Conceptos actuales sobre la clasificación clínica y alteraciones electrofisiológicas en la disfunción del nódulo sinusal / Current concepts about the clinical classification and electrophysiological alterations in the sinus node dysfunction

La disfunción del nódulo sinusal (DNS) es generalmente secundaria a la senescencia del nodo sinusal y del miocardio auricular circundante. Los pacientes con este trastorno son a menudo añosos y en general presentan otras comorbilidades. Los pacientes a menudo buscan atención médica con síntomas de aturdimiento, pre-síncope, síncope y, en pacientes con periodos alternantes de bradicardia y taquicardia, palpitaciones u otros síntomas asociados con una frecuencia cardíaca rápida. Debido a que los síntomas pueden ser de naturaleza variable, inespecíficos y frecuentemente transitorios, a veces puede ser difícil establecer esta relación síntoma-alteración electrocardiográfica. Los hallazgos electrocardiográficos típicos son uno o más episodios de bradicardia sinusal extrema (Rubenstein Tipo I), o pausas sinusales, paro y bloqueo de salida sinoatrial (Rubenstein Tipo II), o episodios de bradicardia y/o pausas alternantes con taquiarritmias auriculares (Rubenstein Tipo III). Las investigaciones basadas en el registro de electrogramas locales auriculares anormalmente prolongados y fraccionados durante el ritmo sinusal y su distribución característica en la aurícula derecha de pacientes con DNS han aportado un conocimiento importante sobre las propiedades electrofisiológicas de la aurícula patológica. El electrograma auricular anormal traduce una conducción auricular irregular, caracterizada por una actividad eléctrica local no homogénea, relacionada con una conducción anisotrópica, no uniforme y retardada a través de un miocardio auricular patológico, en el que se pueden originar arritmias por reentrada. La detección de electrogramas auriculares anormales en la DNS identifica a un grupo de pacientes con vulnerabilidad auricular aumentada y con una incidencia significativamente mayor de episodios espontáneos o inducidos de fibrilación auricular(AU)

Sinus node dysfunction (SND) is often secondary to senescence of the sinus node and surrounding atrial myocardium. Patients with this disorder are frequently elderly and generally have other comorbidities. Patients with SND often seek medical attention with symptoms of lightheadedness, presyncope, syncope, and, in patients with alternating periods of bradycardia and tachycardia, palpitations and/or other symptoms associated with a rapid heart rate. Because symptoms may be variable in nature, nonspecific, and frequently transient, it may be challenging at times to establish this symptom-rhythm relationship. Typical electrocardiographic findings are one or more episodes of extreme sinus bradycardia (Rubenstein type I), or sinus pauses, arrest, and sinoatrial exit block (Rubenstein type II), or alternating bradycardia and atrial tachyarrhythmias (Rubenstein type III). Investigations based on the recording of abnormally prolonged and fractionated local atrial electrograms during sinus rhythm and their characteristic distribution in the right atrium of patients with SND have provided important knowledge about the pathological atrium electrophysiological properties. Abnormal atrial electrogram results in an irregular atrial conduction, characterized by a non-homogeneous local electrical activity, related to an anisotropic, non-uniform and delayed conduction through a pathological atrial myocardium, in which reentry arrhythmias may arise. Abnormal atrial electrograms detection in SND identifies a group of patients with increased atrial vulnerability and a significantly higher incidence of spontaneous or induced episodes of atrial fibrillation(AU)

Comparative Assessment of the Heart's Functioning by Using the Akabane Test and Classical Methods of Instrumental Examination.

Acupuncture physicians have studied the application of reflexotherapy to cardiology. However, no one has investigated the connection of ancient Chinese diagnostic methods with modern tools. A total of 102 patients (54 men and 48 women) with heart pathology, namely, sick-sinus syndrome, Wolff-Parkinson-White syndrome, and atrioventricular blockade, were studied using the usual instrumental methods (transesophageal electrophysiological study of the heart, echocardiography), after which they underwent Akabane thermopuncture testing as in traditional Chinese medicine. The results of cardio examination from one side of the Akabane test with that from the other side were compared by means of a multiple stepwise regression analysis. We revealed the effects on the characteristic pattern of acupuncture channel lesions inherent in a definite heart pathology, i.e., the most vulnerable acupuncture channel (AC), of such factors as disturbances of the contractile, conductive, or automatic heart functions, and changes in the chambers' size or circulation volume. Сhanges in the indices of the left and the right branches of these channels usually reflect the opposing natures of the changes in these indicators, which should be considered in reflexotherapy. The main value of the Akabane test along with the use of mathematical analysis lies in early, quick, and inexpensive detection of the above-mentioned heart disturbances.

