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At least 55 records · Page 3Linked to original sources
PubMed1979

Reduced heart rate response to exercise in ischemic heart disease: the fallacy of the target heart rate in exercise testing.

When exercise testing 159 patients with prior myocardial infarction, we identified 39 who were limited by fatigue. This group was all in sinus rhythm; none were taking drugs likely to impair the chronotropic response of the heart; none experienced chest pain or developed ischemic ECG changes. In 18 of this group, maximal heart rate achieved with exercise was 2SD or more below the age predicted value, and their heart rate response to exercise was reduced compared to that of the other 21 whose maximal exercise heart rates were within 2SD of age predicted values. A subgroup of 8 subjects with reduced exercise heart rates was studied before and after vagal blockade. In the 4 subjects whose infarction was inferior, the reduction in heart rate response was more profound and persisted after vagal blockade, suggesting either reduced pacemaker responsivness, due to ischemia or infarction, or autonomic imbalance as possible mechanisms. All 8 showed alinear increases in ventilation at higher power outputs and mean blood lactate postexercise was 7.5 mM/I without vagal blockade. Our findings suggest that a reduced heart rate response to exercise, already shown to imply added coronary risk, may be subdivided aetiologically and possibly prognostically. The use of a "Target Heart Rate" in such patients offers no safety margin, and maximal exercise capacity will be grossly over-estimated if extrapolated from the submaximal heart rate response. A cardiovascular limitation to exercise may be detected by an alinear increase in ventilation.

Adult↗
PubMed1996

Heart rate reactivity and heart period variability throughout the first year after heart transplantation.

Heart rate reactivity to mental stress is substantially blunted early after heart transplantation, suggesting that the loss of neural modulation limits the cardiovascular response to mental stress. We tested whether reactivity to mental stress recovers during the first year after heart transplantation. Hemodynamic and respiratory responses to mental arithmetic challenge were studied in 20 heart transplant recipients 3, 6, and 12 months after surgery. A normal comparison group was studied at equivalent intervals. Heart rate reactivity to mental arithmetic was significantly reduced in the cardiac transplant group compared to the normal subjects. This effect persisted up to 1 year after transplantation. Heart period variability in the heart transplant recipients was minimal in all three test sessions. The findings suggest that no functional reinnervation or other compensatory adaptation occurs up to 1 year after heart transplantation.

Female↗
PubMed2004

Heart to Heart: a computerized decision aid for assessment of coronary heart disease risk and the impact of risk-reduction interventions for primary prevention.

Heart to Heart is a computer-based decision aid for patients and providers that provides personalized, evidence-based information about coronary heart disease (CHD) risk and potential risk-reducing interventions. To develop Heart to Heart, the authors used Framing-ham risk equations and systematic reviews of risk-reducing interventions. The Web version was programmed using PHP: Hypertext Processor, a Web-based programming language, and has separate interfaces for providers and patients. The authors subsequently developed a modified version for personal digital assistants. Heart to Heart uses information about a patient's CHD risk factors (age, gender, total and high-density lipoprotein cholesterol levels, diabetes, smoking, systolic blood pressure, and left ventricular hypertrophy) to calculate risk of total CHD events over 5 or 10 years. Patients and providers can then examine the effect of introducing one or more risk-reducing interventions (aspirin, lipid-lowering drug therapy, antihypertensive medication, or smoking cessation) on the patient's CHD risk. Future research will be directed to determining whether Heart to Heart can improve utilization of effective CHD risk-reducing interventions.

Adult↗
PubMed2002

[Persistence of oxidative stress after heart transplantation: a comparative study of patients with heart transplant versus chronic stable heart failure].

INTRODUCTION AND OBJECTIVE: Chronic heart failure (CHF) is associated with oxidative stress. Heart transplantation, an important therapeutic alternative in these patients, could reduce oxidative stress by improving cardiac function. Our aim was to evaluate post-heart transplantation oxidative stress. PATIENTS AND METHOD: We studied three experimental groups: a) heart transplant recipients without evidence of rejection (n = 11); b) NYHA class III CHF patients (n = 19), and c) healthy control subjects (n = 14). Oxidative stress was assessed by measuring plasma malondialdehyde levels (MDA), and determining the enzymatic activities of glutathione peroxidase (GSH-Px), catalase (CAT), and superoxide dismutase (SOD). RESULTS: The demographic characteristics of the three groups were similar. Mean time from transplantation was 20.0 4.8 months. Mean MDA plasma levels in heart transplantation and CHF patients were significantly higher than in normal subjects (3.35 0.8; 3.27 1.7 y 0.9 0.3 microM, respectively). GSH-Px activity increased after transplantation compared to control subjects (0.40 0.06 and 0.33 0.05 U/g Hb, respectively), but not the CHF group. A significant decrease in SOD activity was found in the heart transplant vs. CHF group (0.44 0.1 vs. 0.87 0.6 U/mg Hb). There were no differences in CAT values between heart transplant and CHF patients. CONCLUSION: These findings demonstrated the presence of permanent oxidative stress in patients who have undergone heart transplantation, characterized by an increase in MDA and a decrease in SOD activity, despite an increase in GSH-Px activity.

