896

PEDIATRIC CARDIOLOGY

The Automatic Implantable Cardioverter-Defibrillator inYoung Patients

JACK KRON, MD, FACC, RONALD P. OLIVER, BS, STEPHAN NORSTED, PHD,*

MICHAEL J. SILKA, MD, FACC

Portland, Oregon

JACC Vol. 16. No.4October 1990:896-902

An international survey identified 40 patients <20 years oldwho underwent surgical implantation of an automatic im­plantable cardioverter-defibrillator (AICD). There was ahistory of aborted sudden cardiac death or sustained ven­tricular tachycardia in 92.5% of these patients. Twenty-twopatients (55%) had structural heart disease; dilated andhypertrophic cardiomyopathy were the most common diag­noses. Eighteen patients (45 %) had primary electricalabnormalities including seven with the congenital long QTsyndrome. There were no perioperative deaths associatedwith device implantation. Concomitant drug therapy wasadministered to 75% of the patients.

Since the first automatic implantable cardioverter­defibrillator (AICD) was implanted in 1980 (1). defibrillatortherapy has become an important treatment approach forpatients who survive sudden cardiac death (2-8). with ap­proximately 11.000 units implanted worldwide (Smutka M.personal communication). Most of these implantations havebeen in adults. with coronary artery disease (8) the predom­inant underlying diagnosis.

Sudden cardiac death due to tachyarrhythmias has be­come an increasingly recognized cause of death in youngpatients (9-16). Because of the heterogeneity of underlyingcardiac diagnoses in these patients. a variety of therapeuticstrategies may be required (16). The application of the AlCDto the young sudden cardiac death survivor represents onelogical therapeutic approach. However. there are few pub­lished data that address the extension of defibrillator therapyto the young patient (17). Therefore. this study was under­taken to further characterize young patients who have

From the Division of Cardiology. Departments of Medicine and Pediat­rics. the Oregon Health Sciences University. Portland. Oregon and 'CardiacPacemakers. Inc .. St. Paul, Minnesota.

Manuscript received January 10. 1990: revised manuscript receivedMarch 21. 1990. accepted April 13. 1990.

Address for reprints: Jack Kron. MD. Division of Cardiology. L-462.Oregon Health Sciences University. 3181 Southwest Sam Jackson Park Road.Portland. Oregon 97201-3098.

IQ 1990 by the American College of Cardiology

Defibrillator discharge occurred in 70% of the patients,with 17 patients (42.5 %) receiving at least one appropriateshock. There were two sudden and two nonsudden deathsat 28.2 months' median follow-up. Sudden death-freesurvival rates by life table analysis at 12 and 33 monthswere 0.94 and 0.88, respectively. Total survival rates at12 and 33 months were 0.94 and 0.82, respectively. TheAICD represents an effective treatment approach foryoung patients with life-threatening ventricular tachyar­rhythmias.

(J Am Coli CardioI1990;16:896-902)

received an AICD and to examine surgical considerationsand outcome in these patients.

MethodsStudy patients. To identify the population of patients who

were <20 years old at the time of AICD implantation theCardiac Pacemakers data base was utilized. Subjects werenoted and referred to only by registration number to protectconfidentiality. Implanting or attending physicians were con­tacted directly or by questionnaire to obtain more detaileddata. Of 50 patients identified. detailed responses werereceived regarding 40 patients (Appendix) who are thesubjects of this analysis. All patients underwent defibrillatorimplantation between October 1980 and November 1989.

Device selection. The first patient received the originalautomatic implantable defibrillator (AID) model, whichsensed only sinusoidal ventricular tachycardia or ventricularfibrillation. Nine patients initially received the lntec AID-Bor AID-BR device. which became available in 1982. Allother patients received the CPI Ventak AICD. which be­came generally available in 1986.

Definitions. For the purpose of this study, the followingdefinitions were used:

Sudden cardiac death: the abrupt cessation of respiratoryand circulatory function due to underlying cardiac disease.

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PATIENT AGE (Years)

KRON ET AL.DEFIBRtLLATORS IN YOUNG PATIENTS

OTHER(3)

HeM(6)

LONG QT(7)

897

Figure I. Distribution of ages of 40 young patients who received anautomatic implantable cardioverter-defibrillator. The median agewas 15 years.

