Dual chamber cardiac pacing in children: Single chamber pacing dual chamber sensing cardiac pacemaker or dual chamber pacing and sensing cardiac pacemaker?

BACKGROUND: Dual chamber pacemakers (single chamber pacing dual chamber sensing cardiac pacemaker (VDD) and dual chamber pacing and sensing cardiac pacemaker (DDD)) are being used frequently in children and adolescents. The aim of this study was to verify the safety and performance of the VDD and DDD pacing systems, and to evaluate the differences between two pacing modes with regard to atrial sensing and tracking functions. METHODS: In this study, we evaluated 14 patients with VDD pacing and 15 patients with DDD pacing between 1994 and 2000. In the patient group with VDD pacing, all had congenital or acquired atrioventricular (AV) block. In the patient group with DDD pacing, 11 had congenital or acquired AV block, three had sinus node dysfunction with AV conduction disturbance and one had idiopathic hypertrophic subaortic stenosis. Twenty-eight devices were implanted in the subpectoral area using the transvenous route. After implantation the atrial tracking capabilities of the pacing systems were analyzed by telemetry, Holter monitoring, and treadmill exercise testing. RESULTS: The mean age of patients in the VDD pacing group was younger. The percentage of congenital heart disease was higher in the DDD pacing group. There was no significant difference regarding fluoroscopy time during implantation and follow-up time between the two groups. During implantation, in the VDD pacing group the mean sensed atrial signal was 3.1 +/- 1.3 mV and this decreased to 1.37 +/- 0.68 mV (P < 0.05) during follow-up. This pattern was also observed in DDD group (3 +/- 2 mV vs 1.9 +/- 1.5 mV, P < 0.05). Although the P wave measurement at implantation did not differ between the two groups, it was significantly higher in the DDD pacing group at the last control. Three patients with VDD pacing were reprogrammed to VVI or single chamber pacing and sensing, rate adaptive cardiac pacemaker because of complete loss of AV synchrony. There was no atrial sensing problem in the DDD pacing group. During the follow-up, one patient with VDD pacing developed diaphragmatic stimulation and required lead revision. In one patient with DDD pacing, venous thrombosis occurred in the right subclavian vein and was treated with thrombolytic therapy. During treadmill exercise testing, in one patient with VDD and one patient with DDD pacing temporary failure of atrial sensing occurred. At 24 h Holter monitoring, intermittent loss of atrial sensing was documented in two patients with VDD pacing. CONCLUSIONS: Dual chamber pacing in children with DDD or VDD pacemakers is a suitable method for bradycardia treatment. Atrial sensing problems may occur in VDD pacemakers. Therefore, DDD pacing mode should be preferred whenever suitable for the patient to maintain the AV synchrony.     

The electrophysiologic effects of propafenone hydrochloride in the neonatal canine

The electrophysiologic effects of the new antiarrhythmic agent, propafenone, were investigated in 10 mongrel canine neonates, ages 5 to 11 days. Utilizing standard His bundle recording and stimulation techniques, assessments of sinus and atrioventricular (AV) node function and atrial, AV nodal, and ventricular refractory periods were performed prior to (control) and after cumulative intravenous doses of 1, 2, and 4 mg/kg of propafenone. Propafenone depressed the spontaneous heart rate and prolonged the postatrial pacing recovery times. AV nodal function was depressed as manifested by Wenckebach periodicity occurring at slower pacing rates, increases in AV nodal conduction time, and increases in AV nodal refractoriness. Atrial and ventricular refractory periods were prolonged significantly in a dose-dependent fashion. Prolongation of the His-Purkinje conduction time occurred at the highest dose. Thus, propafenone exerts a generalized depressant effect on neonatal myocardial conduction and refractoriness which suggests that this agent may be useful in the therapy of atrial and ventricular dysrhythmias in the immature heart.     

