CASE REPORT automatic implantable cardioverter-defibrillator
Emergency Department Management of Patients With Automatic Implantable Cardioverter-Defibrillators The case of a patient with idiopathic dilated cardiomyopathy and complex ventricular arrhythmias who underwent placement of an automatic implantable cardioverter-defibrillator (AICD) and experienced inappropriate shocks during atrial fibrillation is presented. On presentation to the emergency department, the patient had experienced approximately ten device discharges over six hours. ECG revealed atrial fibrillation with a rapid, wide complex ventricular response. Initial management consisted of IV verapamil for rate control followed by deactivation of the AICD. The patient was subsequently hospitalized for treatment of atrial fibrillation. Inappropriate device discharges, a frequently reported AICD-associated complication, are discussed. [Craig SA, Hudson AD: Emergency department management of patients with automatic implantable cardioverterdefibrillators. Ann Emerg Med April 1990;19:421-424.] INTRODUCTION Since the implantation of the first automatic implantable cardioverterdefibrillator (AICD) in 1980,1 automatic cardioversion-defibrillation by permanently implantable electroshock units has played an increasingly prominent role in the management of patients with refractory ventricular arrhythmias. More than 5,000 AICD units have been implanted in patients in the United States. Numerous studies report decreased mortality in patients treated with these devices compared with patients treated with longterm antiarrhythmic drugs or surgical ablation techniques. 2-5 Particularly relevant to the emergency physician are the substantial variety and frequency of AICD-associated complications that have been documented. One of the most c o m m o n complications is the "inappropriate pulse" (ie, an electrical discharge occurring during a relatively benign cardiac rhythm such as atrial fibrillation, sinus tachycardia, or nonsustained ventricular tachycardia). Inappropriate pulses have been observed in 10% to 40% of patients with AICDs and often occur repetitively in patients with recurrent supraventricular tachycardias.g,3,s, 6 The case of a patient with repetitive inappropriate AICD pulses is discussed, and some basic guidelines for the management of patients presenting to the emergency department with AICD-related complaints are given.
Sandra A Craig, MD* AID Hudson, MDt Charlotte, North Carolina From the Departments of Emergency Medicine* and Internal Medicine,t Charlotte Memorial Hospital and Medical Center, Charlotte, North Carolina. Received for publication August 31, 1989. Accepted for publication November 6, 1989. Address for reprints: Sandra A Craig, MD, Department of Emergency Medicine, Charlotte Memorial Hospital and Medical Center, PO Box 32861, Charlotte, North Carolina 28232.
CASE REPORT A 48-year-old woman with a history of dilated cardiomyopathy and recurrent ventricular arrhythmias presented to the ED several months after AICD implantation stating that her AICD had discharged approximately ten times during that morning. Each episode was followed by severe left anterior chest pain but was not preceded by palpitations, dizziness, or syncope. On arrival at the ED, the patient's vital signs were blood pressure of 98/73 m m Hg; pulse, 88; respirations, 12; and temperature, 37.0 C. Physical examination revealed an anxious woman. The lungs were clear to auscultation and percussion, and the neck was without jugular venous distention. Cardiac examination revealed an apical pulse rate of 130 to 140 that was somewhat irregular, point of maximal impulse nondisplaced, and without murmurs, gallops, rubs, or clicks. Abdominal examination was unremarkable except for the AICD generator noted in the left upper qua& rant. Distal pulses were intact.
19:4 April 1990
Annals of Emergency Medicine
421/119
AICDs Craig & Hudson
..
,/
". . . . . . . . . . . . . . . . . . .
A ~ ovL,
A
i [
A
A.
