, the office systolic pressures were significantly higher than the ambulatory daytime pressures; diastolic pressures were similar. At night, two patterns of blood pressure emerged. In one there was a further fall in both systolic and diastolic pressures to normotensive levels, whereas the other pattern revealed no change in diastolic pressure, although systolic pressure increased significantly to similar levels as measured in the office. The prevalence of hypertensive or atherosclerotic cardiovascular complications in the patients with the first pattern was significantly less than in the group of patients with the second pattern (chi square, P less than 0.025). The data reported herein indicate that ambulatory blood pressure monitoring may help in the overall clinical evaluation of elderly patients with hypertension.

Brachial vs. central systolic pressure and pulse wave transmission indicators: a critical analysis

This critique is intended to provide background for the reader to evaluate the relative clinical utilities of brachial cuff systolic blood pressure (SBP) and its derivatives, including pulse pressure, central systolic pressure, central augmentation index (AI), and pulse pressure amplification (PPA). The critical question is whether the newer indicators add sufficient information to justify replacing or augmenting brachial cuff blood pressure (BP) data in research and patient care. Historical context, pathophysiology of variations in pulse wave transmission and reflection, issues related to measurement and model errors, statistical limitations, and clinical correlations are presented, along with new comparative data. Based on this overview, there is no compelling scientific or practical reason to replace cuff SBP with any of the newer indicators in the vast majority of clinical situations. Supplemental value for central SBP may exist in defining patients with exaggerated PPA ("spurious systolic hypertension"), managing cardiac and aortic diseases, and in studies of cardiovascular drugs, but there are no current standards for these possibilities.

Effect on blood pressure control of switching from valsartan monotherapy to losartan/hydrochlorothiazide in Asian patients with hypertension: results of a multicentre open-label trial

STUDY DESIGN

An open-label, multicentre study was conducted to evaluate the antihypertensive efficacy of a 4-week course of losartan 50 mg plus hydrochlorothiazide 12.5 mg in Asian patients with essential hypertension whose blood pressure had previously been treated with but not controlled by valsartan 80 mg.

METHODS

A total of 237 eligible patients with mean trough sitting diastolic blood pressure (SiDBP) 95-115 mmHg and a mean trough sitting systolic blood pressure (SiSBP) < 190 mmHg entered the baseline period of treatment with valsartan 80 mg/day for 4 weeks. Those (n = 165) whose SiDBP remained > 90 mmHg and who were not excluded for other reasons were then switched to a single-tablet formulation of losartan 50 mg/hydrochlorothiazide 12.5 mg combination once daily for a further 4 weeks.

RESULTS

Mean SiDBP (study primary endpoint) at the end of combination therapy was reduced to 86.9 mmHg from 95.2 mmHg. SiSBP (study secondary endpoint) was reduced to 132.6 mmHg from 140.7 mmHg. Mean reductions after switching from valsartan 80 mg to losartan 50 mg/hydrochlorothiazide 12.5 mg were thus 8.3 and 8.1 mmHg for SiDBP and SiSBP, respectively (p < or = 0.001 for both outcomes). The goal of SiDBP < or = 90 mmHg was attained in 72% of the patients previously not controlled to the same level by valsartan 80 mg/day. Combination therapy with losartan 50 mg/hydrochlorothiazide 12.5 mg was generally well tolerated. Mean compliance with the losartan 50 mg/hydrochlorothiazide 12.5 mg combination was > 99%.

CONCLUSION

These results demonstrate that in Asian patients who do not reach the goal of mean trough SiDBP < or = 90 mmHg with valsartan monotherapy at 80 mg once-daily, switching to a single-tablet combination of losartan 50 mg/hydrochlorothiazide 12.5 mg once-daily is well tolerated, provides effective control of blood pressure and is an excellent choice to achieve blood pressure reduction goals.

Mechanisms of Hypertension Associated With BAY 43-9006

Purpose

BAY 43-9006 (sorafenib) is an inhibitor of Raf kinase, the vascular endothelial growth factor (VEGF) receptor-2, and angiogenesis in tumor xenografts. The current study investigated the incidence, severity, and mechanism of blood pressure (BP) elevation in patients treated with BAY 43-9006.

Patients and Methods

Twenty patients received BAY 43-9006 400 mg orally twice daily. BP and heart rate were measured at baseline and then every 3 weeks for 18 weeks. VEGF, catecholamines, endothelin I, urotensin II, renin, and aldosterone were measured at baseline and after 3 weeks of therapy. We assessed vascular stiffness at baseline, after 3 to 6 weeks of therapy, and again after 9 to 10 months of therapy.

