ICD是救命符還是不定時炸彈？兩個急診case看ICD的好處、危害與處置

De Maria E, et al. Antitachycardia pacing programming in implantable cardioverter defibrillator: A systematic review. World J Cardiol 2017;9(5):429-436. PMID 28603590。 原文："Beyond ATP use, excellent clinical results were obtained with programming standardization following these principles: extended detection time in ventricular fibrillation (VF) zone; supraventricular discrimination criteria up to 200 bpm; first shock in VF zone at the maximum energy in order to reduce the risk of multiple shocks." "In order to avoid significant delays in the delivery of shock therapy (in case of ATP failure) algorithms of ATP sequences during or before capacitor charging were soon implemented in the VF zone for most manufacturers; this strategy has been subsequently clinically validated as safe and effective." "Even more important, it has also been demonstrated that shock therapy is associated with a higher risk of mortality compared to ATP sequences only." ↩︎ ↩︎ ↩︎

Al-Khatib SM, et al. 2017 AHA/ACC/HRS Guideline for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death. J Am Coll Cardiol 2018;72(14):e91-e220. PMID 29097296。 原文："The subcutaneous implantable cardioverter-defibrillator is incapable of bradycardia pacing, biventricular pacing, or antitachycardia pacing. Therefore, patients who need any of these types of pacing from an ICD should not be offered a subcutaneous implantable cardioverter-defibrillator." ↩︎

Drew BJ, et al. Prevention of torsade de pointes in hospital settings: a scientific statement from the American Heart Association and the American College of Cardiology Foundation. Circulation 2010;121(8):1047-60. PMID 20142454。 原文："Second, episodes of drug-induced TdP usually start with a short-long-short pattern of R-R cycles consisting of a short-coupled premature ventricular complex (PVC) followed by a compensatory pause and then another PVC that typically falls close to the peak of the T wave." "Data from congenital LQTS studies indicate that a QTc >500 ms is associated with a 2- to 3-fold higher risk for TdP." "A long preceding pause increases the amplitude of early afterdepolarizations, which makes them more likely to reach the threshold necessary to produce a PVC or ventricular couplet." "If episodes of TdP persist, it may be necessary to repeat infusions of magnesium sulfate 2 g." "Magnesium sulfate 2 g can be infused intravenously as a first-line agent to terminate TdP irrespective of the serum magnesium level." "In contrast, isoproterenol infusion or overdrive pacing can suppress TdP in these circumstances." "An increase in heart rate to prevent pauses that may trigger TdP may be attempted with temporary transvenous atrial or ventricular pacing at rates >70 beats per minute." "Repletion of potassium to supratherapeutic levels of 4.5 to 5 mmol/L may also be considered, although there is little evidence to support this practice (Class IIb, Level of Evidence: C)." "indications for QT-interval monitoring include the following: (1) Initiation of a drug known to cause TdP; (2) overdose from potentially proarrhythmic agents; (3) new-onset bradyarrhythmias; and (4) severe hypokalemia or hypomagnesemia." "The trigger for TdP is thought to be a PVC that results from an early afterdepolarization generated during the abnormally prolonged repolarization phase of the affected myocardium." "If these ECG harbingers of TdP are recognized, it then becomes possible to discontinue the culprit drug and manage concomitant provocative conditions (eg, hypokalemia, bradyarrhythmias) to reduce the occurrence of cardiac arrest." "Chronic administration of amiodarone markedly prolongs the QT interval, yet it is very rarely associated with TdP." "It has been postulated (although as yet unproven) that unlike high-risk drugs that selectively prolong repolarization in myocytes located in the mid myocardium (M cells), amiodarone uniformly delays repolarization in all layers of the myocardial wall." ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎

Tisdale JE, et al. Drug-Induced Arrhythmias: A Scientific Statement From the American Heart Association. Circulation 2020;142(15):e214-e233。 原文："Drug-induced TdP is rare in patients without risk factors, which include heart rate–corrected QT interval (QTc) >500 milliseconds or QTc lengthening ≥60 milliseconds from pretreatment value" ↩︎ ↩︎

LITFL — Ashman Phenomenon（Cadogan M, Buttner R）。 原文："Ashman phenomenon describes an aberrant ventricular conduction, usually of RBBB morphology, which follows a short R-R interval and preceding relatively prolonged R-R interval" "The refractory period of the His-Purkinje system is proportional to the RR interval of the preceding beat." "So, when two beats are separated by a long RR interval, the subsequent refractory period will be relatively long." ↩︎

