Interventions in the diagnosis and adoption of pacemaker therapy in sinus node dysfunction patients: Results from the IMPROVE Brady study

Aims: IMPROVE Brady assessed whether a process improvement intervention could increase adoption of guideline-based therapy in sinus node dysfunction (SND) patients. Methods: /Results: IMPROVE Brady was a sequential, prospective, quality improvement initiative conducted in India and Bangladesh. Patients with symptomatic bradycardia were enrolled. In Phase I, physicians assessed and treated patients per standard care. Phase II began after implementing educational materials for physicians and patients. Primary objectives were to evaluate the impact of the intervention on SND diagnosis and pacemaker (PPM) implant. SF-12 quality of life (QoL) and Zarit burden surveys were collected pre- and post-PPM implant. A total of 978 patients were enrolled (57.7 ± 14.8 years, 75% male), 508 in Phase I and 470 in Phase II. The diagnosis of SND and implantation of PPM increased significantly from Phase I to Phase II (72% vs. 87%, P < 0.001 and 17% vs. 32%, P < 0.001, respectively). Pacemaker implantation was not feasible in 41% of patients due to insurance/cost barriers which was unaltered by the intervention. Both patient QoL and caregiver burden improved at 6-months post-PPM implant (P < 0.001). Conclusions: A process improvement initiative conducted at centers across India and Bangladesh significantly increased the diagnosis of SND and subsequent treatment with PPM therapy despite the socio-economic constraints.

Disfunción del nódulo sinusal asociado a estenosis severa proximal de la arteria coronaria derecha y vasoespasmo coronario

RESUMEN La disfunción del nódulo sinusal (DNS) es generalmente secundaria a la senescencia del nodo sinusal y del miocardio auricular circundante. Estamos presentando un paciente de 59 años de edad, hipertenso sin tratamiento y con antecedente de síncope en dos oportunidades en los últimos 4 meses. Ingresa debido a un flutter auricular con conducción auriculoventricular 1:1 con una frecuencia cardiaca de 280 lat/min que cede con goteo de amiodarona. Un Holter de 24 horas demostró un ritmo sinusal predominante, episodios paroxísticos de fibrilación auricular con respuesta ventricular alta, bradicardia sinusal de 47 lat/min. Se realizó el diagnóstico de disfunción del nódulo sinusal, Rubenstein tipo III (Síndrome Bradicardia-Taquicardia). Una coronariografía constató una estenosis del 80% en segmento proximal de la arteria coronaria derecha con componente espástico. La arteria del nódulo sinusal emerge del segmento proximal de la coronaria derecha. Se realizó una angioplastia exitosa con stent medicado. Otro estudio Holter de 24 horas de control pos-angioplastia registró nuevamente episodios paroxísticos de fibrilación auricular con respuesta ventricular alta y episodios de pausas de hasta 3.100 milisegundos por lo que se implantó un marcapasos bicameral. A pesar del restablecimiento de un flujo sanguíneo adecuado a la arteria del nódulo sinusal con la angioplastia de la coronaria derecha no se obtuvo una mejoría de la disfunción del nódulo sinusal.

ABSTRACT Sinus node dysfunction (SND) is generally secondary to senescence of the sinus node and the surrounding atrial myocardium. We are presenting a 59-year-old patient, hypertensive without treatment and with a history of syncope on two occasions in the last 4 months. He was admitted due to a 1: 1 atrioventricular conduction atrial flutter with a heart rate of 280 beats/min that subsides with an amiodarone drip. A 24-hour Holter monitor showed predominant sinus rhythm, paroxysmal episodes of atrial fibrillation with high ventricular response, sinus bradycardia of 47 beats/min. The diagnosis of sinus node dysfunction, Rubenstein type III (Bradycardia-Tachycardia Syndrome) was made. A coronary angiography confirmed an 80% stenosis in the proximal segment of the right coronary artery with a spastic component. The sinus node artery emerges from the proximal segment of the right coronary artery. A successful angioplasty was performed with a medicated stent. Another 24-hour Holter study of post-angioplasty control again recorded paroxysmal atrial fibrillation with high ventricular response episodes and pause episodes of up to 3,100 milliseconds, for which a dual-chamber pacemaker was implanted. Despite the restoration of adequate blood flow to the sinus node artery with right coronary angioplasty, no improvement in sinus node dysfunction was obtained.