Results

Fifteen (75%) of 20 patients experienced an increase of ≥ 10 mmHg in systolic BP (SBP), and 12 (60%) of 20 patients experienced an increase of ≥ 20 mmHg in SBP compared with their baseline value, with a mean change of 20.6 mmHg (P < .0001) after 3 weeks of therapy. There were no statistically significant changes in humoral factors, although there was a statistically significant inverse relationship between decreases in catecholamines and increases in SBP, suggesting a secondary response to BP elevation. Measures of vascular stiffness increased significantly during the period of observation.

Conclusion

Treatment with BAY 43-9006 is associated with a significant and sustained increase in BP. The lack of significant change in circulating factors suggests that these humoral factors had little role in the increase in BP.

Systolic and diastolic blood pressure lowering as determinants of cardiovascular outcome

Based on individual patient data, we performed a quantitative overview of trials in hypertension to investigate to what extent lowering of systolic blood pressure (SBP) and diastolic blood pressure (DBP) contributed to cardiovascular prevention. We selected trials that tested active antihypertensive drugs against placebo or no treatment. Our analyses included 12,903 young (30 to 49 years of age) patients randomized in 3 trials and 14,324 old (60 to 79 years of age) and 1209 very old (> or =80 years of age) patients enrolled in 8 trials. Antihypertensive treatment reduced SBP/DBP by 8.3/4.6 mm Hg in young patients, by 10.7/4.2 mm Hg in old patients, and by 9.4/3.2 mm Hg in very old patients, respectively, resulting in ratios of DBP to SBP lowering of 0.55, 0.39, and 0.32, respectively (P=0.004 for trend with age). In spite of the differential lowering of SBP and DBP, antihypertensive treatment reduced the risk of all cardiovascular events, stroke and myocardial infarction in the 3 age strata to a similar extent. Absolute benefit increased with age and with lower ratio of DBP to SBP lowering. Furthermore, in patients with a larger-than-median reduction in SBP, active treatment consistently reduced the risk of all outcomes irrespective of the decrease in DBP or the achieved DBP. These findings remained consistent if the achieved DBP averaged <70 mm Hg. In conclusion, our overview suggests that antihypertensive drug treatment improves outcome mainly through lowering of SBP.

Arterial stiffness and the systolic hypertension syndrome

PURPOSE OF REVIEW

This review is intended to provide the background for a new comprehensive hemodynamic view of the syndrome of systolic or wide pulse pressure hypertension and its hallmark abnormality: increased central arterial stiffness.

RECENT FINDINGS

Studies of the pathogenesis of systolic hypertension have lagged. This review describes the systolic hypertension syndrome as a complex set of hemodynamic maladaptations that include stiff central arteries, normal peripheral arteries with variable pressure amplification characteristics, arteriolar constriction, microcirculatory rarefaction, metabolic abnormalities, cardiac hypertrophy, and increased blood pressure variability. Because the structural and functional properties of arteries of different caliber are highly heterogeneous and vary with aging and disease, simple measurements such as standard brachial artery blood pressure, brachial pulse pressure, or mean arterial pressure are inadequate to provide meaningful insight into the pathophysiology of the syndrome. Additional parameters developed to describe changes in arterial mechanics (arterial compliance or stiffness, elastic modulus, impedance, pulse wave velocity, augmentation index, and pulse pressure amplification) are intrinsically limited and are directly or indirectly pressure-dependent. Quantitation of central arterial stiffness provides a modest increment in cardiovascular and renal risk stratification.

SUMMARY

Better clinical management of systolic hypertension depends on greater insight into the syndrome as a whole, more critical analysis of existing techniques, and the development of new approaches.

Office blood pressures, arterial compliance characteristics, and estimated cardiac load