Arrhythmias in Children

Arrhythmias in children can be classified according to their effect on central pulse: Fast pulse rate – tachyarrhythmia; Slow pulse rate – bradyarrhythmia; and Absent pulse is pulseless arrest (cardiac arrest). Tachyarrythmia may be narrow complex tachycardia (QRS duration ≤0.08 s): sinus tachycardia (ST), supraventricular tachycardia (SVT), atrial flutter or Wide-complex tachycardia (QRS duration >0.08 s): ventricular tachycardia (VT), SVT with aberrant intraventricular conduction. The choice of therapy depends on the patient’s degree of hemodynamic instability. Attempt vagal stimulation, if patient is stable and if it does not unduly delay chemical or electrical cardioversion. Bradyarrhythmias include: sinus bradycardia, sinus node arrest with atrial, junctional and idioventricular escape rhythms and AV block. The emergency treatment of bradycardia depends on its hemodynamic consequences. If heart rate is <60 beats per minute with poor perfusion despite effective ventilation with oxygen, it may be treated with chest compressions, epinephrine through IV or endotracheal tube. If bradycardia persists or responds only transiently, consider a continuous infusion of epinephrine or isoproterenol and plan for emergency transcutaneous pacing. If bradycardia is due to vagal stimulation or primary A-V block, giving atropine may be beneficial.     

经食道心房调搏测定PR间期延长患儿房室传导功能的研究

目的了解食道心房调搏在房室传导功能检测中的意义。方法对３９例ＰＲ间期延长（研究组）和１４１例ＰＲ间期正常（对照组）患儿房室传导功能进行了经食道心房调搏研究。结果在非房室结双径路和多径路者,研究组的房室传导有效不应期、文氏传导阻滞点及同一刺激频率的ＳＶ间期较对照组为长。但在房室结双径路和多径路者,研究组和对照组文氏传导阻滞点及同一刺激频率的ＳＶ间期以及快径路的有效不应期和功能不应期无显著性差别。结论经食道心房调搏对于房室传导功能的检测有一定的价值     

Atrioventricular nodal function in the immature canine heart [corrected and republished article orginally printed in Pediatr Res 1987 Nov;22(5):616-20

Previous studies have suggested that the atrioventricular nodal functional refractory period in the neonate is equal to or shorter than that of the ventricle, providing little or no protection to the ventricle against rapid atrial rates and allowing closely coupled atrial beats to fall within the ventricular vulnerable period. We evaluated atrioventricular node function in 21 mongrel neonatal puppies, 3-15 days old, and 15 adult dogs utilizing intracardiac His bundle recording and stimulation techniques. The mean atrioventricular nodal functional refractory period (173.1 +/- 20.0 ms) exceeded both the ventricular effective refractory period (139.5 +/- 14.3) and ventricular functional refractory period (163.3 +/- 14.5) in the neonates. Furthermore, the atrioventricular node was the site of limiting antegrade conduction in all neonates. No ventricular arrhythmias were induced by atrial extrastimulation in any of the neonates. The site of conduction delay during atrial extrastimulation was confined to the atrioventricular node in 15/16 neonates (94%) while 1/16 (6%) had combined nodal and infranodal delay. The neonates developed Wenckebach, at significantly faster heart rates than the adults, but both groups developed Wenckebach at approximately twice the resting heart rate. Retrograde conduction was a consistent finding in the neonates. However, antegrade Wenckebach occurred at a significantly faster heart rate than retrograde Wenckebach suggesting different functional properties. Our data suggest that in the neonatal canine, the atrioventricular node functional refractory period is longer than both the ventricular effective refractory period and ventricular functional refractory period. Furthermore, the degree of protection offered by the neonatal atrioventricular node to the ventricle appears to be comparable to that of the adult.     

食管心房调搏术在婴幼儿室上性心动过速中的应用

目的 探讨食管心房调搏术(TEAP)在婴幼儿室上性心动过速(SVT)诊断和治疗中的应用价值.方法　选取43例年龄<2岁的SVT婴幼儿.其中男23例,女20例;年龄(7.59±9.80)个月.采用TEAP检查,随后根据记录食管心电图进行分型诊断,明确为折返性心动过速、房性心动过速、房性扑动后立即进行超速抑制终止心动过速.并对其资料进行回顾性分析.结果　43例SVT婴幼儿经食管电生理检查,心室率为(233.31±46.79)次·min-1.其中29例次SVT中诊断为折返型SVT 23例次,房性动过速3例次,窦性心动过速并Ⅰ度房室传导阻滞(Ⅰ-AVB) 2例次,窦性心动过速1例次,房性扑动14例次.宽QRS心动过速2例,1例为Ⅰ-AVB并室内传导阻滞,另1例经随访确诊为交界性心动过速并室内传导阻滞.经TEAP成功转复率为83% (34/41例).结论　婴幼儿SVT往往伴较快心室率,如不及时救治极易产生不可逆的损害.TEAP的应用有助于婴幼儿SVT的诊断分型,而且其安全快速转复窦性心律的优点在婴幼儿心动过速的抢救中起重要作用.     

