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if Answer3 = RightAnswer3 then
Response.Write " Answer to question n. 3 is right! "
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Response.Write " The right answer is the checked one! "
end if
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The correct answer is "4".
The finding of a patent foramen ovale associated with Chiari's network is quite common, being present in up to 83% of patients with this condition1. In fact, a flow pattern within the right atrium may in part be present in adult life and if the blood flow is preferentially directed from the inferior vena cava toward the fossa ovalis, a patent foramen ovale may persists and the development of an atrial aneurysm may occur1. This association is clinically relevant because of the risk of paradoxic embolism, occurring even in the absence of an apparent peripheral venous source: Chiari's web itself may be the site of thrombosis, by either primary thrombus formation or by entrapment of emboli from peripheral veins1. In our case, we cannot exclude an ischemic stroke by arterial embolism (being not done autopsy study).
Conclusions
Chiari's network was first described in 1897 by Hans Chiari who observed 11 cases in which a network of threads and fibers was found in the right atrium. This network was connected with the Eustachian and Thebesian valves at the orifice of the inferior vena cava and the coronary sinus with wide attachments to the upper region of the right atrium near the crista terminalis, to the interatrial septum or to the tuberculum of Lower1-3.
In early cardiac development, two venous valves guard the right horn of the sinus venosus, which serves, during the embryonic life, to direct the blood flow from the inferior vena cava through the fossa ovalis into the left atrium. The smaller left valve is incorporated into the septum secundum, while the right valve divides the right atrium1-5. In normal development, the right valve regresses, its cephalic portion remaining as the crista terminalis and its caudal part dividing to form the Eustachian and Thebesian valves. Chiari's network represents the congenital remnant of the right valve of the sinus venosus, resulting from incomplete resorption of this structure during the embryonic development2, 3, 5, 6. This condition must be differentiated from a prominent eustachian valve1, 5 and from the condition known as "cor triatriatum dextrum", which derives from the persistence of the entire valve and usually is associated with cyanosis1, 4, 5, 7.
The Chiari's web prevalence has been reported to range from 1.3% to 4% in autopsies studies1, 4, 8, often being an incidental finding at cardiac surgery or post-mortem examination.
It is in fact generally not hemodinamically significant in terms of right atrial obstruction and has been regarded a normal anatomic variant that is seldom of clinical importance1. We suggest that in the case of our patient, this cardiac anomaly was hemodinamically significant, causing a transient obstruction of the right atrium or of the orifice of the inferior vena cava and therefore representing an obstacle to the blood flow into the right atrium. The volume overload of the patient might be a promoter factor causing a higher blood flow coming back to the heart. The position and the wandering feature of the edema might be explained by the highly mobility of the network, with a changeable grade of obstruction of the inferior vena cava orifice or of the right atrium. In our patient, the presence of Chiari's network was not initially suspected, and was an incidental echocardiographic diagnosis performed in order to exclude central venous obstruction.
Nephrologists must be aware of this condition in patients with end-stage renal failure requiring a temporary and urgent vascular access and presenting edema of the upper trunk and of the arms.
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