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Biomedical subjects

R Hambrecht

Publications and source records attributed to R Hambrecht.

At least 19 recordsLinked to original sources
PubMed2005

[Effects of physical training of chronic cardiac insuffciency].

During the last ten years,the traditional dogma "physical rest" for patients with chronic cardiac insufficiency (CCI) has been increasingly abandoned. Studies on the effects of low intensity physical endurance training for patients with stable CCI showed the following effects after 12 months: Decrease in the heart size and a slight improvement in the EF, reduction of the systemic vascular resistance during rest and during stress through improvement of the endothelial function, increase in the physical performance by 12 to 26%, reduction of local inflammation and improvement of the oxidative metabolism in skeletal muscles, an end to muscle atrophy and reduction of the total mortality. Training programs for patients with chronic cardiac insufficiency today represent an established auxiliary therapy for CCI with prognostic relevance.

Exercise↗
PubMed2005

[Physical exercise in older patients with chronic heart failure].

Maximal exercise capacity undergoes a steady decline after the age of 30 by approximately 10 % per decade. As a consequence of this development older people > 65 years of age suffer from the exercise limitation caused by age-associated cardiac, vascular and skeletal muscle changes. These physiologic alterations make older people especially vulnerable for the cardiovascular and peripheral alterations associated with chronic heart failure (CHF). These changes are not phenomenologically different from age-associated changes. Physical activity plays an important role for regaining a considerable part of vasomotor function, skeletal muscle contractility, and cardiac reserve. Up to now there are no prospective trials comparing the effects of physical training between older and younger patients with CHF. However, smaller observational studies indicate that elderly patients benefit equally well from training interventions with regard to functional improvements in proportion to their lower baseline values. In an aging population training aims at maintaining skeletal muscle force and muscle mass as well as locomotor coordination. Ultimately, the goal is to reduce the substantial morbidity among elderly CHF patients which constitute 79 % of all hospital admissions for heart failure.

Aged↗
PubMed2004

[The stakes of force perseverance training and muscle structure training in rehabilitation. Recommendations of the German Federation for Prevention and Rehabilitation of Heart-Circulatory Diseases e.v].

While aerobic endurance training has been a substantial part of international recommendations for cardiac rehabilitation during the last 30 years, there is still a rather reserved attitude of the medical community to resistance exercise in this field. Careful recommendations for resistance exercise in cardiac patients was only published a few years ago. It has been taken for granted that strength exercise elicits a substantial increase in blood pressure and thus imposes, especially in cardiac patients, a risk of potentially fatal cardiovascular complications. Results of the latest studies show that the existing recommended overcaution is not justified. Strength exercise can indeed result in extreme increases of blood pressure, but this is not the case for all loads of this kind. The actual blood pressure response to strength exercise depends on the isometric component, the exercise intensity (load or resistance used), muscle mass activated, the number of repetitions in the set and/or the duration of the contraction as well as involvement of Valsalva maneuver. Intra arterially performed blood pressure measurements during resistance exercise in patients with heart disease showed that strength training carried out at low intensities (40-60% of MVC) and with high numbers of repetitions (15-20) only evokes a moderate increase of blood pressure comparable with blood pressure measures induced by moderate endurance training. If used properly and performed accurately, individually dosed, medically supervised and controlled through experienced sport therapists, a dynamic resistance exercise is-at least for a certain group of patients-not associated with higher risks than an aerobic endurance training and can in addition to endurance training improve muscle force and endurance, have a positive influence on cardiovascular function, metabolism, cardiovascular risk factors as well as psychosocial well-being and overall quality of life. However, with respect to currently available data, resistance exercise cannot be generally recommended for all groups of patients. The appropriate kind and execution of training is highly dependent on current clinical status, cardiac capacity as well as possible accompanying diseases of the patient. Most of the studies carried out up to date included small samples of middle-aged male patients with almost normal levels of aerobic endurance performance and good left ventricular function. Data is missing for risk groups, older patients and women. Therefore, an integration of dynamic resistance exercises in cardiac rehabilitation can only be recommended without hesitation for CHD patients with high physical capacity (good myocardial function, revascularized). Since patients with myocardial ischemia and/or low left ventricular functioning might develop wall motion disturbances and/or dangerous ventricular arrhythmia when performing resistance exercises, prevalence of the following conditions is recommend: moderate to high LV-function, high physical performance (>5-6 metabolic equivalents= >1.4 watts/kg body weight) in absence of angina pectoris symptoms or ST-depression, by maintained current medication. In the proposed recommendations, a classification of risks for resistance training in cardiac rehabilitation is being made based on current data and is complemented by specific recommendations for particular groups of patients and detailed guidelines for setup and completion of the therapy program.

