Systemic and regional hemodynamics in low, normal and high cardiac output borderline hypertension

Individuals with hypertension have lower plasma volume regardless of weight status

Increased plasma volume is often reported as a cause or symptom of hypertension in individuals with obesity. However, these individuals are often compared to normal weight normotensive individuals. Since higher plasma volumes have been reported in larger individuals, it is possible that plasma volume is actually lower in obese hypertensive individuals compared to normotensive obese individuals. This may be important for better understanding the clinical manifestation of hypertension between weight categories. National Health and Nutritional Examination Survey (cycles 1999-2018) data were used to examine the relationship between plasma (derived from the Straus formula), blood pressure (measured with an automated device) and body mass index. We observed an inverse relationship between estimated plasma volume and systolic (B = -1.68 (95% CI: -2.06, -1.30) mmHg), p < 0.0001), diastolic (B = -3.35 (95% CI: -3.61, -3.08) mmHg) p < 0.0001), and mean arterial pressure (B = -2.79 (95% CI: -3.05, -2.53) mmHg) p < 0.0001). The relationship between estimated plasma volume and diastolic blood pressure (interaction term: B = -0.069 (-0.10, -0.03), p < 0.0001) did depend on BMI. The "normal weight" group had the lowest slope and this slope was significantly different from the "obese" (B = -1.47 (95% CI: -1.88, -1.07)) and "overweight" (B = -1.11 (-1.55, -0.67)) groups. Plasma volume is lower in hypertensive individuals regardless of weight status, but this relationship is more pronounced among obese individuals.

Presence of Kidney Disease as an Outcome Predictor in Patients with Pulmonary Arterial Hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) may lead to right heart failure and subsequently alter glomerular filtration rates (GFR). Chronic kidney disease (CKD, GFR <60 mL/min/1.73 m2) may also adversely affect PAH prognosis. This study aimed to assess how right heart hemodynamics was associated with reduced estimated GFR (eGFR) and the association of CKD with survival in PAH patients.

METHODS

In a prospective PAH cohort (2003-2012), invasive hemodynamics and eGFR were collected at diagnosis (179 patients) and during follow-up (159 patients). The prevalence of CKD was assessed at PAH diagnosis. Variables, including hemodynamics, associated with reduced eGFR at diagnosis and during follow-up were tested in multivariate analysis. The association of CKD with survival was evaluated using a multivariate Cox regression model.

RESULTS

At diagnosis, mean age was 60.4 ± 16.5 years, mean pulmonary arterial pressure was 43 ± 12 mm Hg, and eGFR was 74.4 ± 26.4 mL/min/1.73 m2. CKD was observed in 52 incident patients (29%). Independent determinants of reduced eGFR at diagnosis were age, systemic hypertension, and decreased cardiac index. Independent determinants of reduced eGFR during follow-up were age, female gender, PAH etiology, systemic hypertension, decreased cardiac index, and increased right atrial pressure. Age ≥60 years, female gender, NYHA 4, and CKD at diagnosis were independently associated with decreased survival. The adjusted hazards ratio for death associated with CKD was 1.81 (95% confidence interval [1.01-3.25]).

CONCLUSION

CKD is frequent at PAH diagnosis and is independently associated with increased mortality. Right heart failure may induce renal hypoperfusion and congestion, and is associated with eGFR decrease.

Aortic Blood Flow Reversal Determines Renal Function

Aortic stiffness determines the glomerular filtration rate (GFR) and predicts the progressive decline of the GFR. However, the underlying pathophysiological mechanism remains obscure. Recent evidence has shown a close link between aortic stiffness and the bidirectional (systolic forward and early diastolic reverse) flow characteristics. We hypothesized that the aortic stiffening–induced renal dysfunction is attributable to altered central flow dynamics. In 222 patients with hypertension, Doppler velocity waveforms were recorded at the proximal descending aorta to calculate the reverse/forward flow ratio. Tonometric waveforms were recorded to measure the carotid-femoral (aortic) and carotid-radial (peripheral) pulse wave velocities, to estimate the aortic pressure from the radial waveforms, and to compute the aortic characteristic impedance. In addition, renal hemodynamics was evaluated by duplex ultrasound. The estimated GFR was inversely correlated with the aortic pulse wave velocity, reverse/forward flow ratio, pulse pressure, and characteristic impedance, whereas it was not correlated with the peripheral pulse wave velocity or mean arterial pressure. The association between aortic pulse wave velocity and estimated GFR was independent of age, diabetes mellitus, hypercholesterolemia, and antihypertensive medication. However, further adjustment for the aortic reverse/forward flow ratio and pulse pressure substantially weakened this association, and instead, the reverse/forward flow ratio emerged as the strongest determinant of estimated GFR ( P =0.001). A higher aortic reverse/forward flow ratio was also associated with lower intrarenal forward flow velocities. These results suggest that an increase in aortic flow reversal (ie, retrograde flow from the descending thoracic aorta toward the aortic arch), caused by aortic stiffening and impedance mismatch, reduces antegrade flow into the kidney and thereby deteriorates renal function.

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.

Treatment of resistant hypertension

Although the true prevalence of resistant hypertension is not known, it is likely that this condition will become increasingly common, driven by an aging population, obesity, nonadherence trends, and effects of target-organ disease. Current approaches focus on two goals: evaluation and correction of contributing causes, then selection of an effective drug regimen. Lifestyle factors contribute to resistance, particularly high sodium intake and weight gain. Secondary causes should be considered and corrected if feasible. Recent efforts have focused on the development of clinical pathways to guide treatment, based on plasma renin activity, aldosterone production, or hemodynamic measurements. The components of drug combinations beyond the second agent remain empiric. Although volume expansion plays a key role in drug resistance, clinical assessment of volume status is often difficult, frustrating efforts to achieve blood pressure control. Determination of the most effective approaches will require clinical trials using combination therapy.

Abnormal impedance cardiography predicts symptom severity in chronic fatigue syndrome

BACKGROUND

Findings indicative of a problem with circulation have been reported in patients with chronic fatigue syndrome (CFS). We examined this possibility by measuring the patient's cardiac output and assessing its relation to presenting symptoms.

METHODS

Impedance cardiography and symptom data were collected from 38 patients with CFS grouped into cases with severe (n = 18) and less severe (n = 20) illness and compared with those from 27 matched, sedentary control subjects.

RESULTS

The patients with severe CFS had significantly lower stroke volume and cardiac output than the controls and less ill patients. Postexertional fatigue and flu-like symptoms of infection differentiated the patients with severe CFS from those with less severe CFS (88.5% concordance) and were predictive (R2 = 0.46, P < 0.0002) of lower cardiac output. In contrast, neuropsychiatric symptoms showed no specific association with cardiac output.

CONCLUSIONS

These results provide a preliminary indication of reduced circulation in patients with severe CFS. Further research is needed to confirm this finding and to define its clinical implications and pathogenetic mechanisms.

