Management of Constrictive Pericarditis - Patient Posted for Pericardiectomy

1. PATHOPHYSIOLOGY (Understanding the Hemodynamic Problem)

• Equalization of diastolic pressures across all four chambers (RVEDP = LVEDP = 15-25 mmHg)
• Enhanced ventricular interdependence - the fixed total cardiac volume means filling of one ventricle occurs at the expense of the other
• "Square root" sign / dip-and-plateau on ventricular pressure tracing (rapid early filling followed by abrupt halt)
• Prominent x and y descents on CVP/JVP tracing (prominent y descent - "M or W" waveform)
• Kussmaul's sign - paradoxical rise in JVP on inspiration (increased venous return cannot be accommodated by the stiff pericardium)
• Low fixed cardiac output - the heart compensates via tachycardia, not stroke volume expansion

2. PREOPERATIVE ASSESSMENT & OPTIMIZATION

Clinical Evaluation

• History: dyspnea, orthopnea, ascites, peripheral edema, weight loss, exercise intolerance (NYHA class - directly predicts operative mortality)
• Signs: raised JVP, Kussmaul's sign, pericardial knock (early S3-like sound), hepatomegaly, ascites, pleural effusion

Key Investigations

Optimizing the Patient Before Surgery

• Control HR: avoid drugs that cause tachycardia but also avoid bradycardia - HR ~80-100 is physiologically necessary to maintain CO
• Diuretics for volume status - careful not to over-diurese (preload-dependent)
• Treat underlying cause if still active (e.g., anti-tuberculous therapy for TB pericarditis; patient should continue therapy perioperatively)
• Correct coagulopathy (FFP if needed)
• Nutritional assessment - many have significant protein-calorie malnutrition from chronic illness

3. ANESTHETIC MANAGEMENT

Hemodynamic Goals (the "4 Musts")

Monitoring

• Standard ASA monitors (SpO2, ETCO2, ECG, NIBP)
• Arterial line (radial) - mandatory, pre-induction, continuous beat-to-beat BP
• Central venous catheter - CVP monitoring (elevated baseline expected), drug administration
• Pulmonary artery catheter - strongly considered; useful for diagnosing post-decortication hemodynamic changes; watch for equalization of pressures
• Transesophageal echocardiography (TEE) - highly recommended; confirms diagnosis intraoperatively, guides volume status, detects new wall motion abnormalities if coronary injury, assesses post-decortication ventricular function
• Temperature monitoring - CPB may be needed
• Urinary catheter - urine output monitoring throughout

Induction

• Vasodilation (drop in SVR)
• Negative chronotropy (drop in HR)
• Negative inotropy

• Ketamine (1-2 mg/kg IV) - maintains HR and SVR via sympathetic stimulation; drug of choice
• Alternatively, etomidate (0.3 mg/kg) - hemodynamically neutral; appropriate in patients with severe compromise
• Opioid (fentanyl 2-5 mcg/kg or sufentanil) - attenuates laryngoscopy response without significant hemodynamic compromise
• Muscle relaxant: rocuronium or vecuronium - avoid succinylcholine if no specific indication (fasciculations increase O2 demand)
• Avoid: propofol (vasodilation, myocardial depression), halogenated agents at high doses (decreases SVR), deep inhalational induction
• Intubate with a cuffed ETT; have vasopressors (phenylephrine, noradrenaline) and inotropes ready at induction

Maintenance

• Low-dose volatile agent (isoflurane, sevoflurane) combined with opioid/fentanyl infusion - balanced technique
• Titrate volatile agent carefully; keep MAC low to avoid SVR drop
• TIVA (propofol infusion + opioid) is an acceptable alternative but monitor closely for vasodilation
• Ventilate with lung-protective strategy: avoid high PEEP (increases RV afterload, further impairs venous return)
• Maintain normocapnia; avoid acidosis

