Transcutaneous pacing
Encyclopedia
Transcutaneous pacing is a temporary means of pacing a patient's heart
during a medical emergency. It is accomplished by delivering pulses of electric current through the patient's chest, which stimulates the heart
to contract.
The most common indication
for transcutaneous pacing is an abnormally slow heart rate
. By convention, a heart rate of less than 60 beats per minute in the adult patient is called bradycardia
. Not all instances of bradycardia require medical treatment. Normal heart rate varies substantially between individuals, and many athletes in particular have a relatively slow resting heart rate. In addition, the heart rate is known to naturally slow with age. It is only when bradycardia presents with signs and symptoms of shock that it requires emergency treatment
with transcutaneous pacing.
Some common causes of hemodynamically
significant bradycardia include acute myocardial infarction
, sinus node dysfunction
and complete heart block. Transcutaneous pacing is no longer indicated for the treatment of asystole
(cardiac arrest
associated with a "flat line" on the ECG
), with the possible exception of witnessed asystole (as in the case of bifascicular block
that progresses to complete heart block
without an escape rhythm).
During transcutaneous pacing, pads are placed on the patient's chest, either in the anterior/lateral position or the anterior/posterior position. The anterior/posterior position is preferred as it minimizes transthoracic electrical impedance
by "sandwiching" the heart between the two pads. The pads are then attached to a monitor/defibrillator, a heart rate is selected, and current (measured in milliamps) is increased until electrical capture (characterized by a wide QRS complex
with tall, broad T wave on the ECG
) is obtained, with a corresponding pulse. Pacing artifact on the ECG and severe muscle twitching may make this determination difficult. It is therefore advisable to use another instrument (e.g. SpO2 monitor or bedside doppler) to confirm mechanical capture.
Transcutaneous pacing may be uncomfortable for the patient. Sedation
should therefore be considered. Before pacing the patient in a prehospital setting sedation is recommended by administering an analgesic or an anxioloytic. Prolonged transcutaneous pacing may cause burns on the skin. According to the Zoll M Series Operator's Guide," Continuous pacing of neonates can cause skin burns. If it is necessary to pace for more than 30 minutes, periodic inspection of the underlying skin is strongly advised." It is meant to stabilize the patient until a more permanent means of pacing is achieved.
Other forms of cardiac pacing are transvenous pacing
, epicardial pacing, and permanent pacing with an implantable pacemaker
.
In addition to synchronozied transcutaneous pacing offered by newer cardiac monitor/defibrillators there is also an option for Asynchronous Pacing. Sometimes in the prehospital setting a situation may arise where ECG electrodes are not available or something interferes with their adhesion to the patient's skin. In these rare situations where the patient must be paced and there are no other alternatives Asynchronous Pacing may be used. Again this setting should only be used as a last resort due to possible adverse cardiac effects it could cause.
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
during a medical emergency. It is accomplished by delivering pulses of electric current through the patient's chest, which stimulates the heart
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
to contract.
The most common indication
Indication (medicine)
In medicine, an indication is a valid reason to use a certain test, medication, procedure, or surgery. The opposite of indication is contraindication.-Drugs:...
for transcutaneous pacing is an abnormally slow heart rate
Heart rate
Heart rate is the number of heartbeats per unit of time, typically expressed as beats per minute . Heart rate can vary as the body's need to absorb oxygen and excrete carbon dioxide changes, such as during exercise or sleep....
. By convention, a heart rate of less than 60 beats per minute in the adult patient is called bradycardia
Bradycardia
Bradycardia , in the context of adult medicine, is the resting heart rate of under 60 beats per minute, though it is seldom symptomatic until the rate drops below 50 beat/min. It may cause cardiac arrest in some patients, because those with bradycardia may not be pumping enough oxygen to their heart...
. Not all instances of bradycardia require medical treatment. Normal heart rate varies substantially between individuals, and many athletes in particular have a relatively slow resting heart rate. In addition, the heart rate is known to naturally slow with age. It is only when bradycardia presents with signs and symptoms of shock that it requires emergency treatment
Emergency medicine
Emergency medicine is a medical specialty in which physicians care for patients with acute illnesses or injuries which require immediate medical attention. While not usually providing long-term or continuing care, emergency medicine physicians diagnose a variety of illnesses and undertake acute...
with transcutaneous pacing.
Some common causes of hemodynamically
Hemodynamics
Hemodynamics, meaning literally "blood movement" is the study of blood flow or the circulation.All animal cells require oxygen for the conversion of carbohydrates, fats and proteins into carbon dioxide , water and energy in a process known as aerobic respiration...
significant bradycardia include acute myocardial infarction
Myocardial infarction
Myocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...