Because of rising interest in new methods to detect arterial diseases, we compared data from 3 different compliance-related techniques to measure arterial stiffness: systolic pulse contour analysis, diastolic pulse contour analysis (modified Windkessel model), and muscular (brachial) artery compliance by cuff plethysmography. Variables measured in the sitting position were compared with each other, with clinic blood pressures (BPs), and with the cardiac time-tension integral (CTTI) in 63 established hypertensive and 28 age-matched normotensive subjects. Hypertensives demonstrated marginal reductions in C(1) (thought to represent reduced large vessel compliance) and increased central systolic BP augmentation. In contrast, muscular artery compliance tended to be greater in the hypertensives despite normal brachial arterial diameters. C(2), suggested to be an indicator of small artery properties, was similar in both groups. CTTI was strongly related to systolic pressure (r=0.81), integrated mean arterial pressure (r=0.83), and systolic pressure-heart rate product (r=0.85) and was less strongly related to diastolic (r=0.71) or pulse pressure (r=0.57). Weak correlations were observed between CTTI and measured compliance-related variables, which also showed absent or weak correlations among themselves. We conclude that the weak relationships among BP and compliance-related variables could be due to intrinsic differences in the properties of large and small arteries, theoretical methodological weaknesses, measurement artifacts, or intrinsic hemodynamic differences of the sitting position. At present, compliance-related variables provide little additional advantage over cuff BP in the office estimation of cardiac work.

Is there a preferred antihypertensive therapy for isolated systolic hypertension and reduced arterial compliance?

Isolated systolic hypertension (ISH) is the most common type of hypertension and the most difficult type to control with antihypertensive therapy. ISH, by definition, is wide pulse pressure hypertension resulting largely from excessive large artery stiffness and representing an independent risk factor for cardiovascular disease in the older aged population. Two major intervention studies of ISH have shown significant benefit in reducing systolic blood pressure with active drug therapy, including thiazide diuretics and calcium receptor antagonists. The optimal treatment strategy is to maximize reduction in systolic blood pressure and to minimize reduction in diastolic blood pressure, thereby reducing pulse pressure. All classes of antihypertensive drugs reduce pulse pressure by means of lowering peripheral resistance, but certain drugs like nitrates, angiotensin converting enzyme inhibitors, and other drugs affecting the renin-angiotensin system have multiple actions that improve large artery stiffness and early wave reflection and are especially useful in treating ISH in the elderly.

Arterial baroreceptor-cardiac reflex sensitivity in the elderly

Uncertainty still remains regarding the differing effects of blood pressure and age on baroreceptor-cardiac reflex sensitivity in elderly individuals; these differences are at least partly due to the differing methods and subject groups used in previous studies. We sought to resolve these issues by examining baroreflex sensitivity in 54 subjects aged 70 +/- 1 years (mean +/- SE; range, 60 to 81) divided into groups with combined systolic-diastolic hypertension (CH group, n = 16), isolated systolic hypertension (ISH group, n = 16), or normotension (NT group, n = 22). Baroreflex sensitivity was quantified from the pulse interval and blood pressure responses to the Valsalva maneuver and pressor (phenylephrine) and depressor (sodium nitroprusside) stimuli. Baroreflex sensitivity was significantly reduced in the two hypertensive groups but did not differ between them (Valsalva maneuver: CH group, 1.9 +/- 0.3 ms/mm Hg; ISH group, 2.8 +/- 0.5; NT group, 4.4 +/- 0.4; phenylephrine: CH group, 3.1 +/- 0.6; ISH group, 3.5 +/- 0.7; NT group, 7.7 +/- 1.0; sodium nitroprusside CH group, 2.1 +/- 0.3; ISH group, 3.6 +/- 0.8; NT group, 5.4 +/- 0.3; all P < .05 for comparison with the NT group). Thus, this study demonstrated reductions in baroreflex sensitivity with hypertension in elderly subjects consistent across all methods but with no difference between subjects with combined hypertension and isolated systolic hypertension matched for similar systolic pressure. Baroreflex sensitivity was related only to the level of systolic pressure independent of diastolic pressure or age. If elderly subjects with isolated systolic hypertension have a greater reduction in large-artery compliance than combined hypertensive subjects with similar systolic pressure, this does not appear to lead to further reductions in baroreflex sensitivity in these individuals.

Pulse pressure and resistance artery structure in the elderly

There has been recent interest in the possibility that resistance vessel structural adaptation in hypertension may be more closely related to pulse pressure than to other blood pressure parameters. We investigated the relation between blood pressure and resistance vessel structure in a group of subjects from an age group (older than 60 years) in which a widening of pulse pressure is a typical finding and characterized blood pressure parameters using 24-hour ambulatory blood pressure monitoring. We studied resistance vessels retrieved from biopsies of skin and subcutaneous fat taken from the gluteal region of 32 subjects under local anesthesia (age, 70 +/- 1 years [mean +/- SEM], 21 of whom were hypertensive and 11 normotensive. Media-lumen ratio was higher in the hypertensive than the normotensive subjects (18.6 +/- 1.6% versus 12.8 +/- 1.2%, P < .01) and correlated with age (r = .44, P < .05), clinic systolic pressure (r = .35, P < .05), 24-hour systolic pressure (r = .40, P < .05), and 24-hour pulse pressure (r = .56, P < .001). Stepwise multivariate regression analysis identified clinic and 24-hour pulse pressure as the only significant predictors of media-lumen ratio independent of age, other parameters of clinic blood pressure, and blood pressure variability (R2 = 41%, P < .05). These findings confirm those from animal models of hypertension in demonstrating the importance of pulse pressure in relation to cardiovascular structural adaptation and have important implications for the goals of treatment of hypertension in the elderly.

