Study guide
13.3 Implanted Cardiac Devices, LVAD Emergencies & Electrical Storm
ABIM Critical Care Medicine Study Guide Exam
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1 Chapter 1: Exam Orientation: Format, Blueprint & Study Strategy
1.1 ABIM Critical Care Medicine Exam: Format, Blueprint & Study Strategy
2 Chapter 2: Acute Respiratory Failure & ARDS
2.1 ARDS Definition, Pathophysiology & Phenotypes 2.2 Lung-Protective Mechanical Ventilation 2.3 Refractory ARDS: Prone Positioning, Neuromuscular Blockade & VV-ECMO
3 Chapter 3: Obstructive Airways, Pulmonary Vascular & Pleural Emergencies
3.1 Severe Asthma & COPD Exacerbations in the ICU 3.2 Massive & Submassive Pulmonary Embolism 3.3 Pulmonary Hypertension & Right Ventricular Failure in the ICU 3.4 Massive Hemoptysis, Complex Pleural Effusions & Thoracic Drainage
4 Chapter 4: Airway, Parenchymal & Nonthrombotic Pulmonary Emergencies
4.1 Airway Management, Upper-Airway Obstruction & Artificial-Airway Complications 4.2 Diffuse Alveolar Hemorrhage, Interstitial Lung Disease, Pulmonary Vasculitis & Noncardiogenic Edema 4.3 Severe Community-Acquired & Viral Pneumonia 4.4 Nonthrombotic Embolism (Air, Fat, Amniotic Fluid, Tumor, Septic) & Acute Chest Syndrome
5 Chapter 5: Mechanical Ventilation Modes, Dyssynchrony & Liberation
5.1 Mechanical Ventilator Modes & Advanced Breath Delivery 5.2 Patient-Ventilator Dyssynchrony & Waveform Analysis 5.3 Ventilator Liberation, Spontaneous Breathing Trials & Post-Extubation Support
6 Chapter 6: Shock Syndromes & Hemodynamic Principles
6.1 Shock Classification, Cellular Pathophysiology & Biomarkers 6.2 Hemodynamic Monitoring: Arterial Lines, CVP & Pulmonary Artery Catheter 6.3 Dynamic Assessment of Fluid Responsiveness & Resuscitation Targets
7 Chapter 7: Vasoactive Therapies & Mechanical Circulatory Support
7.1 Vasopressors & Inotropes: Pharmacology & Clinical Titration 7.2 Temporary Mechanical Circulatory Support: IABP, Impella & TandemHeart 7.3 Venoarterial ECMO (VA-ECMO) & Differential Hypoxemia 7.4 Post-Cardiac Arrest Care, Targeted Temperature Management & Neuroprognostication
8 Chapter 8: Acute Kidney Injury & Renal Replacement Therapy
8.1 KDIGO AKI Classification, Etiologies & Diagnostic Evaluation 8.2 Continuous Renal Replacement Therapy (CRRT) vs Intermittent Hemodialysis 8.3 Indications & Timing for RRT in Critical Illness: AKIKI & STARRT-AKI
9 Chapter 9: Electrolyte, Acid-Base & Endocrine Emergencies
9.1 Severe Dysnatremias: Hyponatremia, Hypernatremia & Osmotic Demyelination 9.2 Potassium, Calcium, Magnesium & Phosphate Disorders 9.3 Complex & Mixed Acid-Base Disorders: Boston vs Copenhagen vs Stewart 9.4 Endocrine Crises: DKA, HHS, Thyroid Storm, Myxedema Coma & Adrenal Crisis
10 Chapter 10: Glycemic Control, Hyperammonemia, Pituitary & Adrenal Disorders
10.1 ICU Glycemic Control & Severe Hypoglycemia 10.2 Non-Hepatic Hyperammonemia & Metabolic Encephalopathy 10.3 Pituitary Emergencies, Adrenal Excess & Critical Illness-Related Corticosteroid Insufficiency
11 Chapter 11: Acute Coronary Syndromes & Cardiac Arrhythmias
11.1 Acute Coronary Syndromes & Mechanical Complications of Myocardial Infarction 11.2 Critical Tachyarrhythmias: Atrial Fibrillation with RVR, VT & VF 11.3 Critical Bradyarrhythmias, Conduction Blocks & Temporary Cardiac Pacing
12 Chapter 12: Acute Heart Failure, Valvular & Pericardial Emergencies
12.1 Acute Decompensated Heart Failure & Cardiogenic Pulmonary Edema 12.2 Acute Valvular Regurgitation & Prosthetic Valve Emergencies 12.3 Pericardial Tamponade & Acute Aortic Syndromes
13 Chapter 13: Myocardial Disease, Hypertensive & Cardiac Device Emergencies
13.1 Fulminant Myocarditis, Stress & Peripartum Cardiomyopathy, and Hypertrophic Cardiomyopathy 13.2 Hypertensive Emergencies & Ruptured Abdominal Aortic Aneurysm 13.3 Implanted Cardiac Devices, LVAD Emergencies & Electrical Storm
14 Chapter 14: Sepsis & Systemic Infectious Diseases
