Uncontrolled Diabetes with Underlying Structural Changes in the Atrioventricular Node / Diabetes no Controlada con Cambios Estructurales Subyacentes en el Nodo Atrioventricular

SUMMARY: Diabetic cardiomyopathy, characterized by diabetes mellitus (DM) -induced cardiac muscular abnormalities, is a strong inducer of impaired cardiac contraction and arrhythmia. Atrioventricular block, a serious type of arrhythmia resulting from interruption of cardiac impulse conduction via the atrioventricular node (AVN), frequently occurs among diabetic patients. However, details of structural changes in AVN in DM remain poorly explained. Here, this study defined the effects of DM on the morphological remodeling of the AVN in male Sprague Dawley rats induced by intraperitoneal injection of streptozotocin (60 mg/kg body weight). At 24 weeks, the pathological changes in the AVN were assessed by light microscopy (LM) and transmission electron microscopy (TEM). Under LM, the AVN in diabetic rats became a less compact mass and exhibited the intracellular vacuolation. The nodal cells were more varied in sizes with the absence or shrinkage of nuclei and clear cytoplasm compared to the control. The collagen content significantly increased in relation to the presence of myofibroblasts. Consistent with LM, TEM images of the diabetic nodal cells revealed several signs of cell damage, such as mitochondrial changes, deterioration of cell organelles, gap junction internalization, and cell separation. Furthermore, changes in AVN innervation, evidenced by damaged Schwann cells and axons, were also found. These results indicated alterations in important components in the AVN during diabetic condition, which may lead to the impairment of electrical conduction, causing abnormal cardiac functions in diabetic patients.

La miocardiopatía diabética, caracterizada por anomalías musculares cardíacas inducidas por diabetes mellitus (DM), es un fuerte inductor de alteración de la contracción cardíaca y arritmia. El bloqueo atrioventricular, un tipo grave de arritmia resultante de la interrupción de la conducción del impulso cardíaco a través del nodo atrioventricular (NAV), se produce con frecuencia entre los pacientes diabéticos. Sin embargo, los detalles de los cambios estructurales en NAV en DM siguen estando pobremente explicados. Aquí, este estudio definió los efectos de la DM en la remodelación morfológica del NAV en ratas macho Sprague Dawley inducidas por inyección intraperitoneal de estreptozotocina (60 mg/kg de peso corporal). A las 24 semanas, los cambios patológicos en el NAV se evaluaron mediante microscopía óptica (MO) y microscopía electrónica de transmisión (MET). Bajo MO, el NAV en ratas diabéticas se convirtió en una masa menos compacta y exhibió la vacuolización intracelular. Las células nodales tenían tamaños más variados con ausencia o contracción de núcleos y citoplasma claro en comparación con el control. El contenido de colágeno aumentó significativamente en relación con la presencia de miofibroblastos. De acuerdo con MO, las imágenes MET de las células nodales diabéticas revelaron varios signos de daño celular, como cambios mitocondriales, deterioro de los orgánulos celulares, internalización de uniones comunicantes y separación celular. Además, también se encontraron cambios en la inervación del NAV, evidenciados por schwannocitos y axones dañados. Estos resultados indicaron alteraciones en componentes importantes en el NAV durante la condición diabética, lo que puede conducir al deterioro de la conducción eléctrica, causando funciones cardíacas anormales en estos pacientes.

Prevalence of Atrial Fibrillation in Pacemaker Patients

Abstract Background: Current pacemakers allow for the continuous recording of the occurrence of arrhythmic events. One of the most frequent arrhythmias after implantation of a device is atrial fibrillation (AF), an important risk factor for embolic events. The frequency of this arrhythmia in pacemaker patients has not been widely studied. Objectives: This study aimed to evaluate the prevalence, incidence, and predictors of the occurrence of AF in patients with double-chamber pacemakers and without a history of atrial fibrillation prior to implantation. Methods: A dynamic, retrospective, and prospective cohort study was carried out with 186 patients undergoing biannual follow-up of the double-chamber pacemaker, without previous AF, in a single service, between 2016 and 2018. Clinical data were collected from the medical records and the telemetry of the device and the prevalence, incidence rate, relative risk by univariate analysis (by chi-square), and risk ratio were calculated by multivariate analysis (by Cox regression); values of p<0.05 were considered significant. Results: There was a prevalence of 25.3% FA, with an incidence of 5.64 cases / 100 persons-year. The median time for the development of arrhythmia was 27.5 months. Multivariate analysis identified 5 statistically significant predictors: male gender, OR: 2.54 [1.04-6.15]; coronary artery disease, OR: 2.98 [1.20-7.41]; hypothyroidism, OR: 3.63 [1.46-9.07]; prior heart surgery, OR: 2.67 [1.01-7]; and left atrial enlargement, OR: 2.72 [1.25-5.92]. Conclusions: The prevalence and incidence of AF in this population are high. Risk factors for AF were: male gender, coronary artery disease, hypothyroidism, prior heart surgery, and left atrial enlargement.

