SIZE

The Common Vein Copyright 2008

Introduction

The aorta is an elastic artery originating at the aortic opening of the heart’s left ventricle.  It is similar in size tothe main pulmonary artery, just slightly smaller to the the anteriposterior dimension of the left atrium

Size

In the normal adult the aorta has a diameter of about 3 cm, tapering to approximately 1.75 cm as it bifurcates into the common iliac arteries opposite the fourth lumbar vertebra.  However, these measurements will be reduced in female patients, as women have smaller aortas than men, even when they have the same body mass and surface area.

Physiological Changes

In an average lifetime the heart beats more than two and a half billion times, and the aorta distends and relaxes ….s.

Under basal conditions the stroke volume in a 70kg man is 70ccs/beat.

The normal cardiac output under resting conditions is 5-6 litres /minute.  That means that in the average person 7200-8640 liters of blood are pumped through the heart per day.  The figures are even more staggering over a lifetime – 2.1 x 10⁸-2.5 x 10⁸ liters of blood pumped through the heart over the average lifespan of 79 years.

Add excercise – what happens to heart rate and stroke volume

Make sure you provide a reference for your work on each document using journals and  or text The Grays on line is old so if possible use new ones – remember I have the student consult and can order some relevant texts when you find appropriate and reliable texts

Also remember the first go around we want to populate with big picture in mind  and second go around we will atend to the detail of parts and sizes and applied biology as for example after tthe first image

Changes with Time

Over time both the diameter and length of the aorta change.  Beginning at age 50-60 the aorta’s diameter increases approximately 1 mm per year, as it loses elasticity.  Longitudinal growth of the aorta also occurs, particularly in patients suffering from abdominal aortic aneurysms.  Longitudinal growth is also part of the normal growth process but is accelerated in some patients who have a predisposition for aneurysmal disease. The ratio of ascending to descending aorta, which is normally about 3:2, also changes over time, as beyond the age of 55 the descending aorta enlarges to a greater degree than the ascending aorta.

 

Gradual Size Changes in the Aorta From Proximal to Distal

72871.800 aorta thorax abdomen arch ascending descending abdominal progressive and gradual size change ductus diverticulum normal anatomy CTscan Courtesy Ashley Davidoff MD

Ascending Aorta

Annulus

The annulus is approximately 3-3.5 cm

Sinuses

The diameter of the bulbous portion is about 3-3.7cms as well

Tubular Portion

Ascending aorta -usually measures in the 2 – 3.7 cm in diameter. In young males the tubular portion of the ascending aorta measures approximately 33 mm (30- 35mm) and the descending aorta 23 mm. (21- 25mm) The size in young females is slightly less. The ascending aorta and the MPA should be about the same size. The A-P dimension of the left atrium should be about the same size as the ascending aorta. The ratio of ascending to descending aorta should normally be about 3:2 Over 55 the descending aorta enlarges to hgreater degree than the ascending aorta and thus this ratio changes. Women have slightly smaller aortas than men, even at the same body surface area. The right pulmonary artery is a useful standard axial landmark for measuring the ascending aorta. The measurement is usually made in the transverse plane (peprendicular to the long axis) and at a position where the cut is a transverse.

Aorta and Pulmonary Artery –  Normal Size and Position

27467c01 aorta pulmonary valve pulmonary artery SVC size position normal CTscan Davidoff MD

Aorta to Pulmonary Artery Ratio

34769c07b02  heart cardiac aortic valve pulmonary valve conus infundibulum RVOT right ventricular outflow tract pulmonary artery normal size aorta to PA ratio aorta to LA ratio anatomy CTscan Davidoff MD

Normal (a,c) and Aortic Stenosis with Post Stenotic Dilatation (b,d)

07969c06 heart aorta left ventricle LV normal anatomy fx hypercontractile ballet slipper ejection fraction = 80% AV aortic valve thickened doming ejection click jet turbulence shear stress post stenotic dilalation dilitation LV angiogram angiography Courtesy Ashley Davidoff MD aortic valve 07969c03 07969c02 07969c04

Aortic Arch

The arch measures about 2.5-3cms

Isthmus

At the isthmus the aorta narrows by about 3mm. The isthmus defines the attachment of the ligamentum arteriosum to the aorta as well as delineating the arch from the descending aorta.

