Approximately 1/3 - 1/2 of ICD patients receive a shock within one year of placement
Generally described by patients as a powerful "kick to the chest"
Can be very distressing and a source of anxiety for patients
Generally described by patients as a powerful "kick to the chest"
Can be very distressing and a source of anxiety for patients
Inappropriate Shocks
Causes
Misclassification by device of SVT or AF as VT or VF
Electrical Noise
Fractured Lead
Can be diagnosed by interrogation of device after a reported shock
Causes
Misclassification by device of SVT or AF as VT or VF
Electrical Noise
Fractured Lead
Can be diagnosed by interrogation of device after a reported shock
Misclassification by device of SVT or AF as VT or VF
Electrical Noise
Fractured Lead
Phantom Shocks
The perception of a shock without a delivered shock
Generally described by patients as a mild electrical pain or pain around the<unk>  site
More common in patients who have never had an actual shock
Occurs in 9% of patients each year
The perception of a shock without a delivered shock
Generally described by patients as a mild electrical pain or pain around the<unk>  site
More common in patients who have never had an actual shock
Occurs in 9% of patients each year
Infection
Most commonly S. aureus or S. epidermidis
2% local wound infection; 1% sepsis/bacteremia
Hematoma
Typically occurs shortly after placement
Most commonly S. aureus or S. epidermidis
2% local wound infection; 1% sepsis/bacteremia
Typically occurs shortly after placement
Dislodgment
Perforation (most commonly at RV apex)
Infection can cause severe sepsis
Tricuspid regurgitation
Coiling (ie: Twiddler's Syndrome)  Twiddler Syndrome after large pocket and<unk>  wires coiled around the generator
Delivery of pacing stimulus without depolarization
Functional - refractory myocardium, desensitized local tissue around the lead
Medical - drugs, myocardial disease, electrolytes
Technical - insufficient device output, lead dislodgment, fracture, insulation defect, ventricular wall perforation
Battery of End of Life (EOL)
Functional - refractory myocardium, desensitized local tissue around the lead
Medical - drugs, myocardial disease, electrolytes
Technical - insufficient device output, lead dislodgment, fracture, insulation defect, ventricular wall perforation
Failure to deliver a stimulus to the heart
Oversensing - most common cause: retrograde P’s, T’s, skeletal muscle myopotentials,
Crosstalk - type of oversensing where the ventricular lead senses atrial pacing stimulus, and ventilator output inhibited
Oversensing - most common cause: retrograde P’s, T’s, skeletal muscle myopotentials,
Crosstalk - type of oversensing where the ventricular lead senses atrial pacing stimulus, and ventilator output inhibited
Normal function: a sensed myocardial depolarization greater than the programmed threshold causes inhibition of pacing
Failure to sense results in a paced beat on top of an intrinsic beat (as the device is "unaware" of the intrinsic beat")
Voltages of patient's intrinsic QRS complex is too low to be detected
New intrinsic arrhythmia (AF has a smaller depolarization than sinus beat), AMI, electrolyte abnormalities, lead separation, battery depletion
Voltages of patient's intrinsic QRS complex is too low to be detected
New intrinsic arrhythmia (AF has a smaller depolarization than sinus beat), AMI, electrolyte abnormalities, lead separation, battery depletion
Physiologic electrical activity (T waves, muscle potentials)
External electromagnetic interference
Signals generated by interaction of different portions of the pacing system
Potentially life-threatening as it can cause V-Fib or (paradoxically) bradycardia due to failure to capture
Also known as Endless Loop Tachycardia
Formation of a re-entrant circuit causing inappropriate tachycardia
Most commonly: paced ventricular beat ->  retrograde AV node conduction -> intrinsic P wave -> device reacts to intrinsic P wave by looking for intrinsic QRS, but since AV node is now refractory it delivers a paced beat at the programmed P-R interval (typically ~200-250ms), starting the process anew
Tachycardia does not exceed programmed upper limit rate on pacemaker
Most commonly: paced ventricular beat ->  retrograde AV node conduction -> intrinsic P wave -> device reacts to intrinsic P wave by looking for intrinsic QRS, but since AV node is now refractory it delivers a paced beat at the programmed P-R interval (typically ~200-250ms), starting the process anew
Implantable Cardioverter-Defibrillator complication
Acute arterial ischemia
Pacemaker complication
Acute coronary syndrome 
Left ventricular assist device complications
Cardiac ablation complications
Aortic endograft complications
Myocardial rupture