North Mississippi Medical Center's cardiac electrophysiologists deal with the heart’s electrical system - the diagnosis and treatment of heart rhythm disorders.
A pacemaker is a two-part electrical system that includes a pulse generator (pacemaker) and one or two leads, or wires, which deliver impulses to the heart. The leads also carry signals back from the heart. By “reading” these signals, the pulse generator is able to check the heart’s activity and respond appropriately. A pacemaker helps to pace the heart when its own rate is too slow to pump enough blood to the body.
An implantable cardioverter defibrillator (ICD) administers an electric shock to control irregular heartbeat and restore it to normal. The cardiologist places leads (wires) in the heart's right ventricle (single chamber system) or in the right ventricle and atrium (dual chamber system). Both single chamber or dual chamber systems may require many leads.
A biventricular device (pacemaker or ICD) treats moderate to severe heart failure. This feature is available on some pacemakers. Unlike standard devices, the biventricular system has leads (wires) to the right ventricle with an additional lead to the left ventricle. By pacing the left ventricle from two sites, the heart’s contraction is "resynchronized,” which can enhance the heart's pumping efficiency.
NMMC electrophysiologists perform extraction (removal) of device and/or lead(s) as well as device replacement and/or lead replacement or revision surgery. They coordinate extraction surgery with a cardiothoracic surgeon and anesthesia services.
An implantable loop recorder (ILR) is inserted under the skin in the chest to record arrhythmias. An injectable ILR can be inserted at your bedside without sedation. The benefits of an injectable ILR versus a regular implantable ILR are:
- More memory
- Wireless monitoring
- Has remote activator (stores 6.5 minutes of data before remote activation)
- Battery lasts three years versus 18-24 months
- Patient can have an MRI
Electrophysiology testing can identify specific areas in the heart that may be responsible for abnormally rapid or slow heart rates before radiofrequency catheter ablation or device implantation.
An electrophysiologist may do radiofrequency catheter ablation or cryoablation to destroy the AV node or specific areas of heart tissue responsible for an irregular heart rhythm. If the AV node is destroyed to prevent fast heart rates, you will need a pacemaker to send regular impulses to the lower heart chambers (ventricles). If tissue other than the AV node is responsible for rapid heart rates, you may not need a pacemaker.
Cardiac ablation can treat heart rhythm disorders (arrythmias), including atrial fibrillation, atrial flutter, supraventricular tachycardia, Wolff-Parkinson-White (WPW) syndrome and ventricular tachycardia.
Left atrial appendage closure uses a permanent implant to close the heart's left atrial appendage to reduce your risk of stroke.
Cardioversion uses an electrical signal to “shock” an arrhythmia. It can be done externally or internally if the patient has an implantable cardioverter defibrillator (ICD).
Insurance regulations require a 90-day waiting period after bypass surgery if you are being considered for an implantable cardiac defibrillator. In the interim, physicians may recommend you wear a LifeVest® defibrillator while they assess long-term risk for arrhythmia, or irregular heart rhythm.
The LifeVest, which is custom fit for you and worn under clothes, constantly monitors your heart, detects arrhythmias and, if needed, shocks your heart back into normal rhythm. The external defibrillator can protect you until an internal defibrillator can be implanted or your heart recovers.
Radiofrequency Septal Ablation
NMMC cardiac electrophysiologist Karl Crossen, M.D., developed a procedure known as radiofrequency septal ablation to treat hypertrophic obstructive cardiomyopathy (HCM), a genetic disease where the heart’s septum is enlarged or thickened. This condition can cause shortness of breath, chest pain, fainting, congestive heart failure and abnormal heart rhythms which are sometimes fatal. Before, the only treatments had been surgery to remove part of the septum or injecting alcohol into a blood vessel, which causes an area of the septum to die.
In radiofrequency septal ablation, he uses an advanced cardiac mapping system to target the thickest part of the septum. Then he uses a catheter to deliver radiofrequency energy to ablate (or burn) the excess tissue and reduce the thickness.
Micra® Transcatheter Pacing System (TPS)
NMMC now offers the world’s smallest pacemaker for patients with problematic slow heart rates. The Micra® Transcatheter Pacing System (TPS) is an implantable cardiac device that provides the most advanced pacing technology at one-10th the size of a traditional pacemaker. While traditional pacemakers involve surgical implantation of a device in the chest with flexible wires called “leads” extending into the heart, Micra is 93 percent smaller than traditional pacemakers (measuring about the size of a large vitamin), which makes it cosmetically invisible. More importantly, Micra requires neither the leads going into the heart nor the surgical “pocket” under the chest. Instead, Micra is small enough to be delivered through a catheter and implanted directly into the heart in a procedure similar to a heart catheterization.
NMMC was among the first hospitals nationwide to implant the new Evia HF-T triple-chamber cardiac resynchronization therapy pacemaker. The device puts out pulses to keep the heart beating regularly and on time, improving the health of patients with bradycardia and heart failure. Its wireless home monitoring technology uses a cellular network to pick up information from the patient’s implanted device and transmit it to cardiologists daily. The device also measures thoracic impedance or lung fluid levels and alerts the physician before full-fledged heart failure develops.