14.1 Sepsis-3 Definitions & Surviving Sepsis Campaign 2026 Guidelines 14.2 Refractory Septic Shock & Adjunctive Therapies 14.3 Multidrug-Resistant Pathogens & Antimicrobial Stewardship in the ICU
15 Chapter 15: ICU-Acquired & Severe Focal Infections
15.1 Hospital-Acquired & Ventilator-Associated Pneumonia 15.2 Central Line-Associated Bloodstream Infections & Catheter-Associated UTIs 15.3 Intra-Abdominal Sepsis, Necrotizing Soft Tissue Infections & CNS Infections
16 Chapter 16: Focal, Special-Host & Systemic Infections
16.1 CNS Infections Beyond Bacterial Meningitis: Encephalitis, Brain Abscess & Epidural Abscess 16.2 Infections in the Immunocompromised Host, Tropical & Bioterror Infections 16.3 Infective Endocarditis, Device Infections & Other Focal Cardiovascular Infections 16.4 Antimicrobial Pharmacokinetics, Allergy, Toxicity & Infection Prevention 16.5 Gastrointestinal & Hepatobiliary Infections: Fulminant C. difficile, Typhlitis, CMV Colitis & Abscesses
17 Chapter 17: Neurocritical Care & Coma
17.1 Coma, Altered Mental Status & Acute Delirium in the ICU 17.2 Status Epilepticus & Non-Convulsive Status Epilepticus 17.3 Acute Ischemic Stroke & Intracranial Hemorrhage
18 Chapter 18: Cerebrovascular Syndromes, Encephalopathy & Withdrawal States
18.1 Cerebral Venous Sinus Thrombosis, PRES & Reversible Cerebral Vasoconstriction Syndrome 18.2 Alcohol & Sedative Withdrawal, Wernicke Encephalopathy & Drug-Induced Encephalopathy
19 Chapter 19: Intracranial Hypertension & Neuromuscular Weakness
19.1 Intracranial Pressure Monitoring, Cerebral Perfusion & Tiered ICP Management 19.2 Acute Neuromuscular Respiratory Failure, ICU-Acquired Weakness & Brain Death Determination
20 Chapter 20: Traumatic Brain Injury, Spinal Cord Injury & Toxin-Mediated Paralysis
20.1 Traumatic Brain Injury Management & Paroxysmal Sympathetic Hyperactivity 20.2 Acute Spinal Cord Injury, Neurogenic Shock & Autonomic Dysreflexia 20.3 Toxin-Mediated Paralysis & Neuromuscular Crises: Botulism, Tetanus, Tick Paralysis & Myasthenic Crisis
21 Chapter 21: Gastrointestinal, Hepatic & Abdominal Emergencies
21.1 Acute Upper & Lower Gastrointestinal Bleeding in the ICU 21.2 Acute Liver Failure & Severe Acute Pancreatitis 21.3 Abdominal Compartment Syndrome & Acute Mesenteric Ischemia
22 Chapter 22: Luminal GI Emergencies & Complications of Cirrhosis
22.1 Esophageal, Gastric & Bowel Emergencies: Perforation, Obstruction, Ogilvie Syndrome & Colonic Ischemia 22.2 Complications of Cirrhosis: Alcohol-Associated Hepatitis, Hepatorenal Syndrome & Pulmonary Vascular Syndromes
23 Chapter 23: Trauma, Burns & Perioperative Critical Care
23.1 Polytrauma Resuscitation, Damage Control & Massive Transfusion 23.2 Severe Burn Injury, Inhalation Injury & Environmental Emergencies 23.3 Perioperative Critical Care for High-Risk Surgical Patients
24 Chapter 24: Thoracic Trauma, Environmental Injury & Obstetric Critical Care
24.1 Thoracic Trauma: Flail Chest, Pulmonary Contusion, Great Vessel & Tracheobronchial Injury 24.2 Environmental Injury: Drowning, Diving, Altitude, Heat, Cold, Electrical & Radiation 24.3 Obstetric & Genitourinary Emergencies and the Physiology of Pregnancy
25 Chapter 25: Transplantation, Donor Management & Post-Cardiac Surgery Care
25.1 Solid Organ Transplant Recipients & Deceased Donor Management 25.2 Post-Cardiac Surgery Critical Care: Bleeding, Tamponade, Low Output & Vasoplegia
26 Chapter 26: Hematologic Emergencies, Toxicology, Critical Ultrasound & ICU Liberation
26.1 Hematologic Emergencies in the ICU: HIT, DIC, TMA & Anticoagulant Reversal 26.2 Critical Care Toxicology, Toxidromes & Specific Antidotes 26.3 Critical Care Point-of-Care Ultrasound (POCUS) 26.4 ICU Liberation, Analgosedation, Goals of Care & Critical Care Ethics
27 Chapter 27: Transfusion Medicine, Hematologic & Oncologic Disorders
