Gadolinium-enhanced three-dimensional magnetic resonance angiography of pulmonary and systemic venous anomalies.
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OBJECTIVE: The goal of this study was to evaluate the diagnostic value of gadolinium (Gd)-enhanced three-dimensional (3D) magnetic resonance angiography (MRA) in patients with congenital and acquired anomalies of the pulmonary and systemic veins. BACKGROUND: Gadolinium-enhanced 3D MRA is a fast magnetic resonance imaging technique that has shown great promise in the evaluation of large and medium-sized arteries. However, its application to venous anomalies has not been studied in detail. METHODS: The study retrospectively analyzed all patients who underwent Gd-enhanced 3D MRA examination from January 1998 through January 2001, were diagnosed with anomalies of the pulmonary or systemic veins and had additional diagnostic data available for comparison with the MRA findings. RESULTS: Sixty-one patients (age 1 day to 60 years) were included. Image acquisition was completed in 29 +/- 6.9 s. Pulmonary venous anomalies were found in 37 patients, systemic venous anomalies in 17 patients and both pulmonary and systemic venous anomalies in 7 patients. Compared with available diagnostic information by other modalities, all known or suspected venous anomalies were imaged by 3D MRA. In three patients, catheterization did not detect anomalies of the pulmonary veins that were subsequently diagnosed by MRA. The 3D MRA diagnoses were followed by 10 interventional catheterization procedures and 15 operations. In 74% of patients, 3D MRA either diagnosed previously unsuspected venous anomalies (28%) or added new clinically important information (46%). The mechanism of pulmonary vein compression in eight patients was determined by MRA but not by other imaging modalities. Using a five-level grading system for MRA image quality (1 = nondiagnostic; 5 = excellent), the average grade was 4.6 +/- 0.6, with a 0.28 +/- 0.6 mean grade difference between two independent observers. CONCLUSIONS: Gadolinium-enhanced 3D MRA is capable of rapidly and accurately diagnosing a wide spectrum of pulmonary and systemic venous anomalies and is a useful noninvasive alternative to diagnostic catheterization. (+info)
Infected mediastinitis secondary to perforation of superior vena cava by a central venous catheter.
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We describe the first case of infected mediastinitis associated with central venous catheter insertion. The rare occurrence of this complication may be explained by the fact that it results from central venous catheter-related bloodstream infection and catheter perforation of superior vena cava. The symptoms of this complication (chest pain, dyspnoea) are not specific. Diagnosis should be confirmed by chest x-ray and computerized tomography which show hydromediastinum and pleural effusion. Removal and subsequent culture of the catheter tip will confirm infection. Appropriate antibiotic therapy, guided by sensitivities of the cultured organisms, should be commenced. Any pleural effusion should be drained by thoracocentesis, and the pleural fluid cultured. In case of fever, bacteraemia or shock, a thoracotomy to drain mediastinal and pleural effusions may be considered. (+info)
Flow during exercise in the total cavopulmonary connection measured by magnetic resonance velocity mapping.
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OBJECTIVE: To measure caval and pulmonary flows at rest and immediately after exercise in patients with total cavopulmonary connection (TCPC). DESIGN: An observational study using the patients as their own controls. SETTING: Using a combination of magnetic resonance (MR) phase contrast techniques and an MR compatible bicycle ergometer, blood flow was measured in the superior vena cava, the tunnel from the inferior vena cava, and in the left and right pulmonary arteries during rest and on exercise (0.5 W/kg and 1.0 W/kg). PATIENTS: Eleven patients aged 11.4 (4.6) years (mean (SD)) were studied 6.3 (3.8) years after TCPC operation. MAIN OUTCOME MEASURES: Volume flow measured in all four branches of the TCPC connection during rest and exercise. RESULTS: Systemic venous return (inferior vena cava plus superior vena cava) increased from 2.5 (0.1) l/min/m2 (mean (SEM)) to 4.4 (0.4) l/min/m2 (p < 0.05) during exercise, with even distribution to the two pulmonary arteries. At rest, inferior vena caval flow was higher than superior vena caval flow, at 1.4 (0.1) v 1.1 (0.1) l/min/m2 (p < 0.05). During exercise, inferior vena caval flow doubled (to 3.0 (0.3) l/min/m2) while superior vena caval flow only increased slightly (to 1.4 (0.1) l/min/m2) (p < 0.05). The increased blood flow mainly reflected an increase in heart rate. The inferior vena caval to superior vena caval flow ratio was 1.4 (0.1) at rest and increased to 1.8 (0.1) (p < 0.05) at 0.5 W/kg, and to 2.2 (0.2) at 1.0 W/kg (p < 0.05). CONCLUSIONS: Quantitative flow measurements can be performed immediately after exercise using MR techniques. Supine leg exercise resulted in a more than twofold increase in inferior vena caval flow. This was equally distributed to the two lungs, indicating that pulmonary resistance rather than geometry decides flow distribution in the TCPC circulation. (+info)
Electrophysiology and arrhythmogenic activity of single cardiomyocytes from canine superior vena cava.