Adult↗
PubMed1999

Auxiliary total artificial heart: A compact electromechanical artificial heart working simultaneously with the natural heart.

Leading international institutions are designing and developing various types of ventricular assist devices (VAD) and total artificial hearts (TAH). Some of the commercially available pulsatile VADs are not readily implantable into the thoracic cavity of smaller size patients because of size limitation. The majority of the TAH dimensions requires the removal of the patients' native heart. A miniaturized artificial heart, the auxiliary total artificial heart (ATAH), is being developed in these authors' laboratories. This device is an electromechanically driven ATAH using a brushless direct current (DC) motor fixed in a center metallic piece. This pusher plate-type ATAH control is based on Frank-Starling's law. The beating frequency is regulated through the change of the left preload, assisting the native heart in obtaining adequate blood flow. With the miniaturization of this pump, the average sized patient can have the surgical implantation procedure in the right thoracic cavity without removing the native heart. The left and right stroke volumes are 35 and 32 ml, respectively. In vitro tests were conducted, and the performance curves demonstrate that the ATAH produces 5 L/min of cardiac output at 180 bpm (10 mmHg of left inlet mean pressure and 100 mm Hg of left outlet mean pressure). Taking into account that this ATAH is working along with the native heart, this output is more than satisfactory for such a device.

Blood Pressure↗
PubMed1997

Left ventricular remodeling with carvedilol in patients with congestive heart failure due to ischemic heart disease. Australia-New Zealand Heart Failure Research Collaborative Group.

OBJECTIVES: The aim of this study, a substudy of the Australia-New Zealand trial of carvedilol in patients with heart failure due to ischemic heart disease, was to determine the effects of this treatment on left ventricular size and function with the use of quantitative two-dimensional (2D) echocardiography. BACKGROUND: Beta-adrenergic blocking drugs have been shown to improve left ventricular ejection fraction in patients with heart failure due to either ischemic heart disease or idiopathic dilated cardiomyopathy. However, the effects of such treatment on left ventricular size remain uncertain. METHODS: One hundred twenty-three patients from 10 centers in New Zealand and Australia participated in the 2D echocardiographic substudy. Echocardiography was performed before randomization and was repeated after 6 and 12 months of treatment. Left ventricular end-diastolic and end-systolic volumes were measured from apical four- and two-chamber views with the use of a modified Simpson's rule method. RESULTS: After 12 months, heart rate was 8 beats/min lower in the carvedilol than in the placebo group, whereas left ventricular end-diastolic and end-systolic volumes were increased in the placebo group but reduced in the carvedilol group. At 12 months, left ventricular end-diastolic volume index was 14 ml/m2 less in the carvedilol than in the placebo group (p = 0.0015); left ventricular end-systolic volume index was 15.3 ml/m2 less (p = 0.0001), and left ventricular ejection fraction was 5.8% greater (p = 0.0015). CONCLUSIONS: In patients with heart failure due to ischemic heart disease, carvedilol therapy for 12 months reduced left ventricular volumes, increased left ventricular ejection fraction and prevented progressive left ventricular dilation. These changes demonstrate a beneficial effect of carvedilol on left ventricular remodeling in heart failure. The observed changes may explain in part the improved clinical outcomes produced by treatment with carvedilol.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

Change in heart rate and heart rate variability during treatment for depression in patients with coronary heart disease.

OBJECTIVE: Major depression is a common problem in patients with coronary heart disease (CHD) and is associated with an increased risk for cardiac morbidity and mortality. It is not known whether treating depression will improve medical prognosis in patients with CHD. Depression is also associated with elevated heart rate and reduced heart rate variability (HRV), which are known risk factors for cardiac morbidity and mortality that may explain the increased risk associated with depression. The purpose of this study was to determine whether treatment for depression with cognitive behavior therapy (CBT) is associated with decreased heart rate or increased HRV. METHODS: Thirty depressed patients with stable CHD, classified as either mildly or moderately to severely depressed, received up to 16 sessions of CBT. The 24-hour heart rate and HRV were measured in these patients and in 22 medically comparable nondepressed controls before and after treatment of the depressed patients. RESULTS: Average heart rate and daytime rMSSD (reflecting mostly parasympathetic activity) improved significantly in the severely depressed patients, but remained unchanged in the mildly depressed and the control patients. However, only rMSSD improved to a level comparable to the control patients. None of the remaining indices of HRV showed improvement. CONCLUSIONS: The results suggest that treating depression with CBT may reduce heart rate and increase short-term HRV. Thus, CBT may have a beneficial effect on a risk factor for mortality in depressed patients with coronary heart disease. A randomized, controlled study is needed to confirm these findings.