El nodo sinusal normal: Lo que ahora sabemos / The normal sinus node: What we know now

RESUMEN El nodo sinusal constituye el marcapasos fisiológico del corazón. Diferentes estados fisiopatológicos conducen a una reducción de su función, lo que es llamado en la clínica, disfunción sinusal. Sin embargo, para la mejor comprensión de su estado de enfermedad se requiere dilucidar cómo opera en condiciones normales. Las nuevas evidencias señalan que el automatismo del nodo sinusal se produce por la interacción del reloj de membrana y el reloj de calcio, lo que le confiere un fuerte carácter que lo protege contra fallas de funcionamiento. Se presentan las evidencias actuales sobre la sincronía celular dentro del nodo sinusal, así como la forma de propagación eléctrica y el acoplamiento fuente-sumidero. Además, se describen recientes hallazgos anatómicos e histológicos.

ABSTRACT The sinus node is the physiological pacemaker of the heart. Different pathophysiological conditions lead to a reduction of its function, which is clinically called sinus dysfunction. However, for a better understanding of its disease state, it is necessary to elucidate how it works under normal conditions. New evidences indicate that the automatism of the sinus node is produced by the interaction of the membrane clock and the calcium clock, which gives it a strong character that protects it against malfunctions. Current evidences on cell synchrony within the sinus node are presented, as well as the form of electrical propagation and the source-sink coupling. In addition, recent anatomical and histological findings are described.

Efecto del cilostazol en la enfermedad del nodo sinusal / Cilostazol and sick sinus syndrome

Resumen Se presenta el caso de una paciente de 60 años con enfermedad del nodo sinusal (ENS), sintomática con mareos y ángor, con electrocardiograma que evidenciaba episodios de pausas sinusales con escapes nodales. Durante la internación, a la espera de colocación de marcapaso definitivo, se indicó cilostazol (100 mg cada 12 h vía oral), observando a las 48 horas del inicio un incremento en la frecuencia cardíaca y la desaparición de las pausas sinusales en Holter de 24 horas. Nuestro objetivo ha sido demostrar que el cilostazol puede ser útil en pacientes con ENS, aunque es necesario evaluar los efectos cronotrópicos a largo plazo de este tratamiento.

Abstract Here we present the case of a 60-year-old patient with sinus node disease (NSS), symptomatic with dizziness and angor. The electrocardiogram showed episodes of sinus pauses with nodal escapes. During hospitalization, pending the placement of a definitive pacemaker, cilostazol (100 mg every 12 hours orally) was indicated, observing an increase in heart rate 48 hours after starting the medication, and the disappearance of sinus pauses in the 24 hours Holter. Our objective has been to show that cilostazol can be useful in patients with SNN, although long-term chronotropic effects of this treatment has yet to be evaluated.

Caracterización clínico epidemiológica de pacientes con implante de marcapasos permanente / Clinical and epidemiological characterization of patients with permanent pacemaker implants

RESUMEN Introducción: el implante de marcapasos permanente sigue una tendencia al alza en los últimos años. El aumento de la esperanza de vida implica una mayor incidencia de enfermedades degenerativas, que implican la mayoría de los implantes. Objetivo: caracterizar clínica y epidemiológicamente a los pacientes con implantación de marcapasos permanente en el servicio de Cardiología del Hospital General Docente o Clínico Quirúrgico Docente "Celia Sánchez Manduley", de enero 2017 - diciembre 2018. Métodos: se realizó un estudio descriptivo, transversal y retrospectivo en pacientes a los cuales se les realizó implantación de marcapasos. La población en estudio la constituyeron los 132 pacientes sometidos al proceder. Se calculó la frecuencia absoluta, media aritmética con desviación estándar y cálculo porcentual. Resultados: el grupo etario más afectado fue el de 81 - 90 (38,6 %) y el sexo masculino (52,2 %). Se realizó por vena cefálica el 52,2 %, en tiempo quirúrgico predominante de una a dos horas (60,5 %). Prevalecieron los pacientes con síncope, (58,3 %). El 31,8% de las indicaciones fue por bloqueo auriculoventricular de tercer grado. La complicación más frecuente fue la infección (52,2 %). Conclusiones: la implantación de marcapasos fue más frecuente en hombres y en pacientes con edad entre 81 y 90 años. La vía más empleada fue la vena cefálica. Se emplearon de una a dos horas en el proceder. La mayoría de los pacientes acudieron por síncope. La principal indicación fue el bloqueo auriculoventricular de tercer grado. La infección fue la más frecuente de las complicaciones.