Sustained I'entricular tachycardia: ventricular tachycar­dia >30 s in duration or requiring termination due to hemo­dynamic deterioration.

Clinicall'entricular tach.vcardia: ventricular tachycardiainduced by programmed electrical stimulation that was ei­ther clinically documented or was considered compatiblewith the patient's clinical presentation.

Nonclinical I'entricular tachycardia: ventricular tachy­cardia induced by programmed electrical stimulation thathad not been clinically documented and. in the opinion of theresponding physician. was not compatible with the patient'sclinical presentation.

Ventricular fibril/ation: random. chaotic electrical activ­ity of the ventricles with no associated cardiac output.

Appropriate shock: a defibrillator shock that. in theopinion of the responding physician. was delivered in re­sponse to a sustained ventricular tachyarrhythmia.

Spurious shock: a defibrillator shock that. in the opinionof the responding physician. was delivered for reasons otherthan a sustained ventricular tachyarrhythmia.

Indeterminate slwck: a defibrillator shock that could notbe classified as appropriate or spurious.

Statistical analysis. All data are presented as median ormean values ± SD unless otherwise specified. Life tableanalysis of survival was performed by the Kaplan-Meiermethod.

ResultsPatient characteristics. The group consisted of 25 male

and 15 female patients with a median age of 15 years (range8 to 19) (Fig. I). The median weight was 56 kg (range 30 to86). The indications for device implantation were abortedsudden cardiac death due to ventricular fibrillation or hy­potensive ventricular tachycardia (n = 35). drug refractoryventricular tachycardia (n = 2). syncope with induciblemonomorphic ventricular tachycardia at electrophysiologicstudy (n == I) and a strong family history of sudden cardiac

FAMILIAL SD(2)

Figure 2. Associated cardiovascular diagnoses. CHD = congenitalheart disease: DCM = dilated cardiomyopathy: HCM = hyper­trophic cardiomyopathy: SD = sudden death: 1° VF = primaryventricular fibrillation: Numbers in parentheses indicate number ofpatients.

death and inducible ventricular fibrillation at the time ofelectrophysiologic study (n = 2).

Associated cardiovascular diagnoses. Twenty-two pa­tients had identifiable structural heart disease: the mostprevalent diagnosis was dilated or hypertrophic cardiomy­opathy (\5 patients: Fig. 2). Four of the 22 patients hadcongenital heart disease and three of the four had a history ofprior corrective surgery. One of the four patients had com­plex anomalous pulmonary venous return associated withdilated cardiomyopathy: one had transposition of the greatvessels with double outlet right ventricle and one hadtransposition with a ventricular septal defect and pulmonarystenosis. The fourth patient had isolated corrected transpo­sition with congenital complete heart block for which apacemaker had previously been placed. In three other pa­tients the diagnosis was arrhythmogenic right ventriculardysplasia. Kawasaki's disease and mitral valve prolapse.respectively.

The other 18 patients Iwd {/II underlying electrical abnor­mality. Nine had primary ventricular fibrillation. seven hadcongenital long QT syndrome and two had a strong familyhistory of sudden cardiac arrest.

Ventricular fil/lction. as estimated by angiographic orechocardiographic techniques. was normal in 25 patients.reduced in 7 and not available in 8.

Preimplant electrophysiologic study. Before defibrillatorimplantation. 36 patients underwent an electrophysiologicstudy. Sustained ventricular tachyarrhythmias were inducedin 20 patients including ventricular fibrillation in 13 andventricular tachycardia that was believed to represent theclinical arrhythmia in 8 patients. Two patients had ventric­ular tachycardia induced that was not believed to representclinical arrhythmia. No ventricular tachyarrhythmias wereinduced in 16 patients.

Thirt.\' (If" the 35 surl'il"ors II( aborted .\udden death had

898 KRON ET AL.DEFIBRILLATORS IN YOUNG PATIENTS

lACC Vol. 16. No.4October 1990:896-902

Table 2. Concomitant Drug Therapy in 40 Patients

Table I. Profile of Shocks Delivered by the ImplantableDefibrillator in 40 Patients

in five patients. Lead fracture necessitating lead replacementoccurred in two patients and pocket erosion requiring gen­erator site revision occurred in one patient.

