What Does Intramural Hematoma Mean?

September 30, 2025 •

3 min read

Intramural hematoma accounts for 10-30% of all acute aortic syndromes, a potentially life-threatening set of conditions involving the body's largest artery. So, what does intramural hematoma mean, and why is rapid diagnosis critical for patient outcomes?

Quick Summary

An intramural hematoma (IMH) is a serious vascular condition where bleeding occurs within the layers of the aortic wall, characterized by a lack of a primary tear in the innermost lining (intima) of the aorta.

Key Points

Aortic Bleeding: An intramural hematoma (IMH) is blood pooling within the middle layer of the aorta's wall, not in the main channel.
No Intimal Tear: Unlike a classic aortic dissection, IMH is defined by the absence of an initial tear or flap in the innermost layer of the aorta.
Sudden, Severe Pain: The most common symptom is an abrupt, intense pain in the chest or back, similar to an aortic dissection.
Imaging is Key: Diagnosis relies on advanced imaging techniques like CT or MRI, which reveal the thickened aortic wall and distinguish IMH from other conditions.
Type A vs. Type B: IMH is classified based on location. Type A (involving the ascending aorta) requires emergency surgery, while uncomplicated Type B (involving the descending aorta) is often managed medically.
Risk of Progression: An IMH can progress to a full aortic dissection or rupture, making close monitoring and rapid treatment crucial.

Understanding the Intramural Hematoma

To understand what intramural hematoma means, it's helpful to know about the aorta. The aorta is the body's main artery, responsible for carrying oxygenated blood from the heart. Its wall has three layers: the intima (inner), media (middle), and adventitia (outer).

An intramural hematoma (IMH) is characterized by bleeding within the medial layer of the aortic wall without a tear in the intima. It's a type of acute aortic syndrome, a group of serious conditions affecting the aorta. While once considered a variation of aortic dissection, IMH is now recognized as a distinct issue.

How does an intramural hematoma form?

The exact cause isn't always clear, but several theories exist:

Rupture of small vessels: The most accepted idea is that tiny blood vessels supplying the aortic wall, called vasa vasorum, rupture and cause bleeding within the media.
Microscopic tears: Another possibility is that small, unseen tears in the intima allow blood to enter the wall.
Penetrating ulcer: An ulcer in the aortic lining can deepen and lead to a localized hematoma.

An IMH weakens the aorta and can either heal on its own, progress to a classic dissection, or lead to a dangerous rupture.

Symptoms and Diagnosis

Diagnosing IMH can be challenging as its symptoms often resemble other heart emergencies.

Common symptoms of intramural hematoma

The most common symptom is sudden, severe pain:

Chest pain: Often described as tearing or searing.
Back pain: Pain radiating between the shoulder blades.
Abdominal pain: Less common but can occur.
Shortness of breath
Fainting or dizziness
Signs of complications: These can include paleness, sweating, anxiety, or a weak, rapid pulse.

Diagnostic tools

Imaging is crucial to identify an IMH and differentiate it from other aortic problems.

CT scan: Frequently used in emergencies, a CT scan can show a thickened aortic wall. With contrast, it helps confirm the absence of an intimal flap.
MRI: Provides detailed images and can distinguish IMH from a clotted false lumen in a dissection.
TEE: Offers clear views of the ascending aorta and arch, helping to identify wall thickening.
Blood tests: While not definitive for diagnosis, they can help rule out other conditions.

Classification and Treatment

IMH is typically classified using the Stanford system, which guides treatment.

Stanford classification

Type A IMH: Affects the ascending aorta. This is an emergency requiring surgery due to high mortality risk.
Type B IMH: Located in the descending aorta, usually managed more conservatively.

Comparison of IMH vs. Aortic Dissection


Feature	Intramural Hematoma (IMH)	Classic Aortic Dissection (AD)
Initial Pathophysiology	Bleeding within the aortic wall's medial layer.	Tear in the intima, creating true and false lumens.
Intimal Flap	Absent.	Present.
Blood Flow	No continuous flow in the hematoma.	Flow in the false lumen.
Progression Risk	Can progress to dissection or rupture.	Risks include rupture and malperfusion.
Typical Patient Profile	Older, often with hypertension and atherosclerosis.	Wider age range, linked to conditions like Marfan syndrome.

Treatment options

Treatment varies depending on the type of IMH and if there are complications.

Medical management: Standard for uncomplicated Type B IMH, focusing on strict blood pressure and heart rate control with medications like beta-blockers and calcium channel blockers. Pain relief is also important. Regular imaging monitors the hematoma.
Surgical repair: Required for all Type A IMHs due to the high risk of rupture. This involves replacing the affected section of the aorta with a graft. Surgery is also needed for complicated Type B IMHs.
TEVAR: A less invasive option for Type B IMH, especially in complicated cases. A stent-graft reinforces the aortic wall.

Conclusion

An intramural hematoma is a serious condition requiring immediate medical attention. Understanding what intramural hematoma means, its causes, symptoms, and treatment is vital for prompt and accurate diagnosis. While uncomplicated Type B IMH can often be managed medically, Type A cases necessitate urgent surgery due to the high risk. Advances in imaging and endovascular techniques continue to improve outcomes for patients with this complex aortic issue. For more information, the American Heart Association offers valuable resources on aortic diseases.

American Heart Association - Aortic Intramural Hematoma

Frequently Asked Questions

The main difference is the presence of an intimal tear. In an intramural hematoma, blood collects within the aortic wall without a tear in the innermost lining (intima). In a classic aortic dissection, there is a tear that allows blood to flow into and separate the layers of the wall, creating a true and a false lumen.

The primary symptoms include the sudden, acute onset of severe chest or back pain, which can feel tearing or searing. Other symptoms may include shortness of breath, fainting, a rapid pulse, or severe abdominal pain.

Yes, an intramural hematoma is a potentially life-threatening condition and is considered a form of acute aortic syndrome. If it progresses to a full aortic dissection or aortic rupture, it can be fatal.

Diagnosis is primarily made using imaging techniques. A computed tomography (CT) scan is the most common tool, revealing a thickened aortic wall. Magnetic Resonance Imaging (MRI) and Transesophageal Echocardiography (TEE) are also used to confirm the diagnosis.

Risk factors include chronic high blood pressure, connective tissue disorders like Marfan syndrome, severe atherosclerosis, blunt chest trauma, and conditions that weaken the aortic wall.

Treatment depends on the location. Type A IMH (involving the ascending aorta) requires immediate surgical repair. Uncomplicated Type B IMH (involving the descending aorta) is typically managed with medication to control blood pressure and heart rate.

Yes. For many patients, especially those with uncomplicated Type B IMH treated medically, the hematoma can be reabsorbed and the patient can make a full recovery. However, careful follow-up with regular imaging is required to monitor for potential complications.