There is evidence that certain types of cognitive activity are associated with sympathoadrenomedullary activity. It also seems likely that sympathoadrenomedullary activity promotes the development of atherosclerosis and may precipitate the clinical complications of ischemic heart disease (IHD), such as myocardial ischemia, myocardial infarction, and sudden death.

Recent advances in methodological techniques have made it possible for researchers to noninvasively quantify cardiac function during cognitive stress. There is convincing evidence that impedance cardiography is a safe and convenient way to obtain valid and reliable estimates of hemodynamic indices at rest and during exercise in healthy and clinical populations.

The purpose of this study was to describe left ventricular function during cognitive stress before and after coronary artery bypass grafting (CABG). Twenty-five men who underwent surgery at one institution in Florida were studied one day prior to surgery and five to seven days following surgery. Impedance cardiography and blood pressure measurements were used to document changes from baseline in heart rate (HR), stroke volume (SV), myocardial contractility, systolic blood pressure (SBP), and diastolic blood pressure (DBP) during the administration of the Stroop Color Word Test (SCWT). Cardiac output (CO) and total peripheral resistance (TPR) were mathematically derived.

The findings of this study were consistent with the theoretical relationship between cognitive stress and sympatho-adrenal activation. The administration of the SCWT resulted in significant increases from baseline in HR, myocardial contractility, SV, CO, SBP, and DBP. Large increases in myocardial contractility and SV following CABG were evidence that LVF during cognitive stress is improved following myocardial reperfusion and may be comparable to the left ventricular response documented in persons free of IHD.

In this study, TPR did not change from baseline during the SCWT prior to CABG (F = 1.49, p = 0.2347) but decreased significantly from baseline during the SCWT following CABG (F = 98.48, p = 0.0001). These findings suggest that afterload may increase during cognitive stress in persons with IHD. An increase in afterload in the presence of compromised coronary blood flow may place the person with IHD at risk for myocardial ischemia, myocardial infarction, and death. These findings also provide evidence that afterload may decrease during cognitive stress following myocardial reperfusion.