Generally the most common situation is to address bradycardia because of decreased sinus node function - sick sinus node syndrome, or the presence of atrioventricular block.
Generally this is considered a single-chamber or dual-chamber pacemaker, depending on the situation. If it is just the sinus node, and the AV conduction function is OK, we can place a pacing electrode in the right atrium alone, which creates a single-chamber pacemaker in the AAI mode, which is more physiologic, and the price is lower; and if there is a problem with the AV conduction function, then it is generally a dual-chamber pacemaker, which is placed in the right atrium and the right ventricle. One pacing electrode is placed in each right atrium right ventricle, sequential pacing, DDD mode.
But there are also other cases, for example, if you are treating heart failure, then you can use a three-chamber pacemaker, with one pacing electrode in the right atrium and one in the right and left ventricles, so that you can have atrial coordination and synchronization of the left and right ventricles, or even a four-chamber, with one electrode in each of the left and right atria and each of the left and right ventricles. This is called resynchronization therapy. But frankly, because heart failure is the end result, your atrioventricular incoordination, left and right ventricular desynchronization, that's the result, not the cause, so it's only effective for some people. And it's expensive.
Additionally there are, because of hypertrophic cardiomyopathy, the use of dual-chamber pacemakers, control of atrioventricular conduction time, so that septal diastole is more reasonable, to reduce the narrowing of the left ventricular outflow pathway, and that also makes a difference.
In short, different cases, pacemakers are different treatments, the most critical point, you understand because of what implanted pacemakers, such as your coronary artery disease, at the same time lead to atrioventricular block, the pacemaker at least to solve the problem of your slow heart rate, for the coronary artery disease itself is not a direct therapeutic effect, the coronary artery disease, how you should be treated how to be treated, not to say that I'm good for several tens of thousands of dollars a