|Year : 2014 | Volume
| Issue : 2 | Page : 110-112
Atrial septal defect (secundum) with tricuspid regurgitation in a young adult cadaver
Vaishaly K Bharambe1, Neelesh S Kanaskar1, Archana Chirag Buch2, Sapna P Shevade1
1 Department of Anatomy, Dr. D. Y. Patil Medical College, Pimpri, Pune, Maharashtra, India
2 Department of Pathology, Dr. D. Y. Patil Medical College, Pimpri, Pune, Maharashtra, India
|Date of Web Publication||13-Nov-2014|
Dr. Vaishaly K Bharambe
D-9 State Bank Nagar, Panchvati, Pashan Road, Pune - 411 008, Maharashtra
Source of Support: None, Conflict of Interest: None
This report describes a case of a young adult cadaver found to be having atrial septal defect (ASD) of secundum type along with tricuspid regurgitation during routine dissection by medical students. The ASD had a maximum diameter of 8 mm. The report discusses the embryological development of the interatrial septum along with the possible development of this anomaly. The article goes on to discuss the natural history of ASDs of the secundum type, the modes of investigation used today and the significance of socioeconomic status in relation to ASD.
Keywords: Atrial septal defect, ostium secundum, septum primum, septum secundum, tricuspid regurgitation
|How to cite this article:|
Bharambe VK, Kanaskar NS, Buch AC, Shevade SP. Atrial septal defect (secundum) with tricuspid regurgitation in a young adult cadaver. Afr J Med Health Sci 2014;13:110-2
|How to cite this URL:|
Bharambe VK, Kanaskar NS, Buch AC, Shevade SP. Atrial septal defect (secundum) with tricuspid regurgitation in a young adult cadaver. Afr J Med Health Sci [serial online] 2014 [cited 2019 Jan 19];13:110-2. Available from: http://www.ajmhs.org/text.asp?2014/13/2/110/144580
| Introduction|| |
Atrial septal defect (ASD) was first described by Rokitansky in 1875.  Since then many authors have studied ASD from point of view of its occurrence, presentation, possible methods of diagnosis as well as its treatment. , ASDs have been associated with syndromes such as Holt-Oram, Lutembacher, and Down's syndrome.
In the present article, the authors describe a rare finding of ASD of maximum dimension of 8 mm, associated with tricuspid regurgitation (TR) in a cadaver. The article also discusses the embryological development of interatrial septum with the possible explanation for the present finding.
| Case Report|| |
During routine dissection by medical students, the heart of a male formalin fixed cadaver, aged about 40 years, was dissected. The right atrium (RA) was cut open along the right border of the heart. On opening the RA, the interatrial septal wall presented the fossa ovalis with a very thin sickle shaped margin, about 0.5 mm in vertical length, surrounding its upper and anterior edge. Below this sickle shaped margin, the fossa showed the presence of an oval shaped foramen of dimensions 8 mm × 5.5 mm. The foramen communicated the right and left atria. The rest of the interatrial septum appeared intact [Figure 1]a.
|Figure 1: (a) Photograph of cut open right atrium shows the thin sickle shaped margin (A), over the upper margin of fossa ovalis (C) with the atrial septal defect (B) between the two, and the tricuspid valve (D). (b) The photograph of a closer view of the tricuspid valve, showing the expanded septal cusp (E), the dome shaped, bulging anterior (G) and posterior cusps (H), and elongated chordae tendineae (F)|
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The tricuspid ring circumference was 14 cm. The septal cusp of the tricuspid valve was soft, and expanded. The anterior and posterior cusps were dome shaped and bulged into the dilated RA. No vegetations were seen. The chordae tendineae were thin and elongated. Mitral and pulmonary valves were unremarkable. RA and right ventricle were dilated [Figure 1]b.
No variations were observed in rest of the interior of RA, as well as in rest of the heart.
| Discussion|| |
During early development of the heart, the primitive atrium gets divided into right and left atria by development of interatrial septum, which involves the development and fusion of septum intermedium (SI) and septum primum (SP). Perforations in the SP form the ostium secundum (OS). The septum secundum (SS) extends downwards fusing with the left venous valve and septum spurium, its free concave edge overlapping the OS. The right venous valve contributes to the formation of crista terminalis, valve of the inferior vena cava and that of the coronary sinus [Figure 2].
|Figure 2: Diagrams of schematic sections of primitive atrium of heart illustrating successive stages in development of interatrial septum. (I) Development of septum primum (SP). (II) Fusion of SP with septum intermedium (SI) and development of ostium secundum (OS). (III) Development of septum secundum (SS). (IV) Underdeveloped SS in the present case resulting in atrial septal defect (ASD). (a) Septum spurium, (b) right, left venous valves (c) SP, (d) SI, (e) OS, (f) SS, (g) crista terminalis, (h) valve of the inferior vena cava, (i) valve of the coronary sinus, (j) underdeveloped SS, and (k) ASD|
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At birth with the rise of pressure in the left atrium, the SP approximates with the SS with functional fusion followed by structural fusion.  An ASD is a congenital malformation formed due to incomplete development or nonfusion of the above-mentioned embryonic septa.