Surgical Approach Considerations

• Median sternotomy is the most common approach (~80% of cases - Fuster's Heart, 15th Ed.)
• Left anterior thoracotomy (5th ICS) allows direct access to LV pericardium
• CPB standby is mandatory - ~40% of patients require bypass (Mayo Clinic series of 513 patients)
  • Used when significant cardiac manipulation is needed or dissection is difficult
  • Femoral cannulation preferred if bypass becomes necessary
• Pericardial resection sequence: LV pericardium is freed first - this prevents pulmonary edema from the right ventricle ejecting against a still-constricted left ventricle (Mulholland's Surgery, 7th Ed.)
• Phrenic nerves must be preserved - a 1-2 cm pedicled strip of pericardium is left undisturbed along each nerve

4. INTRAOPERATIVE HAZARDS

1. Myocardial Injury / Chamber Entry

• The pericardium may be densely adherent to the epicardium ("concrete chest")
• Risk of myocardial laceration, chamber rupture - requires immediate CPB and repair
• Raw myocardial surfaces activate fibrinolytic pathways and coagulation cascade

2. Consumptive Coagulopathy

• Pericardiectomy causes release of fibrinolytic activators from the raw myocardial surface
• Expect generalized oozing secondary to consumptive coagulopathy in addition to surgical bleeding
• Have FFP, cryoprecipitate, platelets, packed RBCs, and tranexamic acid available
• Consider antifibrinolytic therapy (tranexamic acid 10-15 mg/kg or epsilon-aminocaproic acid)

3. Arrhythmias

• Manipulation of the heart during pericardial stripping provokes AF, VT, VF
• Have defibrillator pads placed before draping
• Amiodarone infusion available; correct electrolytes (especially K+ and Mg2+)

4. Post-Decortication Low Output Syndrome

• Sudden release of constriction exposes chronically atrophied myocardium to sudden volume overload
• The myocardium - accustomed to low filling - may not cope with sudden preload increase
• Treat with inotropic support: dopamine, dobutamine, adrenaline (epinephrine) as needed
• Some patients require intra-aortic balloon pump (IABP) or other mechanical support

5. Hemodynamic Monitoring After Decortication

• Watch for persistent elevation of CVP despite pericardial removal - suggests incomplete resection
• PA catheter helps confirm equalization has resolved
• Dramatic swings in BP are common; have vasopressors and inotropes running

5. POSTOPERATIVE MANAGEMENT

ICU Care

• All patients go to cardiothoracic ICU postoperatively
• Mechanical ventilation initially with gradual weaning; pulmonary edema is common post-decortication
• Continue invasive monitoring (arterial line, CVP/PA catheter)
• Inotropic support (dobutamine/adrenaline) as needed for low cardiac output state
• Aggressive diuresis once hemodynamically stable - mobilize accumulated fluid

Specific Concerns

• Pulmonary edema - re-expansion of chronically compressed pulmonary vasculature; manage with PEEP, diuretics
• Bleeding - coagulopathy from fibrinolysis; correct coagulation factors; re-explore if significant hemorrhage
• Arrhythmias - AF is common; rate-control with amiodarone; anticoagulate if persistent
• Low cardiac output - myocardial stunning is expected; usually improves over days-weeks-months
• Renal function - monitor urine output carefully; AKI is a significant post-op risk
• Pain control - thoracotomy/sternotomy pain; epidural or IV PCA; NSAIDs should be used cautiously given GFR concerns

6. PROGNOSIS & EXPECTED OUTCOMES

• Overall perioperative mortality: 5-15% (experienced centers)
• 70% of operative mortality is from low cardiac output syndrome
• 5-year survival: ~84%; 99% of late survivors are NYHA Class I or II
• LV function returns to normal in 40% of patients
• Recovery may be delayed by weeks to months due to incomplete visceral pericardium resection or myocardial atrophy/fibrosis

• Radiation-induced constriction (concomitant myocardial injury)
• NYHA Class III-IV preoperatively
• Renal failure
• Advanced age
• Pulmonary hypertension
• Hyponatremia
• Low preoperative cardiac output

7. SUMMARY: ANESTHETIC GOALS AT A GLANCE

"Maintain HR, Maintain Preload, Maintain SVR, Avoid Myocardial Depression"

1. Pre-induction arterial line
2. Ketamine or etomidate for induction
3. Have vasopressors and inotropes ready at induction
4. TEE for continuous hemodynamic guidance
5. CPB team on standby
6. Antifibrinolytic therapy (tranexamic acid) given early
7. LV decortication before RV
8. Post-decortication inotropic support anticipated
9. ICU for post-op care with continued invasive monitoring