Blood Pressure↗
PubMed2004

Recommendations for resistance exercise in cardiac rehabilitation. Recommendations of the German Federation for Cardiovascular Prevention and Rehabilitation.

Aerobic endurance training has been an integral component of the international recommendations for cardiac rehabilitation for more than 30 years. Notwithstanding, only in recent years have recommendations for a dynamic resistance-training program been cautiously put forward. The perceived increased risk of cardiovascular complications related to blood pressure elevations are the primary concern with resistance training in cardiac patients; recent studies however have demonstrated that this need not be a contraindication in all cardiac patients. While blood pressure certainly may rise excessively during resistance training, the actual rise depends on a variety of controllable factors including magnitude of the isometric component, the load intensity, the amount of muscle mass involved as well as the number of repetitions and/or the load duration. Intra-arterial blood pressure measurements in cardiac patients have demonstrated that that during low-intensity resistance training [40-60% maximum voluntary contraction (MVC)] with 15-20 repetitions, only modest elevations in blood pressure are revealed, similar to those seen during moderate endurance training. When properly implemented by an experienced exercise therapist, in specific patient groups an individually tailored, medically supervised dynamic resistance training program carries no inherent higher risk for the patient than aerobic endurance training. As an adjunct to endurance training, in selected patients, resistance training can increase muscle strength and endurance, as well as positively influence cardiovascular risk factors, metabolism, cardiovascular function, psychosocial well-being and quality of life. According to present data, resistance training is however not recommended for all patient groups. The appropriate training method and correct performance are highly dependent on each patient's clinical status, cardiac stress tolerance and possible comorbidities. Most studies have used middle-aged men of average normal aerobic performance capacity and with good left-ventricular (LV) function. Data are lacking for high-risk groups, women and older patients. With the current knowledge it is reasonable to include resistance training without any restraints as part of cardiac rehabilitation programs for coronary artery disease (CAD) patients with good cardiac performance capacity (i.e., revascularised and with good myocardial function). As patients with myocardial ischaemia and/or poor left ventricular function may develop wall motion disturbances and/or severe ventricular arrhythmias during resistance exercise, the following criteria are suggested for resistance training: moderate-to-good LV function, good cardiac performance capacity [>5-6 metabolic equivalents of oxygen consumption (METS)=1.4 watt/kg body weight], no symptoms of angina pectoris or ST segment depression under continued maintenance of the medical therapy. Based on available data, this article presents recommendations for risk stratification in cardiac rehabilitation programs with respect to the implementation of dynamic resistance training. Additional recommendations for specific patient groups and detailed directions showing how to structure and implement such therapy programs are presented as well.

Cardiac Rehabilitation↗
PubMed2003

Regular physical activity improves endothelial function in patients with coronary artery disease by increasing phosphorylation of endothelial nitric oxide synthase.

