Pacemakers

Indications for permanent pacemaker therapySinus node dysfunctionSick sinus syndromeThird degree heart block Fibrosis or sclerotic changes in the conducting systemTachyarrhythmiasChronic Atrial Fibrillation with slow ventricular response.Heart Failure

A pacemaker is a battery powered, electronic device used to stimulate the heart to depolarize and contract.Usually named according to where the electrodes are located and the route the electrical current takes to the heart

A pacemaker consist of a (1) generator (battery) which creates the electrical stimulus: (2) a connector where the leads attach: and, (3) one or two lead wires that carry the signals to the heart muscle.

Pacing may be permanent or temporary.Temporary pacerLocated externally transvenous, epicardial, or transcutaneous

Transvenous

Stimulates the endocardium of the right atrium or ventricle by means of electrode into central vein (subclavian or cephalic vein)

Uses for Temp Pacer Cath, angioplasty, CABG, eletrophysiological studies

MI

Tachyarrhythmias

Epicardial implantationTakes longer and requires more recovery time. A opening is made in the lower chest and the lead is threaded up to the outside of the heart. The generator is attached to the leads and placed underneath the skin in the abdomen.

Transcutaneous

Pads are placed on the anterior and posterior chest wallPads have a connecting cable that is attached to a bed side Zoll/Pacer Defibrillation machine Used for Quick , bedside emergent needs for pacing- not long term patients unresponsive to atropineOnce pads are on patient This is done until capture, then rate is dialed up to 30-125 BPMEnergy level is selected with MA (milliamps) 25-50 mA usually upper limits 82 mAMay need to provide sedation for patient- related to feeling of pacingAlso oxygen, IV access, and EKG monitoring

Implanting the PacemakerTypically done in the OR or Cath Lab under local anesthesia. An incision is made into the skin just under the clavicle and a small pocket it is created . The lead wires are threaded through the incision into the subclavian (transvenous) to the heart. The leads are attached to the generator and the generator placed in the subcu pocket. The pacemaker is then programmed.

Care of PacerLocation of right or left is determined by hobbies, occupation, or patients handednessPrevent Infection- usually keep clean and dry, if instructed to wash use antibacterial soap and water, pat dryAvoid lotions, creams, or powdersAvoid hyperextension of arm (allows for leads to secure)Avoid straps- bras, seatbelts, avoid driving

Care after PacerBed rest for few hours related to sedation Cardiac monitor- to be sure the pacer is functioningProphylactic antibiotic

TeachingFor at least one week

Patient may return to daily activities but take it easy (no heavy lifting, running, contact sports).The arm on the operative side should not be raised over the head.

Dont hit or rub the insertion site.

Patient should take his temp and inspect the site for signs of infection.

Stitches out in 1 -2 weeks. Return to work in 1 2 weeks.

Risks/ComplicationsBleeding or hematomaTearing of the vein or artery wallThrombusEmbolusPuncture of the lung or heart muscleNerve damageInfectionPacemaker malfunction

Single chamber

Dual chamber

CodingA 3 letter code has been developed to describe the various pacemakers. First letter -- the chamber paced: V(ventricle), A(atrium), or D(dual or double). Second letter -- chamber sensed: V(ventricle), A(atrium), D(double), or 0 (none). Third letter mode of response to sensing: T(triggered), I(inhibited), or D(double). SoVVI means that the ventricle is paced, the ventricle is sensed, and the pacer is inhibited by a sensed beat.

Third Letter3rd position - I (inhibited), the mode of response is to withhold a pacemaker output in the presence of a sensed event- patients event. In a VVI pacemaker, the pacemaker senses a ventricular event and withholds the ventricular output. If the pacemaker is programmed to the DDI mode, the pacemaker simply inhibits the output of the device in the chamber where any signal is sensed. In the presence of fast atrial rates and heart block, the DDI pacemaker rhythm resembles a VVI pacemaker.

The letter D (dual) in the third position indicates that the device will respond to the sensed signal by either inhibiting the pacemaker response, tracking the sensed event, or inhibiting the output on the sensed channel and triggering an output to maintain AV synchrony. The most common example of the letter D in the 3rd position can be seen with DDD pacemakers. A sensed atrial signal will cause the device to inhibit the atrial output, a timer then starts that will cause a triggered ventricular output after a certain interval. If the patient has an intrinsic R wave during the triggering interval, the pacemaker will inhibit the ventricular output.

Modes of PacingDemand- (Synchronous) PM that discharges only when patients heart rate drops below the preset rateFixed rate- (Asynchronous) pacemaker- PM that continuously discharges at present rate regardless of the patients intrinsic activityRate adaptive- changes with activity

Checking the Pacemaker

Routine office visits with EKG

Pacemaker can be checked from home

From time to time the pacemaker settings may need to be adjusted

Teaching contd Carry an ID card and show it to any doctor, dentist, etc that you see. Also may need to present to security personnel (airport, library, department store).Exercise regularly ( swimming, biking, jogging)avoid activities like racquetball and contact sports.Modern pacemakers are well protected from outside signal. Microwaves, hairdryers, power tools, computers, TV, radio, electric blankets, heating pads are OK.Avoid very strong magnets such MRI, heavy duty electrical equipment, ham radios, radio transmitting towers.Cell phones may cause problems. Hold them to the ear opposite the pacemaker.

Cardiac Resynchronization Therapy (CRT)

Both ventricles (biventricular) are paced to resynchronize the cardiac cycle resulting in improved cardiac function.

Ventricular Pacing

*

Ventricular pacing

100% ventricular paced*

V Pacing

AV Pacing

Pacemaker MalfunctionFailure to sense (pacer lead fracture, battery failure, movement of the electrode) PM fails to recognize spontaneous myocardial depolarizationFailure to capture (pacer lead fracture, battery failure, movement of the electrode, fibrosis at the catheter tip) inability of pacer to depolarize the myocardiumFailure to Pace- (failure to fire)- failure to procedure an electrical stimulus or impulse when needed or correct number of impulse

Failure to sense

PM fails to recognize spontaneous myocardial depolarization

Failure to Capture

Inability of pacer to depolarize the myocardium

Failure to pace (Fire)

failure to procedure an electrical stimulus or impulse when needed or correct number of impulse

Troubleshoot New or temporary pacemakerFailure to SenseFailure to Capture

*100% ventricular paced*