984
Brief Communications
American
5. Benchimol A, Bartall H, Desser KB. Accelerated ventricular arrhythmia and cocaine abuse. Ann Intern Med 1978;88:51920. 6. Nanji AA, Filipenko JD. Asystole and ventricular fibrillation associated with cocaine intoxication. Chest 1984;85:132-3. 7. Jervell A, Lange-Neilsen F. Congenital deaf mutism; functional heart disease with prolongation of the QT interval and sudden death. AM HEART J 1957;54:59-68. 8. Ward OC. A new familial cardiac syndrome in children. J Irish Med Assoc 1964;54:103-6. 9. Schwartz PJ et al. Idiopathic long QT syndrome: progress and questions. AM HEART J 1985;109:399-411. 10. Wellens HJJ, Vermuelen A, Durrer D. Ventricular fibrillation occurring on arousal from sleep by auditory stimuli. Circulation 1972;46:661-5.
Conduction system disease in a child with long QT syndrome L. Case,MD, and Paul C. Gillette, MD. Charleston. SC. Christopher
Evidence of atrioventricular (AV) conduction abnormalities in associationwith the long QT syndrome (LQTS) has been reported in the clinical and pathologic literature. Fatty infiltration of the AV node and fibrosis of the His bundle have been noted in pathologic sectionsof patients with documented
prolonged
QT interva1s.l
Two-to-one
AV
block in infants with LQTS has also been reported, with subsequentresolution asthe intrinsic sinusrate decreased with aging.2Evidence of intra-Hisian conduction system diseasehas also been documented in two adult patients with hereditary LQTS.3 We herein report a caseof a young child with LQTS who had abnormalities of the sinusnode, the infranodal conduction system, and ventricular myocardium documented by invasive electrophysiology and biopsy. The patient was a 6- % -year-old white boy who wasfollowed since birth with LQTS. He had been started on a regimenof propranolol as an infant. He tolerated the drug for 4 years but then started to experience frequent nightmares.He wasswitched to atenolol, and took it for 2 years before he started to have visual disturbances and headaches.While receiving ,&blockers, he never experienced a syncopal episode.The rest of the child’s cardiovascular history wasunremarkable. Physical examination wasnormal, except for a slow resting heart rate. An echocardiogram as a neonate revealed questionable mild subaortic outflow obstruction, which resolved by the age of 5 years. A low shortening fraction wasintermittently documented by echocardiography with an otherwise normal structural heart. The electrocardiogram consistently showed sinus From South Carolina Children’s Heart Center, Medical University Carolina. Reprint requests: Christopher L. Case, MD, Pediatric Cardiology, ley Ave., Charleston, SC 29425. 414122907
of South 171 Ash-
October 1990 Heart Journal
bradycardia, with a rate of 50 per minute, and a markedly abnormalQT interval of 690 msec,with a QT, of 630msec. At the age of 6 years, an exercisetest showeda decreased enduranceof 6 minutes, with a maximum heart rate of 110 beats/min and variable AV conduction. At this time, the patient started to experience increasing presyncopal episodes.Transtelephonic monitoring during these episodes revealed sinus bradycardia, with a rate of slightly more than 40 per minute. The child never had any episodesof ventricular tachycardia and/or fibrillation recorded on Holter monitor or via transtelephonic monitoring. In view of the increasing presyncopal symptoms, the echocardiographic evidenceof compromisedventricular function, and documentedbradycardia, it wasthought necessaryto perform cardiac catheterization in order to investigate his electrophysiologic substrate,aswell asto obtain a myocardial biopsy specimen. A complete right-sided heart catheterization was done, which revealed normal pressures,saturations, and a mean pulmonary artery wedgepressureof 8 mm Hg. A myocardial biopsy wasperformed. The resultswereread asnormal yet showedminor, nonspecificchangesconsistingof a disarray of musclefibers and minor focal lymphocytic infiltration. Electrophysiologic study revealed a mildly abnormal maximum corrected sinusrecovery time of 512 msec, a sinoatrial conduction time of 196msec,and an atria1 refractory period of 260msec.There wasa normal AH interval of 72 msec.Two-to-one block below the His bundle occurred during pacing at 100 beats/min (Fig. 1). The AV nodal effective refractory period was 500 msec, and the functional refractory period was510msec.The resting HV interval was49 msecand the His-Purkinje systemeffective refractory period was580msec.The ventricular refractory period measured490msecat a pacing cycle length of 1000 msec. No ventricular dysrhythmias were induced