Bloqueo auriculoventricular de alto grado idiopático en la infancia: reporte de caso y revisión de literatura / High-grade idiopathic atrioventricular block in childhood: case report and literature review

Los bloqueos auriculoventriculares son aberraciones cronotrópicas producidas por alteraciones de índole multifactorial en el sistema de inervación cardíaco. Específicamente se localizan entre las vías internodales que conducen el potencial de acción desde el nodo sinusal hasta el nodo auriculoventricular. Estos representan el 2,3% de las alteraciones cardíacas en la vida intrauterina, registrándose un caso por cada 20 000 a 25 000 nacidos vivos. Sin embargo, su ocurrencia en la infancia temprana y la edad escolar es desconocida. Asimismo, el porcentaje de causas idiopáticas de bloqueos auriculoventriculares en esta etapa de la vida es desconocido hasta el momento en Colombia. Dentro de las posibles etiologías se han documentado causas congénitas y adquiridas. Algunos ejemplos son casos aislados producto de isoinmunización materna, en hijo de madre lúpica o en coexistencia con alteraciones estructurales como anomalías del septo interventricular de índole neoplásico, defectos relacionados al ostium y la tabicación de las cámaras cardíacas. También se han descrito casos secundarios a infección por virus sincitial respiratorio y miocarditis vírica concomitante, incluyendo cardiomiopatías de origen inmune, reumático, infeccioso, tumoral, estructural, además de aquellas con compromiso mitocondrial en el cardiomiocito (síndrome de Kearns Sayre) con presentación más tardía con afectación multiorgánica. Todas ellas destacan por un fenómeno en común a nivel celular, referente a la inflamación crónica con reparación fibrótica en el sistema de conducción cardíaco, que conlleva alteraciones de la transmisión del potencial de acción y bradicardia con asíncrona auriculoventricular. También se han reportado causas idiopáticas descritas en el debut de una disautonomía primaria. Se presenta el caso de una paciente de 11 años con crisis de cefalea y síntomas vegetativos paroxísticos asociados a lipotimias a repetición, con posteriores estudios de extensión sin identificación de alteraciones estructurales ni hallazgos autoinmunes. A la niña se le diagnosticó bloqueo auriculoventricular completo, idiopático por lo que recibió manejo expectante por parte del servicio de electrofisiología.

Atrioventricular blocks are chronotropic abnormalities produced by multifactorial alterations in the cardiac innervation system, specifically between the internodal pathways between the sinus node and the atrioventricular node. These bradyarrhythmias represent 2.3% of cardiac alterations in intrauterine life, registering one case for every 20 000 to 25 000 live births. However, its occurrence in childhood and adolescence is unknown. Likewise, the percentage of idiopathic atrioventricular blocks in this group in Colombia is unknown to date. Among the possible etiol-ogies, congenital and acquired causes have been documented. Some examples are isolated cases found in pregnancies with maternal isoimmunization, from carriers with lupus, and in coexis-tence with structural alterations, such as anomalies of the interventricular septum due to cardiac tumors and defects in the ostium and septation of the cardiac chambers. Atrioventricular blocks are also associated with respiratory syncytial virus infection and concomitant viral myocarditis and with cardiomyopathies of immune, rheumatic, infectious, tumoral, and structural origin, in addition to mitochondrial diseases such as Kearns Sayre syndrome, presenting with multi- organ involvement. These etiologies lead to chronic inflammation with fibrotic repair in the cardiac conduction system, which alters the transmission of the action potential and bradycardia with atrioventricular asynchrony. Idiopathic causes described in the onset of primary dysautonomia have also been reported. We present the case of an 11- year- old patient with a headache crisis and paroxysmal vegetative symptoms associated with repeated fainting, with subsequent studies where no structural alterations or autoimmune findings were identified. The patient was diag-nosed with idiopathic complete atrioventricular block and received expectant management by the electrophysiology service.

Translational Approach for Percutaneous Interventions for the Treatment of Cardiac Arrhythmias

Abstract New translational concepts on cellular and tissue substrate of cardiac arrhythmias have been responsible for the development of non-pharmacological interventions, with important achievements compared to the conventional approach with antiarrhythmic drugs. In addition, the increasing knowledge of anatomical and electrophysiological studies, sophisticated mapping methods, special catheters, and controlled clinical trials have favored the progression of ablation of tachyarrhythmias, particularly of ventricular tachyarrhythmias and atrial fibrillation.