In the present case, the floor of fossa ovalis represents the SP. The thin upper rim of the fossa ovalis is the underdeveloped SS. Between the two is the ASD representing the OS. Thus, the proposed embryological error responsible for the present ASD is incomplete development of SS [Figure 2].
Atrial septal defect forms 3-8.5% of all congenital heart diseases. OS defect accounts for 60-70% of all cases of ASD with a higher incidence in females. 
Berger states that ASD remains the most underdiagnosed congenital heart disease in adults. While most cases of ASD remain asymptomatic during childhood, as age advances, symptoms begin to appear.  The age at which symptoms appear depends upon the size of the ASD.  The patients show exertional dyspnea, fatigue, palpitation, or atrial tachyarrhythmia's.
It has been found that 37.5% of ASD cases present with symptoms between age of 21 and 30 years. 
Regarding the significance of size of the ASD, an ASD must be at least 10 mm in diameter to carry a significant shunting of blood.  In the present case, the maximum dimension of the ASD was 8 mm.
Tanji et al. reported a case of a 5-year-old girl with ASD of the secundum type associated with TR. The child had developed cardiomegaly and was successfully treated by tricuspid annuloplasty with suture closure of the ASD. 
Tricuspid regurgitation is a rare lesion occurring in <1% of people and is usually asymptomatic. TR is a determinant of the right to left shunt in patients with ASD even in the absence of the reversal of pressure gradient between the left and RA. 
Giamberti et al. discussed the occurrence of functional TR in adults with congenital heart disease.  The present case did not show vegetations on the valves, the cusps were not fibrosed and chordae were not thickened and fused. Other valves were normal, thus ruling out rheumatic etiology and confirming functional TR, probably due to floppy tricuspid valves in association with ASD.
Atrial septal defects are known to be associated with other congenital cardiac lesions such as patent ductus arteriosus, ventricular septal defect, Fallot's tetralogy.  In the present case, the ASD seen was associated with TR.
Atrial septal defects have also been associated with syndromes.  Holt-Oram syndrome shows an ASD with upper extremity anomalies. Lutembacher's syndrome is a combination of mitral stenosis with left to right shunt, usually being an OS ASD.  In the present case, neither mitral stenosis nor any upper extremity anomalies were observed.
Fatema et al. reported a family where mother, son, and daughter had ASDs indicating a clear possibility of genetic inheritance.  ASDs have also been associated with trisomy 21, but in these cases the ASD is predominantly of ostium primum type.  Wilmshurst established that there is a dominant inheritance of ASDs linked to inheritance of migraine with aura. 
A higher incidence of congenital heart disease among children from low socioeconomic status has been observed.  The cadavers at medical colleges are either donated by socially aware individuals or are unclaimed bodies obtained from the coroners (like the present case). Could lack of medical facility, poverty have led to nondetection of this ASD and eventually to the death of this young adult individual? Berger stresses on the need for screening programs to detect all cases suffering from asymptomatic hemodynamically significant ASDs before they reach adulthood and start to develop symptoms. 
Webb and Gatzoulis state that careful physical examination can give an indication of underlying asymptomatic ASD.  Chest radiograph will show cardiomegaly. Venous catheterization of heart with the passage of a catheter from right to left auricle can also be used to demonstrate ASDs. To prove a left to right shunt, blood sample from venae cavae can be compared with those taken from the RA. The level of oxygen content in the atrial blood will be found to be more than that in the venae cavae in case of shunting of blood from left to RA. 
Transthoracic echocardiography is used today for confirmatory diagnosis as well as for pointing to type and size of ASD and direction of shunt. 
| Conclusion|| |
Authors report a case of ASD with associated TR in a young male cadaver. The ASD was found to be of secundum type. Early detection of ASD during its asymptomatic stage in childhood can prevent exacerbation of the condition with advancing age. Study of such cases not only increases awareness of their clinical implications, but also has high educational value for students of embryology.
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[Figure 1], [Figure 2]