Red blood cell sodium and potassium concentration and blood pressure. The Gubbio Population Study

The relations of red blood cell sodium (RBC Na) and potassium (RBC K) concentrations to blood pressure and prevalence of hypertension were assessed for 1805 men and women, aged 25 to 74 years, who participated in the baseline examination of the Gubbio Population Study in north central Italy. In men, in univariate analyses, RBC Na concentration was not significantly related to systolic or diastolic blood pressure, while RBC K concentration was significantly and inversely related to blood pressure. In women RBC Na values correlated significantly and directly with systolic and diastolic pressure, but RBC K concentration was not significantly related to blood pressure. Results of the multivariate analyses indicated in men a significant independent and inverse relationship of RBC K concentration with hypertension and blood pressure, and in women a significant positive association of RBC Na concentration with hypertension. RBC Na did not relate independently to either systolic or diastolic blood pressure in men or women. Age-specific analyses suggested that the relationships between RBC K level and blood pressure in men and the relationship between RBC Na level and hypertension in women were stronger in older (age 55 to 74 years) compared to younger participants (25 to 54 years). These findings indicate that the associations of RBC Na and K concentrations and hypertension may be sex and age specific. The nature of these gender- and age-specific associations remains to be clarified. Prospective data are also needed for further clarification of the relation of intracellular Na metabolism to the etiology of hypertension.

Treating isolated systolic hypertension in the elderly

OBJECTIVE

To review the prevalence, pathophysiology, vascular risk, and treatment of isolated systolic hypertension (ISH) in the elderly.

DATA SOURCE

A MEDLINE search of the English language literature was performed to identify pertinent literature. Key search terms were hypertension, systolic, and elderly.

STUDY SELECTION

All studies available evaluating drug therapy for ISH or hypertension in the elderly as well as review articles discussing the prevalence, pathophysiology, and treatment of ISH were selected.

SYNTHESIS

ISH occurs commonly in the elderly and is associated with increased risk for cardiovascular and cerebrovascular disease. Although the mechanism for ISH in the elderly is not completely understood, the primary factor is believed to be a reduction in arterial compliance. Results of the Systolic Hypertension in the Elderly Program demonstrated that control of ISH using a diuretic alone or in combination with a beta-blocker significantly reduced the incidence of strokes and cardiovascular events. In this trial, drug therapy was found to be safe and generally well tolerated by the elderly. Newer antihypertensive agents such as the calcium-channel blockers and angiotensin-converting enzyme (ACE) inhibitors have also been shown to effectively lower SBP in the elderly, but the effects on long-term morbidity and mortality are not yet known.

CONCLUSIONS

ISH is an important risk factor for vascular disease in the elderly. Accurate diagnosis and effective drug treatment can result in significant reductions in the risk of cardiovascular and cerebrovascular events. Based on the available trial data, diuretics appear to be the drugs of first choice unless there are contra-indications. If combination drug therapy is required, beta-blockers should be considered although their contribution to vascular risk reduction remains less clear. Additional studies are needed to determine the long-term benefits and risks of alternative antihypertensive agents such as calcium-channel blockers and ACE inhibitors.

Hemodynamic response to orthostatic stress in the elderly with systolic systemic hypertension before and after long-term thiazide therapy

The hemodynamic effects of orthostatic stress in elderly subjects with systolic hypertension were studied before and after long-term hydrochlorothiazide therapy (50 mg daily). Sixteen nondiabetic men aged 70 +/- 1 (SE) years participated in the study initially, and 12 completed 1 year of therapy. Patients underwent 45 degrees head-up incline on a tilt table before, after 1 month and after 1 year of therapy. Hemodynamic variables were measured in the following situations: (1) the supine position, (2) immediately after completion of passive 45 degrees head-up position at 0 minute, (3) at 15 minutes in the tilted state while patients performed intermittent foot movements to minimize gravitational pooling and simulate the standing position outside the laboratory, and (4) after returning to the supine position. Systolic and diastolic blood pressure (BP) decreased significantly after 1 month of therapy, and this reduction was maintained up to 1 year in all aforementioned body positions, with the exception of diastolic BP at 0 minute of tilt, which was significant at 1 year only. Before therapy was begun, there was a significant reduction in systolic BP immediately after completion of tilting; however, this was statistically insignificant both at 1 month and 1 year of therapy. Thus, the data may help dispel the concern of exacerbating the hypotensive response to orthostatic stress in patients with systolic hypertension after long-term thiazide diuretic therapy.

