Arrhythmia Surgery

Pacemakers

The electrical system of the heart is quite complex and very amazing.

A normal pulse is generated by an initial electrical charge that originates in the sino-atrial (SA) node... This structure is located near the junction between a patient's superior vena cava and the right atrium.

The pulse then passes through the right and left atria causing these chambers to contract and then collects at the atrio-ventricular (AV) node... The AV node is located at the very top of the septum separating the left and right ventricular (pumping) chambers.

The AV node then fires electrical pulses through specialized microscopic wiring known as the bundle of His. which then divides into separate electrical branches to the left ventricle and right ventricle simultaneously causing these pumping chambers to contract.

There are a variety of electrical problems that can occur due to aging, heart attacks, and even congenital heart disease.

The two most common indications for permanent pacemakers in adults are sick sinus. syndrome and heart block.. Sick sinus syndrome results from malfunction of the SA node and heart block occurs when there is malfunction of the AV node.

History of Pacemakers

It has been known for a long time that external electrical stimulation of the heart can cause the heart to contract.. Indeed, in 1804, John Aldini in London successfully stimulated hearts to contract on decapitated criminals!

In 1952, Dr. Zoll presented in the New England Journal of Medicine that he was able to pace patients' hearts with external skin electrodes.

One of the most famous heart surgeons who ever lived, Dr. Walter Lillehei in Minneapolis, asked a television engineer named Earl Bakken to help him develop a small portble pacemaker. Mr. Baakken later became the founder of Medtronics Corporation, now a major supplier of pacemakers and other heart related devices.

Cardiac Pacemaker

In 1959, Elmquist and Senning, in Stockhom, placed the first totally implantable pacemaker.. Now, pacemaker insertion is a very common procedure, usually done under local anesthesia, using tiny electrodes inside the heart, attached to a small generator (battery) placed under the skin..

Pacemakers are very effective and very safe.. The batteries usually last 7-10 years and are easy to replace during a second minor operation.

Unfortunately for me, whereas the majority of pacemakers were historically placed by cardiac surgeons in the 1970's, 80's, and most of the 90's, currently nearly all pacemakers are placed by cardiologists.

Cardiologists do a fine job with pacemaker insertions, though I personally wish that the procedure stayed in the surgical arena.. This is a common dilemma in modern medicine.. That is, the overlap of disciplines vying for the same procedures..

Unfortunately, surgeons are "at the bottom of the food chain" and so the referring doctor (cardiologist, internist) would need to send the patient to the surgeon to have a pacemaker done by a surgeon.. That simply isn't going to happen if the cardiologists wants to do the procedure themselves.

ICD Implants

ICD stands for Internal Cardioverter Defibrillator. Modern ICDs look very similar to pacemakers, but they do an additional function.. If the heart goes into a very irregular, life-threatening arrhythmia, the devices sends an electrical charge to the heart and zaps it back into normal rhythm!. It's like carrying around your own personal defibrillation paddles!The technology is so advanced today, largely because of our ability to make smaller and smaller computer chips.

Combined Cardiac Pacemaker, Cardiac Resynchronization, and Defibrillation System

These devices can actually sense your rhythm, record it, analyze it, and then send shock waves to your heart to correct the rhythm problem.. Many of these devices can also serve as a pacemaker as well.

When I was in training, the ICDs were put in by surgeons.. But just like the pacemakers (see discussion above) most ICDs are put in by cardiologists, specifically .cardiology electrophysioloigists (EP)..

EP cardiologists are in great demand.. This is one of the most rapidly expanding fields in medicine.. In addition, studies clearly show that ICDs should be placed in almost all patients who survive a potentially lethal arrhythmia (known as sudden death syndrome) as well as most patients with cardiomyopathies (diseased heart muscle) whose ejection fractions (EF) are less than 30% (normal being 60%).

The Maze Procedure

Atrial fibrillation is the most common cardiac arrhythmia.. Indeed, over 2 million people in the United States have atrial fibrillation.

Conceptual Design of the Maze Procedure

Atrial fibrillation is a complicated arrhythmia for which the cause is not completely understood.. The most common theory is that multiple circuit reentry causes the electric charges in the atrial chambers to go in all different directions.. Thus, the atrial chambers "fibrillate" instead of contracting in a uniform fashion.

Atrial fibrillation adversely effects the overall function of the heart and is associated with increase complications and increase risk of death.. For example, blood clots can form in the atrium because the atrial fibrillation just swirls the blood around in the chamber instead of ejecting it in a uniform manner.. These blood clots can break loose and travel to the brain causing a stroke.. Most patients with atrial fibrillation therefore require life-long anticoagulation with blood thinners such as Coumadin ®.

The Maze procedure was designed to interrupt the multiple reentrant circuits that causes the atrial chambers to fibrillate.

Cox-Maze Procedure

Dr. James L. Cox, the now retired Professor and Chairman, Department of Thoracic and Cardiovascular Surgery at Georgetown University Medical center is the father of surgery for atrial fibrillation.. Dr. Cox began developing operations to treat atrial fibrillation in the early 1980's.

The basic concept of the Cox-Maze procedure for atrial fibrillation was to create multiple incisions in the left and right atrium and then sew them back up immediately causing a full-thickness scar in the pattern of a maze.. The maze would interrupt the reentry circuit and force all of the electricity to go in one direction, just as if you were walking through a maze.

Radio-Frequency Maze Procedure

Incisions and Suturing for the original Cox-Maze Procedure

A recent advance in the Maze Procedure. has been the use of a variety of energy sources to create scars in the atria without the need to make incisions.  Radio-frequency energy is the most popular, but other energy sources include microwave, laser, and even freezing the tissue (cryo-ablation).

Eliminating all of the cutting and sewing in the atria greatly shortens and simplifies the operation and greatly reduces the risk.. Now, a complete Maze procedure using the radio-frequency technique can take as little as 20 minutes (not including the time to open and close the chest).

The most common indication for radio-frequency Maze procedure is during mitral valve repair, since many patients with mitral valve disease have developed atrial fibrillation.

Below is the equipment I use when I perform radio-frequency Maze procedure.. The machine generates the radio-frequency energy which is transmitted to a variety of instruments that are placed both inside and outside of the atria to create the Maze lesions.

Our experience with the Maze procedure is growing.. Minimally invasive approaches are being investigated as well as new instruments and energy sources.. This is certainly one of the most interesting and most exciting new areas of cardiac surgery.