Cognitive Behavioral Therapy↗
PubMed1996

Autonomic interactions and chronotropic control of the heart: heart period versus heart rate.

Autonomic control of the heart varies more linearly with heart period than with rate. Relative linearity confers a greater independence of basal autonomic activation and heart period changes. Thus, heart period appears to be more appropriate for characterizing cardiac phenomena such as autonomic interactions that involve significant baseline shifts. Simulated and published empirical data were used to demonstrate the importance of the chronotropic metric for characterizing autonomic interactions. Simulations revealed a significant autonomic interaction when heart rate, but not heart period, was the chronotropic metric. Published heart rate data also show a substantial autonomic interaction, whereas heart period data do not. These findings suggest that the choice of chronotropic metric can overstate the extent of autonomic interactions on cardiac chronotropic function.

Autonomic Nervous System↗
PubMed1988

Comparison of the effects of neuropeptide Y (NPY) and 4-norleucine-NPY on isolated perfused rat hearts; effects of NPY on atrial and ventricular strips of rat heart and on rabbit heart mitochondria.

Isolated perfused rat hearts were used to compare the effects of the synthetic neuropeptide Y (NPY) and 4-norleucine-NPY on cardiac function. Each peptide exhibited both negative inotropic and chronotropic effects, and also caused coronary vasoconstriction leading to a reduction in coronary flow. A comparison of the IC50 values from dose-response curves using 10(-14) to 10(-7) M peptides (IC50 is the peptide concentration that produced a 50% decrease of the maximal effect) indicated that NPY was more potent as inhibitor of contractility and less potently inhibited coronary flow and heart rate, whereas 4-norleucine-NPY had more inhibitory influence on coronary flow and heart rate and less on cardiac contractility. This difference in potencies suggests that the inhibitory effects of NPY on contractility, coronary flow and heart rate may be independent of each other. Since NPY also decreased the contractile force of isolated left atrial and right ventricular strips of the rat heart, the coronary flow decrease cannot be the cause of the negative inotropy of isolated heart. Pretreatment of atrial and ventricular strips with NPY did not influence the positive inotropic effect produced by the cardiac glycoside ouabain indicating that sarcolemmal Na+, K+-ATPase was not involved in the inhibitory inotropic effect of NPY. Further studies towards elucidating the mechanism of the negative inotropy of cardiac muscles using isolated heart mitochondria revealed that NPY uncoupled oxidative phosphorylation and blocked mitochondrial calcium uptake; the former event fosters negative inotropy. Since these effects on mitochondria occurred at concentrations 100-fold higher than those required for negative inotropy, the two effects of NPY may not be related.

Animals↗
PubMed1996

Effects of beta-blockade with bisoprolol on heart rate variability in advanced heart failure: analysis of scatterplots of R-R intervals at selected heart rates.

The effect of beta-blockade on heart-rate variability was assessed at different heart rates in 52 patients with heart failure included in the randomized, placebo-controlled, Cardiac Insufficiency Bisoprolol Study (CIBIS). Scatterplots of R-R intervals display beat-to-beat variability by plotting each R-R interval against the preceding interval. Scatterplot dispersion at different R-R intervals provides a measure of beat-to-beat heart-rate variability at different heart rates. A 24-hour Holter tape was performed at baseline and after 2 months of treatment with bisoprolol or matched placebo. Geometric measurements of scatterplots were used to determine beat-to-beat dispersion for different R-R intervals. Bisoprolol and placebo groups were well matched at base-line. After 2 months of treatment, bisoprolol significantly increased beat-to-beat variability at the longest R-R intervals (p < 0.05); however, there was no change in scatterplot dispersion at the shortest R-R intervals. This suggests that beta-blockade increases parasympathetic or decreases sympathetic tone or both in heart failure patients only at the slowest heart rates.

Adrenergic beta-Antagonists↗
PubMed2001

Effects of tocopheryl quinone on the heart: model experiments with xanthine oxidase, heart mitochondria, and isolated perfused rat hearts.