Excess catecholamine syndrome. Pathophysiology and therapy

In addition to genetic factors, lifestyle has a predominant influence on primary hypertension and noninsulin-dependent diabetic mellitus (NIDDM). We initiated studies using radiotelemetry for characterizing molecular events linked with excess calorie intake and psychologic stress. An increased calorie intake was associated with raised (p < 0.05) systolic and diastolic blood pressure as well as heart rate independent of day-night cycle. Sympathetic activity was in excess when related to the unchanged motility. The hyperkinetic hypertension is expected to result in adverse remodeling of resistance vessels and to aggravate insulin resistance. To examine adverse effects of psychological stress, rats were subjected to intermittent food pellet feeding. Urinary catecholamines and cardiac norepinephrine stores were increased (p < 0.05). The depressed (p < 0.05) rate of Ca2+ uptake of sarcoplasmic reticulum is expected to contribute to cellular Ca2+ overload. These lifestyle influences strengthen the notion of an excess catecholamine syndrome which requires selective reduction of sympathetic outflow of the brain by I1-receptor agonists.

Consequences of the increased autonomic nervous drive in hypertension, heart failure and diabetes

It is estimated that 40 million people in the USA have hypertension, 14 million are diabetic and 4 million suffer congestive heart failure. Since all three conditions are age-related, as the longevity in industrialized societies continues to improve, the overall burden of congestive heart failure, hypertension and diabetes will increase. These major diseases of civilization are characteristically associated with an increased autonomic cardiovascular drive. In our terminology the output that emanates from the central nervous system via sympathetic and parasympathetic efferents is referred to as "tone". The overall "drive" depends on the balance between inhibitory (parasympathetic) and excitatory (sympathetic) tone and the organ's responsiveness to that tone. The responsiveness, in turn, depends on the receptors' properties as well as on the intrinsic functional or anatomic properties of the responding organs. These components can change independently. For example, in the course of hypertension the alpha-adrenergic responsiveness increases whereas the beta-adrenergic responses are down-regulated. Another example is: plasma noradrenaline and sympathetic tone are increased in elderly subjects but their circulation does not show any tell-tale response of increased sympathetic tone, presumably because the responses to sympathetic tone decrease with aging. These complex interactions between the autonomic tone and organ responsiveness determine to a great extent the overall clinical impact of the autonomic abnormality in hypertension, non-insulin-dependent diabetes mellitus and in congestive heart failure. The major thesis of this review is that, whether primary or secondary, whether easily discerned or hidden, an enhanced autonomic drive, independent of the underlying condition, greatly increases the risk of poor cardiovascular outcomes. It follows that targeting the underlying autonomic imbalance in congestive heart failure, hypertension and diabetes may not only be pathophysiologically sound but such an approach may also lead to better outcomes.

Pathophysiologic and prognostic implications of measuring arterial compliance in hypertensive disease

Structural alterations of the arterial wall precede atherosclerosis and cardiovascular events. Endothelial dysfunction appears to be the earliest marker for this structural change that makes the vasculature sensitive to the adverse effects of pressure, lipids, diabetes, smoking and other so-called risk factors. Reduced arterial compliance or elasticity provides an index to the structural abnormalities associated with aging and disease states. Preliminary studies suggest that an alteration in pulsewave oscillations induced at small artery branch points serves as a guide to endothelial dysfunction and reduced nitric oxide bioactivity. Additional studies are urgently needed to document the usefulness of clinical measurement of arterial compliance as a marker for the vascular abnormality that leads to cardiovascular disease and as a guide to efficacy of therapeutic interventions.

Decreased regional blood flow in patients with acromegaly

BACKGROUND AND AIMS

One-third of acromegalic patients have hypertension. Acromegaly is also associated with intrinsic cardiac abnormalities known collectively as a hyperkinetic heart syndrome, which is characterized by an increased cardiac index and decreased systemic vascular resistance. As a result, blood flow should be increased in the regional vascular beds of acromegalic patients. The aim of the study was to measure, using direct methods, blood flow and vascular resistance at the level of the brachial artery in acromegalic patients with a confirmed hyperkinetic heart syndrome.

PATIENTS AND CONTROLS

Twelve patients with active acromegaly (five females, seven males; mean (+/- SD) age, 43 +/- 10 years) were studied. Twelve age- and sex-matched normal subjects served as controls.

METHODS

Right heart catheterization was used to measure the cardiac index and stroke volume and to calculate systemic vascular resistance in the acromegalic patients. Brachial haemodynamics were evaluated with a two-dimensional pulsed Doppler system (double transducer probe and range-gated time system of reception). The mean diameter of the brachial artery and mean blood velocity were measured and used to calculate mean blood flow. Vascular resistance was calculated in the brachial artery as the mean arterial pressure/blood flow ratio.

RESULTS

Age, body weight, height, body surface area and heart rate were similar in the acromegalic patients and controls, while mean arterial pressure was higher in patients. The cardiac index and stroke volume were increased in the acromegalic patients, at 4.08 +/- 0.47 (mean +/- SD) l/min/m2 body surface area and 116.7 +/- 19.4 ml, respectively, while systemic vascular resistance was low (12.5 +/- 2.1 U). Brachial artery diameter was similar in the patients and controls. Brachial artery mean blood velocity (P < 0.01) and mean blood flow (P < 0.05) were lower in the patients than in the controls (3.35 +/- 1.26 vs. 5.12 +/- 1.74 cm/s, and 16.4 +/- 9.4 vs. 25.6 +/- 11.6 ml/min/m2, respectively). The higher mean arterial pressure and lower mean blood flow resulted in higher forearm vascular resistance in the patients than in the controls (132 +/- 61 vs. 83.8 +/- 47 mmHg/ml/s/m2, respectively, P < 0.01).

CONCLUSION

While cardiac output is increased and systemic vascular resistance is decreased in active acromegaly, direct measurement of brachial artery haemodynamics showed lower regional blood flow and increased local resistance relative to healthy controls. These results suggest a heterogeneous distribution of cardiac output in acromegaly.

Nephroprotective effect of antihypertensive drugs in essential hypertension

BACKGROUND

Effective antihypertensive treatment has prevented target-organ involvement in hypertension, markedly reducing morbidity and mortality from strokes, coronary heart disease, cardiac failure, and hypertensive emergencies. However, the incidence of hypertension-related end-stage renal disease continues to increase, suggesting that therapeutic reduction in arterial pressure by itself is not sufficient to prevent the development of hypertensive renal failure.

OBJECTIVE

To examine experimental and clinical data concerning the protective effect of reduction of arterial pressure on the progression of hypertension-related renal disease, and the evidence indicating that some antihypertensive agents may afford more nephroprotection, over and above that attributable to reduction of arterial pressure.

RESULTS

Results of numerous studies clearly indicate that adequate control of arterial pressure, irrespective of the antihypertensive agent used, slowed the progression of renal disease. Results of some studies suggest that lowering arterial pressure below the level that is usually considered adequate has an additional beneficial effect by slowing the progression of renal injury.

