Implanted cardioverter defibrillators (ICDs) continuously monitor the heart rate. When the rate is more than a programmable value, the ICD will assume the patient has a malignant ventricular arrhythmia and provide a shock through a lead placed in the right ventricle.
Implanted pacemakers are used for different purposes and for different underlying conditions.
A pacemaker delivers a current to the myocardial tissue, initiating a propagation wave of depolarization. This can be accomplished with single- or dual-chamber pacing systems, which are chosen according to the underlying condition.
As a rule, pacemakers are used to treat bradycardia and certain types of ventricular arrhythmias.
Underlying conditions include sinus node dysfunction, atrioventricular (AV) conduction abnormalities, cardiomyopathy, autonomic nervous system disorders, and atrial fibrillation.
ICDs are used for patients with nonsustained ventricular tachycardia and reduced left ventricular function due to coronary artery disease.
Medications will indicate if the patient is treated for an underlying arrhythmia, to prevent the development of ischemic cardiac events (primary prevention), or to prevent additional ischemic events from occurring (secondary prevention).
- Oral Health Care Considerations