European Heart Journal (1992) 13, 1080-1083
Congenital complete heart block associated with QT prolongation F. SOLTI, L. SZATMARY, T. VECSEY, F. RENYI-VAMOS jr. AND E. BODOR
KEY WORDS: Complete AV block, QT interval, ventricular polymorphous tachycardia, pacemaker therapy.
Downloaded from https://academic.oup.com/eurheartj/article-abstract/13/8/1080/435214 by University of West London user on 23 November 2018
Cardiovascular Surgical Clinic, Semmelweis Medical University, Budapest, Hungary
The coexistence of congenital complete heart block and QT prolongation represents a special type of arrhythmia. The electrophysiological and clinical characteristics of this syndrome were studied in eight patients suffering from congential A V block and QT prolongation. Data from 22 patients suffering from congenital complete heart block only, served as a control. In the study group, the appearance of a torsade de pointes type of ventricular tachycardia could regularly be observed and the tachycardial attack could usually be provoked by ventricular extrastimuli. The corrected Q T time was markedly prolonged; on ventricular stimulation, at higher pacing rates the QT interval shortened, but remained significantly higher than in the control group. Syncopal attacks — with the character of polymorphic tachycardia — appeared in each patient of the study group while occurring in only three patientsfrom the control group. Patients were given pacemaker implants (using a higher pacing rate) and long-term administration of ^-receptor blockers. The outcome was favourable; no ventricular tachycardia or syncopal attack was observed in the follow-up period. Introduction Congenital heart block is a rare and special form of complete AV block. The QRS complex is narrow, the ventricular automaticity rate is comparatively high and the development of Adams-Stokes attacks can only be observed in exceptional cases. The prevalence of congenital complete heart block is approximately 3-4% of all forms of third degree AV block'1"*1, and the association of QT interval prolongation can be detected in some cases of second and third degree AV blocks'7"131. A review of the scanty literature suggests that the appearance of QT prolongation can alter the arrhythmic characteristics of complete AV block. In the present study eight patients suffering from congenital complete AV block associated with QT prolongation were observed. The study was undertaken to investigate the electrophysiological and clinical characteristics of congenital complete heart block with QT prolongation.
feature present in every family member of two of the patients. Twenty-two patients suffering from congenital complete heart block (with normal QT duration) formed the control group. The clinical data from the control group are outlined in Table 2. The criteria for congenital complete heart block were (1) bradycardia since childhood; (2) narrow QRS complexes; (3) an idioventricular pacemaker firing at a relatively high rate and (4) no congenital or acquired heart disease. A long QT interval was recognized when the heart-ratecorrected QT, interval (QTJ was markedly prolonged; 'QTC:> 460 ms'. The QT duration was measured from the onset of the QRS to the end of the T wave, defined as a return to the T-P baseline.Three consecutive cycles were measured and from the three values a mean QT was calculated'141. The QTC was measured by using Bazett's formula'151. A typical ECG tracing of congenital heart block with long QT duration is demonstrated in Fig. 1.
Methods PATIENT POPULATION
From 1963 to 1990,4418 first pacemaker implantations were performed in the Cardiovascular Surgical Clinic. In eight of these patients the association of QT prolongation with congenital complete heart block could be detected (study group). The most important clinical data from these patients are summarized in Table 1. A retrospective familial clinical history was obtained in seven of the cases and no familial long QT syndrome could be detected in any of them. A moderate QT prolongation without any clinical signs was noted in one patient's brother only, while first degree AV block was a Submitted for publication 21 November 1990 and in revised form 2 April 1991. Correspondence Francis Solti, Cardiovascular Surgical Clinic, H-1122 Budapest, Varosmajor Str 68, Hungary. 0195-668X/92/081080 + 04 $03 00/0
ELECTROPHYSIOLOGICAL STUDY
Before pacemaker implantation — to facilitate selection of a suitable pacing mode — an invasive electrophysiological study was performed in each patient of the study group and in 12 patients from the control group. All medication was withdrawn 48 h prior to the study. Informed consent was obtained from all patients. The electrophysiological testing consisted of programmed electrical stimulation of the heart and the recording of endocavital ECG tracings (intracardiac electrograms were recorded from the high right atrium, the His bundle region and the right ventricle). Electrical stimulation of the heart was perfomed by using a programmable digital stimulator (Medtronic 5325) that delivered rectangular impulses lasting 20ms at twice the diastolic threshold. © 1992 The European Society of Cardiology
Long Q T duration with permanent bradycardia 1081
Table 1 Clinical features of patients suffering from congenital total A V block accompanied with long QT duration g 17-7±5-87 5/3
42 ±6-8 485±32 640-48
(range 10-23) (range 38-60) (range 470-500) (range 560-690)
8
i i
Table 2 Clinical characteristics of patients suffering from congenital total A V block with normal QT duration Patients (N) Age (years) Sex (male/female) Heart rate (beats . min~') QT c (ms) QT(ms) Indication for pacemaker implantation Adams-Stokes syncopal attacks Signs of cardiac decompensation (heart enlargement, dyspnoea, exercise intolerance) Accompanying diseases Hypertension Diabetes mellitus
22 23-3 ±6-5 12/10 44 ±7-2 420 ±28 490 ±30
(range 10-30) (range 36-68) (range 390-450) (range 450-520)
3 19 2
1
Figure 1 Congenital AV block associated with QT prolongation demonstrated by surface ECG leads I-III, paper speed 25 mm . s~' and a total AV block with narrow QRS complex. PP = 660 ms, R R = 1400 ms. QT is markedly prolonged (690 ms). The QTC is also prolonged (580 ms)
For inducing ventricular tachycardia single and double ventricular extrastimuli were used. For studying the effect of the different cycle length on the QT duration, ventricular pacing was performed with a driving cycle length ranging from 600-1000 ms.
