Effect of different degrees of tilt on cardiac output, heart rate, and blood pressure in normal man.

Summary. The orthostatic reaction to tilting was studied in 46 diabetics without symptoms of autonomic neuropathy and in 31 age-matched healthy control subjects. After tilting, the diastolic blood pressure rose in the control subjects but was unchanged or tended to fall in the diabetics, except in those of short duration without retinopathy. After tilting, the control subjects showed an immediate increase in heart rate with the highest value at 8.4 + 1.0 s (mean _+ SEM), followed by a transient decrease with lowest value at 21.2 _+ 0.9 s. The acceleration and brake index measured the changes in heart rate.

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“…The diastolic blood pressure rises normally after tilting [9]. Here a lack of rise was shown in diabetics with retinopathy.…”

Section: Discussionmentioning

confidence: 90%

Abnormal diastolic blood pressure and heart rate reactions to tilting in diabetes mellitus

1980

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“…Nonetheless, several important issues can be addressed. In normal individuals, the gravitational stress of head up tilt is associated with peripheral pooling ofblood, reduction ofvenous return, and subsequent reduction of cardiac output (37,38). To protect and maintain blood pressure, head up tilt stimulates baroreceptor mechanisms that result in an increase of heart rate and systemic vascular resistance.…”

Section: Discussionmentioning

confidence: 99%

Sodium and water balance in chronic congestive heart failure.

Cody¹,

Covit²,

Schaer³

et al. 1986

J. Clin. Invest.

163

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As the characteristics of sodium and water balance in heart failure remain undefined, we evaluated the hemodynamic, metabolic, and hormonal effects of balanced sodium intake in 10 patients with chronic congestive heart failure. We discontinued diuretics to avoid their confounding influence, and all patients received 1 wk of 10 meq and 100 meq balanced sodium intake and controlled free water. Comparing sodium intake of 10 with 100 meq, the following observations were made. There was weight gain (2.0 kg) and increased sodium excretion (11±3 to 63±15 meq/24 h), unaccompanied by increase of blood volume. Both renin-angiotensin system and sympathetic nervous system activity were greater during the 10 meq diet, and suppressed with the 100 meq sodium diet. For both diets, plasma renin and urinary aldosterone excretion were correlated with urnary sodium excretion (r = -0.768, r = -0.726, respectively; P < 0.005). Systemic hemodynamics were minimally changed with increased sodium intake. However, reversal of vasoconstriction by captopril during the 10 meq diet, and its ineffectiveness during the 100 meq diet, indicated a renin-dependent mechanism in the former, and a renin-independent mechanism in the latter diet. There were two subgroups of response to the 100 meq diet: one group (a = 5) achieved neutral balance, while the second (a = 5) avidly retained sodium and water. Renin-angiotensin system activity was significantly higher in the latter group, and the mechanism for differences in sodium excretion for the subgroups could not be identified by blood volume or hemodynamic parameters. Orthostatic hypotension during tilt was greater during the 10 meq sodium diet, and in all cases, related to ineffective hemodynamic and hormonal compensatory responses.

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“…Studies in animal models and in humans have demonstrated abnormalities of sympathetic and parasympathetic control of heart rate in chronic congestive heart failure. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Few data are available regarding the effects of vasodilator therapy on these abnorrnalities, although this mode of therapy is widely used. '6 Vasodilator therapy could significantly alter the vasoconstriction, volume alterations and hormonal response that normally accompany the assumption of upright posture.…”

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confidence: 99%

Mechanisms governing the postural response and baroreceptor abnormalities in chronic congestive heart failure: effects of acute and long-term converting-enzyme inhibition.

Cody¹,

Franklin²,

Kluger³

et al. 1982

Circulation

140

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SUMMARYWe assessed the hemodynamic and hormonal response to tilt and the baroreceptor response in 12 patients in sinus rhythm with severe chronic congestive heart failure. We also assessed the response to acute (n = 12) and chronic (n = 8) converting-enzyme inhibition with captopril. The control tilt was characterized by high cardiac filling pressures, absence of significant peripheral pooling and apparent absence of afferent stimuli for hemodynamic and hormonal response. After acute captopril, the hemodynamic response to tilt was improved, but not normalized. The chronic response was characterized by the absence of a reflex increase of systemic vascular resistance on tilt despite peripheral pooling. Five patients developed orthostatic hypotension, but responded to acute infusion of 0.9% sodium chloride. Efferent sympathetic activity (response to cold pressor) was abnormal during the control study, but indistinguishable from normal subjects by the time of chronic captopril therapy. This paralleled an improved responsiveness of plasma catecholamines during chronic tilt. The Valsalva maneuver remained abnormal. There was a distinct absence of the normally anticipated heart rate increase on tilt, suggesting a parasympathetic abnormality.IN BOTH normal and hypertensive persons, upright posture is associated with significant peripheral pooling. 14 Orthostatic hypotension does not occur because reflex increase of systemic resistance and heart rate compensate for the peripheral pooling. Activation of the renin-angiotensin system and compensatory change of sympathetic and parasympathetic tone are also important adjustments.2' 5-8 Abelmann and Fareeduddin9' 10 demonstrated that the hemodynamic response to tilt in chronic congestive heart failure is atypical; that is, there was no significant peripheral pooling in the upright posture. Hence, reflex stimulation of increased systemic vascular resistance and heart rate did not appear necessary to avert orthostatic hypotension. This atypical response was attributed to intense volume expansion and vasoconstriction, but the interactions of controlling mechanisms are not known. Studies in animal models and in humans have demonstrated abnormalities of sympathetic and parasympathetic control of heart rate in chronic congestive heart failure. 1-15Few data are available regarding the effects of vasodilator therapy on these abnorrnalities, although this mode of therapy is widely used.'6 Vasodilator therapy could significantly alter the vasoconstriction, volume alterations and hormonal response that normally accompany the assumption of upright posture. This may have some influence on the reported discrepancy between supine and dynamic assessment of hemodynamic improvement during chronic vasodilator therapy of severe congestive heart failure.17 In the present study we reevaluated the factors contributing to the tilt response and baroreceptor function in severe chronic congestive heart failure. We assessed the effects of acute and chronic vasodilator therapy on these responses using the...

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Effect of different degrees of tilt on cardiac output, heart rate, and blood pressure in normal man.

Cited by 93 publications

References 9 publications

Abnormal diastolic blood pressure and heart rate reactions to tilting in diabetes mellitus

Abnormal diastolic blood pressure and heart rate reactions to tilting in diabetes mellitus

Sodium and water balance in chronic congestive heart failure.

Mechanisms governing the postural response and baroreceptor abnormalities in chronic congestive heart failure: effects of acute and long-term converting-enzyme inhibition.

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