Reduced Work Performance Research Articles

Exercise performance in tetralogy of Fallot after intracardiac repair

We evaluated 99 male and 36 female patients with tetralogy of Fallot 1 year or more after intracardiac repair (ICR) in 279 exercise studies between 1968 and 1979. Sixty tetralogy patients were studied serially two to nine times at 12 to 18 month intervals. Work performance and heart rate response to cycle exercise with stepwise loading (100 kg-m/min increments) were (1) related to clinical, pre- and post-ICR cardiac catheterization, surgical, and anatomic information and (2) compared to results obtained in 221 male and 157 female normal control volunteers. On the average, male tetralogy patients were shorter and weighed less than control subjects, but female tetralogy patients as a group showed no growth impairment. Many tetralogy patients had slower resting, submaximal, and final exercise heart rates than did control subjects. Work performance averaged 82% +/- 21% of predicted in male patients and 86% +/- 29% in female patients. Serial studies showed no significant changes in work performance in the majority of tetralogy patients for up to 10 years. Best work performance was found in nine varsity athletes (99% +/- 22%) and 21 patients with primar ICR (94% +/- 23%). Statistical analysis demonstrated a significant relationship between reduced work performance and residual disease, notably cardiac enlargement, increased peak systolic right ventricular pressure, pulmonic valve incompetence (PI), residual ventricular septal defect (VSD), pulmonary hypertension, and cardiac rhythm disturbances. However, in individuals work performance cannot be predicted reliably from the presence of these lesions and should therefore be measured. We conclude that exercise testing is a useful adjunct to the clinical and hemodynamic evaluation of post-ICR tetralogy.

Stress-coping strategies among medical residents in Saudi Arabia: A cross-sectional national study.

Objectives:Maladaptive stress-coping strategies have been linked to reduced quality of life, psychiatric disorders, and reduced work performance among residents or physicians. This study aimed to examine stress-coping strategies among medical residents in Saudi Arabia and their association with stress levels and important personal characteristics.Methods:This cross-sectional study was conducted between May and October 2012. Residents of different specialties were recruited from a national database. Stress-coping strategies were assessed using the 28-item brief coping scale (BCS), while stress was assessed using the perceived stress scale (PSS).Results:Nine hundred seventeen residents completed both BCS and PSS assessments. Almost 55% of participants were males, 88% were Saudi, 58% were married, and 15% had positive history of psychiatric disorders. The adaptive stress-coping strategy with the highest score was religion, followed by planning, acceptance, and active coping. The maladaptive stress-coping strategy with the highest score was self-blame, followed by self-distraction, and venting. Maladaptive stress-coping strategies were associated with high stress level, female gender, and history of psychiatric disorders. Stress-coping strategies were not correlated/associated with age, presence of major medical illnesses, or stress management education/training.Conclusion:Adaptive stress-coping strategies were more frequently used among a sample of residents in Saudi Arabia than maladaptive stress-coping strategies, with higher use of religion in coping than previously reported. To avoid potential negative impact on resident well-being, future studies among residents should aim to identify the type of stress management program that most positively impacts stress-coping skills.

Myocardial function and metabolism in idiopathic endomyocardial disease and subacute pericarditis, with a comparison of findings in cor pulmonale: An aid in differential diagnosis

Studies are described which provide information that may be of value in differentiating patients with constrictive pericarditis from those with idiopathic endomyocardial disease. Restrictive factors in and around the myocardium are thought to be responsible for the reduced work performance and cardiac failure in idiopathic endomyocardial disease and subacute constrictive pericarditis. Since the studies revealed evidence of hypoxia in patients with constrictive pericarditis, data from patients with cor pulmonale in failure were used to clarify the effect of hypoxia on the contraction mechanism and metabolism of the left ventricle when there was no associated mechanical impediment. A change in myocardial compliance is thought to account for the abbreviated t-dp/dt in idiopathic endomyocardial disease, and a reduced inflow and splinting action and a contributory hypoxia in subacute pericarditis are thought to account for the prolongation of t-dp/dt. In patients with idiopathic endomyocardial disease the heart had a normal oxidative metabolic pattern, whereas in patients with subacute pericarditis or cor pulmonale, the heart tended toward an anaerobic metabolic pattern. Present findings support the view that the redox potential gradient, (ΔE h) based on pyruvate/lactate ratios, reflects the oxidative state of heart muscle fibers. The heart failure of idiopathic endomyocardial disease is probably related to mechanical events consequent to surrounding fibrosis rather than to metabolic factors or to a disturbance in coronary blood flow. In subacute pericarditis coronary blood flow may become impaired because of a restrictive effect of the thickened pericardium, which results in an additional metabolic response to hypoxia of the myocardium.

Work performance of the isolated perfused beating heart in the hereditary myocardiopathy of the Syrian hamster.

The work performance of the isolated beating heart of control Syrian hamsters and hamsters suffering from an inbred myocardiopathy was studied in a system using a myographic differential force transducer. A stretch force of either 3.75 or 8.75 g was applied to the hearts. Myocardial metabolism of pyruvate-3- 14 C and palmitate-1- 14 C was studied with and without a stretch force. A definite reduction in work performance of the myopathic heart could be demonstrated. Peak height of contraction, tension-time index, tension time per minute and heart rate were significantly lower. The progressive myocardial fiber lengthening, caused by the stretch force, was less in the myopathic hearts. No difference was observed between the uptake and oxidation of pyruvate-3- 14 C and palmitate-1- 14 C by control and myopathic hearts. The presence of a stretch force affected metabolism of both hearts in a similar manner. Two mechanisms for explaining the reduction in work performance by the myopathic heart were observed, namely, a reduction in heart rate and a relative inability of the myopathic muscle fibers to lengthen. The depressed mechanical performance could not be related directly with altered substrate metabolism or with reduction in total muscle mass.

EFFECTS OF MICROBIAL FLORA ON CARDIAC OUTPUT AND OTHER ELEMENTS OF BLOOD CIRCULATION.

SummaryCardiac output in young adult germfree rats was found to be approximately 30% lower than in conventional controls. Concomitantly, signs of mild hemoconcentration were observed in the germfree group, which may be linked to changed water balance in these animals. The reduced work performance of the heart indicated in the germfree group is associated with the absence of a microbial flora.