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BACKGROUND: The superior vena cava (SVC) has been proved to be a focal point in the initiation of paroxysmal atrial fibrillation. The autonomic nervous system plays an important role in the genesis of atrial fibrillation. However, the arrhythmogenic potentials of SVC and its responses to autonomic agents are not clear. The purpose of this study was to isolate single SVC cardiomyocytes and to investigate their electrophysiological characteristics, as well as the direct effects of autonomic agents. METHODS AND RESULTS: Canine SVC cardiomyocytes were isolated by perfusion with digestive enzymes. The action potentials and ionic currents were investigated in single SVC cardiomyocytes using the whole-cell clamp technique. Dissociation of the SVC yielded rod-shaped single cardiomyocytes with (n=74, 51%) or without (n=71, 49%) pacemaker activities. There were similar densities of inward Ca2+, delayed rectifier K+, transient inward, inward rectifier K+, and pacemaker currents between SVC cardiomyocytes with and without pacemaker activity. SVC cardiomyocytes with pacemaker activity have, however, greater transient outward currents than those without pacemaker activity. In SVC cardiomyocytes, acetylcholine (5.5 micromol/L) abolished the spontaneous activities, but isoproterenol (10 nmol/L), atropine (10 micromol/L), and phenylephrine (10 micromol/L) accelerated the spontaneous activity and induced the occurrences of early or delayed afterdepolarizations. CONCLUSIONS: These findings suggest that SVC cardiomyocytes have distinct action potentials and ionic current profiles that may be responsible for the arrhythmogenic activity of the SVC. (+info)
Thoracic veins and the mechanisms of non-paroxysmal atrial fibrillation.
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OBJECTIVE: The purpose of this article is to review the importance of thoracic veins in the maintenance of sustained (non-paroxysmal) atrial fibrillation (AF). METHODS: Thoracic veins, including the pulmonary veins (PVs), vein of Marshall (VOM) and the superior vena cava (SVC), have muscle sleeves that connect to the atria. It is well known that electrical activities can be recorded within these venous structures. In some incidences, these thoracic veins may serve as the trigger and/or the substrate for paroxysmal AF. The importance of thoracic veins in chronic (sustained) AF is less well appreciated. Therefore, we review the literature to determine if thoracic veins are important in the maintenance of sustained AF. RESULTS: Our recent study demonstrated that repetitive rapid electrical activities are present in the PVs and in the VOM during pacing-induced sustained AF in dogs. Because of these repetitive rapid activities, these thoracic veins have shorter activation cycle lengths than that of the left atrium, which, in turn, has shorter cycle lengths than that of the right atrium. Others have demonstrated that PV isolation in humans can result in a cure of sustained human AF in >80% of patients undergoing concomitant surgery. CONCLUSION: These findings suggest that repetitive rapid activities within the thoracic veins may be responsible for the maintenance of non-paroxysmal (sustained) AF. (+info)
Cor triatriatum sinistrum and persistent left superior vena cava: an original association.