Psycholo[?ic acceptance of the device has been difficultj(Jr some patients. One patient dropped out of school be­cause of psychologic difficulties. Two patients requesteddevice explantation including the patient with pocket ero­sion, who refused AICD reimplantation after explantation ofthe original device.

Profile of defibrillator discharges (Table 1). During amedian follow-up period of 29 months after AICD implanta­tion. one or more defibrillator discharges occurred in 28(70%) of the 40 patients. Seventeen patients (42.5%) experi­enced at least one appropriate shock. whereas II (27.5%)received only spurious or indeterminate shocks. Twelvepatients (30%) have experienced no defibrillator shocks. Thenumber of shocks experienced by each patient ranged fromI to 40 (mean 10.1 ± 10).

Concomitant drug therapy (Table 2). After defibrillatorplacement. pharmacologic therapy was continued for 30

ventricular fibril/ation as the presenting arrhythmia. Ven­tricular fibrillation was induced in 10 (33%) of the 30 patientswith documented ventricular fibrillation. Of the other 20, Ihad sustained ventricular tachycardia induced, 16 (53%) hadno inducible arrhythmias and 3 did not undergo electrophys­iologic study. Of the five survivors of sudden death withhypotensive ventricular tachycardia as the presenting ar­rhythmia, three had inducible ventricular tachycardia, onehad no arrhythmias induced and one did not undergo elec­trophysiologic study. Both patients with drug-refractoryventricular tachycardia and the patient with syncope hadsustained monomorphic ventricular tachycardia induced.The two patients with a strong family history of suddendeath had inducible ventricular fibrillation.

Surgical considerations. The most common surgical ap­proach was a lateral thoracotomy, which was used in 22patients (56%). A midline sternotomy was used in 12 patients(31%) and a subcostal or subxiphoid incision was used in 3(8%) and 2 (5%) of the patients, respectively. Data withregard to patch size were available for 36 patients. Thedefibrillation lead configuration was small patch (10 cm2

)­

small patch in 14 patients (39%), large patch (20 cm2)-smallpatch in 12 patients (33%) and large patch-large patch in 2patients (6%). A spring-patch configuration was used ineight patients (22%); a large patch was used in five of theeight patients receiving a spring-patch configuration. Epicar­dial rate-sensing electrodes were used in 87% of the patients.

All patients had adequate defibrillation thresholds, whichranged from 2to 20 J. Concomitant surgery included divisionof an accessory pathway, coarctation repair, myocardial/lung biopsy and left stellate ganglionectomy in one patienteach.

Concomitant pacemakers. Six (15%) of the patients alsoreceived a pacemaker. Two of these had a bipolar dualchamber unit, two had an antitachycardia pacemaker withVVI backup, one had a VVIR unit and one had an AAI-MBoverdrive pacemaker for the management of recurrent atrialflutter.

Early complications. Complications that occurred beforehospital discharge included pericardial effusion in two pa­tients and phrenic paralysis, pneumothorax and hematomarequiring transfusion in one patient each. One other patienthad tracheal stenosis that was attributed to prolonged intu­bation after the patient's initial aborted sudden cardiacdeath. Two patients had defibrillator system malfunctionsthat were noted at the predischarge electrophysiologicstudy. These included pulse generator failure that necessi­tated generator replacement in one patient and excessivedefibrillation threshold that was corrected by changing froma patch-patch to a spring-patch configuration in one otherpatient.

Late complications. The most common problems experi­enced after hospital discharge have been lead related. Over­or undersensing of the patient's QRS complexes was noted

Discharge Category

Appropriate onlyAppropriate and spuriousAppropriate and indeterminateSpurious onlySpurious and indeterminateIndeterminate onlyNone

Total

See text for definitions of discharge categories.

Drug Therapy

Antiarrhythmic drugsProcainamidePhenytoinQuinidineDisopyramideFlecainidePropafenoneMexiletine + quinidineAmiodarone

Total

AV node blockersBeta-adrenergic blocking agentsVerapamilDigoxin + beta-adrenergic

blocking agent

Total

AV = atrioventricular.