Effects of selectively resecting the lower half of stellate ganglion on fast ventricular rate in canines with persistent atrial fibrillation / 中国胸心血管外科临床杂志

@#Objective To determine the effects of resecting the lower half of left stellate ganglion (LSG) on fast ventricular rate (VR) in persistent atrial fibrillation (AF) and its mechanism. Methods Twelve mature healthy male beagle dogs (15–25 kg) were studied. They were randomly divided into two groups (an experimental group and a control group, 6 dogs in each group). The control group were merely performed with rapid left atrial pacing to induce persistent AF. The experimental group were disposed with rapid left atrial pacing and received resection of the lower half of LSG after the persistent AF was documented. Simultaneously the ventricular rates were monitored separately before anesthesia, after anesthesia, 30 minutes and one month after LSG resection. The forward passing effective refractory period (ERP) of the canine atrioventricular node (AVN) was also measured. Results Each dog was documented with persistent AF after 3–6 weeks’ left atrial pacing. After resecting the lower half of LSG for 30 minutes (the control group was only observed for 30 minutes without LSG resection), the average VR of the control group attained 144.5±4.2 beats/min, while that of the experimental group was 121.5±8.7 beats/min (P<0.001). After resecting the lower half of LSG for one month (the control group was observed for one month without LSG resection), the average VR of the control group was 139.2±5.6 beats/min, while that of the experimental group was 106.5±4.9 beats/min (P<0.001). Meantime, the forward passing ERP of AVN of the experimental group was significantly prolonged than that of the control group (265.6±7.8 msvs.251.1±4.6 ms, P=0.003). Conclusion Resection of the lower half of LSG is efficient in reducing VR in canines with persistent AF, one of the mechanisms of which may be prolonging the forward passing ERP of AVN.

Radioterapia supradiafragmática y bloqueo auriculoventricular completo / Supradiaphragmatic radiotherapy and complete atrioventricular block

El uso de la radioterapia ha contribuido a mejorar la supervivencia de pacientes con diversos tumores malignos relacionados con la región torácica. No obstante, la irradiación cardíaca a una dosis suficientemente alta puede dañar prácticamente cualquier componente del mismo, incluyendo el sistema de conducción. Se describe el caso de un paciente que desarrolló bloqueo auriculoventricular completo, más de veinte años después de recibir radioterapia supradiafragmática para el tratamiento de un linfoma de Hodgkin.

The use of radiotherapy has contributed to improving the survival in patients with diverse malignancies related to the thoracic region. Nevertheless, cardiac radiation in sufficiently high dose can damage virtually any of its components, including the conduction system. We describe the case of a patient who developed a complete atrioventricular block more than twenty years after receiving supradiaphragmatic radiotherapy for Hodgkin lymphoma.

Effects of different doses of dexmedetomidine on atrioventricular node conduction function in healthy volunteers / 中华麻醉学杂志

Objective To evaluate the effects of different doses of dexmedetomidine on atrioventricular node (AVN) conduction function in the healthy volunteers.Methods Sixteen healthy volunteers of both sexes,aged 18-30 yr,with body mass index of 19-26 kg/m2,were included in the study.Dexmedetomidine was infused in a loading dose of 1.0 μg/kg over 10 min,followed by an infusion of 0.5 μg · kg-1 · h 1 for 50 min (Dose Ⅰ);1-2 weeks later,dexmedetomidine was infused in a loading dose of 1.5 μg/kg over 10 min,followed by an infusion of 0.75 μg · kg-1 · h-1 for 50 min (Dose Ⅱ).Before infusion of dexmedetomidine (T0) and at 15 and 35 min of infusion (T1.2),AVN Wenckebach point,AVN 2 ∶ 1 block point,AVN relative refractory period (AVNRRP),and AVN effective refractory period (AVNERP) were measured.Results AVN Wenckebach point and AVN 2 ∶ 1 block point were significantly decreased,and AVNRRP and AVNERP were significantly prolonged at T1,2 compared with those at T0 (P＜0.05).Compared with Dose Ⅰ,AVN Wenckebach point at T2 and AVN 2 ∶ 1 block point at T1,2 were significantly decreased,and AVNRRP and AVNERP were significantly prolonged at T1,2 in the subjects receiving Dose Ⅱ] (P＜0.05).Conclusion Dexmedetomidine can inhibit AVN conduction function in the healthy volunteers,and the inhibitory effect is enhanced with the increasing doses.

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.