For statistical comparison of the study group data with that of the control group, the Student's t-test for unpaired data was applied. Patients were followed up after pacemaker implantation for a mean of 28 months (range 6-49 months).
Downloaded from https://academic.oup.com/eurheartj/article-abstract/13/8/1080/435214 by University of West London user on 23 November 2018
Patients (N) Age (years) Sex (male/female) Heart rate (beats. min"1) QT c (ms) QT(ms) Indication for pacemaker implantation Polymorphous ventricular tachycardia attacks with syncope Signs of cardiac decompensation Accompanying diseases Hypertension
1082 F. Solti et al.
550
500
--
450
-
%
o 400
-
t 350
J0O
n
NS
-
i
600
i
700 800 900 Pocing cycle length (mi)
1
1000
Figure 2 The effect of cycle length on QT duration. Asterisks = AV block with >QT, Open squares —AV block without >QT. Values are expressed as mean±SD. | / > < 0 0 1 . J/>
Congenital complete heart block associated with QT prolongation F. SOLTI, L. SZATMARY, T. VECSEY, F. RENYI-VAMOS jr. AND E. BODOR
KEY WORDS: Complete AV block, QT interval, ventricular polymorphous tachycardia, pacemaker therapy.
Downloaded from https://academic.oup.com/eurheartj/article-abstract/13/8/1080/435214 by University of West London user on 23 November 2018
Cardiovascular Surgical Clinic, Semmelweis Medical University, Budapest, Hungary
The coexistence of congenital complete heart block and QT prolongation represents a special type of arrhythmia. The electrophysiological and clinical characteristics of this syndrome were studied in eight patients suffering from congential A V block and QT prolongation. Data from 22 patients suffering from congenital complete heart block only, served as a control. In the study group, the appearance of a torsade de pointes type of ventricular tachycardia could regularly be observed and the tachycardial attack could usually be provoked by ventricular extrastimuli. The corrected Q T time was markedly prolonged; on ventricular stimulation, at higher pacing rates the QT interval shortened, but remained significantly higher than in the control group. Syncopal attacks — with the character of polymorphic tachycardia — appeared in each patient of the study group while occurring in only three patientsfrom the control group. Patients were given pacemaker implants (using a higher pacing rate) and long-term administration of ^-receptor blockers. The outcome was favourable; no ventricular tachycardia or syncopal attack was observed in the follow-up period. Introduction Congenital heart block is a rare and special form of complete AV block. The QRS complex is narrow, the ventricular automaticity rate is comparatively high and the development of Adams-Stokes attacks can only be observed in exceptional cases. The prevalence of congenital complete heart block is approximately 3-4% of all forms of third degree AV block'1"*1, and the association of QT interval prolongation can be detected in some cases of second and third degree AV blocks'7"131. A review of the scanty literature suggests that the appearance of QT prolongation can alter the arrhythmic characteristics of complete AV block. In the present study eight patients suffering from congenital complete AV block associated with QT prolongation were observed. The study was undertaken to investigate the electrophysiological and clinical characteristics of congenital complete heart block with QT prolongation.