Atrial overdrive pacing for conversion of atrial flutter in children

Twenty-three successive patients with 27 different episodes of sustained atrial flutter were treated with atrial pacing for conversion of the tachyarrhythmia; 15 patients with 16 episodes of atrial flutter underwent intracardiac right atrial pacing and eight patients with 11 episodes of atrial flutter were treated with transesophageal atrial pacing. Ten of sixteen episodes (63%) and eight of 11 episodes (73%) were successfully converted using intracardiac and transesophageal techniques, respectively. Mean flutter cycle length for all 27 episodes was 219 ms (mean heart rate 274 beats per minute); successful pacing conversion cycle length (n = 15) was 72% of the flutter cycle length. Hemodynamic, electrophysiologic, and roentgenographic data were not predictive of conversion by either technique. Induction of localized atrial fibrillation or failure to meet critical pacing criteria may explain pacing failures. Based on this experience, a trial of transesophageal atrial pacing for acute conversion of any episode of atrial flutter in children prior to direct current cardioversion is recommended.     

儿童左束支区域起搏六例临床观察

目的探讨儿童左束支区域起搏(LBBAP)的安全性及有效性.方法回顾性分析2019年1月至6月于北京安贞医院小儿心脏科住院采用LBBAP方式行永久心脏起搏器植入术的6例患儿(男1例、女5例)的临床资料、起搏心电图及参数并进行随访.组间比较采用t检验.结果6例患儿年龄9~14岁,体重26~48 kg;三度房室传导阻滞5例,右室心尖起搏术后伴心功能下降1例;1例患儿心功能降低,余5例心功能均正常;QRS波时限(95±13)ms;左心室舒张末径(LVEDD)Z值为1.85±0.65.起搏心电图V1呈右束支传导阻滞样,QRS波时限(111±20)ms,与术前相比,差异无统计学意义(t=-1.610,P>0.05).起搏阈值为(0.85±0.26)V,感知(15.0±4.3)mV,阻抗(717±72)Ω.3例可记录到P电位.起搏钉至左心室激动时间为(56±5)ms,不同输出电压下数值恒定.术后超声提示电极均位于室间隔左心室心内膜下.随访无心肌穿孔、电极脱位等并发症发生,患儿术后3个月阈值、感知及阻抗分别为(0.60±0.09)V、(16.1±3.9)mV、(662±78)Ω.左心室射血分数(LVEF)降低者LBBAP术后3d恢复正常(45%比57%).术后3个月LVEDD Z值降至(1.1±0.3),较术前明显减小(t=2.383,P<0.05).结论LBBAP可实现窄QRS波起搏,接近生理性起搏,起搏参数稳定,可快速、有效地纠正长期心动过缓所致的左心扩大及长期右室心尖起搏所致的心功能低下及心脏扩大.较大年龄儿童行LBBAP近期安全性、有效性好,远期潜在风险有待进一步观察研究.     

Elucidation on sudden death in children with the mucocutaneous lymph node syndrome

Atrial pacing was carried out in six children aged one year to eleven years with the mucocutaneous lymph node syndrome (MCLS) during cardiac catheterization. The cardiac index (CI) was measured before pacing and at pacing rates of 150 and 180/min. The CI increased in cases which did not show any pathological findings on the coronary artery angiograms. Conversely, CI decreased at a pacing rate of 150/min, in the case which showed arterial stenosis. Atrial pacing with measurement of CI may be a good method for detecting and evaluating coronary artery lesions in children with MCLS.     

