Patent foramen ovale pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editors-In-Chief: Priyamvada Singh, M.B.B.S. [2]; Assistant Editor-In-Chief: Kristin Feeney, B.S. [3]
Overview
A patent foramen ovale is a flap-like structure in inter-atrial septum that is formed by failure of postnatal fusion of septum primum and septum secundum. It periodically opens and allows blood to shunt between the two atria. Thus, it is also sometimes called as a probe patent (PFO). This flap-like structure functions like a one-way valve mechanism that only opens to allow blood to flow from the right atrium to the left atrium during times where there is an increase flow or pressure in the right atrium. Elevation of pressure in the pulmonary circulatory system (i.e. pulmonary hypertension, cough or valsalva maneuver) can cause the foramen ovale to open.
Pathophysiology
Embryology
Atrial septation begins at about the 4th week of gestation. A crescent-shaped septum primum grows from the primordial atrial roof towards the endocardial cushion and partially divides the common atrium into right and left halves. Formation of the endocardial cushions occurs on the ventral and dorsal walls of the atrioventricular canal. Before the septum pimum reaches the endocardial cushion, programmed cell death occurs in the more cranial part giving rise to perforations that become a large window called the ostium secundum/foramen secundum. Around day 33, a crescent-shaped septum secundum forms on the right side of the septum primum. It grows gradually and overlaps part of the ostium secundum/foramen secundum forming an oval-shaped, incomplete septal partition that becomes the foramen ovale. The foramen ovale allows blood to pass from the right atrium to the left atrium. A flap-like valve is formed by the remaining septum primum over the foramen ovale. Fusion of both septa's occur after birth.[1][2]
Physiology
Pathogenesis
- A foramen ovale is a remnant from the fetal circulation. It may remain patent after birth and through adulthood.[3][4]
- Soon after birth, as an infant takes their first breath, the negative intrathoracic pressure closes the foramen ovale.[5]
- The foramen ovale remains open when the septum primum and septum secundum fail to fuse making the closure incomplete. This patent foramen ovale permits interatrial flow of blood from the right atrium to the left atrium during periods when the right atrial pressure exceeds that of the left atrium. For example, coughing, sneezing or straining.[4][5]
- Patent foramen ovale is undetected in a majority of people and may be seen during cardiac investigation.[5]
Associated Conditions
Conditions associated with patent foramen ovale include:[6]
- Migraine headaches
References
- ↑ Kloesel B, DiNardo JA, Body SC (2016). "Cardiac Embryology and Molecular Mechanisms of Congenital Heart Disease: A Primer for Anesthesiologists". Anesth Analg. 123 (3): 551–69. doi:10.1213/ANE.0000000000001451. PMC 4996372. PMID 27541719.
- ↑ Hara, Hidehiko; Virmani, Renu; Ladich, Elena; Mackey-Bojack, Shannon; Titus, Jack; Reisman, Mark; Gray, William; Nakamura, Masato; Mooney, Michael; Poulose, Anil; Schwartz, Robert S. (2005). "Patent Foramen Ovale: Current Pathology, Pathophysiology, and Clinical Status". Journal of the American College of Cardiology. 46 (9): 1768–1776. doi:10.1016/j.jacc.2005.08.038. ISSN 0735-1097.
- ↑ Morjaria R, Tsaloumas M, Shah P (2015). "An unusual presentation of patent foramen ovale". JRSM Open. 6 (8): 2054270415596320. doi:10.1177/2054270415596320. PMC 4562378. PMID 26380102.
- ↑ 4.0 4.1 Wahl A, Windecker S, Meier B (2001). "Patent foramen ovale: pathophysiology and therapeutic options in symptomatic patients". Minerva Cardioangiol. 49 (6): 403–11. PMID 11733736.
- ↑ 5.0 5.1 5.2 Giblett JP, Abdul-Samad O, Shapiro LM, Rana BS, Calvert PA (2019). "Patent Foramen Ovale Closure in 2019". Interv Cardiol. 14 (1): 34–41. doi:10.15420/icr.2018.33.2. PMC 6406129. PMID 30858890.
- ↑ Yakhkind, A.; Castaldo, J.; Leary, M.C. (2017). "Stroke and Migraine": 570–573. doi:10.1016/B978-0-12-803058-5.00111-9.