These are problems in the electrical function of the heart that cause abnormal heart rhythms (arrhythmias). Sometimes the heart beats irregularly, too slowly (bradycardia), too fast (tachycardia), or it can simply stop (sudden cardiac death syndrome). A heart specialist called an electrophysiologist treats arrhythmias. MMC’s electrophysiology (EP) team has expertise in treating the full range of arrhythmias.


Among the types of arrhythmias are:

  • Atrial fibrillation-Read about New Treatment for Chronic A-Fib
  • Atrial flutter
  • Paroxysmal atrial tachycardia (PAT)
  • Premature supraventricular or atrial contractions (PACs)
  • Premature ventricular complexes (PVCs)
  • Sick sinus syndrome
  • Sinus arrhythmia
  • Sinus tachycardia
  • Sudden cardiac death syndromes
  • Supraventricular tachycardia (SVT)
  • Ventricular fibrillation
  • Ventricular tachycardia
  • Wolff-Parkinson-White syndrome


Arrhythmias are most often treated with lifestyle changes, medications, special devices or minimally invasive procedures to regulate the rhythm of the heart. MMC offers a full array of the most advanced EP treatment resources, provided by one of the most experienced EP teams in New England:

Pacemaker implantation – A pacemaker is a small device, surgically implanted under the skin, which sends electrical impulses to the heart muscle to maintain an appropriate heart rate and rhythm.

Cardiac resynchronization therapy (CRT) or biventricular pacing – This is a special pacemaker used to treat the delay in heart contractions that can occur in advanced heart failure. In about 30% of patients with heart failure, an abnormality in the heart's electrical conduction system (called an intraventricular conduction delay or bundle branch block) causes the heart’s two ventricles to beat out of synch, reducing the efficiency of an already-damaged heart. CRT re-coordinates the beating of the two ventricles so they beat simultaneously.

Implantable cardioverter defibrillator (ICD) placement – Also surgically implanted under the skin, an ICD is an electronic device that constantly monitors the heart’s rhythm. When it detects an abnormal heart rhythm, it delivers energy to shock the heart back into beating regularly.

Catheter ablation – The most effective treatment for some arrhythmias is to destroy the tissue in the heart where the short circuit that’s causing the rhythm disturbance starts. This non-surgical procedure is called ablation, and it involves threading a catheter through a blood vessel to locate the problem using fluoroscopy (a type of x-ray). Through the catheter, the EP specialist then delivers either radiofrequency energy to cauterize (burn), or intense cold (cryotherapy) to freeze and destroy a small amount of tissue, which helps restore a healthy heart rhythm. Catheter ablation is successful in a high percentage of cases, eliminating the need for open-heart surgeries or long-term drug therapies in many patients.

AV Node Ablation – The AV node is the electrical pathway that connects the atria (upper chambers of the heart) to the ventricles (lower chambers). By disrupting this pathway with a catheter ablation procedure, it prevents the upper chambers from controlling the rate of the lower chambers (which determines the heart rate and pulse rate), and can reduce the symptoms of atrial fibrillation. Patients who receive AV node ablation will require a permanent pacemaker to activate the ventricles.

Cardioversion – When the heart beats too quickly, blood can no longer circulate effectively in the body. Cardioversion restores the heart's normal rhythm and efficient pumping action by applying a controlled electric shock to the exterior of the chest.

Medical management – For certain patients, antiarrhythmic and other cardiac medications such as beta blockers are used to control abnormal heart rhythms. Some patients may also have to take anticoagulant medications such as warfarin (Coumadin®) to reduce the risk of blood clots. MMC’s EP specialists provide close, ongoing medical management for these patients.

Device management – Patients with implanted devices must be regularly monitored. MMC’s EP specialists currently follow an estimated 6,000 patients with pacemakers and 3,000 with ICDs, reflecting the long-term relationships our physicians have with patients.

Laser lead extraction – A lead is a special wire that delivers energy from a pacemaker or ICD to the heart muscle. Extraction is needed when the leads are not working properly due to damage, the build-up of scar tissue or infection. This is a technically challenging procedure requiring considerable expertise, and MMC is the only hospital in Maine to offer it.

Open heart surgery – There also are surgical approaches to treating atrial fibrillation and/or atrial flutter in appropriately selected patients. The traditional Maze procedure, in which a number of incisions are made in the heart’s atria (upper chambers), produces scar tissue that acts as insulation and forces the heart’s electrical impulses to travel in a more normal direction. The operation requires opening the chest and stopping the heart temporarily with use of the heart-lung machine.

Convergent Procedure – Performed by both a cardiothoracic surgeon and a cardiologist who is trained in electrophysiology working together, this approach is less invasive than open heart surgery and can be highly effective in restoring normal heart rhythm in appropriate patients. Learn About a New Treatment for Patients with Chronic A-fib

Program Highlights

Electrophysiology (EP) is the cardiac subspecialty dedicated to treating arrhythmias. For people who have or are at risk of having arrhythmias, MMC Cardiovascular Institute offers extensive and highly advanced EP resources for diagnosis and treatment, and more EP experience than any other hospital in Maine.

Today our EP specialists perform more than 1,900 procedures a year, placing MMC among the top centers in all of New England in terms of volume. As a result of this experience, we have developed expertise in managing more complex arrhythmias, particularly the treatment of atrial fibrillation and ventricular tachycardia, with excellent patient outcomes.

Notably, MMC is the only hospital in Maine with a pediatric EP specialist who treats children with arrhythmias.

In addition, MMC has been involved in multi-center clinical trials since the 1980s, participating in major studies to develop anti-arrhythmic drugs and devicesgiving our patients access to new treatments before they are available anyplace else in Maine and, sometimes, New England.

To make our EP capabilities more accessible and convenient, our EP specialists are available for consultation at hospitals or practice offices of Maine Medical Partners  MaineHealth Cardiology in Augusta, Waterville, Damariscotta, Lewiston, Rockport, Portland and Scarborough.