27.1 Transfusion Medicine: Products, Thresholds, Reactions & Apheresis 27.2 Red and White Cell Disorders, Hemoglobinopathies, Factor Deficiencies & Hypercoagulable States 27.3 Oncologic Emergencies, Hematopoietic Cell Transplant Complications & Cellular Therapy Toxicity
28 Chapter 28: Clinical Pharmacology, Adverse Drug Reactions & Specific Poisonings
28.1 Pharmacokinetic Principles, Dose Adjustment & Drug Interactions in Critical Illness 28.2 Adverse Drug Reactions: Anaphylaxis, Severe Cutaneous Reactions & Hyperthermic Syndromes 28.3 Specific Poisonings: Sodium-Channel Blockers, Lithium, Valproate, Theophylline, Iron, Sulfonylureas & Methemoglobinemia
29 Chapter 29: Ethics, Research Methods, Administration & Abdominal Ultrasound
29.1 Advance Care Planning, Nonbeneficial Treatment, Informed Consent & Confidentiality 29.2 Critical Care Research Methods, Statistics, IRB Oversight & Quality Improvement 29.3 Abdominal, Vascular & Procedural Point-of-Care Ultrasound
13.3 Implanted Cardiac Devices, LVAD Emergencies & Electrical Storm
Key Takeaways Explain This Topic AI
Placing a magnet over a pacemaker causes asynchronous pacing at a fixed rate; over an ICD it suspends tachytherapy but does not change the pacing mode.
Electrical storm is three or more separate episodes of ventricular tachycardia, ventricular fibrillation, or appropriate ICD shocks within 24 hours.
Preferred therapy for electrical storm is a nonselective beta-blocker (propranolol beat metoprolol in a randomized trial) plus amiodarone, with deep sedation for refractory cases.
A low-flow alarm with high power on an LVAD suggests pump thrombosis, whereas a suction event from hypovolemia or right ventricular failure produces low flow with low power and ventricular ectopy.
Chest compressions are given in LVAD cardiac arrest when there is no perfusion, despite the historical concern about cannula dislodgement.
Last updated: October 2026
- Pacemakers and Defibrillators in the ICU
- Reading the Device
A device interrogation answers four questions: the underlying rhythm, the programmed mode and rates, lead integrity and thresholds, and stored arrhythmia episodes with therapies delivered. Get it early in any patient with an implanted device and a rhythm or hemodynamic problem.
Malfunction Appearance Common causes
Failure to output No pacing spikes when expected Battery depletion, lead fracture, oversensing, generator failure, magnet-mode confusion
Failure to capture Pacing spike without a resulting complex Lead dislodgement, high threshold from fibrosis, hyperkalemia, acidosis, myocardial infarction, class I antiarrhythmics
Oversensing Inappropriate inhibition of pacing Myopotentials (shivering, diaphragmatic), electromagnetic interference, lead insulation failure, T-wave oversensing
Undersensing Pacing spikes in a competing rhythm Low-amplitude signals, lead problems, programming
Pacemaker-mediated tachycardia Endless loop reentry at the upper rate limit Retrograde atrial conduction in a dual-chamber device; magnet application terminates it
Twiddler syndrome Lead displacement from patient manipulation Coiled lead on radiograph
Hyperkalemia deserves special emphasis: it raises the capture threshold and can cause sudden loss of capture in a pacemaker-dependent patient.
Magnets
Over a pacemaker : asynchronous pacing at a fixed manufacturer-specific rate (commonly 85 to 100 bpm). Useful when oversensing is inhibiting pacing, or during electrocautery.
Over an ICD : suspends antitachycardia therapy (shocks and antitachycardia pacing) but does not change the pacing mode . This is the tool for repeated inappropriate shocks.
Inappropriate Shocks
Causes include atrial fibrillation with rapid conduction, sinus tachycardia above the detection rate, T-wave oversensing, lead fracture (look for high-frequency noise on the stored electrogram), and electromagnetic interference. Each shock is painful and proarrhythmic. Apply a magnet, treat the underlying rhythm, then arrange reprogramming.