Anaesthetic Management of a Patient with a Permanent DDD Pacemaker

1. UNDERSTANDING THE DDD PACEMAKER

2. PREOPERATIVE ASSESSMENT

Step 1 - Identify the Device

• Obtain the patient's pacemaker identification card (model, manufacturer, date of implant)
• Review most recent device interrogation report (within 12 months for pacemakers)
• If not available, identify from chest X-ray - the radiopaque manufacturer code on the generator
• Contact the device manufacturer if needed for specifications

Step 2 - Assess Pacemaker Dependence

• Pacemaker-dependent = patient has NO intrinsic escape rhythm (complete heart block, severe SND) - loss of pacing = asystole/haemodynamic collapse
• Not pacemaker-dependent = patient has an underlying intrinsic rhythm adequate for haemodynamic stability
• Determine from device interrogation: underlying rhythm, percentage of paced beats, lowest intrinsic rate

Step 3 - Key Pre-op Information Checklist (Miller's Anesthesia, 10th Ed.)

Step 4 - Cardiology Consultation

• Consult the patient's electrophysiologist/cardiologist pre-operatively
• Arrange for device programmer and technician to be available on the day of surgery for reprogramming if needed
• Obtain a formal pre-op device check for any significant surgery

Step 5 - Standard Pre-op Workup

• ECG: identify intrinsic rhythm, pacemaker spikes, paced morphology (LBBB pattern for RV paced), current rate
• 12-lead ECG confirms pacing function (atrial and ventricular spikes)
• CXR: lead position, number of leads, generator location
• Electrolytes: hypo/hyperkalaemia alters pacing thresholds and sensing
• Assess underlying cardiac disease (indication for pacemaker)

3. THE CENTRAL INTRAOPERATIVE THREAT: ELECTROMAGNETIC INTERFERENCE (EMI)

Sources of EMI in the OR

What EMI Does to a DDD Pacemaker

1. Oversensing - the pacemaker "reads" cautery artifact as intrinsic cardiac activity → inhibits pacing output → asystole in a pacemaker-dependent patient (most dangerous)
2. Triggered pacing - in a DDD device, atrial oversensing of EMI can trigger rapid ventricular pacing (tracking at sensor upper rate)
3. Noise reversion mode - sustained EMI may trigger asynchronous pacing (safety feature)
4. Power-on reset - very strong EMI can reset device to a backup mode (often VOO or DOO at a fixed rate)
5. Lead/generator damage - if EMI source is within 15 cm of the generator
6. Rate-responsive sensor activation - piezoelectric sensors may accelerate pacing in response to OR vibrations or ultrasound

4. INTRAOPERATIVE MANAGEMENT STRATEGY

Decision: Magnet vs. Reprogramming

• Medtronic: paces asynchronously at 85 bpm (normal battery) or 65 bpm (elective replacement interval)
• Abbott/St. Jude: paces asynchronously at 100 bpm (normal) → 85 bpm (near EOL), gradual transition
• Boston Scientific: varies - confirm beforehand
• Important: magnet response may be programmed OFF in some devices - must verify pre-operatively

Surgical Diathermy Precautions

1. Use bipolar electrocautery wherever possible - no significant EMI risk
2. If monopolar is essential:
   • Use only short bursts (<1 second)
   • Keep cautery as far from the device as possible
   • Place the dispersive (return) pad so that current path does not cross the generator - e.g., apply to ipsilateral thigh for lower limb surgery, or contralateral shoulder for head/neck surgery (Braunwald's)
   • Use the lowest effective power setting
3. Consider harmonic (ultrasonic) scalpel as an alternative - does not generate EMI

Disable Rate-Responsive Mode (DDDR)

• Rate-responsive sensors respond to physical activity (piezoelectric vibration, minute ventilation, QT sensing)
• In the OR, vibration from surgical equipment, movement, and mechanical ventilation can activate the sensor and cause inappropriate tachycardia
• Always disable rate-responsive mode preoperatively in DDDR pacemakers (Braunwald's Heart Disease)

