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Zion AS, Izzo JL. Combination therapy with aliskiren and amlodipine in hypertension: treatment rationale and clinical results. Expert Rev Cardiovasc Ther 2014; 9:421-7. [DOI: 10.1586/erc.11.23] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Carpenter RJ, Dillard J, Zion AS, Gates GJ, Bartels MN, Downey JA, De Meersman RE. The Acute Effects of Acupuncture Upon Autonomic Balance in Healthy Subjects. Am J Chin Med 2012; 38:839-47. [DOI: 10.1142/s0192415x10008287] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Restoration of the sympathovagal (S/V) balance, involving a lowering of sympathetic and/or an augmentation of vagal modulation or a combination of both is associated with improvements in cardiovascular morbidity and mortality. To determine whether acupuncture exerts a favorable influence upon resting blood pressure and sympathovagal balance, a single-blind cross-over investigation was used to study the acute effects of acupuncture on S/V balance in normal healthy subjects. The ANOVA revealed a significant lowering of the sympathovagal balance (LF:HF) during rest for the acupuncture treatment from pre (4 ± 2 nu) to post (2.2 ± 1.8 nu)(p < 0.05). No such change was seen during sham treatment. The ANOVA revealed significant differences in systolic blood pressures during rest (114 ± 4 vs. 108 ± 3 mmHg) for the acupuncture treatment (p < 0.05). No significance was found during the sham treatment. The ANOVA failed to reveal any significant improvements in sympathovagal balance during the sustained isometric contraction. The clinical significance of these findings appears to suggest that acupuncture treatment might be beneficial in lowering blood pressure at rest. Furthermore, the lowering of the blood pressure might be in part due to a lowering of the sympathovagal balance. These findings are of importance since acupuncture treatments are non-pharmacological and have no known detrimental side-effects. This investigation employed healthy volunteers, yet acupuncture has been found to have more potent effects in animal models of hypertension and or in the presence of an autonomic imbalance.
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Affiliation(s)
- Rosann J. Carpenter
- Department of Rehabilitation Medicine, College of Physicians and Surgeons of Columbia University and Department of Biobehavioral Sciences, Teachers College, Columbia University, New York, NY 10027, USA
| | - James Dillard
- Department of Rehabilitation Medicine, College of Physicians and Surgeons of Columbia University and Department of Biobehavioral Sciences, Teachers College, Columbia University, New York, NY 10027, USA
| | - Adrienne S. Zion
- Department of Rehabilitation Medicine, College of Physicians and Surgeons of Columbia University and Department of Biobehavioral Sciences, Teachers College, Columbia University, New York, NY 10027, USA
| | - Gregory J. Gates
- Department of Rehabilitation Medicine, College of Physicians and Surgeons of Columbia University and Department of Biobehavioral Sciences, Teachers College, Columbia University, New York, NY 10027, USA
| | - Matthew N. Bartels
- Department of Rehabilitation Medicine, College of Physicians and Surgeons of Columbia University and Department of Biobehavioral Sciences, Teachers College, Columbia University, New York, NY 10027, USA
| | - John A. Downey
- Department of Rehabilitation Medicine, College of Physicians and Surgeons of Columbia University and Department of Biobehavioral Sciences, Teachers College, Columbia University, New York, NY 10027, USA
| | - Ronald E. De Meersman
- Department of Rehabilitation Medicine, College of Physicians and Surgeons of Columbia University and Department of Biobehavioral Sciences, Teachers College, Columbia University, New York, NY 10027, USA
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Abstract
While it may seem at first that antihypertensive drug combinations run counter to the desire to 'personalize' the management of hypertension, the best combinations have predictable efficacy in different individuals and subpopulations. Race is probably not a valid surrogate for clinically meaningful genetic variation or guide to therapy. Most guidelines suggest similar blood pressure goals for different races but drug treatment recommendations have diverged. In the United States, race is not considered to be a major factor in drug choice, but in England and other countries, initial therapy with renin-angiotensin system blocking drugs is not recommended in Blacks. In this review we: (1) examine new trends in race-based research; (2) emphasize the weaknesses of race-based treatment recommendations; and (3) explore the effects of a new combination, renin inhibition (aliskiren) and amlodipine, in African Americans.
