Non-pharmacological heart failure therapies : evaluation by ventricular pressure-volume loops

In this thesis, we evaluated the acute and chronic hemodynamic effects of non-pharmacological heart failure therapies. In particular, the effects of surgical treatment and biventricular pacing therapy were investigated by left ventricular pressure-volume loop analyses. We demonstrated that restrictive mitral annuloplasty effectively restored mitral leaflet coaptation without inducing significant acute changes in ventricular function. This indicates that this procedure can be safely applied in patients with heart failure. Surgical ventricular restoration was shown to achieve acute normalisation of left ventricular volumes, improved systolic function, and decreased left ventricular wall stress and mechanical dyssynchrony. At the expense of a higher diastolic pressure resulting from altered diastolic properties, stroke work and cardiac output were not importantly altered, but mechanical efficiency was significantly improved. Chronically, surgical therapy resulted in improved clinical status evidenced by improved NYHA class, quality of life score, and 6-min walking distance. Left ventricular function and dyssynchrony remained significantly improved at 6 months follow-up. In addition, we observed a decrease in pulmonary artery pressure, right ventricular reverse remodeling and reduced tricuspid regurgitation. Acute and chronic hemodynamic effects of cardiac resynchronization therapy (biventricular pacing) were demonstrated by pressure-volume loop analysis. Hemodynamic improvements, previously only shown in acute studies, were shown to be maintained at 6 months follow-up. In addition, ventricular-arterial coupling, mechanical efficiency, and chronotropic responses were improved. In conclusion, the acute and chronic hemodynamic effects of these non-pharmacological heart failure therapies were demonstrated by ventricular pressure-volume analysis. These findings provide insight in the underlying mechanisms and help to explain improved functional status achieved with these therapies.UBL - phd migration 201

ABCB1 genotypes and haplotypes in patients with dementia and age-matched non-demented control patients

Amyloid β is an in vitro substrate for P-glycoprotein (P-gp), an efflux pump at the blood brain barrier (BBB). The Multi Drug Resistance (ABCB1) gene, encoding for P-gp, is highly polymorphic and this may result in a changed function of P-gp and may possibly interfere with the pathogenesis of Alzheimer's disease. This study investigates to what extent ABCB1 Single Nucleotide Polymorphisms (SNPs; C1236T in exon 12, G2677T/A in exon 21 and C3435T in exon 26) and inferred haplotypes exist in an elderly population and if these SNPs and haplotypes differ between patients with dementia and age-matched non-demented control patients. ABCB1 genotype, allele and haplotype frequencies were neither significantly different between patients with dementia and age-matched controls, nor between subgroups of different types of dementia nor age-matched controls. This study shows ABCB1 genotype frequencies to be comparable with described younger populations. To our knowledge this is the first study on ABCB1 genotypes in dementia. ABCB1 genotypes are presently not useful as a biomarker for dementia, as they were not significantly different between demented patients and age-matched control subjects

3D Real-Time Echocardiography Combined with Mini Pressure Wire Generate Reliable Pressure-Volume Loops in Small Hearts

BACKGROUND: Pressure-volume loops (PVL) provide vital information regarding ventricular performance and pathophysiology in cardiac disease. Unfortunately, acquisition of PVL by conductance technology is not feasible in neonates and small children due to the available human catheter size and resulting invasiveness. The aim of the study was to validate the accuracy of PVL in small hearts using volume data obtained by real-time three-dimensional echocardiography (3DE) and simultaneously acquired pressure data. METHODS: In 17 piglets (weight range: 3.6–8.0 kg) left ventricular PVL were generated by 3DE and simultaneous recordings of ventricular pressure using a mini pressure wire (PVL3D). PVL3D were compared to conductance catheter measurements (PVLCond) under various hemodynamic conditions (baseline, alpha-adrenergic stimulation with phenylephrine, beta-adrenoreceptor-blockage using esmolol). In order to validate the accuracy of 3D volumetric data, cardiac magnetic resonance imaging (CMR) was performed in another 8 piglets. RESULTS: Correlation between CMR- and 3DE-derived volumes was good (enddiastolic volume: mean bias -0.03ml ±1.34ml). Computation of PVL3D in small hearts was feasible and comparable to results obtained by conductance technology. Bland-Altman analysis showed a low bias between PVL3D and PVLCond. Systolic and diastolic parameters were closely associated (Intraclass-Correlation Coefficient for: systolic myocardial elastance 0.95, arterial elastance 0.93, diastolic relaxation constant tau 0.90, indexed end-diastolic volume 0.98). Hemodynamic changes under different conditions were well detected by both methods (ICC 0.82 to 0.98). Inter- and intra-observer coefficients of variation were below 5% for all parameters. CONCLUSIONS: PVL3D generated from 3DE combined with mini pressure wire represent a novel, feasible and reliable method to assess different hemodynamic conditions of cardiac function in hearts comparable to neonate and infant size. This methodology may be integrated into clinical practice and cardiac catheterization programs and has the capability to contribute to clinical decision making even in small hearts

