The key difference between Cardiac Resynchronization Therapy (CRT) and an Implantable Cardioverter-Defibrillator (ICD) is their primary function: CRT aims to improve the coordination of the heart's contractions, while an ICD is designed to correct life-threatening heart rhythm abnormalities.
CRT vs. ICD: A Detailed Comparison
| Feature | Cardiac Resynchronization Therapy (CRT) | Implantable Cardioverter-Defibrillator (ICD) |
|---|---|---|
| Primary Goal | Improve heart failure symptoms by synchronizing ventricular contractions. | Prevent sudden cardiac death by correcting dangerous heart rhythms. |
| Mechanism | Biventricular pacing: Stimulates both ventricles to contract in unison. | Delivers electrical shocks or pacing to terminate ventricular tachycardia or fibrillation. |
| Target Condition | Heart failure with left ventricular dyssynchrony. | Ventricular tachycardia or ventricular fibrillation. |
| Device Type | Special type of pacemaker with leads in both ventricles. | Device that can deliver shocks and/or pacing. |
| Benefit | Improved cardiac output, reduced heart failure symptoms. | Prevention of sudden cardiac death. |
In simpler terms:
-
CRT is like a conductor ensuring all parts of an orchestra (the heart) play together harmoniously. It's used when the ventricles aren't contracting in a coordinated way, which weakens the heart's pumping ability in heart failure.
-
ICD is like a safety net that catches the heart when it starts to beat dangerously fast or erratically. It delivers an electrical shock to restore a normal rhythm and prevent sudden cardiac arrest.
Many patients with heart failure and ventricular arrhythmias can benefit from a combination device: a CRT-D, which combines the functions of both CRT and an ICD. This provides both improved coordination and protection against life-threatening arrhythmias.