BACKGROUND: In stable coronary artery disease (CAD), exercise training has well-documented positive effects on arterial endothelial function. NO derived from endothelial NO synthase (eNOS) is regarded as a protective factor against atherosclerosis. The aim of the present study was to investigate the effects of exercise training on the endothelial function in relation to the expression of eNOS and Akt-dependent eNOS phosphorylation in the left internal mammary artery (LIMA) of patients with stable CAD. METHODS AND RESULTS: In 17 training patients (T) and 18 control patients (C), endothelium-dependent vasodilation and average peak flow velocity (APV) in response to acetylcholine were measured invasively at study beginning and after 4 weeks in the LIMA. In LIMA tissue sampled during bypass surgery, eNOS expression and content of pospho-eNOS-Ser1177, Akt, and phospho-Akt were determined by Western blot and quantitative reverse transcriptase-polymerase chain reaction. After exercise training, LIMA APV in response to acetylcholine was increased by 56+/-8% (from +48+/-8% at beginning to +104+/-11% after 4 weeks, P<0.001). Patients in T had a 2-fold higher eNOS protein expression (T 1.0+/-0.7 versus C 0.5+/-0.3 arbitrary units, P<0.05) and 4-fold higher eNOS Ser1177-phosphorylation levels in LIMA-endothelium (1.2+/-0.9 versus 0.3+/-0.2 arbitrary units, P<0.01). A linear correlation was confirmed between Akt phosphorylation and phospho-eNOS levels (R=0.80, P<0.05) and between phospho-eNOS and Delta APV (R=0.59, P<0.05). CONCLUSIONS: Exercise training in stable CAD leads to an improved agonist-mediated endothelium-dependent vasodilatory capacity. The change in acetylcholine-induced vasodilatation was closely related to a shear stress-induced/Akt-dependent phosphorylation of eNOS on Ser1177.

Acetylcholine↗
PubMed2003

[Drug therapy and adjuvant therapy in heart failure. Exercise training--more effective than digitalis?].

Physical training is known to have a favorable effect on the extracardiac causes of intolerance of exertion associated with cardiac insufficiency. Randomized studies have shown an improvement in the oxidative capacity of the skeletal muscles, to an attenuation of chronic inflammation, correction of endothelial dysfunction, and to normalization of the frequently pathological ventilation under effort. The result is an increase in the maximum oxygen uptake--depending on the study--of between 15% and 29% (average 2 ml/kg min). An old worry that physical training might lead to a worsening of hemodynamics was not confirmed. As a result of the positive effect of training on the neurohumoral system and the peripheral endothelial function the resistance of peripheral vessels was lowered and the burden on the left ventricle reduced. The results of initial long-term observational studies also reveal a reduction in mortality.

Cardiovascular Agents↗
PubMed2003

Secondary prevention through cardiac rehabilitation: position paper of the Working Group on Cardiac Rehabilitation and Exercise Physiology of the European Society of Cardiology.

The purpose of this statement is to provide specific recommendations in regard to evaluation and intervention in each of the core components of cardiac rehabilitation (CR) to assist CR staff in the design and development of their programmes; the statement should also assist health care providers, insurers, policy makers and consumers in the recognition of the comprehensive nature of such programmes. Those charged with responsibility for secondary prevention of cardiovascular disease, whether at European, at national or at individual centre level, need to consider where and how structured programmes of CR can be delivered to the large constituency of patients now considered eligible for CR.

Europe↗
PubMed2003

Physical activity for primary and secondary prevention. Position paper of the Working Group on Cardiac Rehabilitation and Exercise Physiology of the European Society of Cardiology.

There is now clear scientific evidence linking regular aerobic physical activity to a significant cardiovascular risk reduction, and a sedentary lifestyle is currently considered one of the five major risk factors for cardiovascular disease. In the European Union, available data seem to indicate that less than 50% of the citizens are involved in regular aerobic leisure-time and/or occupational physical activity, and that the observed increasing prevalence of obesity is associated with a sedentary lifestyle. It seems reasonable therefore to provide institutions, health services, and individuals with information able to implement effective strategies for the adoption of a physically active lifestyle and for helping people to effectively incorporate physical activity into their daily life both in the primary and the secondary prevention settings. This paper summarizes the available scientific evidence dealing with the relationship between physical activity and cardiovascular health in primary and secondary prevention, and focuses on the preventive effects of aerobic physical activity, whose health benefits have been extensively documented.

Cardiovascular Diseases↗
PubMed2002

Exercise training and endothelial dysfunction in coronary artery disease and chronic heart failure. From molecular biology to clinical benefits.