Twenty-four-hour variation of blood pressure in vascular dementia of the Binswanger type

Using a noninvasive portable blood pressure recorder, we compared 24-hour variations of blood pressure among 1) 35 patients with Binswanger-type dementia, 2) 43 with lacunar-type dementia, 3) 26 with a single lacunar stroke, and 4) 30 controls. Each group was divided into antihypertensive-treated and -untreated subgroups. Among the untreated subgroups, patients with Binswanger-type dementia had significantly greater 24-hour mean systolic blood pressures, 24-hour systolic blood pressure standard deviations, and maximal systolic blood pressure variations than the controls (p less than 0.05). Among the treated patients, blood pressure variability increased similarly in all subgroups with cerebrovascular lesions compared with the controls (p less than 0.05). The nocturnal blood pressure decreases seen in the controls were absent among both untreated and treated patients with Binswanger- or lacunar-type dementia (p less than 0.05). Our results suggest the importance of hypertension, short-term variations in blood pressure, and a sustained nighttime elevation of blood pressure for the pathogenesis of both Binswanger-type and lacunar-type dementia in patients receiving antihypertensive medication.

Isolated systolic hypertension in the elderly: an epidemiologic review

Isolated systolic hypertension (ISH) is usually defined as a systolic blood pressure greater than or equal to 160 mm Hg and diastolic blood pressure less than 90 or 95 mm Hg. Systolic blood pressure has been found to increase with age in most populations studied and thus the prevalence of ISH can be expected to increase with age. ISH is more prevalent in elderly women than in elderly men. Estimates of the prevalence of ISH vary according to its definition and the number of blood pressure measurements. There is evidence that the prevalence of ISH is decreasing. Results of a survey of the prevalence of ISH in 11 countries are presented; the estimates among men aged 60 to 69 years ranged from 1% in Israel to 24% in Norway. Only a prospective standardized survey conducted in several countries will reveal the true prevalence of ISH.

Norepinephrine and forearm vascular resistance responses to tilt and cold pressor test in essential hypertension: effects of aging

Heart rate, blood pressure, forearm vascular resistance (FVR), and catecholamine and renin responses to head-up tilt at 80 degrees and cold pressor test were investigated in 15 hypertensive men aged less than fifty-five (mean 44 +/- 7 years; M +/- SD) and 13 similarly hypertensive men aged more than fifty-five (mean 62 +/- 4 years; M +/- SD). Baseline plasma norepinephrine levels, as well as norepinephrine responses to tilt and cold pressor stress, were similar in the two groups, suggesting a lack of age-related increase in plasma norepinephrine (NE) responses in patients with essential hypertension. Normalized FVR responses (% change) to tilting (28 +/- 21 vs 95 +/- 36; M +/- SE) and cold pressor test (33 +/- 12 vs 64 +/- 21; M +/- SE) were significantly less (p less than 0.01) in older hypertensives. These results, but not the plasma NE responses to reflex sympathetic activation by tilt and cold pressor testing in older hypertensives, suggest an impaired forearm vasoconstriction.

Isolated systolic hypertension in the elderly: pathophysiology and treatment

Isolated systolic hypertension (ISH) is a common clinical finding in the elderly population and appears to be a risk factor for cardiovascular morbidity and mortality. It appears feasible and safe to treat patients with various antihypertensive drugs; however, the morbidity and mortality benefits still need to be determined.

Effect of advancing age on cardiopulmonary baroreceptor function in hypertensive men

Blood pressure, heart rate, forearm vascular resistance, and hormonal responses to graded lower body negative pressure were investigated in 15 hypertensive men younger than 55 years of age (mean age, 44 +/- 2 years) and 13 comparably hypertensive men older than 55 years of age (mean age, 63 +/- 2 years). Baseline forearm vascular resistance was greater in the elderly group compared with the younger hypertensive men. However, forearm vascular resistance responses to selective unloading of low pressure cardiopulmonary baroreceptors were similar in the two groups. This finding suggests that normal vascular responses to the unloading of cardiopulmonary baroreceptors are preserved in subjects with advancing age and mild to moderate hypertension. Baseline plasma norepinephrine levels, as well as norepinephrine responses to lower body negative pressure, were comparable in the two groups. This finding suggests that, unlike normotensive subjects, essential hypertensive subjects do not have an age-related increase in sympathetic nervous system activity.

