What is Cardiac Resynchronization Therapy (CRT), and how does it help in treating heart failure?

 

Cardiac Resynchronization Therapy (CRT)

Cardiac Resynchronization Therapy (CRT) is a specialized treatment for heart failure (HF) that helps improve the heart's efficiency and coordination of contractions. It involves the use of a pacemaker-like device to restore the normal timing of the heart’s electrical signals, ensuring the ventricles (lower chambers of the heart) pump blood more effectively.

Heart failure occurs when the heart cannot pump blood efficiently, leading to fatigue, breathlessness, swelling (edema), and other complications. CRT is particularly beneficial for patients with moderate to severe heart failure and an abnormal electrical conduction system, such as a left bundle branch block (LBBB).\

For information on the cost of CRT-D (Cardiac Resynchronization Therapy with Defibrillator) in India, visit: CRT-D Cost in India.

Understanding Heart Failure and Electrical Dysfunction

What is Heart Failure?

Heart failure (HF) is a chronic condition where the heart muscle is too weak or stiff to pump blood efficiently. It is classified into:

  • Heart Failure with Reduced Ejection Fraction (HFrEF) – The heart’s pumping ability is weak.

  • Heart Failure with Preserved Ejection Fraction (HFpEF) – The heart muscle is stiff and does not fill properly.

Patients with HFrEF and electrical conduction problems are ideal candidates for CRT.

How Electrical Abnormalities Affect Heart Function?

The heart pumps blood due to electrical signals that coordinate contractions of the right and left ventricles. In some heart failure patients, these signals become delayed or uncoordinated, causing the ventricles to pump out of sync. This leads to:
✅ Weaker heart contractions
✅ Reduced oxygen-rich blood supply
✅ Worsening heart failure symptoms

A left bundle branch block (LBBB) is the most common electrical abnormality affecting heart failure patients, leading to asynchronous contractions of the ventricles.

What is Cardiac Resynchronization Therapy (CRT)?

CRT is a device-based therapy that restores synchronized ventricular contractions using a specialized pacemaker known as a CRT device. This device has three leads that send electrical impulses to:
✅ Right atrium (upper chamber)
✅ Right ventricle
✅ Left ventricle

By sending synchronized electrical impulses, the CRT device optimizes the heart’s pumping function, improving blood circulation and oxygen delivery.

How Does CRT Help in Treating Heart Failure?

1. Restores Synchronized Ventricular Contractions

  • In heart failure patients with conduction delays, the left and right ventricles do not beat together, leading to inefficient blood pumping.

  • CRT corrects this delay by coordinating the contractions of both ventricles.

2. Improves Ejection Fraction (EF)

  • Ejection fraction (EF) is the percentage of blood pumped out of the left ventricle per heartbeat.

  • Normal EF is 55-70%, while heart failure patients may have EF below 40%.

  • CRT helps increase EF, improving overall heart function.

3. Enhances Oxygen Delivery to Organs

  • With improved blood circulation, organs receive more oxygen and nutrients, reducing symptoms like fatigue and shortness of breath.

4. Reduces Heart Failure Symptoms

  • CRT significantly reduces symptoms of heart failure, including:
    ✅ Shortness of breath (dyspnea)
    ✅ Swelling in the legs and abdomen (edema)
    ✅ Fatigue and weakness
    ✅ Reduced exercise capacity

5. Lowers the Risk of Hospitalization

  • Studies show that CRT reduces the need for frequent hospital admissions due to heart failure complications.

6. Decreases Mortality Rates

  • CRT increases survival rates by reducing the risk of severe heart failure-related complications.

Types of CRT Devices

There are two main types of CRT devices:

1️⃣ CRT-P (Cardiac Resynchronization Therapy Pacemaker)

  • A pacemaker-only device that helps in synchronizing the heartbeats.

  • Used for patients who do not require defibrillation.

2️⃣ CRT-D (Cardiac Resynchronization Therapy Defibrillator)

  • Combines CRT pacemaker + Implantable Cardioverter Defibrillator (ICD).

  • Used for high-risk patients who might experience life-threatening ventricular arrhythmias.

Who are Ideal Candidates for CRT?

✅ Patients Who Benefit from CRT

CRT is recommended for patients who have:
✔️ Moderate to severe heart failure (NYHA Class II-IV)
✔️ Left Ventricular Ejection Fraction (LVEF) ≤ 35%
✔️ Wide QRS complex (>130 ms) with conduction delays (e.g., LBBB)
✔️ Symptoms despite optimal medical therapy

❌ Patients Who May Not Benefit from CRT

CRT is not effective for patients with:
❌ Mild heart failure (NYHA Class I)
❌ Normal QRS duration (<120 ms) on ECG
❌ Heart failure due to other non-electrical causes

The CRT Implantation Procedure

1️⃣ Pre-Surgery Preparation

  • The patient undergoes ECG, echocardiogram, and blood tests.

  • Local anesthesia is given to numb the area.

2️⃣ Device Implantation

  • Leads are inserted into veins leading to the heart.

  • The CRT device is implanted under the skin near the chest.

3️⃣ Post-Surgery Recovery

  • Most patients go home within 1-2 days.

  • Normal activities can be resumed within a few weeks.

Risks and Complications of CRT

CRT is a safe procedure, but like any medical intervention, it has some risks:

🔴 Infection at the implantation site
🔴 Lead displacement requiring repositioning
🔴 Bleeding or blood clots
🔴 Allergic reaction to anesthesia
🔴 Rare device malfunctions

However, these complications are rare, and the benefits of CRT far outweigh the risks.

Success Rate and Long-Term Benefits of CRT

Clinical studies show that CRT:
✅ Improves symptoms in 60-70% of patients
✅ Reduces mortality by 25-30%
✅ Enhances quality of life significantly
✅ Decreases hospitalization rates by nearly 40%

Patients with CRT report:
✔️ Better exercise tolerance
✔️ Improved heart function
✔️ Longer life expectancy compared to untreated patients

Conclusion

Cardiac Resynchronization Therapy (CRT) is a lifesaving treatment for patients with moderate to severe heart failure and electrical conduction abnormalities. It helps restore synchronized heart contractions, improving blood flow, reducing symptoms, and enhancing quality of life.

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