feature present in every family member of two of the patients. Twenty-two patients suffering from congenital complete heart block (with normal QT duration) formed the control group. The clinical data from the control group are outlined in Table 2. The criteria for congenital complete heart block were (1) bradycardia since childhood; (2) narrow QRS complexes; (3) an idioventricular pacemaker firing at a relatively high rate and (4) no congenital or acquired heart disease. A long QT interval was recognized when the heart-ratecorrected QT, interval (QTJ was markedly prolonged; 'QTC:> 460 ms'. The QT duration was measured from the onset of the QRS to the end of the T wave, defined as a return to the T-P baseline.Three consecutive cycles were measured and from the three values a mean QT was calculated'141. The QTC was measured by using Bazett's formula'151. A typical ECG tracing of congenital heart block with long QT duration is demonstrated in Fig. 1.
Methods PATIENT POPULATION
From 1963 to 1990,4418 first pacemaker implantations were performed in the Cardiovascular Surgical Clinic. In eight of these patients the association of QT prolongation with congenital complete heart block could be detected (study group). The most important clinical data from these patients are summarized in Table 1. A retrospective familial clinical history was obtained in seven of the cases and no familial long QT syndrome could be detected in any of them. A moderate QT prolongation without any clinical signs was noted in one patient's brother only, while first degree AV block was a Submitted for publication 21 November 1990 and in revised form 2 April 1991. Correspondence Francis Solti, Cardiovascular Surgical Clinic, H-1122 Budapest, Varosmajor Str 68, Hungary. 0195-668X/92/081080 + 04 $03 00/0
ELECTROPHYSIOLOGICAL STUDY
Before pacemaker implantation — to facilitate selection of a suitable pacing mode — an invasive electrophysiological study was performed in each patient of the study group and in 12 patients from the control group. All medication was withdrawn 48 h prior to the study. Informed consent was obtained from all patients. The electrophysiological testing consisted of programmed electrical stimulation of the heart and the recording of endocavital ECG tracings (intracardiac electrograms were recorded from the high right atrium, the His bundle region and the right ventricle). Electrical stimulation of the heart was perfomed by using a programmable digital stimulator (Medtronic 5325) that delivered rectangular impulses lasting 20ms at twice the diastolic threshold. © 1992 The European Society of Cardiology
Long Q T duration with permanent bradycardia 1081
Table 1 Clinical features of patients suffering from congenital total A V block accompanied with long QT duration g 17-7±5-87 5/3
42 ±6-8 485±32 640-48
(range 10-23) (range 38-60) (range 470-500) (range 560-690)
8
i i
Table 2 Clinical characteristics of patients suffering from congenital total A V block with normal QT duration Patients (N) Age (years) Sex (male/female) Heart rate (beats . min~') QT c (ms) QT(ms) Indication for pacemaker implantation Adams-Stokes syncopal attacks Signs of cardiac decompensation (heart enlargement, dyspnoea, exercise intolerance) Accompanying diseases Hypertension Diabetes mellitus
22 23-3 ±6-5 12/10 44 ±7-2 420 ±28 490 ±30
(range 10-30) (range 36-68) (range 390-450) (range 450-520)
3 19 2
1
Figure 1 Congenital AV block associated with QT prolongation demonstrated by surface ECG leads I-III, paper speed 25 mm . s~' and a total AV block with narrow QRS complex. PP = 660 ms, R R = 1400 ms. QT is markedly prolonged (690 ms). The QTC is also prolonged (580 ms)
For inducing ventricular tachycardia single and double ventricular extrastimuli were used. For studying the effect of the different cycle length on the QT duration, ventricular pacing was performed with a driving cycle length ranging from 600-1000 ms.
For statistical comparison of the study group data with that of the control group, the Student's t-test for unpaired data was applied. Patients were followed up after pacemaker implantation for a mean of 28 months (range 6-49 months).
Downloaded from https://academic.oup.com/eurheartj/article-abstract/13/8/1080/435214 by University of West London user on 23 November 2018
Patients (N) Age (years) Sex (male/female) Heart rate (beats. min"1) QT c (ms) QT(ms) Indication for pacemaker implantation Polymorphous ventricular tachycardia attacks with syncope Signs of cardiac decompensation Accompanying diseases Hypertension
1082 F. Solti et al.
550
500
--
450
-
%
o 400
-
t 350
J0O
n
NS
-
i
600
i
700 800 900 Pocing cycle length (mi)
1
1000
Figure 2 The effect of cycle length on QT duration. Asterisks = AV block with >QT, Open squares —AV block without >QT. Values are expressed as mean±SD. | / > < 0 0 1 . J/>