Descending Thoracic Aorta

The descending thoracic artery starts after the LSA at the level of the isthmus and terminates at the aortic hiatus. It measures between 2 and 2.5 cms, with little difference between the proximal and distal measurement, since the branches it gives off are relatively small. The abdominal aorta has a suprprenal component and an infrarenal component.

Abdominal Aorta

There is progressive narrowing of the aorta from the aortic hiatus where it measures between 2 and 2.5cms at the hiatus and between 1.75cms and 2cms at the bifurcation.  The caliber of the abdominal aorta diminishes as it runs inferiorly, since its branches are large.

Normal Abdominal Aorta

This is an angiogram of a normal abdominal aorta. It consists of a suprarenal and an infrarenal component separated by the origin of the renal arteries. See image 24877d for color overlay. Courtesy Ashley Davidoff MD. 24877b

Applied Biology

Disease at the Sinotubular Junction

Supravalvar Aortic Stenosis – William’s Syndrome

Enlarged Aorta – Ascending Aortic Aneurysm

42358.800 aorta fx enlarged MPA pulmonary artery aneurysm of the ascending aorta CTscan Davidoff MD

Normal Aorta and Enlarged Pulmonary Artery

42315.800 aorta pulmonary artery enlarged MPA dilated dx PDA patent ductus arteriosus CTscan Davidoff MD

 

Ascending Aortic Aneurysm

This series of images are from a CTscan showing an ascending aortic thoracic aneurysm. There is evidence of heavy calcification of the aortic valve (aortic sclerosis), an aneurysm confined to the ascending aorta (b,c,d), and tortuosity of the descending aorta (d). The cause for the aneurysm is probably a combination of systemic hypertension, aortic stenosis and atherosclerotic degeneration of the wall. Courtesy Ashley Davidoff MD 19426c

Atresias and Hypoplasia – Congenital Disorders

Hypoplastic Ascending Aorta and Aortic Arch in Patient with Hypoplastic Left HEart Syndrome, Patent Ductus Arteriosus

00252 newborn CHD heart ascending aorta pulmonary artery ductus arteriosus hypoplastic aortic arch dx hypoplastic left heart syndrome enlarged right venticle coarctation PDA ptent ductus arteriosus grosspathology Davidoff MD

Hypoplastic Ascending Aorta and Hypoplastic Arch

This pathologic specimen shows a small ascending aorta, and arch with a diffuse coarctation. with a large pulmonary artery (purple overlay in b) and a patent ductus arteriosus (green overlay in b)Courtesy Ashley Davidoff MD 00264c code heart cardiac hypoplastic aortic arch PDA coarctation of the aorta AO congenital grosspathology 00269b02 heart cardiac coronary artery aorta small dx aortic atresia tubular hypoplasia aortic coarctation aortic atresia PDA patent ductus arteriosus angiogram angiogaphy CHD congenital heart disease Davidoff MD 00269b01 00269b02 00269b03

Takayasu’s Arteritis

Smooth Narrowing – Takayasu’s Aortitis

20354b01 14 year old male artery thoracic aorta fx smooth narrowing of isthmus of aorta Takayasu’s aortitis angiography angiogram Courtesy Ashley Davidoff MD

 

Descending Aorta

 

Abdominal Aorta

Infrarenal Abdominal Aortic Aneurysm

The digitally subtracted angiogram shows a fusiform infrarenal abdominal aortic aneurysm. There is mild ectasia of the right common iliac artery. Courtesy Ashley Davidoff MD 24590

Aneurysm of the Abdominal Aorta

This angiogram of the abdominal aorta shows a widened infrarenal aorta. At first glance the lumen of the aorta appears normal, but a faint curvilinar calcification of the true wall can be seen to the patients left in the first image. The second image (b) reveals the true size of the aneurysm. Courtesy Ashley Davidoff MD 22734 cW02 codeCVS aorta artery abdomen aneurysm AAA