Overview on atherosclerotic systolic hypertension

Hypertension in older atherosclerotic patients is characterised by a disproportionate elevation of systolic and pulse pressure contrasting with a subnormal diastolic level. Increased systolic pressure is strongly related to the excess of cerebrovascular complications and congestive heart failure observed in these patients. The physiopathological pattern is marked by a strong reduction in compliance of large arteries directly responsible for the predominant high systolic pressure because of the impairment of the buffering function of the arteries on the cardiac pulse wave. Clinical management is directed to the elevation of athero-arteriosclerotic changes of large arteries by means of appropriate non-invasive ultrasonic techniques and specific lowering in systolic pressure. Antihypertensive treatment must specifically decrease systolic pressure without superimposing adverse effects on the generalized and focalized atherosclerotic process. In this respect, new pharmacological agents capable of direct actions on large arteries might be suitable.

Systemic systolic hypertension in the elderly: correlation of hemodynamics, plasma volume, renin, aldosterone, urinary metanephrines and response to thiazide therapy

Twenty-four men, mean age 63 +/- 1.7 years, with systemic systolic hypertension were studied before and after 1 month of therapy with oral hydrochlorothiazide, 50 mg/day. The control mean plasma volume was 2,664 +/- 96 ml, cardiac index 3.9 +/- 0.2 liters/min/m2, stroke volume index 52 +/- 2 ml/beat/m2, systemic vascular resistance 1,351 +/- 80 dynes s cm-5, plasma aldosterone 8.6 +/- 1.0 ng/dl and 24-hour urinary excretion of metanephrines 0.371 +/- 0.044 mg. On renin-sodium profiling in 23 patients, 12 were classified into a normal group and 11 into a low-renin group; none had high renin values. Based on multiple regression analysis, the 24-hour urinary excretion of total metanephrines appeared to be the single most important factor explaining 28% of the variability in systolic blood pressure (BP). After therapy with oral hydrochlorothiazide, the elevated systolic BP decreased (p less than 0.0001) and diastolic BP decreased (p less than 0.005), with concomitant reduction in systemic vascular resistance (p less than 0.03). Patients in both the normal- and low-renin groups had normal plasma volume and responded similarly to thiazide diuretic therapy, without symptomatic side effects.

The Italian Multicenter Study of reversible cerebral ischemic attacks: IV--Blood pressure components and atherosclerotic lesions

Utilizing the initial BP assessment in the 462 patients who entered the Italian Multicenter Study of reversible cerebral ischemia, an analysis of the effect of each BP component in respect of presence, extent and severity of atherosclerotic lesions, as displayed by angiography, was carried out separately for lesions located at either intra- or extracranial level. In a multivariate statistical model, among the following variables: sex, age, systolic BP, diastolic BP, cholesterol and smoking, systolic BP was found the best predictor of extent and severity of atherosclerotic lesions at extracranial level. None of the same variables was predictive of the severity of intracranial atherosclerosis. The results of this clinical study may confirm the indication, coming from physiopathologic observations, of a predominant role of systolic hypertension in the process of maintenance and acceleration of atherosclerosis in the large pre-cerebral arteries.

Hypertension in the elderly

Hypertension in the older population has a serious prognosis and this is true even for isolated systolic hypertension. There is a markedly increased risk of stroke, cardiovascular disease and central nervous system in such patients. The hemodynamics in hypertension of the elderly differs in a number of parameters from hypertension in the younger patient. In addition, drug metabolism is markedly altered by the aging process. This combination of factors requires a selective choice of agents for the management of hypertension in the elderly. The role of various drug modalities and their efficacy is reviewed in this presentation.