Electrical Remodeling of the Atrioventricular Node Caused by Persistent Atrial Fibrillation in Humans.

BACKGROUND: An animal experiment showed that long-term atrial pacing or persistent atrial fibrillation (AF) caused electrical remodeling of the atrioventricular (AV) node. We aimed to test the hypothesis that persistent AF decreases the AV conductivity in human hearts. METHODS AND RESULTS: We retrospectively compared the cardiac electrophysiological properties between patients with paroxysmal AF who underwent catheter ablation (PXAF, N = 254) and those with persistent or longstanding persistent AF (PSAF, N = 213). The PSAF patients were more likely than PXAF patients to have longer atrial-His (AH) (96.3 ± 25.7 vs. 91.3 ± 20.4 milliseconds; P = 0.02) and His-ventricle (HV) (43.1 ± 9.4 vs. 41.2 ± 8.6 milliseconds; P = 0.02) intervals. The AV nodal effective refractory period (ERP) (299.1 ± 74.6 vs. 276.2 ± 58.9 milliseconds; P < 0.001) and Wenckebach cycle length (420.9 ± 80.3 vs. 386 ± 58.6 milliseconds; P < 0.001) were also more prolonged in the PSAF patients. We found a dual AV nodal physiology with a similar frequency in both groups. The AH interval, fast pathway ERP, and Wenckebach cycle length in the PSAF patients were more likely than in the PXAF patients to be prolonged among the patients without dual pathways, while those intergroup differences were never seen among the patients with dual pathways. In subgroup analyses including only PSAF patients, there was no difference in the AV conductivity between the patients with persistent AF and those with longstanding persistent AF. CONCLUSIONS: Persistent AF may cause a mild decrease in the AV nodal function in human hearts. Electrical remodeling may be uncommon if dual AV nodal pathways are present, and its extent may not depend on the duration of persistent AF.

Device malfunction caused by "auto-oversensing" of transthoracic impedance measurement test pulses in a modern minute ventilation dual-chamber pacemaker.

Oversensing of physiologic and non-physiologic electrical signals is a relevant cause of malfunctions in subjects with CIED. Physicians taking care of CIED patients must be aware of the potential causes of oversensing and their pattern in EGMs. The present case describes an uncommon source and unique underlying root cause for oversensing in a modern dual-chamber MV rate-adaptive pacemaker.

INFLUENCE OF PERMANENT PACING OF THE ATRIA FROM UPPER ANTERIOR AREA OF INTERCARDIAC SEPTA (AREA OF BAKHMAN'S FASCICLES) ON THE PART OF AMOTIVATIONAL VENTRICLE STIMULATION.

This research includes 74 patients with syndrome of the sinus node asthenia. The application of permanent bilocular pacing was indicated for these patients. An atrial electrode was located in the right atrial auricle in 37 patients and it was in the area of Bakhman's fascicles in other 37 patients. All the patients had a stimulated atrio-ventricular delay on 250 ms, but sensing delay was shorter on 20 ms. Given data were analyzed after operation in the periods of 6 and 12 months. Cumulative percent of ventricular stimulation was significantly less in the group with electrode in the area of Bakhman's fascicles (6%) as compared with the group where electrode installed in the right atrial auricle (41%) after 6 months. There were 4% in comparison with 43% after 12 months. The localization of atrial electrode in the area of Bakhman's fascicles led to reduction of cumulative percent of ventricular stimulation on 35% after 6 months and on 39% after 12 months. Permanent pacing in the area of Bakhman's fascicles could be an effective mode to decrease the part of amotivational stimulation of the right ventricle.

Atrial standstill in sinus node disease due to extensive atrial fibrosis: impact on dual chamber pacemaker implantation.

