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PACEMAKER
Pacemakers are the electrode devices that can be used to initiate the heartbeats when the heart’s intrinsic electric system cannot effectively generate a rate adequate to support cardiac output [due to damage or disease].
INDICATIONS:
When a patient has a temporary or permanent slower than normal impulse formation To control some tachydysrhythmia that don’t respond to medications. In case of symptomatic AV or ventricular conduction disturbance.
COMPONENTS:
Pulse generator: contains a standard 9-volt alkaline battery that provides the energy for sending electrical impulses to the heart & houses the circuitry that controls pacemaker operations. Pacemaker electrodes (leads): The pacing lead used for temporary pacing may be unipolar or bipolar. They sense cardiac depolarization & carry the impulse created by the generator to the heart. ▫ Endocardial leads ▫ Epicardial leads Most pacemaker have elective replacement indicator (ERI), a signal that indicates when the battery is approaching depletion. The pacemaker continues to work for several months after the appearance of ERI to ensure that there is adequate time for a battery replacement. Battery placement are usually performed using a local anesthetic, hospitalization is necessary for implantation or battery replacement.
TYPES OF PACEMAKER:
- Temporary pacemaker:
- Transvenous invasive pacemaker (endocardial pacing)
- Transthoracic invasive pacemaker (epicardial pacing)
- Transcutaneous non-invasive pacemaker
- Permanent pacemaker:
- Single chamber
- Dual chamber TEMPORARY PACEMAKER PERMANENT PACEMAKER Are intended for short-term use during hospitalization. They are used to support patients until they improve or reserve a permanent pacemakers. Permanent pacemakers are pacemaker that are intended for long-term use. Endocardial and the epicardial wires may be temporary. Endocardial leads are permanent. Its power source is located outside the body and may be taped to the skin or attached to a belt or the patient’s bed. The generator is implanted in a subcutaneous pocket usually over the pectoral muscle on the patient’s non- dominant side. They last approximately 6-12 years. The temporary generator size is about the size of a small paperbook. It weighs less than 1 oz. and is the size of a thick credit card.
Types of temporary pacemaker:
TRANSVENOUS INVASIVE
PACEMAKER (ENDOCARDIAL)
TRANSTHORACIC INVASIVE
PACEMAKER (EPICARDIAL)
TRANSCUTANEOUS NON-INVASIVE
PACEMAKER
It consists of lead/s that are threaded transvenously to the RA/RV and is attached to external power source. Five different veins can be used:
- Antecubital approach
- Femoral approach
- Subclavian approach
- Internal jugular
- External jugular It is achieved by attaching epicardial leads to the heart during heart surgery. The leads are passed through the chest wall and attached to the external power source. It is use to provide adequate HR and rhythm to the patient in an emergency situation. Indications of temporary pacemaker: Maintenance of adequate HR and rhythm during special circumstances such as surgery or post-op recovery, cardiac catheterization or coronary angiography. Before implantation of a permanent pacemaker. As prophylaxis after open heart surgery. Adequate anterior MI with 2 nd/ 3rd^ degree AV block/ bundle branch block. Acute inferior MI with symptomatic bradycardia and AV block.
Types of permanent pacemaker:
Single chamber system Dual-chamber system Only one pacing lead is implanted in either atrium or ventricle, depending on the chamber to be placed and sensed. Wires are placed in two chambers of the heart. One lead paces the atrium, one paces the ventricle. Closely resembles the natural pacing of the heart. Advantage: implantation of a single lead. Disadvantage :
- Single ventricular lead does not provide AV synchrony.
- Single ventricular lead does not provide ventricular backup if A-to-V conduction is lost. Advantages : - Provides AV synchrony - Lower incidence of AF - Lower risk of systemic embolism and stroke - Lower incidence new CHF - Lower mortality and higher survival rates. Indications of permanent pacemaker: Chronic AF with slow ventricular response. Hypersensitive carotid sinus syndrome Fibrotic or sclerotic changes of cardiac conduction system. Sick sinus syndrome Tachyarrhythmia 3 rd^ degree AV block
WORKING:
A pacemaker consists of a battery, a computerized generator and wires with sensors at their tips (called as electrodes). The battery powers the generator and both are surrounded by a thin metal box. The wires connect the generator to the heart.