It is generally accepted that the protection effect of biological tissues by vitamin E is due to its radical scavenging potency in membranes, thereby being transformed to a vitamin E radical. A deficiency of appropriate reductants, which recycle vitamin E radicals back to its antioxidative active form, causes an irreversible degradation of vitamin E leading to tocopheryl quinone (TQ). TQ-like compounds were shown to result from both vitamin E and corresponding hydrophilic analogues of this antioxidant in vitro. In vivo elevated concentrations of tocopheryl quinones were detected after oxidative stress and TQ supplementation as well. Quinones in general are known to be efficient one-electron donors and acceptors. Therefore the question arises whether TQ-like compounds can undergo redox-cycling in conjunction with redox-active enzymes in the heart, thereby producing harmful oxygen radicals, or whether these compounds exhibit antioxidant properties. In order to elucidate this question we focused our interest on the interaction of TQ and a corresponding short-chain homologue (TQ(0)) with xanthine oxidase and heart mitochondria. Furthermore, we tested the influence of TQ on the recovery of isolated perfused rat hearts after ischemia/reperfusion. Our experiments revealed that hydrophilic TQ(0) was univalently reduced by xanthine oxidase (XOD) yielding semiquinone radicals in the absence of oxygen. However, under aerobic conditions TQ(0) enhanced the O(2)(*)(-) radical output of XOD. In the mitochondrial respiratory chain TQ was shown to interact with high potential cytochrome b in the bc(1) complex specifically. In contrast to the system XOD/TQ(0), lipophilic TQ in submitochondrial particles decreased the O(2)(*)(-) radical release during regular respiration possibly due to its interaction with b-cytochromes in the mitochondrial respiratory chain. In isolated rat hearts perfused with liposomes containing lipophilic TQ, it was efficiently accumulated in the heart tissue. When hearts were subjected to conditions of ischemia/reperfusion, infusion of TQ prior to ischemia significantly improved the recovery of hemodynamic parameters. Our results demonstrate that TQ derivatives may induce pro-oxidative and antioxidative effects depending on the distribution of TQ derivatives in the heart tissue and the interacting redox system.

Animals↗
PubMed2000

Effects of carvedilol on left ventricular regional wall motion in patients with heart failure caused by ischemic heart disease. Australia-New Zealand Heart Failure Research Collaborative Group.

BACKGROUND: Beta-blocker therapy has been shown to improve left ventricular (LV) ejection fraction and reduce LV volumes in patients with heart failure caused by ischemic heart disease. However, the possible mechanisms of this improvement and the effects of such treatment on regional wall motion have not been established. In a substudy of the Australia-New Zealand trial of carvedilol in patients with heart failure caused by ischemic heart disease, the effects of treatment on LV regional wall motion were assessed using 2-dimensional echocardiography. METHODS AND RESULTS: One hundred nineteen patients from 10 centers were included on this substudy. Patients were randomly assigned to treatment with carvedilol or placebo. Echocardiography was performed before randomization and after 6 and 12 months of treatment. LV regional wall motion was assessed using a semiquantitative scoring system. LV wall motion score index (WMSI) was reduced from 2.40 to 2.29 after 6 and 12 months in the carvedilol group and remained unchanged in the placebo group (2-tailed P = .005, carvedilol vs placebo). The percentage of myocardium with normal function also significantly improved with carvedilol treatment. CONCLUSIONS: Carvedilol improved LV regional WMSI in patients with heart failure caused by ischemic heart disease. These results indicate a mechanism by which beta-blocker therapy may benefit patients with heart failure and are consistent with an intrinsic improvement in LV function after treatment with carvedilol.

Adrenergic beta-Antagonists↗
PubMed2004

Restoration of heart rate turbulence by titrated beta-blocker therapy in patients with advanced congestive heart failure: positive correlation with enhanced vagal modulation of heart rate.

INTRODUCTION: Heart rate turbulence (HRT) is a powerful novel predictor for cardiovascular mortality. Chronic congestive heart failure is associated with abnormal HRT. Whether antiadrenergic beta-blocker therapy can restore control of HRT in patients with chronic congestive heart failure is unknown. METHODS AND RESULTS: A 24-hour Holter ECG recording was obtained before and 1 and 3 months after titrated addition of atenolol therapy in 10 consecutive patients with advanced congestive heart failure. Two parameters derived from HRT, turbulence slope (TS) and turbulence onset (TO), and time- and frequency-domain heart rate variability (HRV) parameters (SDNN, RMSSD, VLF, LF, HF) from 24-hour ECG were compared before and after beta-blocker therapy, together with the same parameters in age-matched normal control. Results showed that TS (3.1 +/- 2.2 vs 6.2 +/- 3.0; P = 0.001) and all HRV parameters were increased after 3 months of atenolol treatment. No changes in TO were evident (0.6 +/- 0.5 vs -0.2 +/- 1.3; P = 0.13). The improvement of TS and the vagally mediated parameters of mean R-R interval, RMSSD, and the HF component of HRV were positively correlated. CONCLUSION: Abnormal HRT caused by chronic congestive heart failure can be restored by beta-blocker therapy. The evolution of TS was positively correlated with measures of vagal modulation of heart rate.