Endothelial dysfunction (ED) has been documented in patients with both coronary artery disease (CAD) and chronic heart failure (CHF)-being responsible for exercise-induced myocardial ischemia in the former and increased afterload in the latter. In the last two decades exercise training has assumed a major role in both cardiovascular disorders. In CAD exercise training has established positive effects on myocardial perfusion. Recently, exercise training has been shown to attenuate paradoxical vasoconstriction in CAD. The improved ED after training explains the improvement of myocardial perfusion in the absence of changes in baseline coronary artery diameter. Since ED has been identified as a predictor of coronary events exercise may contribute to long-term reductions of cardiovascular mortality. In CHF the increased peripheral vascular resistance - especially during exercise - is more important. ED contributes to the peripheral vasoconstriction. Training programs have shown to improve ED in CHF. A long-term study of hemodynamic effects of training in CHF revealed a significant reduction of total peripheral resistance (TPR) that after 6 months with a concomitant increase in stroke volume. In a subgroup analysis a significant correlation between changes in TPR and changes in peripheral ED was observed. Cell culture and animal experiments suggest that shear stress increases the endothelial L-arginine uptake, enhances NO synthase activity and expression, and upregulates the production of extracellular superoxide dismutase, which prevents premature NO breakdown. All these molecular effects converge on a reduction of myocardial ischemic events in CAD and a decrease of afterload in CHF.

Chronic Disease↗
PubMed2001

Reversal of cardiogenic shock by percutaneous left atrial-to-femoral arterial bypass assistance.

BACKGROUND: Recovery of myocardial function after revascularization of acutely occluded coronary arteries may require several days. During this critical time, patients in cardiogenic shock may have low output. A newly developed percutaneous left ventricular assist device (VAD) may offer effective treatment for these patients by providing active circulatory support. METHODS AND RESULTS: Between May 2000 and May 2001, VADs were implanted in 18 consecutive patients who had cardiogenic shock after myocardial infarction. The device was connected to the patient's circulation by insertion of a 21F venous cannula into the left atrium by transseptal puncture; blood was returned to the iliac artery through an arterial cannula. Mean duration of cardiac assistance was 4+/-3 days. Mean flow of the VAD was 3.2+/-0.6 L/min. Before support, cardiac index was 1.7+/-0.3 L/min per m(2) and improved to 2.4+/-0.6 L/min per m(2) (P<0.001). Mean blood pressure increased from 63+/-8 mm Hg to 80+/-9 mm Hg (P<0.001). Pulmonary capillary wedge pressure, central venous pressure, and pulmonary artery pressure were reduced from 21+/-4, 13+/-4, and 31+/-8 mm Hg to 14+/-4, 9+/-3, and 23+/-6 mm Hg (all P<0.001), respectively. Overall 30-day mortality rate was 44%. CONCLUSIONS: A newly developed VAD can be rapidly deployed in the catheterization laboratory setting. This device provides up to 4.0 L/min of assisted cardiac output, which may aid to revert cardiogenic shock. The left ventricle is unloaded by diverting blood from the left atrium to the systemic circulation, making recovery more likely after an ischemic event. The influence of this device on long-term prognosis warrants further investigation.

Adult↗
PubMed2001

Differentially expressed genes in L6 rat skeletal muscle myoblasts after incubation with inflammatory cytokines.

OBJECTIVE: The mechanism underlying exercise intolerance in chronic heart failure is still unclear. An increased concentration of inflammatory cytokines could be detected in the serum of patients with chronic heart failure (CHF) exhibiting a correlation with the severity of the disease. The variety of molecular alterations triggered by these cytokines in the skeletal muscle is almost unknown. The study was designed to analyze the differential gene expression in skeletal muscle myoblasts after stimulation with inflammatory cytokines. METHODS: L6 rat skeletal muscle myoblasts were incubated for 24 h with a combination of IL-1beta/IFN-gamma and the differential gene expression profile was determined by a PCR-based subtractive hybridization method. RESULTS: Out of 173 picked clones 141 different sequences could be identified. By comparison with Genebank, the identity of 73 genes (51.7%) could be confirmed, whereas the rest did not show a homology to any known gene. Some of the identified genes are known to be altered in patients with CHF. CONCLUSION: In summary, the results of this study provide information about changes in gene expression after exposure of skeletal muscle cells to inflammatory cytokines. This information may yield a new gene pool, worthwhile to be analyzed in skeletal muscle of patients with chronic heart failure.

Animals↗
PubMed2001

Exercise training in coronary artery disease and coronary vasomotion.

