Page 707 - Cardiac Nursing

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C HAPTER 2 8 / Pacemakers and Implantable Defibrillators 683
Potential Complications of Pacing their hands away from the pacemaker pocket and to avoid ma-
nipulating the pulse generator.
Pacemaker complications can be caused by implant-related prob- Pacemaker syndrome refers to a constellation of symptoms re-
lems or by malfunction of any part of the pacemaker system (e.g. sulting from inadequate timing of atrial–ventricular contraction.
lead problems or generator problems). The pacing lead must be in Symptoms include fatigue, jugular venous distention and pulsa-
firm contact with the pulse generator for the system to work cor- tions in the neck, weakness, dizziness or near-syncope, hypoten-
rectly. In a permanent pacing system, good contact between the lead sion, HF, and pounding in the chest. Symptoms may occur dur-
connector pin and the pulse generator at the connector block of the ing periods of VVI pacing because of loss of AV synchrony or
pulse generator is dependent on a setscrew being tightened ade- when retrograde conduction to the atria occurs, causing the atria
quately during implantation; a loose setscrew can create problems to contract against closed AV valves. Contraction of the atria at a
with pacemaker output or sensing. In addition, normal pacemaker time when the AV valves are closed can activate stretch receptors
function can appear to be abnormal because of idiosyncrasies of spe- in the atrial wall and pulmonary veins, resulting in a reflex va-
cific devices or unusual programming, resulting in what appears to sodilation that causes hypotension and dizziness. The loss of AV
be abnormal pacing rates or changes in the AV interval. synchrony causes loss of atrial contribution to ventricular filling
Early complications of temporary or permanent pacemaker in- and may be another cause of symptoms.
sertion are usually related to lead insertion and include pneu-
mothorax or hemothorax, lead perforation (subclavian vein or
myocardium), air embolus, and ventricular arrhythmias. Compli- IMPLANTABLE CARDIOVERTER
cations occurring later can include infection at the insertion site, DEFIBRILLATORS
endocarditis, hematoma formation, venous thrombosis, skin ero-
sion over a permanent pulse generator, lead dislodgment or frac- An implantable cardioverter defibrillator (ICD) is a battery powered
ture, Twiddler syndrome, symptoms from pacemaker syndrome, electrical impulse generator that continuously monitors the heart
and pacemaker failure. 23,48,49 rhythm and delivers either a life-saving shock or burst of rapid pac-
Pneumothorax can occur when the subclavian vein is used for ing to terminate a ventricular arrhythmia and restore normal
lead insertion because the apex of the lung is located very near the rhythm. ICDs have been proven to prolong survival in patients who
subclavian vein, and lung injury is a possibility when accessing the are receiving the device for treatment of ventricular arrhythmias, or
vein. Pneumothorax may become manifest immediately or as long receiving the ICD for primary prevention of sudden cardiac death.
as 48 hours after implantation. Clinical signs of pneumothorax can Two landmark studies the Multicenter Automatic Defibrillator Im-
include respiratory distress, absence of lung sounds on the affected plantation Trial (MADIT II) 50 and the Sudden Cardiac Death in
side, chest pain, hypotension, elevated neck veins, and hypoxia. HF Trial (SCD-HeFT) both demonstrated that patients with heart
51
Lead perforation may be asymptomatic or it can lead to cardiac disease and decreased LV function could benefit from an ICD. The
tamponade if there is rapid accumulation of blood in the peri- ICD provides safe and effective therapy for ventricular arrhythmias.
cardium secondary to perforation of the RV wall. If the pacing lead The number of ICD implants have increased exponentially since
perforates the septum and enters the LV, the ECG may show an first implanted in 1980. Technological advances have improved the
RBBB pattern rather than the usual LBBB pattern that results from function of the implantable defibrillator. Given the increasing num-
pacing the RV apex. Intercostal muscle or diaphragmatic stimulation bers of patients with ICDs the goal of the chapter is to provide an
by a perforated lead can cause hiccups or muscle twitching in the understanding of the function of an ICD, appropriate ICD therapy,
chest wall. The presence of a friction rub after implantation can in- potential complications, and appropriate follow-up management.
dicate pericarditis or pericardial effusion caused by lead perforation.
Ventricular arrhythmias, either PVCs or runs of VT, can result Development
from irritation of the ventricle by the pacing lead. PVCs that are
caused by pacing lead irritation have the same morphology as The implantable defibrillator was the brainstorm of Dr. Michel
paced beats because they originate from the same spot. Lead- Mirowski. In the late 1960s, Mirowski conceived the idea of an au-
induced arrhythmias most often occur within 24 to 48 hours of tomatic implantable defibrillator after a close friend died from re-
lead placement and usually resolve spontaneously. peated episodes of ventricular arrhythmias. The first experimental
Pacemaker system infection can involve just the pacemaker model was tested successfully in 1969, and after many years and
pocket or the entire generator and lead system and can occur early much refining, the ICD was first implanted in humans in 1980. 52
or late after implant. The use of prophylactic antibiotics and irri- The device was experimental until 1985 when it gained full U.S.
gation of the pacemaker pocket with antibiotics at the time of im- Food and Drug Administration approval. The first generation de-
plant can reduce the incidence of infection. Infections involving vices were large (weighing 250 g and occupying a volume of 145
the lead system can lead to endocarditis and usually require re- mL), requiring implantation in a subcutaneous abdominal pocket.
moval of the entire pacing system until the infection is resolved. The earliest ICD systems required a thoracotomy approach.
Because patients are discharged so soon after implantation, they Patch electrodes were sutured to the pericardium over the apex of
need to be taught to look for and report signs of infection: red- the heart, and either epicardial screw-in leads or an endocardial
ness, swelling, or weeping of fluid from the pacemaker pocket; lead was placed for rate sensing and pacing. The leads were then
erosion of the pacemaker; and fever that is not related to the flu tunneled to the pulse generator in the abdominal pocket. 53
or other identifiable illness. The first ICD was a nonprogrammable, shock-only device in-
Twiddler syndrome is manipulation of a permanent pulse gen- tended to treat VF. Once the device detected the arrhythmia and
erator within its pocket by the patient. This can lead to rotation was completely charged the ICD was committed to deliver a
of the pacemaker and twisting of the leads, which can result in shock. This first ICD was quickly modified to a second-generation
lead fracture or dislodgment. Patients should be cautioned to keep device that had cardioversion capabilities. 54,55 The current