The clinical analysis of 212 cases of transesophageal atrial pacing (TEAP) / 中国基层医药

Objective To discuss the clinical application value of transesophageal atrial pacing ( TEAP) in basic general hospitals.Methods A total of 212 subjects were selected,with dizziness,syncope,paroxysmal palpita-tions and other clinical symptoms and electrocardiogram showed sinus slow, atrioventricular block, short PR interval period,or with the first urgent symptom of tachycardia.The author doubted these symptoms were due to decreased function of the sinoatrial and atrioventricular node or Paroxysmal Supraventricular Tachycardia (PSVT),and treated them with TEAP with xd-5a.Results 121 cases (57.1%) were positive,83 cases(68.6%) of sinoatrial node dys-function,38 cases(31.4%) of PSVT,then sinoatrial node dysfunction were given atropine load experiment and double checked TEAP.The authors detected 57 cases of non-increased vagus nerve tension in 83 positive cases,29 cases (20.1%) of sinoatrial node hypofunction,8 cases of atrioventricular node hypofunction,14 cases of double node hypofunction,6 cases of tachycardia-bradycardia syndrome;38 cases(31.4%) of PSVT,20 cases of dual atrioven-tricular nodal pathways(DAVNP),12 cases of atrioventricular bypass,4 cases of atrial tachycardia(AT),2 cases of ventricular tachycardia( VT);12 cases from 38 cases of positive results manifested as the first urgent symptom of achy-cardia,included 5 cases of DAVNP,5 cases of atrioventricular bypass,overdrive pacing terminated tachycardia suc-cessfully,2 cases of male VT,1 case terminated tachycardia through giving intravenous amiodarone successfully,1 case was taken electrical cardioversion uccessfully.Conclusion The common causes of slow sinus and atrioventricular block and the common cardiac electrophysiological types of PSVT and VT were detected through TEAP examination with the best diagnostic and differential diagnostic value.According to diagnosis guide,clinicians adopted correct and effective treatment strategies with good clinical application value.The author suggest this methods should be used in clinical,especially in basic general hospitals.

Clinical application value of transesophageal atrial pacing combined with atropine load experiment in the diagnosis of the lesions of sinoatrial node and atrioventricular node / 中国综合临床

Objective To evaluate the clinical application value of transesophageal atrial pacing (TEAP) combined with atropine load experiment in the diagnosis of the lesions of sinoatrial node and atrioventricular node.Methods One hundred and forty-four cases selected from the outpatient and hospitalized patients in the People's Hospital of Changji Hui Autonomous Prefecture from September 2009 to December 2012,who with dizziness, syncope and other clinical symptoms and electrocardiogram showe.TEAP combined with atropine load experiment were given to these patients.Results (1) The authors detected in all patients,83 cases (57.6％) were positive, among which, 48 cases (57.8％) male, 35 cases (42.2％) female.(2) The authors detected 57 cases(39.6％) non-increased vagus nerve tension cases in 83 positive cases,among which 33 cases (57.9％) male, 24 cases (42.1％) female;Among which 29 cases (20.1％) were sinoatrial node hypofunction, and 16 cases(55.2％) male;8 cases(5.6％) were atrioventricular node hypofunction,and 4 cases(50％) male;14 cases(9.7％) were double node hypofunction, and 10 cases (71.4％) male;6 cases (4.2％) were tachycardia-bradycardia syndrome, and 3 cases (50％) male;among which, a long interval of greater than 3 seconds appeared when we stimulate one 84 years old man with S1S1 stimulate way, immediately pressed protective pacemaker until his own sinus rhythm was restored, as a safety precaution, stoped further examination and classified him as sick sinus group.Conclusion Detect the common causes of slow sinus and atrioventricular block,such as the sinoatrial node dysfunction, atrioventricular node dysfunction, double node dysfunction and increased vagus nerve tension through TEAP combined with atropine load experiment.Consider that this methods have the best diagnostic value in decreasing its rate of false positivity,and should be used as a necessary check before implantation of pacemaker in such patients, suitable used in clinical, especially in basic general hospitals.

Right coronary artery anatomy: anatomical and morphometric analysis / Anatomia da artéria coronária direita: análises anatômicas e morfométricas

BACKGROUND: It is necessary knowing the large variability of right coronary (RCA) artery specialty for its implications in surgical procedures and clinic events. This variability is usually related to the length, branches quantity, origin and irrigated territories. OBJECTIVE: To evaluate by direct examination the morphologic expression of RCA in Colombian people. METHODS: RCA were measured in 221 fresh hearts by RCA ostium canalization with polyester synthetic resin that was injected in their branches. RESULTS: The caliber of the RCA proximal segment and at the level of the acute angle of the heart was 3.42 ± 0.66 mm and 2.9 ± 0.50 mm, respectively. It ended between crux cordis and the left margin in 75.6 percent of specimens. Posterior interventricular artery (PIA) reached the inferior third, or the apex, or the anterior interventricular sulcus in 149 (67.4 percent) cases. Sinoatrial node artery (SNA) originated in the right coronary in 134 (60.6 percent) cases, 77 (34.9 percent) from circumflex artery (CxA) and from both in 10 (4.5 percent). Posterior right diagonal artery (PRDA) was noted in 38 (17.2 percent) hearts, but only 6 percent of the sample with long PIA, concomitantly presented the PRDA (P = 0.001). In right dominance SNA were originated from RCA in 54.7 percent and form CxA in 46.3 percent (P = 0.06). CONCLUSIONS: Caliber of the RCA and its branches is lesser than the majority of previous studies, while the PRDA frequency is slightly higher than the reported in literature. Clinical and pathological scenarios by these variations should be taken into account: hemodynamic procedures, cardiac surgery and arrhythmias from coronary occlusive disease.