电学治疗在小儿重症心律失常病例急救中的应用

目的 探讨电学治疗在重症心律失常病例急救中的应用体会。方法16例病情危重的心律失常病例,分别接受食道心房调搏、体外电复律、紧急安装临时起搏器等急救处理。合并基础心脏病者予以相应治疗。结果 食道心房快速刺激成功终止2例房扑及1例房室折返性心动过速的发作,另1例房室折返性心动过速稍后复发。室颤、尖端扭转性室速、房扑病例及2例室速经电复律转为窦性,1例暴发性心肌炎所致室速电复律无效最终死亡。3例完全性房室传导阻滞(CAVB)安装临时起搏器的暴发性心肌炎病例均治愈,其中1例安装永久起搏器。结论 电学治疗是小儿危重心律失常病例急救中有效的治疗手段,但对继发于基础心脏病的病例,应给予相应的综合治疗。     

Temporary Atrial Pacing for Cardiac Output After Pediatric Cardiac Surgery

Pediatric cardiothoracic surgery is often associated with low cardiac output in the postoperative period. This study sought to determine whether increasing heart rate via temporary atrial pacing is beneficial in augmenting cardiac output. Patients younger than 18 years who underwent cardiothoracic surgery and had no perioperative arrhythmias were eligible for the study. Patients not paced postoperatively were atrial paced at a rate of 15 % above the intrinsic sinus rate (not to exceed 170 beats per minute, less for older patients) for 15 min. Patients paced for cardiac output postoperatively had their pacemakers paused for 15 min. Markers of cardiac output were measured before and after the intervention. Of the 60 patients who consented to participate, 30 completed the study. Failure to complete the study was due to tachycardia (n = 13), lack of pacing wires (n = 7), junctional rhythm (n = 4), advanced atrioventricular block (n = 3), and other cause (n = 3). Three patients were paced at baseline. There was no change in arteriovenous oxygen saturation difference, mean arterial blood pressure, central venous pressure, toe temperature, or lactate with atrial pacing. Atrial pacing was associated with a decrease in head and flank near-infrared spectroscopy (p = 0.01 and <0.01 respectively). Secondary analysis found an inverse relationship between mean arterial pressure response to pacing and bypass time. Temporary atrial pacing does not improve cardiac output after pediatric cardiac surgery and may be deleterious. Future research may identify subsets of patients who benefit from this strategy. Practitioners considering this strategy should carefully evaluate each patient’s response to atrial pacing before its implementation.     

食道调搏在儿科房室交界区功能检查中的应用

目的　探讨食道心房调搏测量儿童房室交界区各不应期和传导时间的应用价值 ,评价其传导功能及其特点。方法　对 5 9例正常儿童进行食道调搏 (TEAP)检查 ,测量房室交界区不应期和传导阻滞点。结果　正常儿童房室传导功能由不应期和传导阻滞点具体体现 ,为儿童正常值提供参考 ;相对不应期 (RRP)、功能不应期 (FRP)、文氏点与心率呈显著相关 (P分别为 0 .0 0 0、0 .0 1、0 .0 0 0 ) ,与性别、年龄无关 (P均 >0 .0 5 ) ;而绝对不应期 (ERP)、2∶1阻滞点与性别、年龄、心率均无关 (P均 >0 .0 5 ) ;文氏点与RRP显著相关 (P =0 .0 0 0 ) ;2 :1阻滞点与ERP显著相关 (P =0 .0 15 )。结论　TEAP可评估儿童房室交界区的传导功能 ;RRP与心率有直接关系 ,ERP是评价房室传导功能的主要指标     

Resolution of Plastic Bronchitis with Atrial Pacing in a Patient with Fontan Physiology

We describe a 5-year-old boy with Fontan physiology and a ventricular pacemaker who developed severe plastic bronchitis. Evaluation by cardiac catheterization revealed profoundly altered hemodynamics, which improved with atrial pacing. Following implantation of an atrial pacemaker, which restored atrioventricular (A-V) synchrony, the patients hemodynamics greatly improved and his plastic bronchitis resolved.     