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Cor triatriatum sinistrum is a rare congenital heart disease usually diagnosed in symptomatic children. Symptoms depend on the degree of obstruction to pulmonary venous return with pulmonary hypertension and other associated abnormalities. Persistent left superior vena cava is quite a common congenital heart disease (about 0.5% in healthy populations). It should be suspected every time a dilated coronary sinus is detected at the echo examination. Transthoracic and transoesophageal examinations visualize the site and the size of the fibrous membrane as well as the degree of obstruction, and allow the evaluation of pulmonary pressures that are very important clues for prognosis and therapy. This case report describes the clinical signs and the diagnostic ultrasound findings evaluated in comparison with magnetic resonance imaging, a well-defined gold standard in heart disease of this uncommon congenital association. (+info)
Anomalies of cardiac venous drainage associated with abnormalities of cardiac conduction system.
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The embryological development of the superior vena cava (SVC) is complex. If the left common cardinal vein fails to occlude it can, along with the left duct of Cuvier form a left SVC, which frequently drains into the coronary sinus. This may result in abnormalities in the anatomy of this structure. A persistent left SVC occurs in 0.5% of the normal population, and 3% to 4.3% of patients with congenital heart anomalies. The pacemaking tissue of the heart is derived from two sites near the progenitors of the superior vena cava. The right-sided site forms the sinoatrial node, the left-sided site is normally carried down to an area near the coronary sinus. Out of 300 patients with cardiac rhythm abnormalities, who have undergone electrophysiological studies (EPS), or permanent pacemaker insertion (PPI), we identified 12 patients with cardiac conduction abnormalities and anomalies of venous drainage. Anomalies of the coronary sinus may be associated with abnormalities of the conduction system of the heart. This may be due to the close proximity of the coronary sinus to the final position of the left-sided primitive pacemaking tissue. In our series of 300 patients, 4% had an associated left SVC, a similar incidence to that found in previous studies of congenital heart disease. (+info)
Endothelin-1-induced venous contraction is maintained in DOCA-salt hypertension; studies with receptor agonists.
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1. Deoxycorticosterone acetate (DOCA) salt hypertension is associated with an endothelin-1 (ET-1)-dependent increase in arterial resistance and mean circulatory filling pressure. Contraction of endothelium-intact arteries and veins from sham and DOCA-salt hypertensive rats to agonists of the ET(A) (ET-1((1-31))) and ET(B) receptor (sarafotoxin 6c; S6c) was investigated in tissue baths as was expression of mRNA for ET-1 and mRNA and protein for the ET(A) and ET(B) receptor. 2. ET-1((1-31)) contracted aorta and vena cava from sham rats with a 30 fold lower potency than ET-1. Contraction was not altered by the ET(B) receptor antagonist BQ788 (100 nM) but was abolished by the ET(A) receptor antagonist ABT-627 (30 nM). 3. In DOCA-salt thoracic aorta, maximum contraction to ET-1 and ET-1((1-31)) was reduced (36.6 +/- 6.3 and 13.3 +/- 4.4% of sham response, respectively); aorta did not contract to S6c. 4. In vena cava from DOCA-salt rats, contraction to ET-1 and ET-1((1-31)) was not reduced compared to sham contraction; vena cava from sham and DOCA-salt rats contracted to S6c with a similar potency. 5. Real time RT-PCR revealed that prepro ET-1 mRNA was increased 6.6 +/- 3.3 fold and 8.7 +/- 3.9 fold greater in DOCA-salt aorta and vena cava, respectively, compared to sham. Vena cava expressed a higher content of ET(A) and ET(B) receptor mRNA than aorta (P < 0.05), but no differences were observed between sham and DOCA-salt tissues. ET(A) and ET(B) receptor protein was identified in all tissues. Immunoreactive ET(A) receptor, observed as a 65, 30 and 28 kDa bands, was expressed 400% greater in DOCA-salt aorta compared to sham, but was not altered in vena cava. Immunoreactive ET(B) receptor, observed as 120, 45 and 30 kDa bands, tended to be higher in vena cava compared to aorta, but was not different in sham and DOCA-salt vena cava. 6. These results suggest that ET(A) receptor function is impaired in aorta but not vena cava of DOCA-salt rats. The ET(B) receptor was present in the aorta but, unlike in veins, does not mediate contraction directly. A sustained response to ET-1 in the venous circulation may contribute to the elevated blood pressure in the DOCA-salt model. (+info)