Electroanatomic mapping and catheter ablation of breakthroughs from the right atrium to the superior vena cava in patients with atrial fibrillation.
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BACKGROUND: The superior vena cava (SVC) is one of the sources of ectopies that can initiate atrial fibrillation (AF). We investigated by radiofrequency ablation the electrophysiological characteristics of the junction of the right atrium (RA) and the SVC and the feasibility of electrical disconnection of the SVC from the RA. METHODS AND RESULTS: Sixteen patients with paroxysmal AF after pulmonary vein isolation underwent electroanatomic mapping at the RA-SVC junction during sinus rhythm. Mapping showed sharp potentials (SVC potentials) inside the SVC. Activation spread from the earliest SVC potential (breakthrough) to the rest of the SVC. SVC potentials were found over a large amount of the circumference, suggesting widespread muscle coverage of the SVC. Breakthroughs from the RA to SVC were located anteriorly, laterally, posteriorly, and septally in 3, 4, 10, and 6 patients, respectively. The number of breakthroughs was 1.4+/-0.5 per patient. Radiofrequency energy was applied with the end point of electrical disconnection. All breakthroughs were eliminated with 3.1+/-1.7 applications per breakthrough without complications. CONCLUSIONS: SVC potentials can be recorded inside the SVC. There are specific breakthroughs from the RA to the SVC that can be identified by electroanatomic mapping. The electrical disconnection of the SVC from the RA is feasible. (+info)
The terminal crest: morphological features relevant to electrophysiology.
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OBJECTIVE: To investigate the detailed anatomy of the terminal crest (crista terminalis) and its junctional regions with the pectinate muscles and intercaval area to provide the yardstick for structural normality. DESIGN: 97 human necropsy hearts were studied from patients who were not known to have medical histories of atrial arrhythmias. The dimensions of the terminal crest were measured in width and thickness from epicardium to endocardium, at the four points known to be chosen as sites of ablation. RESULTS: The pectinate muscles originating from the crest and extending along the wall of the appendage towards the vestibule of the tricuspid valve had a non-uniform trabecular pattern in 80% of hearts. Fine structure of the terminal crest studied using light and scanning electron microscopy consisted of much thicker and more numerous fibrous sheaths of endomysium with increasing age of the patient. 36 specimens of 45 (80%) specimens studied by electron microscopy had a predominantly uniform longitudinal arrangement of myocardial fibres within the terminal crest. In contrast, in all specimens, the junctional areas of the terminal crest with the pectinate muscles and with the intercaval area had crossing and non-uniform architecture of myofibres. CONCLUSIONS: The normal anatomy of the muscle fibres and connective tissue in the junctional area of the terminal crest/pectinate muscles and terminal crest/intercaval bundle favours non-uniform anisotropic properties. (+info)
Electrocardiogram of secumdum type atrial septal defect simulating endocardial cushion defect.
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Three groups of patients are identified in the series of secumdum atrial septal defect with left axis deviation in an analysis of 910 patients of secundum atrial septal defect with or without other accompanying anomalies: 1) 12 patients with isolated ostium secumdum defect; 2) 5 patients with associated prolapse of posterior leaflet of the mitral valve; 3) 4 patients with associated hypertrophic cardiomyopathy and/or single (left) coronary artery. The findings of these 21 patients with proved secumdum atrial septal defect are analysed. The combination of such anomalies should be considered in the differential diagnosis of primum endocardial cushion defect from the electrocardiographic viewpoints. (+info)
Rat model of pulmonary arteriovenous malformations after right superior cavopulmonary anastomosis.
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We developed a rat model of pulmonary arteriovenous malformations after cavopulmonary anastomosis. We sought to determine whether this model reproduces the angiographic and histologic features seen in the human condition. Eight Sprague-Dawley rats underwent a right superior cavopulmonary anastomosis with the use of microsurgical techniques. Between 2 and 13 mo, pulmonary angiography was performed, the animals were euthanized, and the lungs were removed. Microscopic sections of the lung were stained with an endothelial-specific antibody (von Willebrand factor). Microvessel density was determined by counting vessels staining positively for von Willebrand factor, and the shunted and nonshunted (control) lungs were compared for each animal. Pulmonary angiography revealed time-dependent development of arteriovenous malformations. Microvessel density demonstrated a time-dependent increase in the shunted lung compared with the control lung (simple linear regression of the ratio of the microvessel density of the shunted lung divided by the microvessel density of the control lung on time; R(2) = 0.79, P = 0.003). This animal model reproduces the same angiographic and microscopic features of pulmonary arteriovenous malformations that develop in humans after cavopulmonary anastomosis. This appears to be a valid model that may be used to further study etiologic mechanisms for this phenomenon. (+info)
Which to measure, systemic or organ blood flow? Middle cerebral artery and superior vena cava flow in very preterm infants.
