Changes of cardiac electrophysiological parameters after destruction of epicardial nervous plexi innervating sinoatrial node

Electrophysiological methods were used in experiments on 15 dogs for the study of topography of right atrial epicardial nerves, their connections with sinoatrial node, and possibilities of selective surgical denervation of sinoatrial node. Epicardial nerves were electro-coagulated or cryo-destructed in ventral, lateral and dorsal atrial zones near base of vena cava inferior. The following parameters were registered: heart rate, time of restoration of sinus node function, conduction through atrioventricular node, refractoriness of atria and atrioventricular node. Comparison of cardiac parameters before and after destruction of epicardial nerves showed that in lateral and ventral zones sympathetic nerves reach sinus node through lateral and ventral zones while parasympathetic -- along dorsal zone. Selective surgical destruction allows to modify sinus node function in a desired way.     

Extended atrial conduction system characterised by the expression of the HCN4 channel and connexin45

OBJECTIVE: In the heart, there are multiple supraventricular pacemakers involved in normal pacemaking as well as arrhythmias and the objective was to determine the distribution of HCN4 (major isoform underlying the pacemaker current, I(f)) in the atria. METHODS: In the atria of the rat, the localisation of HCN4 and connexins was determined using immunohistochemistry, and electrical activity was recorded using extracellular electrodes. RESULTS: As expected, HCN4 and Cx45 (but not Cx43) were expressed in the sinoatrial node extending from the superior vena cava down the crista terminalis. The same pattern of expression of HCN4 and connexins was observed in a novel tract of nodal-like cells extending from the superior vena cava down the interatrial groove. Although the sinoatrial node was usually the leading pacemaker site, the novel tract of HCN4-expressing cells was capable of pacemaking and could act as the leading pacemaker site; there was evidence of a hierarchy of pacemakers. The same pattern of expression of HCN4 and connexins was also observed in the atrioventricular ring bundle (including the atrioventricular node) encircling the tricuspid valve, but not in the atrioventricular ring bundle encircling the mitral valve. HCN4 was not expressed in the pulmonary veins. CONCLUSIONS: The widespread distribution of HCN4 can explain the widespread location of the leading pacemaker site during sinus rhythm, the extensive region of tissue that has to be ablated to stop sinus rhythm, and the widespread distribution of ectopic foci responsible for atrial tachycardia.     

The Warden Procedure through a Posterolateral Thoracotomy Approach

The Warden procedure for the correction of a right-sided partial anomalous pulmonary venous connection to the high superior vena cava is well established. It has the advantages of avoiding sinoatrial node dysfunction and pulmonary and systemic venous obstruction. In the case related here, a 3-year-old girl presented with a superior vena cava type of sinus venosus atrial septal defect and an anomalously draining right upper pulmonary vein, with bilateral superior venae cavae. Our approach to the Warden procedure was through a right posterolateral thoracotomy, which provided additional advantages.     

Anatomical variants of sinoatrial and atrioventricular node arteries

The authors investigated on 70 hearts taken from deceased subjects of either sex, aged 19 to 75 years, anatomical variants of sinoatrial (SAN) and atrioventricular node (AVN) arteries. As regards the branching of the SAN artery from the right and left coronary artery (RCA, LCA), they found altogether 14 variants of connection with the anterior atrial sulcus and the orifice of the superior vena cava. As regards the branching of the AVN from the RCA and the LCA, they identified altogether 6 variants of connection with the venous sinus orifice and the base of the interventricular septum. Problems of surgical interventions on SAN and AVN arteries and mechanisms of possible traumatization in the course of these operations are discussed. Surgical lesions can be prevented by thorough analysis of coronarograms and by taking into account anatomical variants of SAN and AVN arteries.     