ABSTRACT Introduction: the implantation of permanent pacemakers follows an upward trend in recent years. The increase in life expectancy implies a higher incidence of degenerative diseases, which cause most implants. Objective: to characterize clinical and epidemiologically patients with permanent pacemaker implantation in Cardiology Service at Celia Sánchez Manduley Hospital from January 2017 - December 2018. Methods: a descriptive, cross-sectional and retrospective study in patients with permanent pacemakers implantations in the Cardiology Service at Celia Sánchez Manduley Hospital from January 2017 to December 2018. The study population comprised 132 patients who underwent this procedure. Absolute frequency, arithmetic mean with standard deviation and percentage calculation were performed. Results: the most affected age group was 81-90 (38,6 %) and male sex (52,2 %). The most used route was cephalic vein dissection (52,2 %) and the predominant surgical time was 1 to 2 hours in 60,5 %. There was a prevalence of patients with syncope (58,3%). Thirty-one percent of the indications were for third-degree atrioventricular block. The most frequent complication was infection. Conclusions: permanent pacemakers was more frequent implanted in men and in patients between 81 and 90 years old. The most used route was the cephalic vein. The procedure lasted one to two hours. The most frequent cause for admission was syncope. The main indication was in the third degree atrioventricular block. Infection was the most frequent of the complications.

Permanent Pacemaker Implantations after Catheter Ablation in Patients with Atrial Fibrillation Associated with Underlying Sinus Node Dysfunction

BACKGROUND AND OBJECTIVES: The objective of this study was to evaluate the long-term clinical outcomes and the incidence of permanent pacemaker implantation after catheter ablation in patients with of atrial fibrillation (AF) and sinus node dysfunction (SND).METHODS: Among 3,068 total consecutive patients who underwent AF catheter ablation (AFCA), this study included 222 (9.5%; men 53.2%, 63.7±9.2 years of age, 81.5% paroxysmal AF) with underlying SND and a regular rhythm follow-up. We analyzed the rhythm outcomes, changes in the mean heart rate or heart rate variability, and permanent pacemaker implantation rate.RESULTS: During 47.5±28.8 months of follow-up, 25 (11.3%) patients received pacemaker implantations due to symptomatic SND. More than half (56.0%, 14/25) underwent a pacemaker implantation within 3 months of the AFCA, and the annual pacemaker implantation rate was 2.0% afterwards. Both the early (68.0% vs. 31.0%, p<0.001) and clinical AF recurrence (68.0% vs. 32.5%, p=0.001) rates and continuous antiarrhythmic drug use after 3 months (44.0% vs. 24.4%, p=0.036) were significantly higher in patients requiring pacemaker implantations than those that did not. An anterior linear ablation (odds ratio [OR], 9.37 [3.03–28.9]; p<0.001) and the E/Em (OR, 1.15 [1.02–1.28]; p=0.018) were independently associated with permanent pacemaker implantations after AFCA in patients with AF and SND.CONCLUSIONS: After AFCA in patients with AF and SND, 1 of 9 patients needed a pacemaker implantation and half needed implantations within 3 months. The AF recurrence rate was significantly higher in those who required pacemaker implantations after the AFCA.

