What is Electrophysiology?
Cardiac Electrophysiology, is the study of the electrical activities of the heart, specifically for the purposes of diagnosing and treating heart rhythm disorders.
Dr. Marwan Bahu specializes in the diagnosis and treatment of heart rhythm disorders for patients at Biltmore Cardiology, and has more than 20 years of experience diagnoising and treating heart rhythm disorders.
Diagnosing Heart Rhythm Disorders
The process of making an accurate diagnosis starts with an office evaluation. Taking the time with our patients early on is definitely worthwhile, an investment that minimizes expensive, unnecessary testing and charts the shortest path toward diagnosis and treatment of the problem. There are various types of heart rhythm disorders. Some are associated with symptoms. Others are asymptomatic. Some are life-threatening, most are not. There are times when only reassurance is all that is needed. Other times, diagnosis leads to a curative procedure. Medications remain an important part of treatment. Devices like pacemakers and defibrillators are often used as well.
The initial diagnosis starts with assessing the overall health of the heart. An echo cardiogram to assess muscle strength and valve function is often needed. A stress test to assess coronary risk may also be attained early on in the evaluation. Dr. Bahu often orders an EKG monitor to record a patient’s heart rhythm at the time that the patient is symptomatic. Some patients’ symptoms are infrequent, thus, necessitating long-term monitoring. The device, implanted under the skin, may be needed if long-term monitoring is desired. An electrophysiology study (EP study) is an outpatient procedure that may be needed to establish diagnosis in a more efficient manner. This is especially important if a dangerous rhythm disorder is suspected. An EP Study is a low-risk procedure. The rhythm problem could be eliminated by ablation during the procedure, as well.
An EP study is a low-risk outpatient procedure. Once the patient is made comfortable, 3 catheters (insulated wires) are placed into the femoral vein at the right groin, and are advanced into the heart chambers and placed at strategic locations. Electrical signals are then transmitted from the heart and fed into a computer (mapping system) for analysis. The heart is stimulated by the catheters in order to elicit the abnormal rhythm. Once the rhythm is brought on it can be pinpointed and eliminated.
Elimination of rhythm disorders is performed during EP study with a process called ablation. During ablation, energy is applied to the source of the abnormal rhythm to extinguish it. Traditionally, the energy source used is radio frequency energy, which heats up the tissue and destroys it. Freezing energy can also be used. This type of ablation is called cryoablation. It can be done with a freezing catheter or a balloon. The latter is used typically to ablate the circumference of the pulmonary veins that attach to the back of the heart, a common source of abnormal rhythms. Other ablation sources are being investigated, such as laser, high frequency ultrasound and microwave energy.
All of these modalities have their pluses and minuses. Radiofrequency energy is still the most commonly used modality because of its flexibility and speed of application. Dr. Bahu may employ more than 1 modality in any given procedure, if necessary. He believes the perfect energy source that suits every patient has not yet been invented. The search goes on.
Rhythm disorders vary in location and level of complexity. They are typically divided into upper versus lower chamber rhythms (supraventricular versus ventricular tachycardia). Some come from a single site; others are caused by multiple active sites. Rhythm disorders that come from multiple sites are more difficult to eradicate. Multiple sites generating abnonnal electricity in the upper chamber of the heart create a common rhythm disorder called atrial fibrillation (AF). AF has been the focus of Dr. Bahu’s attention for the last 15 years because it is the most common rhythm problem and it is the most challenging one.
In some patients, AF is associated with a stroke that can be debilitating. Although today we are better than ever at diagnosing and treating atrial fibrillation, there is definitely room for improvement. Up until 15 years ago, medication and pacemaker implantation were the only 2 options available for treatment of atrial fibrillation. Ablation of atrial fibrillation was only a dream back then. Now the dream of eliminating atrial fibrillation for most people is a reality. Dr. Bahu has performed several thousand atrial fibrillation ablations since 1997. His success rate in eliminating atrial fibrillation is, on the average, 85%. Back in 1997 our success rate was only 50%. In a select group of patients his success rate now is higher than 90%. Two sessions may be required to achieve success in some patients.
Traditionally stroke prevention was achieved by taking a blood thinner (anticoagulant) called warfarin (or Coumadin). This medication is difficult to regulate and its level in the blood is often affected by food and other medications. New anticoagulants like Pradaxa and Xarelto have come onto the market recently and they have the advantage of being easy to dose and their level in the blood is not affected by food or medication. The process of anticoagulation (blood thinning) has the unfortunate risk of bleeding. Patients with the highest risk of stroke have also the highest risk of bleeding. In the past few years a number of devices have been developed to reduce risk of stroke without thinning the blood. This is achieved by isolating a part of the heart called the left atrial appendage that often harbors clots. The left atrial appendage (LAA) is a pouch that sticks out of the left upper chamber of the heart (left atrium). During atrial fibrillation the slow flow in the left atrium leads to clot formation.
Ninety percent of the time the clots are formed in the left atrial appendage. The clot can then dislodge and travel to the brain and cause a stroke. The left atrial appendage can be sealed from the bloodstream from the inside of the heart with a device called the Watchman device, or the left atrial appendage can be captured from outside of the heart and tied off with a device called the Lariat device. For patients over the age of 80, those at risk for falls and those with a history of bleeding, these devices are options that ought to be seriously considered. Some physicians believe that patients who require anticoagulants in addition to being on Plavix and aspirin are at an increased risk for bleeding and, therefore, may benefit from these devices as well.