Electrophysiology

Cardiac Lead

Cardiac Lead Removal is the extraction of one or more leads. Your doctor may have determined that your lead(s) should be removed for one of the following reasons: The lead is damaged The lead requires more energy to function than the device (pacemaker or ICD) is able to deliver There is an infection at the implant site of the lead The lead is interfering with blood flow back to the heart The lead is interfering with other leads or may interfere with new lead(s) that need to be placed in your heart

Uncoordinated Contractions

When there is a delay in electrical signal transmission through the left bundle branch, this causes left bundle branch block (LBBB). Because the electrical signal to the left ventricle is delayed, the right ventricle begins to contract a fraction of a second before the left ventricle, instead of simultaneously. The result is an asynchronous, or uncoordinated contraction of the ventricles and a mis-timing in the contraction pattern of the left atrium and ventricle. Other conduction abnormalities, such as right bundle branch block (RBBB), also may contribute to less efficient contraction of the heart. This further reduces the pumping ability of the already weakened heart muscle.

Congestive Heart Failure

Coronary artery disease and heart attacks are the most frequent causes of CHF, but inherited disorders, viral infections and toxins, such as alcohol, also can cause heart muscle damage. Symptoms of CHF typically include shortness of breath, swelling of the feet and legs, abdominal swelling, fatigue, exercise intolerance, diminished appetite and depression. Most often, medications aim to control CHF symptoms, such as the buildup of excess fluid that causes leg swelling and makes it difficult to breath. Medications can reduce fluid retention, strengthen the heart’s squeezing ability and relax blood vessels, thereby reducing the resistance to blood flow and easing the heart’s workload. In addition, lifestyle changes, such as low-salt diets and exercise, can help control symptoms.

Heart Beat

The normal heartbeat originates in a section of the right atrium known as the sinoatrial, or SA node. The electrical signal from the sinoatrial node spreads through both atria causing them to contract and squeeze blood into the ventricles. The electrical signal then passes through an electrical bridge known as the atrioventricular or AV node. After a split second delay, the signal continues to the ventricles by way of a specialized network known as the left and right bundle branches. The bundle branches separate to the left and right ventricles, which enables the electrical signal to stimulate both ventricles simultaneously. This coordinated contraction, or squeezing, of the ventricles is necessary for optimal pumping of blood to the body and lungs.

Cardiac Resynchronization Therapy

The leads electrically stimulate heart muscle to synchronize the contractions of the heart’s two lower chambers, or ventricles. Only when the lower chambers beat in harmony can they contract with enough force to push blood carrying oxygen through the body. More than 22 million people worldwide suffer from congestive heart failure (CHF), a potentially debilitating disease. Until recently, lifestyle changes, medication and, sometimes, heart surgery were the only treatment options. Patients with severe symptoms, however, received little, if any, relief from such approaches. To make matters worse, up to 40 percent of patients with CHF also have an arrhythmia that further reduces the heart’s ability to beat properly. Cardiac resynchronization therapy (CRT) is an innovative new therapy that can relieve CHF symptoms by improving the coordination of the heart’s contractions.CRT builds on the technology used in pacemakers and implantable cardioverter devices. CRT devices also can protect the patient from slow and fast heart rhythms. The concept behind CRT is quite simple. Resynchronization restores the normal coordinated pumping action of the ventricles by overcoming the delay in electrical conduction caused by bundle branch block. This is accomplished by means of a special type of cardiac device. These powerful, “built-in” devices have enormous potential to improve the quality of life and probably survival for patients with heart failure.  

Sudden Cardiac Death

A heart attack occurs when a partial or complete vessel blockage interferes with the ability of blood to flow to the heart, and heart muscle dies. Cardiac arrest, or sudden cardiac death (SCD), is NOT a heart attack, but a prior heart attack can put someone at risk for SCD. SCD is the result of an “electrical problem” in the conduction system that regulates the normal, rhythmic contractions of the heart muscle that pumps blood throughout the body. In SCD, the electrical signals that regulate the pumping action of the lower chambers of the heart (ventricles) suddenly and without warning become rapid and chaotic. When the rhythmic contractions of the ventricles stop, the heart can’t pump blood. The brain is starved of oxygen, and the individual loses consciousness in seconds. The heart cannot recover on its own from VF. Unless immediate emergency help is available, death follows in minutes.

ICD (Implantable Cardioverter Debrillators)

Almost everyone has seen a physician on television, paddles in hand, yelling “Clear!”, then applying those paddles to the chest of a patient to shock him “back to life”. As dramatic as the scene may be, defibrillation, or shock, can be the only way to stop certain deadly heart arrhythmias before they kill. For those who are at high risk of the deadliest forms of arrhythmias – ventricular tachycardia and ventricular fibrillation – an internal “shocking” device may provide the best defense against sudden cardiac arrest. Such a device, known as an implantable cardioverter defibrillator (ICD), is considered effective in fighting cardiac arrest over 90 percent of the time, an astounding success for a condition that few survived as recently as 15 years ago. ICDs are pacemaker-like devices that continuously monitor the heart rhythm, and deliver life-saving shocks if a dangerous heart rhythm is detected. They can significantly improve survival in certain groups of patients with heart failure who are at high risk of ventricular fibrillation (VF). Modern ICD devices have an electronic memory that records the electrical patterns of the heart whenever an abnormal heart beat, or arrhythmia occurs. This record is available for review during regular checkups by the physician, who can monitor the frequency and severity of problems in the heart’s electrical conduction system that may lead to cardiac arrest or other serious heart disorders.

Cardiac Pacing

The first electrical signal comes from the heart’s own natural pacemaker, the sinoatrial node, comprised of electrically active cells and located in the upper right heart chamber. This node sends a steady stream of electrical signals along a pathway through the heart’s upper chambers. The signals then travel to the electrical bridge – the atrioventricular node – between the upper and lower chambers and, finally, move to the lower chambers. A problem at any point in the electrical pathway can wreak havoc with the regular beating of a heart. Luckily, an artificial pacemaker – a small, battery -operated device – can take over the role of the heart’s own electrical system, if necessary.

Cardiac Ablation

In cardiac ablation, a form of energy renders a small section of damaged tissue inactive. This puts an end to arrhythmias that originated at the problematic site. Normally, electricity flows throughout the heart in a regular, measured pattern. This normally operating electrical system is the basis for heart muscle contractions.
Sometimes, the electrical flow gets blocked or travels the same pathways repeatedly creating something of a “short circuit” that disturbs normal heart rhythms. Medicine often helps. In some cases, however, the most effective treatment is to destroy the tissue housing the short circuit. This procedure is called cardiac ablation. Cardiac ablation is just one of a number of terms used to describe the non-surgical procedure. Other common terms are: cardiac catheter ablation, radiofrequency ablation, cardiac ablation, or simply ablation.