Cardiac pacemaker discharge at about 40-60 beats per minute, and are called the "secondary pacemaker". Further down the electrical conducting system of the heart is the Bundle of His. The left and right branches of this bundle, and the Purkinje fibres, will also produce a spontaneous action potential at a rate of 30-40 beats per minute, so if the SA and AV node both fail to function, these cells can become pacemakers. It is important to realize that these cells will be initiating action potentials and contraction at a much lower rate than the primary or secondary pacemaker cells. The SA node
"What Is This Heart?" of 69, based on 32 reviews, which indicates "generally favorable reviews". Ian Cohen of Pitchfork Media gave a very positive review of the album stating, ""What Is This Heart?" makes you initially susceptible and vulnerable, and that’s risky when modern discourse seeks metaphorical blood, allowing people to disclose more than ever without actually revealing anything. So make no mistake, the title of this album is a challenge as well, as How to Dress Well’s modern masterpiece is conducted with the most eternal transparency—Krell asks “what is this heart” and lets you look right into his own." "What Is This Heart?"