CONCLUSION

Results of a number of studies evaluating nephroprotective effects of various drugs and regimens have indicated that certain agents, most notably angiotensin converting enzyme inhibitors and their combination with calcium antagonists, afford more protection than do others at similar levels of reduction of arterial pressure. Results of still other studies suggest that certain agents that exert greater nephroprotection are more efficient at controlling arterial pressure. Therefore, further data are needed before any final conclusion can be drawn. However, it is clear that, in order to establish nephroprotection in patients with essential hypertension, the problem should not be further complicated by additional comorbid diseases such as diabetes mellitus.

Comparison of early target organ damage between blacks and whites with mild systemic arterial hypertension

As greater mortality and morbidity from target organ damage in arterial hypertension have been reported for black than for white hypertensives, we examined in a matched-pair analysis whether race per se affected markers of early target organ damage at similar levels of blood pressure. After controlling for the confounding factors such as age, sex, weight, and arterial pressure that interact with hypertension-related target organ damage, no racial disparities could be detected between matched black and white hypertensive patients.

Cardiovascular effects of a trandolapril/verapamil combination in patients with mild to moderate essential hypertension

The cardiovascular effects of a combination of trandolapril and verapamil were evaluated in 14 patients with mild to moderate essential hypertension. This combination therapy decreased arterial pressure mainly through a decrease in total peripheral resistance without causing an increase in heart rate or cardiac output: left ventricular mass was significantly reduced, cardiac systolic function improved, and plasma volume and renal blood flow remained unchanged.

Arterial and venous compliance in obese and nonobese subjects

Arterial compliance and central blood volume were evaluated in obese and nonobese patients with and without hypertension. Arterial compliance was lower in the hypertensive group, although obese subjects, regardless of their blood pressure, had higher arterial compliance. The ratio of central blood volume to total blood volume was highest in hypertensive patients, whether obese or lean, indicating increased venoconstriction.

Reduction in left ventricular mass in patients with systemic hypertension treated with enalapril, lisinopril, or fosenopril

There are still conflicting data as to whether reduction in LV mass is beneficial. In the present study, no deterioration in LV systolic function occurred in patients in whom regression of LV mass was achieved. Impairment in LV compliance has been shown in hypertensive patients, even in the presence of preserved systolic function and normal LV mass. In our study, improvement in diastolic function was observed only in patients whose LV mass decreased, and it was related to reduction in mass and not to a decrease in mean arterial pressure. Therefore, we suggest that because diastolic function is the first activity to deteriorate in hypertensive patients, it may be the first activity to improve, and this improvement may be related to reduction in LV mass with ACE inhibitors.

Investigative Concerns in Demonstrating Reduced Risk From Reversing Left Ventricular Hypertrophy

BACKGROUND: To demonstrate reduced risk from reversing left ventricular hypertrophy (LVH) in hypertension, one must show that it is independent of blood pressure reduction. METHODS AND RESULTS: A feasibility study was conducted with 15 patients. The study employed 48-hour Holter recording, exercise treadmill (for ST-segment changes) and, as necessary, thallium scintigraphy and coronary angiography. All patients were treated for 3 months with quinapril (10 mg) and demonstrated decreased mean arterial pressure (125 +/- 3.1 vs 103 +/- 1.9 mmHg; P <.01) and left ventricular mass index (125 +/- 6.4 vs 104 +/- 4.9; P <.02) with preserved left ventricular function. There were no significant changes in these patients with moderate LVH in the incidence of arrhythmias; however, 4 of the 15 patients developed ST-segment changes prior to LVH reversal, and these changes did not recur in 3 patients following reversal of LVH or when pressure was allowed to rise. CONCLUSIONS: Ischemic changes, rather than development of arrhythmias, may be of greater value in demonstrating risk reduction with LVH reversal. Moreover, these preliminary data suggest pitfalls in demonstrating risk reduction after LVH reversal, indicating that more sensitive and adequate techniques are necessary to show risk reduction from LVH.

Central blood volume: a determinant of early cardiac adaptation in arterial hypertension?

OBJECTIVES

This study was undertaken to assess the influence of the fluid volume state on cardiac adaptation to hypertension.

BACKGROUND

Left ventricular hypertrophy is an important predictor of hypertensive complications. We analyzed volume status and its impact on cardiac structural changes in early hypertension.

METHODS

In 33 normotensive subjects, 40 patients with borderline hypertension and 63 patients with established essential hypertension, mean arterial pressure was measured invasively; total blood volume was measured by iodine-125-labeled plasma albumin and hematocrit; central blood volume by indocyanine green dye dilution curve; and diastolic diameter and left ventricular mass by two-dimensional-guided M-mode echocardiography.

RESULTS

Central blood volume was approximately 20% higher in patients with stage I borderline hypertension than in normotensive subjects ([mean +/- SD] 3,001 +/- 663 vs. 2,493 +/- 542 ml, p < 0.05), whereas total blood volume was similar in all three groups. This shift in intravascular volume toward the cardiopulmonary circulation was accompanied by a significant increase in diastolic diameter (5.29 +/- 0.80 vs. 4.86 +/- 0.77 cm, p < 0.05) and in left ventricular mass (239.4 +/- 90.6 vs. 183.5 +/- 68.8 g, p < 0.05) in patients with borderline hypertension compared with subjects with normotension. In patients with established essential hypertension, volume status of stroke volume and diastolic dimension returned to normal values, whereas left ventricular mass increased further.

CONCLUSIONS

We conclude that the early phase of hypertension is characterized by centripetal distribution of intravascular volume, leading to an increased preload to the left ventricle. This change in volume status appears to be related to cardiac structural adaptation to an increase in arterial pressure.

Stimulus dimensions of the cold pressor test and the associated patterns of cardiovascular response

Hemodynamics of the cold pressor response in relation to its pain and nonpain stimulus components were investigated in normotensive college men using the foot and forehead cold pressor tasks. Mechanisms of pain- and non-pain-related increases in blood pressure were analyzed as residual effects of concurrent changes in total peripheral resistance and cardiac output. The identified partial relationships suggested that the response pattern associated with pain included positive change both in cardiac output and in total peripheral resistance, whereas the nonpain-related response was limited to an increase in total peripheral resistance. Analyses of individual differences in cardiovascular responses to pain further indicated that pain-related increments in blood pressure were mediated by a steeper rise in total peripheral resistance, an increase in heart rate, and an apparent increase in preload. At baseline, high reactors to pain manifested relatively elevated total peripheral resistance, diminished cardiac output, and an indication of a reduced inotropic state, suggesting that altered basal homeostasis may discriminate normotensive individuals displaying heightened cardiovascular reactivity to aversive cold stimulation.