AIMS: Atrial standstill is characterized by the absence of atrial activity. We report about a series of cases, in which conventional atrial pacemaker lead implantation in patients with symptomatic sinus node disease failed due to lack of excitable right atrial tissue, thus, prompting the diagnosis of atrial standstill. We hypothesized that mapping of the atria with subsequent identification of myocardium still amenable to atrial pacing would allow dual chamber pacemaker implantation. METHODS AND RESULTS: In four patients, atrial lead implantation failed. In these patients, spontaneous or fibrillatory electrical activity was absent but the atria could not be captured despite high stimulation voltages at conventional atrial sites. We suspected partial or complete atrial standstill and subsequently confirmed this hypothesis by conventional (n = 1) or electroanatomical mapping (n = 3). Areas of fibrotic tissue were present in all patients as identified by lack of spontaneous electrical activity and inability of local electrical capture via the mapping catheter. Surviving atrial tissue, which could be electrically captured with subsequent conduction of activity to the atrioventricular (AV) node, was present in three patients. Successful targeted atrial lead implantation at these sites was achieved in all these patients. Isolated sinus node activity without conduction to the atria was found in one patient. CONCLUSION: Partial atrial standstill may be present and prevent atrial lead implantation in patients with sinus node disease. In these patients, recognition of partial atrial standstill and identification of surviving muscular islets with connection to the AV node by mapping studies may still allow synchronous AV sequential pacing.

[Atrial mechanical and electrical dysfunction in patient with Emery-Dreifuss muscular dystrophy reason of change in electrotherapeutical approach: frequent result of rare disease]. / Elektryczna i mechaniczna dysfunkcja przedsionków u pacjenta z dystrofia miesniowa Emery-Dreifussa przyczyna zmiany wyboru optymalnej formy elektroterapii: czeste powiklanie rzadkiej choroby.

We present a case of a 35 year-old male patient with Emery-Dreifuss muscular dystrophy diagnosed in the age of 12 who was assigned to dual chamber pacing system due to bradycardia primarily recognised as sinus node insufficiency with the atrio-ventricular nodal rhythm. During the procedure permanent electrical atrial stand-still without atrial capture were detected and the mode of stimulation was change to VVIR.

A tale of early Reel syndrome caused by an over-enthusiastic masseuse.

Twiddler syndrome is a form of pacemaker lead dislocation caused by the coiling of the pacemaker leads due to pulse generator rotation on its long axis. Similar to Twiddler syndrome, Reel syndrome occurs due to rotation of the pulse generator on its transverse axis, leading to lead dislocation or fracture, followed by clinical symptoms of dislodged leads. We report a case of 75 years old woman with Reel syndrome presenting with syncope.

[Antiarrhythmic therapy of paroxysmal tachycardias and extrasystoles in patients with sinus node dysfunction].

Antiarrhythmic therapy of patients with disturbed automatism of the sinus node and impaired atrioventricular conductance may be complicated by hemodynamically significant bradycardias and contraindications for implantation of a cardiac electrical stimulator This study aimed at estimating effect of antiarrhythmic therapy with allapinin on the function of sinus and atrioventricular nodes. It included 20 patients (mean age 37.5+-2.3 years) with disturbed cardiac rhythm and sinus node dysfunction treated with allapinin (37.5 - 50 mg/d per os). This therapy had well apparent antiarrhythmic effect manifest as improvement of supraventricular and ventricular ectopic activities in the absence of negative influence on the function of sinus and atrioventricular nodes.

Comparative study between original and traditional method in establishing a chronic sinus node damage model in rabbit.

Sick Sinus Syndrome is a common and refractory arrhythmia, needing further study in which setting up a credible sinus node damage model is important. To explore the feasibility and superiority of an original formaldehyde pinpoint pressing permeation (FPPP) method for building a chronic sinus node damage (CSND) model, 5 rabbits were chosen from 35 as a sham-operation group, and the remaining were randomly divided into two groups: the formaldehyde wet compressing (FWC) group, in which models were established by applying a cotton bud dipped in 20% formaldehyde onto the sinus node (SN) area, and the FPPP group, in which models were established by injecting formaldehyde into the SN area through a self-made pinpointing and injecting electrode. We found that in both groups, the HR at 2 h, 24 h, 1 wk, and 2 wk after modeling decreased compared with premodeling; sinoatrial conduction time, sinus node recovery time, and corrected sinus node recovery time were prolonged compared with premodeling. The indexes mentioned shortened by 2 wk after modeling compared with 2 h in the FWC group, whereas they were stable after modeling in the FPPP group. The modeling achievement ratio in the FPPP group was higher and the death rate was lower. Under light microscope, paraffin sections of the SN tissue and cells showed severe injury in both groups. The results indicate that the CSND models in rabbits can be successfully established by the FPPP method, with higher achievement ratio, lower death rate, better stabilization effect, and less damaging comparing with the traditional method.