INTRODUÇÃO: É necessário conhecer a grande variabilidade da artéria coronária direita (ACD), especialmente por suas implicações nos procedimentos cirúrgicos e eventos clínicos. Esta variabilidade está geralmente relacionada à extensão, à quantidade de ramos, à origem e aos territórios irrigados. OBJETIVO: Avaliar por exame direto a expressão morfológica da ACD em sujeitos colombianos. Métodos: As ACD foram medidas em 221 corações frescos pela canalização do óstio da ACD com uma resina de poliéster sintético que foi injetada em seus ramos. RESULTADOS: O calibre do segmento proximal da ACD e ao nível do ângulo agudo do coração foi de 3,42 ± 0,66 mm e 2,9 ± 0,50 mm, respectivamente. A ACD terminou entre a crux cordis e a margem esquerda em 75,6 por cento da amostra. A artéria interventricular posterior (AIP) atingiu o terço inferior, o ápice ou o sulco interventricular anterior em 149 (67,4 por cento) casos. A artéria do nó sinoatrial (ANS) surgiu da artéria coronária direita em 134 (60,6 por cento) casos, 77 (34,9 por cento) da artéria circunflexa (ACx) e de ambas em 10 (4,5 por cento) amostras. A artéria diagonal posterior direita (ADPD) foi observada em 38 (17,2 por cento) corações, mas apenas 6 por cento da amostra com uma AIP longa, apresentaram a ADPD (P=0,001). Em corações com dominância direita, a ANS surgiu da ACD em 54,7 por cento e da ACx em 46,3 por cento dos casos (P=0,06). CONCLUSÕES: O calibre da ACD e seus ramos é menor do que o relatado na maioria de estudos anteriores, enquanto que a frequência da ADPD é ligeiramente superior ao relatado na literatura. Cenários clínicos e patológicos por estas variações devem ser levados em conta: procedimentos de hemodinâmica, cirurgia cardíaca e arritmias de doença coronária obstrutiva.

Características morfológicas y posibles implicaciones clínicas de las arterias nodales / Morphological characteristics and potential clinical implications of nodal arteries

La expresión morfológica de las arterias nodales es relevante en el diagnóstico y manejo de eventos clínicos y en abordajes quirúrgicos del corazón. Se estudiaron 88 arterias nodales de corazones obtenidos como material de autopsia. Las arterias coronarias se inyectaron con resina poliéster pigmentada de color rojo. Se registraron las formas de presentación de las arterias nodales y sus características morfométricas. La arteria del nodo sinoatrial se originó de la coronaria derecha en 52 casos (59,1 porcentaje), de la circunfleja en 33 corazones (37,35 porcentaje) y de ambas en 3 (3,4 porcentaje). Su calibre proximal fue de 1,31 mm (más o menos 0,3), correspondiente a las arterias originadas de la coronaria derecha de 1,25 mm (más o menos 0,3) mientras que las que se originaron de la arteria circunfleja obtuvieron un calibre de 1,42 mm (más o menos 0,3), siendo esta diferencia significativa (p= 0,01). Se originó con mayor frecuencia en el tercio anteromedial, tanto de la coronaria derecha como de la circunfleja (54,6 porcentaje y 61,2 porcentaje respectivamente). En su segmento final cruzó por delante de la desembocadura de la vena cava superior en la mayoría de los casos (44 porcentaje), mientras que en 22 corazones (24,5 porcentaje) cursó alrededor de la cava. Se observó arteria en forma de ®S¼ en 14 casos (15,9 porcentaje del total de la muestra y 42,4 porcentaje de las originadas de la arteria circunfleja). La arteria del nodo atrioventricular se originó del segmento en ®U¼ invertida de la coronaria derecha, al nivel de la cruz cardiaca, en 81 corazones (92 porcentaje), y presentó un calibre proximal de 1,06 mm (más o menos 0,22). Con relación al calibre y al origen se evidencian hallazgos que coinciden con estudios previos. Se destaca la alta prevalencia de la arteria en forma de ®S¼ y de la trayectoria de la arteria sinoatrial alrededor de la vena cava superior.