Abnormalities of autonomic nervous control in human hypertension

The pathophysiology of various stages of hypertension is different. In early hyperkinetic borderline hypertension, the sympathetic drive to the heart and blood vessels is increased while the parasympathetic cardiac inhibition is decreased. The elevated cardiac output, vascular resistance, and blood pressure at that stage can be fully normalized by autonomic blockade. As hypertension advances, a hyperkinetic circulation is less evident, since beta-adrenergic responsiveness and cardiac compliance tend to decrease. Simultaneously hypertrophy of the resistance vessels increases the baseline vascular resistance and the vessels' responsiveness to constrictive stimuli. Eventually a picture of a normal cardiac output/high vascular resistance typical for established essential hypertension emerges. As the blood vessels become hyperreactive, the same degree of vasoconstriction/blood pressure elevation can be achieved with less sympathetic tone. In that phase the sympathetic overactivity is less evident, as the brain resets itself to maintain the same blood pressure elevation with a small amount of sympathetic discharge. While sympathetic overactivity may be less evident in established hypertension, it remains an important pathophysiologic factor, not only for the maintenance of blood pressure, but also for a number of other abnormalities in hypertension. Hypertension is intimately associated with higher levels of pressure-unrelated risk for development of atherosclerosis: dyslipidemia, overweight, and hyperinsulinemia. Furthermore, a number of factors in hypertension favor a poorer outcome from coronary heart disease. These pressure-independent factors increase the risk of coronary thrombosis, arrhythmic deaths, and coronary spasms. Sympathetic overreactivity appears to be crucially implicated in the evolution of this added coronary risk in hypertension. Understanding the pathophysiology of coronary risk and its relationship to sympathetic overreactivity in hypertension is helpful in seeking further improvements in clinical practice. At present antihypertensive treatment is less efficacious in reducing coronary events in hypertension than would be expected. Judicious use of appropriate drugs promises to further improve the efficacy of antihypertensive treatment in those patients who, in addition to high blood pressure, also have other associated risk factors.

Accelerated decline in renal perfusion with aging in essential hypertension

The present cross-sectional study was designed to assess the effect of the severity of hypertensive cardiovascular disease and age on renal hemodynamics. In a homogeneous population of 157 white men (aged 15 to 87 years), we assessed renal and systemic hemodynamics by measuring mean arterial pressure invasively, renal blood flow by 131I-para-aminohippuric acid clearance, and cardiac output by the indocyanine dye dilution technique. Stepwise multiple regression analysis revealed the following independent determinants of renal blood flow: age (beta = -.42, P < .001), height (beta = +.14, P < .03), mean arterial pressure (beta = -.15, P < .02), and cardiac output (beta = +.19, P < .008). Renal blood flow corrected for height correlated inversely with age in all three groups. However, the renal fraction of cardiac output did not correlate with age in borderline hypertension (r = .17, P = NS) and in normotension (r = .12, P = NS), suggesting a parallel decline in renal blood flow and cardiac output with aging. In contrast, in established hypertension, the renal fraction of cardiac output was closely linked to age (r = .52, P < .001) and significantly steeper (P < .01) than in normotension or borderline hypertension. We conclude that unlike in normotensive subjects or patients with borderline hypertension, patients with established hypertension have an accelerated decline in renal perfusion with aging, reflecting selective functional or structural changes or both in the renal vascular bed.

Are renal hemodynamics a key factor in the development and maintenance of arterial hypertension in humans?

The kidney plays a key role in the control of body fluids and blood pressure. Evidence has shown that impairment of renal function can lead to the development of arterial hypertension. The regulation of renal blood flow appears to be a key element in the pathophysiology of the hypertensive process, because multiple evidence suggests the existence of a functional enhancement of renal vascular tone in this disorder. The existence of renal vasoconstriction and of an inherited defect in the regulation of renal blood flow has been proposed in the prehypertensive stage. The mechanisms responsible for this alteration include a lack of modulation of the renal vasculature to angiotensin II, increased sympathetic activity, or suppressed renal dopaminergic activity. Established hypertension is characterized by elevated renal vascular resistance, decreased renal blood flow, sustained glomerular filtration rate, and increased filtration fraction. The increase in renal vascular resistance is initially due to elevations in renal vascular tone and is reversible, whereas later it becomes irreversible because of structural changes involved in nephrosclerosis. Antihypertensive drugs are able to decrease blood pressure and to prevent the development of further renal vascular damage independently of variable effects on renal hemodynamics.

Disparate cardiovascular response to stress tests during isradipine and fosinopril therapy

Optimal antihypertensive therapy should control blood pressure at rest and during stress while preserving the physiologic hemodynamic response. In patients with mild to moderate hypertension, the hemodynamic profile and catecholamine response at rest, during isometric, mental, and orthostatic stresses were compared before and 12 weeks after angiotensin-converting enzyme inhibition or calcium channel blockade. Antihypertensive therapy was titrated either with the angiotensin-converting enzyme inhibitor fosinopril (10 to 40 mg; n = 9) or with the calcium antagonist isradipine (5 to 20 mg; n = 10) until diastolic blood pressure < 90 mm Hg was achieved. Groups were comparable in race, sex, body mass index, pretreatment mean arterial pressure and response to isometric stress (25% increase in mean arterial pressure) before treatment. At rest, total peripheral resistance was reduced to the same extent (18%) in both groups. After fosinopril, the percent increase in stroke volume was higher and heart rate lower than with isradipine. During isometric stress, the percent increase in mean arterial pressure and cardiac output was higher, with isradipine (p < 0.05) reaching pretreatment levels. Plasma catecholamines were also higher with isradipine (p < 0.05), increasing by 100% with plasma norepinephrine compared with 16% before treatment. During orthostatic stress significant reductions in mean arterial pressure and stroke volume were observed after isradipine but not after fosinopril. Neither medication significantly modified the response to mental stress. Our data suggest that despite a comparable reduction in total peripheral resistance at rest, fosinopril preserves a more physiologic hemodynamic response to isometric and orthostatic stress than isradipine.(ABSTRACT TRUNCATED AT 250 WORDS)

Distribution and correlates of creatinine clearance in children and adolescents with blood pressure elevation

The kidney has been implicated as both an etiologic factor and as a target organ in patients with essential hypertension. Renal function has not been studied extensively in children and adolescents with essential hypertension. Eighty-eight subjects, aged 6 to 23 years, with blood pressure persistently above the 90th percentile for age were studied. Creatinine clearance was determined from a single 24-hour urine collection. The mean creatinine clearance was 129.3 +/- 55.3 ml/min per 1.73 m2. Multiple regression analysis was used to investigate potential correlates of creatinine clearance. Because creatinine clearance was not normally distributed, the logarithm of creatinine clearance was used as the dependent variable. Body mass index, resting heart rate, and basal supine plasma renin activity were significant direct independent correlates. Peripheral vascular resistance at maximal exercise was an inverse correlate of the logarithm of creatinine clearance. These findings are consistent with previous studies of adults and may provide the basis for strategies to identify young patients with essential hypertension who are at risk for the development of renal dysfunction.