~,
~
~
. ~
A
,
/V I
\
V3
FIGURE 1. Patient~ initial ECG. Initial ECG (Figure 1) revealed a wide complex tachycardia, irregularly irregular, with a ventricular rate of 155. P waves were not discernible. These findings were considered consistent with atrial fibrillation with aberrant conduction attributable to the p a t i e n t ' s u n d e r l y i n g cardiomyopathy. The patient was initially treated with IV verapamil in an effort to maintain a ventricular response below the programmed trigger rate of 160 beats per minute. Her AICD then was placed in the inactive mode using a standard pacemaker magnet. She received no further shocks while in the ED and was subsequently hospitalized for monitoring and pharmacologic management of supraventricular tachyarrhythmias (Figure 2). DISCUSSION Patients who present to the ED with AICD-related complaints generally report single or multiple device discharges. The physical discomfort a s s o c i a t e d w i t h t h e s e discharges varies widely among patients; most describe feeling a moderate blow to the chest followed by m o m e n t a r y 120/422
discomfort. Patients who have suffered repetitive discharges within a brief period often exhibit marked anxiety reactions as well. The emergency physician should attempt to determine whether the AICD is identifying appropriate (ie, ventricular) arrhythmias and whether deactivation and hospitalization are indicated. The evaluation becomes relatively straightforward when an arrhythmia can be d o c u m e n t e d in the ED by ECG or real-time monitoring. If the initial ECG reveals atrial fibrillation, supraventricular tachycardia, or another nontarget rhythm, the patient most likely experienced an inappropriate AICD pulse. In such cases, the device should be deactivated and the patient admitted to a monitored bed for pharmacologic management with digoxin, calcium channel blockers, f3-blockers, or procainamide. Patients already on antiarrhythmic therapy may need dosage adjustments, and the emergency physician s h o u l d c h e c k s e r u m drug levels where appropriate. Patients who have documented episodes of complex ventricular arr h y t h m i a s while in the ED most likely received an appropriate shock. Then, the physician should search Annals of Emergency Medicine
for causes of increasing ventricular ectopy, i n c l u d i n g s u b t h e r a p e u t i c drug levels, hypoxemia, hypokalemia, hypomagnesemia, or myocardial infarction. These patients should be admitted to a monitored bed and treated w i t h appropriate antiarrhythmics while awaiting results of these studies. The AICD should be left in the active mode unless external defibrillation is quickly and reliably available. Patients who remain in normal sinus r h y t h m in the ED but report multiple o u t p a t i e n t AICD pulses should be admitted for continuous ECG monitoring. If such pulses are preceded by s y m p t o m s of h e m o d y n a m i c c o m p r o m i s e , the A I C D probably should remain in the active mode. The AICD should be inactivated in the a s y m p t o m a t i c patient where external defibrillation is immediately available to preserve the AICD battery. The most difficult scenario is the patient who presents in normal sinus r h y t h m after a single A I C D discharge. In these cases, the history may provide some clue as to the appropriateness of AICD function. A patient who reports a single AICD discharge preceded by syncope or 19:4 April 1990
./3.
l
aVR
V4
VI
/,
./
r
:I
.
aVL
aVF
near-syncope and followed by an immediate sense of well-being most likely experienced an appropriate shock. 7 Such a patient can be discharged from the ED after consultation with a cardiologist. A history of AICD discharge after exercise or emotional stress suggests inappropriate pulsing in response to sinus tachycardia. S These patients m a y b e n e f i t f r o m p - b l o c k a d e or reprogramming of the trigger rate on the AICD unit. Inappropriate pulsing also has been d o c u m e n t e d in a s s o c i a t i o n with shivering, certain upper-extremity movements, or diaphragmatic contractions due to sensing of skeletal myopotentials. 7 Therefore, the emergency physician should take a detailed history of the circumstances surrounding each discharge. Holter monitoring may be helpful if discharges occur w i t h sufficient frequency. It is interesting to note that inappropriate AICD pulses have very rarely been documented to result in m a l i g n a n t dysrhythmias.3, 7 Their main morbidity lies in unnecessary patient discomfort and early battery depletion. In some instances, the history and 19:4 April 1990
