A cardiac shunt is a pattern of blood flow in the heart that deviates from the normal circuit of the circulatory system. It may be described as right-left, left-right or bidirectional, or as systemic-to-pulmonary or pulmonary-to-systemic. The direction may be controlled by left and/or right heartpressure, a biological or artificial heart valve or both. The presence of a shunt may also affect left and/or right heart pressure either beneficially or detrimentally.
The left and right sides of the heart are named from a dorsal view, i.e., looking at the heart from the back or from the perspective of the person whose heart it is. There are four chambers in a heart: an atrium (upper) and a ventricle (lower) on both the left and right sides.[1] In mammals and birds, blood from the body goes to the right side of the heart first.[2] Blood enters the upper right atrium, is pumped down to the right ventricle and from there to the lungs via the pulmonary artery.[3] Blood going to the lungs is called the pulmonary circulation.[4] When the blood returns to the heart from the lungs via the pulmonary vein, it goes to the left side of the heart, entering the upper left atrium. Blood is then pumped to the lower left ventricle and from there out of the heart to the body via the aorta. This is called the systemic circulation. A cardiac shunt is when blood follows a pattern that deviates from the systemic circulation, i.e., from the body to the right atrium, down to the right ventricle, to the lungs, from the lungs to the left atrium, down to the left ventricle and then out of the heart back to the systemic circulation.
A left-to-right shunt is when blood from the left side of the heart goes to the right side of the heart. This can occur either through a hole in the ventricular or atrial septum that divides the left and the right heart or through a hole in the walls of the arteries leaving the heart, called great vessels. Left-to-right shunts occur when the systolic blood pressure in the left heart is higher than the right heart, which is the normal condition in birds and mammals.
Congenital shunts in humansedit
The most common congenital heart defects (CHDs) which cause shunting are atrial septal defects (ASD), patent foramen ovale (PFO), ventricular septal defects (VSD), and patent ductus arteriosi (PDA). In isolation, these defects may be asymptomatic, or they may produce symptoms which can range from mild to severe, and which can either have an acute or a delayed onset. However, these shunts are often present in combination with other defects; in these cases, they may still be asymptomatic, mild or severe, acute or delayed, but they may also work to counteract the negative symptoms caused by another defect (as with d-Transposition of the great arteries).
where is the pulmonary vein, is the pulmonary artery, is the systemic arterial, and is the mixed-venous The Qp:Qs ratio is based upon the Fick principle and it is reduced to the above equation and eliminates the need to know cardiac output and hemoglobin concentration.
All reptiles have the capacity for cardiac shunts.[5]
Referencesedit
^National Library of Medicine, National Institutes of Health, Dugdale DC, Zieve D, Chen MA, Ogilvie I, A.D.A.M. editorial team (June 3, 2012). "Heart chambers". nlm.nih.gov.
^Carl Bianco; Montana State University (May 15, 2013). . montana.edu. Archived from the original on 2013-05-16.
^Cleveland Clinic (2013). "How Does Blood Flow Through the Heart?". clevelandclinic.org.
^Hicks, James (2002). "The Physiological and Evolutionary Significance of Cardiovascular Shunting Patterns in Reptiles". News in Physiological Sciences. 17 (6): 241–245. doi:10.1152/nips.01397.2002. PMID 12433978.