儿童心肌炎经食道心房调搏检查36例报告

经食道心房调搏检查心肌炎患儿36例,结果:SACTc延长11例,cSNRT延长7例,SNRT延长3例;AVERP延长15例,AVFRP延长6例,文氏、2:1阻滞点降低分别为13、14例。SACT延长有5例与AVERP延长并存,AVERP延长者几乎与文氏,2:1阻滞点均降低。房室结功能异常的心电图表现主要为束支传导阻滞,其次为ST及T波改变;窦房结功能异常的心电图表现主要为窦房结传导阻滞。异常电生理患者仅有4例在1～3周内发病,大多在1月以上,最长1～2年,有心脏扩大者均有电生理异常。     

Atrial flutter in infancy: diagnosis, clinical features, and treatment

The clinical features and treatment of atrial flutter in eight infants (four male and four female) less than 2 months of age are presented. Atrial flutter was noted during the first week of life in six of the infants and between 6 and 8 weeks of life in the other two infants. Four of the eight infants had associated structural or functional cardiovascular disease, and in three infants a central venous pressure catheter was present in the atrium at the time atrial flutter was diagnosed. Classic flutter waves were apparent on 12-lead ECGs in only two infants. In six infants, flutter waves were not obvious on standard ECGs, but transesophageal electrogram recordings demonstrated the presence of atrial flutter with second degree atrioventricular block. The atrial cycle length during flutter ranged from 135 to 180 ms (mean 149 ms; mean atrial rate 403 beats per minute); there was a 2:1 ventricular response to atrial flutter. Successful termination of atrial flutter was accomplished using three modes of electrical cardioversion in seven of the eight infants: direct current cardioversion in one, transvenous atrial pacing in one, and transesophageal atrial pacing in five. One asymptomatic infant converted to normal sinus rhythm 24 hours following digoxin administration. One infant had multiple atrial flutter recurrences and required chronic procainamide therapy. In seven of the eight infants, no recurrences have been noted in 6 months to 3 1/2 years of follow-up. These results demonstrate that atrial flutter may be difficult to diagnose in infants with tachycardia unless transesophageal electrogram recording is utilized for evaluation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Emergency Pacing and Subsequent Permanent Pacemaker Implantation in a Premature Infant of 1770 g with a Follow-Up of 6 Years

We report successful emergency pacing followed by permanent pacemaker implantation due to complete block in an otherwise healthy premature infant of 1770 g. Via the umbilical vein a temporary bipolar pacing lead was placed in the right ventricle. The lack of spontaneous improvement warranted implantation of a permanent pacemaker system at the age of 2 weeks. Via a transatrial approach an endocardial unipolar screw-in lead was placed in the right ventricle and connected to a pulse generator implanted subcutaneously. During the follow-up period of 6 years the child has been doing well with his VVI-R pacemaker operating at rates between 80 and 160 pulses/minute at a chronic stimulation threshold below 0.9 V at 0.37 msec.     

Management with a staged approach of the premature hydropic fetus due to complete congenital heart block

The management of the preterm fetus with hydrops due to complete congenital heart block is difficult. The outcome is frequently associated with significant morbidity and mortality. Two fetuses presented at the post menstrual age of 29 and 30 weeks respectively with severe hydrops due to complete heart block. The following staged approach was adopted: (1) enhance fetal lung maturation with maternal corticosteroids and thyroid releasing hormone for 48 h; (2) elective Caesarean section; (3) classical neonatal management consisting of intubation and ventilation, drainage of all cavities with effusions; (4) increase neonatal heart rate by administration of IV isoprenaline, by bipolar trans-oesophageal pacing or epicutaneo-oesophageal pacing; (5) after the regression of the hydrops, start epicardial pacing after implantation of 2 or 3 temporary epicardial 3/0 pacemaker; (6) implantation of a permanent abdominal pacing system with steroid epicardial tip once the threshold exceeds 20 mA or when the baby weighs more than 1500 g. In these patients a permanent pacing system was implanted at the ages of 8 weeks (2045 g) and 4 weeks (1560 g) respectively. No major complications occurred; the cardiac outcome with 37 and 34 months of follow up is excellent. Conclusion This proposed staged approach with tem‐porary epicardial leads can improve the outcome of hydropic fetuses due to complete congenital AV block. Received: 10 March 1996 and in revised form: 26 July 1996 / Accepted, 6 August 1996     

The influence of age on cardiac refractory periods in man.