V2
'
V3
cardiogram will not provide an explanation for AICD discharge. The phys i c i a n s h o u l d c h e c k s e r u m potassium, magnesium, and drug levels and rule out myocardial infarction where appropriate. AICD malfunction is also a possibility in these cases. The battery should be checked for impending failure, and chest and abdominal films should be examined for evidence of lead fracture. 7 Further disposition should be made after review of these tests and consultation with the patient's cardiologist. The e m e r g e n c y p h y s i c i a n m a y elect to inactivate an AICD in a patient who undergoes high-energy external defibrillation, internal defibrillation, or emergency surgery because electromagnetic interference may cause inappropriate AICD discharge in these settings. These units also s h o u l d be i n a c t i v a t e d postmortem or in the setting of CPR because discharges could be conducted to bystanders who are in c o n t a c t w i t h the patient. These p a t i e n t s should not undergo magnetic resonance imaging scanning due to the possibility of permanent damage to device components. Deactivation of an AICD is accomplished by placing a standard 30 Annals of Emergency Medicine
V5
~
"~'"
"~J"
FIGURE 2. ECG showing supra-
ventricuMr tachyarrhythmias. Gauss pacemaker magnet over the right upper corner of the pulse generator located in the patient's left upper abdomen. Proper positioning will result in audible pulsed tones synchronized to the cardiac QRS. The magnet should be left in place for 30 seconds until the tone becomes continuous, indicating that the AICD is in the inactive mode. The magnet can then be removed. To reactivate the AICD, position the magnet over the pulse generator for 30 seconds until the continuous tone changes to synchronized pulsed tones. Absence of tones in the setting of good magnet position suggests AICD malfunction or impending battery depletion, and the emergency physician should relay this information to the consulting cardiologist. 8
SUMMARY The case of a p a t i e n t w i t h an AICD who presented to the ED after multiple inappropriate AICD discharges due to atrial fibrillation with a rapid, wide complex ventricular response is discussed. Although the AICD reliably senses malignant yen423/121
AICDs Craig & Hudson
t r i c u l a r a r r h y t h m i a s , c l i n i c a l experie n c e h a s s h o w n t h a t u p t o 4 0 % of pat i e n t s w i l l r e c e i v e p u l s e s d u r i n g ben i g n c a r d i a c r h y t h m s s u c h as s i n u s tachycardia or supraventricular tachycardia. W h e n a p a t i e n t w i t h a n A I C D pres e n t s a f t e r e x p e r i e n c i n g a d e v i c e discharge, the emergency physician should attempt to determine the c a u s e of t h e d i s c h a r g e . P a t i e n t s w h o experience isolated appropriate p u l s e s o f t e n do n o t r e q u i r e f u r t h e r e v a l u a t i o n or t r e a t m e n t . H o w e v e r , if i n a p p r o p r i a t e p u l s i n g is s u s p e c t e d or witnessed, patient morbidity may be improved and device longevity en-
122/424
h a n c e d b y d e a c t i v a t i o n of t h e A I C D w h i l e c o r r e c t i v e t h e r a p y is a c c o m plished.
REFERENCES 1. Mirowski M, Reid PR, Mower MM, et al: Termination of malignant ventricular arrhythmias with an implanted automatic defibrillator in human beings. N Engl J Med 1980;303:322-324. 2. Borbola J, Denes P, Ezri MD, et al: The automatic implantable cardioverter-defibrillator. Arch Intern Med 1988;148:70-76. 3. Echt DS, Armstrong K, Schmidt P, et al: Clinical experience, complications, and survival in 70 patients with the automatic implantable cardioverter/defibrillator. Circulation 1985; 71:289-296. 4. Fogoros RN, Fiedler SB, Elson JJ: The auto-
Annals of Emergency Medicine
matic implantable cardioverter-defibrillator in drug refractory ventricular tachyarrhythmias. Ann Intern Med 1987;107:635-646. 5. Kelly PA, Cannom DS, Garan H, et al: The automatic implantable cardioverter-defibrillator: Efficacy, complications, and survival in patients with malignant ventricular arrhythmias. [ Am Coll Carctiol 1988;11:1278-1286. 6. Gabry MD, Brodman R, Johnston D, et al: Automatic implantable cardioverter-defibrillatot: Patient survival, battery longevity and shock delivery analysis. J A m Coil Cardiol 1987;9:1349-1356. 7. Echt DS, Winkle RA: Management of patients with the automatic implantable cardioverter/defibrillator. Clin Prog 1985;3:4-16. 8. Physicians Manual for the CPI Automatic Implantable Cardioverter-Defibrillator. St Paul,
Minnesota, Cardiac Pacemakers, Inc, 1986.