Closing the Loop: Modelling of Heart Failure Progression from Health to End-Stage Using a Meta-Analysis of Left Ventricular Pressure-Volume Loops

Introduction The American Heart Association (AHA)/American College of Cardiology (ACC) guidelines for the classification of heart failure (HF) are descriptive but lack precise and objective measures which would assist in categorising such patients. Our aim was two fold, firstly to demonstrate quantitatively the progression of HF through each stage using a meta-analysis of existing left ventricular (LV) pressure-volume (PV) loop data and secondly use the LV PV loop data to create stage specific HF models. Methods and Results A literature search yielded 31 papers with PV data, representing over 200 patients in different stages of HF. The raw pressure and volume data were extracted from the papers using a digitising software package and the means were calculated. The data demonstrated that, as HF progressed, stroke volume (SV), ejection fraction (EF%) decreased while LV volumes increased. A 2-element lumped parameter model was employed to model the mean loops and the error was calculated between the loops, demonstrating close fit between the loops. The only parameter that was consistently and statistically different across all the stages was the elastance (Emax). Conclusions For the first time, the authors have created a visual and quantitative representation of the AHA/ACC stages of LVSD-HF, from normal to end-stage. The study demonstrates that robust, load-independent and reproducible parameters, such as elastance, can be used to categorise and model HF, complementing the existing classification. The modelled PV loops establish previously unknown physiological parameters for each AHA/ACC stage of LVSD-HF, such as LV elastance and highlight that it this parameter alone, in lumped parameter models, that determines the severity of HF. Such information will enable cardiovascular modellers with an interest in HF, to create more accurate models of the heart as it fails

Impact of a tailored program on the implementation of evidence-based recommendations for multimorbid patients with polypharmacy in primary care practices — results of a cluster-randomized controlled trial

Background: Multimorbid patients receiving polypharmacy represent a growing population at high risk for negative health outcomes. Tailoring is an approach of systematic intervention development taking account of previously identified determinants of practice. The aim of this study was to assess the effect of a tailored program to improve the implementation of three important processes of care for this patient group: (a) structured medication counseling including brown bag reviews, (b) the use of medication lists, and (c) structured medication reviews to reduce potentially inappropriate medication. Methods: We conducted a cluster-randomized controlled trial with a follow-up time of 9 months. Participants were general practitioners (GPs) organized in quality circles and participating in a GP-centered care contract of a German health insurance. Patients aged >50 years, suffering from at least 3 chronic diseases, receiving more than 4 drugs, and being at high risk for medication-related events according to the assessment of the treating GP were enrolled. The tailored program consisted of a workshop for GPs and health care assistants, educational materials and reminders for patients, and the elaboration of implementation action plans. The primary outcome was the change in the degree of implementation between baseline and follow-up, measured by a summary score of 10 indicators. The indicators were based on structured surveys with patients and GPs. Results: We analyzed the data of 21 GPs (10 - intervention group, 11 - control group) and 273 patients (130 - intervention group, 143 - control group). The increase in the degree of implementation was 4.2 percentage points (95% confidence interval: −0.3, 8.6) higher in the intervention group compared to the control group (p = 0.1). Two of the 10 indicators were significantly improved in the intervention group: medication counseling (p = 0.017) and brown bag review (p = 0.012). Secondary outcomes showed an effect on patients’ self-reported use of medication lists when buying drugs in the pharmacy (p = 0.03). Conclusions: The tailored program may improve implementation of medication counseling and brown bag review whereas the use of medication lists and medication reviews did not improve. No effect of the tailored program on the combined primary outcome could be substantiated. Due to limitations of the study, results have to be interpreted carefully. The factors facilitating and hindering successful implementation will be examined in a comprehensive process evaluation. Trial registration number ISRCTN34664024, assigned 14/08/201