CARDIAC PACEMAKER Ms. Saranya N 27-Feb-18 Cardiac Pacemaker

Implantable Pacemaker Systems Contain the Following Components: Lead wire(s) Implantable pulse generator (IPG) A basic pacing system is made up of: Implantable pulse generator that contains: A power source—the battery within the pulse generator that generates the impulse Circuitry—controls pacemaker operations Leads—Insulated wires that deliver electrical impulses from the pulse generator to the heart. Leads also transmit electrical signals from the heart to the pulse generator. Electrode—a conductor located at the end of the lead; delivers the impulse to the heart. 27-Feb-18 Cardiac Pacemaker

Pacemaker Components Combine with Body Tissue to Form a Complete Circuit Pulse generator: power source or battery Leads or wires Cathode (negative electrode) Anode (positive electrode) Body tissue Lead IPG In a bipolar system, body tissue is part of the circuit only in the sense that it affects impedance (at the electrode-tissue interface). In a unipolar system, contact with body tissue is essential to ground the IPG and allow pacing to occur. Anode Cathode 27-Feb-18 Cardiac Pacemaker

The Pulse Generator: Contains a battery that provides the energy for sending electrical impulses to the heart Houses the circuitry that controls pacemaker operations Circuitry Lithium-iodine is the most commonly used power source for today’s pacemakers. Microprocessors (both ROM and RAM) control sensing, output, telemetry, and diagnostic circuits. Battery 27-Feb-18 Cardiac Pacemaker

Leads Are Insulated Wires That: Deliver electrical impulses from the pulse generator to the heart Sense cardiac depolarization Lead 27-Feb-18 Cardiac Pacemaker

During Pacing, the Impulse: Impulse onset Begins in the pulse generator Flows through the lead and the cathode (–) Stimulates the heart Returns to the anode (+) * During pacing, the electrical impulse: Begins in the pulse generator Flows through the cathode (negative electrode) Stimulates the heart tissue Returns through the body tissue to the anode (positive electrode) This pathway forms a complete pacing circuit. 27-Feb-18 Cardiac Pacemaker

Flows through the tip electrode (cathode) A Unipolar Pacing System Contains a Lead with Only One Electrode Within the Heart; In This System, the Impulse: Flows through the tip electrode (cathode) Stimulates the heart Returns through body fluid and tissue to the IPG (anode) + Anode In the unipolar system, the impulse: Travels down the lead wire to stimulate the heart at the tip electrode also referred to as the cathode (–) Returns to the metal casing of the impulse generator or the anode (+) by way of body fluids The flow of the impulse makes a complete circuit. - Cathode 27-Feb-18 Cardiac Pacemaker

Flows through the tip electrode located at the end of the lead wire A Bipolar Pacing System Contains a Lead with Two Electrodes Within the Heart. In This System, the Impulse: Flows through the tip electrode located at the end of the lead wire Stimulates the heart Returns to the ring electrode above the lead tip The impulse: Travels down the lead wire to stimulate the heart at the tip electrode, which is the cathode (–) Travels to the ring electrode, which is the anode (+), located several inches above the lead tip Returns to the pulse generator by way of the lead wire Anode Cathode 27-Feb-18 Cardiac Pacemaker

Most Pacemakers Perform Four Functions: Stimulate cardiac depolarization Sense intrinsic cardiac function Respond to increased metabolic demand by providing rate responsive pacing Provide diagnostic information stored by the pacemaker The modern pacemaker supports heart function in the following ways: Provides effective and consistent cardiac depolarization Prevents unnecessary pacing by sensing cardiac activity Increases rate to meet increased metabolic demand Provides information about how the patient’s heart and the implanted pacemaker are functioning 27-Feb-18 Cardiac Pacemaker

Types 1. Asynchronous/Fixed Rate 2. Synchronous/Demand 3. Single/Dual Chamber Sequential (A & V) 4. Programmable/nonprogrammable 27-Feb-18 Cardiac Pacemaker

Single-Chamber System The pacing lead is implanted in the atrium or ventricle, depending on the chamber to be paced and sensed 27-Feb-18 Cardiac Pacemaker

Advantages and Disadvantages of Single-Chamber Pacing Systems Implantation of a single lead Single ventricular lead does not provide AV synchrony Single atrial lead does not provide ventricular backup if A-to-V conduction is lost Pacing in the VVI/R mode and loss of AV synchrony can lead to pacemaker syndrome. Pacemaker syndrome can be defined as “an assortment of symptoms related to the adverse hemodynamic impact from the loss of AV synchrony.” Atrial pacemakers should only be used with patients who have proven AV conduction and regular follow-up testing available. 27-Feb-18 Cardiac Pacemaker

Dual-Chamber Systems Have Two Leads: One lead implanted in the atrium One lead implanted in the ventricle 27-Feb-18 Cardiac Pacemaker

Benefits of Dual Chamber Pacing Provides AV synchrony Lower incidence of atrial fibrillation Lower risk of systemic embolism and stroke Lower incidence of new congestive heart failure Lower mortality and higher survival rates Studies have been done that demonstrate the differences in outcome, hemodynamic improvement, and quality of life assessment by using AV synchronous, or "atrial-based," pacing modes instead of VVI/R. Some of the benefits of using an atrial-based pacing mode include: AV synchrony–Clinical benefits such as increased cardiac output, augmentation of ventricular filling (especially important for the majority of the pacing population with LVD and reduced compliance from effects of aging). Providing AV synchrony minimizes valvular regurgitation, and preserves atrial electrical stability. In the Framingham Study, the development of chronic AF was associated with a doubling of overall mortality and of mortality from cardiovascular disease (Kannel, 1982) The following emphasize the importance of preventing atrial fibrillation: Patients with AF unrelated to rheumatic or prosthetic valvular disease have a risk of ischemic stroke about five times higher than those with normal sinus rhythm. AF is associated with over 75,000 cases of stroke per year. See bibliography for listing of studies cited. 27-Feb-18 Cardiac Pacemaker

PACEMAKER MODE? 27-Feb-18 Cardiac Pacemaker

PACEMAKER MODE? 27-Feb-18 Cardiac Pacemaker

PACEMAKER MODE? 27-Feb-18 Cardiac Pacemaker

WHAT IS HAPPENING HERE? 27-Feb-18 Cardiac Pacemaker

WHAT IS HAPPENING HERE? 27-Feb-18 Cardiac Pacemaker

THANK YOU 27-Feb-18 Cardiac Pacemaker