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Affiliation(s)
- Joseph L Izzo
- Department of Medicine, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, 462 Grider Street, Buffalo, NY 14215, USA.
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Izzo JL, Zion AS. Value of Angiotensin receptor blocker therapy in diabetes. J Clin Hypertens (Greenwich) 2011; 13:290-5. [PMID: 21466628 PMCID: PMC8673251 DOI: 10.1111/j.1751-7176.2011.00447.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Revised: 01/31/2011] [Accepted: 01/31/2011] [Indexed: 11/26/2022]
Abstract
There are more clinical trials investigating angiotensin receptor blockers (ARBs) in diabetes than any other drug class, ranging from early "prevention" trials to the treatment of individuals with advanced organ damage. In its earliest manifestations, visceral adiposity predisposes to hypertension and hyperglycemia (metabolic syndrome). In these individuals, ARB therapy delays the progression to chronic hypertension and may also delay the progression to overt diabetes. Based on the increased cardiovascular disease risk of the metabolic syndrome, which is similar to stage 1 hypertension, both lifestyle modification and ARB therapy are justifiable. ARB therapy has also been found to delay the onset of microalbuminuria and retinopathy. In established diabetic nephropathy, ARB therapy is recommended as a standard alternative to angiotensin-converting enzyme inhibition to reduce macroalbuminuria and delay the progression to end-stage disease. Finally, large trials in ischemic heart disease, heart failure, and stroke have demonstrated clear benefits of ARB therapy. Because ARBs have side effect rates equal to placebo and far lower than any other antihypertensive drug class, the benefit/risk ratio is highly favorable across the entire spectrum of diabetic disease. Thus, ARB therapy is a highly attractive alternative for individuals at any stage of diabetes and with any pattern of complications.
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Affiliation(s)
- Joseph L Izzo
- Department of Medicine, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14215, USA.
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Wyatt J, Nandish S, Oliveros R, Zion AS, Lujan MS, Chilton R. Effect of glitazones on the progression of coronary artery disease in type 2 diabetes patients. Vasc Health Risk Manag 2010; 6:1-8. [PMID: 20191077 PMCID: PMC2828106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Indexed: 11/26/2022] Open
Abstract
The effect of thiazolidinediones (TZDs) on the progression of atherosclerosis in diabetes patients remains unclear. There has been heightened interest in recent years in this class of diabetes medications due to the non-glycemic lowering effects, such as altering lipids, inflammation and hematologic profiles. There have been several exciting studies over the past few years focused on the mechanism of action of the TZDs with respect to alteration in the cardio-metabolic profile in diabetes patients. New tools such as intravascular ultrasound have been used to follow plaques characteristics over time on a much more sensitive scale than has ever been possible in the past by coronary angiograms. These advances have enabled researchers to follow closely the macrovascular effects of different anti-atherosclerotic medications such as statins and TZDs. This article reviews the pathophysiology of atherosclerosis in diabetes, the role that TZDs play in this process and the imaging trials looking at the progression or regression of atherosclerosis in patients treated with TZDs.
