Is it possible to suffer a cardiac arrest despite having a pacemaker?

A pacemaker is implanted for various heart diseases. It is a valuable support especially for diseases of the excitation conduction system, as it can maintain a regular beat rhythm in the heart. The pacemaker works as follows: Via a probe, the pacemaker can measure the excitation given by the heart.

Based on its measurement results, the pacemaker produces weak currents that compensate for any possible failures of the sinus node (=natural pacemaker of the heart, center of excitation formation) and thus adjust the rhythm and keep it steady. In case of cardiac arrest, the pacemaker can detect that no more excitation is coming from the heart. In this case the pacemaker automatically stops working. Therefore, a cardiac arrest can occur despite the use of a pacemaker.

Cardiac arrest during surgery

A cardiac arrest can occur as a complication of surgery. This usually affects people who already have one or more heart diseases, i.e. where the heart has been damaged. Major surgery is also associated with an increased risk of cardiac arrest.In complex operations performed on the heart, it may be necessary to induce an artificial cardiac arrest for a short time.

For this purpose, drugs are used that reduce the activity of the heart to a minimum. Instead, the function of the heart is taken over by a heart-lung machine, which keeps the circulation intact. This technique makes open heart surgery possible. After the end of the operation, the drugs are removed so that the heart can begin beating again on its own.

Why does a cardiac arrest lead to a coma?

The heart is the pump of the human blood circulation. This is why a cardiac arrest also results in a standstill of the blood in the circulation. In the body, the blood has above all a transport function: it transports nutrients from the intestines and liver to all organs, it is enriched with oxygen in the lungs to release it again in the organs.

In addition, it transports the waste products generated by metabolism in the organs to the liver and kidneys, where the products can be excreted. In case of cardiac arrest, this transport is interrupted. This means that waste products accumulate in the organs while the organs are not supplied with new nutrients or oxygen.

The brain, as one of our most important organs, is particularly dependent on a regular supply of oxygen. Already after a few seconds without blood flow and without oxygen, processes in the brain are regulated differently, so that affected persons faint. If the brain continues to be undersupplied, various cells in the brain will die. In order for the brain to consume less energy, it virtually switches to a resting state. In doing so, consciousness is switched off, so to speak, and a coma results.