Continuous, non-invasive measurement of the haemodynamic response to submaximal exercise in patients with diabetes mellitus: evidence of impaired cardiac reserve and peripheral vascular response

Abstract

Background:Reduced exercise capacity in diabetics has been attributed to limitations in cardiac function and microvascular dysfunction leading to impaired oxygen supply and nutritive perfusion to exercising muscles.Objective:To study changes in cardiac function and microvascular utilisation during exercise in diabetic individuals compared to age-matched controls.Methods:Diabetics with glycosylated haemoglobin (HbA1c) <8 (n = 31), diabetics with HbA1c ⩾8 (n = 38) and age-matched non-diabetic controls (n = 32) performed exercise at 50 W for 10 minutes followed by recovery, with continuous monitoring of cardiac function by impedance cardiography and regional flow and oxygen saturation by laser Doppler and white light spectroscopy.Results:In the diabetics, cardiac reserve during exercise and cardiac overshoot during recovery are significantly reduced because of reduction in capacity to increase stroke volume. Regional flow to the exercising muscle is reduced and there is also disproportionately greater desaturation of the regional flow. Abnormalities in cardiac function and regional perfusion are related to the severity of diabetes.Conclusion:Cardiac response to exercise is attenuated significantly in diabetic individuals. Simultaneously, there is impairment in the regional distribution. These changes could be the harbinger of reduced exercise capacity in diabetics.

Association of Exercise Intolerance in Type 2 Diabetes With Skeletal Muscle Blood Flow Reserve

“…Previous work in this field has investigated LV function and muscle blood flow during submaximal exercise (7,8,10,18). This contrasts with the current study, where cardiovascular reserve was based on measurements taken post-maximal exercise.…”

“…Indeed, blunting of muscle capillary blood flow (CBF) during forearm contractions is described in T2DM patients with microvascular complications (9) and unites with slowed or reduced flow reserve during submaximal exercise (7,10). These observations certainly argue for important roles for peripheral vascular sequelae; however, associations with maximal exercise capacity in T2DM-particularly relative to left ventricular (LV) dysfunctionare unknown.…”

Augmentation Index Immediately after Maximal Exercise in Patients with Type 2 Diabetes Mellitus

“…Furthermore, the independent association of central AIx reserve with cardiac index reserve indicates that reduced postexercise cenfral AIx in T2DM may reflect a cardiac rather than vascular contribution. Lower postexercise stroke volume and cardiac indices in T2DM may reflect subclinical LV systolic and/or diastolic dysfunction (11,14). Whether reduced postexercise central AIx in T2DM arises from systolic or diastolic dysfunction is difficult to discern, although the former is an improbable culprit because, consistent with previous work (31), no association was identified between postexercise measures of central AIx and ELVL a marker of LV contractility.…”

The Evolving Face of Heart Failure Associated with Elevated Cardio-Metabolic Risk Factors

“…Impedance cardiography can be used non-invasively to measure hemodynamic parameters to diagnose covert cases of CMCM. Experimental studies in diabetic patients measuring stroke volume and cardiac output by impedance cardiography at the time of rest and exercise suggest, compromise in cardiac reserve even in the absence of any clinical symptoms of heart failure (Joshi et al, 2010). Compromise in cardiac reserve was contributed to, by an inappropriate increase in stroke volume due to diastolic compromise exaggerated by increase in heart rate.…”

“…Using CPET for evaluation of limitation in cardiac functions in the patients with heart failure associated with metabolic disorder will not only evaluate dynamic response of heart to physiological stress but also peripheral component of hemodynamics which often coexists. Symptoms such as fatigue and disproportionate dyspnoea may be explained by inadequate and inappropriate vascular responsiveness (capillary recruitment) to demand generated by exercising skeletal muscles (Joshi et al, 2010). Maximal aerobic capacity (peak VO 2 ), Ve/VCO 2 and oxygen uptake efficiency slope (OUES) parameters obtained from CPET aids in early diagnosis of subtle pathology and helps in following the progression of the disease.…”