Publications by authors named "Klaus K A Witte"

Symptomatic sustained ventricular tachycardia is a life threatening arrhythmia requiring prompt treatment. However, the risk associated with asymptomatic nonsustained ventricular tachycardia (NSVT) detected on routine permanent pacemaker (PPM) interrogation in patients with known cardiac conduction disease is unknown. Our aim is to determine if asymptomatic NSVT detected on PPM interrogation is associated with increased mortality.

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Introduction: Patients with right ventricular pacemakers are at increased risk of left ventricular systolic dysfunction (LVSD). We aimed to establish the prevalence, degree and associations of LVSD in patients with long-term right ventricular pacemakers listed for pulse generator replacement (PGR).

Methods: All patients listed for PGR at Leeds General Infirmary were invited to attend for an assessment during which we recorded medical history, symptomatic status, medical therapy, date and indication of first implantation, the percentage of right ventricular pacing (% RVP) and an echocardiogram.

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Background: Serum calcium (Ca) and inorganic phosphate (Pi) concentrations and calcium-phosphate product (CPP) levels are positively associated with worse outcomes in patients with chronic kidney disease, but there are few data for Pi or Ca and none for CPP in patients with chronic heart failure (CHF).

Methods: Unselected, consecutive patients with CHF (left ventricular ejection fraction, LVEF ≤45%) were enrolled in a prospective observational study for the occurrence of hospitalisation and mortality. Blood samples were collected at the time of recruitment and analysed immediately.

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Aims: Heart failure and left ventricular (LV) systolic dysfunction (LVSD) are common in patients with permanent pacemakers. The aim was to determine if cardiac resynchronization therapy (CRT) at the time of pulse generator replacement (PGR) is of benefit in patients with unavoidable RV pacing and LVSD.

Methods And Results: Fifty patients with unavoidable RV pacing, LVSD, and mild or no symptoms of heart failure, listed for PGR were randomized 1 : 1 to either standard RV-PGR (comparator) or CRT.

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Chronic heart failure (CHF) is a common condition, which despite major advances, is still characterized by high mortality (with sudden arrhythmic death a particular risk), poor quality of life due to exercise intolerance and frequent hospitalizations. Epidemiological studies suggest that populations with a high intake of marine polyunsaturated fatty acids (PUFAs or fish oils) have low levels of cardiovascular mortality. Animal and human studies of fish oil supplementation have demonstrated improved endothelial function and myocardial relaxation, reduced vascular tone and platelet aggregability, and a stabilization of myocyte excitability by prolongation of the refractory period.

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Background: In non-heart failure populations, dyspnoea reported by the patient as the reason for stopping an exercise test is associated with a worse prognosis than fatigue. Patients with chronic heart failure (CHF) have exercise limitation due to breathlessness or fatigue, but it is unclear whether one symptom confers an adverse prognosis over the other.

Methods: Consecutive CHF patients underwent exercise testing with metabolic gas exchange.

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Chronic heart failure (CHF) is common, and increases in incidence and prevalence with age. There are compelling data demonstrating reduced mortality and hospitalizations with adrenergic blockade in older patients with CHF. Despite this, many older patients remain undertreated.

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Background: Changes within skeletal muscle, including augmentation of its capacity to elicit reflex increases in both efferent muscle sympathetic nerve activity (MSNA) and ventilation during work, contribute significantly to exercise intolerance in heart failure (HF). Previously, we demonstrated that peak oxygen uptake (pVO(2)) in HF relates inversely to MSNA at rest and during exercise.

Objective: To test the hypothesis that there is an independent positive relationship between resting MSNA and the ratio of ventilation to carbon dioxide output during exercise (VE/VCO(2)) that is augmented in HF.

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Introduction: Cachexia is common in chronic heart failure (CHF) and may be due to a combination of reduced appetite, and increased metabolic rate due to immune activation. This hypermetabolism, with an increase in acute phase protein turnover, also seen in cancer cachexia, might contribute to weight loss seen in severe CHF. We investigated the rate of hepatic fibrinogen synthesis by measuring the rate of incorporation of deuterated phenylalanine into circulating plasma fibrinogen.

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Our aim was to determine the prevalence, morbidity, and mortality associated with the presence of significant renal artery stenosis (RAS) in patients with chronic heart failure (HF), and to explore the use of angiotensin-converting enzyme (ACE) inhibitors and diuretics in this population during a 3-year follow-up period. We identified 97 patients with significant renal dysfunction (RD, defined as a calculated glomerular filtration rate of <60 ml/min) and 38 patients without RD, with ejection fractions of <40%. A stenosis of >50% using magnetic resonance angiography of the renal arteries was used to define significant RAS.

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Background: No specific guidelines exist on how to manage renal dysfunction (RD) in patients with chronic heart failure (CHF).

Aims: To identify the proportion of patients with moderate to severe RD and CHF who showed an improvement in their renal function in response to a systematic management algorithm.

Methods: Stable patients with CHF and RD (defined by a serum creatinine (SCr) of >130 micromol/l (>1.

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Background: Beta-blockers are effective for the treatment of heart failure, but their mechanism of action is unresolved. Heart rate reduction may be a central mechanism or a troublesome side effect.

Methods: A randomized, double-blind, parallel group study comparing chronic higher-rate (80 pulses per minute) with lower-rate (60 pulses per minute) pacing in pacemaker-dependent patients with symptomatic left ventricular (LV) systolic dysfunction, receiving beta-blockers.

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Anemia and renal dysfunction (RD) are frequent complications seen in chronic heart failure (HF). However, the prevalence and interaction of these co-morbidities in a representative population of outpatients with chronic HF is poorly described. In this study, it was sought to determine the association between RD and anemia in patients with HF enrolled in a community-based HF program.

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Background: Cardiac resynchronization therapy (CRT) reduces symptoms and mortality in patients with left bundle branch block (LBBB) and severe chronic heart failure. There are few data demonstrating the effects of CRT on contemporary dyssynchrony variables in patients with advanced heart failure who have been chronically paced from the right ventricle (RV).

Methods And Results: We reviewed baseline and follow-up clinical and echocardiographic data on patients receiving CRT in a single centre.

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Background: The heart transforms structurally and functionally with age but the nature and magnitude of reported changes appear inconsistent. This study was designed to assess left ventricular (LV) morphology, global and longitudinal function in healthy older men and women using cardiac magnetic resonance (CMR).

Methods: Ninety-five healthy subjects (age 62+/-16 years, range 22-91 years) underwent breath-hold cine CMR.

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Aims: To determine the prevalence and incidence of renal dysfunction (RD) in patients with chronic heart failure (CHF), to identify contributory factors and predictors of worsening renal function (WRF), and to explore the relationship between RD and mortality.

Methods And Results: Prospective data on 1216 patients with CHF were analysed. The glomerular filtration rate (GFR) was used to determine renal function, and WRF was defined as an increase in serum creatinine of >26.

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Recent studies have demonstrated the inefficacy of nutritional supplements containing various combinations of vitamins and minerals for otherwise healthy elderly people and patients with ischemic heart disease. However, patients with chronic heart failure (CHF) have, up until recently, been excluded from such studies. CHF has a high mortality and morbidity and patients are often elderly with poor general nutrition and high levels of micronutrient deficiency.

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Background: The kinetics of oxygen and carbon dioxide at the onset of and recovery from exercise are slowed in patients with chronic heart failure (CHF). The aim of the present study was to establish whether the kinetics of O2 are influenced by the work rate.

Methods: Thirteen CHF patients and 12 control subjects underwent bicycle-based peak exercise testing with metabolic gas exchange analysis.

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