Using of spectral analysis of heart rate variability for increasing reliability of bicycle ergometry results

The aim was to study the suitability of the heart rate variability (HRV) spectral parameters for evaluations of bicycle ergometry results in coronary heart disease (CHD) patients. Methods. Our study included 243 male CHD patients aged 49±8 years. The coronary atherosclerosis was assessed by coronary angiography. The results of bicycle ergometry, Doppler echocardio-graphy and HRV spectral analysis were also analyzed. The duration of each stage of bicycle ergometry was 3 min, the initial load value was 25 W. Dynamic load continued until the patient had reached 75% of heart rate from his maximal age level. The maximal level of load achieved (i.e. load tolerance) was taken into consideration. We calculated sensitivity (Se), specificity (Sp), likelihood ratios of positive (LR+) and negative (LR-) bicycle ergometry results. Results. All patients had similar clinical characteristics. LR+ become maximal under the moderate load tolerance. LR- are maximal in the CHD patients with high load tolerance. Thus, the excessiveness of false-negative results of bicycle ergometry is in CHD patients with high load tolerance. Reliability of results of bicycle ergometry increased under using assessments of low-frequency (LF) range power of HRV spectrum. Conclusions. Thus,the using of LF range power of HRV spectrum increases reliability of bicycle ergometry (or other load tests) results in CHD patients.

Coronary artery occlusion after arterial switch operation in an asymptomatic 15-year-old boy

A 15-year-old boy with transposition of the great arteries(TGA) and neonatal arterial switch operation(ASO) presented with complete occlusion of the left main coronary artery(LMCA). Intra-operatively, an intramural left coronary artery was identified. Therefore, since age 7 years he had a series of screening exercise stress tests. At 13 years old, he had 3 to 4 mm ST segment depression in the infero-lateral leads without symptoms. This progressed to 4.2 mm inferior ST segment depression at 15 years old with normal stress echocardiogram. Sestamibi myocardial perfusion scan and cardiac magnetic resonance imaging was inconclusive. Therefore, a coronary angiogram was obtained which showed complete occlusion of the LMCA with ample collateralization from the right coronary artery system. This was later confirmed on a computed tomogram(CT) angiogram, obtained in preparation of coronary artery bypass grafting. The case illustrates the difficulty of detecting coronary artery stenosis and occlusion in young patients with rich collateralization. Coronary CT angiogram and conventional angiography were the best imaging modalities to detect coronary anomalies in this adolescent with surgically corrected TGA. Screening CT angiography may be warranted for TGA patients, particularly for those with known coronary anomalies.

The Influence of Sampling Site on Blood Lactate Response to Steady State Exercise

In sports sciences, blood lactate is commonly measured for performance testing or setting exercise intensity. Differences in measuring lactate concentration over time and across sampling sites during constant exercise are unknown. We aimed to compare blood lactate concentration across sampling sites during constant exercise. Eight participants performed three bouts of 20-min steady-state cycle exercise, consisting of 45, 60, and 75% of peak oxygen uptake (V . O2peak). Blood lactate levels were measured simultaneously from the fingertip and earlobe every 5 min during exercise. The time course analysis revealed that lactate level in the fingertip was significantly higher than in the earlobe at either work intensity (P < 0.05). A significant interaction effect (site x time) was observed at 60% V O2peak (P < 0.001), which indicated that the difference in samples across sampling sites decreased over time. The levels in the fingertip samples were higher at 5 min (P < 0.05);this difference was not noted after 10 min. Similarly, the fingertip values were significantly higher until 10 min (P < 0.05), but not after 15 min at 75% V O2peak. These findings suggest that the sampling site may affect the time course of change in lactate value under a constant workload.

Validation of VO_2Peakand performance using a SciFit^TMArm Ergometer

For individuals with lower extremity injury or disability, upper body exercise provides a mechanism of functional mobility training, car-diovascular fitness, as well as a means for clinical fitness assessment. However, the validity of fitness assessment relies on the efficacy of di-agnostic tools and measures in order to provide meaningful data to clinicians. The purpose of this investigation was to determine if the SciFitTMPro II Arm Ergometer, a widely available upper body ergometer (UBE), is a reliable device for the determination of VO2Peak in fit able-bodied swimmers. Eight trained male swimmers (28 ± 9 yrs) performed two incremental protocols VO2Peak consisting of a 4-min warm-up at 15 W followed by 2 min at 50 W and progressing 10 W every 2 min until volitional exhaustion. There was a linear relationship between workload and VO2 in all trials (R = 0.96;p ≤ 0.01) while Cronbach’s alpha for test-retest reliability for VO2 was 0.98. In conclusion, the UBE is an accurate and reliable device for determination of VO2Peak in trained swimmers, and further may be a viable alternative trainingVO2Peak injured athlete.