19:4 April 1990
Emergency Department Management of Patients With Automatic Implantable Cardioverter-Defibrillators The case of a patient with idiopathic dilated cardiomyopathy and complex ventricular arrhythmias who underwent placement of an automatic implantable cardioverter-defibrillator (AICD) and experienced inappropriate shocks during atrial fibrillation is presented. On presentation to the emergency department, the patient had experienced approximately ten device discharges over six hours. ECG revealed atrial fibrillation with a rapid, wide complex ventricular response. Initial management consisted of IV verapamil for rate control followed by deactivation of the AICD. The patient was subsequently hospitalized for treatment of atrial fibrillation. Inappropriate device discharges, a frequently reported AICD-associated complication, are discussed. [Craig SA, Hudson AD: Emergency department management of patients with automatic implantable cardioverterdefibrillators. Ann Emerg Med April 1990;19:421-424.] INTRODUCTION Since the implantation of the first automatic implantable cardioverterdefibrillator (AICD) in 1980,1 automatic cardioversion-defibrillation by permanently implantable electroshock units has played an increasingly prominent role in the management of patients with refractory ventricular arrhythmias. More than 5,000 AICD units have been implanted in patients in the United States. Numerous studies report decreased mortality in patients treated with these devices compared with patients treated with longterm antiarrhythmic drugs or surgical ablation techniques. 2-5 Particularly relevant to the emergency physician are the substantial variety and frequency of AICD-associated complications that have been documented. One of the most c o m m o n complications is the "inappropriate pulse" (ie, an electrical discharge occurring during a relatively benign cardiac rhythm such as atrial fibrillation, sinus tachycardia, or nonsustained ventricular tachycardia). Inappropriate pulses have been observed in 10% to 40% of patients with AICDs and often occur repetitively in patients with recurrent supraventricular tachycardias.g,3,s, 6 The case of a patient with repetitive inappropriate AICD pulses is discussed, and some basic guidelines for the management of patients presenting to the emergency department with AICD-related complaints are given.
Sandra A Craig, MD* AID Hudson, MDt Charlotte, North Carolina From the Departments of Emergency Medicine* and Internal Medicine,t Charlotte Memorial Hospital and Medical Center, Charlotte, North Carolina. Received for publication August 31, 1989. Accepted for publication November 6, 1989. Address for reprints: Sandra A Craig, MD, Department of Emergency Medicine, Charlotte Memorial Hospital and Medical Center, PO Box 32861, Charlotte, North Carolina 28232.
CASE REPORT A 48-year-old woman with a history of dilated cardiomyopathy and recurrent ventricular arrhythmias presented to the ED several months after AICD implantation stating that her AICD had discharged approximately ten times during that morning. Each episode was followed by severe left anterior chest pain but was not preceded by palpitations, dizziness, or syncope. On arrival at the ED, the patient's vital signs were blood pressure of 98/73 m m Hg; pulse, 88; respirations, 12; and temperature, 37.0 C. Physical examination revealed an anxious woman. The lungs were clear to auscultation and percussion, and the neck was without jugular venous distention. Cardiac examination revealed an apical pulse rate of 130 to 140 that was somewhat irregular, point of maximal impulse nondisplaced, and without murmurs, gallops, rubs, or clicks. Abdominal examination was unremarkable except for the AICD generator noted in the left upper qua& rant. Distal pulses were intact.
19:4 April 1990
Annals of Emergency Medicine
421/119
AICDs Craig & Hudson
..
,/
". . . . . . . . . . . . . . . . . . .
A ~ ovL,
A
i [
A
A.
