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Elevated Heart Rate (elevated + heart_rate)
Selected AbstractsSex Differences in the Effect of Heart Rate on Mortality in the ElderlyJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 9 2003Gila Perk MD Objectives:, To examine the association between heart rate and mortality risk in the elderly. Design:, Longitudinal cohort. Setting:, Outpatient. Participants: Four hundred twenty-two people, aged 70 upon entry, were surveyed and followed for 6 years. Measurements: Pulse rate was measured manually, while sitting and standing, and heart rate was measured from electrocardiogram recordings. The population was divided into quartiles of heart rate, with the top quartile comprising those with heart rate greater than 77 beats per minute (bpm) and the bottom quartile those with heart rate less than 60 bpm. Results: After controlling for possible confounders, there was a clear correlation (r) between heart rate and all-cause mortality in elderly women (r=0.25, P=.0003). The correlation in women was observed using the three different methods for measuring heart rate. Heart rate was associated with all-cause and cardiovascular mortality. There was no relationship between heart rate and level of exercise or smoking status. In multiple regression analysis, the increased risk of death in the women was independent of previous cardiovascular or cerebrovascular disease, hypertension, anemia, congestive heart failure, smoking, and level of exercise or activities of daily living (relative odds ratio (ROR)=3.37, 95% confidence interval (CI)=0.96,11.8). When women using beta-blockers were excluded, this relationship became even stronger (ROR=8.5, 95% CI=1.19,60.1). Conclusion: Elevated heart rate is related to increased mortality in elderly women, thus representing a simple index of general health status in this population. Elevated heart rate did not predict mortality in elderly men. [source] Cardiac and coronary function in the Langendorff-perfused mouse heart modelEXPERIMENTAL PHYSIOLOGY, Issue 1 2009Melissa E. Reichelt The Langendorff mouse heart model is widely employed in studies of myocardial function and responses to injury (e.g. ischaemia). Nonetheless, marked variability exists in its preparation and functional properties. We examined the impact of early growth (8, 16, 20 and 24 weeks), sex, perfusion fluid [Ca2+] and pacing rate on contractile function and responses to 20 min ischaemia followed by 45 min reperfusion. We also assessed the impact of strain, and tested the utility of the model in studying coronary function. Under normoxic conditions, hearts from 8-week-old male C57BL/6 mice (2 mm free perfusate [Ca2+], 420 beats min,1) exhibited 145 ± 2 mmHg left ventricular developed pressure (LVDP). Force development declined by ,15% (126 ± 5 mmHg) with a reduction in free [Ca2+] to 1.35 mm, and by 25% (108 ± 3 mmHg) with increased pacing to 600 beats min,1. While elevated heart rate failed to modify ischaemic outcome, the lower [Ca2+] significantly improved contractile recovery (by >30%). We detected minimal sex-dependent differences in normoxic function between 8 and 24 weeks, although age modified contractile function in males (increased LVDP at 24 versus 8 weeks) but not females. Both male and female hearts exhibited age-related reductions in ischaemic tolerance, with a significant decline in recovery evident at 16 weeks in males and later, at 20,24 weeks, in females (versus recoveries in hearts at 8 weeks). Strain also modified tolerance to ischaemia, with similar responses in hearts from C57BL/6, 129/sv, Quackenbush Swiss and FVBN mice, but substantially greater tolerance in BALB/c hearts. In terms of vascular function, baseline coronary flow (20,25 ml min,1 g,1) was 50,60% of maximally dilated flows, and coronary reactive and functional hyperaemic responses were pronounced (up to 4-fold elevations in flow in hearts lacking ventricular balloons). These data indicate that attention to age (and sex) of mice will reduce variability in contractile function and ischaemic responses. Even small differences in perfusion fluid [Ca2+] also significantly modify tolerance to ischaemia (whereas modest shifts in heart rate do not impact). Ischaemic responses are additionally strain dependent, with BALB/c hearts displaying greatest intrinsic tolerance. Finally, the model is applicable to the study of vascular reactivity, providing large responses and excellent reproducibility. [source] Effects of moderate acute isovolaemic haemodilution on myocardial function in patients undergoing coronary surgery under volatile inhalational anaesthesiaANAESTHESIA, Issue 3 2009S. G. De Hert Summary When myocardial oxygen demand is increased by elevated heart rate in patients undergoing coronary artery surgery under total intravenous anaesthesia, acute isovolaemic haemodilution may be associated with a deterioration of cardiac function. We investigated the effects of acute isovolaemic haemodilution during volatile inhalational anaesthesia. Forty patients undergoing coronary surgery were randomly assigned to two groups according to the rate of atrioventricular pacing (Group 70 at 70.min,1 and Group 90 at 90.min,1). While paced at the fixed heart rate, acute isovolaemic haemodilution was performed before the start of cardiopulmonary bypass. In both groups mean (SD) stroke volume increased with haemodilution (from 65 (9) to 83 (10) ml.min,1 (p < 0.01) in Group 70 and from 65 (9) to 81 (9) ml.min,1 (p < 0.01) in Group 90) as a result of a decrease in systemic vascular resistance (from 1175 (231) to 869 (164) dynes.s.cm,5 (p < 0.01) and from 1060 (185) to 849 (146) dynes.s.cm,5 (p < 0.01), respectively) and an increase in end-diastolic volume (from 1049 (234) to 1405 (211) ml (p < 0.01) and from 1078 (106) to 1438 (246) ml (p < 0.01), respectively). Left ventricular pressure-derived data remained unchanged with acute isovolaemic haemodilution in both groups. [source] Heart rate-lowering and -regulating effects of once-daily sustained-release diltiazemCLINICAL CARDIOLOGY, Issue 1 2001William E. Boden M.D. Abstract Background: Epidemiologic evidence suggests that an elevated heart rate (HR) is an adverse and independent prognostic factor in arterial hypertension and other cardiovascular diseases. Although diltiazem is characterized as an HR-lowering calcium antagonist, no studies have quantified the magnitude of HR changes in patients with angina or hypertension. Hypothesis: The study was undertaken to explore the magnitude of proportional HR reduction at varying levels of resting HR with the sustained-release formulation of diltiazem (SR diltiazem) at the usual clinical doses of 200 or 300 mg once daily. Methods: This meta-analysis was conducted on six comparative double-blind studies including 771 patients with angina or hypertension in which SR diltiazem 200,300 mg once daily was compared either with placebo or with other agents known not to influence HR (angiotensin-converting enzyme inhibitors, diuretics). Sustained-release diltiazem decreases elevated baseline HR, with an increasing effect at higher initial rates. Results: Multiple comparisons by baseline HR category showed a significant difference between both groups for baseline HR of 74,84 beats/min and , 85 beats/min (p = 0.001). Sustained-release diltiazem had no significant HR-decreasing effect on baseline HR , 74 beats/min but appears to have a genuine regulating effect on HR: it reduces tachycardia without inducing excessive bradycardia. These findings are in contrast to those with dihydropyridine calcium antagonists, which tend to increase HR and have been associated with an adverse outcome in acute cardiovascular conditions. At the same time, there is evidence to suggest that HR-lowering calcium-channel blockers decrease cardiovascular event rates following myocardial infarction. Conclusion: When calcium antagonists are indicated for use in patients with angina or hypertension, an HR-lowering agent, that is, diltiazem rather than dihydropyridine, should be recommended. [source] | ||||||||||