As age is a determinant of cardiac refractory periods, this communication describes changes of refractory periods in an age continuum of infants, children and adults, 7 months through 77 years. Seventy patients with evidence of normal A-V conduction on scalar electrocardiogram were included. The patients were divided into six age groups: less than 2 years, 3-5 years, 6-10 years, 11-15 years, 16-30 years, and greater than 30 years. Extrastimulus technique was used to determine refractory periods in sinus rhythm or at longest cycle length assuring atrial capture, then at shorter cycle lengths. Cycle lengths (CL) for each age group were divided into ranges: CL1, 1,000-600 msec; CL2, 599-460 msec; CL3, less than 459 msec. Refractory periods at the three CL's within each age group were determined. Full recovery times of the A-V node within groups of children were determined. Statistical significance of the data was found by analysis of variance. The younger group tended to have shorter values than the older groups (F less than 0.05-0.001).     

Paroxysmal Atrioventricular Block in Young Patients<Superscript>1</Superscript>

We describe 17 patients (8 girls, and 9 boys), aged 9.6 ± 5.7 years, with paroxysmal atrioventricular block (PAVB), a condition rarely described in children. Holter monitoring documented the PAVB in 15 patients, and tilt test was performed in 4 patients (positive in 1). The electrocardiograph (ECG) was normal in 7 patients. Two patients had acquired and 11 patients had congenital heart disease (CHD). Syncope or presyncope were present in 7 patients. A normal ECG was significantly more frequent in symptomatic patients. Pauses were significantly longer in girls and in children <5 years. PAVB was recorded only during nocturnal hours in 6 patients and throughout the day in the others. The sinus rate decreased during PAVB in 6 patients and increased in 4 (generally younger girls with symptoms). Permanent pacemakers were implanted in 13 patients, including 7 asymptomatic patients with CHD and severe bradycardia. During follow-up (3.7 ± 2.5 years), 1 patient developed complete AVB. Although PAVB was still present in 91% of paced patients, symptoms did not recur because pacing prevented the pauses. In conclusion, PAVB is a rare arrhythmia. Autonomic nervous system dysfunction seems to play an etiological role and permanent pacing was an effective treatment.¹Preliminary results of this study presented at the 15^th International Congress, The New Frontiers of Arrhythmias, Marilleva, Italy, 2002     

Evolution of Heart Rate Control After Transplantation: Conduction Versus Autonomic Innervation

In cardiac transplantation, the donor organ is not initially innervated and demonstrates decreased heart rate variability (HRV). However, HRV may improve after several months. The mechanism for HRV improvement has not been elucidated; autonomic reinnervation of the donor heart has been proposed. The role of atrioatrial conduction from recipient to donor organ has not been evaluated. We prospectively evaluated cardiac transplant patients with a limited electrophysiology study at the time of their surveillance biopsies. Recordings were made of recipient and donor signals, observing conduction properties between recipient and donor atria. Holter recordings were analyzed and HRV was determined using spectral analysis techniques, recording mean RR interval, low-frequency power (LF), high-frequency power (HF), and the LF/HF ratio. These were compared to published norms. From November 1999 to May 2000, 21 patients (6 female) who underwent cardiac transplantation participated at a median age of 101 months (range, 4.1–217 months). Time posttransplant ranged from 26 days to 71 months. Holter data were available for 20 patients and demonstrated dissociated P waves in 13 (65%). The mean heart rate on Holter was 111 beats per minute (bpm) (range, 85–161 bpm). We were able to record distinct recipient atrial signals in 16 of 21 (76%) patients. The average recipient tissue heart rate was 55% that of the donor heart rate. We documented atrioatrial association in only 1 patient. HRV did not reach normal values for most patients and did not increase with time posttransplantation. The LF values were in the normal range for most patients, whereas 3 patients had normal HF values and 2 patients had values just below normal. Recipients of heart transplantation have a predominantly sympathetic influence of HRV. These preliminary data suggest that atrioatrial conduction does not play a role in reestablishing normal heart rate control following pediatric cardiac transplantation.