April 27, 2024
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A cardiac shunt is a pattern of blood flow in the heart that deviates from the normal circuit of the circulatory system It may be described as right left left right or bidirectional or as systemic to pulmonary or pulmonary to systemic The direction may be controlled by left and or right heart pressure a biological or artificial heart valve or both The presence of a shunt may also affect left and or right heart pressure either beneficially or detrimentally Contents 1 Terminology 2 Congenital shunts in humans 3 Acquired shunts in human 3 1 Biological 3 2 Mechanical 4 Reptile 5 ReferencesTerminology edit nbsp Atrial septal defect with left to right shunt The left and right sides of the heart are named from a dorsal view i e looking at the heart from the back or from the perspective of the person whose heart it is There are four chambers in a heart an atrium upper and a ventricle lower on both the left and right sides 1 In mammals and birds blood from the body goes to the right side of the heart first 2 Blood enters the upper right atrium is pumped down to the right ventricle and from there to the lungs via the pulmonary artery 3 Blood going to the lungs is called the pulmonary circulation 4 When the blood returns to the heart from the lungs via the pulmonary vein it goes to the left side of the heart entering the upper left atrium Blood is then pumped to the lower left ventricle and from there out of the heart to the body via the aorta This is called the systemic circulation A cardiac shunt is when blood follows a pattern that deviates from the systemic circulation i e from the body to the right atrium down to the right ventricle to the lungs from the lungs to the left atrium down to the left ventricle and then out of the heart back to the systemic circulation A left to right shunt is when blood from the left side of the heart goes to the right side of the heart This can occur either through a hole in the ventricular or atrial septum that divides the left and the right heart or through a hole in the walls of the arteries leaving the heart called great vessels Left to right shunts occur when the systolic blood pressure in the left heart is higher than the right heart which is the normal condition in birds and mammals Congenital shunts in humans editThe most common congenital heart defects CHDs which cause shunting are atrial septal defects ASD patent foramen ovale PFO ventricular septal defects VSD and patent ductus arteriosi PDA In isolation these defects may be asymptomatic or they may produce symptoms which can range from mild to severe and which can either have an acute or a delayed onset However these shunts are often present in combination with other defects in these cases they may still be asymptomatic mild or severe acute or delayed but they may also work to counteract the negative symptoms caused by another defect as with d Transposition of the great arteries Acquired shunts in human editBiological edit Some acquired shunts are modifications of congenital ones a balloon septostomy can enlarge a foramen ovale if performed on a newborn PFO or ASD or prostaglandin can be administered to a newborn to prevent the ductus arteriosus from closing Biological tissues may also be used to construct artificial passages Evaluation can be done during a cardiac catheterization with a shunt run by taking blood samples from superior vena cava SVC inferior vena cava IVC right atrium right ventricle pulmonary artery and system arterial Abrupt increases in oxygen saturation support a left to right shunt and lower than normal systemic arterial oxygen saturation supports a right to left shunt Samples from the SVC amp IVC are used to calculate mixed venous oxygen saturation using the Flamm formula S v O 2 3 4 S V C 1 4 I V C displaystyle S v O 2 frac 3 4 times SVC frac 1 4 times IVC nbsp and Qp Qs ratio Q p Q s change in oxygen concentration across the pulmonary circulation change in oxygen concentration across the systemic circulation P V P A S A S V displaystyle Qp Qs frac text change in oxygen concentration across the pulmonary circulation text change in oxygen concentration across the systemic circulation frac P V P A S A S V nbsp where P V displaystyle P V nbsp is the pulmonary vein P A displaystyle P A nbsp is the pulmonary artery S A displaystyle S A nbsp is the systemic arterial and S V displaystyle S V nbsp is the mixed venous The Qp Qs ratio is based upon the Fick principle and it is reduced to the above equation and eliminates the need to know cardiac output and hemoglobin concentration Mechanical edit Mechanical shunts such as the Blalock Taussig shunt are used in some cases of CHD to control blood flow or blood pressure Reptile editSee also Reptile Circulation All reptiles have the capacity for cardiac shunts 5 References edit National Library of Medicine National Institutes of Health Dugdale DC Zieve D Chen MA Ogilvie I A D A M editorial team June 3 2012 Heart chambers nlm nih gov Carl Bianco Montana State University May 15 2013 How Your Heart Works montana edu Archived from the original on 2013 05 16 Cleveland Clinic 2013 How Does Blood Flow Through the Heart clevelandclinic org The Franklin Institute May 15 2013 Body Systems Pulmonary Circulation It s All in the Lungs fi edu Archived from the original on 2013 05 05 Hicks James 2002 The Physiological and Evolutionary Significance of Cardiovascular Shunting Patterns in Reptiles News in Physiological Sciences 17 6 241 245 doi 10 1152 nips 01397 2002 PMID 12433978 Retrieved from https en wikipedia org w index php title Cardiac shunt amp oldid 1148988186, wikipedia, wiki, book, books, library,