, sinus node dysfunction
Sick sinus syndrome
Sick sinus syndrome, also called sinus node dysfunction, is a group of abnormal heart rhythms presumably caused by a malfunction of the sinus node, the heart's primary pacemaker...
and complete heart block. Transcutaneous pacing is no longer indicated for the treatment of asystole
Asystole
In medicine, asystole is a state of no cardiac electrical activity, hence no contractions of the myocardium and no cardiac output or blood flow...
(cardiac arrest
Cardiac arrest
Cardiac arrest, is the cessation of normal circulation of the blood due to failure of the heart to contract effectively...
associated with a "flat line" on the ECG
Electrocardiogram
Electrocardiography is a transthoracic interpretation of the electrical activity of the heart over a period of time, as detected by electrodes attached to the outer surface of the skin and recorded by a device external to the body...
), with the possible exception of witnessed asystole (as in the case of bifascicular block
Bifascicular block
Bifascicular block is a conduction abnormality in the heart where two of the three main fascicles of the His/Purkinje system are blocked.Most commonly, it refers to a combination of right bundle branch block and either left anterior fascicular block or left posterior fascicular block , with the...
that progresses to complete heart block
Third degree heart block
-Presentation:Third-degree AV block, also known as complete heart block, is a medical condition in which the impulse generated in the SA node in the atrium does not propagate to the ventricles....
without an escape rhythm).
During transcutaneous pacing, pads are placed on the patient's chest, either in the anterior/lateral position or the anterior/posterior position. The anterior/posterior position is preferred as it minimizes transthoracic electrical impedance
Electrical impedance
Electrical impedance, or simply impedance, is the measure of the opposition that an electrical circuit presents to the passage of a current when a voltage is applied. In quantitative terms, it is the complex ratio of the voltage to the current in an alternating current circuit...
by "sandwiching" the heart between the two pads. The pads are then attached to a monitor/defibrillator, a heart rate is selected, and current (measured in milliamps) is increased until electrical capture (characterized by a wide QRS complex
QRS complex
The QRS complex is a name for the combination of three of the graphical deflections seen on a typical electrocardiogram . It is usually the central and most visually obvious part of the tracing. It corresponds to the depolarization of the right and left ventricles of the human heart...
with tall, broad T wave on the ECG
Electrocardiogram
Electrocardiography is a transthoracic interpretation of the electrical activity of the heart over a period of time, as detected by electrodes attached to the outer surface of the skin and recorded by a device external to the body...
) is obtained, with a corresponding pulse. Pacing artifact on the ECG and severe muscle twitching may make this determination difficult. It is therefore advisable to use another instrument (e.g. SpO2 monitor or bedside doppler) to confirm mechanical capture.
Transcutaneous pacing may be uncomfortable for the patient. Sedation
Sedation
Sedation is the reduction of irritability or agitation by administration of sedative drugs, generally to facilitate a medical procedure or diagnostic procedure...
should therefore be considered. Before pacing the patient in a prehospital setting sedation is recommended by administering an analgesic or an anxioloytic. Prolonged transcutaneous pacing may cause burns on the skin. According to the Zoll M Series Operator's Guide," Continuous pacing of neonates can cause skin burns. If it is necessary to pace for more than 30 minutes, periodic inspection of the underlying skin is strongly advised." It is meant to stabilize the patient until a more permanent means of pacing is achieved.
Other forms of cardiac pacing are transvenous pacing
Transvenous pacing
Transvenous cardiac pacing, also called endocardial pacing, is a potentially life saving intervention used primarily to correct profound bradycardia. It can be used to treat symptomatic bradycardias that do not respond to transcutaneous pacing or to drug therapy...
, epicardial pacing, and permanent pacing with an implantable pacemaker
Artificial pacemaker
A pacemaker is a medical device that uses electrical impulses, delivered by electrodes contacting the heart muscles, to regulate the beating of the heart...
.
In addition to synchronozied transcutaneous pacing offered by newer cardiac monitor/defibrillators there is also an option for Asynchronous Pacing. Sometimes in the prehospital setting a situation may arise where ECG electrodes are not available or something interferes with their adhesion to the patient's skin. In these rare situations where the patient must be paced and there are no other alternatives Asynchronous Pacing may be used. Again this setting should only be used as a last resort due to possible adverse cardiac effects it could cause.