Adrenergic beta-Antagonists↗
PubMed1997

Randomised, placebo-controlled trial of carvedilol in patients with congestive heart failure due to ischaemic heart disease. Australia/New Zealand Heart Failure Research Collaborative Group.

BACKGROUND: In patients with heart failure, beta-blocker therapy improves left-ventricular function after 3-6 months of treatment, but effects of such treatment on symptoms and exercise performance are inconsistent, and the longer-term effects on death and other serious clinical events remain uncertain. We have investigated these issues in a double-blind, placebo-controlled, randomised trial of the beta-adrenergic blocker carvedilol (which also has alpha 1-blocking properties). METHODS: 415 patients with chronic stable heart failure were randomly assigned treatment with carvedilol (207) or matching placebo (208). At baseline, 6 months, and 12 months, we measured left-ventricular ejection fraction, left-ventricular dimensions, treadmill exercise duration, 6 min walk distance, New York Heart Association (NYHA) class, and specific activity scale (SAS) score. Double-blind follow-up continued for an average of 19 months, during which all deaths, hospital admissions, and episodes of worsening heart failure were documented. FINDINGS: After 12 months, left-ventricular ejection fraction had increased by 5.3% (2p < 0.0001) and end-diastolic and end-systolic dimensions had decreased by 1.7 mm (2p = 0.06) and 3.2 mm (2p = 0.001), respectively, in the carvedilol group compared with the placebo group. During the same period that were no clear changes in treadmill exercise duration, 6 min walk distance, NYHA class, or SAS score. After 19 months, the frequency of episodes of worsening heart failure was similar in the carvedilol and placebo groups (82 vs 75; relative risk 1.12 [95% Cl 0.82-1.53]) but the rate of death or hospital admission was lower in the carvedilol group than in the placebo group (104 vs 131; relative risk 0.74 [0.57-0.95]). INTERPRETATION: The beneficial effects of carvedilol on left-ventricular function and size were maintained for at least a year after the start of treatment, but carvedilol had no effect on exercise performance, symptoms, or episodes of worsening heart failure. There was an overall reduction in events resulting in death or hospital admission, and a year of treatment with carvedilol resulted in the avoidance of one such serious event among every 12-13 (SE 5) of these patients with chronic stable heart failure.

Adrenergic beta-Antagonists↗
PubMed1999

Reduction in heart failure events by the addition of a clinical pharmacist to the heart failure management team: results of the Pharmacist in Heart Failure Assessment Recommendation and Monitoring (PHARM) Study.

BACKGROUND: The multidisciplinary approach to managing heart failure has been shown to improve outcomes. The role of a clinical pharmacist in treating heart failure has not been evaluated. METHODS: One hundred eighty-one patients with heart failure and left ventricular dysfunction (ejection fraction <45) undergoing evaluation in clinic were randomized to an intervention or a control group. Patients in the intervention group received clinical pharmacist evaluation, which included medication evaluation, therapeutic recommendations to the attending physician, patient education, and follow-up telemonitoring. The control group received usual care. The primary end point was combined all-cause mortality and heart failure clinical events. All clinical events were adjudicated by a blinded end point committee. RESULTS: Baseline characteristics were similar except for slightly higher age in the intervention group. Median follow-up was 6 months. All-cause mortality and heart failure events were significantly lower in the intervention group compared with the control group (4 vs 16; P= .005). In addition, patients in the intervention group received higher angiotensin-converting enzyme inhibitor doses as reflected by the median fraction of target reached (25th and 75th percentiles), 1.0 (0.5 and 1) and 0.5 (0.1875 and 1) in the intervention and control groups, respectively (P<.001). The use of other vasodilators in angiotensin-converting enzyme inhibitor-intolerant patients was higher in the intervention group (75% vs 26%; P= .02). CONCLUSIONS: Outcomes in heart failure can be improved with a clinical pharmacist as a member of the multidisciplinary heart failure team. This observation may be due to higher doses of angiotensin-converting enzyme inhibitors and/or closer follow-up.

Aged↗