What considerations should be taken when setting up a Lifepack (defibrillator) 15 for pacing in a patient with a history of heart failure or coronary artery disease and potential arrhythmias such as atrial fibrillation or ventricular tachycardia?

Lifepack 15 Pacing Setup Considerations

For transcutaneous pacing with the Lifepack 15, start with a rate of 60-80 bpm and output at 70-80 mA, then titrate to capture while monitoring for mechanical capture via pulse check and hemodynamic response.

Initial Rate Settings

• Set the pacing rate between 60-70 bpm as the starting point for most bradycardic emergencies, as this range optimizes cardiac output without reducing stroke volume in patients requiring ventricular pacing 1
• In patients with heart failure, a pacing rate of 60-70 bpm enhances cardiac output compared to lower rates (40 bpm), with statistical significance demonstrated at 70 bpm 1
• Avoid rates below 60 bpm in symptomatic bradycardia, as lower rates fail to maximize hemodynamic benefit 2
• Consider rates up to 80 bpm in patients with heart failure and reduced ejection fraction, as optimal ventricular rate control in this population targets <80 bpm at rest 3

Output (Current) Settings

• Begin with 70-80 mA output and increase in 5-10 mA increments until electrical and mechanical capture is achieved
• Confirm mechanical capture by palpating a pulse synchronous with the paced rhythm—electrical capture on the monitor without a pulse indicates failure to achieve effective pacing
• Once capture is established, increase output by 10% above threshold to maintain a safety margin
• Typical capture thresholds range from 50-100 mA for transcutaneous pacing, but can be higher in patients with chest wall edema, obesity, or COPD

Mode Selection Based on Underlying Rhythm

For Atrial Fibrillation with Bradycardia:

• Use demand (synchronous) mode, which functions as VVI pacing—the device paces the ventricle only when intrinsic ventricular activity falls below the set rate 4, 2
• The American College of Cardiology recommends VVI pacing for symptomatic bradyarrhythmias when there is no significant atrial hemodynamic contribution, as occurs in persistent atrial fibrillation 5, 2
• Atrial pacing is contraindicated in permanent or persistent atrial fibrillation, as there is no organized atrial activity to capture 2

For Sinus Bradycardia or Heart Block with Sinus Rhythm:

• Use demand mode to allow intrinsic ventricular activity to inhibit pacing when the patient's rate exceeds the programmed lower limit 4
• This prevents competition between paced and intrinsic beats, reducing the risk of R-on-T phenomenon

For Asystole or Absent Ventricular Activity:

• Fixed (asynchronous) mode may be used initially, but switch to demand mode once any intrinsic rhythm returns

Critical Monitoring Parameters

• Continuously monitor for both electrical capture (wide QRS complexes following pacing spikes) AND mechanical capture (palpable pulse, blood pressure, improved mentation)
• Assess hemodynamic response: blood pressure, mental status, skin perfusion, and urine output
• Monitor for loss of capture, which may occur with patient movement, lead displacement, or changes in thoracic impedance
• Watch for failure to sense intrinsic beats, which could result in inappropriate pacing during the patient's own rhythm

Special Considerations for Heart Failure Patients

• In patients with heart failure and reduced ejection fraction, maintain strict rate control with target <80 bpm at rest, as both excessively fast and slow ventricular rates worsen outcomes 3
• The American College of Cardiology emphasizes that patients with congestive heart failure require maximum atrial contribution when possible, but this is not achievable with transcutaneous pacing 5
• A J-shaped relationship exists between ventricular rate and clinical outcomes in heart failure patients with atrial fibrillation, with optimal rates around 65 bpm (range 60-80 bpm) 3

Special Considerations for Atrial Fibrillation

• Patients with atrial fibrillation and heart failure have worse prognosis and require careful rate management 6
• Uncontrolled ventricular rates in atrial fibrillation can cause tachycardia-induced cardiomyopathy, which is reversible with adequate rate control 3
• The American Heart Association recommends ventricular rate control targeting <80 bpm at rest and <110 bpm during moderate exercise to prevent tachycardiomyopathy 3

Common Pitfalls to Avoid

• Never assume electrical capture equals mechanical capture—always confirm with pulse palpation and blood pressure measurement
• Avoid setting rates too low (<60 bpm) in symptomatic patients, as this fails to optimize cardiac output 1
• Do not use excessively high rates (>80-90 bpm) in patients with coronary artery disease or heart failure, as this increases myocardial oxygen demand and can worsen ischemia or precipitate heart failure 5
• Transcutaneous pacing is painful in conscious patients—provide adequate analgesia and sedation when possible
• Remember that transcutaneous pacing is a temporizing measure; arrange for transvenous pacing or definitive treatment promptly

Patient Comfort Measures

• Provide analgesia and sedation as the clinical situation allows, as transcutaneous pacing causes significant discomfort in conscious patients
• Consider fentanyl or morphine for analgesia and midazolam for anxiolysis if hemodynamically stable
• Explain the procedure to conscious patients to reduce anxiety