Open Access Medical Books

ATRIAL SEPTAL DEFECT

ATRIAL SEPTAL DEFECT
Edited by P. Syamasundar Rao .

Open Access .
184 pages .

Defects in the atrial septum are one the most common types of congenital heart defects (CHDs) in children and such a defect is the most common CHD in adults. Atrial septal defects (ASDs) cause left to right shunt because the left atrial pressure is higher than that in the right atrium. This causes volume overloading of the right ventricle. While this is generally well tolerated during infancy and childhood, development of exercise intolerance and arrhythmias in later childhood, adolescence and adulthood, and the risk for development of pulmonary vascular obstructive disease in adulthood make  these defects important. The major types of atrial defects are ostium secundum, ostium primum, sinus venosus and coronary sinus ASDs and patent foramen ovale (PFO).
In the first chapter, I review the clinical features and management of ASDs. Patients with small defects are usually asymptomatic while moderate to large defects may present with symptoms. Physical findings include hyperdynamic precordium, widely split and fixed second heart sound, ejection systolic murmur at the left upper sternal border and a mid‐diastolic flow rumble at the left lower sternal border. In patients with ostium primum ASDs, an apical holosystolic murmur may also be heard. Clinical diagnosis is not difficult and the diagnosis can be confirmed and quantified by echocardiographic studies. While surgical intervention was used in the past, transcatheter methods are currently used for closure of ostium secundum ASDs.
Surgical correction is necessary for the ostium primum, sinus venosus and coronary sinus defects. PFO is present in nearly one third of normal population and is likely to be a normal variant and such isolated PFOs do not need intervention. When associated with other CHDs, the PFO facilitates intra‐cardiac shunt to allow appropriate egress and/or mixing of blood flow. Hypoxemia in post‐surgical residual defects including Fontan fenestrations, right ventricular infarction and platypnea‐orthodexia syndrome may be secondary to right to left shunt across PFO and these defects may need closure.
PFO, presumed to be the seat of paradoxical embolism resulting in stroke/transient ischemic attacks is the subject active investigation. Similarly the role of PFO in Caisson’s disease and migraine is not well‐established. There is varying degrees of evidence for benefit of transcatheter occlusion of these PFOs.
In the second chapter, Dr. Balaguru from the University of Texas Medical School, Houston, Texas discusses issues related to ASD in pregnant women. There are remarkable changes in cardiovascular physiology during pregnancy; the cardiac output increases, related to increased stroke volume and heart rate. The systemic vascular resistance decreases; however, concurrent increase in cardiac output keeps blood pressure stable. The blood volume increases (by 1.5 times) by raise in plasma volume; however, this is out of proportion to the increase in red cell mass with consequent relative anemia. These changes are tolerated well because the changes occur gradually. During the third trimester, enlarging uterus compresses the inferior vena cava (IVC) in supine posture leading to decrease in cardiac output and predisposes to deep vein thrombosis. In pregnant women with ASD, there is a greater increase in right atrial and right ventricular size (compared to pregnant women with no heart defect) and a higher incidence of supraventricular tachycardia. The probability of paradoxical embolism via the ASD is high given the predisposition to deep vein thrombosis and hypercoagulable state. If the diagnosis is known prior to  pregnancy and the ASD is large and associated with moderate or severe right heart enlargement and is a potential candidate for supraventricular tachycardia and thromboembolic events during pregnancy, labor or postpartum, the ASD should be closed prior to planned‐pregnancy. Transcatheter or surgical closure could be performed based on the size of the ASD and adequacy of septal rims. When the ASD is diagnosed during pregnancy but, the patient is asymptomatic without functional compromise (NYHA Class I and II) and has no heart failure, atrial arrhythmia, pulmonary hypertension or history of stroke, the these women are likely to do well throughout pregnancy and do not require transcatheter or surgical closure. On the contrary, in the presence of any of these issues, transcatheter or surgical closure may be performed. If transcatheter is opted, second trimester (13‐28 weeks) is preferred 
instead of first trimester to avoid irradiation to the fetus. Local anesthesia with conscious sedation, intracardiac echocardiography to aid balloon sizing and device  deployment and use of long venous sheath; the latter two to avoid or reduces radiation, may be appropriate. If the ASD is unsuitable for transcatheter closure, surgical closure of ASD may be performed in the second trimester with the following precautions: infusion of high‐concentration of glucose (to provide energy for fetus), fetal monitoring, maintenance of high‐flow, high mean arterial pressure (60 mmHg) and high hematocrit (> 25%) and hyper oxygenation. The author concludes that the need for closure of ASD during pregnancy is rare and if possible avoided. When  closure is indicated transcatheter or surgical closure may be performed, taking appropriate precautions .........
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CONTENTS :

Section 1 General Review of Atrial Septal Defects .


 1 Atrial Septal Defect – A Review 3 P. Syamasundar Rao

 2 Pregnancy Issues in Women with Atrial Septal Defect 21 Duraisamy Balaguru


Section 2 Natural History of Atrial Septal Defect .


 3 Prevalence of Secundum Atrial Septal Defect and Associated Findings 31 Mark D. Reller


Section 3 Creation of Atrial Septal Defects .


 4 Computer-Aided Automatic Delivery System of High-Intensity Focused Ultrasound for Creation of an Atrial Septal Defect 39 Hiromasa Yamashita, Gontaro Kitazumi, Keri Kim and Toshio Chiba


Section 4 Transcatheter Closure of Atrial Septal Defect .


 5 Historical Aspects of Transcatheter Occlusion of Atrial Septal Defects 57 Srilatha Alapati and P. Syamasundar Rao

 6 Role of Transesophageal Echocardiography in Transcatheter Occlusion of Atrial Septal Defects 85 Gurur Biliciler-Denktas

 7 Role of Intracardiac Echocardiography (ICE) in Transcatheter Occlusion of Atrial Septal Defects 99 Ismael Gonzalez, Qi-Ling Cao and Ziyad M. Hijazi

Section 5 ASD Closure in Adults and Elderly .

 8 Why, When and How Should Atrial Septal Defects Be Closed in Adults 121 P. Syamasundar Rao

 9 Atrial Septal Defect Closure in Geriatric Patients 139 Teiji Akagi


Section 6 Patent Foramen Ovale .


 10 Atrial Septal Defect/Patent Foramen Ovale and Migraine Headache 155 Mohammed Tawfiq Numan

 11 Transcatheter Occlusion of Atrial Septal Defects for Prevention of Recurrence of Paradoxical Embolism 167 Nicoleta Daraban, Manuel Reyes and Richard W. Smalling

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Published by: younes younes - Sunday, January 20, 2013

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