with a standard atria1 and ventricular protocol. The diagnosisafter this catheterization included (1) mild sinus node dysfunction, (2) His-Purkinje system dysfunction, (3) LQTS, and (4) biopsy evidence of mild myocardial abnormalities. The child wasplaced on a regimen of atenolol yet continued to have presyncopal episodes.Transtelephonic monitoring of his presyncopalepisodesrevealedcontinued sinus bradycardia. In view of his continuing symptoms,it wasfelt that the patient might benefit from pacing. Four months after his initial catheterization, the child underwent a successfulimplantation of a dual-chambered rate responsive pacemaker. Prior to insertion of this pacemaker, he had monophasicaction potentials recorded from the right ventricle (Fig. 2). This procedure was well tolerated and the patient wasdischargedhomeon his original atenolol dose. He displayed normal pacemaker function at a 2-month follow-up, yet died suddenly 3 monthsfollowing pacemaker implantation. He was found in ventricular fibrillation and could not be resuscitated.Normal pacemakerfunction was noted during resuscitation attempts. Permission for autopsy was refused. The pathophysiologic mechanismsresponsiblefor the life-threatening arrhythmias associated with LQTS are
Volume Number
120 4
Brief Communications
985
1. ECG tracing illustrating two-to-one AV block below the His bundle in the patient documented during atrial pacing at 600 mseccycle length during electrophysiology study. S, Stimulus; HRA, high right atrium; HBE, His bundle electrogram; H, His electrogram.
Fig.
2. Monophasic action potential of the right ventricle of the patient with long QT syndrome.Note that the length of the ventricular depolarization correspondswith the duration of the QT interval. The QT interval measures650 msec,while the action potential duration measures600 msec. Fig.
poorly understood. There is experimental as well asclinical evidence that an imbalance of the sympathetic innervation of the heart is a critical element in the etiology of ventricular dysrhythmias associatedwith LQTS. The as-
sociationbetweenfunctional conduction systemabnormalities and the clinical spectrum of LQTS has also been reported.4Pathologic specimensof patients dying from this syndrome have shown abnormalities of the AV node, the
966
Brief Communications
American
His-Purkinje system, and even the ventricular myocardium.l The above-reported caseillustrates functional as well as biopsy-confirmed abnormalities associatedwith LQTS in a child. This patient showedelectrophysiologic dysfunction in the sinusnode and His-Purkinje system,as evidenced by invasive electrophysiology. He alsoexhibited ventricular myocardial abnormalities, asshownby biopsy. Bharati et al.’ have reported similar findings in pathologic specimensof ventricular myocardium from patients with LQTS, yet they attributed thesefindings asbeing secondary to the vigorous resuscitation of such patients. Our patient had undergoneno resuscitation prior to biopsy. Aberrations of AV conduction associatedwith this syndrome have been previously demonstrated in infants and in a fetus.z 5Also, abnormalitiesof intra-Hisian conduction have been documented by invasive electrophysiology in adults with LQTS3 This report outlines similar infranodal conduction systemdiseasein a child, aswell as evidenceof sinus node and ventricular myocardial abnormalities. Whether the structural and functional abnormalities seen in this child are secondaryto a commonpathologic process cannot be answered by this report. It is interesting, however, that in this particular casethere wasevidence of conduction system abnormalities in multiple areasof the heart. Whether this global conduction systemdysfunction contributed to the patient’s erratic and poor clinical outcome is an interesting yet purely speculative reflection. REFERENCES
1.
2. 3. 4.
5.
Bharati S, Dreifus L, Bucheleres G, et al. The conduction system in patients with a prolonged QT interval. J Am Co11Cardiol 1985;6:1110-19. Scott W, Dick M II. Two: one AV block in infants with congenital long QT syndrome. Am J Cardiol 1987;60:1409-10. Greenspon A, Kidwell G, Barrasse L, Hessen SL, Guidici M. Hereditary long QT syndrome associated with cardiac conduction system-disease. PACE 1989;12:479-85. Schwartz P. Milliani A. Electrical alteration of the T wave: clinical and’experimental evidence of its relationship with the sympathetic nervous system and the long QT syndrome. AM HEART J 1975;89:45-50. Presbitero P, Mangiardi L, Antolini R. Congenital long QT syndrome inducing 2:l atrioventricular block: early detection in fetal life. Int J Cardiol 1989;24:109-12.