No. of Patients (%)

12 (30)3 (7.5)2 (5)

6 (15)

1(2.5)4 (10)

12 (30)

40 (100)

No. of Patients (%)

1(2.5)1(2.5)1 (2.5)2 (51I (2.5)I (2.5)I (2.514 (10)

12 (30)

17 (42.5130.5)1 (2.5)

21 (52.5)

lACC Vol. 16, No.4October 1990:896-902

KRON ET AL.DEFIBRILLATORS IN YOUNG PATIENTS

899

SUDDEN DEATHS30

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n=10 n=10 n=8 V1 25>-Zw>= 20<l:a-t....0 15

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12 18 24 30 3. ., 48 DRIVING INFORMAL COMPETITIVE

FOLLOW UP (Months) PERMITTED ATHLETICS ATHLETICS

ALL DEATHS Figure 4. Activities permitted by patients' physicians after auto-matic implantable cardioverter-defibrillator implantation.

n-27 n:::24 n-18n=12

n=10 n=10 n_8

Figure 3. Survival of 40 young patients who received an automaticimplantable cardioverter-defibrillator. A, Actuarial sudden death­free survival. B, Total survival rate (see text for details). Numbersindicate number of patients at each follow-up period.

(75%) of the 40 patients, prescribed either for rate control ofsupraventricular rhythms or specific therapy to preventrecurrent ventricular tachyarrhythmias. Six of seven pa­tients with the congenital long QT syndrome continuedbeta-adrenergic blocking therapy after defibrillator implan­tation.

Long-term survival. There were a total of four deathsduring a median follow-up of 28.2 months. Two of thesedeaths were sudden: one in a patient who was water skiingagainst medical advice and the other in a patient whosustained significant neurologic damage after her initialcardiac arrest and whose parents were ambivalent regardingintensity of treatment and failed to comply with AICDgenerator replacement when it showed signs of batterydepletion.

There were two J1oJ1sudden deaths. One patient died ofprogressive congestive heart failure and one other patientdied secondary to complications after cardiac transplanta­tion.

Actuarial survival curves are shown in Figure 3. Sudden

12 18 H· 30 36

FOLLOW UP (Months)42 48

cardiac death-free survival rates at 12 and 33 months were0.94 and 0.88, respectively. Total survival at 12 and 33months was 0.94 and 0.82, respectively.

Life-style considerations. To determine whether defibril­lator therapy further impaired the patient's already limitedlife-style, implanting physicians were asked whether drivinga car or informal or competitive athletics were permitted(Fig. 4). Driving was allowed in 8 patients and was prohib­ited in 14; at least two patients continued to drive againstmedical advice. Competitive athletics were prohibited in 22(76%) of 29 patients, whereas informal athletics were al­lowed in 27 (84%) of 32 patients for whom information wasavailable. There was at least one pregnancy, resulting in thedelivery of a normal child. The mother received whatappeared to be an appropriate defibrillator shock during thethird trimester of pregnancy without apparent adverse con­sequences to the fetus.

DiscussionThe AICD can be effectively used in children and young

adults with a low surgical morbidity and a long-term out­come similar to that of older patients (8). However, experi­ence with the AICD in young patients is still quite limitedand the true long-term outcome of defibrillator therapy inpatients who may survive for decades is yet to be defined.Nevertheless, the AICD offers an important therapeuticoption for young patients with life-threatening ventriculartachyarrhythmias who have a relatively poor prognosisunless successful antiarrhythmic therapy can be defined(16,18).

Anatomic and surgical considerations. The patients in thissurvey differ anatomically from adult patients with an im­planted defibrillator, of whom approximately 75% haveunderlying coronary artery disease (8). The majority of theyounger patients have either some form of cardiomyopathy

900 KRON ET AL.DEFIBRILLATORS IN YOUNG PATIENTS

lACC Vol. 16. No.4October 1990:896-902

or a primary electrical abnormality and thus no history ofprior cardiac surgery. Therefore, in most cases surgery canbe performed via a lateral thoracotomy. Although few of ourpatients had complex congenital heart disease. they ap­peared to tolerate defibrillator implantation without signifi­cant additional morbidity. However, preoperative anatomicevaluation of all patients undergoing AICD implantation isappropriate to identify any potentially correctable lesionsthat can be repaired at the time of surgery.

