Evaluation of Autonomic Influences on QT Dispersion Using the Head‐Up Tilt Test in Healthy Subjects

Nakagawa, Mikiko; Takahashi, Naohiko; Iwao, Tetsu; Yonemochi, Hidetoshi; Ooie, Tats±Hiko; Hara, Masahide; Saikawa, Tetsunori; Ito, Morio

doi:10.1111/j.1540-8159.1999.tb00595.x

Cited by 59 publications

(35 citation statements)

References 26 publications

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“…It should be emphasized that sympathetic autonomic responses in the elderly are diminished (9,13,48). Indeed, in contrast with our findings, a decrease in QTd was observed in young healthy individuals during the tilt test; similar to our model, the tilt test reduces venous return and activates adrenergic responses (31).…”

Section: Discussionsupporting

confidence: 52%

Acute reduction of ventricular volume decreases QT interval dispersion in elderly subjects with and without heart failure

Carvalho

Consolim‐Colombo

Pastore

et al. 2005

American Journal of Physiology-Heart and Circulatory Physiology

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To evaluate the effects of acute reduction in ventricular volume (VV) on QT interval dispersion (QTd), 14 men with heart failure (HF; 74.5 Ϯ 2 yr of age) and 11 healthy male control subjects (68 Ϯ 2 yr of age) were studied. For 15 min, lower body negative pressure (LBNP) was applied at Ϫ15 and Ϫ40 mmHg to reduce venous return. At baseline and during LBNP application, QTd was measured with an 87-lead, body-surfacemapping device; chamber volumes were assessed by radioisotope ventriculography; blood pressure (BP) and heart rate (HR) were continuously monitored; and blood samples were obtained for assessment of norepinephrine (Nor) levels. At Ϫ15 mmHg, LNBP application induced a significant decrease in VV but did not change BP and HR in both groups. In addition, Nor levels increased significantly (P Յ 0.05) in the control group (from 286.7 Ϯ 31.5 to 388.8 Ϯ 41.2 pg/ml) and in HF patients (from 405.8 Ϯ 56 to 477.6 Ϯ 47 pg/ml), and QTd was significantly (P Յ 0.05) decreased in the control group (57.2 Ϯ 3.8 vs. 49.1 Ϯ 3.4 ms) and in HF patients (67.8 Ϯ 6 vs. 63.7 Ϯ 5.9 ms). No additional decreases in VV or QTd were produced by Ϫ40 mmHg LNBP, but Nor levels did increase in both groups and reach 475.5 Ϯ 34 and 586.5 Ϯ 60 pg/ml (P Ͻ 0.05) in the control and HF groups, respectively; BP did not change, but HR also increased in both groups. In conclusion, an acute LBNP-induced reduction in VV caused a decrease in the QTd of elderly men regardless of the existence of HF. Because increased sympathetic activity with more intense LBNP was not accompanied by additional changes in QTd, altered QTd may be better related to changes in VV than to autonomic nervous system activity. lower body negative pressure; cardiomyopathy; cardiac; norepinephrine; ischemic disease HEART FAILURE (HF) is a highly prevalent and important cause of morbidity and mortality in the elderly population (20). Although improvements in HF therapy have lowered mortality caused by disease progression, nearly half of the patients with HF experience sudden death (22,34). Some studies (4,7,12,14,39) have suggested that QT interval dispersion (QTd) could be associated with a higher risk of sudden death. Indeed, some investigators (16, 44) have correlated structural alterations observed in HF with increased QTd and a worse prognosis. Thus a better prognosis due to the use of drugs that attenuate ventricular remodeling [e.g., angiotensin-converting enzyme (ACE) inhibitors] seems to be associated with a more homogeneous repolarization, which leads to a decrease in QTd (3).As a result, research to detect a possible relationship between QTd behavior and factors known to influence the prognosis of HF [e.g., ventricular dysfunction, ventricular volume (VV), and neurohormonal activation] can be very useful (1, 35). Among such factors, VV is the least complex variable to study. One model that induces acute reductions in VV consists of the application of lower body negative pressure (LBNP), whereby cardiac preload is decreased because of a reduction in venous return (10). Thi...