Hemodynamic alterations and urinary albumin excretion in patients with essential hypertension

Salt-sensitive animals as well as patients with essential hypertension appear to have a greater propensity to develop renal disease as a consequence of hypertension. They also manifest an abnormal renal hemodynamic adaptation to changes in dietary sodium intake and blood pressure. This suggests that the two may be related. Some patients with essential hypertension manifest an increase in urinary albumin excretion (UAE). It is uncertain whether this is more common in salt-sensitive patients and whether it represents a marker for progressive renal disease. The effect of antihypertensive agents on UAE varies substantially depending on the agent used, and it is not necessarily related to the antihypertensive action. Whether antihypertensive agents that more effectively reduce UAE may also result in greater renal protective effects remains to be established.

Does obesity influence early target organ damage in hypertensive patients?

BACKGROUND

Various prospective studies have found that lean hypertensive patients have greater cardiovascular morbidity and mortality than obese hypertensive subjects. It was therefore hypothesized that hypertension is more benign when associated with obesity. In the present study, we evaluated effects of obesity on early target organ damage in patients with essential hypertension.

METHODS AND RESULTS

In a total of 207 subjects, systemic and renal hemodynamics as well as left ventricular structure and function were assessed by measuring cardiac output (indocyanine green dye dilution), renal blood flow (clearance of 131I paraimmunohippuric acid), and mean arterial pressure (invasively) and by two-dimensionally guided M-mode echocardiographic findings. Systemic and renal vascular resistance, compliance of the large arteries evaluated by the stroke volume/pulse pressure index, and left ventricular mass served as parameters for early target organ damage. All individuals were categorized into four groups: lean and obese normotensive as well as lean and obese hypertensive subjects. In obese hypertensive patients, total peripheral resistance was significantly lower and stroke volume/pulse pressure index was higher than in the lean hypertensive group, almost reaching values of normotensive control subjects. No effect of obesity on the renal circulation was noted, whereas in hypertension, renal vascular resistance was elevated. The degree of left ventricular hypertrophy was more pronounced in the hypertensive groups than in their normotensive counterparts and progressively increased with obesity. Nevertheless, in obese hypertensive patients, left ventricular function, as measured by fractional fiber shortening and velocity of circumferential fiber shortening, was maintained despite the fact that the heart had been exposed to the double burden of an increased preload (obesity) and afterload (hypertension).

CONCLUSIONS

Obesity had a disparate effect on target organs in hypertension. At rest, obesity seemed to mitigate cardiovascular changes in the systemic vascular bed caused by hypertension. However, no such mitigation was observed in the renal vasculature, and left ventricular hypertrophy was even exacerbated by the presence of obesity. Our findings in part negate the concept that obesity is able to exert a protective effect on early target organ damage in hypertensive patients and, in particular, on the heart.

Stress response pattern in obesity and systemic hypertension

Under resting conditions obese hypertensive patients have been described as having a greater cardiac output and lower total peripheral resistance than lean hypertensive patients. To evaluate the hemodynamic patterns under stress conditions, we determined the hemodynamic response to mental stress (first study) and during isometric exercise (second study) in hypertensive patients with a body mass index > 27 kg/m2 (obese) and < 27 kg/m2 (lean). The cohort exposed to mental stress comprised 54 white male patients (30 were lean, 24 were obese) with untreated stage I or II essential hypertension according to the World Health Organization. Obese subjects responded with a higher increase in total peripheral resistance (p < 0.02) and lower increases in heart rate (p < 0.01), cardiac output (p < 0.01) and stroke volume (p < 0.02) when compared with their lean counterparts. This was independent of any differences in chemical or baseline hemodynamic characteristics at rest. The cohort exposed to isometric stress consisted of 57 patients (30 were lean, 27 were obese) with World Health Organization stage I or II essential hypertension. Obese subjects responded with exaggerated increases in systolic (p < 0.04) and diastolic (p < 0.01) pressures, and heart rate (p < 0.04) when compared with lean patients. Body mass index emerged as an independent determinant of the increase in systolic (r = 0.03) and diastolic (r = 0.01) pressure as well as of heart rate (r = 0.03). These results indicate that obese hypertensive patients respond to (1) mental stress with vasoconstriction instead of the expected vasodilation, and to (2) isometric stress with an exaggerated increase in arterial pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamic and metabolic effects of intravenous clentiazem in hypertensive patients

To determine the hemodynamic and certain metabolic effects of clentiazem, a diltiazem congener, 10 untreated essential hypertensive patients were given the calcium antagonist in 3 successive doses totaling 1.0 mg/kg intravenously. Mean arterial pressure and total peripheral resistance progressively declined from 121 +/- 3 mm Hg and 47 +/- 2 U (mean) to 110 +/- 3 mm Hg and 33 +/- 1 U, respectively (p less than 0.05); heart rate remained unchanged. Cardiac output increased as a result of augmented cardiopulmonary volume (p less than 0.05) produced by peripheral venoconstriction and norepinephrine release (from 258 +/- 41 to 319 +/- 42 pg/ml; p less than 0.01). Surprisingly, there was an immediate reduction in plasma aldosterone (10.4 +/- 1.2 to 6.5 +/- 1.0 ng/dl; p less than 0.01), serum potassium (4.3 +/- 0.1 to 3.6 +/- 0.1 mEq/dl; p less than 0.001) and calcium (9.5 +/- 0.1 to 8.8 +/- 0.1 mg/dl; p less than 0.001) concentrations, whereas epinephrine increased (21.2 +/- 3.3 to 45.8 +/- 5.9 pg/ml; p less than 0.002). Previous studies with diltiazem, conducted similarly, did not show these changes. Therefore, clentiazem reduced mean arterial pressure through a decrease in total peripheral resistance, and released epinephrine was associated with intracellular potassium influx (urinary potassium did not change). The inhibited aldosterone release was not compensated by altered renal blood flow, glomerular filtration or increased plasma renin activity. These findings underscore the concept that calcium antagonists are a remarkably heterogeneous antihypertensive group.

Hemodynamic comparison of two nifedipine formulations in patients with essential hypertension

The hemodynamic and humoral effects and trough-to-peak 24-hour blood pressure responses of 2 nifedipine formulations, capsules and continuous-release once-daily formulation tablets, were evaluated in 10 patients with mild to moderate essential hypertension. Both formulations reduced mean arterial pressure similarly from 120 +/- 3 (baseline) to 107 +/- 2 (p less than 0.005) and 105 +/- 2 mm Hg (p less than 0.005) and total peripheral resistance index from 65 +/- 9 (baseline) to 47 +/- 4 (p less than 0.05) and 45 +/- 3 U/m2 (p less than 0.05), respectively. Renal, splanchnic and total forearm (including skin and skeletal muscle) blood flows were maintained or even increased slightly associated with reductions in regional vascular resistances. Decreases in renal, total forearm and skeletal muscle resistances were significant (p less than 0.05) with the capsules, but the decrease was only significant in renal resistance with the long-acting tablets. Intravascular volume did not expand with reduction in arterial pressure. This antihypertensive effect was not related to baseline plasma renin activity levels or age. Nifedipine tablets provided a better control of mean arterial pressure (66%) than did capsules (44%).