Sinus Node Dysfunction Associated with Isolated Left Superior Vena Cava

The absence of the right superior vena cava with persistance of the left is a rare venous anomaly, which occurs in 0.05% of general population. This anomaly has been associated with other congenital cardiac defects but rarely with sinus node dysfunction. We report the case of a 52-year-old woman who suffered from symptomatic bradycardia that was associated with supraventricular arrhythmias, and refractory to drugs. Implantation of a pacemaker was necessary and an AAI mode possible because of normal atrioventricular conduction. Insertion of the PM lead was performed via the right cephalic vein, then conducted through the innominate vein into the left persistent superior vena cava, leading to the right atrium via the coronary sinus. The electrode was fixed to the right atrial lateral wall; stimulation threshold was within normal limits. Digital angiography of superior venous inflow confirmed complete absence of the right superior vena cava and described a dilated coronary sinus. No other structural heart disease was present. In accordance with reports in the literature, we found the absence of right superior vena cava complicated by sick sinus syndrome and suggest an etiologic link between these two afflictions. Sinus node function should be studied whenever this venous anomaly is discovered in presence of evocated symptoms.     

Accuracy of Fluoroscopic Localization of the Crista Terminalis Documented by Intracardiac Echocardiography

The crista terminalis is an important anatomic target for ablation of atrial arrhythmias. We determined the accuracy of catheter placement guided by fluoroscopy alone when directed to 24 sites along the crista terminalis in 6 patients. The sites selected included the most medial superior, most lateral superior, mid lateral, and most inferolateral sites along the crista terminalis in each patient. These sites were selected because of their recognized importance in sinus node and/or atrial tachycardia ablation and the importance of avoiding caval structures when targeting the most superior and/or inferior right atrium. The position of the catheter tip was documented using a catheter based ultrasound transducer in the right atrium or vena cava. The operator was blinded to the intracardiac echocardiographic (ICE) results until reviewing the images after the procedure in each patient.The catheter tip, guided by fluoroscopy alone, was identified by ICE to be within the right atrium and within 1cm of the crista terminalis at only 10 of the 24 sites (42%). Importantly, when targeting the most superior and inferior sites along the crista terminalis, the catheter tip, guided by fluoroscopy, was noted to be adjacent to the venous junction with the right atrium but actually located in the superior or inferior vena cava at 5 of the 18 such sites. The catheter was positioned appropriately (within 1cm of the crista and within the right atrium) guided by fluoroscopy alone when targeting 1 of the 12 sites in the first 3 patients versus 9 of 12 sites in the last 3 patients, p<0.05. In conclusion, it appears that using fluoroscopic guidance alone: 1) localization of the crista terminalis is frequently inaccurate and 2) catheter positioning in the superior/inferior vena cava is commonly noted when targeting very superior and inferior sites along the crista terminalis. A learning curve, assisted by review of ICE recordings after each procedure, appears to improve the accuracy of catheter placement by fluoroscopy alone but still does not result in uniform success. ICE appears to facilitate and ensure accurate targeting of specific anatomic sites along the crista terminalis and thus may serve as an important adjunctive imaging technique in electrophysiology.     

Anatomical diversity and age-related histological changes in the human right atrial posterolateral wall.

AIMS: Recent clinical observations suggest that the right atrial posterolateral wall structures originate ectopic beats and function as anatomical obstacles. Because atrial arrhythmias increase in incidence after middle age, we investigated histological diversity and age-related changes in right atrial posterolateral wall. METHODS AND RESULTS: Twenty-six autopsied hearts (mean 65.2 years, 16 men and 10 women) were studied. The entire posterolateral right atrium was cut serially. We determined the distribution of the sinoatrial node and localized it in relation to the crista terminalis and sinus venosus. We also compared histopathological changes in these tissues between three groups consisting of 31- to 50-year-old, 51- to 70-year-old and 71- to 90-year-old hearts. Total mean length of the crista terminalis, the sinoatrial node, and the sinus venosus was 46 mm, 21 mm and 29 mm, respectively, and showed no age-related changes, but the distribution of the sinoatrial node was varied. Mean muscular volume of the sinus venosus was significantly reduced in the two older groups, though that of the crista terminalis showed no age related-changes. CONCLUSION: Histological diversity of the sinoatrial node and age-related changes in the sinus venosus beneath the sinoatrial node may enhance histological heterogeneity and hence arrhythmogenicity.     