5. MONITORING

• Standard ASA monitoring (ECG, SpO2, NIBP, ETCO2)
• ECG monitoring: look for pacemaker spikes and confirm capture - note that pacemaker spikes may not be visible on all ECG systems; use a system that displays pacing artifact
• Peripheral pulse monitoring is mandatory - the ECG alone can be deceptive:
  • During cautery artifact, ECG trace is obscured, but pulsatility (SpO2 waveform, arterial line tracing) shows whether the heart is actually beating
  • Use pulse oximetry plethysmography or arterial line waveform as a continuous pulse check independent of ECG (Morgan & Mikhail, Miller's)
• Arterial line - strongly recommended for major surgery in pacemaker-dependent patients; gives beat-to-beat BP and confirms mechanical capture
• Temperature monitoring - hypothermia increases pacing threshold

6. ANAESTHETIC TECHNIQUE

General Principles

• No single anaesthetic agent is specifically contraindicated solely due to a pacemaker
• The underlying cardiac disease (reason for pacemaker) often drives agent selection more than the device itself
• Avoid bradycardia-inducing drugs in non-pacemaker-dependent patients (neostigmine, large opioid doses, suxamethonium fasciculation-related bradycardia in vagotonic patients)
• Maintain normal electrolytes - hypo/hyperkalaemia and acidosis alter pacing thresholds

Specific Considerations by Drug

Avoid in the Perioperative Period

• MRI (unless MRI-conditional device confirmed)
• Lithotripsy (ESWL) directed near the device
• External DC cardioversion without disabling the device (risk of device reset; if needed, place paddles as far from generator as possible)
• Direct pressure or radiation near the generator

7. POSITION-SPECIFIC CONSIDERATIONS

8. POSTOPERATIVE MANAGEMENT

When Device Interrogation is Required Before Discharge from Monitored Setting:

1. Device was reprogrammed preoperatively - must be re-programmed back
2. Patient underwent cardiothoracic surgery (high risk of power-on-reset)
3. Significant intraoperative arrhythmia occurred
4. Hypotension or metabolic derangements (acidosis, electrolyte shifts) that may have altered pacing/sensing thresholds
5. Patient received cardioversion, defibrillation, or therapeutic radiation
6. Device cannot be re-evaluated within 1 month postoperatively

Routine Postoperative Care

• Continuous cardiac monitoring in PACU - watch for pacing spikes and confirm capture
• Do not discharge from monitored setting until device function is confirmed
• Routine outpatient device check within 1 month for most patients
• Ensure all reprogrammed settings are restored (especially rate-responsive mode and upper rate limits)

9. EMERGENCY/URGENT SURGERY (No Pre-op Interrogation Possible)

1. Check patient's pacemaker ID card
2. Review chest X-ray - identify manufacturer from generator markings
3. Apply a magnet while monitoring - observe for abrupt heart rate change:
   • Rate change occurs → device is likely a pacemaker
   • No rate change → device is likely an ICD
4. Manufacturer-specific magnet rates:
   • Medtronic: 85 bpm
   • Biotronik: 90 bpm
   • Abbott/St. Jude: 98.6 or 100 bpm
   • Boston Scientific: 100 bpm
5. If device emits a tone with magnet → it is an ICD (not a pacemaker)
6. Always have transcutaneous pacing pads and defibrillator ready

10. SUMMARY CHECKLIST

• Identify device (model, manufacturer, indication, last interrogation)
• Assess pacemaker dependence
• Battery life >3 months
• Cardiology consultation + device check
• Plan for EMI (magnet vs. reprogramming)
• Disable DDDR rate-responsive mode
• Correct electrolytes

• Transcutaneous pacing pads placed (anterior-posterior) for pacemaker-dependent patients
• External defibrillator immediately available
• Bipolar cautery preferred; if monopolar used - short bursts, dispersive pad positioned away from generator
• Monitor peripheral pulse (SpO2/arterial line) independent of ECG
• Magnet immediately available

• Continuous monitoring until capture confirmed
• Reprogram device back to original settings
• Interrogate device if high-risk procedure, arrhythmias, or metabolic shifts occurred
• Outpatient device check within 1 month