An ascending aortic aneurysm is a dangerous ballooning or weakening of the upper section of the aorta, the body’s largest artery that carries oxygenated blood directly from the heart. This condition can progress silently, but its primary risk lies in the potential for rupture or dissection, which involves a tear in the artery’s inner lining. Because of the catastrophic nature of these events, surgical repair is often the definitive and life-saving treatment once the aorta reaches a certain size or begins to grow rapidly.
Criteria for Determining the Need for Repair
The decision to move from “watchful waiting” to surgical intervention is based on a careful assessment of the maximum diameter of the aneurysm, where the risk of rupture or dissection begins to outweigh the risk of the operation itself. For most asymptomatic patients, surgical repair is recommended when the ascending aorta reaches a diameter of 5.5 centimeters (cm).
This standard threshold is frequently lowered based on underlying patient conditions or the rate of enlargement. Individuals with certain genetic conditions, such as Marfan syndrome, often have weaker aortic tissue and may require surgery at a smaller diameter (as low as 4.5 cm). Patients with Loeys-Dietz syndrome might have an even lower threshold, with repair considered at 4.0 cm.
A quick rate of growth is also a significant concern. Surgery is mandated if the aneurysm grows by 0.5 cm in a single year, or if sustained growth exceeds 0.3 cm per year over two consecutive years. Any patient presenting with symptoms suggestive of dissection, such as severe chest or back pain, requires immediate emergency surgery, irrespective of the aneurysm’s diameter. If a patient is already undergoing a different open-heart procedure, such as aortic valve replacement, the ascending aorta may be prophylactically replaced at a smaller size (often 4.5 cm) because the added risk is minimal.
Open Surgical Aortic Graft Replacement
The standard method for repairing an ascending aortic aneurysm that does not significantly involve the aortic valve is an open surgical aortic graft replacement. This major operation requires a median sternotomy, where the breastbone is divided to allow the surgeon access to the heart and aorta. The patient is then placed on cardiopulmonary bypass, a heart-lung machine that temporarily takes over the function of the heart and lungs, allowing the surgeon to work on a still, bloodless heart.
The surgeon removes the diseased, weakened section of the ascending aorta. This excised segment is then replaced with a synthetic tube graft, most often made of a durable, biocompatible material like Dacron.
The Dacron graft is sewn to the remaining healthy sections of the aorta both above and below the excised portion. This new tube serves as a conduit for blood flow, effectively eliminating the risk of rupture in the repaired section. Once the graft is secured and tested for leaks, the patient is weaned off the heart-lung machine, and the chest is closed.
Addressing Aortic Valve Involvement
In many cases, the aneurysm extends downward to involve the aortic root. When this occurs, the repair must address both the aneurysm and the integrity of the valve, leading to two primary surgical strategies. The first is a composite valve graft replacement, which involves replacing the diseased aortic root, the ascending aorta, and the aortic valve with a single unit.
This composite graft consists of a synthetic tube with a prosthetic valve—either mechanical or biological—already sewn inside it. After the complex is replaced, the openings for the coronary arteries are reattached to the side of the new Dacron graft. A mechanical valve requires the patient to take lifelong blood-thinning medication, while a biological valve has a limited lifespan (typically 10 to 15 years) but avoids the need for long-term anticoagulation.
The second approach, preferred in younger patients with a healthy valve, is a valve-sparing root replacement (VSRR). This procedure replaces the aortic root and ascending aorta with a graft but preserves the patient’s native aortic valve leaflets. The native valve is re-implanted inside the new Dacron tube, and the coronary arteries are reattached to the graft. VSRR is beneficial because it avoids the long-term complications and anticoagulation requirements associated with prosthetic valves.
Recovery and Long-Term Management
The immediate post-operative period begins in the Intensive Care Unit (ICU), where the patient’s vital signs are monitored. Patients receive support, including mechanical ventilation and drainage, until they can breathe independently. The total hospital stay typically ranges from four to ten days.
Pain management is a primary focus, and patients are given medications to control discomfort, which helps them begin early mobilization. Patients are encouraged to start walking short distances soon after surgery to prevent complications like blood clots and pneumonia. Full recovery from open-chest surgery is a gradual process, with strenuous activity and heavy lifting restricted for approximately three months.
Long-term management focuses on protecting the remaining aorta. Lifelong medication, particularly for strict blood pressure control, is required to reduce shear stress on the arteries. Regular follow-up imaging, such as CT or MRI scans, is necessary to monitor the graft and other sections of the aorta.