Patient size does not appear to he a significant issue, withthe majority of patients having epicardial rate-sensing anddefibrillation electrodes placed without difficulty. In somecases, especially in patients with a history of prior cardiacsurgery, it may be necessary to utilize either transvenousrate-sensing or defibrillation spring electrodes. However. inmost cases the added complexity of transvenous leads ingrowing patients can be avoided. The weight of the CPImodel 1550 defibrillator is 235 g (19), which may present aproblem for smaller patients. It has been our practice toutilize a subrectus generator position for these patients.which has provided an acceptable cosmetic result and hasmade the patient acceptance of the device less of an issue.

Role of preoperative eIectrophysiologic study and the man­agement of patients with no inducible arrhythmias, It iscurrently standard practice to perform preoperative electro­physiologic studies in most patients undergoing defibrillatorimplantation (20). These studies may be useful in definingconcomitant pharmacologic therapy, providing more accu­rate device selection and programming and occasionallyidentifying patients with correctable electrical abnormalitiessuch as Wolff-Parkinson-White syndrome. Preoperativeelectrophysiologic studies may be less useful in patients withthe long QT syndrome (2L22) and in patients with dilatedcardiomyopathy in whom programmed ventricular stimula­tion has an uncertain prognostic and therapeutic role (23,24).

A prohlematic area regarding electrophysiologic testingis the management ofpatients with no inducihle I'entriculartachyarrhythmias. Depending on the series reported and thestatus of left ventricular function. these patients mayor maynot have a favorable long-term prognosis (25-28). In rela­tively young patients without severe underlying heart dis­ease, it may be fair to measure prognosis in decades. Therelatively good prognosis of 5% per year arrhythmia recur­rence in adults with no inducible tachyarrhythmias andrelatively normal hemodynamic status may not be accept­able in children (20.28). In the present series 16 patients hadno inducible ventricular arrhythmias at the time of electro­physiologic study and 2 other patients had what were con­sidered to be nonclinical arrhythmias induced. In follow-up.3 (17%) of these 18 patients experienced 2 to 14 appropriatedischarges and 3 others experienced 1 to 17 indeterminatedefibrillator discharges. Recently it was suggested (29) thatmany indeterminate shocks may actually be appropriate. Ifthese findings are corroborated. then 6 (33%) of the 18

patients in this series with noninducible arrhythmia wouldalready have had appropriate use of their devices. Becausepatients remain at continued risk of arrhythmia recurrence.perhaps other patients with no inducible arrhythmias willeventually experience shocks as well.

Role of concomitant drug therapy, Young patients with animplanted defibrillator may continue to require drug therapyeither to decrease the frequency of recurrent ventriculartachyarrhythmias or to prevent inappropriate shocks sec­ondary to sinus tachycardia or supraventricular tachyar­rhythmias. The frequency of antiarrhythmic therapy appearsto be similar to that in adult patients (6,8), although it islikely that the need for atrioventricular node blocking agentsmay be more frequent for younger patients. It has been ourpractice to treat younger patients with beta-adrenergicblocking therapy routinely after AICD implantation but toavoid specific antiarrhythmic therapy for patients who havehad infrequent ventricular tachyarrhythmias. Antiarrhyth­mic therapy can be added to the regimen of patients receiv­ing relatively frequent AICD shocks to improve patientcomfort and safety, as well as to enhance device longevity.

Life-style and psychosocial considerations. The majorityof patients and families have been very accepting of defibril­lator therapy and most patients have been able to resumenormal daily activities. However. some patients and familieshave found it difficult to comply with some of the life-styleand follow-up restrictions. For the most part. however, therestrictions are not imposed by the presence of the AICD butrather by the patients' arrhythmias and the known suscepti­bility to recurrence. Inability to follow recommendations hascontributed to a fatal outcome in some patients.

It is unclear whether young A/CD patients should heallowed to dril'c. Some patients will have syncope with theirarrhythmia before their device is activated; even in thosewho remain conscious, the discharge itself could renderthem accident prone. In this series there was no consensusamong implanting physicians as to whether driving should bepermitted. Although we have taken an inconsistent ap­proach, we currently discourage driving for these patientsand. even when driving is permitted, we forbid freeway use.

