A type B aortic dissection is a tear in the inner wall of the aorta, your body’s largest blood vessel, that occurs in the descending portion of the aorta, past where the artery branches off to supply your left arm. Blood forces its way through the tear and creates a second channel, called a “false lumen,” between the layers of the vessel wall. This is a serious, potentially life-threatening condition, though it is generally less immediately dangerous than a type A dissection, which involves the section of the aorta closest to the heart.
Where the Tear Happens
The aorta arches up from the heart, curves overhead, then descends through the chest and into the abdomen, branching along the way to supply blood to nearly every organ. In the Stanford classification system, which is the one most commonly used, a type B dissection is defined as one that starts in the descending aorta, below the takeoff of the left subclavian artery. It can extend further down into the abdominal aorta, but it does not involve the ascending portion near the heart.
This distinction matters because the ascending aorta sits right next to the heart and the blood vessels feeding the brain. Tears there (type A) carry a much higher risk of immediately fatal complications like cardiac tamponade or stroke, and they almost always require emergency open-heart surgery. Type B dissections, while still dangerous, often allow for a different treatment approach.
What It Feels Like
The hallmark symptom is sudden, severe pain, often described as tearing or ripping. For type B dissections specifically, the pain typically centers in the upper back between the shoulder blades, though it can also radiate to the chest or abdomen. Some people experience sudden severe stomach pain, particularly when the dissection extends into the abdominal aorta. The pain may migrate as the tear propagates further along the vessel wall.
Because these symptoms overlap with heart attacks, pulmonary embolism, and other emergencies, imaging is essential for diagnosis. CT angiography is the standard first-line test in emergency departments. A meta-analysis of studies evaluating CT angiography for dissection found pooled sensitivity of 100% and specificity of 98%, making it extremely reliable. MRI offers similar accuracy (sensitivity of 92% to 98%, specificity of 100%) but takes longer and is less practical in an acute setting.
Uncomplicated vs. Complicated Dissection
Once diagnosed, a type B dissection is classified as either uncomplicated or complicated, and this distinction drives the entire treatment plan.
An uncomplicated dissection means the tear is stable: blood is flowing normally to your organs, the aorta isn’t rupturing, and your pain is controllable. Most type B dissections fall into this category. A complicated dissection means something has gone wrong beyond the tear itself. The most dangerous complications are rupture (or signs the aorta is about to rupture) and malperfusion syndrome, where the expanding false channel compresses or blocks blood flow to vital organs.
Malperfusion can affect the kidneys, intestines, liver, spinal cord, or legs. One of the tricky aspects of mesenteric (intestinal) malperfusion is that abdominal pain is absent in more than 40% of patients who have it, while roughly 20% of patients without malperfusion do experience abdominal pain. This makes lab work and imaging critical rather than relying on symptoms alone. Left unchecked, malperfusion triggers an inflammatory cascade that can cause irreversible organ damage.
How Uncomplicated Cases Are Treated
For uncomplicated type B dissections, the 2022 ACC/AHA guidelines are clear: medical management is the first-line therapy. The immediate priority is reducing the force of blood pushing against the damaged aortic wall, which means lowering both blood pressure and heart rate aggressively.
Treatment targets a systolic blood pressure of 100 to 120 mmHg and a heart rate under 60 beats per minute. This is typically achieved with intravenous medications in an intensive care setting during the acute phase, then transitioned to oral blood pressure medications for the long term. Pain control is equally important, not just for comfort but because pain itself drives up blood pressure and heart rate.
Many patients with uncomplicated dissections do well with this approach. Data from the International Registry of Acute Aortic Dissection showed a 1-year survival rate of roughly 90% for patients discharged on medical therapy, with 3-year survival around 78%. These numbers are comparable to survival rates seen with surgical or endovascular treatment in uncomplicated cases.
When Intervention Is Needed
Complicated dissections are a different situation entirely. When the aorta is rupturing or organs are losing blood supply, a procedure called TEVAR (thoracic endovascular aortic repair) is considered life-saving. This involves threading a stent graft through a blood vessel in the groin and deploying it inside the aorta to seal off the tear and restore normal blood flow. It is far less invasive than open surgery and has become the preferred approach for most complicated type B dissections.
Even in patients who start with uncomplicated dissections, some will develop problems over time. The weakened aortic wall can gradually expand into an aneurysm. Current guidelines recommend considering repair when the descending aorta reaches 5.5 cm in diameter, since diameters above 6 cm are associated with significantly higher rates of rupture and death. Repair may be recommended at smaller sizes for people with connective tissue disorders like Marfan syndrome or Loeys-Dietz syndrome, those with rapid aortic growth (0.5 cm or more per year), women (who face higher rupture risk at smaller diameters), or people with a family history of dissection or aortic aneurysm.
Long-Term Monitoring
A type B dissection is not a one-time event you recover from and move on. The dissected aorta remains structurally vulnerable for the rest of your life, and regular imaging surveillance is essential to catch aneurysmal expansion or new complications early.
For patients managed with medication alone, an early follow-up scan around 3 months is particularly valuable. During this subacute phase, important changes in the aorta’s shape and size often emerge, and catching them early keeps treatment options open. After that initial period, imaging is typically performed at 6 months, 12 months, and annually thereafter. If the aorta remains stable over several years, follow-up intervals may stretch to every 1.5 to 3 years. If growth or new problems are detected at any point, scans become more frequent.
Patients who undergo TEVAR follow a similar schedule: imaging at around 1 month, 6 months, and 12 months post-procedure, then annually going forward. Even when the repair looks good and the aorta stabilizes, continued annual imaging is recommended indefinitely.
Beyond imaging, lifelong blood pressure control is the single most important thing you can do. Uncontrolled hypertension remains the primary driver of late complications, including aneurysm formation and re-dissection. Most patients will take blood pressure medications permanently and are advised to avoid heavy lifting and other activities that cause sudden spikes in blood pressure.