Oclusión total de la arteria coronaria derecha y disfunción de la arteria del nodo sinoatrial / A total occlusion of the right coronary artery and a dysfunction of the sinoatrial node artery

Resumen La arteria del nodo sinoatrial irriga al marcapasos principal del corazón y su oclusión o lesión puede generar arritmias. Se reportó un infarto de miocardio inferior, el cual presentó oclusión total trombótica proximal de la coronaria derecha, y presentó desde extrasístoles atriales hasta bloqueo atrioventricular. Se describieron las 6 rutas que puede seguir la arteria del nodo sinoatrial y las distintas manifestaciones clínicas que puede tener su oclusión o daño. Se deben realizar estudios de prevalencia para conocer la distribución de esta arteria en la población mexicana, y poder predecir con mayor probabilidad los trastornos del ritmo.

Abstract The sinus node artery irrigates the main pacemaker of the heart and its occlusion or damage can generate arrhythmias. We reported the case of a patient that had an inferior myocardial infarction due to total thrombotic occlusion of the proximal right coronary artery, atrial premature beats and an atrioventricular block. We described the 6 routes that the sinus node artery can follow and the different clinical manifestations that can be observed if occluded. Prevalence studies should be conducted to determine the distribution of this artery in the Mexican population, and to be able to predict rhythm disorders with a higher probability.

Changes in expression of Cx45 and Cx40 in sinoatrial node during dexmedetomidine-induced sinus bradycardia in rats / 中华麻醉学杂志

Objective To evaluate the changes in the expression of Cx45 and Cx40 in the sinoatrial node during dexmedetomidine-induced sinus bradycardia in rats. Methods Forty healthy Sprague-Dawley rats, weighing 250-300 g, were divided into 5 groups ( n=8 each) using a random number table method:control group ( group C) , low-dose dexmedetomidine group ( group D1 ) , high-dose dexmedetomidine group ( group D2 ) , low-dose dexmedetomidine plus atropin group ( group D1 A) , and high-dose dexmedetomidine plus atropin group (group D2A). Normal saline was intravenously infused in group C. Dexmedetomidine was intravenously infused for 10 min as a loading dose of 20 and 120 μg∕kg, followed by an infusion of 10 and 60 μg·kg-1 ·h-1 for 110 min in D1 and D2 groups, respectively. In D1 A and D2 A groups, dexme-detomidine was correspondingly given according to the method previously described in D1 and D2 groups, and in addition atropin 0. 5 mg was intravenously injected at the end of infusing the loading dose of dexme-detomidine. Heart rate ( HR ) , mean arterial pressure ( MAP ) and SpO2 were recorded before giving dexmedetomidine and at 10, 60 and 120 min after giving dexmedetomidine, and the development of brady-cardia was recorded. The sinoatrial node tissues were obtained at the end of administration for determination of the expression of Cx45 and Cx40 protein and mRNA by Western blot and real-time polymerase chain reac-tion, respectively. Results The incidence of bradycardia was 100％ in D1 and D2 groups and 0 after using atropin in D1 A and D2 A groups. Compared with group C, HR and MAP were significantly decreased in the other four groups, the expression of Cx45 protein and mRNA was up-regulated, and the expression of Cx40 protein and mRNA was down-regulated in D1 and D2 groups (P<0. 05), and no significant change was found in the expression of Cx45 and Cx40 protein and mRNA in D1A and D2A groups (P>0. 05). Com-pared with group D1 , HR and MAP were significantly increased, the expression of Cx45 protein and mRNA was down-regulated, and the expression of Cx40 protein and mRNA was up-regulated in group D1 A ( P<0. 05) . Compared with group D2 , HR and MAP were significantly increased, the expression of Cx45 pro-tein and mRNA was down-regulated, and the expression of Cx40 protein and mRNA was up-regulated in group D2 A ( P<0. 05) . Conclusion The mechanism by which dexmedetomidine induces sinus bradycardia may be related to up-regulated expression of Cx45 and down-regulated expression of Cx40, and the auto-nomic nervous activity is involved in dexmedetomidine-induced regulation of Cx45 and Cx40 expression in rats.

