Inserting Temporary Pacemakers

Temporary cardiac pacing provides electrical stimulation to a heart that is compromised by disturbances in the conduction system resulting in hemodynamic instability. A temporary pacemaker to treat a bradydysrhythmia or tachydysryhthmia is used when the condition is temporary and when a permanent pacemaker is either not necessary or is not immediately available when required. External transcutaneous pacing is now available on most modern defibrillators.

• Temporary transvenous pacing involves two components, i.e. obtaining central venous access and intracardiac placement of the pacing wire.
• The preferred route of access for temporary transvenous pacing is the internal jugular vein followed by subclavian and femoral veins,¹ but all the major venous access sites (internal and external jugular, subclavian, brachial, femoral) have been used and each is associated with particular problems.²
• The right sided veins should be used when possible.¹
• The use of antibiotics and ultrasound probes should be considered for all wire insertions.¹

Complications of temporary pacing

• Temporary pacemakers must be checked by competent staff at least once daily for pacing thresholds, evidence of infections around venous access sites, integrity of connections, and battery status of the external generator.
• Underlying rhythm should also be assessed and recorded at these checks.
• Complications may relate to the venous access, mechanical effects of the lead within the heart, the electrical performance of the pacemaker lead, or infection or thromboembolism caused by the presence of a foreign body.
• Complications occur in 14–20% of patients and the majority present with a pericardial rub, ventricular arrhythmias produced during electrode positioning, or infection.
• Complications include local trauma, pneumothorax, arrhythmias and cardiac perforation.³

• Emergency/acute:
  • Acute myocardial infarction with:
    • Asystole
    • Symptomatic bradycardia (sinus bradycardia with hypotension and type I 2nd degree AV block with hypotension not responsive to atropine)
    • Bilateral bundle branch block (alternating BBB or RBBB with alternating LAHB/LPHB)
    • New or indeterminate age bifascicular block with first degree AV block
    • Mobitz type II second degree AV block
  • Bradycardia not associated with acute myocardial infarction:
    • Asystole
    • 2nd or 3rd degree AV block with haemodynamic compromise or syncope at rest
    • Ventricular tachyarrhythmias secondary to bradycardia
• Elective:
  • Support for procedures that may promote bradycardia
  • General anaesthesia with:
    • 2nd or 3rd degree AV block
    • Intermittent AV block
    • 1st degree AV block with bifascicular block
    • 1st degree AV block and LBBB
  • Cardiac surgery:
    • Aortic surgery
    • Tricuspid surgery
    • Ventricular septal defect closure
    • Ostium primum repair
  • Rarely considered for coronary angioplasty (usually to right coronary artery) but may be required for angioplasty-induced bradycardia⁴
• Overdrive suppression of tachyarrhythmias

• Preparation:
  • Ensure that a defibrillator and other resuscitation equipment are immediately accessible.
  • The procedure requires strict aseptic technique, using a mask, gown and gloves.
  • ECG monitoring is required but the ECG leads should be off the chest.
• Cannulate right subclavian, right internal jugular or right femoral vein using Seldinger technique of guidewire and dilators to place sheath of correct size to allow passage of pacing wire.
• Mould the tip of the electrode to give a 20-30° curve for correct positioning in the heart.
• Advance electrode under ultrasound or fluoroscopic guidance until it lies vertically in the right atrium with its tip pointing towards the free wall on the right side.
• Rotate wire between index finger and thumb such that it points towards the patient’s left side, advance wire steadily through the tricuspid valve and along the floor of the right ventricle to the apex.
• Common problems:
  • Wire does not cross the tricuspid valve: continue advancing wire into right atrium until it catches on the wall and forms a large loop. If it passes into the IVC or SVC, pull back and push forward again until it does catch. With large loop in place, rotate wire until its tip flips through into the ventricle.
  • A wire appears to be in correct position but will not capture ventricle at acceptable output: fluoroscopy shows electrode tip is directed upwards towards left shoulder and directed posteriorly rather than anteriorly.
  • Cannot obtain satisfactory pacing, withdraw wire into right atrium and repeat attempt to cross tricuspid valve.
  • Difficulty in positioning wire at apex of right ventricle: pass tip of wire into right ventricular outflow tract and gently withdraw while rotating between index finger and thumb. When tip is at a downwards angle, advance towards apex.

• Set to 70/min or 10/min above patient’s ventricular rate.
• Set a pulse of 3V (or follow manufacturer’s instructions); at this voltage should capture ventricle so that each pacing spike is followed by a QRS complex. Determine voltage threshold by gradually turning down voltage until capture is lost (usually 0.7-1.0V) and usually set pacemaker to deliver pulse of at least twice threshold.
• Check sensing by setting pacemaker rate at 10-20/min <spontaneous ventricular rate and check ECG and pulse generator for pacing inhibition.
• Normally set sensitivity to maximum.
• Common problems:
  • No spikes seen and no output: usually due to failure of battery or generator or loose connection. Otherwise, oversensing cured by reducing sensitivity or going to fixed rate pacing.
  • Spikes seen but no capture: often a loose connection but may be due to exit block causing a high threshold. Check position of pacing wire and consider repositioning.

• With pacing wire positioned correctly and pacing established, remove introducer sheath carefully.
• Suture the wire to the skin close to the point of insertion and cover with a dressing.
• Arrange a chest x-ray to confirm a satisfactory position of the wire and to exclude a pneumothorax.