Another risk factor identified by experts included condition that leads to changes in cardiac rhythm and/or electrical conduction, such as bradycardia, tachycardia, pacemaker displacement, blocking of transmission of the cardiac impulse, impulse transmission through abnormal pathways and abnormal spontaneous impulses. Accordingly, bradycardia without an associated increase in inotropism leads to a reduction in systolic output. Similarly,tachycardia caused by electrical stimulation of the sinus node determines the increase in frequency up to a certain limit, beyond which myocardial weaken-ing and a decrease in heart rate occur (Guyton and Hall, 2006).