~,
~
~
. ~
A
,
/V I
\
V3
FIGURE 1. Patient~ initial ECG. Initial ECG (Figure 1) revealed a wide complex tachycardia, irregularly irregular, with a ventricular rate of 155. P waves were not discernible. These findings were considered consistent with atrial fibrillation with aberrant conduction attributable to the p a t i e n t ' s u n d e r l y i n g cardiomyopathy. The patient was initially treated with IV verapamil in an effort to maintain a ventricular response below the programmed trigger rate of 160 beats per minute. Her AICD then was placed in the inactive mode using a standard pacemaker magnet. She received no further shocks while in the ED and was subsequently hospitalized for monitoring and pharmacologic management of supraventricular tachyarrhythmias (Figure 2). DISCUSSION Patients who present to the ED with AICD-related complaints generally report single or multiple device discharges. The physical discomfort a s s o c i a t e d w i t h t h e s e discharges varies widely among patients; most describe feeling a moderate blow to the chest followed by m o m e n t a r y 120/422
discomfort. Patients who have suffered repetitive discharges within a brief period often exhibit marked anxiety reactions as well. The emergency physician should attempt to determine whether the AICD is identifying appropriate (ie, ventricular) arrhythmias and whether deactivation and hospitalization are indicated. The evaluation becomes relatively straightforward when an arrhythmia can be d o c u m e n t e d in the ED by ECG or real-time monitoring. If the initial ECG reveals atrial fibrillation, supraventricular tachycardia, or another nontarget rhythm, the patient most likely experienced an inappropriate AICD pulse. In such cases, the device should be deactivated and the patient admitted to a monitored bed for pharmacologic management with digoxin, calcium channel blockers, f3-blockers, or procainamide. Patients already on antiarrhythmic therapy may need dosage adjustments, and the emergency physician s h o u l d c h e c k s e r u m drug levels where appropriate. Patients who have documented episodes of complex ventricular arr h y t h m i a s while in the ED most likely received an appropriate shock. Then, the physician should search Annals of Emergency Medicine
for causes of increasing ventricular ectopy, i n c l u d i n g s u b t h e r a p e u t i c drug levels, hypoxemia, hypokalemia, hypomagnesemia, or myocardial infarction. These patients should be admitted to a monitored bed and treated w i t h appropriate antiarrhythmics while awaiting results of these studies. The AICD should be left in the active mode unless external defibrillation is quickly and reliably available. Patients who remain in normal sinus r h y t h m in the ED but report multiple o u t p a t i e n t AICD pulses should be admitted for continuous ECG monitoring. If such pulses are preceded by s y m p t o m s of h e m o d y n a m i c c o m p r o m i s e , the A I C D probably should remain in the active mode. The AICD should be inactivated in the a s y m p t o m a t i c patient where external defibrillation is immediately available to preserve the AICD battery. The most difficult scenario is the patient who presents in normal sinus r h y t h m after a single A I C D discharge. In these cases, the history may provide some clue as to the appropriateness of AICD function. A patient who reports a single AICD discharge preceded by syncope or 19:4 April 1990
./3.
l
aVR
V4
VI
/,
./
r
:I
.
aVL
aVF
near-syncope and followed by an immediate sense of well-being most likely experienced an appropriate shock. 7 Such a patient can be discharged from the ED after consultation with a cardiologist. A history of AICD discharge after exercise or emotional stress suggests inappropriate pulsing in response to sinus tachycardia. S These patients m a y b e n e f i t f r o m p - b l o c k a d e or reprogramming of the trigger rate on the AICD unit. Inappropriate pulsing also has been d o c u m e n t e d in a s s o c i a t i o n with shivering, certain upper-extremity movements, or diaphragmatic contractions due to sensing of skeletal myopotentials. 7 Therefore, the emergency physician should take a detailed history of the circumstances surrounding each discharge. Holter monitoring may be helpful if discharges occur w i t h sufficient frequency. It is interesting to note that inappropriate AICD pulses have very rarely been documented to result in m a l i g n a n t dysrhythmias.3, 7 Their main morbidity lies in unnecessary patient discomfort and early battery depletion. In some instances, the history and 19:4 April 1990
V2
'
