Expert Cardiac Electrophysiology Care in Houston

Supraventricular tachycardia (SVT) refers to a group of abnormally fast heart rhythms that originate in the upper chambers of the heart or the AV node. During an episode, the heart rate can accelerate to 150–250 beats per minute.

Types of SVT

• AV Nodal Reentrant Tachycardia (AVNRT) — the most common type
• AV Reentrant Tachycardia (AVRT) — involves an accessory pathway
• Atrial Tachycardia — originates from a focus in the atria

Treatment Options

• Vagal maneuvers to interrupt episodes
• Medications to control or prevent episodes
• Catheter ablation — a highly effective, often curative procedure

Pulsed field ablation (PFA) represents a major advancement in catheter-based treatment for atrial fibrillation. Unlike radiofrequency ablation (which uses heat) or cryoablation (which uses extreme cold), PFA uses ultra-rapid, high-voltage electrical pulses to selectively target heart tissue while preserving surrounding structures such as the esophagus, phrenic nerve, and pulmonary veins.

How PFA Works

PFA delivers precisely timed electrical fields that create microscopic pores in the membranes of targeted cardiac cells — a process called irreversible electroporation. This disrupts the abnormal electrical signals causing atrial fibrillation while leaving neighboring tissues largely unaffected, significantly reducing the risk of collateral damage that can occur with thermal-based ablation.

Advantages of PFA

• Tissue selectivity — targets heart muscle while sparing the esophagus, nerves, and blood vessels
• Reduced complication risk — lower rates of esophageal injury, phrenic nerve damage, and pulmonary vein stenosis
• Shorter procedure times — many PFA procedures are completed faster than traditional ablation
• Conscious sedation option — some PFA systems can be performed without general anesthesia
• Durable lesions — clinical trials demonstrate strong long-term success rates for both paroxysmal and persistent atrial fibrillation

Who Is a Candidate?

PFA is FDA-approved for the treatment of both paroxysmal and persistent atrial fibrillation. It may be an especially good option for patients who prefer to avoid general anesthesia, those concerned about the risks of thermal ablation, or patients undergoing their first ablation procedure. Dr. Colombowala can help determine whether PFA is the right approach for your specific situation.

For decades, atrial fibrillation was often managed with a "wait and see" approach — controlling heart rate with medication and adding rhythm-control treatments only if symptoms worsened. Landmark research has fundamentally changed this paradigm, demonstrating that early, proactive intervention leads to significantly better long-term outcomes.

What the Evidence Shows

The EAST-AFNET 4 trial, a major international study published in the New England Journal of Medicine, found that patients who received early rhythm-control therapy within the first year of their AFib diagnosis had a 21% lower risk of cardiovascular death, stroke, and hospitalization for heart failure compared to patients managed with usual care. The trial was stopped early because the benefit of early treatment was so clear.

Why Early Treatment Matters

• AFib is a progressive condition — the longer it persists, the more the heart remodels and the harder it becomes to restore normal rhythm
• Early intervention helps prevent the structural changes (atrial fibrosis and dilation) that make AFib more difficult to treat over time
• Patients treated early have lower rates of stroke, even when on appropriate blood thinners
• Maintaining normal rhythm early reduces the risk of developing heart failure
• Catheter ablation, especially with advanced techniques like pulsed field ablation, is most effective when performed earlier in the disease course

What This Means for You

If you have been recently diagnosed with atrial fibrillation — or suspect you may have it — seeking evaluation with an electrophysiologist sooner rather than later can make a meaningful difference in your long-term cardiovascular health. Dr. Colombowala works with each patient to develop a personalized treatment strategy that may include lifestyle modifications, medication management, or catheter ablation to restore and maintain normal heart rhythm early in the disease process.

A pacemaker is a small device implanted under the skin, typically near the collarbone, that sends electrical impulses to the heart to maintain an adequate heart rate. Modern pacemakers are sophisticated, long-lasting, and can be monitored remotely.

When Is a Pacemaker Needed?

