🫀 Mirza's Cardiology Notes

Electrophysiology (EP) Emergencies

7 min read

bootcampcardiologyepeeps

Hypotension after EP Procedure

  • Hypotension after EP procedure: blood loss, tamponade, pneumothorax
  • Tests:
    • EKG
    • Echo
    • CXR
  • Fluids
  • Risk of pneumothorax reduced now with increased use of U/S guided vascular access
    • Cephalic access involves dissecting down to the cephalic vein and directly inserting the lead into the vein, thereby avoiding a percutaneous stick and theoretically eliminating the risk of pneumothorax.
  • If small PTX (< 1-2 cm in max diameter) → manage with 100% NRB mask, serial CXR and observation
    • Pulm consult can help manage

Intermittent Bradycardia

  • Intermittent bradycardia
  • Example: pacing spikes being delivered, but failing to capture (Intermittent Failure to Capture)
    • Causes:
      • acute lead dislodgement
      • lead fracture (unusual acutely though)
      • primary device failure (rare)
      • set screw issue - lead removed from header
    • Tests to order:
      • EKG
        • use of magnet demonstrates atrial pacing with capture, V-pacing w/o capture
          • 💡 Magnet puts into DOO mode
      • Device interrogation
        • demonstrates elevated threshold on both atrial and ventricular lead
      • CXR

Inappropriate Shock

  • Inappropriate shock
    • device thinks VTach, but its not.
    • Story: over time, lead bends and ultimately fractures
    • Management
      • Place a magnet 🧲 on device → disables tachycardia detection
    • The higher the Ohms, the more likely it is to be a fracture
      • Impedance of ~2,000 Ohms is usually a lead fracture. In the case Dr. Gupta presented, device interrogation revealed a pacing impedance of 1800 ohms, previously at 900 ohms since implant. In that case, the device was turned off and RV lead revision performed the following day.
  • If you put a magnet 🧲 on a pacemaker it disables sensing
    • On call use → perform surgery involving electrocautery in pacemaker patients (tape it on for surg, remove it after)
    • If pt is pacemaker dependent, i.e. 100% dependent, you will need to call in the rep
  • If you put magnet on defibrillator, it disables tachycardia detection
    • On call use → perform surgery involving electrocautery (tape it on for surg, remove it after)
  • Magnet 🧲 effect
    • Pacemaker
      • Disables sensing
      • Switches to DOO or VOO mode
      • Used to perform surgery involving electrocautery in pacemaker dependent patients
    • Defibrillator
      • Disables tachycardia detection
      • Used to disable inappropriate shocks in patient with lead fracture or Afib with RVR
      • Used to perform surgery involving electrocautery

Wound

  • Wound
    • arrange for admission and extraction (device endocarditis can lead to valvular endocarditis)
    • If an incision is opened to the point where a device is visible, it must be assumed that there is bacterial spread to the device pocket and potential bacteremia since the leads are endovascular, the only possible option is to remove the device.
    • Risk factors for device infection include:
      • ESRD
      • prior transvenous temporary pacemaker insertion
      • a prior history of bacteremia or device infection
      • implantation of a larger device and need for re-operation within a 2 week period (highest risk)
    • High risk patients can get antibiotic pouches (2/3 reduction in device infection, but expensive so limit to high risk of infection patients)

Shoulder pain

  • Shoulder pain/issue (despite arm restrictions)

    • Solution: program an alternate pacing vector
      • If this fails, a pacing threshold of 1.2 at 0.5 msec could be programmed but it is very close to either losing capture or pacing the diaphragm.
    • The most likely cause of this is a closer approximation of the coronary sinus lead to the phrenic nerve when lying on the left side. Since implant procedures are performed supine, this position cannot be replicated during initial testing.
    • Most leads these days are quadrapole, so you will want to program around triggering some of the nerves

  • Left bundle pacing > His bundle pacing

  • Coronary sinus dissection → Cardiac tamponade

    • Mgmt
      • Echo, Fluids, Notify cath lab
    • Most CS dissections are benign
    • more common scenario leading to tamponade in EP procedure is with RV lead → RV apex

  • AF catheter ablation

    • most feared complication is atrio-esophageal perforation
      • get CT scan with IV contrast
      • Avoid putting anything down the esophagus
      • Dr. G showed pic with black dot in atria, which is the air from the perf

  • Nice summary slide with complications after common EP procedures

    • Grab these slides!