Forearm arterial distensibility in systolic hypertension

It is unclear whether the stiffened arterial tree in systolic hypertension is the cause or the effect of the disease. In this study, brachial and radial arterial pulses were sensed by external Pixie transducers and measurements of pulse wave velocity converted to volume distensibility using the Bramwell-Hill equation. Blood pressure was controlled as a variable by repeating the measurements at a variety of transmural arterial pressures. This was accomplished by encasing the forearm in a rigid plastic cylinder within which pressures were varied. Twenty-nine patients with systolic hypertension were compared with 22 age-matched control subjects. At ambient pressures the volume distensibility of patients was lower than that of control subjects (0.10 versus 0.18% delta volume/mm Hg, p less than 0.001) but there was no difference in volume distensibility between the two groups at any comparable transmural pressure. Nineteen patients were treated for 1 month with a thiazide diuretic agent and the studies were then repeated. Systolic and diastolic blood pressure decreased significantly and volume distensibility increased (0.10 to 0.15% delta volume/mm Hg, p less than 0.001) at ambient pressures. But at comparable transmural pressures, volume distensibility was unchanged. It is concluded that, in the forearm, increased arterial stiffness is the result and not the cause of systolic hypertension, but these data cannot exclude increased aortic stiffness as a significant factor. Thiazide diuretic drugs increase forearm arterial compliance by lowering blood pressure without a demonstrable drug effect on this arterial wall.

Aging and hypertension: hemodynamic implications of systolic pressure trends

The progressive rise in systolic pressure throughout life is accepted as a phenomenon of "normative aging," although elevated systolic pressure is established as an independent risk factor for untoward cardiovascular events. An analysis of published data for many thousands of individuals indicates comparable average systolic pressure increments of approximately 20 mm Hg between the ages of 40 and 65 years for both normotensives and hypertensives. In both groups there is a disproportionate rise in systolic pressure, that is, systolic increases more than mean and diastolic pressures. In a young person with a normally elastic arterial system an increase in total peripheral resistance (TPR) produces the same increments in systolic, diastolic, and mean arterial pressures; a decrease in arterial distensibility (AD), on the other hand, increases systolic pressure and decreases diastolic pressure to the same extent, leaving mean pressure unchanged. Thus, the proportion of the systolic pressure rise resulting from increased TPR is equal to the increase in the mean pressure (delta mean); the remainder of the increase (delta systolic minus delta mean) is caused by the only other variable that could account for an additional increase in systolic pressure with advancing age, a decrease in AD. Application of this formulation to published blood pressure data shows that in normotensives the ratio of the contribution toward rising systolic pressure of reduced AD to increased TPR is 1:1 between the ages of 40 and 65 years, whereas in hypertensives it is 2:1. Thus, the natural history of essential hypertension, once established, is one of accelerated arterial stiffening, a mechanism that would contribute importantly to the increasing prevalence of "systolic hypertension" with advancing age.

Geriatric hypertension

Hypertension in the elderly is a frequent occurrence and is associated with an increase in cardiovascular complications. Therapeutic drug intervention in diastolic-systolic hypertension is both safe and effective in decreasing cardiovascular morbidity and mortality. Convincing evidence supporting the value of therapeutic intervention in isolated systolic hypertension is not yet available. At present, selection of specific antihypertensive drugs remains empirical because of insufficient controlled trials in elderly hypertensives. Antihypertensive agents should be initiated in smaller dosages and titrated upward slowly with particular care in avoiding orthostatic hypotension. Above all, lifestyle modification should be kept to a minimum and special attention should be given to the patient's quality of life while on drug treatment.

Adrenergic activity in systolic hypertension

Basal hemodynamics and plasma catecholamines were measured in 10 patients with systolic hypertension, 7 males and 3 females, aged 38-69 years (Group 1), and in 10 patients with systolic and diastolic hypertension, 7 males and 3 females, aged 40-65 years (Group 2); the same measurements were repeated after acute pharmacological alpha and beta-blockade with Labetalol, 100 mg iv, or Propranolol, 10 mg iv, plus Phentolamine, 10 mg iv. In patients of Group 1 plasma noradrenaline was inversely related to systolic arterial pressure and to stroke index and was directly related to heart rate. In patients of Group 2 plasma noradrenaline was directly related to systolic arterial pressure. After acute alpha and beta-blockade the degree of reduction of systolic arterial pressure was directly related to basal plasma noradrenaline in both groups; systolic arterial pressure was reduced to normotensive levels in 5 patients of Group 1 who had high basal plasma noradrenaline values. These results confirm some of our previous findings and suggest that in some patients with systolic hypertension adrenergic activity is increased and may have a significant role in maintaining high blood pressure values.

