Transcutaneous pacing is a temporary medical procedure that uses external electrical impulses to stimulate the heart. This non-invasive method delivers controlled pulses of electric current through the chest, encouraging the heart muscle to contract. It serves as a rapid intervention to regulate heart rate by applying electrodes to the skin. This technique differs from internal pacemakers by providing ongoing external electrical support.
Understanding Its Purpose
Transcutaneous pacing is performed when a person’s heart beats too slowly, a condition known as symptomatic bradycardia. This slow rate causes concerning symptoms like low blood pressure, altered mental status, chest discomfort, or signs of inadequate blood flow. The procedure is useful for certain heart blocks, such as Mobitz II second-degree AV block or third-degree AV block, where electrical signals are disrupted. It stabilizes the patient until a more lasting solution, like a permanent pacemaker, can be implemented. This temporary measure is also used when other treatments, such as medications, are ineffective or unavailable.
The Pacing Procedure
Initiating transcutaneous pacing involves placing large electrode pads on the patient’s chest. The anterior-posterior position is preferred, with one pad on the front (anterior) and the other on the back (posterior). This “sandwiches” the heart, minimizing electrical resistance. An anterior-lateral placement can also be used, with one pad on the upper right chest and the other on the lower left side.
After secure application, the pads connect to a monitor/defibrillator with pacing capabilities. The medical professional selects “Pace” mode and sets the desired heart rate, typically 60 to 80 beats per minute, adequate for maintaining blood flow. The current, measured in milliamperes (mA), is gradually increased until the heart responds. This continues until both electrical and mechanical capture are observed, ensuring effective pacing.
Verifying Successful Pacing
Confirming effective transcutaneous pacing involves assessing both electrical and mechanical responses. Electrical capture is observed on the electrocardiogram (ECG) as a wide QRS complex with a broad T-wave following each pacer spike. This indicates the electrical impulse successfully depolarizes the heart’s ventricles. Without proper electrical capture, pacing is ineffective in generating a heartbeat.
Mechanical capture refers to the heart’s physical response to electrical stimuli, meaning it contracts and produces a pulse. This is verified by palpating a pulse, such as at the femoral or radial artery, that matches the set pacing rate. It is important to confirm a palpable pulse and not solely rely on the ECG, as electrical activity does not always guarantee effective blood circulation. An improvement in the patient’s condition, like increased blood pressure or improved consciousness, further confirms successful mechanical capture.
Ongoing Patient Management
Once transcutaneous pacing is initiated, continuous monitoring of the patient’s heart rhythm and vital signs is important. The pacing output, measured in milliamperes, should be set slightly above the level where consistent electrical and mechanical capture was achieved, typically about 2 milliamperes above. This ensures reliable pacing and accounts for minor fluctuations. Patients may experience discomfort from muscle contractions caused by the electrical impulses.
To address discomfort, pain management strategies are employed, and analgesia may be prescribed to improve tolerance. The skin underneath the pacing pads should be periodically inspected, especially if pacing is prolonged, to check for irritation or burns. As transcutaneous pacing is temporary, preparations for definitive treatment, such as a transvenous pacemaker or addressing the underlying cause of the slow heart rate, are made concurrently.