- After venous access is obtained, a guide wire is advanced through the access needle, and the tip of the guide wire is positioned in the right atrium or the vena caval area under fluoroscopy. The needle is then withdrawn, leaving the guide wire in place. If indicated, a second access will be obtained in a similar fashion for positioning of a second guide wire.
- Sometimes, a double-wire technique is used, whereby 2 guide wires are inserted through the first sheath and the sheath then withdrawn, so that 2 separate sheaths can be advanced over the 2 guide wires. This technique can cause some resistance or friction during sheath or lead advancement.
2. Creation of pocket: A 1.5- to 2-inch incision is made in the infra-clavicular area parallel to the middle third of the clavicle, and a subcutaneous pocket is created with sharp and blunt dissection where the pacemaker generator will be implanted. Some physicians prefer to make the pocket first and obtain access later through the pocket or via venous cut-down; once access is obtained, they position the guide wires as described above. 3. Placement of lead(s): 1) Over the guide wire, a special peel-away sheath and dilator are advanced. The guide wire and dilator are withdrawn, leaving the sheath in place. 2) A stylet (a thin wire) is inserted inside the center channel of the pacemaker lead to make it more rigid, and the lead-stylet combination is then inserted into the sheath and advanced under fluoroscopy to the appropriate heart chamber. Usually, the ventricular lead is positioned before the atrial lead to prevent its dislodgment. 3) Making a small curve at the tip of the stylet renders the ventricular lead tip more maneuverable, so that it can more easily be placed across the tricuspid valve and positioned at the right ventricular apex. 4) Once the lead is secured in position, the introducing sheath is carefully peeled away, leaving the lead in place. After the pacing lead stylet is removed, pacing and sensing thresholds and lead impedances are measured with a pacing system analyzer, and pacing is performed at 10 V to make sure that it is not causing diaphragmatic stimulation. 5) After confirmation of lead position and thresholds, the proximal end of the lead is secured to the underlying tissue (i.e., pectoralis) with a non-absorbable suture that is sewn to a sleeve located on the lead. 6) If a second lead is indicated, it is positioned in the right atrium via a second sheath, with the lead tip typically positioned in the right atrial appendage with the help of a preformed J-shaped stylet. ▫ In a patient who is without an atrial appendage as a result of previous cardiac surgery, the lead can be positioned medially or in the lateral free wall of the right atrium. As with the ventricular lead, the atrial lead position is confirmed, impedance is assessed, the stylet is withdrawn, and the lead is secured to the underlying pectoralis with a non-absorbable suture. 4. Positioning of pulse generator When the leads have been properly positioned and tested and sutured to the underlying tissue, the pacemaker pocket is irrigated with antimicrobial solution, and the pulse generator is connected securely to the leads. Many physicians secure the pulse generator to underlying tissue with a non-absorbable suture to prevent migration or twiddler syndrome. Typically, the pacemaker is positioned superficial to the pectoralis, but occasionally, a subpectoral or inframammary position is required. After hemostasis is confirmed, a final look under fluoroscopy before closure of the incision is recommended to confirm appropriate lead positioning. 5. Completion and closure The incision is closed in layers with absorbable sutures and adhesive strips. Sterile dressing is applied to the incision surface. An arm restraint or immobilizer is applied to the unilateral arm for 12-24 hours to limit movement. A postoperative chest radiograph is usually obtained to confirm lead position and rule out pneumothorax. Before discharge on the following day, posteroanterior and lateral chest radiographs will be ordered again to confirm lead positions and exclude delayed pneumothorax.
Pain levels are typically low after the procedure, and the patient can be given pain medication to manage breakthrough pain associated with the incision site.