Sinoatrial and intra-atrial conductive disorders. The value of recording the sinus node potential

Direct recording of the sinus node potential in the bipolar mode using two electrodes of a quadripolar recording catheter positioned in the region of the sinus node at the junction of the superior vena cava to the right atrium was performed in 24 patients. Asynchronous overdrive atrial pacing was carried out using Strauss 'technique. Pharmacological denervation was carried out using intravenous propranolol (0,02 mg/kg) and atropine (0,04 mg/kg) using Jose's technique. An intravenous injection of a bolus of 20 mg of ATP was given in 3 cases. The sinus potential was identified by morphological criteria and confirmed after carotid sinus compression and atrial extrastimuli to exclude artefacts, especially the end of ventricular repolarisation of the preceding complex. The sinoatrial conduction time measured directly under basal conditions was considered normal when within 80 to 150 ms. Direct measurement of the sinus potential in the diagnosis of sinus node dysfunction seems to be less useful than the indirect techniques. On the other hand, it does confirm the diagnosis of sinoatrial block: five cases of special interest are described; in four cases the degree of sinoatrial block was variable: a significant increase of sinoatrial conduction time under basal conditions in 1 case; paroxysmal 3rd degree sinoatrial block revealed by programmed atrial stimulation in 2 cases; 2nd degree 2/1 sinoatrial block after injection of ATP in which the direct sinoatrial conduction time and sinus node function had been considered to be normal (1 case).(ABSTRACT TRUNCATED AT 250 WORDS)     

Double superior vena cava with drainage of the right superior vena cava into the left auricle. Presentation as a cerebral abscess in an adult

A 44 year old man presented with a cerebral abscess, the location of which suggested a septicaemic origin. Although the patient was not cyanosed, a cardiological work-up was requested to exclude a right-to-left shunt. This showed a double abnormality of the systemic venous drainage: presence of an abnormal left superior vena cava draining into the coronary sinus and of a right superior vena cava draining into the left atrium. These two vena cava intercommunicated by anastomoses. Angiography in the right superior vena cava after occlusion by balloon catheter at its junction with the left atrium showed flow from the right to the left superior vena cava and to the azygos system. Simple ligature of the right superior vena cava was therefore performed to prevent recurrence of cerebral abscess. This case is rare and of interest because of the presence of two superior vena cavae, one on the right draining into the left atrium and the other on the left draining into the coronary sinus, with anastomoses between the two superior vena cavae. This double abnormality of systemic venous drainage explains the absence of cyanosis and therefore the relatively late detection of this malformation.     

Sinus node dysfunction associated with absence of right superior vena cava.

A 41-year-old man presented with dizziness associated with sinus bradycardia and sinus arrest. An attempt to implant a transvenous pacing lead was frustrated by absence of the right superior vena cava. The left superior vena cava persisted and drained via the coronary sinus into the right atrium. Absence of the right superior vena cava may present with symptomatic sinus node dysfunction and may require an epicardial demand pacing system.     

Echocardiography of the coronary sinus in adults

The coronary sinus (CS) is a small tubular structure just above the posterior left atrioventricular junction. The CS can be imaged in several different echocardiographic views. Using zoom M-mode recordings of the CS in apical two-chamber view, CS caliber can be sharply imaged and easily measured during different phases of the cardiac cycle. We have recently shown that the CS narrows during atrial contraction in persons with sinus rhythm, but does not narrow at all if atrial fibrillation is present. Attenuation of CS narrowing occurs in patients with congestive heart failure and inferior vena cava plethora. Maximal CS caliber occurs during ventricular systole. Patients with poor left ventricular systolic function show mild CS dilatation. Greater CS dilatation is present in patients with persistent left superior vena cava, and huge dilatation when this anomaly is accompanied by absence of a right superior vena cava. Injection of sonicated saline into a left and then a right arm vein is diagnostically useful in confirming these two venous anomalies. Pulsed-wave Doppler of the CS can be recorded in the parasternal right heart inflow view. From this and from the CS cross-section area it may be possible to estimate coronary blood flow.     

Sinus node dysfunction associated with absence of right superior vena cava.

A 41-year-old man presented with dizziness associated with sinus bradycardia and sinus arrest. An attempt to implant a transvenous pacing lead was frustrated by absence of the right superior vena cava. The left superior vena cava persisted and drained via the coronary sinus into the right atrium. Absence of the right superior vena cava may present with symptomatic sinus node dysfunction and may require an epicardial demand pacing system.     