The morphological expression of nodal arteries is important in the diagnosis and management of cardiac clinical events and surgical approaches. 88 nodal arteries of hearts obtained from autopsies were studied. Coronary arteries were injected with polyester resin pigmented with red. Morphological and morphometrical characteristics of nodal arteries were registered. The sinoatrial node artery had its origin in the right coronary artery in 52 cases (59,1 percentage), in the circumflex in 33 (37,35 percentage), and in both in 3 (3,4 percentage). Its proximal caliber was 1,31mm (more or less 0,3), corresponding to the arteries originated in the right coronary artery of 1,25 mm (more or less 0,3), while those that originated in the circumflex artery had a caliber of 1,42 mm (more or less 0,3), difference that was significant (p= 0,01). Its origin occurred more frequently in the anteriomedial third of both the right coronary artery and the circumflex artery (54,6 percentage and 61,2 percentage respectively). In its final segment, it crossed in most cases (44 percentage) in front of the cava vein, while in 22 hearts (24,5 percentage) went around the cava vein. In 14 cases the artery had an ®S¼ shape (15,9 percentage of the total sample and 42,4 percentage of those arising from the circumflex artery). The atrioventricular node artery was originated from the segment in inverted ®U¼ of the right coronary artery, at the level of the crux cardia in 81 hearts (92 percentage) and had a proximal caliber of 1,06 mm (more or less 022). In relation to the caliber and origin, the findings are consistent with previous studies. Prevalence of ®S¼ shape artery and trajectory of the sinoatrial artery around the superior cava vein are highlighted.

An improved in vivo method for atrioventricular node ablation via thoracotomy

The atrioventricular (AV) node is permanently damaged in approximately 3 percent of congenital heart surgery operations, requiring implantation of a permanent pacemaker. Improvements in pacemaker design and in alternative treatment modalities require an effective in vivo model of complete heart block (CHB) before testing can be performed in humans. Such a model should enable accurate, reliable, and detectable induction of the surgical pathology. Through our laboratory’s efforts in developing a tissue engineering therapy for CHB, we describe here an improved in vivo model for inducing chronic AV block. The method employs a right thoracotomy in the adult rabbit, from which the right atrial appendage may be retracted to expose an access channel for the AV node. A novel injection device was designed, which both physically restricts needle depth and provides electrical information via electrocardiogram interface. This combination of features provides real-time guidance to the researcher for confirming contact with the AV node, and documents its ablation upon formalin injection. While all animals tested could be induced to acute AV block, those with ECG guidance were more likely to maintain chronic heart block >12 h. Our model enables the researcher to reproduce both CHB and the associated peripheral fibrosis that would be present in an open congenital heart surgery, and which would inevitably impact the design and utility of a tissue engineered AV node replacement.

Origem das artérias dos nós sinoatrial e atrioventricular em população do sul da Índia: um estudo angiográfico / Origin of the sinoatrial and atrioventricular nodal arteries in South Indians: an angiographic study / Origen de las arterias de los nódulos sinusal y atrioventricular en población del Sur de la India: un estudio angiográfico

Fundamento: Estudar o suprimento arterial do sistema condutor e sua correlação com a dominância das artérias coronárias em população do sul da Índia. Objetivo: Determinar angiograficamente as origens da artéria do nó sinoatrial (AnSA) e artéria do nó atrioventricular (AnAV) em indianos.Métodos: O estudo incluiu 300 pacientes consecutivos (114 do sexo feminino e 186 do sexo masculino; idade média, 55 anos), habitantes da região costeira ao sul da Índia, submetidos a cineangiocoronariografia devido a sintomas como dor no peito, angina pectoris ou teste ergométrico positivo. As angiografias incluíram ambas as artérias coronárias (direita e esquerda) em posição oblíqua anterior direita e esquerda. A origem da AnSA e AnAV a partir das artérias coronárias foi observada e correlacionada à dominância arterial. Resultados: O nó SA (sinoatrial) recebeu suprimento pela artéria coronária direita (ACD) em 53% dos casos, pelo ramo circunflexo (Cx) da artéria coronária esquerda (ACE) em 42,66% dos casos, e em 4,33% dos casos esse nó foi irrigado por ambas as artérias coronárias. O nó AV (atrioventricular) também recebeu suprimento sanguíneo com mais frequência da ACD (72,33% dos casos) do que do ramo Cx da ACE (27,66%). Surpreendentemente, em nenhum caso este nó recebeu suprimento de ambas as artérias coronárias. Conclusão: Os resultados do presente estudo podem auxiliar os cirurgiões cardíacos, sobretudo em cirurgias relacionadas a valvopatias, devido à franca proximidade entre os ramos nodais e o complexo valvar.