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AIM: To describe, in very preterm babies, postnatal changes in measures of middle cerebral artery (MCA) Doppler variables. To relate these peripheral measures to echocardiographic measures of systemic blood flow and ductal shunting, and to study their relation to subsequent intraventricular haemorrhage (IVH). METHODS: 126 babies born before 30 weeks were studied with serial echocardiography and cerebral and Doppler ultrasound of the MCA at 5, 12, 24, and 48 hours of age. Echocardiographic measures included superior vena cava (SVC) flow and colour Doppler diameter of the ductal shunt. MCA Doppler measures included mean velocity, pulsatility index (PI), and estimated colour Doppler diameter. RESULTS: MCA mean velocity increased whereas the PI decreased significantly over the first 48 hours. Babies with low SVC flow had significantly lower MCA mean velocity and estimated diameter than babies with normal SVC flow. There was no difference in PI. On multivariant analysis, the significant associations with MCA mean velocity were mean blood pressure (MBP), heart rate, SVC flow, and lower calculated vascular resistance. The significant associations with PI were larger ductal diameter and lower mean MBP. The significant associations with MCA diameter were higher SVC flow and lower calculated vascular resistance. After controlling for gestation, there was a highly significant association between lowest SVC flow and subsequent IVH but no association between IVH and lowest MCA mean velocity, estimated diameter, PI, or MBP. CONCLUSIONS: These data are consistent with the speculation that SVC flow is a reflection of cerebral blood flow. Low SVC flow is more strongly associated with subsequent IVH than cerebral artery Doppler measures or MBP. (+info)
Surgical experience with right atrial-aortic fistula and penetration of the superior vena cava by a protruding Accufix atrial J-shaped retention wire.
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A 57-year-old woman who had a dual chamber pacemaker implanted in June 1990 for sick sinus syndrome had developed heart failure since 1993. Although fluoroscopy revealed that the proximal J-shaped retention wire of the lead had fractured and had protruded through the outer insulation in 1994, and also that the distal J-shaped retention wire of the lead had protruded through the outer insulation in 1997, a transthoracic echocardiographic examination diagnosed tricuspid valve regurgitation, suggesting that the right atrial-aortic fistula might have been overlooked. In an attempt to avoid migration of the J-shaped retention wire from the lead and to repair the tricuspid regurgitation, it was decided that an operation be performed; however, intraoperative transesophageal echocardiography showed a right atrial-aortic fistula. Intraoperative inspection also revealed that the right atrial-aortic fistula and penetration of the superior vena cava had been caused by the Accufix atrial J-shaped retention wire. Under total cardiopulmonary bypass and induced cardiac arrest, a right atriotomy was performed and the atrial and ventricular leads were removed from the tips. The atrial orifice of the fistula and the aortic orifice were closed. Finally, a new dual-chamber pacing system with bipolar epicardial pacing leads was implanted. Postoperative inspection revealed that the proximal retention wire had fractured, the tip of the retention wire had protruded through the outer insulation, and the distal J-shaped outer insulation was damaged. (+info)
Azygous vein to right atrium bypass graft in a patient with idiopathic fibrosing mediastinitis and symptomatic superior and inferior vena cava obstructions.
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We report an unusual case of a patient with diminished cardiac output caused by systemic venous occlusions of unclear etiology with a history of idiopathic fibrosing mediastinitis and retroperitoneal fibrosis. On thoracic, abdominal, and pelvic venograms, the patient was previously known to have superior vena caval and infrarenal inferior vena caval occlusions. Subsequent studies revealed retrograde flow through the azygous and hemiazygous veins and numerous caval-portal anastomoses providing venous return from the upper and lower extremities. After an extensive hypercoagulable state work-up, no abnormalities were found. To relieve the symptoms, the patient underwent an elective right thoracotomy with azygous vein to right atrial bypass graft. The patient has had complete amelioration of the disabling symptoms and participates in many activities that he could not tolerate previously. Because this condition and procedure are unreported, we present a novel surgical treatment option to palliate symptoms caused by concurrent superior and inferior caval obstructions by improving venous return to the heart. (+info)
Sinus venosus syndrome: atrial septal defect or anomalous venous connection? A multiplane transoesophageal approach.
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OBJECTIVE: To discuss the anatomical features of sinus venosus atrial defect on the basis of a comprehensive transoesophageal echocardiography (TOE) examination and its relation to surgical data. METHODS: 24 patients (13 men, 11 women, mean (SD) age 37 (17) years, range 17-73 years) with a posterior interatrial communication closely related to the entrance of the superior (SVC) or inferior vena cava (IVC) who underwent TOE before surgical repair. Records of these patients were retrospectively reviewed and compared with surgical assessments. RESULTS: In 13 patients, TOE showed a deficiency in the extraseptal wall that normally separates the left atrium and right upper pulmonary vein from the SVC and right atrium. This deficiency unroofed the right upper pulmonary vein, compelling it to drain into the SVC, which overrode the intact atrial septum. In three patients, TOE examination showed a defect in the wall of the IVC, which continued directly into the posterior border of the left atrium. Thus, the intact muscular border of the atrial septum was overridden by the mouth of the IVC, which presented a biatrial connection. In the remaining eight patients, the defect was located in the muscular posterior border of the fossa ovalis. A residuum of atrial septum was visualised in the superior margin of the defect. Neither caval vein overriding nor anomalous pulmonary vein drainage was present. CONCLUSIONS: Sinus venosus syndrome should be regarded as an anomalous venous connection with an interatrial communication outside the confines of the atrial septum, in the unfolding wall that normally separates the left atrium from either caval vein. It results in overriding of the caval veins across the intact atrial septum and partial pulmonary vein anomalous drainage. It should be differentiated from posterior atrial septal defect without overriding or anomalous venous connections. (+info)