The aortic root and the aortic valve (1)

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A Moment in History

William S. Halsted, MD
(1852 – 1922)

American anatomist, teacher, and surgeon, William Stewart Halsted was born in New York City, USA to a wealthy family of English origin. His father was involved in charitable work and Governor and trustee to a city hospital. Not a brilliant student initially, Halsted took an undergraduate in Liberal Arts in Yale, CT., after which he entered the Medical College of Physicians at the Columbia College, where he excelled.

As a second-year medical student Halsted applied and obtained a position in surgery at a local hospital. In here he learned about Lister’s antiseptic technique and became an adamant proponent of it to reduce infection. In 1877 Halsted obtained his MD. After a short time as House Physician at the New York Hospital, Halsted traveled to Europe to further his education studying for two years at the Universities of Vienna, Leipzig, and W?rzburg.

Besides being at the forefront of surgical and antiseptic techniques (introducing the use of rubber gloves in surgery), Halsted was extremely concerned with the way medical students were taught in the US. He pioneered bedside clinical round discussions with the medical students after two years of basic sciences studies. Halsted developed the idea of a patient chart; he also developed the residency program for medical students in use today.

Halsted is probably the most influential researcher and surgeon at the turn of the century. He dedicated time to the study of intestinal anastomoses and the use of silk as a suture material. His experimental work in 1887 proved that the inclusion of the submucosa layer in an anastomosis was mandatory, as well that a single layered anastomosis was enough to attain closure. Perhaps Halsted’s most important contribution was the application and use of the scientific method to surgical questions. Halsted’s principles set the standards used today in surgical suturing and surgical stapling.

He also pioneered the development and surgical techniques for radical mastectomy as a treatment for breast cancer.

As a side effect of this studied in anesthesia and the use of cocaine for anesthesia, Halsted became addicted to this substance, a problem that followed him through the years. Without impairing his capacity as a researcher and a surgeon, Halsted eventually recovered. He died in Baltimore in 1922 as a complication to surgery.

Sources:
1. Dubay, A. D., & Franz, G. M. (2003). Acute Wound Healing: The Biology of Acute Wound Failure. Surg Clin NA, 83, 463-481.
2. Halsted, W. S. (1887). Circular Suture of the Intestine - An Experimental Study. Am J Med Sci, 436-461.
3. “William Stewart Halsted: his life and contributions to surgery” Osborne, P. Lancet Oncol 2007; 8: 256–65
4. “William Stewart Halsted: Surgical pioneer” Burress, P Endoc Today (2010), 8: (2) 22
5. “William Stewart Halsted (1852–1922) Neurological stamp” Haas, LF J Neurol Neurosurg Psych 2000;69:641
Original image courtesy of "Images from the History of Medicine" at www.nih.gov

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Details: Written by: Efrain A. Miranda, Ph.D.; Published: March 15, 2018

Aortic root and aortic valve.
Click for a larger image.

The term “aortic valve” refers to the three leaflets (or cusps) components that allow passage of blood from the left ventricle to the ascending aorta during ventricular systole, while at the same time preventing regurgitation or reflux of blood back into the ventricle during ventricular diastole. In reality, the “valve” is only a component of a larger structure called the “aortic root”. This article will describe the components of the aortic root and the aortic valve.

The ascending aorta presents with two distinct segments. The proximal segment is a dilated portion called the aortic root. The distal portion is known as the tubular portion of the ascending aorta. The boundary between these two portions is the [sinotubular junction (STJ). Some authors will recognize as the ascending aorta only the tubular portion.

The aortic root is that portion of the ventricular outflow tract and proximal aorta that supports the leaflets of the aortic valve. It is a functioning unit with relations both to the to the aorta and to the left ventricle, and it is here where in most cases we find the ostia of the right and left coronary arteries.

The aortic root is composed of the three dilated sinuses of Valsalva, two of which give origin to the coronary arteries (right and left), three leaflets (or cusps), and the interleaflet triangles. While the distal boundary of the aortic root is clearly defined (the STJ), the proximal boundary is not as clear and is difficult to define. The STJ is defined by the apices of the three aortic leaflets as well as a clear line that appears as the aorta passes from the dilations of the sinuses of Valsalva to the well-defined tubular portion of the ascending aorta.

This proximal boundary is defined clinically by two circular regions: the ventriculoaortic ring distally and the virtual basal ring proximally.

The ventriculoaortic ring is a circular region formed by the left ventriculoaortic junction (the point where the aorta anchors on the left ventricle), and fibrous tissue of both the “cardiac skeleton” and the membranous interventricular septum. It is also called the “surgical anulus”. This is the area where a surgeon will anchor an aortic replacement valve.

Continued here: The Aortic Root and the Aortic Valve (2)

Note: The image depicts only one complete aortic leaflet. The other one has been transected to show the sinus of Valsalva and the third has been removed to show the attachment or "hinge" of the leaflet. For an anatomical image of the aortic valve click here.

Sources:
1. The Anatomy of the Aortic Root: Loukas, M et al. Clinical Anatomy 27:748–756 (2014)
2. “Extracardiac aneurysm of the interleaflet triangle above the aortic-mitral curtain due to infective endocarditis of the bicuspid aortic valve.” Hori D, et al. Gen Thorac Cardiovasc Surg. 2008 Aug;56(8):424-6
3. “Anatomy of the aortic root: implications for valve-sparing surgery” Efstratios I. Charitos, HS. Ann Cardiothorac Surg 2013;2(1):53-56
4. “The Forgotten Interleaflet Triangles: A Review of the Surgical Anatomy of the Aortic Valve” Sutton JP, et al Ann Thorac Surg 1995;59:419-27

Image property of: CAA, Inc. Artist: Dr. Miranda

The aortic root and the aortic valve (1)

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