  • For device cases, a device check and a CXR is always a good idea

  • For ablation cases, an echo is always a good idea

Common EP Issues

  • Why is this pacemaker not working?
    • Programmable parameters
      • Lower pacing limit:
        • Nominal settings typically 50-60 bpm
      • Upper pacing limit:
        • Normal settings typically 120-130 bpm
  • Why is this ICD not working?
    • Programmable parameters
      • VT zones
        • 2-3 zones that can either define a monitor zone or a therapy zone
      • VF zones
  • Tachy/brady syndrome
    • Period of fast heart rates followed by slow rates
    • Treatment
      • Pacemaker placement only definitive treatment
      • Ablation of the tachyarrhythmias
      • Alternative medications, e.g. antiarrhythmics to ↓ tachycardia burden
  • AFib Screening
    • Pt w/ cryptogenic stroke
      • Start with 30 day monitor followed by consideration for implantable loop recorder if nothing found with 30 day monitor
    • Wearables, e.g. Apple watch, Kardia device
  • Supraventricular Tachycardia (SVT)
    • Types
      • Atrial tachycardia
        • typically start with BB (can also use flecainide in appropriate pts) for suppression
        • Ectopic focus found within the atrial tissue that causes a rapid heartbeat
          • Most common in patients with history of heart disease
      • Atrial flutter
        • Typical (more common) versus atypical (typically in LA, MV; need mapping to determine location)
          • typical flutter: negative P waves in inferior, + in V1
            • helpful to know b/c can go after the cavotricuspid isthmus
      • AVNRT (Atrioventricular nodal re-entrant tachycardia)
        • bimodal age distribution
        • pseudo-R’ in V1 (this is actually a P wave); compare to pts prior ECG when in sinus rhythm
      • AVRT (Atrioventricular reciprocating tachycardia)
        • Reciprocating tachycardia via an accessory pathway
      • Inappropriate sinus tachycardia
        • typically have sinus tachy even at rest
        • Nice protocol in Ahmed et al 2022 JACC paper
      • Multifocal atrial tachycardia
        • often mislabeled as AFib; don’t need AC w/ MFAT
        • tachycardia + ≥ 3 different P wave morphologies
  • PVCs
    • When do I worry?

      • 15% burden increases risk for cardiomyopathy

      • Heart failure signs or symptoms
      • Severe symptoms (may represent inherited channelopathies)
        • Palpitations worsened with exercise
        • Syncope
        • Malignant family history
    • Workup
      • Holter Monitor
        • To determine burden
        • Note: VE’s=ventricular ectopy
      • Exercise Stress Testing
      • Ischemic workup if comorbids/RFs
    • Treatment
      • Lifestyle modifications
      • Beta-blockers or calcium channel blockers
      • Antiarrhythmic therapy (if high burden)
        • Can help determine: “Is the CM driving PVCs? or are PVCs the cause of the cardiomyopathy?”
      • Ablation

Decoding Pacemaker Codes

  • Which chamber is paced? whgich sense? response to sensing? rate adaptive?
    • DDD
    • DDDR
    • VVI
      • only ventricular chamber that is paced, sense and response
    • VVIR
    • DOO or VOO
    • MVP
      • specific mode of Medtronic to promote intrinsic induction
      • useful in SSS where we only want to pace in the upper chambers
    • AAI
  • Mode switch
    • Prevents tracking of an atrial tachyarrhythmia to prevent rapid ventricular paced rhythm

ICD Parameters

  • Rate
  • Morphology
  • Pattern
    • Evaluates the atrial to ventricular pattern, i.e. 2:1 AV or near simultaneous A and v
  • AV dissociation
    • i.e. no atrial intervals within a ventricular interval or varying AV interval by >40 msec

Overdrive Pacing

⚠️ The following is what I wrote down for working with an Abbott/St. Jude’s device to overdrive pace a patient with VT, so take with a grain of 🧂 for other manufacturers.

  1. Grab the appropriate machine from the closet near Cath Lab 3
  2. Power on the machine (button located on the Left side for the St. Jude machine)
  3. Place the wand 🪄 on the patient’s chest near their device
  4. On the right-side of the screen, select Tests
  5. Click the Fibber & NIPS tab
    1. NIPS stands for non-invasive programmed (ventricular) stimulation
  6. Click Ventricular NIPS
    1. If you need to measure the cycle length, you can click the camera 📸 at the right or Automatically identify the cycle length
  7. For example, the patient we saw was at 500 ms. We want to overdrive and go faster, so we could try a cycle length of 450 ms, etc.
  8. Push the green button 🟢 to burst for 10-15 seconds (FYI, it will time out at 20 seconds)
  9. 🔁 If unsuccessful, continue to try lower cycle lengths, e.g. ↓ by 10-30 ms and try again.
    1. In our patient’s case, we ultimately needed to go down to 380 ms for him to snap out of it.

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