Cardiac action potential to fail, then the heart could continue to beat, albeit at a lower rate (AVN= 40-60 beats per minute, purkinje fibres = 20-40 beats per minute). These pacemakers will keep a patient alive until the emergency team arrives. An example of premature ventricular contraction, is the classic athletic heart syndrome. Sustained training of athletes causes a cardiac adaptation where the resting SAN rate is lower (sometimes around 40 beats per minute). This can lead to atrioventricular block, where the signal from the SAN is impaired in its path to the ventricles. This leads to uncoordinated contractions between the atria and
Cardiac glycoside heart rate without significant changes in heart rate or blood pressure; this quality allows it to be widely used medicinally in the treatment of cardiac arrhythmias. Cardiac glycosides have long served as the main medical treatment to congestive heart failure and cardiac arrhythmia, due to their effects of increasing the force of muscle contraction while reducing heart rate. Heart failure is characterized by an inability to pump enough blood to support the body, possibly due to a decrease in the volume of the blood or its contractile force. Treatments for the condition thus focus on lowering blood pressure, so that