INTRODUCTION

Acute aortic syndromes (AAS) encompass a group of aortic wall conditions manifesting clinically with sudden onset and intense tearing chest and/or back pain with radiation to the lower abdomen and pelvis¹. The most common AAS is acute aortic dissection (AAD). AAD is a cardiovascular emergency associated with high rates of morbidity and mortality requiring prompt surgical management to sustain life¹.

AAD can be classified using the Stanford and DeBakey systems^2,3. Stanford type A aortic dissections involve the ascending aorta and originate anywhere from the aortic root to the origin of the brachiocephalic trunk. This dissection pattern has been associated with rapidly occurring and lethal complications². Aortic dissections developing anywhere throughout the length of the aorta except for the ascending aortic part are classified as Stanford type B². The DeBakey system typifies lesions according to the location of the initiating intimal tear and the pattern of extension¹. In DeBakey type I, the dissection originates in the ascending aorta and propagates distally to the descending aorta. In DeBakey type II, only the ascending aorta is involved while in DeBakey type III the dissection originates in the descending aorta and propagates distally^1,3.

From the acute onset of aortic wall injury, pathological responses and remodeling occurs which classifies aortic dissection as acute up to 2 weeks from onset, subacute from 2 weeks to 3 months, and chronic after 3 months^4,5.

Computed Tomography (CT) is pivotal in diagnosing, surveilling, and planning the appropriate intervention for aortic dissections⁶. Prognosis depends on many factors, which consist of preoperative, operative, postoperative, and patient specific factors. Pivotal predisposing risk factors include both acquired and genetic conditions that weaken the layers of the aortic wall. Vulnerable patients include those with; male sex, hypertension, atherosclerosis, previous cardiovascular surgery, an underlying aneurysm, connective tissue diseases such as Marfan syndrome, vascular type of Ehlers-Danlos syndrome, Loey’s-Dietz syndrome, congenital bicuspid aortic valve, inflammatory vasculitis such as giant cell arteritis and Takayasu arteritis.

DeBakey Type II dissection is a well-documented phenomenon affecting the ascending aorta either acutely or in a chronic manner. In this case report, though, a rare occurrence of DeBakey Type II dissection occurs due to a pre-existing chronic aortic aneurysm.

CASE REPORT

A 73-year-old man was admitted to a tertiary hospital in Athens, Greece for scheduled open surgical repair of an ascending aortic aneurysm. The patient presented with acute chest pain and the initial CT imaging on admission revealed an ascending aorta aneurysm with a diameter of 7.03 cm and an aortic root size of 3.9cm. Echocardiography showed moderate aortic and mitral valve insufficiency.

The patient’s past medical history was significant for surgical inguinal hernia repair, catheter ablation treatment for atrial fibrillation, and hypertension. Family history was insignificant. In addition, the patient reported daily alcohol intake but no tobacco or recreational drug use. Medication history was significant for olmesartan, medoxomil, and amlodipine for hypertension control, flecainide for rate control due to atrial fibrillation and apixaban for anti-coagulation. Lastly, clinical examination and laboratory tests were not significant for any irregular findings and coronary angiography did not reveal additional issues.

However, during the pre-operative CT angiography that was performed, an aortic dissection extending from the proximal ascending aorta to the brachiocephalic trunk (DeBakey Type II) was detected on the grounds of the pre-existing ascending aortic aneurysm. As of that, the patient management plan was altered and the final pre-operative diagnosis was documented as DeBakey Type II aortic dissection.

SURGICAL PROCEDURE

The operation was performed with the patient under general anesthesia in the supine position. A median sternotomy provided access to the thoracic cavity and cardiopulmonary bypass was established through cannulation of the left common femoral artery and the superior vena cava (SVC) and right atrium. Deep hypothermia (18°C) was employed to provide robust organ and cerebral protection during circulatory arrest, as the anatomical complexity of this case necessitated this approach to achieve enhanced cerebral protection since the repair duration might be prolonged due to technically difficult restoration.