AV blockade via selective injection in a patient
AV nodal artery
Jodie L. Hurwitz, MD, Ronald J. Kanter, MD, Paul Gurbel, MD, Ruth Ann Greenfield, MD, Jack H. Kasell, and Charles J. Davidson, MD. Durham,
N.C.
From the
Department Center.
Medical Supported and Blood ing grants.
in part Institute,
Reprint requests: ter, Department NC 27710. 4/4/22908
of Medicine,
Division
of Cardiology,
by National Institutes of Health, and National Research Service Charles J. Davidson, of Medicine, Division
Duke
University
National Heart, Award HL07101
MD, Duke University of Cardiology, Box
Lung, train-
Medical Cen31195, Durham,
October 1990 Heart Journal
Transcatheter direct current His ablation hasbeenusedto treat atria1fibrillation with rapid ventricular response,and intracardiac direct-current electrical atrioventricular (AV) node modification has been employed to treat AV nodal reentrant tachycardia. l-3 The His potential can be extremely variable or at times impossibleto isolate.Blind direct cardioversion in the generalarea of the AV node is often not successful.Ethanol has beenused in the coronary circulation in humansin an effort to treat refractory ventricular tachycardia.4 Selective catheterization of the AV nodal artery followed by chemical ablation using ethanol injection could potentially prevent recurrences of rapid ventricular responseto atria1 fibrillation as well as potentially modify AV nodal conduction in patients with AV nodal reentrant tachycardia such that no further medical therapy is necessary.In this report, we demonstratethat it is possibleto safely and transiently block AV nodal transmissionby percutaneous catheter injection of iced saline into the AV nodal artery in humans. R.C. is a 38-year-old womanwho hashad 15years of palpitations secondary to supraventricular tachycardia. In 1985,she had an extensive electrophysiologic evaluation and wasfound to have atrio-Hisian and fasiculoventricular accessory pathways. She was treated unsuccessfully with verapamil, quinidine, and procainamide. Argon photoablation of her atrio-Hisian fiber and AV node resulted in transient complete heart block, necessitatingpermanent pacemaker placement. AV conduction returned in early 1989with recurrenceof supraventricular tachycardia along with atria1 fibrillation with a rapid ventricular response. She wasstarted on sotalol with somerelief, but wasrehospitalized with recurrencestaking 160mg eachmorning and 80 mg each evening. Her 12-leadelectrocardiogram upon admissionrevealed 95% ventricular pacing with rare conducted narrow beats and a short PR interval. Consideration was given to transcatheter direct-current AV node ablation; prior to this procedure,sheconsentedto AV nodal artery injection with iced saline.In the fasting, nonsedated state, two quadripolar electrode catheters (USC1Division of C.R. Bard, Billerica, Mass.) were placed under fluoroscopicguidancevia her left femoral vein into the right ventricle and right atrium and one tripolar electrode catheter was placed across the tricuspid valve to record a His potential. After multiple unsuccessfulattempts to locate a His potential, a large His deflection wasobtained with the catheter in an atypical position. Her permanent ventricular pacemakerwasprogrammedto a rate of 50 beats/min. A diagnostic cardiac catheterization was performed that demonstrated right dominant normal coronary arteries and an ejection fraction of 60%. After intravenous administration of 12,000units of heparin, an 8F, 4 cm Judkins right guiding catheter (Shiley Inc, Irvine, Calif.) wasplacedthrough an SFarterial sheath and was advanced into the right coronary artery. Under fluoroscopic guidance, an 0.018-inch high-torque floppy guide wire (Advanced Cardiovascular Systems,Temecula, Calif.) waspositioned into the AV nodal artery. A Tracker-18 high-flow infusion catheter (Target Therapeutics, San Jose, Calif.) was advanced to a nonocclusive position in the posterior descendingartery. Despite an aggressive pacing protocol including pacingfrom the ventricle and the
Brief Communications
American
5. Benchimol A, Bartall H, Desser KB. Accelerated ventricular arrhythmia and cocaine abuse. Ann Intern Med 1978;88:51920. 6. Nanji AA, Filipenko JD. Asystole and ventricular fibrillation associated with cocaine intoxication. Chest 1984;85:132-3. 7. Jervell A, Lange-Neilsen F. Congenital deaf mutism; functional heart disease with prolongation of the QT interval and sudden death. AM HEART J 1957;54:59-68. 8. Ward OC. A new familial cardiac syndrome in children. J Irish Med Assoc 1964;54:103-6. 9. Schwartz PJ et al. Idiopathic long QT syndrome: progress and questions. AM HEART J 1985;109:399-411. 10. Wellens HJJ, Vermuelen A, Durrer D. Ventricular fibrillation occurring on arousal from sleep by auditory stimuli. Circulation 1972;46:661-5.