Left ventricular filling and stress response pattern in essential hypertension

PURPOSE

To evaluate whether impaired left ventricular filling determines the hemodynamic responses to isometric and orthostatic stress in a population with mild essential hypertension.

PATIENTS AND METHODS

The study population consisted of 32 patients with essential hypertension who were subdivided into those with preserved left ventricular filling (15 patients) and those with impaired left ventricular filling (17 patients). Echocardiograms were obtained before hemodynamic assessment was performed. Isometric stress and head-up tilt tests were done with a recovery period of at least 10 minutes between each to allow for blood pressure and heart rate to return to baseline. Hemodynamic reassessment was performed during the last minute of each test and at the end of the recovery period. Plasma epinephrine, norepinephrine, and dopamine levels were determined by radioenzymatic method.

RESULTS

Isometric stress increased mean arterial pressure by 30% (p less than 0.0001) by an increase in cardiac output (p less than 0.0001) and total peripheral resistance (p less than 0.0001) associated with an increase in plasma catecholamine levels (p less than 0.0001). Patients with preserved left ventricular filling had an increase in arterial pressure predominantly through an elevation in cardiac output (17%, p less than 0.0001) associated with a small increase in plasma norepinephrine levels (p less than 0.05) and in peripheral resistance (11%, p less than 0.05). In contrast, patients with impaired left ventricular filling had an increase in arterial pressure mainly through an increase in peripheral resistance (25%, p less than 0.0001) that was associated with a 45% elevation in plasma norepinephrine levels (p less than 0.0001). Orthostatic stress (passive head-up tilt) caused an exaggerated decrease in stroke volume (p less than 0.01) and cardiac output (p less than 0.01) in patients with impaired left ventricular filling when compared with those with preserved diastolic function.

CONCLUSION

Impaired left ventricular filling blunts the response of the heart to isometric and orthostatic stress. As a consequence, hypertensive patients with impaired ventricular filling respond to these stressors with enhanced sympathetic stimulation and exaggerated vasoconstriction.

Hemodynamic effects of celiprolol in essential hypertension

The immediate and short-term (2 week) hemodynamic and humoral effects of the beta-1 antagonist, beta-2 agonist, celiprolol, were compared with those of more prolonged atenolol therapy in 12 patients with essential hypertension. Celiprolol produced an immediate dose-dependent decrease in mean arterial pressure (113 +/- 3 to 102 +/- 2 mm Hg; p less than 0.001) and total peripheral resistance (49 +/- 3 to 38 +/- 1 U/m2; p less than 0.005) that was associated with an increased heart rate (67 +/- 1 to 73 +/- 2 beats/min; p less than 0.01) and cardiac index (2,347 +/- 129 to 2,708 +/- 111 ml/min/m2; p less than 0.01). Both celiprolol and atenolol reduced mean arterial pressure with short-term treatment (p less than 0.01); this was associated with a reduced total peripheral resistance with celiprolol (from 24 +/- 1 to 21 +/- 1 U/m2; p less than 0.02) and was not observed with atenolol. Moreover, in contrast with atenolol, celiprolol did not change heart rate or stroke and cardiac indexes. Splanchnic and forearm vascular resistances decreased with celiprolol (p less than 0.05) but not with atenolol; neither beta-blocking drug altered renal blood flow. These results demonstrate that the hemodynamic effects of celiprolol were strikingly different from atenolol; celiprolol reduced arterial pressure and total peripheral and certain vascular resistances without altering heart rate, cardiac index or regional blood flows. These effects may be explained by celiprolol's cardiac beta-1 receptor inhibitory and peripheral beta-2 receptor agonistic effects.

Cardiovascular effects of isradipine in essential hypertension

The immediate and short-term cardiovascular effects of oral isradipine therapy were evaluated in 11 patients with mild to moderate systemic hypertension. Isradipine, 5 mg administered orally, induced a significant reduction in arterial pressure from 165 +/- 6/88 +/- 3 mm Hg to 140 +/- 5/76 +/- 2 mm Hg (p less than 0.001) within 2.5 hours by a decrease in total peripheral resistance associated with an increase in heart rate and cardiac output. Contrary to the acute effect, oral therapy with isradipine for 3 months reduced arterial pressure through a decrease in total peripheral resistance but without causing an increase in heart rate or cardiac output or activation of the sympathetic nervous system. Isradipine slightly reduced left ventricular mass and improved cardiac systolic function and left ventricular filling. Renal blood flow increased, and renal vascular resistance (p less than 0.01) and total blood volume (p less than 0.002) decreased without a change in either sodium excretion or body weight. Thus, isradipine, when given for 3 months, decreased arterial pressure by reducing total peripheral resistance without activation of reflexive mechanisms. Its favorable effects on systemic hemodynamics, total blood volume, renal blood flow, and cardiac structure and function suggest isradipine to be an excellent choice for antihypertensive therapy.

Left ventricular filling in the systemic hypertension of obesity

Cardiac structure and systolic as well as diastolic functions were evaluated by 2-dimensional M-mode echocardiography in lean and obese patients who were either hypertensive or normotensive. Diastolic function, as assessed by diminished normalized early peak filling rate and prolonged duration of rapid filling, was decreased in hypertensive patients compared with normotensive patients (p = 0.02). When compared with lean patients with similar blood pressure levels, obese patients exhibited a lower normalized peak filling rate (p = 0.0014) but no difference in duration of rapid filling. A significant correlation was observed between the normalized peak filling rate and either body mass index or left ventricular (LV) mass (r = 0.355 and r = -0.32, respectively; p less than 0.001). Obese patients had greater LV end-diastolic and systolic dimensions (p less than 0.005 and p less than 0.02, respectively), LV wall thickness (p less than 0.05) and LV mass (p less than 0.007) than lean patients. Impairment of LV filling was most pronounced in obese hypertensive patients. It is concluded that the burden on the left ventricle imposed by obesity causes cardiac enlargement and impairment of LV filling regardless of levels of arterial pressure.

Impact of age, race, and obesity on hypertensive mechanisms and therapy

Despite the demonstrated efficacy of traditional antihypertensive therapy in reducing blood pressure, hypertension continues to be a major cause of cardiovascular disease morbidity and mortality. Stepped-care therapy is a nonphysiologic approach that, due to potential metabolic derangements and stimulation of undesirable reflex responses, may not substantially reduce the cardiovascular and renal complications associated with hypertension or improve long-term survival in many hypertensive patients. Because of fundamental hemodynamic differences related to the age, race, and weight of hypertensive patients, drug treatment often elicits varying responses. Certain classes of drugs are not only more effective but also more appropriate from a physiologic standpoint in specific types of patients. Therapy selection based in part on hemodynamic mechanisms and demographic patterns is a more rational approach to patient management and may contribute to a better overall outcome than has been observed with conventional treatment.