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Affiliation(s)
- Jamison Wyatt
- University of Texas Health Science Center, San Antonio, Texas, USA
| | - Shailesh Nandish
- University of Texas Health Science Center, San Antonio, Texas, USA
| | - Rene Oliveros
- University of Texas Health Science Center, San Antonio, Texas, USA
| | | | - Michael S Lujan
- University of Texas Health Science Center, San Antonio, Texas, USA
| | - Robert Chilton
- University of Texas Health Science Center, San Antonio, Texas, USA;,Correspondence: Robert Chilton, Professor of Medicine, University of Texas, Health Science Center, San Antonio, Texas, 78261, USA, Tel +1 2105674601, Email
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Zion AS. Discovering medical education: a circuitous road to success. Physiologist 2008; 51:102-104. [PMID: 18595300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
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Spierer DK, DeMeersman RE, Kleinfeld J, McPherson E, Fullilove RE, Alba A, Zion AS. Exercise training improves cardiovascular and autonomic profiles in HIV. Clin Auton Res 2007; 17:341-8. [PMID: 18049834 DOI: 10.1007/s10286-007-0441-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2007] [Accepted: 08/06/2007] [Indexed: 11/29/2022]
Abstract
OBJECTIVES Human immunodeficiency virus (HIV) is associated with cardiovascular (CV) and autonomic dysfunction, however the effects of fitness on vascular and autonomic mechanisms in HIV disease are unknown. METHODS We studied forty-eight subjects (40.4 +/- 4.2 years) in a cross-sectional design matched for age, gender, BMI, and fitness. Participants were assigned to 1 in 4 groups: 1) Healthy Unfit (HU), 2) Healthy Fit (HF), 3) HIV Positive Unfit (HPU), and 4) HIV Positive Fit (HPF). Fitness was assessed via open-circuit spirometry; arterial compliance and autonomic modulations were measured via applanation tonometry and power spectral analysis, respectively, and baroreflex sensitivity was obtained using the alpha index. RESULTS Arterial compliance was augmented in HPF vs. HPU [7.4 +/- 1.9 mmHg x second vs. 4.4 +/- 1.7 mmHg x second (P = 0.006)]. Parasympathetic modulation was higher in HPF vs. HPU [2244.5 +/- 2997.6 msecond(2) vs. 489.1 +/- 552.9 msecond(2) (P < 0.05)]. Sympathetic modulation was lower in HPF vs. HU [4.7 +/- 5.0 mmHg(2) vs. 12.9 +/- 9.7 mmHg(2) (P < 0.05)]. Baroreflex sensitivity was higher in HPF vs. HPU [17.3 +/- 10.2 msecond/mmHg vs. 7.4 +/- 3.8 msecond/mmHg (P = 0.003)], and HPF vs. HU [17.3 +/- 10.2 msecond/mmHg vs. 6.2 +/- 3.0 msecond/mmHg (P = 0.004)]. CONCLUSIONS Augmentations in arterial compliance and baroreflex sensitivity associated with fitness portent an improved CV and autonomic profile for HIV-positive individuals. Physical activity may be an adjuvant method to enhance the overall vascular health in HIV-compromised individuals.
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Affiliation(s)
- David K Spierer
- Coler Goldwater Specialty Hospital and Nursing Facility, Roosevelt Island, NY, USA.
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Abstract
The decline in gonadal hormones during menopause gives rise to a wide range of physiological and psychological changes with the potential to significantly impact a woman's health and quality of life. Most notable among these are menopausal vasomotor symptoms, hot flushes and night sweats, along with mood and sleep disturbances. Given the biological and social significance of menopause, it is remarkable that the language used to describe this event and its associated symptoms is inconsistent. This review traces the history of Western medical writing about menopause-associated vasomotor symptoms and considers how terminology has contributed to the current confusion regarding symptoms and symptom reporting. Although hormone therapy is the only treatment for menopausal symptoms currently approved by the U.S. Food and Drug Administration, other forms of therapy are under evaluation. Agreement about the definition of menopause and its associated symptoms is critically important for the design and evaluation of new therapies and for the optimal treatment of women during this important phase of their lives.
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Affiliation(s)
- JoAnn V Pinkerton
- Department of Obstetrics and Gynecology, Division of Midlife Health, University of Virginia Health System, Charlottesville, 22908, USA.