Background: To study the arterial supply of the conducting system and its correlation with the dominance of the coronary arteries in the South Indian population. Objective: To determine angiographically the origins of the sinoatrial nodal artery (SAna) and atrioventricular nodal artery (AVna) in Indians. Methods: The study included 300 consecutive patients (114 females, 186 males; mean age, 55 years) living in the southern coastal region of India, who underwent coronary angiography either for the symptoms of chest pain, angina pectoris or positive Treadmill Test. The angiograms contained both coronary arteries (right and left) in the right and left anterior oblique position. The origin of SAna and AVna from the coronary arteries was observed and correlated with the arterial dominance.Results: The SA (sinoatrial) node was supplied by the right coronary artery (RCA) in 53% of the cases, by the circumflex (Cx) branch of left coronary artery (LCA) in 42.66%, and by both coronary arteries in 4.33% of cases. The AV (atrioventricular) node was also more often supplied by the RCA (72.33% of cases) than by the Cx branch of the LCA (27.66%), and surprisingly in none of the cases was this node supplied by both coronary arteries. Conclusion: The results of the present study may help cardiac surgeons, particularly in surgeries related to certain valvular disorders, due to the proximity of the nodal branches to the valve complex.

Fundamento: Estudiar el suministro arterial del sistema conductor y su correlación con la dominancia de las arterias coronarias en población del Sur de la India. Objetivo: Determinar angiográficamente los orígenes de la arteria del nódulo sinusal (AnSA) y la arteria del nódulo atrioventricular (AnAV) en indios. Métodos: El estudio incluyó 300 pacientes consecutivos (114 del sexo femenino y 186 del sexo masculino; edad promedio, 55 años), habitantes de la región costera al Sur de la India, sometidos a cineangiocoronariografía debido a síntomas como dolor en el pecho, angina pectoris o test ergométrico positivo. Las angiografías incluyeron ambas arterias coronarias (derecha e izquierda) en posición oblicua anterior derecha e izquierda. El origen de la AnSA y AnAV a partir de las arterias coronarias se observó y se correlacionó con la dominancia arterial. Resultados: El nódulo SA (sinusal) recibió suministro por la arteria coronaria derecha (ACD) en el 53% de los casos, por la rama circunfleja (Cx) de la arteria coronaria izquierda (ACI) en el 42,66% de los casos, y en el 4,33% de los casos este nódulo fue irrigado por ambas arterias coronarias. El nódulo AV (atrioventricular) también recibió suministro sanguíneo con más frecuencia de la ACD (72,33% de los casos) que la rama Cx de la ACI (27,66%). Sorprendentemente, en ningún caso este nódulo recibió suministro de ambas arterias coronarias.Conclusión: Los resultados del presente estudio pueden auxiliar a los cirujanos cardíacos, sobre todo en cirugías relacionadas a valvulopatías, debido a la franca proximidad entre las ramas nodales y el complejo valvular.

Clinical and Electrophysiologic Characteristics and Efficacy of Radiofrequency Catheter Ablation of the Elderly Patients with Atrioventricular Nodal Reentrant Tachycardia

BACKGROUND AND OBJECTIVES: Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common regular supraventricular tachycardias in both the general population and elderly patients. The aim of this study is to investigate the clinical and electrophysiologic characteristics and efficacy of radiofrequency catheter ablation (RFCA) for treating AVNRT in the elderly. SUBJECTS AND METHODS: This study included 273 consecutive symptomatic AVNRT patients who underwent RFCA for the slow-pathway. The study population was divided into two groups: group I patients were younger than 65 years (n=227, average age: 44.6+/-12.9 years, male : female=89 : 138) and group II patients were older than 65 years (n=46, average age: 69.0+/-3.6, male : female=9 : 37). We compared the baseline clinical, electrocardiographic and electrophysiologic characteristics and the outcomes of RFCA between the two groups. RESULTS: The prevalence of a baseline prolonged PR interval (>200 ms) was not different between the 2 groups (1.8% vs. 6.5%, p>0.05). The baseline sinus cycle length, QT interval and AVNRT cycle length were significantly longer in group II than in group 1 (799.3+/-146.1 ms vs. 864.3+/-159.8 ms, 374.2+/-42.1 ms vs. 397.6+/-40.4 ms, 351.3+/-43.2 ms vs. 384.9+/-57.0 ms, respectively p or =second degree) was not different between the two groups (4.0% vs. 6.5%, p>0.05). One patient in group I required permanent pacemaker implantation. CONCLUSION: RFCA in elderly patients is safe and effective as in younger patients. Therefore, performing RFCA for treating AVNRT should also be considered in the elderly patients.