Expression changes of cardiac sinus node Cx45,Cx31.9 on sinus bradycardia model caused by dexmedetomidine in rabbit / 临床麻醉学杂志

Objective To investigate the changes of cardiac sinus node connexin 45 (Cx45), connexin 31.9(Cx31.9) of gap junction in rabbits'' sinus bradycardia model caused by dexmedetomidine, and to discuss whether the negative frequency and negative conduction caused by Dexmedetomidine are related to the expression changes of connexin.Methods Forty-eight healthy adult New Zealand rabbits were divided into three groups (n=16).Sinus bradycardia rabbits were prepared by intravenous injecting Dexmedetomidine through ear vein.After rabbits were anesthetized by sodium pentobarbital, basic procedures were quickly completed in order to monitor MAP and ECG.Rabbits in group C were injected with normal saline.Rabbits in group D1 were injected a loading dose of dexmedetomidine 10 μg/kg for 10 min, and then continuously pumped 5 μg·kg-1·h-1 for 50 min.Rabbits in group D2 were pumped a loading dose of dexmedetomidine 60 μg/kg for 10 min, and then continuously pumped 30 μg·kg-1·h-1 for 50 min.After observation hearts were quickly removed and sinus node tissue was dissected.The average optical density of sinus node Cx45, Cx31.9 were detected by immunohistochemistry, and the genes expression were detected by real-time quantitative.Results Cx45 gene expression of group D2 showed remarkable increase than groups C and D1(P<0.05), there were no significant differences between groups D1 and C, Cx45 average optical density change were consistent with the gene expression.Cx31.9 gene expression of group D1 showed a more remarkable increase than group C(P<0.05), there were no significant differences between groups D2 and C,D1 and D2, Cx31.9 average optical density changes were consistent with the gene expression.Conclusion Dexmedetomidine increases the expression of low electrical conductivity Cx45, Cx31.9 of gap junction on rabbits'' sinus node, which is one of the possibly reasons that slow down cardiac conduction velocity in sinus node.

P wave

The electrical impulses of atrium arise from the sinus node, subsequently pass through the right and left atrium, and finally arrive at the atrioventricular node. The P wave is the summation of the electrical current generated by depolarization due to its passage through the atrial conduction pathway. It provides many clinical clues that may be useful for diagnosis of atrial, ventricular, or valvular heart diseases. This review article briefly describes the clinical implications, mechanism of genesis, and normal and pathologic features of the P wave.

Expression of fibronectin protein levels in sinoatrial node tissues of hearts following electrocution / 局解手术学杂志

Objective To study the protein levels of fibronectin (Fn) in the sinoatrial node tissues of hearts caused by electric shock death ,and to provide a new theoretical basis for the diagnosis of electric shock death and the identification of death time.MethodsUsing immunohistochemical technique(S-P method) to detect protein levels of 15 cases of human sinoatrial node following electrocution(human experimental group),15 cases of human sinoatrial node with severe traumatic cerebral injury(human control group),35 cases of rabbit sinoatrial node following electrocution(rabbit experimental group ,divided into7 groups according to different sampling time: 0 h ,1 h ,3 h ,6 h ,12 h,24 h.48 h),and 35 cases of rabbit sinoatrial node with broken neck executed(rabbit control group ,divided int0 7 groups according to different sampling time :0 h,1 h.3 h,6 h.12 h.24 h,48 h).ResultsFn positive expression rate in human experimental group was 100% while it was 6.67% in the human control group,and the differences were statistically significant (P < 0.01 ).The Fn expression can be seen after electric shock immediately in the rabbit experimental group,and there was statistical difference compared with the rabbit control group (P < 0.05).Distribution of Fn expression became more and more widely after 3 hours t0 12 hours in the rabbit experimental group ,and there was significant difference compared with the rabbit control group(P < 0.01).The Fn expression began to decrease 24 hours after electrocution,ancl it still had statistical significance 48 hours after electrocution compared with the rabbit control group (P < 0.05).Conclusion Electric shocks significantly enhanced the expression of Fn protein levels in the sinoatrial node tissues , and optical density of Fn positive expression has a regularity change along with the extended time of death.These results could provide a theoretical reference basis for forensic diagnosis of electrocution and identification of death time.