COMPLICATIONS:
- Local infection at the entry site of the leads for temporary pacing, or at the subcutaneous site for permanent generator placement
- Bleeding and hematoma at the entry site of the leads for temporary pacing, or at the subcutaneous site for permanent generator placement
- Phlebitis or thrombophlebitis
- Catheter related thrombosis
- Pneumothorax and hemothorax
- Failure to sense or capture
- Perforation of atrial/ventricular septum
- Ventricular ectopy and tachycardia from irritation of the ventricular wall by the endocardial electrodes
- Movement or dislocation of lead placed transvenously.
- Cardiac perforation resulting in pericardial effusion and rarely, cardiac tamponade, which may occur at the time of implantation or months later.
- Twiddler syndrome [As the leads move, they stop pacing the heart and can cause strange symptoms such as phrenic nerve stimulation resulting in abdominal pulsing or brachial plexus stimulation resulting in rhythmic arm twitching] may occur when the patient manipulates the generator, causing leads dislodgement or fracture of the leads.
- Pacemaker syndrome [hemodynamic instability caused by ventricular pacing and loss of AV synchrony.]
- Infection (endocarditis)
NURSING MANAGEMENT:
Assessment and prevention of pacemaker malfunction:
Three primary problems can occur with a pacemaker, these problems include failure to pace, failure to capture, failure to sense. Failure to pace occurs when pacemaker fails to initiate an electrical stimulus when it should fire, is noted by absence of pacer spikes on the rhythm strip. Causes:
- loose head hookups,
- Dead battery
- Malfunctioning pulse generator Interventions:
- Secure loose hookups
- Replace battery
- Replace pulse generator Failure to capture occurs when pacemaker generates an electrical impulse and no depolarization is noted. On the ECG a pacer spike is noted, but is not followed by a p wave or a QRS complex.
- When failure to capture occurs, nurse should adjust the output and place the patient on his/her left side to facilitate contact of a Transvenous pacing wire with the endocardium and septum (in temporary pacemaker). Causes:
- Pacemaker output too low
- Catheter dislodged
- Loose connections Intervention:
- Increase pacemaker output
- Reposition catheter
- Assess for dysrhythmias and treat as indicated.
- After implantation of the pacemaker, any physical activity should be minimized to prevent dislodgement of the pacing electrodes.
Patient education (limitations):
- Objects that contain magnets (e.g., the earpiece of the phone, large stereo speaker) shouldn’t be near the generator for longer than a few seconds.
- Advice the patient to place digital cellular phones, at least 6-12 inches (or on the opposite side) away from the pacemaker generator and not to carry them in a shirt pocket.
- Carry pacemaker information card at all times.
- Patient should be cautioned to avoid such situations or to simply move farther away from the area if they experience dizziness, or a feeling of rapid or irregular heartbeat.
- For the first few weeks after pacemaker implantation, arm shouldn’t be raised (the one closest to the pacemaker) above the level of your heart to let the area heal and keep the leads from moving.
- Tell them not to shower till 3 days; gently wash the incision site but don’t put lotion or powder on it.
- Tell all your healthcare provider, including your dentist that you have a pacemaker.
- For 1-2 months, don’t lift, push or pull anything that weighs more than 2.3 kg, including children.
- Report signs of pacemaker malfunction including dizziness, fainting, fatigue, weakness, chest pain, or palpitations.
- Avoid tight fitting clothing over the pacemaker site to reduce irritation and avoid skin breakdown.
CARDIAC RESYNCHRONIZATION THERAPY:
Cardiac resynchronization therapy (CRT), also referred to as biventricular pacing or multisite ventricular pacing, is a component of modern heart failure therapy for qualified patients. In CRT, there is a coronary sinus lead for left ventricular epicardial pacing in addition to a conventional right ventricular endocardial lead. By simultaneously pacing the right and left ventricles, CRT reduces the ventricular dyssynchrony that is frequently present in patients with ventricular dilatation or conduction system defect. CRT can involve either pacing (CRT-P) or defibrillation (CRT-D).
