Acute Hemothorax in Aortic Dissection Transcript
Acute Hemothorax in Aortic Dissection
This is Dr. Cal Shipley with the review of acute hemothorax due to aortic dissection with rupture of the aorta.
Rupture of the aorta is a potentially catastrophic complication of aortic dissection. Any rupture which occurs in the aorta outside the pericardium may lead to acute hemothorax.
For the purposes of this presentation, I’m going to assume that the aortic rupture occurs in the area of the aortic arch. During the process of aortic dissection, blood infiltrates between the layers of the aortic wall. Localized accumulations of blood may cause bulging and stretching of the aortic wall. This stretching may result in weakening of the wall structure and ultimately rupture.
When rupture occurs, blood is forced under high pressure into the left chest cavity, also known as the left hemithorax. The blood hemorrhaging from the rupture fills the space between the left lung and the chest wall surrounding it. This is hemothorax. As hemorrhaging continues, pressure within the hemothorax increases, forcing the left lung to collapse.
Once the lung has collapsed, there is no further space within the hemithorax for the blood to occupy. As a result, pressure is exerted against the soft tissue structures of the mediastinum, namely the heart contained within the pericardial sac, and the great vessels, the aorta and the vena cava and their branches. This phenomenon is known as a mediastinal shift and may be viewed on plain film chest X-ray.
Circulatory and Oxygenation Impairment
Needless to say, the collapse of the left lung, which effectively reduces the ability to oxygenate by 50% in an individual who has already lost a large volume of blood into the hemothorax, and particularly in combination with pressure on the heart and great vessels, which can cause further circulatory impairment, and may lead to devastating consequences including shock, and even death, if not rapidly corrected.
Let me also add that other causes of aortic rupture such as aortic aneurysm may lead to acute hemothorax by the same mechanism.
If you haven’t already done so, you can learn a lot more about aortic dissection by looking at my article in the Ship’s log.
You can also put the term aortic dissection into the search box on the homepage to get a complete listing of related video presentations on the site.
Cal Shipley, M.D. copyright 2020