Aortic rigidity and plasma catecholamines in essential hypertensive patients

Aortic rigidity, plasma noradrenaline and adrenaline, and hemodynamic parameters were measured in 48 essential hypertensive patients, 25 younger than 45 (Group I) and 23 of 45 years and over (Group II). Aortic rigidity was determined by the ratio of pulse pressure over stroke volume. Aortic rigidity and hemodynamic parameters were also determined after combined alpha-beta receptor blockade induced by Labetalol (mg 100 IV) or by Propranolol (mg 10 IV) plus Phentolamine (mg 10 IV). The aortic rigidity index was significantly higher in Group II, systolic arterial pressure being significantly higher. All other data, including plasma noradrenaline and adrenaline, were not significantly different in the two groups. In Group II a significant correlation (r = 0.62) was noted between aortic rigidity indexes and plasma noradrenaline values. The alpha-beta receptor blockade induced a decrease of aortic rigidity particularly in Group II, owing to a more marked decrease of systolic arterial pressure. A highly significant correlation was noted in Group II between the changes in aortic rigidity index and the basal plasma noradrenaline levels (r = 0.81). Therefore, the aortic rigidity in essential hypertensive patients older than 45 is influenced by the sympathetic nervous system activity, as judged by plasma noradrenaline levels. This influence seems related to an increase with age of aortic responsiveness to sympathetic stimulation.

Raised plasma catecholamines in old and young patients with disproportionate systolic hypertension

Sympathetic nerve tonicity was assessed in hypertensives with either proportionate or disproportionate elevation of systolic blood pressure: patients were segregated into two groups, age less than 40 years and age 40 years and greater. Plasma catecholamines of sixty patients with proportionate hypertension and thirty five with disproportionate hypertension were compared with those of sixty one age matched normotensive volunteers. Disproportionate patients were younger than proportionate hypertensives in the age group less than 40 years (p less than .01) and were older than proportionate in the 40 years and older group (p less than .01). The youngest and oldest patients with disproportionate systolic hypertension tended to have normal diastolic blood pressure. Total plasma catecholamines were increased in both groups of hypertensives, whether young or old. However, only values in male hypertensives were increased significantly when compared with normotensives (p less than .01). Enhanced sympathetic nervous system tonicity appears to be an important factor in the cause and maintenance of both proportionate and disproportionate systolic hypertension.

Differential antihypertensive effect of acebutolol and hydrochlorothiazide/amiloride hydrochloride combination on elevated exercise blood pressures in hypertensive patients

The blood presure abilities of the beta receptor antagonist acebutolol and the fixed diuretic combination of hydrochlorothiazide/amiloride hydrochloride to reduce exercise-induced increases in blood presure durng and after standardized ergometric work were compared in a within-patient study of patients with uncomplicated essential hypertension. Both drugs results in a significant (p < 0.01) and almost identical reduction in blood pressure at rest. However, blood pressure during exercise was significantly lower (p < 0.001) with 500 mg of acebutolol than with 50 mg of hydrochlorothiazide and 5 mg of amiloride. This differential effect of the drugs might be of clinical importance because hypertensive patients are particularly endangered by disproportionately high increases in blood pressure during physical activity that is equal to the applied ergometric work loads. From these findings it is concluded that (1) beta-adrenoreceptor blocking agents are the drugs of first choice in the treatment of mild to moderate arterial hypertension, and (2) diuretic drugs potentiate the antihypertensive effect of beta blocking agents.

Behavioral medicine approaches to hypertension: an integrative analysis of theory and research

This article compares behavioral and biological approaches to hypertension, highlights some of the practical, semantic, and theoretical issues involved, and attempts a constructive, behavioral medicine integration of these approaches. The major behavioral approaches to hypertension are described, with a focus on their conceptual limitations as stimulants to research into psychobiological mechanisms. A biobehavioral systems analysis of hypertension is outlined, emphasizing the role of the central nervous system as a common pathway relating environmental and behavioral factors to cardiovascular regulatory dynamics and disease. Schwartz's concept of blood pressure disregulation is discussed, by which behavioral "feedback loops" may be included in the pathogenesis of homeostatic disorders. A detailed discussion of concepts underlying the clinical pharmacological approach to hypertension is provided; parallels are drawn between the conceptual framework and the theoretical and practical questions facing behavioral researchers concerned with hypertension. Synergistic interactive effects of drug and behavioral treatments are proposed. A biobehavioral overview, which links pressor and depressor stimulus patterns to both pathogenesis and therapy, can serve to integrate the previous biobehavioral systems analysis, the conceptual framework of clinical pharmacology, and the notion of biobehavioral disregulation of blood pressure. Implications for future behavioral medicine research in hypertension are provided.