Pacemakers and Implanted Defibrillators Mike Harlan

History Pacemakers Pacemakers –It is believed that Dr. Albert Hyman was inventor of first pacemaker –First fully functional wearable pacemaker developed in 1957 –First implanted pacemaker 1960 ICD’s ICD’s –First implantable ICD developed by Michel Mirowski, first used in a human in 1980 –FDA approved use of ICD’s in 1985

Artificial Pacemakers An internal artificial pacemaker is a small battery-operated device that helps the heart beat in a regular rhythm An internal artificial pacemaker is a small battery-operated device that helps the heart beat in a regular rhythm An electrode is placed next to the heart wall, and small electrical charges travel through the wire to the heart (usually the right side), causing it to contract. An electrode is placed next to the heart wall, and small electrical charges travel through the wire to the heart (usually the right side), causing it to contract. Most modern pacemakers have a sensing device that turns the pacemaker off when the natural heartbeat is above a certain level Most modern pacemakers have a sensing device that turns the pacemaker off when the natural heartbeat is above a certain level

Types of Pacemakers Fixed-rate – fires continuously at a preset rate Fixed-rate – fires continuously at a preset rate Demand – contain a sensing device, fire only when heart rate drops below a set rate Demand – contain a sensing device, fire only when heart rate drops below a set rate Dual-chambered – stimulates the atria first and then the ventricle Dual-chambered – stimulates the atria first and then the ventricle

Pacemaker Indications Absolute Indications Absolute Indications –Sick sinus rhythm –Symptomatic sinus bradycardia –Tachy-brady syndrome –Atrial Fibrillation with slow ventricular response –Third Degree Heart Block –Chronotropic incompetence –Prolonged QT syndrome

Relative Indications Relative Indications –Cardiomyopathy –Severe refractory neurocardiogenic syncope –Paroxysmal atrial fibrillation Results of a recent study showed that pt’s with pacemakers had a one-year recurrence rate of syncope of 19%, compared to 60% of pt’s in the control group Results of a recent study showed that pt’s with pacemakers had a one-year recurrence rate of syncope of 19%, compared to 60% of pt’s in the control group

Pacemaker Complications Infection Infection Thrombophlebitis Thrombophlebitis –Blood clot causes inflammation in vein Pacemaker Syndrome Pacemaker Syndrome –Phenomenon where a pt. feels worse after pacemaker placement and presents with progressive worsening of symptoms of CHF Failure to output Failure to output Failure to capture Failure to capture Failure to sense correctly Failure to sense correctly

Internal Cardiac Defibrillators ICD’s have wires connecting to one or more heart chambers. The wires monitor heart rhythm and deliver shocks to the heart when abnormal rhythm is sensed. ICD’s have wires connecting to one or more heart chambers. The wires monitor heart rhythm and deliver shocks to the heart when abnormal rhythm is sensed. Single chamber ICD’s – wires connect to one or both ventricles Single chamber ICD’s – wires connect to one or both ventricles Dual-chamber ICD’s – wires connect to both an atrium and a ventricle Dual-chamber ICD’s – wires connect to both an atrium and a ventricle Wires of an ICD connect to small metal box that contains a battery, pulse generator, and computer Wires of an ICD connect to small metal box that contains a battery, pulse generator, and computer ICD’s are indicated for pt’s with hx of life-threatening ventricular tachyarrhythmias or VF ICD’s are indicated for pt’s with hx of life-threatening ventricular tachyarrhythmias or VF A recent study showed that pt’s that received an ICD had a 31% reduction in mortality rate. A recent study showed that pt’s that received an ICD had a 31% reduction in mortality rate.

ICD complications Most common problem is that they shock when not needed. This can damage the heart or trigger an irregular heartbeat Most common problem is that they shock when not needed. This can damage the heart or trigger an irregular heartbeat Swelling, bruising, or infection after surgery Swelling, bruising, or infection after surgery

Treatment of pt’s with pacemakers or ICD’s The presence of a pacemaker or ICD does not alter the emergency treatment of patients The presence of a pacemaker or ICD does not alter the emergency treatment of patients Defibrillation, cardioversion, and pacing can be performed on pt’s with pacemakers or ICD’s Defibrillation, cardioversion, and pacing can be performed on pt’s with pacemakers or ICD’s –Try to place pads a safe distance (10cm) from a pacemaker or ICD if possible, but don’t delay treatment –A magnet can be placed over the pulse generator to reset the pacemaker to a predetermined rate. This is indicated if a pt. has a runaway pacemaker

References Bledsoe B, Porter R, Cherry R. Essentials of Paramedic Care. Second Edition. Prentice Hall; 2007 Bledsoe B, Porter R, Cherry R. Essentials of Paramedic Care. Second Edition. Prentice Hall; Gregoratos G, Indications and Recommendations for Pacemaker Therapy. American Family Physician, 2005 Gregoratos G, Indications and Recommendations for Pacemaker Therapy. American Family Physician, 2005