Equipment
To obtain venous access, a central venous access kit, a temporary external transvenous pacing generator (single-chamber or dual-chamber), and a pacing lead are required, along with the following:
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Sterile gown, gloves, cap, and face shield
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Either a drape or towels for skin preparation
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Lidocaine
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Sterile gauze
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Syringes
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Scalpel
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Saline flush
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Catheter
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Dilator
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Needle
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Wire
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Suture
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Needle driver
Fluoroscopy, electrocardiography (ECG), or echocardiography is required to direct intracardiac lead placement. Fluoroscopy is the modality most commonly used for this purpose and is the best direct visual aid for placement of the pacing lead within the heart. If fluoroscopy is not available, ECG or echocardiography may be used instead. An external defibrillator should also be available during the procedure.
Pacing leads
The standard pacing leads are bipolar leads that are usually 3-6 French in diameter. (Multipolar leads with more electrodes are being studied. [5] ) Some catheters have an inflatable balloon between the electrodes (floating catheters; see the first and second images below); others are semirigid (semifloating catheters; see the third and fourth images below).
Floating catheter that follows circulation flow. It may be used when fluoroscopy is not available.
Semirigid catheter typically used when fluoroscopy is available for implantation.
Semifloating catheters respond better to manipulation, but floating catheters are more useful when fluoroscopy is not available for placement of the lead. A floating catheter follows the flow to reach the right ventricle (RV). When it reaches the RV, it is deflated to prevent it from entering the right pulmonary artery. Single-pass atrioventricular (AV) sequential pacing catheters have proximal electrodes for atrial pacing and distal electrodes for ventricular pacing.
In addition, preformed atrial J-shaped catheters provide more stability for atrial pacing. Pacing is also made possible by using the proximal port or the distal port of a pulmonary artery catheter to pass a J-shaped atrial pacing wire or a ventricular pacing wire, respectively. In most situations, single-chamber RV pacing is the preferred choice. Temporary pacing leads do not have an active fixation mechanism.
External generators
External generators come in either single-chamber or dual-chamber models (see the images below). A single-chamber generator can usually modify rate (up to 180 beats/min), output (up to 20 mA), and sensitivity. An external dual-chamber pacing generator has most of the features necessary for dual-chamber pacing, along with antitachycardia pacing features.
External single-chamber pacing unit that has 3 main features to control rate, current, and sensitivity.
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External single-chamber pacing unit that has 3 main features to control rate, current, and sensitivity.
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External pacemaker unit capable of complex dual-chamber pacing.
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Floating catheter that follows circulation flow. It may be used when fluoroscopy is not available.
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Tip of floating catheter that inflates with 1-1.5 mL of air.
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Semirigid catheter typically used when fluoroscopy is available for implantation.
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Tip of semirigid catheter.
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(A) Ventricular pacing during asystole. There is increase in pacing voltage that eventually captures heart. (B) Atrioventricular (AV) sequential pacing. On fourth beat, atrium was paced, and because intrinsic ventricular activity happened before AV pacing interval, the pacemaker sensed it appropriately and did not fire. On fifth beat, intrinsic atrial activity is appropriately sensed by pacemaker, and pacemaker therefore did not pace atrium. This schematic tracing shows appropriate dual-chamber pacemaker function. (C) Ventricular pacing. Fourth pacing spike is not followed by any ventricular activity and does not capture (ie, loss of capture). (D) AV sequential pacing with fourth beat demonstrating undersensing dysfunction. On fourth beat, intrinsic QRS exists that was not sensed by pacemaker, and therefore pacemaker fired (pacemaker spike within intrinsic QRS can be seen); this could not capture heart because of being in refractory period of cardiomyocytes. (E) AV sequential pacing with oversensing problem on third beat. Pacemaker did not pace ventricle because of inappropriate sensing of intrinsic ventricular activity, which actually does not exist. Pacemaker picking up muscular potentials can be one reason for oversensing.