• Symptomatic bradycardia (slow heart rate)
• Heart block — disrupted electrical signals between chambers
• Sick sinus syndrome
• After certain ablation procedures

Types of Pacemakers

• Single-chamber — one lead in the right ventricle or atrium
• Dual-chamber — leads in both the right atrium and ventricle
• Leadless pacemakers — miniature devices placed directly in the heart
• His-bundle and left bundle branch pacing — advanced physiologic pacing

An implantable cardioverter-defibrillator (ICD) is a device similar to a pacemaker that continuously monitors heart rhythm. If it detects a dangerously fast or chaotic rhythm, it delivers a precisely calibrated electrical shock to restore the normal heartbeat.

Who May Benefit?

• Survivors of cardiac arrest
• Patients with significantly reduced heart function (low ejection fraction)
• Certain inherited heart rhythm conditions
• Patients with sustained ventricular tachycardia

Types of ICDs

• Transvenous ICD — traditional device with leads placed through the veins into the heart
• Subcutaneous ICD (S-ICD) — the lead sits just under the skin along the breastbone, with no wires inside the heart or veins, reducing the risk of lead-related complications
• Extravascular ICD (EV-ICD) — a newer system that places the lead under the breastbone (substernal) rather than inside the heart, combining the benefits of no intracardiac leads with the ability to deliver anti-tachycardia pacing
• CRT-D — combines defibrillator with cardiac resynchronization therapy for patients with heart failure

Cardiac monitoring involves wearing or having implanted a small device that records the heart's electrical activity over time. Because many arrhythmias occur intermittently, extended monitoring dramatically increases the likelihood of capturing and diagnosing the cause of symptoms.

Types of Monitors

• Holter monitor — continuous recording for 24–48 hours
• Event monitor — patient-activated recording over 2–4 weeks
• Mobile cardiac telemetry (MCT) — real-time continuous monitoring for up to 30 days
• Implantable loop recorder (ILR) — a tiny device implanted under the skin that monitors for up to 3 years

When Is Monitoring Recommended?

• Unexplained palpitations, dizziness, or fainting
• Suspected atrial fibrillation
• Monitoring after ablation procedures
• Evaluating unexplained stroke (cryptogenic stroke)

Syncope — the medical term for fainting — is a temporary loss of consciousness caused by a brief drop in blood flow to the brain. While some episodes are harmless, others can signal a serious underlying cardiac or neurological condition. An electrophysiologist plays a critical role in distinguishing benign causes from potentially life-threatening arrhythmias.

Common Causes of Syncope

• Cardiac arrhythmias — dangerously fast or slow heart rhythms that reduce blood flow to the brain
• Vasovagal syncope (neurocardiogenic) — the most common type, triggered by prolonged standing, heat, emotional stress, or pain
• Orthostatic hypotension — a significant drop in blood pressure upon standing
• Structural heart disease — conditions such as aortic stenosis, hypertrophic cardiomyopathy, or severely reduced heart function

What Is Dysautonomia?

Dysautonomia refers to a group of conditions in which the autonomic nervous system — which controls involuntary functions like heart rate, blood pressure, and digestion — does not work properly. This can lead to lightheadedness, fainting, rapid heart rate on standing, exercise intolerance, fatigue, and difficulty concentrating. Common forms include postural orthostatic tachycardia syndrome (POTS), neurocardiogenic syncope, and autonomic neuropathy.

Diagnostic Evaluation

• Tilt table testing — reproduces symptoms in a controlled setting to diagnose vasovagal syncope and POTS
• Cardiac monitoring — Holter monitors, event recorders, or implantable loop recorders to capture rhythm disturbances
• Electrophysiology study — to evaluate for arrhythmias as a cause of syncope
• Autonomic function testing — to assess heart rate and blood pressure responses

Treatment Options

Treatment depends on the underlying cause and may include lifestyle modifications (increased fluid and salt intake, compression garments, counter-pressure maneuvers), medications to stabilize heart rate or blood pressure, cardiac devices such as pacemakers for certain types of syncope, or catheter ablation if an arrhythmia is identified as the cause. Dr. Colombowala provides a comprehensive evaluation to determine the cause of fainting episodes and develop a tailored management plan.