Conduction system disease in a child with long QT syndrome L. Case,MD, and Paul C. Gillette, MD. Charleston. SC. Christopher
Evidence of atrioventricular (AV) conduction abnormalities in associationwith the long QT syndrome (LQTS) has been reported in the clinical and pathologic literature. Fatty infiltration of the AV node and fibrosis of the His bundle have been noted in pathologic sectionsof patients with documented
prolonged
QT interva1s.l
Two-to-one
AV
block in infants with LQTS has also been reported, with subsequentresolution asthe intrinsic sinusrate decreased with aging.2Evidence of intra-Hisian conduction system diseasehas also been documented in two adult patients with hereditary LQTS.3 We herein report a caseof a young child with LQTS who had abnormalities of the sinusnode, the infranodal conduction system, and ventricular myocardium documented by invasive electrophysiology and biopsy. The patient was a 6- % -year-old white boy who wasfollowed since birth with LQTS. He had been started on a regimenof propranolol as an infant. He tolerated the drug for 4 years but then started to experience frequent nightmares.He wasswitched to atenolol, and took it for 2 years before he started to have visual disturbances and headaches.While receiving ,&blockers, he never experienced a syncopal episode.The rest of the child’s cardiovascular history wasunremarkable. Physical examination wasnormal, except for a slow resting heart rate. An echocardiogram as a neonate revealed questionable mild subaortic outflow obstruction, which resolved by the age of 5 years. A low shortening fraction wasintermittently documented by echocardiography with an otherwise normal structural heart. The electrocardiogram consistently showed sinus From South Carolina Children’s Heart Center, Medical University Carolina. Reprint requests: Christopher L. Case, MD, Pediatric Cardiology, ley Ave., Charleston, SC 29425. 414122907
of South 171 Ash-
October 1990 Heart Journal
bradycardia, with a rate of 50 per minute, and a markedly abnormalQT interval of 690 msec,with a QT, of 630msec. At the age of 6 years, an exercisetest showeda decreased enduranceof 6 minutes, with a maximum heart rate of 110 beats/min and variable AV conduction. At this time, the patient started to experience increasing presyncopal episodes.Transtelephonic monitoring during these episodes revealed sinus bradycardia, with a rate of slightly more than 40 per minute. The child never had any episodesof ventricular tachycardia and/or fibrillation recorded on Holter monitor or via transtelephonic monitoring. In view of the increasing presyncopal symptoms, the echocardiographic evidenceof compromisedventricular function, and documentedbradycardia, it wasthought necessaryto perform cardiac catheterization in order to investigate his electrophysiologic substrate,aswell asto obtain a myocardial biopsy specimen. A complete right-sided heart catheterization was done, which revealed normal pressures,saturations, and a mean pulmonary artery wedgepressureof 8 mm Hg. A myocardial biopsy wasperformed. The resultswereread asnormal yet showedminor, nonspecificchangesconsistingof a disarray of musclefibers and minor focal lymphocytic infiltration. Electrophysiologic study revealed a mildly abnormal maximum corrected sinusrecovery time of 512 msec, a sinoatrial conduction time of 196msec,and an atria1 refractory period of 260msec.There wasa normal AH interval of 72 msec.Two-to-one block below the His bundle occurred during pacing at 100 beats/min (Fig. 1). The AV nodal effective refractory period was 500 msec, and the functional refractory period was510msec.The resting HV interval was49 msecand the His-Purkinje systemeffective refractory period was580msec.The ventricular refractory period measured490msecat a pacing cycle length of 1000 msec. No ventricular dysrhythmias were induced with a standard atria1 and ventricular protocol. The diagnosisafter this catheterization included (1) mild sinus node dysfunction, (2) His-Purkinje system dysfunction, (3) LQTS, and (4) biopsy evidence of mild myocardial abnormalities. The child wasplaced on a regimen of atenolol yet continued to have presyncopal episodes.Transtelephonic monitoring of his presyncopalepisodesrevealedcontinued