ECG Weekly（Amal Mattu）— Rhythm Interpretation: Ashman phenomenon vs. nonsustained ventricular tachycardia（2023-09-18）。 原文："Typically follows a long-short cycle, and is especially likely to occur with a short-long-short cycle" "Fisch Criteria for diagnosing Ashman phenomenon: A relatively long cycle immediately ahead of the cycle terminated by the aberrant QRS complex RBBB from aberrancy with a normal orientation of the initial QRS vector: concealed propagation of aberration is possible, such that it is possible to have a series of wide QRS supraventricular beats Irregular coupling of aberrant QRS complexes Absence of a full compensatory pause, as full compensatory pauses favor a ventricular origin." "This is NOT ventricular tachycardia and antidysrhythmic medications and hospitalization is unnecessary" ↩︎ ↩︎

Wigginton JG, et al. Part 9: Adult Advanced Life Support: 2025 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation 2025;152(suppl 2):S538–S577. PMID 41122884。 原文："The risk for developing torsades increases when the corrected QT interval is greater than 500 milliseconds and accompanied by bradycardia." "Magnesium may be considered for treatment of adults with recurrences of polymorphic ventricular tachycardia associated with a long QT interval (torsades de pointes)." "In patients with bradycardia or pause-precipitated torsades, expert consultation is best sought for additional measures such as overdrive pacing or isoproterenol." "Routine use of magnesium is not recommended for the treatment of polymorphic VT in adults with a normal QT interval." ↩︎ ↩︎ ↩︎ ↩︎ ↩︎

Jentzer JC, et al. Multidisciplinary Critical Care Management of Electrical Storm: JACC State-of-the-Art Review. J Am Coll Cardiol 2023;81(22):2189-2206. PMID 37257955。 原文："Electrical storm (ES) reflects life-threatening cardiac electrical instability with 3 or more ventricular arrhythmia episodes within 24 hours." "Inappropriate ICD therapies can be for arrhythmias such as nonsustained VT or supraventricular tachycardia (e.g., atrial fibrillation with rapid ventricular rate), or due to artifactual signals such as T wave oversensing or lead noise (e.g., lead fracture)." "ICD shocks can further exacerbate ES by provoking pain and emotional distress (including anxiety, depression, phantom shocks, and post-traumatic stress disorder), which further stimulate sympathetic drive and increase the risk of subsequent VA episodes potentially leading to a vicious cycle of VA and recurrent ICD therapies." ↩︎ ↩︎ ↩︎ ↩︎

Bilanovic A, et al. Uncovering phantom shocks in cardiac patients with an implantable cardioverter defibrillator. Pacing Clin Electrophysiol 2013;36(6):673-83. PMID 23437816。 原文："Implantable cardioverter defibrillator recipients sometimes report "phantom shocks" (PSs), defined as a reported shock lacking objective evidence." ↩︎

Petley GW, et al. Leakage current from transvenous and subcutaneous implantable cardioverter defibrillators (ICDs): A risk to the rescuer? Resuscitation 2019;137:148-153. PMID 30794831。 原文："More recently, subcutaneous ICDs (S-ICD) have been developed, which utilise a higher energy and more superficial electrodes compared with transvenous ICDs (T-ICD), raising safety concerns further." "Surface voltages (median RMS) to which the rescuer is likely to be exposed are higher when performing chest compressions from the patient's left side compared with the right (127 V vs 67 V respectively, 95% CI of difference -34 V to -67 V, P < 0.0001)." "Twenty-five patients were recruited. Rescuer current from S-ICDs was significantly higher than those from T-ICDs (S-ICD: Median RMS 135 mA range 91 mA-164 mA, T-ICD: Median RMS 31 mA, range 9 mA-75 mA, P < 0.0001)." "Chest compressions should be performed from the opposite side to the ICD to reduce rescuer risk." ↩︎ ↩︎ ↩︎ ↩︎

ZOLL PD 1200 Operation Manual。 原文："Pulse Duration: 40 milliseconds" "Typical threshold currents are usually between 40 and 80 mA." "Avoid touching the gelled area of the electrode while pacing. A minor electrical shock hazard exists." ↩︎ ↩︎ ↩︎

UK Defence Medical Services, Clinical Guidelines for Operations — Transcutaneous pacing。 原文："This will typically be between 50-100mA in adults." ↩︎

Soar J, et al. European Resuscitation Council Guidelines 2025: Adult Advanced Life Support. Resuscitation 2025;215:110769。 原文："On sensing a shockable rhythm, an ICD will discharge approximately 40 J (approximately 80 J for subcutaneous devices)" "For biphasic waveforms (rectilinear biphasic or truncated exponential biphasic, but not pulsed biphasic), defibrillation shock energy levels for the first shock is at least 150 J." "Do not defibrillate during manual chest compressions (even when wearing clinical gloves), as that practice is not safe to the rescuer." "Implantable medical devices may be damaged during defibrillation if current is discharged through defibrillation pads placed directly over the device. Place the pad away from the device (at least 8 cm) or use an alternative pad position (antero-lateral, anteroposterior)." "If an ICD fails to terminate a shockable rhythm, conventional external shocks should be delivered, placing any defibrillation pad/paddle more than 8 cm from the defibrillator box" "Cardioverter and pacing function should always be re-evaluated following external defibrillation, both to check the device itself and to check pacing/defibrillation thresholds of the device leads." ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎