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Zion AS, Bond V, Adams RG, Williams D, Fullilove RE, Sloan RP, Bartels MN, Downey JA, De Meersman RE. Low arterial compliance in young African-American males. Am J Physiol Heart Circ Physiol 2003; 285:H457-62. [PMID: 12738618 DOI: 10.1152/ajpheart.00497.2002] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hypertension remains a common public health challenge because of its prevalence and increase in co-morbid cardiovascular diseases. Black males have disproportionate pathophysiological consequences of hypertension compared with any other group in the United States. Alterations in arterial wall compliance and autonomic function often precede the onset of disease. Accordingly, our purpose was to investigate whether differences exist in arterial compliance and autonomic function between young, healthy African-American males without evidence of hypertension and age- and gender-matched non-African-American males. All procedures were carried out noninvasively following rest. Arterial compliance was calculated as the integrated area starting at the well-defined nadir of the incisura of the dicrotic notch to the end of diastole of the radial artery pulse wave. Power spectral analysis of heart rate and blood pressure variability provided distributions representative of parasympathetic and sympathetic modulations and sympathovagal balance. Baroreflex sensitivity (BRS) was calculated using the sequence method. Thirty-two African-American and twenty-nine non-African-American males were comparable in anthropometrics and negative family history of hypertension. t-Tests revealed lower arterial compliance (5.8 +/- 2.4 vs. 8.6 +/- 4.0 mmHg. s; P = 0.0017), parasympathetic modulation (8.9 +/- 1.1 vs. 9.7 +/- 1.1 ln ms2; P = 0.0063), and BRS (13.7 +/- 7.3 vs. 21.1 +/- 8.5 ms/mmHg; P = 0.0007) and higher sympathovagal balance (2.9 +/- 3.2 vs. 1.5 +/- 1.1; P = 0.03) in the African-American group. In summary, differences exist in arterial compliance and autonomic balance in African-American males. These alterations may be antecedent markers of disease and valuable in the detection of degenerative cardiovascular processes in individuals at risk.
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Affiliation(s)
- Adrienne S Zion
- Department of Rehabilitation Medicine, Mailman School of Public Health, College of Physicians and Surgeons, Columbia University, 630 West 168th Street, Box 38, New York, NY 10032
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Zion AS, Bartels MN, Wecht JM, Sloan RP, Downey JA, De Meersman RE. Evaluation of blood pressure and baroreflex sensitivity by radial artery tonometry versus finger arteriolar photoplethysmography. Am J Hypertens 2003; 16:371-4. [PMID: 12745198 DOI: 10.1016/s0895-7061(03)00039-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Published normative data of noninvasive blood pressures (BPs) and autonomic modulations have been primarily derived from the finger arteriole using the Finapres (Ohmeda Co., Englewood, CO), a device that is no longer manufactured. Currently, beat-to-beat BP are obtained from the radial artery using the Colin tonometer. METHODS We compared BP and autonomic parameters in a crossover design between the two devices in 29 subjects during seated rest and a 0.1-Hz breathing protocol. In addition, we tested whether finger arteriolar BP differences were due to pressure changes exerted by the radial tonometer. RESULTS Uniformly, BP measured at the radial artery were significantly higher than those from the finger arteriole. Radial BP (106 +/- 19.5 mm Hg) were higher than finger arteriolar BP (95.8 +/- 13.7 mm Hg) (P <.005). Tonometric baroreflex sensitivity (BRS) (24.0 +/- 18 msec/mm Hg) was higher compared to photoplethysmographic BRS (12.0 +/- 7.7 msec/mm Hg; P <.0003). Systolic BP (radial artery) (115 +/- 25 mm Hg) were higher compared to finger arteriolar BP (97.7 +/- 19 mm Hg; P <.0025) during breathing, as was BRS (25.9 +/- 11.6 msec/mm Hg v 21.5 +/- 11.6 msec/mm Hg; P <.05). Differences in the low frequency systolic BP (LF(SBP)), representative of sympathetic vasomotor modulation, between the two methods, whether absolute, normalized, or log-transformed were not observed. CONCLUSIONS There were no differences in arteriolar BP values in the presence or absence of radial artery tonometric pressure. These findings indicate that differences exist in systolic BP and BRS using the tonometer (radial artery) versus the Finapres (Ohmeda Co.) (finger arteriole). Furthermore, these differences are not due to pressure exerted by the radial artery tonometer that supplies blood to the finger arteriole.