These issues make it essential that young patients andtheir families be counseled and given extensive psychologicsupport before and after implantation. It may be appropriatenot to place a defibrillator in the rare patient who is unlikelyto adjust to the restrictions on life-style imposed by theAICD.

Future considerations. Although the AICD appears torepresent an important advance in the management of youngpatients with life-threatening arrhythmias. there clearly is aneed for new devices that will facilitate the broader applica­tion of implantable defibrillator therapy to the youngerpatient (30). Potential developments include smaller deviceswith enhanced generator longevity. nonthoracotomy sys­tems, improved telemetry capabilities, combination devices

lACC Vol. 16. No.4October 1990:896-902

KRON ET AL.DEFIBRILLATORS IN YOUNG PATIENTS

901

with antitachycardia and bradycardia pacing capabilities andtachycardia detection algorithms that can distinguish su­praventricular from ventricular tachyarrhythmias. Little isknown about the long-term effects of patch electrodes on thegrowing heart or the effective longevity of these electrodes.Longitudinal follow-up of these patients will identify prob­lems and help facilitate the long-term management of theyoung survivor of sudden cardiac death who has undergonedefibrillator implantation.

We thank John Davis for preparation of the manuscript. Cynthia Morris. PhDfor assistance in statistical analysis and John H. McAnulty. MD for review ofthe manuscript.

AppendixSurvey responders

University of Alabama Hospital, Birmingham, AL: Andrew Epstein. MD.Baptist Memorial Hospital, Memphis, TN: Owen Hartness. MD.Barnes Hospital, St. Louis, MO: Bruce Lindsay. MD.Cedars Sinai Hospital, Los Angeles, CA: Daniel Oseran. MD.Children's Hospital, Philadelphia, PA: Victoria Veller. MD. Francis

Marchlinski. MD.University Hospitals of Cleveland, OH: Richard Henthorn. MD.University of Colorado, Denver, CO: David Mann. MD.Columbia Presbyterian Medical Center. New York. NY: 1. Thomas

Bigger. Jr.. MD. Mary Kral. PA-e. Alan Hordof. MD. HenrySpotnitz. MD.

Foothills Provincial General Hospital, Calgary. Alberta. Canada: AnneGillis. MD.

Good Samaritan Hospital. Los Angeles. CA: David Cannom. MD.Harborview Medical Center. Seattle. WA: Gust Bardy. MD.Henry Ford Hospital. Detroit. MI: Charles Webb. MD.H6pital Cantonal Universitaire. Geneva, Switzerland: M. Zimmerman. MD.Hospital of the University of Diisseldorf. Diisseldorf. Federal Republic of

Germany: Martin Borggrefe. MD.Lariboisiere Hospital. Paris. France: Philippe Coumel. MD.Loyola University. Chicago. IL: David Wilber. MD.Massachusetts General Hospital, Boston, MA: Jeremy Ruskin. MD.Millard Fillmore Hospital, Buffalo, NY: Donald Switzer. MD.Milwaukee City Medical Complex, Milwaukee. WI: Paul Troup. MD.Moffitt Hospital, San Francisco, CA: Jerry Griffin. MD.Monteliore Hospital, New York. NY: Gordon Kritzer. MD. John Fisher. MD.M!. Sinai Hospital. Milwaukee, WI: Mohammed Jazayeri. MD.Oregon Health Sciences Uninrsity. Portland. OR: John McAnulty. MD. Jack

Kron. MD. Michael Silka. MD.Sinai Hospital. Baltimore. MD: Enrico Veltri. MD. Linda J. Schenker. RN.Stanford University. Palo Alto, CA: Roger Winkle. MD. Jan Peterson. R

Charles Swerdlow. MD.University Hospital. London, Ontario. Canada: AIjun Sharma. MD.Vanderbilt University Hospital. Nashville. TN: John Lee. MD.Washington Hospital Center: Edward Platia. MD.Western Pennsylvania Hospital. Pittsburgh. PA: Barrv Alpert. MD.University of Virginia, Charlottesville. VA: Bruce Lerman. MD. John

DiMarco. MD.Westfalische Wilhelms·Universitat, Munich. Federal Republic of Germany:

Gunter Breithardt. MD.

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