Heyer Y, et al. A Systematic Review of the Transthoracic Impedance during Cardiac Defibrillation. Sensors (Basel) 2022;22(7):2808. PMID 35408422。 原文："Excluding outliers and pediatric measurements, the mean TTI recordings ranged from 51 to 112 Ω with an average TTI of 76.7 Ω under normal distribution." ↩︎

Ideker RE, Zhou X, Knisley SB. Correlation among fibrillation, defibrillation, and cardiac pacing. Pacing Clin Electrophysiol 1995;18(3 Pt 2):512-25. PMID 7777416。 原文："An electrical stimulus must create an electric field of approximately 1 V/cm in the extracellular space to stimulate myocardium during diastole." "The defibrillation threshold in terms of current is typically thousands of times greater than the diastolic pacing threshold." "Pacing requires a potential gradient of approximately 1 V/cm only in a small liminal volume of tissue immediately adjacent to the electrode." "Defibrillation requires an electric field of approximately 6 V/cm throughout all or almost all of the ventricular myocardium. Since some portions of the ventricles can be more than 10 cm away from the defibrillation electrodes, a shock of several amps is required to create this field, a current thousands of times greater than the pacing threshold." ↩︎ ↩︎

Expert Group on Driving and Cardiovascular Disease. New Standards for Driving and Cardiovascular Diseases. European Commission, Brussels, 2013。 原文："Lubinski et al (75) reported data from the Polish registry of 2162 patients implanted for secondary prevention of sudden cardiac death." "The probability of arrhythmic episodes was 1.9% in the first month, 3.3% in the second month and 3.7% in the third month. In the three months thereafter the added probability remained below 2% per month." "Secondary prophylaxis is defined as implantation after resuscitated cardiac arrest, or after spontaneous arrhythmias with hemodynamic compromise, including, but not limited to syncope. Primary prophylaxis is implantation for all other reasons." "ICD implantation for secondary prevention｜driving must cease for 3 months｜permanent driving ban" "ICD implantation for primary prevention｜driving must cease for 2 weeks｜permanent driving ban" "the expert group advises a restriction from driving of three months after appropriate ICD therapy, for patients implanted for primary and for secondary prevention, especially if the patient experienced symptoms of impaired consciousness." ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎

Epstein AE, et al. Addendum to "Personal and public safety issues related to arrhythmias that may affect consciousness": public safety issues in patients with implantable defibrillators. A scientific statement from the AHA and the Heart Rhythm Society. Circulation 2007;115(9):1170-6. PMID 17287391。 原文："Patients receiving ICDs for primary prevention should be restricted from driving a private automobile for at least 1 week to allow for recovery from implantation of the defibrillator." ↩︎

Merchant FM, et al. Time Course of Subsequent Shocks After Initial Implantable Cardioverter-Defibrillator Discharge and Implications for Driving Restrictions. JAMA Cardiol 2016;1(2):181-8. PMID 27437889。 原文："Of 73 503 ICD recipients who underwent remote monitoring, 14 230 (19.4%) experienced at least 1 ICD shock and were included in this analysis" "The cumulative incidence of receiving a second shock was 14.5% (IQR, 13.9%-15.1%) at 1 month and 28.7% (IQR, 27.9%-29.5%) at 6 months." "For noncommercial drivers (ie, drivers of private automobiles), the 2007 guidelines from the American Heart Association–Heart Rhythm Society recommend driving restrictions for 6 months among recipients of secondary-prevention ICDs or among recipients of primary-prevention ICDs who subsequently receive an appropriate ICD shock." ↩︎ ↩︎ ↩︎

Baltazar RF. Basic and Bedside Electrocardiography. Lippincott Williams & Wilkins, 2009。 原文："Antiarrhythmic agents: In torsades de pointes, antiarrhythmic agents that prolong the QT interval such as Class IA and Class III agents are not only ineffective but may be fatal." ↩︎

Magnesium Sulfate in Water for Injection仿單（Hospira, Inc.；openFDA set id 22ca78b4-f5a3-4144-cf89-5f633acf1e6d）。 原文："Parenteral use in the presence of renal insufficiency may lead to magnesium intoxication." "Because magnesium is removed from the body solely by the kidneys, the drug should be used with caution in patients with renal impairment." "Clinical indications of a safe dosage regimen include the presence of the patellar reflex (knee jerk) and absence of respiratory depression (approximately 16 breaths or more/minute)." "An injectable calcium salt should be immediately available" ↩︎