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Affiliation(s)
- Adrienne S Zion
- Departments of Rehabilitation Medicine, College of Physicians & Surgeons, Teachers College Columbia University, New York, New York 10032, USA.
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Abstract
Loss of autonomic balance characterized by increased sympathetic activity and decreased vagal activity has been implicated as a major cardiovascular risk factor. Aspirin's cardioprotective abilities involve a multitude of physiologic processes. However, the effects of aspirin on cardiac autonomic activity are unknown. In a double-blind crossover study, 22 subjects randomly received either aspirin or placebo in the amounts of 325 mg with each meal (three times per day) over a 2.5-day period. The total amount of aspirin ingested was 2,275 mg, which resulted in plasma levels of 3.3 mg/dl. At the conclusion of each treatment, subjects were evaluated for autonomic physiology activity using standard autonomic tests. Power spectral analyses of the electrocardiograms were used to delineate autonomic function. A 2 x 4 repeated measures analysis of variance revealed significant and favorable changes in autonomic activity after the use of aspirin. Specifically, at rest high-frequency (HF) power was significantly higher (mean, 1,090 + 1,463.5 msec2) compared with the placebo (mean, 692 742 msec2) (p <0.05). Low-frequency (LF) power was significantly reduced (mean, 963 745 msec2) after aspirin compared with placebo (mean, 1,100 906 msec2). After the aspirin treatment, a significantly lower LF-to-HF power ratio (mean, 1.7 2 msec2) was noted at rest when compared with the placebo (mean, 2.5 2.7 msec2) (p <0.05). Similar significant trends were seen during the sustained isometric contraction after aspirin therapy for HF power (mean 210 2.15 msec2) compared with placebo (mean, 213 184 msec2) (p <0.05). Accordingly, the LF-to-HF power ratio was lower as well when compared to placebo treatment (mean, 2.3 3.5 msec2) (mean, 5.3 8.4 msec2) (p <0.05). No differences were found in breathing rates for hemodynamic variables between any of the protocols. The significant reduction of LF-to-HF ratio, a marker of sympathovagal balance, for both protocols appeared to be largely due to a withdrawal of LF modulation and concomitant but lesser increase in HF modulation. Favorable alterations in autonomic outflow through prostaglandin inhibition may be one of the mechanisms by which low therapeutic amounts of aspirin provide prophylactic cardioprotection.
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Affiliation(s)
- R E De Meersman
- Department of Rehabilitation Medicine and Teachers College, Columbia University, New York, New York 10032, USA.
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13
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Abstract
Mechanoreceptor contribution to efferent autonomic outflow is incompletely understood. To determine the effects of mechanoreceptor stimulation on autonomic reflexes, we compared autonomic responses in 34 subjects using a cross-over, counter-balanced design, in which hemodynamic, electromyographic, metabolic, and autonomic data were gathered during rest, passive, and active movement protocols. Because metaboreceptors and ventilatory responses influence autonomic outflow we verified and controlled for these influences during all protocols through comparisons of breath-by-breath gas exchange measurements. Verification of active and passive movements was made via electromyographic recordings of the moving legs. Spectral analysis of R-R variability was used to assess autonomic activity, and low to high frequency ratios were considered representative of sympathovagal balance. A repeated measures analysis of variance revealed significant modulating effects of mechanoreceptor stimulation on sympathovagal balance during passive movement upon efferent autonomic outflow (p < 0.01) independent of central command, chemoreceptor, and metaboreceptor stimulation. Furthermore, breathing frequency and volume were identical for both movement protocols. Therefore, findings in this investigation suggest that modulating influences are being exerted by mechanoreceptor stimulation on autonomic outflow to the heart.
