tetralogy

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tetralogy

 [tet-ral´ah-je]
a group or series of four.
tetralogy of Fallot a congenital heart defect that combines four structural anomalies: obstruction to pulmonary flow; ventricular septal defect (abnormal opening between the right and left ventricles); dextroposition of the aorta (aortic opening overriding the septum and receiving blood from both ventricles); and right ventricular hypertrophy (increase of volume of the myocardium of the right ventricle).



Infants with this condition are sometimes referred to as blue babies because of the presence of cyanosis, an outstanding symptom. This is due to mixing of poorly oxygenated blood from the systemic circulation with oxygenated blood from the lungs, because of the position of the aorta. Other symptoms include clubbing of the ends of the fingers, hemoptysis, dyspnea on exertion, and a slight delay in growth and development.

Diagnosis is confirmed by electrocardiography, angiocardiography, and cardiac catheterization. These procedures demonstrate changes in the heart's electric impulses; defects in the ventricles, aorta, and pulmonary artery; and, from samplings of blood taken from the various chambers of the heart and great vessels, the oxygen content and pressure of the blood in these various areas.

Treatment involves surgical correction whenever possible. Without corrective surgery the prognosis is extremely poor for children who are deeply cyanotic and have dyspnea on slight exertion.

Before surgery, medical treatment is necessary to avoid complications and control dyspneic attacks. Since the hematocrit is high and polycythemia is common, efforts must be made to prevent dehydration and avoid the development of thrombi. Paroxysmal dyspnea, which often follows feeding or a spell of crying, usually can be relieved by placing the infant in knee-chest position, administering oxygen, or administering a mild sedative or morphine.

Surgical procedures for correction of the defects in the heart and great vessels vary according to the severity of symptoms and the age of the patient. In some cases an anastomosis of the arteries may be done as a temporary measure until more extensive surgery is feasible. In most cases open heart surgery is most successful in relieving symptoms and produces the most lasting benefits.
Tetralogy of Fallot. The right ventricular outflow tract obstruction results in blood flowing from right to left across the ventricular septal defect. From Lissauer and Graham, 2002.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

tet·rad

(tet'rad),
1. A collection of four things having something in common, such as a deformity with four features, for example, Fallot tetralogy. Synonym(s): tetralogy
2. In chemistry, a quadrivalent element.
3. In heredity, a bivalent chromosome that divides into four chromatids during meiosis.
[G. tetras (tetrad-), the number four]
Farlex Partner Medical Dictionary © Farlex 2012

tetralogy

(tĕ-trăl′ə-jē, -trŏl′-)
n. pl. tetralo·gies
1. A series of four related dramatic, operatic, or literary works.
2. Medicine A complex of four symptoms.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

tet·rad

(tet'rad)
1. A group of four things having something in common, such as a deformity with four features, e.g., Fallot tetralogy.
Synonym(s): tetralogy.
2. chemistry A quadrivalent element.
3. genetics A bivalent chromosome that divides into four during meiosis.
[G. tetras (tetrad-), the number four]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
References in periodicals archive ?
Given the importance of paradox in early Greek prose, and given the fondness of other sophists for it, would it not be natural for Antiphon to employ paradox in the Tetralogies to challenge the reigning doxa of legal argumentation in the same way that philosophers and sophists had challenged the reigning doxa concerning the natural world?
"The Tetralogies ascribed to Antiphon." Transaction of the American Philological Society, 114, 71-85.
21-39) but it has now also been used to describe the universe of earlier demonstration orations, and the Tetralogies in particular (see Innes, 1991, and Gagarin 2002, p.
(5) A great deal of scholarship has been devoted to hashing out the question of the authorship of the Tetralogies. The esteemed German scholar of Attic oratory Friedrich Blass inclined toward the position that the Tetralogies were genuinely Antiphonian in Die attisch Beredsamkeit (1887).