Diagnostic value of dynamic electrocardiogram combined esophageal electrophysiological examination ;for sick sinus syndrome / 心血管康复医学杂志

Objective:To explore diagnostic value of dynamic electrocardiogram (DCG) combined esophageal electro‐physiological examination (EEE) for sick sinus syndrome (SSS) .Methods :A total of 74 cases suspecting SSS ,who presented 24h mean heart rate <55 beats/min in DCG ,were selected .After DCG examination ,all subjects received EEE . Diagnostic value of single and combined examinations wereexplored .Results:Compared withthe SSS positive rate of single DCG and single EEE(87.8% ,86.5% ) ,theSSS positive rate ofDCG combined EEE(97.3% ) was sig‐nificantly rose ,P<0.05 both .Conclusion:Dynamic electrocardiogram combined esophageal electrophysiological ex‐amination can evaluate sinus node function from different angles ,which can significantlyincrease SSS diagnose rat .

Sinus Node Dysfunction with Pulmonary Edema Associated with Hyponatremia / 대한내과학회지

Hyponatremia is the most common electrolyte abnormality in hospitalized patients and often presents no symptoms. The association between sinus node dysfunction and hyponatremia has rarely been reported. We describe a 77-year-old woman who developed reversible sinus node dysfunction accompanied by pulmonary edema that was associated with hyponatremia.

Effects of dexmedetomidine on rabbit sinus node and atrioventricular node / 临床麻醉学杂志

Objective To investigate the effects of different doses of dexmedetomidine(Dex) on rabbit sinus node and atrioventricular node.Methods A total of 24 healthy male rabbits weighing 1.5-2.8 kg,were divided into 3 groups randomly according to random number table (n =8).Group C (control),critical dosage of Dex causing sinus bradycardia D1 (loading dose of Dex was 10 μg/kg, continual pumping dose was 5 μg · kg-1 · h-1 ),six times of critical dosage of Dex causing sinus bradycardia D2 (loading dose of Dex was 60 μg/kg,continual pumping dose was 30 μg·kg-1 ·h-1 ). Rabbits were anesthetized,the right femoral artery was separated and catheterized followed by real-time monitoring of arterial blood pressure.Right external jugular vein was searched and separated,bi-polar stimulating electrode were inserted to the junction of superior vena cava and right atrium,the index of sinus node and atrioventricular node were observed by means of programmed stimulation.Si-nus node recovery time (SNRT),corrected sinus node recovery time (CSNRT),total recovery time (TRT),and atrioventricular node 2∶1 point were recorded before Dex infusion (T0 ),1 5-20 min after infusion of Dex (T1 )and 50-60 min after perfusion of Dex (T2 ).Results SNRT,CSNRT,TRT and 2∶1 point had no statistical significance.Compared with T0 ,SNRT,CSNRT and CSNRT were signifi-cantly prolonged at T1 and T2 .2∶1 point in group D1 and D2 was shortened obviously at T1 than that at T2 (P <0.05).SNRT,CSNRT and TRT of group D1 at T2 were significantly prolonged,2∶1 piont was shortened compared with T1 (P <0.05).SNRT,CSNRT and TRT of group D1 and D2 were pro-longed both at T1 and T2 than those of group C.2∶1 point was shortened in group D1 and D2 at T1 than that in group C (P <0.05).Compared with group D1,SNRT,CSNRT and TRT of group D2 at T1 and T2 were prolonged,2∶1 point was shortened obviously (P <0.05).Conclusion Load capacity of 10 μg/kg Dex apparently inhibits the function of rabbit sinus node and atrioventricular node,which is partially recovered within a short time (≤ 1 h).The inhibiting effect is more continously and re-markably in load capacity of 60 μg/kg Dex.