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Affiliation(s)
- R E De Meersman
- College of Physicians & Surgeons, Columbia University, Department of Rehabilitation Medicine, New York, NY 10032, USA
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De Meersman RE, Zion AS, Giardina EG, Weir JP, Lieberman JS, Downey JA. Estrogen replacement, vascular distensibility, and blood pressures in postmenopausal women. Am J Physiol 1998; 274:H1539-44. [PMID: 9612361 DOI: 10.1152/ajpheart.1998.274.5.h1539] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The pathogenesis of blood pressure (BP) rise in aging women remains unexplained, and one of the many incriminating factors may include abnormalities in arteriolar resistance vessels. The aim of this study was to determine the effects of unopposed estrogen on arteriolar distensibility, baroreceptor sensitivity (BRS), BP changes, and rate-pressure product (RPP). We tested the hypotheses that estrogen replacement therapy (ERT) enhances arteriolar distensibility and ameliorates BRS, which leads to decreases in BP and RPP. Postmenopausal women participated in a single-blind crossover study; the participants of this study, after baseline measurements, were randomly assigned to receive estrogen (ERT) or a drug-free treatment with a 6-wk washout period between treatments. The single-blind design was instituted because subjects become unblinded due to physiological changes (i.e., fluid shifts, weight gain, and secretory changes) associated with estrogen intake. However, investigators and technicians involved in data collection and analyses remained blind. After each treatment, subjects performed identical autonomic tests, during which electrocardiograms, beat-by-beat BPs, and respiration were recorded. The area under the dicrotic notch of the BP wave was used as an index of arteriolar distensibility. The magnitude of the reflex bradycardia after a precipitous rise in BP was used to determine BRS. Power spectral analysis of heart rate variability was used to assess autonomic activity. BPs were recorded from resistance vessels in the finger using a beat-by-beat photoplethysmographic device. RPP, a noninvasive marker of myocardial oxygen consumption, was calculated. Repeated-measures analyses of variance revealed a significantly enhanced arteriolar distensibility and BRS after ERT (P < 0.05). A trend of a lower sympathovagal balance at rest was observed after ERT, however, this trend did not reach statistical significance (P = 0.061) compared with the other treatments. The above autonomic changes produced significantly lower systolic and diastolic BP changes and RPPs (P < 0.05) at rest and during isometric exercise. We conclude that short-term unopposed ERT favorably enhances arteriolar distensibility, BRS, and hemodynamic parameters in postmenopausal women. These findings have clinical implications in the goals for treating cardiovascular risk factors in aging women.
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Affiliation(s)
- R E De Meersman
- Department of Rehabilitation Medicine, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA
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15
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Abstract
Weight reduction, either by dietary or surgical means, is associated with prolongation of the heart rate corrected QT interval (QTc = QT/R-R0.5) and, on occasion, sudden death. Screening subjects with obesity before weight loss for prolonged QTc intervals is an accepted practice, although at present, there are no guidelines for whether subjects should be fasting before electrocardiogram (EKG) evaluation. The aim of this study was to test the hypothesis that EKG QTc interval duration is independent of meal ingestion. The hypothesis was tested in 11 healthy subjects who ingested a 500-kcal formula meal. A small decrease in absolute QT interval and a steady decline in R-R interval were observed for up to 60 minutes after formula ingestion. The QTc interval increased above baseline at 15 minutes (p < 0.007) after meal, a change that persisted for the 1-hour postmeal observation period. Spectral analysis of EKG R-R intervals (low-/high-frequency amplitude ratio) indicated a change in cardiac autonomic flow after meal ingestion. The QTc interval did not lengthen and R-R low-/high-frequency amplitude ratio remained unchanged in eight subjects evaluated in a similar manner but in whom isovolumic amounts of water replaced the meal. These observations suggest that (1) cardiac repolarization changes with fasting and feeding, (2) the QTc interval is influenced by meal intake, and (3) the autonomic nervous system may play a role in meal-related QTc changes. These findings have implications for the evaluation of patients with obesity before starting and during weight loss treatment.
