Metabolic cost of unloading pedalling in different groups of patients with pulmonary hypertension and volunteers.

Recently, the parameter internal work (IW) has been introduced as change in oxygen uptake (VO2) between resting and unloading workload in cardiopulmonary exercise testing (CPET). The proportional IW (PIW) was defined as IW divided by VO2 at peak exercise. A second option is to calculate the PIW based on the workload [PIW (Watt)] by considering the aerobic efficiency. The aim of our study was to investigate whether IW and PIW differ between patients with and without pulmonary hypertension and healthy controls. Our study population consisted of 580 patients and 354 healthy controls derived from the Study of Health in Pomerania. The PIW was slightly lower in patients (14.2%) than in healthy controls (14.9%; p = 0.030), but the PIW (Watt) was higher in patients (18.0%) than in the healthy controls (15.9%; p = 0.001). Such a difference was also observed, when considering only the submaximal workload up to the VAT (19.8% in patients and 15.1% in healthy controls; p < 0.001). Since the PIW (Watt) values were higher in patients with pulmonary hypertension, this marker may serve as a useful CPET parameter in clinical practice. In contrast to most of the currently used CPET parameters, the PIW does not require a maximal workload for the patient. Further studies are needed to validate the prognostic significance of the PIW.

The Other Side of the RAAS: Aldosterone Improves Migration of Cardiac Progenitor Cells.

Stem cell therapy is a promising new option for patients suffering from heart failure. Though many clinical studies show encouraging results, little is known about the signals which cause stem cells to home to diseased but not to healthy hearts. We hypothesized that aldosterone as one of the main players of heart failure functions as an attractant for progenitor cells and stimulates their migration. Stem cell antigen-1 (Sca-1) positive cells were isolated from the hearts of wild type FVB mice via magnetic cell sorting. The migration rate of the cells was determined using aldosterone as an attractant in a modified Boyden chamber (n = 5). Aldosterone led to a dose dependent increase in migration rate and this effect could be prevented by adding its blocker eplerenone. The mineralocorticoid receptor could be detected on Sca-1+ cells via western blot and immunofluorescence. Therefore, aldosterone seems to play a role in stem cell migration and there the effect is most likely mediated by the mineralocorticoid receptor.

Influence of smoking and obesity on alveolar-arterial gas pressure differences and dead space ventilation at rest and peak exercise in healthy men and women.

BACKGROUND AND AIMS: Besides exercise intolerance, the assessment of ventilatory and perfusion adequacy allows additional insights in the disease pathophysiology in many cardiovascular or pulmonary diseases. Valid measurements of dead space/tidal volume ratios (VD/VT), arterial (a') - end-tidal (et) carbon dioxide (CO2) and oxygen (O2) pressure differences (p(a'-et)CO2) and (p(et-a')O2), and alveolar (A)-a' O2 pressure differences (p(A-a')O2) require using blood samples in addition to gas exchange analyses on a breath-by-breath-basis. Smoking and nutritional status are also important factors in defining disorders. Using a large healthy population we considered the impact of these factors to develop useful prediction equations. METHODS AND RESULTS: Incremental cycle exercise protocols were applied to apparently healthy volunteer adults who did not have structural heart disease or echocardiographic or lung function pathologies. Age, height, weight, and smoking were analysed for their influence on the target parameters in each gender. Reference values were determined by regression analyses. The final study sample consisted of 476 volunteers (190 female), aged 25-85 years. Smoking significantly influences p(A-a')O2 and p(a'-et)CO2 at rest and peak exercise, and VD/VT during exercise. Obesity influences upper limits of VD/VT, p(a'-et)CO2 and p(et-a')O2 at rest as well as p(A-a')O2 and p(et-a')O2 at exercise. Reference equations for never-smokers as well as for apparently healthy smokers considering influencing factors are given. CONCLUSION: Gender, age, height, weight, and smoking significantly influence gas exchange. Considering all of these factors this study provides a comprehensive set of reference equations derived from a large number of participants of a population-based study.

Comparison of rotational with conventional coronary angiography.

BACKGROUND: Patient radiation exposure and consumption of contrast medium are considered major risks of diagnostic coronary angiography (CA). Rotation of the C-arm during CA could provide similar diagnostic accuracy and lower radiation exposure and contrast medium consumption. METHODS: To compare feasibility, safety, diagnostic accuracy, patient radiation exposure, and consumption of contrast medium of rotational CA with the invasive standard technique, intraindividual comparisons of the results obtained by both techniques were performed in 235 patients with an indication for first-time elective CA. In addition to conventional angiography, we performed 2 isocentric radiographic coronary spins with cranial and caudal tilts by 20 degrees around the left coronary artery and 1 strict posteroanterior rotational spin around the right coronary artery. RESULTS: In 16 patients, rotational CA was not performed because of safety concerns. In a further 12 patients, image quality of rotational scans was considered inadequate. In the remaining 207 patients, both modes of CA were proven suitable for anonymized, separate analysis by 3 independent cardiologists. Intraindividual comparison of both CA modes revealed a high degree of diagnostic agreement (Cohen (K) >0.8 for all cardiologists and for each coronary segment). Contrast medium volume during rotational CA and conventional CA amounted to 31.9 +/- 4.5 mL versus 52.2 +/- 8.0 mL (P < .001) and patient radiation exposure amounted to 5.0 +/- 2.6 Gy × cm(2) versus 11.5 +/- 5.5 Gy × cm(2) (P < .001), respectively. CONCLUSIONS: Rotational CA represents a safe and feasible method in clinical routine. Whereas diagnostic accuracy is similar to the usual conventional mode, consumption of contrast medium and patient radiation exposure are significantly reduced.