Protective effects of kaempferol against cardiac sinus node dysfunction via CaMKII deoxidization / 대한해부학회지

Kaempferol exerts cardioprotective actions through incompletely understood mechanisms. This study investigated the molecular mechanisms underlying the cardioprotective effects of kaempferol in sinus node dysfunction (SND) heart. Here, we demonstrate that angiotensin II (Ang II) infusion causes SND through oxidized calmodulin kinase II (CaMKII). In contrast to this, kaempferol protects sinus node against Ang II-induced SND. Ang II evoked apoptosis with caspase-3 activation in sinus nodal cells. However, kaempferol lowered the CaMKII oxidization and the sinus nodal cell death. To block the CaMKII oxidization, gene of p47phox, a cytosolic subunit of NADPH oxidase, was deleted using Cas9 KO plasmid. In the absence of p47phox, sinus nodal cells were highly resistance to Ang II-induced apoptosis, suggesting that oxidized-CaMKII contributed to sinus nodal cell death. In Langendorff heart from Ang II infused mice, kaempferol preserved normal impulse formation at right atrium. These data suggested that kaempferol protects sinus node via inhibition of CaMKII oxidization and may be useful for preventing SND in high risk patients.

The comparison of catheter ablation and permanent pacing on patients with paroxysmal atrial fibrillation related tachycardia-bradycardia syndrome / 中国介入心脏病学杂志

Objective To evaluate the outcome of AF ablation in patients with paroxysmal atrial fibrillation (AF) related tachycardia-bradycardia syndrome. Methods Fifty consecutive patients with paroxysmal AF and prolonged symptomatic sinus pauses on termination of AF referred to our hospital for ablation were evaluated (ABL group). In another 61 patients, paroxysmal AF was treated with anti-arrhythmic drug and a pacemaker was implanted due to AF related tachycardia-bradycardia syndrome. These patients were used as control (PM group). Results A total of 50 patients in the ABL group fulfilled Class I indication for pacemaker implantation at baseline but they actually underwent AF ablation. Re-evaluation at the end of follow-up showed that 47 (94%) patients no longer needed a pacemaker (Class III indication) because of free from AF with no recurrences of pre-syncopal or syncopal events or documented sinus pauses after the last procedure. More patients in the PM group were on AADs (PM 42.6%, ABL 6.0%, P < 0.001) while sinus rhythm maintenance at the end of follow-up was remarkably higher in the ABL group (82.0%vs. 21.3%in PM group, P < 0.001). The total rates of cardiac related re-hospitalization was not significantly different between the two groups, but hospitalizations caused by tachyarrhythmia was significantly higher in the PM group (PM group 14.8%, ABL group 2.0%, P=0.020).The embolic events, heart failure and death rate were not significantly different between the two groups. Conclusions In patients with paroxysmal AF related tachycardia-bradycardia syndrome, AF ablation seems to be superior to a strategy of pacing plus AAD. Pacemaker implantation can be waived in the majority of patients after a successful ablation.

Sinus Node Paucity in Hyperekplexia.

We report a newborn with hyperekplexia and uncontrolled tonic spasms which did not respond to intravenous phenobarbitone and phenytoin, and midazolam infusion. Serum biochemistry, electrocardiography, electroencephalography, lumbar puncture and neuroimaging were normal. Continous cardiac monitoring revealed that tonic spasm episodes were accompanied by sinus node paucity and severe bradycardia. Duration and number of tonic spasm episodes decreased with clonazepam therapy, and she was discharged. At 4 months of age sudden infant death occured. Sudden infant death could be related to the paucity of sinus node. Cardiac pacemaker implantation should be considered even if the medical treatment is successful.