Exercise training has assumed a major role in cardiac rehabilitation, mostly because of its positive effects on myocardial perfusion in patients with coronary artery disease. The mechanisms involved in mediating this key effect have long been debated: both regression of coronary artery stenosis and improvement of collateralization have been suggested as potential adaptations. However, the comparatively minute changes in luminal diameter and myocardial contrast staining do not fully explain the significant changes in myocardial perfusion. During the last decade, endothelial dysfunction was identified as a trigger of myocardial ischemia. The impaired production of endothelium-derived nitric oxide (NO) in response to acetylcholine and flow leads to paradoxic vasoconstriction and exercise-induced ischemia. Recently, it was confirmed in humans that training attenuates paradoxic vasoconstriction in coronary artery disease and increases coronary blood flow in response to acetylcholine. Data from cell-culture and animal experiments suggest that shear stress acts as a stimulus for the endothelium to increase the transport capacity for L-arginine (the precursor molecule for NO), to enhance NO synthase activity and expression, and to increase the production of extracellular superoxide dismutase, which prevents premature breakdown of NO. Exercise also affects the microcirculation, where it sensitizes resistance arteries for the vasodilatory effects of adenosine. These novel findings provide a pathophysiological framework to explain the improvement of myocardial perfusion in the absence of changes in baseline coronary artery diameter. Because endothelial dysfunction has been identified as a predictor of coronary events, exercise may contribute to the long-term reduction of cardiovascular morbidity and mortality.

Animals↗
PubMed2001

Apoptosis in skeletal muscle.

Apoptosis is a physiological, conserved program of cellular suicide, characterized by nuclear condensation, DNA-fragmentation and release of mitochondrial cytochrome c into the cytoplasm. The apoptotic program is executed by a cascade of highly specific caspases. The occurrence and significance of apoptosis in multinucleated, differentiated cells, like skeletal muscle cells is discussed controversy in the current literature. In this review we will summarize the knowledge concerning the occurrence of apoptosis in certain diseases and the regulation of apoptosis in skeletal muscle.

Animals↗
PubMed2001

Effects of exercise training on vascular function and myocardial perfusion.

It has long been unclear how exercise training improves myocardial perfusion in patients with stable CAD. Regression of coronary atherosclerosis and collateral formation have been favorite theories; however, angiographic techniques have so far failed to document any significant increase in coronary collaterals at rest. Although net regression of stenotic lesions may be achieved in high-intensity exercise training, it is unlikely that it causes the significant improvement in myocardial perfusion that is seen much earlier than plaque regression. The novel tools to examine coronary endothelial function in vivo and in vitro have now made it clear that exercise training enhances myocardial perfusion by increasing both eNOS and ecSOD expression, which attenuates the premature breakdown of NO by ROS. These increases in local NO production and half-life improve endothelium-dependent vasodilation in response to flow or acetylcholine. These functional changes will occur rather rapidly after the initiation of an exercise training program, although no studies are available on their precise time course. Anatomic changes, such as augmentation of the capillary bed and slowing of the progression of coronary atherosclerosis, may require more extended periods of training (Fig. 4). Recently, first reports about a possible association between endothelial dysfunction and the frequency of clinical events has been documented. Further prospective studies are needed to establish whether endothelial dysfunction is just an indicator of plaque instability or an independent prognostic marker. If it turns out to be the latter, exercise training may be promoted from a symptomatic intervention to a preventive strategy with long-term prognostic benefits.

Animals↗
PubMed2001

Endothelial dysfunction in patients with chronic heart failure: systemic effects of lower-limb exercise training.