Hemodynamic and electrophysiologic results of the Senning procedure for transposition of the great arteries

Of 24 patients, aged 6 days to 24 months, undergoing the Senning procedure for transposition of the great arteries, 2 patients died perioperatively (8% operative mortality): 1 patient, a neonate, from sepsis and 1 patient, born prematurely and with multiple anomalies, from congestive heart failure. One patient died late postoperatively from noncardiac causes. The 21 survivors are clinically well, and in 20 complete hemodynamic and electrophysiologic data were obtained by cardiac catheterization a mean of 13 months after repair. All patients have normal systemic arterial oxygen saturation. Left ventricular function and pulmonary artery pressures are normal in all. None had pulmonary venous obstruction. Narrowing at the junction of the superior vena cava and systemic venous atrium with mean pressure differences of 5 mm Hg or more was found in 4 of the 20 patients, but was clinically manifest in only 1 patient. No abnormality of atrioventricular conduction was seen in response to programmed electrical stimulation. Sinus node dysfunction was present in 6 patients, with abnormalities of both automaticity and sinoatrial conduction. Among these 6 patients were the 5 who were younger than 5 months at operation. The Senning procedure generally results in excellent hemodynamic and electrophysiologic status in patients who undergo operation after the newborn period. Identification of sinus node dysfunction, seen in patients in whom the procedure is performed in the first few months of life, is of concern and identifies a need for close follow-up of sinus node function in this cohort of patients.     

Selective stimulation of parasympathetic nerve fibers to the human sinoatrial node.

BACKGROUND. In animals, parasympathetic nerve fibers that innervate the sinoatrial node can be selectively stimulated to increase atrial cycle length. These nerve fibers course through an epicardial fat pad at the margin of the right superior pulmonary vein, the superior vena cava, and the right atrium. We hypothesized that similar nerves exist and can be selectively stimulated in humans. METHODS AND RESULTS. Microscopic examination of fat pads excised from the margin of the right superior pulmonary vein, the superior vena cava, and the right atrium during two human autopsies revealed the presence of nerve fibers and ganglia. We electrically stimulated this epicardial fat pad in 16 patients during cardiac surgery. The fat pads were stimulated with continuous-pulse trains for 15 seconds via a hand-held bipolar electrode using constant current (10-15 mA), constant pulse width (0.02-0.05 msec), and at 6.6, 10, 20, 25, and 30 Hz. The mean atrial cycle length +/- 1 SEM increased from 734 +/- 34 msec at baseline to a maximum of 823 +/- 61 msec at 6.6 Hz, 1,167 +/- 125 msec at 10 Hz, 1,734 +/- 281 msec at 20 Hz, 2,993 +/- 661 msec at 25 Hz, and 2,461 +/- 668 msec at 30 Hz during nerve stimulation. Linear regression analysis showed that the response of atrial cycle length to sinoatrial parasympathetic nerve stimulation was frequency dependent. The maximum response and complete decay of the response occurred within 4-8 seconds of initiation or termination of sinoatrial parasympathetic nerve stimulation. Atrioventricular conduction time and the PR interval did not change during sinoatrial parasympathetic nerve stimulation, even when the atria were paced at the baseline heart rate. CONCLUSIONS. Electrical stimulation of parasympathetic nerve fibers in a fat pad near the sinoatrial node increased atrial cycle length without affecting atrioventricular nodal conduction. This is the first study in which such nerve fibers that innervate the sinoatrial node have been selectively stimulated in humans.     

Echocardiography of the Inferior Vena Cava, Superior Vena Cava, and Coronary Sinus in Right Heart Failure

Echocardiographic evaluation of the three major systemic venous channels that drain directly into the right atrium has hitherto received less attention than it deserves. Attention had been paid initially to inferior vena cava dilatation and lack of collapsibility (plethora) as signs of systemic venous congestion. Superior vena cava imaging has not been part of routine echographic evaluation; however, our recent observations on superior vena cava appearance by the right supraclavicular approach provide evidence that dilatation of superior vena cava correlates with that of inferior vena cava as a marker for venous congestion. The coronary sinus caliber, which has been virtually ignored, may also provide echographic signs of systemic congestion, namely, dilatation and lack of normal narrowing during atrial contraction.     