Renal hemodynamics and the renin-angiotensin-aldosterone system in normotensive subjects with hypertensive and normotensive parents

BACKGROUND AND METHODS

The kidney is important in blood-pressure regulation, but its role in the development of essential hypertension is still subject to debate. We compared renal hemodynamics, measured in terms of the clearance of para-aminohippuric acid and inulin, and the characteristics of the renin-angiotensin-aldosterone system in three groups of normotensive subjects at different degrees of risk for hypertension: 41 subjects with two normotensive parents, 52 with one normotensive and one hypertensive parent, and 61 with two hypertensive parents. The subjects ranged in age from 7 to 32 years.

RESULTS

The mean renal blood flow was lower in the subjects with two hypertensive parents than in those with two normotensive parents (mean difference [+/- SE], 198 +/- 61 ml per minute per 1.73 m2 of body-surface area; P = 0.002). Moreover, both the filtration fraction and renal vascular resistance were higher in the subjects with two hypertensive parents (filtration fraction: mean difference, 3.0 +/- 1.1 percentage points; P = 0.006; renal vascular resistance: mean difference, 2.7 +/- 0.8 mm Hg per deciliter per minute per 1.73 m2; P = 0.006). The subjects with two hypertensive parents had lower plasma concentrations of renin (mean difference, 3.3 +/- 1.6 mU per liter; P = 0.03) and aldosterone (mean difference, 111 +/- 36 pmol per liter; P = 0.003) than those with two normotensive parents. The differences could not be explained by the small differences in blood pressure between the groups. The values in the subjects with one hypertensive and one normotensive parent fell between those for the other two groups.

CONCLUSIONS

Renal vasoconstriction is increased and renin and aldosterone secretion is decreased in young persons at risk for hypertension. These findings support the hypothesis that alterations in renal hemodynamics occur at an early stage in the development of familial hypertension.

Immediate and short-term cardiovascular effects of fosinopril, a new angiotensin-converting enzyme inhibitor, in patients with essential hypertension

Immediate and short-term cardiovascular effects of a new angiotensin-converting enzyme inhibitor, fosinopril, were assessed in 10 patients with mild to moderate essential hypertension. Administration of a 10 mg oral dose of fosinopril reduced mean arterial pressure (p less than 0.001) as a result of a 24% fall in total peripheral resistance (p less than 0.001). Short-term therapy (12 weeks) maintained the decrease in mean arterial pressure (p less than 0.05) by decreasing total peripheral resistance (p less than 0.01), without reflexive cardiac stimulation or expanding intravascular volume. Renal vascular resistance decreased (p less than 0.05) while renal blood flow, glomerular filtration rate and filtration fraction remained unchanged. The response pattern to mental, isometric and orthostatic stress was similarly unchanged. Left ventricular mass diminished by 11% (p less than 0.01); myocardial contractility was unaffected. Afterload was reduced (p less than 0.05), and velocity of circumferential fiber shortening and stroke volume increased (p less than 0.05). Thus, arterial pressure reduction produced by fosinopril was associated with improved systemic and renal hemodynamics and reduced left ventricular mass.

Vasodilatory beta-blockers: systemic and regional hemodynamic effects

The systemic and regional hemodynamic alterations in hypertension and of the beta-adrenergic receptor inhibiting agents are reviewed. Hemodynamically, hypertension may be regarded as persistent elevation of arterial pressure associated with increased total peripheral resistance. In early or mild essential hypertension, however, increased total peripheral resistance may not readily be recognized because of the overriding effect of increased cardiac output. Clearly, the hemodynamics of blood pressure control are complex, and the mechanisms of antihypertensive agents must be used appropriately. The early beta-blockers reduced heart rate and cardiac output immediately after intravenous administration without immediately reducing arterial pressure, and calculated total peripheral resistance was increased. With prolonged oral treatment, arterial pressure decreased while maintaining a reduced heart rate and cardiac output. Total peripheral resistance, however, remained elevated. Recent beta-blockers, such as celiprolol, provide an improved physiologic response by instantly reducing arterial pressure and total peripheral resistance without reducing heart rate or cardiac output or expanding intravascular volume.

Stress-induced changes in blood pressure and left ventricular function in mild hypertension

Left ventricular function was studied by M-mode echocardiography at rest and during a mental arithmetic stress test and a cold-pressor test in 14 patients with mild hypertension and in 14 matched normotensive subjects. The elevation of blood pressure at rest in the hypertensive group (154 +/- 4/87 +/- 3 vs. 120 +/- 3/66 +/- 3 mmHg in the control group) was due mainly to a higher cardiac output (6.0 +/- 0.3 vs. 5.0 +/- 0.3 L/min), which was related to elevations of stroke volume and heart rate (73 +/- 2 vs. 66 +/- 2 beats/min). Venous plasma catecholamines were similar in the two groups. Mental stress induced cardiac output-dependent increases in blood pressure in both groups; systemic vascular resistance tended to decrease. The relative increases in diastolic and mean arterial blood pressure were smaller in the hypertensive group (15 vs. 26% and 15 vs. 21%, respectively), which exhibited signs of a reduced cardiac compliance, possibly related to a left ventricular hypertrophy. Mental stress elevated venous plasma adrenaline similarly in the two groups; effects on noradrenaline were small. The cold-pressor test increased blood pressure similarly in the two groups, largely due to increased systemic vascular resistance; plasma noradrenaline responses were also similar. Mental stress appears to elicit a differentiated sympathetic nerve activation pattern resembling the hypothalamic defense reaction. Mild hypertension seems to be associated with increased arousal and cardiac activation at rest. However, an attenuated blood pressure reactivity to mental stress may reflect reduced stroke volume responsiveness, which is related to structural changes, as heart rate reactivity tended to be enhanced in mild hypertension.

When is discontinuation of antihypertensive therapy indicated?

Major advances have been established in the handling of hypertensive vascular disease in recent years. However, drug compliance, drug costs, and the side effects of antihypertensive agents have prompted the question of whether intermittent therapy or even possible removal of medication represents an alternative to life-long antihypertensive therapy. Several case reports, and controlled and uncontrolled studies, have focused on this subject, delivering promising but inconsistent results. In this review the attempt is made to clarify the controversial results in order to provide possible selection criteria for patients who can be assumed to benefit from the withdrawal of antihypertensive medication. In addition, the issue of whether a genuine hypertensive can ever become normal is critically reviewed, and an evaluation of the reported success rates is performed. Factors that predicted a successful withdrawal of medication were young age, normal body weight, low salt intake, low pretreatment blood pressure, successful therapy with one drug, and only minimal signs of target organ damage. Additional modification, such as a low-salt or a weight-loss diet, were demonstrated to extend the period of nonpharmacologic treatment. Nevertheless, further studies would be of great help in elucidating how long and how intensively hypertensive patients should be treated before the discontinuation of medication can be tested.