Modified electrocardiographic algorithm for differentiating typical atrioventricular node reentrant tachycardia from atrioventricular reciprocating tachycardia mediated by concealed accessory pathway / 中国实用内科杂志

Objective To evaluate the frequently used electrocardiographic criteria and propose a modified algorithm for differentiating typical atrioventricular node reentrant tachycardia(AVNRT)from atrioventricular reciprocating tachycardia(AVRT).Methods Twelve-lead electrocardiograms(ECGs)during sinus rhythm and atrioventricular node reentrant tachycardia(AVNRT)or atrioventricular reciprocating tachycardia(AVRT)with a narrow QRS complex were obtained from 154 patients who had received successful radiofrequency catheter ablation from Jan.2003 to Nov.2005.The ECGs of initial 104 patients were analyzed by 3 observers without knowledge of the electrophysiological diagnosis.According to these initial results,we proposed a modified stepwise ECG algorithm which used pseudo r′/S/Q waves,RP interval,and ST-segment elevation in lead aVR during tachycardia.Two observers assessed the algorithm in additional 50 patients.Results The algorithm was able to increase the overall accuracy from 77% and 79% with original algorithm to 84% and 87% with the modified algorithm,respectively.The inter-observer concordance was 85%.The intra-observer concordance was 89% in both investigators.Conclusion The modified algorithm can improve the accuracy of differential diagnosis between typical AVNRT and AVRT via concealed accessory pathway.

Primary culture of atrioventricular nodal cells in newborn rabbit / 西安交通大学学报(医学版)

polyhornal and round cells.Conclusion The AVN of rabbit was made up by different cells.The polyhornal and round cells may be pacemaker cells;the spindle cells might be transitional cells,and the triangle cells may be myocardial cells.

His bundle pacing and atrio-ventricular nodal ablation guided by intracardiac echocardiography / 中华超声影像学杂志

Objective To develop an in vivo procedure f or His bundle pacing (HBP) and radio-frequency (RF) ablation of the atrio-ventricular node (AVN) guided by intracardiac echocardiography (ICE) and tissue Doppler imaging (TDI). The procedure included a custom designed bipolar active fixation pacing lead and steerable delivery catheter, and a commercial RF generator and ablation catheter. Methods Six anesthetized- closed-chest canines were tested. The anatomy in the His bundle and AVN regions, and the onset of myocardial electro-mechanical activation were identified using ICE and TDI. The lead and RF ablation catheter were navigated using an ICE catheter (for local detailed imaging) and fluoroscopy (for global imaging). Surface QRS morphologies were recorded to confirm HBP and third degree block post-ablation. Results Direct His bundle pacing was achieved in one canine, and His + ventricular septal pacing in the remaining five. QRS width in sinus rhythm and HBP were ( 59.7-? 5.3-)ms and ( 82.8-? 16.6-)ms separately (P= 0.02-). The increased QRS width for HBP was due to early septal activation. HBP thresholds were ( 3.0-? 1.0-) volts at 0.5 ms (N=5 due to a late exit block). The mean procedure durations were: HBP 40 minutes (3 to 81 minutes), AVN ablation 3 minutes (2 to 5 minutes), and total X-ray exposure 13 minutes (1 to 55 minutes). Post-mortem analysis of the lead and ablation lesions confirmed correct anatomic localization for HBP and AVN ablation. Conclusions ICE provides precise anatomic guidance of HBP lead implantation and AVN ablation and can significantly reduce exposure to fluoroscopy.

Preliminary study on the mechanism of 2:1 atrioventricular block during atrioventricular node reentrant tachycardia / 中国介入心脏病学杂志

Objective The purpose of this study was to clarify the mechanism of 2:1 atrioventricular block (AVB) during AV node reentrant tachycardia (AVNRT) induced during electrophysioloic study.Methods In consecutive patients with AVNRT referred for electrophysiologic study, the data of 2 : 1 AVB during induced AVNRT was retrospectively analysed. Results The data of 4 patients was excluded from analyzing because of the unsatisfactory recording of His bundle potential during AVNRT. A His bundle deflection was present in the blocked beats in three of the remaining 5 patients and absent in the other two. At the beginning of AVNRT induced in those patients whose His bundle deflection was present in the blocked beats, H-V Wenckebach sequence with a QRS pattern of RBBB or LBBB was seen preceding and following the 2 : 1 AVB. A pattern of H-V Wenckebach phenomenon occurred once during AVNRT with 2:1 AVB in one of the two patients whose His bundle deflection was absent in the blocked beats.Conclusion The induced 2:1 AVB during AVNRT is due to functional block in the His-Purkinje system regardless of the presence or absence of a His bundle deflection in blocked beats.