sinus bradycardia. In view of his continuing symptoms,it wasfelt that the patient might benefit from pacing. Four months after his initial catheterization, the child underwent a successfulimplantation of a dual-chambered rate responsive pacemaker. Prior to insertion of this pacemaker, he had monophasicaction potentials recorded from the right ventricle (Fig. 2). This procedure was well tolerated and the patient wasdischargedhomeon his original atenolol dose. He displayed normal pacemaker function at a 2-month follow-up, yet died suddenly 3 monthsfollowing pacemaker implantation. He was found in ventricular fibrillation and could not be resuscitated.Normal pacemakerfunction was noted during resuscitation attempts. Permission for autopsy was refused. The pathophysiologic mechanismsresponsiblefor the life-threatening arrhythmias associated with LQTS are
Volume Number
120 4
Brief Communications
985
1. ECG tracing illustrating two-to-one AV block below the His bundle in the patient documented during atrial pacing at 600 mseccycle length during electrophysiology study. S, Stimulus; HRA, high right atrium; HBE, His bundle electrogram; H, His electrogram.
Fig.
2. Monophasic action potential of the right ventricle of the patient with long QT syndrome.Note that the length of the ventricular depolarization correspondswith the duration of the QT interval. The QT interval measures650 msec,while the action potential duration measures600 msec. Fig.
poorly understood. There is experimental as well asclinical evidence that an imbalance of the sympathetic innervation of the heart is a critical element in the etiology of ventricular dysrhythmias associatedwith LQTS. The as-
sociationbetweenfunctional conduction systemabnormalities and the clinical spectrum of LQTS has also been reported.4Pathologic specimensof patients dying from this syndrome have shown abnormalities of the AV node, the
966
Brief Communications
American
His-Purkinje system, and even the ventricular myocardium.l The above-reported caseillustrates functional as well as biopsy-confirmed abnormalities associatedwith LQTS in a child. This patient showedelectrophysiologic dysfunction in the sinusnode and His-Purkinje system,as evidenced by invasive electrophysiology. He alsoexhibited ventricular myocardial abnormalities, asshownby biopsy. Bharati et al.’ have reported similar findings in pathologic specimensof ventricular myocardium from patients with LQTS, yet they attributed thesefindings asbeing secondary to the vigorous resuscitation of such patients. Our patient had undergoneno resuscitation prior to biopsy. Aberrations of AV conduction associatedwith this syndrome have been previously demonstrated in infants and in a fetus.z 5Also, abnormalitiesof intra-Hisian conduction have been documented by invasive electrophysiology in adults with LQTS3 This report outlines similar infranodal conduction systemdiseasein a child, aswell as evidenceof sinus node and ventricular myocardial abnormalities. Whether the structural and functional abnormalities seen in this child are secondaryto a commonpathologic process cannot be answered by this report. It is interesting, however, that in this particular casethere wasevidence of conduction system abnormalities in multiple areasof the heart. Whether this global conduction systemdysfunction contributed to the patient’s erratic and poor clinical outcome is an interesting yet purely speculative reflection. REFERENCES
1.
2. 3. 4.
5.
Bharati S, Dreifus L, Bucheleres G, et al. The conduction system in patients with a prolonged QT interval. J Am Co11Cardiol 1985;6:1110-19. Scott W, Dick M II. Two: one AV block in infants with congenital long QT syndrome. Am J Cardiol 1987;60:1409-10. Greenspon A, Kidwell G, Barrasse L, Hessen SL, Guidici M. Hereditary long QT syndrome associated with cardiac conduction system-disease. PACE 1989;12:479-85. Schwartz P. Milliani A. Electrical alteration of the T wave: clinical and’experimental evidence of its relationship with the sympathetic nervous system and the long QT syndrome. AM HEART J 1975;89:45-50. Presbitero P, Mangiardi L, Antolini R. Congenital long QT syndrome inducing 2:l atrioventricular block: early detection in fetal life. Int J Cardiol 1989;24:109-12.
