mTOR inhibition prevents angiotensin II-induced aortic rupture and pseudoaneurysm but promotes dissection in Apoe-deficient mice.

Aortic dissection and rupture are triggered by decreased vascular wall strength and/or increased mechanical loads. We investigated the role of mTOR signaling in aortopathy using a well-described model of angiotensin II-induced dissection, aneurysm, or rupture of the suprarenal abdominal aorta in Apoe-deficient mice. Although not widely appreciated, nonlethal hemorrhagic lesions present as pseudoaneurysms without significant dissection in this model. Angiotensin II-induced aortic tears result in free rupture, contained rupture with subadventitial hematoma (forming pseudoaneurysms), dilatation, or healing, while the media invariably thickens regardless of mural tears. Medial thickening results from smooth muscle cell hypertrophy and extracellular matrix accumulation, including matricellular proteins. Angiotensin II activates mTOR signaling in vascular wall cells, and inhibition of mTOR signaling by rapamycin prevents aortic rupture but promotes dissection. Decreased aortic rupture correlates with decreased inflammation and metalloproteinase expression, whereas extensive dissection correlates with induction of matricellular proteins that modulate adhesion of vascular cells. Thus, mTOR activation in vascular wall cells determines whether aortic tears progress to dissection or rupture. Previous mechanistic studies of aortic aneurysm and dissection by angiotensin II in Apoe-deficient mice should be reinterpreted as clinically relevant to pseudoaneurysms, and mTOR inhibition for aortic disease should be explored with caution.

Innominate artery injury from disseminated tuberculosis.

A 49-year-old man presented with chest pain and was found to have hemorrhage and drainage from a chest wound secondary to disseminated tuberculosis involving the sternum and ankle. He then developed acute hemorrhage from an innominate artery pseudoaneurysm originating just below a severely diseased sternoclavicular junction. A staged approach was used to manage his pathology given the life-threatening bleeding and his debilitated condition. He underwent endovascular stent grafting to exclude the pseudoaneurysm, followed by aggressive debridement of the affected sternal area.

An intriguing co-existence: atrial myxoma and cerebral cavernous malformations: case report and review of literature.

It is commonly postulated that neurologic complications of atrial myxomas are due to either direct tumor embolization or mycotic aneurysm of cerebral vasculature or rupture of mycotic aneurysms of cerebral arteries. However, the authors report the case of 63-year-old woman with a large left atrial myxoma whose progressive left-sided weakness was due to a different neurologic mechanism, namely, multiple bleeding cavernous malformations, which were visualized by magnetic resonance imaging of the brain. Cerebral cavernous malformations coexist with mesenchymal anomalies of other organs, including the liver, kidneys, and retinas. To the best of the authors' knowledge, this is only the second reported case of coexistent cerebral cavernous malformations and atrial myxoma.

Aortic arch replacement for recurrent cerebral embolization.

Replacement of the aortic arch for atheroma with cerebral embolization is in its infancy. The appropriateness of such intervention is controversial. Over a 10-month period, a 58-year-old woman suffered multiple debilitating cerebral vascular accidents manifested by motor, sensory, and memory deficits and documented by computed tomographic scanning and magnetic resonance imaging. Carotid and vertebral arteries were free of arteriosclerotic disease. Transesophageal echocardiography demonstrated two large atheromas with friable, pedunculated forms, one in the aortic arch and one in the very proximal descending thoracic aorta. Transcranial ultrasound revealed recurrent cerebral microembolic events. Cerebrovascular events continued, and the atheromas increased in size, despite treatment with Coumadin and aspirin. Under deep hypothermic arrest, the segment of the aortic arch harboring the atheroma was excised and replaced with a Dacron graft. Repeat transcranial ultrasound revealed cessation of embolic signals. All cerebrovascular events ceased. No further anticoagulation therapy was required. The patient has made substantial recovery from the preoperative deficits and continues to do well 1 year after aortic arch replacement. Resection of mobile aortic arch atheromas is likely to become increasingly important in the future as transesophageal echocardiography leads to their more common identification as a cause of cerebral ischemic events.