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What is a Transvenous Pacemaker?
A transvenous pacemaker is an electronic device that is passed through a large vein (typically a neck or inguinal vein) as it is implanted on the heart for the purpose of regulating its rate and rhythm.
In order for the heart to be able to pump a constant supply of blood to the body, it has to contract and relax rhythmically within a normal range, typically at 60 to 100 beats per minute. However, many factors such as age, disease, activity, substances and others can affect heart rate, causing it to decrease or increase inadvertently. This can be a temporary phenomenon, and compensatory mechanisms in the body are brought about to sustain a normal supply of blood to the vital organs like the brain and kidneys.
However, serious conditions may occur, causing arrhythmia, when the number and rhythm of heart beats severely decline for a long time resulting in a compromise in blood supply to the vital organs complications. These may lead to organ failure and death. Emergency measures must then be done to keep the heart beating at a normal rate and rhythm. When medications such as atropine and epinephrine cannot sustain the heart for a long time, an emergency pacemaker implantation may be done as a life-saving procedure.
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Indications for Pacemaker Implantation
Generally, a transvenous pacemaker is used for situations when heart rhythm renders a hemodynamically unstable blood supply which compromises organ function. This occurs in the following conditions:
- Acute myocardial infarction or heart attack
- Dangerously low heart rate and rhythm, or bradyarrhythmia not responsive to medications
- Conduction abnormalities in the heart muscles, or atrioventricular (AV) blocks
- Diffuse scarring of heart muscles, causing electrical conduction abnormalities in the heart
- Defects in the sinus nodal function – the sinus node is the natural, automatic pacemaker of the heart
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How a Pacemaker Works
Wires are inserted through the large veins of the neck (the subclavian or the internal jugular vein) or of the groin (femoral vein), and these contact directly the right side of the heart (either the first or second chamber, which is the atrium or ventricle, respectively). This is done in the emergency room, cardiac catheterization lab or hospital bedside with fluoroscopic or electrocardiographic guidance. Light sedation and local anesthesia are given to the patient to provide comfort.
The wires are connected externally to a pulse generator which is the source of regular and rhythmic pulses. Confirmation of placement inside the heart is done with x-rays.
The electrical output of the device is supplied by a fresh battery that controls the amount and rate of energy. The electrical impulse in turn is “captured” and the cardiac muscle in turn contracts to initiate the pumping of the heart.
Once the temporary pacemaker is in place, baseline ECG is taken together with vital signs. These are also monitored regularly to make sure there is hemodynamic stability. The need for a permanent pacemaker may be assessed later.
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Compared to an external or cutaneous pacemaker, transvenous pacemakers take longer to apply. Complications may also occur such as:
- Pneumothorax – when the lung is injured and causes a collection of air between the lungs and the thoracic wall
- Hemothorax – injury that causes bleeding inside the chest
- Hematoma – results from uncontrolled bleeding so that blood collects outside the blood vessels
- Air embolism – results from air being absorbed into the blood vessel
- Infection at the insertion site
- Pericarditis – collection of fluid around the heart
- Complications in heart rhythm – require immediate attention and adjustment in the pacemaker
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Caring for a Patient with a Pacemaker
Goals for nursing care for these patients include:
- Preventing accidental dislodgement of the wires and electrodes
- Monitoring vital signs, level of consciousness and hemodynamic stability
- Checking for bleeding, redness, infection
- Observation of cardiac rate and rhythm, capture and sensitivity threshold testing to make sure the pacemaker is working properly
The use of transvenous pacemakers as a temporary means of stabilizing cardiac function requires expertise in its implantation and post-operative care. It involves medical and nursing skills that are vital to its effective functioning and in saving the life of a compromised patient.
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Chest, “Temporary Transvenous Cardiac Pacing in the Critical Care Setting”, http://chestjournal.chestpubs.org/content/93/3/607.full.pdf+html?ijkey=733fe7b08868c1b464def2590fd49bc1b8ff04d6&keytype2=tf_ipsecsha
Nursing Center, "Caring for a Patient with a Temporary Pacemaker", http://www.nursingcenter.com/prodev/ce_article.asp?tid=841729