Systemic and regional hemodynamics in patients with salt-sensitive hypertension

Twenty-two patients with normal plasma renin and essential hypertension were classified as "salt-sensitive" (SS) (n = 9) or "non-salt-sensitive" (NSS) (n = 13) from an increase in mean blood pressure with changes in sodium intake from 25 to 250 meq/day. With the high sodium diet, the SS patients gained more weight (p less than 0.05), retained more sodium (p less than 0.05), and had a greater increase in cardiac output (p less than 0.05). Despite the markedly increased cardiac output, systemic vascular resistance did not change with sodium loads in the SS patients, whereas the NSS patients had a significant decrease in systemic vascular resistance. Thus, the greater increase in blood pressure with sodium loads in SS patients can be attributed not only to an increase in cardiac output, possibly resulting from greater sodium retention, but also to inappropriately elevated systemic vascular resistance. Concomitant with a greater increase in cardiac output, the SS patients had a greater increase in forearm blood flow with sodium loading than the NSS patients (p less than 0.02). In contrast, blood flow to the kidney and the liver was not significantly changed in either group; renal (p less than 0.05) and hepatic (p less than 0.01) vascular resistance increased significantly in SS patients but remained unchanged in NSS patients. Thus, evidence presented suggests that the greater increase in blood pressure with sodium loads seems to be characterized by a very inhomogenous distribution of local flow and resistance in SS patients; renal and hepatic blood flow remains essentially unchanged and skeletal muscle blood flow receives almost all of the increase in cardiac output. Moreover, systemic vascular resistance changes did not reflect the resistance of individual beds because vasoconstriction appeared in the kidney and the splanchnic area but was masked by prominent vasodilation in the skeletal muscle. Because this hemodynamic pattern is similar to the pattern evoked during defense reaction, it is suggested that sympathetic overactivity on a selective basis might be involved in the impaired renal function for sodium excretion and the increase in blood pressure with sodium loads in SS patients.

Hemodynamic differences between black patients and white patients with essential hypertension. State of the art lecture

Physiological studies reported from our laboratory over the past several years have been reviewed and support epidemiological reports indicating that hypertensive cardiac and vascular disease runs a more severe course in the black patient. Although comparison of systemic hemodynamics failed to demonstrate that, for any level of arterial pressure, the magnitude of total peripheral resistance (which is the hemodynamic hallmark of hypertensive disease) differed between black patients and white patients, there are more subtle differences that were ascertained. Thus, although intravascular (plasma) volume contracts as arterial pressure and total peripheral resistance increase in both racial groups, this relation may differ quantitatively. At least in some black patients (43%), intravascular volume may be more expanded; in these patients, this relation is less closely correlated with the renopressor system (i.e., plasma renin activity). Moreover, these studies indicated that, at any level of arterial pressure, cardiac (left ventricular mass and posterior wall thickness) and renal hemodynamic involvement is more severe in the black patient. These findings point to important differences that operate in black patients and white patients with essential hypertension. With further study, these findings may be translated into more specific antihypertensive therapeutic implications for patients of both racial groups with essential hypertension.

Left ventricular diastolic function in normotensive adolescents with different genetic risk of hypertension

Abnormalities of the diastolic function of the left ventricle are the first sign of cardiac involvement in arterial hypertension. We have studied the diastolic function in a group of normotensive adolescents with confirmed family history of hypertension. M-mode echocardiography was performed in 86 normotensive males aged 14-19 years: 41 sons of at least one hypertensive parent (SHT) and 45 sons of normotensive parents (SNT). Cross-sectional area of the left ventricle and left ventricular (LV) mass index were significantly greater in the SHT than in the SNT group (10.05 +/- 1.84 vs. 8.9 +/- 1.56 cm/m2, p less than 0.01 and 129.3 +/- 296.3 vs. 109.23 +/- 25.7 g/m2, p less than 0.002, respectively). No significant difference between the two groups was observed in the indices of left ventricular diastolic function, except for mitral valve opening rate (463.51 +/- 90.45 in SHT vs. 416.71 +/- 78.84 mm/s in SNT; p less than 0.02). From the analysis of the subgroup of adolescents having left ventricular mass greater than the upper normal value, we observed that they showed mean time of rapid filling significantly longer than SNT: this could represent an early marker of the pathological character of such hypertrophy. Our results suggest that the higher LV mass observed in the SHT is not associated with chamber and myocardial stiffness abnormalities.

Management of mild hypertension

The benefits of blood pressure reduction have been clearly established for diastolic pressures of more than 100 mm Hg. For patients with a diastolic pressure between 90 and 99 mm Hg on repeated measurements, treatment should be initiated if other risk factors are present--for example, a family history of coronary risk, increased cholesterol level, male sex, smoking, or diabetes mellitus. When the pressure seems to be labile or exaggerated in the office, home or ambulatory readings may provide confirmatory information. For persons with diastolic pressures in the range of 90 to 94 mm Hg, it may be suitable to initiate therapy with nonpharmacologic maneuvers such as sodium restriction, weight reduction, and physical conditioning. In such cases, careful follow-up of blood pressure is particularly important because it may increase later. The initial therapy for mild hypertension should be selected to minimize adverse effects and should be tailored to the individual patient. Management of all levels of hypertension must be considered in light of the associated risk factors and a concomitant effort to minimize cardiovascular risk.

Effort blood pressure control in the course of antihypertensive treatment

In 30 patients with mild hypertension (diastolic blood pressure, 95 to 105 mmHg), the antihypertensive effect of rilmenidine 1 mg was compared in a double-blind study, with the effect of hydrochlorothiazide 25 mg. Patients not satisfactorily controlled received a combined therapy on the same doses of the two drugs used. Rilmenidine and hydrochlorothiazide induced a significant reduction (p = 0.01) of supine and erect systolic/diastolic blood pressure 23 hours after drug intake with no change in heart rate. This effect was due to a reduction in cardiac output (bioimpedance method) significant (p = 0.05) only for rilmenidine. Both drugs controlled the increase of effort systolic blood pressure in comparison with placebo on systemic vascular resistance treadmill exercise testing. Effort cardiac output was increased by each treatment in comparison with baseline values. Both at rest and on exertion, there was no effect on systemic vascular resistance induced by the two drugs. In a second group of 10 patients with moderate hypertension (diastolic blood pressure, 105 to 115 mmHg), rilmenidine 1 mg was administered in order to evaluate its efficacy and hemodynamic effects (bioimpedance and radionuclide ventriculography), at rest and during a lying cycloergometer effort test. The drug induced a significant decrease in blood pressure at rest and on exertion four hours after drug intake. This effect was due to a reduction (p = 0.05) in systemic vascular resistance, whereas cardiac output and heart rate remained unchanged. Our results show that the reduction in systolic/diastolic blood pressure induced by rilmenidine 1 mg is comparable with that induced by the well-known antihypertensive drug hydrochlorothiazide in mild hypertension. In moderate hypertension, the 1-mg dose appears to be insufficient in controlling the blood pressure in all patients. The drug exerts its antihypertensive effect through the normalization of the altered hemodynamic parameters of hypertension (high cardiac output and/or increased systemic vascular resistance). Rilmenidine also respects the physiologic increase in blood pressure and cardiac output on exertion.