OBJECTIVES: We sought to analyze the systemic effects of lower-limb exercise training (ET) on radial artery endothelial function in patients with chronic heart failure (CHF). BACKGROUND: Local ET has the potential to improve local endothelial dysfunction in patients with CHF. However, it remains unclear whether the systemic effects can be achieved by local ET. METHODS: Twenty-two male patients with CHF were prospectively randomized to either ET on a bicycle ergometer (ET group, n = 11; left ventricular ejection fraction [LVEF] 26 +/- 3%) or an inactive control group (group C, n = 11; LVEF 24 +/- 2%). At the beginning of the study and after four weeks, endothelium-dependent and -independent vasodilation of the radial artery was determined by intra-arterial infusion of acetylcholine (ACh-7.5, 15 and 30 microg/min) and nitroglycerin (0.2 mg/min). The mean internal diameter (ID) of the radial artery was assessed using a high resolution ultrasound system (NIUS-02, Asulab Research Laboratories, Neuchâtel, Switzerland) with a 10-MHz probe. RESULTS: After four weeks of ET, patients showed a significant increase in the baseline-corrected mean ID in response to ACh (30 microg/min), from 33 +/- 10 to 127 +/- 25 microm (p < 0.001 vs. control group at four weeks). In the control group, the response to ACh (30 microg/min) remained unchanged. Endothelium-independent vasodilation was similar in both groups at the beginning of the study and at four weeks. In the training group, increases in agonist-mediated, endothelium-dependent vasodilation correlated to changes in functional work capacity (r = 0.63, p < 0.05). CONCLUSIONS: In patients with stable CHF, bicycle ergometer ET leads to a correction of endothelial dysfunction of the upper extremity, indicating a systemic effect of local ET on endothelial function.

Aged↗
PubMed2001

Diagnostic value of intraoperative swabs of heart valves in infective endocarditis.

BACKGROUND AND AIM OF THE STUDY: Intraoperative swabs of heart valves are obtained regularly from patients undergoing heart valve surgery for infective endocarditis (IE) in order to confirm the preoperative diagnosis and to adjust the antibiotic regimen. The study aim was to assess the diagnostic value of intraoperative swabs of heart valves in IE. METHODS: A total of 83 patients was referred for surgical treatment of active IE between October 1994 and May 1999. Preoperatively, microorganisms were isolated using a minimum of two positive blood cultures; results were compared with those obtained from intraoperative heart valve swab cultures. RESULTS: Preoperatively, 73 patients (88%) had a positive blood culture, and 10 (12%) had culture-negative endocarditis. The intraoperative swab confirmed the preoperative diagnosis in 31 cases (37%). Bacteria were isolated in three of the ten patients with preoperative culture-negative IE. Despite positive histopathological findings in seven patients, no microorganisms were cultured either pre- or intraoperatively. Among the remaining 42 patients (51%) with active IE, 25 valve cultures were sterile and 17 valve swabs were presumed to be contaminated. CONCLUSION: In patients with active IE in whom the causative agent could be isolated and identified before surgery, intraoperative valve swabs did not contribute further to patient management. In isolating contaminants, the risk of inappropriate modification of the antibiotic regimen is imminent. The diagnostic validity in culture-negative IE appears negligible.

Adolescent↗
PubMed2000

Myocardial ischemia during physical exercise in patients with stable coronary artery disease: predictability and prevention.

AIMS: We assessed whether exercise-induced myocardial ischemia during intensive group exercise sessions can be predicted in patients with coronary artery disease and stable angina pectoris. METHODS AND RESULTS: Twenty-three patients underwent cardiac catheterization, 201-thallium scintigraphy, and exercise testing prior to participation in group training sessions. Heart rates and myocardial ischemia were documented by Holter monitoring. The individual training heart rate was calculated as a percentage of the maximal heart rate achieved during symptom-limited exercise testing. Myocardial ischemia occurred significantly more often during group exercise sessions (15 of 23 patients) than during treadmill testing (4 of 23 patients, P<0.001). Maximal heart rate (145+/-23 vs. 134+/-21 beats/min, P<0.004) and maximal plasma lactate concentrations (6.0+/-2.9 vs. 4.3+/-2.0 mmol/l, P<0.05) were significantly higher than during symptom-limited exercise testing. Ischemic episodes occurred significantly more often during jogging than during competitive ball games or interval training. Myocardial ischemia occurred in patients who exceeded their individual target training heart rates (43 of 44 episodes; P<0.001). Duration of ischemic episodes did not correlate with any marker obtained at the beginning of the study. CONCLUSION: These data demonstrate that routine diagnostic procedures do not sufficiently identify patients at risk for exercise-induced myocardial ischemia. Ischemic events are only effectively prevented by choosing adequate types of exercise and, above all, by the strict adherence to individual target heart rates.

Coronary Angiography↗