Cardiac resynchronization therapy (CRT) is an advanced treatment method that ensures synchronized heart function in heart failure patients. Also known as a three-chamber pacemaker, CRT improves pumping function by stimulating both ventricles of the heart simultaneously.
What is CRT?#
CRT is a special pacemaker that stimulates the left and right ventricles of the heart in a synchronized manner. Unlike regular pacemakers, it contains three electrodes:
- Right atrium electrode: Stimulates the upper chamber of the heart
- Right ventricle electrode: Stimulates the right lower chamber
- Left ventricle electrode: Stimulates the left ventricle via the coronary sinus
How Does CRT Work?#
Left bundle branch block is frequently seen in heart failure. In this condition:
- Left ventricle contracts with delay
- Heart works inefficiently
- Pumping power decreases
CRT, by stimulating both ventricles simultaneously:
- Provides synchronized contraction
- Increases pumping efficiency
- Reduces heart failure symptoms
Who is CRT Suitable For?#
Indications#
Definite Indications:
- Sinus rhythm + left bundle branch block (QRS ≥150 ms)
- Ejection fraction ≤35%
- NYHA class II-IV symptoms
- Symptomatic despite optimal medical therapy
Possible Indications:
- Wide QRS without left bundle branch block (≥150 ms)
- Atrial fibrillation + low EF
- Patients requiring high rate of ventricular pacing
Types of CRT#
CRT-P (Pacemaker):
- Pacing function only
- In patients with low sudden death risk
CRT-D (Defibrillator):
- Pacing + defibrillation
- In patients with high sudden death risk
- Most commonly preferred type
How is CRT Implantation Performed?#
Pre-Procedure Preparation#
- Echocardiography
- ECG (QRS width measurement)
- Coronary sinus anatomy evaluation
- Blood tests
- Anticoagulant adjustment
Procedure Steps#
- Anesthesia: Local anesthesia + sedation
- Vascular access: Subclavian vein
- Right atrium electrode: Placement in right atrial appendage
- Right ventricle electrode: Placement in right ventricular apex
- Left ventricle electrode: Placement via coronary sinus (most critical step)
- Testing: Verification of electrode function
- Generator connection: Connecting electrodes to device
- Closure: Skin closed with sutures
Procedure Duration#
CRT implantation usually takes 2-3 hours (depending on left ventricle electrode placement difficulty).
CRT Results#
Expected improvements after successful CRT:
Short Term:
- Reduction in shortness of breath
- Increase in exercise capacity
- Improvement in quality of life
Long Term:
- Increase in ejection fraction
- Reduction in heart size (reverse remodeling)
- Decrease in hospitalization rate
- Survival advantage
Response Rates:
- Approximately 70% of patients respond to CRT
- 30% may be “super responders” (EF normalizes)
CRT Risks#
Procedure risks:
- Coronary sinus dissection
- Left ventricle electrode placement failure (5-10%)
- Phrenic nerve stimulation (diaphragm contraction)
- Infection
- Pneumothorax
- Electrode dislocation
CRT Optimization#
Optimization may be needed for CRT to provide maximum benefit:
- AV delay adjustment
- VV delay adjustment
- Echocardiography-guided programming
Frequently Asked Questions#
Does CRT cure heart failure?
Is CRT implantation painful?
How long does a CRT battery last?
What if I don't respond to CRT?
Can I lead a normal life with CRT?
Appointment and Contact#
If you would like to schedule an appointment for CRT evaluation or implantation:
📍 Avrasya Hospital - Beştelsiz Mah. 101. Sokak No:107, Zeytinburnu, Istanbul
📞 Phone: +90 212 665 50 50 (Ext: 4012)
This content has been prepared by Assoc. Prof. Dr. Habib Çil for general informational purposes. Please consult a cardiology specialist for definitive diagnosis and treatment.
Related Arrhythmia Treatments#
Other arrhythmia treatments related to CRT pacemaker:
- Biventricular Pacemaker - CRT pacemaker
- Heart Failure - Heart failure treatment
- ICD - Implantable cardioverter defibrillator
- Echocardiography - Heart ultrasound
- Permanent Pacemaker - Bradycardia treatment