Efficacy of low interatrial septum and right atrial appendage pacing for prevention of permanent atrial fibrillation in patients with sinus node disease: results from the electrophysiology-guided pacing site selection (EPASS) study.

BACKGROUND: The role of pacing sites and atrial electrophysiology on the progression of atrial fibrillation (AF) to the permanent form in patients with sinus node dysfunction (SND) has never been investigated. The aim of the study was to investigate the relationship between atrial electrophysiology and the efficacy of atrial pacing at the low interatrial septum (IAS) or at the right atrial appendage (RAA) to prevent persistent/permanent AF in patients with SND. METHODS AND RESULTS: The Electrophysiology-Guided Pacing Site Selection (EPASS) Study was a prospective, controlled, randomized study. Atrial refractoriness, basal and incremental conduction times from the RAA to the coronary sinus ostium were measured before implantation, and the difference (ΔCTos) was calculated. Patients with ΔCTos ≥ 50 ms (study group) and those with ΔCTos <50 ms (control group) were randomly assigned to RAA or IAS with algorithms for continuous atrial stimulation "on." The primary end point was time to development of permanent or persistent AF within a 2-year follow-up in the study group, IAS versus RAA. Data were analyzed by intention to treat. One hundred two patients (77 ± 7 years, 44 mol/L) were enrolled, 69 (68%) in the study group and 33 (32%) in the control group. Of these, 97 ended the study, respectively, randomly assigned: 29 IAS versus 36 RAA and 18 IAS versus 14 RAA. After a mean follow-up of 15 ± 7 (median, 17) months, 11 (16.6%) patients in the study group met the primary end point: 2 IAS versus 9 RAA (log rank=3.93, P=0.047). CONCLUSIONS: In patients with SND and intra-atrial conduction delay, low IAS pacing was superior to RAA pacing in preventing progression to persistent or permanent AF. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00239226.

Developmental changes in sinus node function in growing children: an updated analysis.

Sinus node dysfunction (SAND) may be congenital or acquired following injury or surgery for congenital heart lesions. Sinus node function is evaluated by electrophysiological (EP) parameters of corrected sinus node recovery time (CSNRT) and sinoatrial conduction time (SACT). The aim of this study was to determine age- and gender-specific values for CSNRT and SACT in pediatric patients without structural congenital heart disease. Data were collected on 152 patients who underwent an EP study for evaluation of supraventricular tachycardia between 1997 and 2002. All patients received midazolam and propofol and/or isoflurane for sedation and anesthesia, which are known to not affect EP parameters. The age of transition at which CSNRT changed significantly was 14 years (241.5 +/- 102.0 msec in patients younger than 14 years old and 285.6 +/- 144.3 msec in those older than 14 years, p < 0.05). The upper limits of normal CSNRT (mean + 2 SD) were significantly higher (445 vs 275 msec) and the upper limits of normal SACT values were lower (120 vs 200 msec) than the currently used norms in the younger age group. CSNRT values and atrial refractory period values were significantly longer in males compared to age-matched females [278.5 +/- 15.3 VS : 236.4 +/- 13.6 msec (p < 0.05) and 269.0 +/- 4.9 VS: 244.7 +/- 6.8 msec (p < 0.005), respectively]. The new age- and gender-specific values of EP parameters, which reflect sinus node function, may enable more precise recognition of SAND.

Flutter auricular crónico: una manifestación infrecuente de enfermedad del nódulo sinusal: caso clínico / Chronic atrial flutter as an infrequent manifestation of sick sinus syndrome: report of 1 case

We report a 41 years old female, previously operated of an atrial septal defect, presenting with a persisting atrial flutter. Sinus node dysfunction became evident during an electrophysiological study at the moment of interrupting the flutter with electrical stimulation. The patient was treated with his bundle ablation and implantation of a definitive pacemaker. After one year of follow up, she is devoid of symptoms