Perioperative and ICU Considerations
Use bipolar electrocautery when possible, keep the return pad so current flows away from the device, and consider a magnet for a pacemaker-dependent patient.
MRI requires a conditional system and a specific protocol.
External defibrillation : place pads at least 8 cm from the generator, preferably anterior-posterior; interrogate the device afterward.
Cardioversion in a pacemaker-dependent patient can transiently raise thresholds; have transcutaneous pacing available.
CIED infection : any pocket infection or device-related bacteremia requires complete system extraction ; antibiotics alone fail. Obtain blood cultures and a transesophageal echocardiogram for lead vegetations.
Electrical Storm
Definition : three or more separate episodes of ventricular tachycardia, ventricular fibrillation, or appropriate ICD therapies within 24 hours.
Precipitants : acute ischemia, heart failure decompensation, electrolyte disturbance (potassium, magnesium), QT-prolonging drugs, thyrotoxicosis, high catecholamine states, and new or progressive scar.
Treatment sequence :
Beta-blockade , which is the cornerstone. A randomized comparison found propranolol plus amiodarone superior to metoprolol plus amiodarone for terminating storm, because nonselective blockade counters the catecholamine surge more completely.
Amiodarone loading (150 mg IV, then infusion). Lidocaine is preferred when ischemia is the driver; procainamide is an option in selected monomorphic ventricular tachycardia.
Correct reversibles : potassium to 4.0 to 4.5 mEq/L, magnesium, acidosis, and hypoxemia; revascularize ischemia.
Sedation , up to deep sedation with intubation, reduces sympathetic drive and is a legitimate therapy, not a last resort.
Reprogram the device : raise detection rates and favor antitachycardia pacing to reduce shocks; apply a magnet while planning.
Advanced options : stellate ganglion block or thoracic epidural, catheter ablation, mechanical circulatory support to allow mapping, and cardiac sympathetic denervation.
In polymorphic ventricular tachycardia with a long QT , give magnesium, stop offending drugs, correct potassium, and pace or use isoproterenol to raise the rate. In short-coupled or Brugada-pattern storm , quinidine and isoproterenol are the specific options, and amiodarone is less useful.
Warning
Escalating catecholamines (dopamine, epinephrine, dobutamine) in electrical storm often worsens the arrhythmia. If shock coexists, mechanical circulatory support is preferable to inotrope escalation.
LVAD Emergencies
Continuous-flow devices (HeartMate 3, older HVAD) unload the left ventricle into the aorta without pulsatility.
Assessment basics :
Blood pressure is mean arterial pressure measured by Doppler opening pressure or an arterial line; the target is usually a mean of 70 to 90 mmHg (hypertension reduces flow and raises stroke risk).
Pulse oximetry and noninvasive cuffs are often unreliable.
Learn the four parameters: flow, speed, power, and pulsatility index .
Always listen over the pump; a change or absence of the hum is critical.
Scenario Parameters Clues Action
Hypovolemia or suction event Low flow, low power , low pulsatility index, ventricular ectopy Bleeding, diuresis, vomiting Volume resuscitation; reduce pump speed
Pump thrombosis Low flow with high power Hemolysis (high LDH and plasma free hemoglobin, dark urine), heart failure Anticoagulation intensification, thrombolysis in selected cases, pump exchange
Right ventricular failure Low flow despite adequate volume Elevated jugular venous pressure, rising creatinine and bilirubin, low pulsatility Inotropes, inhaled pulmonary vasodilators, avoid excessive speed, consider RV support
- Hypertension Reduced flow High mean arterial pressure Afterload reduction
- Outflow graft obstruction or kink Low flow, variable power Imaging Surgical correction
Other recurring emergencies :
Gastrointestinal bleeding from arteriovenous malformations and acquired von Willebrand disease due to loss of pulsatility. Manage with endoscopy, holding anticoagulation temporarily, octreotide in refractory cases, and avoiding over-reversal that risks pump thrombosis.
Driveline infection : local care, cultures, prolonged antibiotics, surgical debridement; it can seed the bloodstream.
Stroke , both ischemic and hemorrhagic, is the main cause of disability.
Aortic insufficiency developing over time creates a circular flow loop and recurrent heart failure.
Arrhythmia : ventricular arrhythmias are often tolerated hemodynamically because the pump continues, but they still need treatment.
Cardiac arrest with an LVAD : confirm pump function (listen, check parameters, verify power connections and controller). Treat reversible causes, defibrillate and give drugs as usual, and perform chest compressions when there is no perfusion despite a working pump; current guidance accepts the small risk of cannula dislodgement over the certainty of death without circulation. Always contact the implanting center's team early.