Absent Right Superior Vena Cava with Persistent Left Superior Vena Cava Which Drains to Unroofed Coronary Sinus in a Child with Atrioventricular Septal Defect and Cor Triatriatum Sinister: Preop Correct Diagnosis and Successful Surgery in a Single Session

We report a unique case of a 4‐year‐old boy with intermediate‐type atrioventricular septal defect, cor triatriatum sinister, persistent left superior vena cava, unroofed coronary sinus, and absent right superior vena cava. Persistent left vena cava draining into the unroofed coronary sinus was demonstrated easily using the agitated saline‐contrast echocardiography. After conformation with angiographic evaluation, surgery was performed at a single session. Roofing of the coronary sinus with polytetrafluoroethylene patch, mitral cleft repair, tricuspid annuloplasty, atrioventricular defect repair with pericardial patch, and resection of the membrane in the left atrium was succeeded without complication.     

心房颤动上腔静脉节段性电隔离方法及安全性评估

目的:分析心房颤动(房颤)上腔静脉节段性电隔离的具体手术方法,并评估其安全性.方法:入选2017年11月至2018年9月期间我院阵发性房颤患者50例,患者常规进行肺静脉隔离后,继续行上腔静脉隔离.消融前进行上腔静脉造影,显示上腔静脉与右心房解剖关系,并在CARTO系统运用PentaRay电极导管进行上腔静脉及右心房三维...     

Giant coronary sinus and absent right superior vena cava

Although persistent left superior vena cava (PLSVC) is rare, it is the most common thoracic venous anomaly. The prevalence of PLSVC is 0.3 % in a general population and 10 % in patients with congenital heart disease. Diagnosis of PLSVC is usually incidental during cardiovascular imaging or surgery. Although PLSVC is usually not associated with any negative hemodynamic effect, it is important to be aware of its existence, since it may cause problems in central venous catheterization, pacemaker implantation and cardiopulmonary bypass. The overall proportion of absent right superior vena cava in patients with PLSVC is approximately 20 %. If PLSVC is associated with absence of the right superior vena cava, the coronary sinus may become gigantic due to excessive inflow. Herein, we report a case of PLSVC complicated by the absence of a right superior vena cava resulting in a giant coronary sinus.     

Reopening of a persistent left superior vena cava in the early postoperative period following bidirectional cavopulmonary anastomosis--treatment by coil embolization]

Diagnosis of systemic venous drainage is mandatory for patients with congenital heart disease planned for cavopulmonary anastomosis or any Fontan-type palliation. Preexisting venous channels as the persistent left superior vena cava are common in cardiac anomalies and may lead to postoperative deterioration and cyanosis. We describe a 6 month old boy with a complex imbalanced atrioventricular septal defect who developed cyanosis in the very early postoperative period, following bidirectional cavopulmonary anastomosis. It was caused by ineffective lung perfusion due to a reopened persistent left superior vena cava with drainage to the coronary sinus.He underwent coil embolization of the persistent left superior vena cava with retrievable coils and cyanosis improved. Coil embolization is an effective alternative to secondary surgery, especially for hemodynamically compromised patients in the postoperative period.     

Absent right superior vena cava with left superior vena cava draining to an unroofed coronary sinus

We describe the case of a 1-month-old infant with a complete atrioventricular septal defect with right dominance, situs solitus, and drainage from the persistent left superior vena cava to the coronary sinus. Corrective surgery was carried out without previous cardiac catheterization. During the operation, the right superior vena cava was found to be absent. Cyanosis and head-and-neck edema were observed in the immediate postoperative period. Transthoracic echocardiography carried out after injection of a small volume of stirred saline into an epicranial vein demonstrated the presence of microbubbles in the left cardiac cavities. A second operation was performed to prevent drainage from the left superior vena cava to the left atrium (via the unroofed coronary sinus) and to insert a PTFE conduit between the innominate vein and the right atrial appendage. The outcome was excellent. In this report, the embryological, clinical, diagnostic and therapeutic characteristics of this entity are discussed.