 

AAA 7.4cms –  Indications for Surgical Intervention

2055BH~1.c01 abdomen aorta abdominal aorta AAA aneurysm thrombus 7.5cms surgical size Courtesy Philips Medical Systems

Smooth Narrowing of the Lumen Due to Aneurysmal Disease

This angiogram of the abdominal aorta (a) and iliac arteries (b), shows an unusually straight and narrowed infrarenal aorta indicative of thrombus in the wall of an abdominal aortic aneurysm. In addition there is an aneurysm of the right common iliac artery and a subtotal occlusion of the left common iliac artery. Note the left kidney is small and there is a wedge shaped defect in the upper and lateral aspect of the kidney indicative of an infarct, probably embolic in origin. Courtesy Laura Feldman MD. 36005c code abdominal aorta aneurysm artery iliac stenosis occlusion kidney infarct wedge embolus

Normal and Ruptured Aorta

37004 abdomen aorta kidneys cortical phase subcurtaneous fat adipose tissue normal anatomy gallsones cholelthiasis CT scan Davidoff MD 18269 aorta abdomen AAA aortic aneurysm abdominal aorta retroperitoneum fx retroperitoneal hematoma fx active hemorrhage fx perinephric hematoma anterior pararenal space perirenal space posterior pararenal space hemorrhage dx rupture abdominal aortic aneurysm CTscan Davidoff MD fx ruptured AAA

Shock and the small Aorta

This patient presents with cardiogenic shock In image a, the right ventricle and right atrium are enlarged and thereare bilateral pleura; effusions. Image b shows stasis of contrast into the IVC and the column is relatively stattic due to peripheral constriction and slow return. There is reflux into the hepatic veins due to tricuspid regurgitation and the reflux extnds all the way to the periphery indicating poor forward flow in the hepatic circulaltion again due to operipheral constriction. Note how small the aorta due to contraction of the muscular media in this life threatening situation.. In image c the celiac axis with branches hepatic artery and splenic artery show severe vasoconstriction. In d the reflux of contrast from tricuspid regurgitaion (TR)extends deep into the renal parenchyma for the reasons outlined above.   The patient subsequently developed shocked liver. 73796c01 Courtesy Ashley Davidoff MD

Normal and Contracted

73796c02 Normal patient (a) and patient with cardiogenic shock In image b. Note the difference in size of the aorta on the left and the contracted aortaon the right. Note how small the aorta due to contraction of the muscular media in this life threatening situation.. I heart circulation aorta small shock CTscan Courtesy Ashley Davidoff MD

Lymphoma Surrounding a Small Atherosclerotic Aorta

Large Lymphmatous Deposit around a Small Atherosclerotic Aorta

This cross sectional image of the mid abdmen shows an aorta with an expanded diameter, which in this case is associated with an extremely small lumen. Note the wall of atherosclerotic calcification is on the inside of the soft tissue surrounding it. The case represents non-Hodgkins abdominal lymphoma that masquerades as an abdominal aortic aneurysm. The positioning of the calcification is key to this recognition. Courtesy Ashley Davidoff MD 15657 code CVS aorta large lyphoma radiologists and detectives

Inflammatory Disorders

Takayasu’s Arterirtis

The series of images are from the angiogram of a 14 year old female who presented with seizures and an elevated blood pressure. Images a and b show multiple stenoses within the carotids best seen at the level of the bifurcation into external and internal arteries. In addition in b, the aortic arch shows non critical narrowing just after the origin of the left common carotid vessel. Note that the right subclavian artery is not seen and presumably is accluded at its origin. The abdominal angiogram shows a significant narrowing of the left renal artery with post stenotic dilitation, and stenotic disease in the infrarenal abdominal aorta. The multicentric nature of the disease in a young female is athognomonic of Takayasu’s arteritis. 35155c Courtesy of Laura Feldman MD. code CVS artery aorta arteritis inflammation Takayasu’s carotid thorax arch renal abdomen pulseless

 References