Effect of mental challenge induced by movie clips on action potential duration in normal human subjects independent of heart rate

Abstract

Background: Mental stress and emotion have long been associated with ventricular arrhythmias and sudden death in animal models and humans. The effect of mental challenge on ventricular action potential duration (APD) in conscious healthy humans has not been reported.

Methods and results: Activation recovery intervals measured from unipolar electrograms as a surrogate for APD (n=19) were recorded from right and left ventricular endocardium during steady-state pacing, whilst subjects watched an emotionally charged film clip. To assess the possible modulating role of altered respiration on APD, the subjects then repeated the same breathing pattern they had during the stress, but without the movie clip. Hemodynamic parameters (mean, systolic, and diastolic blood pressure, and rate of pressure increase) and respiration rate increased during the stressful part of the film clip (P=0.001). APD decreased during the stressful parts of the film clip, for example, for global right ventricular activation recovery interval at end of film clip 193.8 ms (SD, 14) versus 198.0 ms (SD, 13) during the matched breathing control (end film left ventricle 199.8 ms [SD, 16] versus control 201.6 ms [SD, 15]; P=0.004). Respiration rate increased during the stressful part of the film clip (by 2 breaths per minute) and was well matched in the respective control period without any hemodynamic or activation recovery interval changes.

Conclusions: Our results document for the first time direct recordings of the effect of a mental challenge protocol on ventricular APD in conscious humans. The effect of mental challenge on APD was not secondary to emotionally induced altered respiration or heart rate.

Keywords: action potentials; arrhythmias, cardiac; stress, psychological.

Figure 1

Left hand panel: Intracardiac unipolar electrograms taken from the decapolar catheter (A) within the left ventricle during constant ventricular pacing (RV electrograms not shown in illustration). Top right – position of catheters on fluoroscopy (A – LV decapolar catheter, B Pacing catheter at RV apex, C – RV decapolar catheter). Bottom right – Illustration of Activation Recovery Interval calculated by the Wyatt method.

Figure 2

Change in Haemodynamics and Respiration Rate between movie and repeat breathing control. The mean change plus 95% Confidence Intervals is displayed. A: Systolic Blood Pressure. B: Diastolic Blood pressure. C: Rate of pressure development (RPD). D: Respiration Rate. The haemodynamic measurement changes significantly increase as the movie sequence becomes more stressful. The increase in respiration rate during the movie is well replicated in the repeat breathing control during mid and end sequence, but not the start.

Figure 3

Change in Activation recovery intervals (ARI) for left and right ventricles during the movie clip compared to the matched repeat breathing control. Data are displayed as mean difference compared to breathing control and 95% CI.

Figure 4

Change in Activation recovery intervals (ARI) illustrated by recording electrode. There is limited intra-ventricular variability (p=n/s). Values represent mean difference from control repeat breathing period to movie period, and 95% CI.