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C HAPTER 2 8 / Pacemakers and Implantable Defibrillators 701
Frequent and thorough follow-up care can help detect potential
problems early, preventing devastating results. ICDs have become
sophisticated and complex, providing information on patient ac-
tivity, heart rate, frequency of arrhythmia, as well as ICD status.
ICDs have continued to improve, enhancing patient safety and
comfort. Remote monitoring of ICDs can assist with regular fol-
low-up, and many ICDs have warning beeps or tones to alert the
patient of a change with their ICD system.
Special Considerations
Sex and Racial Differences
ICD therapy is recommended in all patients with HF and LV ejec-
tion fraction of 35% or less. Previous studies have shown a disparity
in which patients receive costly cardiovascular technologies. Her-
nandez et al. 110 obtained data from the AHA, Get with the Guide-
lines Program between January 2005 and June 2007 using a 30% EF
as implanting criteria. They compared baseline characteristics of pa-
tients that received ICD therapy with the characteristics of patients
who did not receive ICD therapy. Review of the 13,034 patients el-
igible for ICD therapy resulted in the following findings: (1) the fre-
quency of ICD therapy was low with only 35.4% of qualified pa-
tients receiving an ICD, (2) women were approximately 40% less
likely than men to receive and ICD, and (3) black patients were ap-
proximately 30% less likely than white patients to receive an
ICD. 110
Awareness programs should address the recommendation for
ICD therapy and the need for eliminating sex and racial dispari-
ties. Programs such a Get with the Guidelines 111 and the National
■ Figure 28-44 ICD. Electrogram tracings showing artifact from 88
fractured lead. Panel (A) shows intracardiac signal from stored electro- ICD registry provide nonbiased information on patients receiv-
grams, artifact signals and irregular cycle length confirm fracture. Panel ing ICD implants helping to reduce these disparities.
(B) shows real-time recording while having patient move arm with de-
tections suspended to reproduce artifact. This recording was from an End of Life Issues
older epicardial patch lead system and abdominal implant. The patient Decision about the deactivation of ICDs will become more common
was admitted to hospital for placement of new ICD system. (Marker as the uses of ICDs are increasing. The primary concern for a termi-
annotation for Medtronic Jewel 7202: VS, ventricular sense; FS, fibril- nally ill patient is the ICD could cause an unnecessary distressing
lation sense; FD, fibrillation detection-charge initiated.)
death due to painful shocks. Deactivating an ICD by turning off the
VT and VF therapies will not create discomfort; it would prevent
treatment of a life-threatening ventricular arrhythmia. It is unknown
how often patients are approached about end of life issues, and there
patient should be instructed to call emergency medical services for are no set practice guidelines to address these issues. Discussions are
transport to the hospital if having multiple shocks. When electro- needed to establish ethical criteria for end-of-life care in terminally
grams are available, interrogation of ICD can confirm fractured ill or elderly patients with implanted devices. 112,113
lead artifact (Fig. 28-44). In an emergency situation, placing a
large ICD/pacemaker magnet over the ICD can deactivate the
ICD, as mentioned. Magnets do not inhibit the bradycardia ther-
apy that is programmed into the ICD. A chest radiograph may be CONCLUSION
able to provide information on lead fracture or insulation breaks
and can diagnose a dislodged lead. 57,72,93 Tremendous technological advances have been made in the ICD
Failure to deliver therapy is caused by failure to detect the ar- since first implanted in 1980. The ICD is no longer a simple shock
rhythmia. This failure could be caused by a sensitivity problem, box. With the introduction of dual-chamber ICDs, many new pro-
a change in VT rate, deactivation of the device, or system fail- grammable features are available. The ICD provides high-energy
ure. Inadvertent deactivation of the ICD is rare but potentially shocking capabilities for VF, ATP features for VT and fast VT, atrial
devastating. The device could be inadvertently deactivated with therapies for atrial arrhythmias, and CRT for HF patients. Detec-
use of a magnet, or during a programming session. Therefore, a tion enhancements have improved dramatically. Inappropriate
final interrogation with a printout should always be performed. shocks have decreased. ICDs provide diagnostic data to assist the
Some ICDs (Guidant-Boston Scientific) can be programmed to clinician in providing cardiac care to their patients. Diagnostic data
turn off after a magnet has been placed over the ICD for ap- such as activity levels, minimum and maximum heart rates, fluid
proximately 30 seconds. Rarely, exposure to a strong magnetic level trends, and heart rate variability trends have become standard.
field results in deactivation. Battery depletion and circuit failure The future of device therapy will continue to evolve. Presently
could be other causes of the ICD failing to deliver therapy. there are studies involving leadless ICDs. 114 A leadless system