Retrograde cardioplegia administration and retrograde cerebral perfusion (RCP) through the SVC were initiated to ensure adequate cerebral protection due to the dissection’s involvement of the brachiocephalic trunk. The decision to use SVC and atrial cannulation was made specifically to facilitate RCP.

As seen in the imaging, the dissection included the ascending aorta and the brachiocephalic trunk. Thus, the decision was made to proceed to a hemi-arch aortic replacement using a synthetic graft. For that purpose, a branched graft (Intergard Woven, 34mm, Medtronic Inc. Sacramento, CA) was selected, and replacement of the proximal arch and the dissected segment of the innominate artery was initially achieved. Following that, the graft was anastomosed with the proximal aorta and further reinforcement and hemostasis was achieved through felt placement. Lastly, the cross-clamp was released.

Gradual rewarming of the patient was achieved with concurrent physiological return of cardiovascular circulation. Lastly, a biventricular pacemaker and two chest tubes allowing pleural drainage were implanted, and the patient was weaned off cardiopulmonary bypass. Deep hypothermic circulatory arrest and retrograde cerebral perfusion time was approximately 30 minutes.

POSTOPERATIVE COURSE

The patient was transferred to the ICU following the end of the operation. In the first post-operative day the patient was extubated successfully, and oxygen saturation remained within the normal limits. The only significant abnormality was metabolic alkalosis due to base excess during the first post-operative day with a pH value of 7.409 and HCO₃^– concentration of 27.4 mmol/L but it was corrected with the administration of spironolactone soon after.

During the second post-operative day, the patient was transferred to the regular surgical floor and was later discharged on post-operative day six with significantly improved clinical presentation. Discharge medication included aspirin of 100mg twice daily, omeprazole 20mg twice daily, bisoprolol fumarate 2,5mg once daily, and paracetamol 1g as needed. He was scheduled for an early follow-up visit 10 days after discharge.

DISCUSSION

This case highlights a rare presentation of an acute DeBakey Type II aortic dissection occurring on a pre-existing chronic ascending aortic aneurysm. The unique properties of the ascending aorta’s mobility, combined with hemodynamic forces, play a significant role in the predisposition to acute aortic syndromes (AAS) in this anatomical region. The transition from the mobile segments of the ascending aorta to the immobile descending aorta at the isthmus is particularly vulnerable to deceleration injuries and spontaneous dissections, further potentiating the incidence of complications such as aortic dissection in the ascending aorta¹.

Diagnostic imaging, particularly computed tomography (CT), is essential in identifying the type, location, and extent of aortic dissections⁶. In this case, CT angiography was instrumental in detecting the dissection, confirming the involvement of the ascending aorta and brachiocephalic trunk, and guiding the decision for surgical intervention.

Aortic dissection associated with chronic aneurysms presents additional challenges. Literature suggests that 5% to 20% of aortic dissections are linked to arteriosclerotic aneurysms, with this incidence rising due to the aging population⁷. In particular, the overlap of an aortic aneurysm and dissection increases the risk of rupture if not addressed, underscoring the importance of timely surgical management⁷. In this case, the surgical approach of hemi-arch replacement, using a synthetic graft, effectively treated both the aneurysm and dissection, demonstrating a successful outcome despite the complexities of the condition.

This report also underscores the scarcity of documented cases of DeBakey Type II aortic dissection occurring on a pre-existing aneurysm, highlighting the need for further research. While there is ample literature comparing DeBakey Type I and II dissections, few studies focus on the intersection of chronic aneurysms and acute dissections. This case adds to the limited data, suggesting that the presence of an aneurysm may complicate both the clinical presentation and surgical management, necessitating individualized treatment plans based on the patient’s comorbidities, dissection pattern, and overall prognosis.

CONCLUSION

This case illustrates the critical importance of considering acute aortic dissection in patients with known aneurysms, even in the absence of classic risk factors such as trauma. Prompt diagnosis and intervention, guided by comprehensive imaging and individualized surgical planning, are essential for successful outcomes. Further research is warranted to explore the optimal management of acute aortic dissection in the context of chronic aneurysms, with the goal of improving both short- and long-term patient outcomes.