AV blockade via selective injection in a patient
AV nodal artery
Jodie L. Hurwitz, MD, Ronald J. Kanter, MD, Paul Gurbel, MD, Ruth Ann Greenfield, MD, Jack H. Kasell, and Charles J. Davidson, MD. Durham,
N.C.
From the
Department Center.
Medical Supported and Blood ing grants.
in part Institute,
Reprint requests: ter, Department NC 27710. 4/4/22908
of Medicine,
Division
of Cardiology,
by National Institutes of Health, and National Research Service Charles J. Davidson, of Medicine, Division
Duke
University
National Heart, Award HL07101
MD, Duke University of Cardiology, Box
Lung, train-
Medical Cen31195, Durham,
October 1990 Heart Journal
Transcatheter direct current His ablation hasbeenusedto treat atria1fibrillation with rapid ventricular response,and intracardiac direct-current electrical atrioventricular (AV) node modification has been employed to treat AV nodal reentrant tachycardia. l-3 The His potential can be extremely variable or at times impossibleto isolate.Blind direct cardioversion in the generalarea of the AV node is often not successful.Ethanol has beenused in the coronary circulation in humansin an effort to treat refractory ventricular tachycardia.4 Selective catheterization of the AV nodal artery followed by chemical ablation using ethanol injection could potentially prevent recurrences of rapid ventricular responseto atria1 fibrillation as well as potentially modify AV nodal conduction in patients with AV nodal reentrant tachycardia such that no further medical therapy is necessary.In this report, we demonstratethat it is possibleto safely and transiently block AV nodal transmissionby percutaneous catheter injection of iced saline into the AV nodal artery in humans. R.C. is a 38-year-old womanwho hashad 15years of palpitations secondary to supraventricular tachycardia. In 1985,she had an extensive electrophysiologic evaluation and wasfound to have atrio-Hisian and fasiculoventricular accessory pathways. She was treated unsuccessfully with verapamil, quinidine, and procainamide. Argon photoablation of her atrio-Hisian fiber and AV node resulted in transient complete heart block, necessitatingpermanent pacemaker placement. AV conduction returned in early 1989with recurrenceof supraventricular tachycardia along with atria1 fibrillation with a rapid ventricular response. She wasstarted on sotalol with somerelief, but wasrehospitalized with recurrencestaking 160mg eachmorning and 80 mg each evening. Her 12-leadelectrocardiogram upon admissionrevealed 95% ventricular pacing with rare conducted narrow beats and a short PR interval. Consideration was given to transcatheter direct-current AV node ablation; prior to this procedure,sheconsentedto AV nodal artery injection with iced saline.In the fasting, nonsedated state, two quadripolar electrode catheters (USC1Division of C.R. Bard, Billerica, Mass.) were placed under fluoroscopicguidancevia her left femoral vein into the right ventricle and right atrium and one tripolar electrode catheter was placed across the tricuspid valve to record a His potential. After multiple unsuccessfulattempts to locate a His potential, a large His deflection wasobtained with the catheter in an atypical position. Her permanent ventricular pacemakerwasprogrammedto a rate of 50 beats/min. A diagnostic cardiac catheterization was performed that demonstrated right dominant normal coronary arteries and an ejection fraction of 60%. After intravenous administration of 12,000units of heparin, an 8F, 4 cm Judkins right guiding catheter (Shiley Inc, Irvine, Calif.) wasplacedthrough an SFarterial sheath and was advanced into the right coronary artery. Under fluoroscopic guidance, an 0.018-inch high-torque floppy guide wire (Advanced Cardiovascular Systems,Temecula, Calif.) waspositioned into the AV nodal artery. A Tracker-18 high-flow infusion catheter (Target Therapeutics, San Jose, Calif.) was advanced to a nonocclusive position in the posterior descendingartery. Despite an aggressive pacing protocol including pacingfrom the ventricle and the
