Lecture on Pacemaker Timing Cycles

Introduction

• Speaker: AJ Hale, Certified Cardiac Device Specialist
• Topic: Pacemaker Timing Cycles
• Format: Interactive with real-life examples and EGM (Electrocardiogram) analysis
• Engagement: Questions encouraged via chat or Q&A

Key Concepts

Pacemaker Timing Cycles

• Max Track Rate: Maximum rate at which the device tracks atrial activity
• Pacemaker WinkyBock: Behavior when atrial rate exceeds max track rate
  • Extended AV delay until atrial event falls into refractory period
  • One-to-one atrial synchrony resumes below max track rate

Atrial and Ventricular Channels

• Atrial Channel Observations: Ventricular activity, bivy pacing
• Loss of Capture: Indicated by no evoked response
  • Solutions include increasing outputs, conducting a chest x-ray

Timing Cycles Detailed

Atrial Timing Cycles

• Paced AV Delay: Time for diastolic filling and intrinsic conduction
• Sensed AV Delay: Generally shorter than paced AV delay
• PVARP (Post Ventricular Atrial Refractory Period)
  • Prevents pacemaker-mediated tachycardia (PMT)
  • PMT typically involves retrograde conduction
• PVAB (Post Ventricular Atrial Blanking)
  • Avoids far-field R waves
  • Blanking period where device is "blind"

Ventricular Timing Cycles

• Ventricular Blanking: Prevents crosstalk
  • Crosstalk can inhibit ventricular pacing
• Ventricular Refractory Period (VREF)
  • Avoids double-counting T waves

Scenarios and Examples

Scenario Analysis

• Scenario 1: Sinus Bradycardia with ventricular pacing
  • Issue: Far-field oversensing and mode switch
  • Solution: Lengthening PVAB
• Scenario 2: Dual chamber ICD analysis
  • Issue: Far R wave oversensing and retrograde conduction
  • Solutions: Extend PVAB, adjust sensitivity
• Scenario 3: Non-sustained RV oversensing
  • Complex example with VSP and APACE on PVC
  • Solution: Turn off APACE on PVC

Technical Aspects and Device Management

Programming Considerations

• Unipolar vs. Bipolar: Differences in impedance and sensing
• Sensitivity Adjustments: Impact on sensing intrinsic activity
  • Algorithms to adjust sensitivity dynamically
• Lead Impedance: Indicators of conductor failure or insulation breach

Quiz Recap

• IS4 and DF4 Leads: Compatibility details
• Pacing Outputs: Amplitude and pulse width
• Sensitivity: Raising threshold vs. sensitivity
• Lead Malfunctions: Recognizing issues through impedance patterns

Closing

• Summary: Emphasis on understanding device inputs and programming
• Q&A and Support: Encouragement to reach out for further discussions

The lecture covered a comprehensive approach on understanding pacemaker timing cycles, troubleshooting common issues, and programming considerations for optimal device performance.