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1.  Long-Term Prognostic Value of Restitution Slope in Patients with Ischemic and Dilated Cardiomyopathies 
PLoS ONE  2013;8(1):e54768.
An action potential duration (APD) restitution curve with a steep slope ≥1 has been associated with increased susceptibility for malignant ventricular arrhythmias. We aimed to evaluate the “restitution hypothesis” and tested ventricular APD restitution slope as well as effective refractory period (ERP)/APD ratio for long-term prognostic value in patients with ischemic (ICM) or dilated cardiomyopathy (DCM).
Methodology/Principal Findings
Monophasic action potentials were recorded in patients with ICM (n = 32) and DCM (n = 42) undergoing routine programmed ventricular stimulation (PVS). Left ventricular ejection fraction was 32±7% and 28±9%, respectively. APD and ERP were measured at baseline stimulation (S1) and upon introduction of one to three extrastimuli (S2–S4). ERP/APD ratios and the APD restitution curve were calculated and the maximum restitution slope was determined. After a mean follow-up of 6.1±3.0 years, the combined end-point of mortality and and/or implantable cardioverter-defibrillator shock was not predicted by restitution slope or ERP/APD ratios. Comparing S2 vs. S3 vs. S4 extrastimuli for restitution slope (1.5±0.6 vs. 1.4±0.4 vs. 1.3±0.5; p = NS), additional extrastimuli did not lead to a steepening restitution slope. ERP/APD ratio decreased with additional extrastimuli (0.98±0.09 [S1] vs. 0.97±0.10 [S2] vs. 0.93±0.11 [S3]; p = 0.03 S1 vs. S3). Positive PVS was strongly predictive of outcome (p = 0.006).
Neither ventricular APD restitution slope nor ERP/APD ratios predict outcome in patients with ICM or DCM.
PMCID: PMC3548796  PMID: 23349967
2.  High Frequency of Tropheryma whipplei in Culture-Negative Endocarditis 
Journal of Clinical Microbiology  2012;50(2):216-222.
“Classical” Whipple's disease (cWD) is caused by Tropheryma whipplei and is characterized by arthropathy, weight loss, and diarrhea. T. whipplei infectious endocarditis (TWIE) is rarely reported, either in the context of cWD or as isolated TWIE without signs of systemic infection. The frequency of TWIE is unknown, and systematic studies are lacking. Here, we performed an observational cohort study on the incidence of T. whipplei infection in explanted heart valves in two German university centers. Cardiac valves from 1,135 patients were analyzed for bacterial infection using conventional culture techniques, PCR amplification of the bacterial 16S rRNA gene, and subsequent sequencing. T. whipplei-positive heart valves were confirmed by specific PCR, fluorescence in situ hybridization, immunohistochemistry, histological examination, and culture for T. whipplei. Bacterial endocarditis was diagnosed in 255 patients, with streptococci, staphylococci, and enterococci being the main pathogens. T. whipplei was the fourth most frequent pathogen, found in 16 (6.3%) cases, and clearly outnumbered Bartonella quintana, Coxiella burnetii, and members of the HACEK group (Haemophilus species, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae). In this cohort, T. whipplei was the most commonly found pathogen associated with culture-negative infective endocarditis.
PMCID: PMC3264169  PMID: 22135251
3.  Correlation of epicardial and systemic flow-mediated vasodilation in patients with atypical angina but no evidence of atherosclerotic disease 
The Canadian Journal of Cardiology  2007;23(13):1054-1060.
Atypical angina represents a diagnostic challenge and can be observed in the absence of significant coronary atherosclerosis. Endothelial dysfunction is a relevant marker of prognosis, considering cardiovascular events. The aim of the present study was to compare flow-mediated vasodilation (FMD) in systemic peripheral and epicardial coronary arteries. If noninvasive measurements of FMD in systemic arteries correlated with invasive measurements of coronary FMD, this may facilitate diagnostic approaches and determination of prognosis in patients with atypical angina in the future. Patients with atherosclerosis were excluded, because structural changes of coronary vessels may impair adequate comparison.
Endothelial function (ENF) of epicardial and systemic arteries was examined in 61 consecutive patients with atypical angina in whom significant atherosclerosis was excluded by coronary angiography. ENF of the epicardial arteries was examined during heart catheterization, measuring diameter changes of the proximal left anterior descending coronary artery (LAD) in response to reactive hyperemia, induced by locally administered adenosine via infusion catheter to the mid-segment of the LAD (coronary FMD [FMDc]). ENF of the radial artery was examined with high-resolution ultrasound, measuring peripheral FMD (FMDp) in response to reactive hyperemia induced by distal cuff occlusion. Endothelium-independent vasoreactivity to glycerol trinitrate was assessed.
In patients with atypical angina in the absence of atherosclerosis, there was a significant correlation in ENF between coronary and systemic arteries (r=0.437; P=0.001). The underlying disease was myocardial inflammation (Inf) in 48 patients, in whom the mean (± SD) ENF of epicardial (FMDc-Inf 3.40±5.55%) and systemic (FMDp-Inf 3.69±2.93%) arteries was significantly impaired (P<0.001), compared with 13 control (Co) patients who had normal myocardial biopsies (FMDc-Co 14.51±8.62%; FMDp-Co 7.69±3.42%). FMD of coronary (r=–0.353; P=0.005) and systemic (r=–0.542; P<0.001) arteries correlated significantly with myocardial inflammation and endothelial activation.
There was a significant correlation in FMD between coronary and systemic arteries in patients with atypical angina but without significant atherosclerosis. Inflammatory processes are associated with endothelial dysfunction of both vascular regions.
PMCID: PMC2651929  PMID: 17985007
Cardiomyopathy; Coronary circulation; Endothelium-dependent vasodilation; Flow-mediated vasodilation; Inflammation; Peripheral circulation
4.  Brucella endocarditis in prosthetic valves 
The Canadian Journal of Cardiology  2006;22(11):971-974.
Human brucellosis is a multiple organ disease that presents with fever and is most often transmitted via contaminated, unpasteurized goat milk and cheese. In chronic cases, focal complications (eg, spondylitis, neurobrucellosis and endocarditis) are frequently seen. Although the disease may be severely debilitating, the mortality rate is low. Fatal cases are often due to endocarditis. Because Brucella endocarditis is a rare complication (2% to 5%), therapeutic considerations are based on single-case experiences only. Therapy includes long-term antibiotic treatment using combinations of various antimicrobial drugs and surgical valve replacement when required. A case of Brucella endocarditis complicated by the infection of two valvular prostheses implanted after involvement of the mitral and aortic valve due to rheumatic fever is described. The patient was successfully treated by a medical and surgical approach. Therapeutic strategies in Brucella endocarditis are discussed in light of the current literature.
PMCID: PMC2570246  PMID: 16971982
Antimicrobial therapy; Brucella endocarditis; Prosthetic valves; Valve replacement
5.  Pseudo current density maps of electrophysiological heart, nerve or brain function and their physical basis 
In recent years the visualization of biomagnetic measurement data by so-called pseudo current density maps or Hosaka-Cohen (HC) transformations became popular.
The physical basis of these intuitive maps is clarified by means of analytically solvable problems.
Examples in magnetocardiography, magnetoencephalography and magnetoneurography demonstrate the usefulness of this method.
Hardware realizations of the HC-transformation and some similar transformations are discussed which could advantageously support cross-platform comparability of biomagnetic measurements.
PMCID: PMC1660567  PMID: 17040559

Results 1-5 (5)