Cardiac ablation is a medical technology used to treat some abnormal heart rhythms, called arrhythmias. It works by finding small areas of heart tissue that send faulty electrical signals and then disabling those areas. This matters because arrhythmias can make the heart beat too fast, too slowly, or irregularly, which can reduce blood flow and cause symptoms such as palpitations, dizziness, or fatigue.
A thin flexible catheter allows doctors to treat the problem from inside the heart without open-heart surgery.
During the procedure, the catheter is guided through a blood vessel and into the heart using imaging and electrical mapping. The catheter tip delivers either radiofrequency energy to heat tissue or cryo energy to freeze tissue, creating a small scar that blocks abnormal signals. The goal is to interrupt the electrical pathway that triggers or maintains the arrhythmia while preserving normal conduction.
Physics ideas such as energy transfer, temperature change, and electrical signal propagation help explain how the device works.
Key Facts
- Cardiac ablation treats arrhythmias by destroying or isolating tiny regions of abnormal electrical tissue.
- Radiofrequency ablation uses alternating electrical current to heat tissue, often to about 50 to 60 °C.
- Cryoablation removes heat from tissue and can cool the target region to about -40 to -80 °C.
- Electrical power delivered by a catheter can be described by P = IV, where P is power, I is current, and V is voltage.
- Thermal energy transfer can be estimated with Q = mcΔT, where Q is heat, m is mass, c is specific heat, and ΔT is temperature change.
- A successful lesion blocks unwanted conduction while allowing normal heart signals to travel through healthy pathways.
Vocabulary
- Arrhythmia
- An arrhythmia is an abnormal heart rhythm caused by problems in the heart's electrical signaling system.
- Catheter
- A catheter is a thin flexible tube that can be guided through blood vessels to reach the heart.
- Radiofrequency ablation
- Radiofrequency ablation is a treatment that uses high-frequency electrical energy to heat and damage targeted heart tissue.
- Cryoablation
- Cryoablation is a treatment that freezes targeted tissue to stop it from conducting abnormal electrical signals.
- Lesion
- A lesion is the small controlled area of damaged tissue created during ablation to block unwanted electrical conduction.
Common Mistakes to Avoid
- Thinking ablation burns or freezes the whole heart, which is wrong because the catheter targets very small regions of abnormal tissue.
- Assuming all arrhythmias are treated the same way, which is wrong because the target location and energy choice depend on the specific rhythm problem.
- Confusing radiofrequency energy with a shock from a defibrillator, which is wrong because ablation applies controlled local energy rather than a brief whole-heart electrical reset.
- Forgetting that tissue damage is the goal at the target site, which is wrong because the controlled scar is what blocks the bad signal pathway.
Practice Questions
- 1 A catheter delivers 25 W of radiofrequency power for 40 s. How much energy is delivered to the tissue in joules?
- 2 A small tissue region has a mass of 2.0 g and an approximate specific heat of 3500 J/kg°C. How much heat must be added to raise its temperature by 30 °C?
- 3 Explain why creating a small scar in the correct location can stop an arrhythmia without stopping the entire heartbeat.