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Affiliation(s)
- D Nagy
- Obesity Research Center, St. Luke's-Roosevelt Hospital, New York, NY 10025, USA
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Sloan RP, DeMeersman RE, Shapiro PA, Bagiella E, Chernikhova D, Kuhl JP, Zion AS, Paik M, Myers MM. Blood pressure variability responses to tilt are buffered by cardiac autonomic control. Am J Physiol 1997; 273:H1427-31. [PMID: 9321834 DOI: 10.1152/ajpheart.1997.273.3.h1427] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Variability in blood pressure (BPV) is influenced by vascular sympathetic drive as well as autonomic control of the heart. Evidence suggests that elimination of cardiac autonomic control, as measured by heart period variability (HPV), produces a reduction in BPV at rest but an increase in BPV during challenge. We recently showed that the BPV response to psychological challenge, which principally produces cardiac parasympathetic withdrawal, was inversely related to the subject's level of cardiac control. In the current study we examined the BPV response to orthostatic tilt, a sympathetic stressor. Subjects were 22 healthy men and women who differed in cardiac control due in part to differences in aerobic capacity. HPV and BPV were measured noninvasively on a beat-to-beat basis. Tilt produced significant increases in heart rate and diastolic blood pressure and a significant decrease in high frequency HPV. As predicted, changes in BPV in response to tilt were inversely related to resting HPV. Results are interpreted in terms of a model of cardiovascular control which holds that BPV originates from feedforward effects of central control of the heart, feedback effects mediated through the baroreflexes, and direct sympathetic vascular effects.
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Affiliation(s)
- R P Sloan
- Behavioral Medicine Program, Columbia-Presbyterian Medical Center, New York, New York, USA
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Sloan RP, Demeersman RE, Shapiro PA, Bagiella E, Kuhl JP, Zion AS, Paik M, Myers MM. Cardiac autonomic control is inversely related to blood pressure variability responses to psychological challenge. Am J Physiol 1997; 272:H2227-32. [PMID: 9176290 DOI: 10.1152/ajpheart.1997.272.5.h2227] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Blood pressure exhibits variability (BPV) at low (0.02- to 0.07-Hz), mid (0.07- to 0.15-Hz)-, and high (0.15- to 0.50-Hz) frequencies. Evidence suggests that BPV responses to challenge are inversely related to cardiac autonomic control. We tested this hypothesis by examining the BPV responses to psychological stressors in 22 normal subjects who differed in cardiac control, operationalized as resting heart period variability (HPV). HPV and BPV were measured noninvasively or a beat-to-beat basis. The stressors produced a significant increase in heart rate and a small but significant increase in diastolic blood pressure. As predicted, the changes in BPV in response to the stressors were inversely related to resting HPV. The results are interpreted in terms of a model of cardiovascular control that holds that BPV originates from feedforward effects of central control of the heart, feedback effects mediated through the baroreflexes, and direct sympathetic vascular effects.
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Affiliation(s)
- R P Sloan
- Behavioral Medicine Program, Columbia-Presbyterian Medical Center, New York, New York, USA
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De Meersman RE, Zion AS, Teitelbaum S, Weir JP, Lieberman J, Downey J. Deriving respiration from pulse wave: a new signal-processing technique. Am J Physiol 1996; 270:H1672-5. [PMID: 8928873 DOI: 10.1152/ajpheart.1996.270.5.h1672] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Investigations of autonomic nervous system activity using spectral analysis of heart rate (HR) and blood pressure (BP) variability is very popular in many scientific disciplines, and yet only half of all studies involving spectral analysis control for respiration. Because respiration modulates HR and BP variability, knowledge of the respiratory rate is necessary for the proper interpretation of HR and BP power spectra. We devised and validated a new signal-processing technique to derive respiration from the blood pressure wave. This technique is based on the relationship between oscillations in the area under the dicrotic notch of the pulse wave and respiration. The results of our view signal-processing technique yielded significant correlations between protocols of the actual number of respiratory cycles and our blood pressure-derived respiratory cycles and their respective spectra for a number of standard autonomic tests (P < 0.05). Our method will allow retrospective extraction of the respiratory wave and as such afford a more precise interpretation of HR and BP spectra.
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Affiliation(s)
- R E De Meersman
- Department of Rehabilitation Medicine, College of Physicians & Surgeons of Columbia University, New York, New York 10032, USA
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