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Section: Discussionsupporting

confidence: 52%

Acute reduction of ventricular volume decreases QT interval dispersion in elderly subjects with and without heart failure

Carvalho

Consolim‐Colombo

Pastore

et al. 2005

American Journal of Physiology-Heart and Circulatory Physiology

View full text Add to dashboard Cite

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“…In fact, as shown by many studies in the literature (24)(25)(26)(27), a significant association is present between QTc dispersion and HRV. So, the contemporary evaluation of both these parameters should strengthen the significance of the results, and could lead to a firmer conclusion.…”

Section: Discussionmentioning

confidence: 76%

Changes in heart rate variability and QT dispersion in patients with overt hypothyroidism

Galetta¹,

Franzoni²,

Fallahi³

et al. 2008

European Journal of Endocrinology

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Objective: The aim of the present study was to evaluate the effect of clinical hypothyroidism on cardiovascular autonomic function and ventricular repolarization. Design and methods: We studied 31 patients (22 females and 9 males; mean age 53.6G11.8 years) with overt hypothyroidism (TSHZ56.2G14.7 mU/ml, low free thyroxine (T 4 ), free tri-iodothyronine (T 3 )) and 31 euthyroid controls, to investigate the dispersion of the QT interval in electrocardiogram (ECG) (an index of inhomogeneity of repolarization) and heart rate variability (HRV; a measure of cardiac autonomic modulation). The hypothyroid patients and controls underwent a full medical examination, standard 12-lead ECG, and 24-h ambulatory ECG monitoring. The hypothyroid patients were re-examined after 6 months of treatment with L-T 4 . Results: Patients with hypothyroidism showed higher QT dispersion and lower HRV measures than controls (P!0.01 or P!0.001). In hypothyroid patients, standard deviation of all R-R intervals was inversely related (by simple regression) to serum (log)TSH levels (rZK0.47, PZ0.008), while QT dispersion (rZ0.50, PZ0.004) and QTc dispersion (rZ0.46, PZ0.008) were directly related to (log)TSH. Parameters of HRV improved after 6 months of L-T 4 treatment, with the correction of hypothyroidism, becoming comparable with those of the control subjects, whereas the QT and QTc dispersion results were found to be only partially restored, remaining higher than the controls. Conclusions:The results of the study demonstrate that hypothyroidism is associated with a decreased sympatho-vagal modulation of the heart rate and with an increased inhomogeneity of ventricular recovery times. The assessment of HRV and QT dispersion in patients with overt hypothyroidism may represent a useful tool in monitoring the cardiovascular risks.European Journal of Endocrinology 158 85-90

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“…Head-up tilt induces prolongation of the QTD and QTcD due to increased sympathetic activity or decreased vagal tone. 13 Watanabe et al 16 reported that the neural control function of blood pressure during head-up tilt in the elderly differed from that in young subjects because of age-related change in baroreflex function. Since a head-up position induces decreases in venous return and cardiac output, a combination of intraperitoneal insufflation and head-up tilt causes further hemodynamic changes.…”

Section: Me Et Th Ho Od Ds Smentioning

confidence: 99%

“…1,2,[13][14][15] It is well known that intraperitoneal CO 2 insufflation during laparoscopic cholecystectomy induces hemodynamic changes. Previous studies have demonstrated that an increased abdominal pressure with CO 2 diminishes venous return and cardiac output, and increases MAP, HR, pulmonary capillary wedge pressure, systemic and pulmonary vascular resistances, and central venous pressure.…”

Section: Me Et Th Ho Od Ds Smentioning

confidence: 99%

QT interval and QT dispersion increase in the elderly during laparoscopic cholecystectomy: A preliminary study

Egawa

Minami

Fujii

et al. 2002

Can J Anesth/J Can Anesth

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P Pu ur rp po os se e: : To compare the influence of a longer duration of intraperitoneal CO 2 insufflation with head-up tilt on electrocardiogram indices during laparoscopic cholecystectomy between elderly and younger patients.M Me et th ho od ds s: : Twelve elderly and 12 younger patients were studied. In all patients, intraperitoneal CO 2 insufflation was performed for more than 150 min in the head-up position. RR interval, QT interval, the rate-corrected QT (QTc) interval, QT dispersion (QTD) and the rate-corrected QTD (QTcD) were measured.

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Evaluation of Autonomic Influences on QT Dispersion Using the Head‐Up Tilt Test in Healthy Subjects

Cited by 59 publications

References 26 publications

Acute reduction of ventricular volume decreases QT interval dispersion in elderly subjects with and without heart failure

Acute reduction of ventricular volume decreases QT interval dispersion in elderly subjects with and without heart failure

Changes in heart rate variability and QT dispersion in patients with overt hypothyroidism

QT interval and QT dispersion increase in the elderly during laparoscopic cholecystectomy: A preliminary study

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