Impact of exercise capacity on myocardial high-energy phosphate metabolism.

31-Phosphorous magnetic resonance spectroscopy (31P MRS) is a unique tool to investigate IN VIVO high-energy phosphates (HEP) in the human heart. We hypothesized that physical capacity may be associated with myocardial HEP status. Healthy, male volunteers (n = 105, mean age 51 +/- 7 years) underwent bicycle ergometry with a stepwise increasing workload to determine maximal working capacity (MWC). Heart rate (HR) and blood pressure (BP) were measured continuously during exercise and 4 minutes of recovery. Further 31-Phosphorous 2-dimensional chemical shift imaging (31P 2D CSI) MRS was performed to assess myocardial HEP metabolism by determining phosphocreatinine to beta-ATP ratios (PCr/b-ATP) using a 1.5 tesla scanner. Volunteers with MWC > 230 Watt had significantly higher PCr/b-ATP ratios than those with MWC < 200 Watt (1.93 +/- 0.36 vs. 1.59 +/- 0.35; p < 0.001). Additionally, those with a recovery systolic (S)BP < 195 mmHg had significantly higher ratios than those with a recovery SBP > 195 mmHg (1.74 +/- 0.3 vs. 1.51 +/- 0.2; p < 0.05). We observed a linear correlation between the PCr/b-ATP ratio and MWC (r = 0.411; p < 0.001) and recovery SBP (r = - 0.290; p < 0.01). After statistical correction for age, these correlations remained significant. In this study, we observed a correlation of parameters of physical fitness determined by bicycle exercise testing and cardiac PCr/b-ATP ratios.

Risk factor profile for sudden cardiac death during mountain hiking.

Mountain hiking is associated with a death rate of about 4 deaths per 100,000 hikers annually. About 50 % of all fatalities during mountain hiking are sudden cardiac deaths (SCDs). But there are only few data available regarding risk factors and triggers associated with SCD during mountain hiking. Thus, a case-control analysis between persons who died suddenly during mountain hiking and randomly selected controls was carried out. Risk factor profiles of 179 males over the age of 34 who suffered SCD during mountain hiking were compared to those of 537 matched controls. Hikers who died suddenly during mountain hiking were much more likely to have had a prior MI (17% vs. 0.9%; p < 0.001), known coronary artery disease (CAD) without prior MI (17 % vs. 4%; p < 0.001), diabetes (6% vs. 1 %; p < 0.001), hypercholesterolemia (54 % vs. 20%; p < 0.001), and were less engaged in regular mountain sports activities (31% vs. 58%; p < 0.001) compared to hikers from the control group. Based on the reported relationship between traditional risk factors and coronary plaque morphology, acute plaque rupture with thrombus formation and subsequent lethal arrhythmias may be assumed to be a dominant mechanism precipitating SCD during hiking. In contrast, in skiers especially non-occlusive plaques may precipitate ischemia leading to an imbalance between oxygen demand and supply and subsequent lethal arrhythmias. As preventive measures recommended to hikers at risk, adaptation to regular mountain sports activities by an adequate training program and pharmacological interventions, e.g. lipid lowering drugs, aspirin, and beta-blockers, should be considered.

How to diagnose MSA early: the role of magnetic resonance imaging.

The clinical differentiation between Parkinson's disease (PD) and multiple system atrophy (MSA) remains a challenge for each neurologist. The use of different magnetic resonance imaging (MRI) techniques including conventional MRI, proton magnetic resonance spectroscopy (MRS), diffusion-weighted imaging (DWI), magnetization transfer imaging (MTI) and MR volumetry (MRV) offer the potential for objective criteria in the differential diagnosis of neurodegenerative parkinsonism. The aim of this article is to review the role of different MRI techniques in the differential diagnosis of PD and MSA.

Diffusion-weighted imaging discriminates progressive supranuclear palsy from PD, but not from the parkinson variant of multiple system atrophy.

BACKGROUND AND OBJECTIVE: The parkinson variant of multiple system atrophy (MSA-P) and progressive supranuclear palsy (PSP) present with atypical parkinsonism, which may be misdiagnosed as PD, particularly in early disease stages. It was previously shown that diffusion-weighted MRI (DWI) is a sensitive tool to discriminate MSA-P from PD based on increased apparent diffusion coefficients (ADCs) in the putamen. In this study DWI was evaluated in 10 patients with PSP compared with 13 patients with PD and 12 with MSA-P. METHODS: Disease was diagnosed according to established diagnostic criteria and groups were matched for age, disease duration, and Hoehn and Yahr "off" stage. Regional ADCs (rADCs) were determined in different brain regions including basal ganglia, gray matter, white matter, substantia nigra, and pons. RESULTS: In patients with PSP compared with those with PD, rADCs were significantly increased in putamen, globus pallidus, and caudate nucleus. Stepwise logistic regression analysis followed by receiver operating characteristics analysis identified an optimal cut-off value for putaminal rADC, discriminating PSP and PD with a sensitivity of 90% and a positive predictive value of 100%. DWI failed to discriminate PSP and MSA-P. CONCLUSIONS: These results show that DWI detects basal ganglia abnormalities in PSP patients within few years of disease onset, discriminating patients with PSP from those with PD, but not from those with MSA-P.

Diffusion-weighted MRI differentiates the Parkinson variant of multiple system atrophy from PD.

OBJECTIVE AND BACKGROUND: Routine MRI as well as MR volumetry and MRS have been shown to contribute to the differential diagnosis of the Parkinson variant of multiple system atrophy (MSA-P) and PD. However, it is currently unknown whether diffusion-weighted imaging (DWI) discriminates these disorders. METHODS: Ten patients with MSA-P (mean age, 64 years) were studied, 11 with PD (mean age, 64 years), and seven healthy volunteers (mean age, 59 years) matched for age and disease duration. Regional apparent diffusion coefficients (rADC) were determined in different brain regions including basal ganglia, gray matter, white matter, substantia nigra, and pons. RESULTS: Patients with MSA-P had higher putaminal rADC (median 0.791 x 10(3)/mm(2)/s) than both patients with PD (median 0.698 x 10(3)/mm(2)/s, p < 0.001) and healthy volunteers (median 0.727 x 10(3)/mm(2)/s, p < 0.001). There were no significant differences in putaminal rADC between patients with PD and healthy volunteers. Moreover, none of the putaminal rADC values in the PD and control group surpassed the lowest value in the MSA-P group. There were no significant group differences in the rADC values in other brain regions such as pons, substantia nigra, globus pallidus, caudate nucleus, thalamus, or gray and white matter. Putaminal rADC values correlated significantly with Unified PD Rating Scale OFF scores in patients with MSA as measured by the Spearman rank test. CONCLUSION: DWI, even if measured in the slice direction only, is able to discriminate MSA-P and both patients with PD and healthy volunteers on the basis of putaminal rADC values. The increased putaminal rADC values in Parkinson variant of multiple system atrophy are likely to reflect ongoing striatal degeneration, whereas most neuropathologic studies reveal intact striatum in PD. Diffusion-weighted imaging may represent a useful diagnostic tool that can provide additional support for a diagnosis of Parkinson variant of multiple system atrophy.