Long-Term Outcome of Single-Chamber Atrial Pacing Compared with Dual-Chamber Pacing in Patients with Sinus-Node Dysfunction and Intact Atrioventricular Node Conduction

PURPOSE: The optimal pacing mode with either single chamber atrial pacemaker (AAI or AAIR) or dual chamber pacemaker (DDD or DDDR) is still not clear in sinus-node dysfunction (SND) and intact atrioventricular (AV) conduction. MATERIALS AND METHODS: Patients who were implanted with permanent pacemaker using AAI(R) (n = 73) or DDD(R) (n = 113) were compared. RESULTS: The baseline characteristics were comparable between the two groups, with a mean follow-up duration of 69 months. The incidence of death did not show statistical difference. However, the incidence of hospitalization for congestive heart failure (CHF) was significantly lower in the AAI(R) group (0%) than the DDD(R) group (8.8%, p = 0.03). Also, atrial fibrillation (AF) was found in 2.8% in the AAI(R) group, which was statistically different from 15.2% of patients in the DDD(R) group (p = 0.01). Four patients (5.5%) with AAI(R) developed AV block, and subsequently switched to DDD(R) pacing. The risk of AF was lower in the patients implanted with AAI(R) than those with DDD(R) [hazard ratio (HR), 0.84; 95% confidence interval, 0.72 to 0.97, p = 0.02]. CONCLUSION: In patients with SND and intact AV conduction, AAI(R) pacing can achieve a better clinical outcome in terms of occurrence of CHF and AF than DDD(R) pacing. These findings support AAI(R) pacing as the preferred pacing mode in patients with SND and intact AV conduction.

A case of sinus node dysfunction and atrial tachycardia after the excision of a left atrial myxoma / 대한내과학회지

Atrial myxoma is the most common primary cardiac tumor, and surgical removal is the treatment of choice. Atrial flutter-fibrillation is common after the surgical excision of such tumors, whereas sinus node dysfunction is a rare complication. We detected postoperative sinus node dysfunction and atrial tachycardia after the excision of a left atrial myxoma in a 63-year-old woman. The patient underwent the implantation of a permanent pacemaker two weeks after the operation. The patient underwent successful catheter ablation of macroreentrant right atrial tachycardia 16 months after the operation with no recurrence of atrial tachycardia over the next four months.

Pacientes chagásicos crônicos portadores de disfunção do nódulo sinusal: a presença de anticorpos IgG com ação agonista muscarínica independe da disfunção ventricular esquerda? / Chronic Chagas disease patients with sinus node dysfunction: is the presence of IgG antibodies with muscarinic agonist action independent of left ventricular dysfunction?

Estudos mostram que anticorpos IgG agonistas muscarínicos, de pacientes chagásicos, alteram a atividade elétrica de células cardíacas in vitro. Outros consideram sua presença, e a da síndrome do nódulo sinusal, conseqüências da lesão cardíaca progressiva. Objetivou-se avaliar a relação entre os anticorpos e as disfunções nodal e ventricular esquerda, em 65 pacientes chagásicos crônicos divididos em grupo I, composto de 31 pacientes portadores da síndrome do nódulo sinusal, e grupo II, de não portadores. A análise dos dados, pelo modelo log linear, mostrou uma interdependência entre a disfunção do nódulo sinusal e os anticorpos (p=0,0021) e entre a disfunção nodal e a ventricular (p=0,0005), mas não houve relação entre esta última e os anticorpos. Idade e sexo não tiveram influência sobre as outras variáveis. Chagásicos crônicos com a síndrome do nódulo sinusal têm maior prevalência de anticorpos agonistas muscarínicos, independentemente da presença de disfunção miocárdica.

Studies have shown that muscarinic agonist IgG antibodies from Chagas disease patients alter the electrical activity of cardiac cells in vitro. Others have considered their presence, along with sinus node dysfunction, to be consequences of progressive cardiac lesions. The aim of this study was to evaluate the relationship between these antibodies and sinus node and left ventricular dysfunction in 65 chronic Chagas disease patients. These patients were divided into group I, composed of 31 patients with sinus node dysfunction, and group II, composed of the patients without this syndrome. Data analysis using the log linear model showed interdependence between sinus node dysfunction and the antibodies (p = 0.0021) and between nodal and ventricular dysfunction (p = 0.0005). However, no relationship was found between the antibodies and ventricular function. Age and sex did not influence any other variables. The chronic Chagas disease patients with sinus node dysfunction had higher prevalence of muscarinic agonist antibodies, independent of the presence of myocardial dysfunction.