V3
cardiogram will not provide an explanation for AICD discharge. The phys i c i a n s h o u l d c h e c k s e r u m potassium, magnesium, and drug levels and rule out myocardial infarction where appropriate. AICD malfunction is also a possibility in these cases. The battery should be checked for impending failure, and chest and abdominal films should be examined for evidence of lead fracture. 7 Further disposition should be made after review of these tests and consultation with the patient's cardiologist. The e m e r g e n c y p h y s i c i a n m a y elect to inactivate an AICD in a patient who undergoes high-energy external defibrillation, internal defibrillation, or emergency surgery because electromagnetic interference may cause inappropriate AICD discharge in these settings. These units also s h o u l d be i n a c t i v a t e d postmortem or in the setting of CPR because discharges could be conducted to bystanders who are in c o n t a c t w i t h the patient. These p a t i e n t s should not undergo magnetic resonance imaging scanning due to the possibility of permanent damage to device components. Deactivation of an AICD is accomplished by placing a standard 30 Annals of Emergency Medicine
V5
~
"~'"
"~J"
FIGURE 2. ECG showing supra-
ventricuMr tachyarrhythmias. Gauss pacemaker magnet over the right upper corner of the pulse generator located in the patient's left upper abdomen. Proper positioning will result in audible pulsed tones synchronized to the cardiac QRS. The magnet should be left in place for 30 seconds until the tone becomes continuous, indicating that the AICD is in the inactive mode. The magnet can then be removed. To reactivate the AICD, position the magnet over the pulse generator for 30 seconds until the continuous tone changes to synchronized pulsed tones. Absence of tones in the setting of good magnet position suggests AICD malfunction or impending battery depletion, and the emergency physician should relay this information to the consulting cardiologist. 8
SUMMARY The case of a p a t i e n t w i t h an AICD who presented to the ED after multiple inappropriate AICD discharges due to atrial fibrillation with a rapid, wide complex ventricular response is discussed. Although the AICD reliably senses malignant yen423/121
AICDs Craig & Hudson
t r i c u l a r a r r h y t h m i a s , c l i n i c a l experie n c e h a s s h o w n t h a t u p t o 4 0 % of pat i e n t s w i l l r e c e i v e p u l s e s d u r i n g ben i g n c a r d i a c r h y t h m s s u c h as s i n u s tachycardia or supraventricular tachycardia. W h e n a p a t i e n t w i t h a n A I C D pres e n t s a f t e r e x p e r i e n c i n g a d e v i c e discharge, the emergency physician should attempt to determine the c a u s e of t h e d i s c h a r g e . P a t i e n t s w h o experience isolated appropriate p u l s e s o f t e n do n o t r e q u i r e f u r t h e r e v a l u a t i o n or t r e a t m e n t . H o w e v e r , if i n a p p r o p r i a t e p u l s i n g is s u s p e c t e d or witnessed, patient morbidity may be improved and device longevity en-
122/424
h a n c e d b y d e a c t i v a t i o n of t h e A I C D w h i l e c o r r e c t i v e t h e r a p y is a c c o m plished.
REFERENCES 1. Mirowski M, Reid PR, Mower MM, et al: Termination of malignant ventricular arrhythmias with an implanted automatic defibrillator in human beings. N Engl J Med 1980;303:322-324. 2. Borbola J, Denes P, Ezri MD, et al: The automatic implantable cardioverter-defibrillator. Arch Intern Med 1988;148:70-76. 3. Echt DS, Armstrong K, Schmidt P, et al: Clinical experience, complications, and survival in 70 patients with the automatic implantable cardioverter/defibrillator. Circulation 1985; 71:289-296. 4. Fogoros RN, Fiedler SB, Elson JJ: The auto-
Annals of Emergency Medicine
matic implantable cardioverter-defibrillator in drug refractory ventricular tachyarrhythmias. Ann Intern Med 1987;107:635-646. 5. Kelly PA, Cannom DS, Garan H, et al: The automatic implantable cardioverter-defibrillator: Efficacy, complications, and survival in patients with malignant ventricular arrhythmias. [ Am Coll Carctiol 1988;11:1278-1286. 6. Gabry MD, Brodman R, Johnston D, et al: Automatic implantable cardioverter-defibrillatot: Patient survival, battery longevity and shock delivery analysis. J A m Coil Cardiol 1987;9:1349-1356. 7. Echt DS, Winkle RA: Management of patients with the automatic implantable cardioverter/defibrillator. Clin Prog 1985;3:4-16. 8. Physicians Manual for the CPI Automatic Implantable Cardioverter-Defibrillator. St Paul,
Minnesota, Cardiac Pacemakers, Inc, 1986.
19:4 April 1990
