PhD defence R.K. (Rohit) Kharbanda

Summary:

Atrial fibrillation is a cardiac arrhythmia whose underlying mechanism is still partly unknown. Unravelling the normal heart rhythm (sinus rhythm) is essential to further unravel the mechanism of cardiac arrhythmias, such as atrial fibrillation. To understand and treat the pathophysiology, understanding the physiology is fundamental. This thesis describes the results of new techniques to map atrial electrical conduction in great detail. These unique measurements were made on the inner and outer layer of the atria. The electrical measurements have been performed in various groups of patients; children and adults with congenital heart defects and in people who have undergone bypass or heart valve surgery. The technique described and studies performed provide special insights into the 3-dimensional aspect of normal and abnormal conduction. The 3-dimensional disturbance in conduction, allows electrical waves to cross from inside to outside and vice versa. This is an important mechanism for the development of atrial fibrillation and other cardiac arrhythmias. This 3-dimensional disturbance in conduction is also seen more in extra atrial beats than in the normal heart rhythm. This is one explanation why an extra atrial beat can lead to the development of atrial fibrillation. In conclusion, this thesis shows how important the nervous system is in the development of cardiac arrhythmias and how we can respond to this by neurostimulation techniques. Detailed mapping of 3-dimensioanle atrial conduction is essential to better understand cardiac arrhythmias and thus improve treatment.