Guilt by association: paradigm for detecting a silent killer (thoracic aortic aneurysm)

Abstract

Recent studies have confirmed a close association between various medical conditions (intracranial aneurysm, abdominal aortic aneurysm, temporal arteritis, autoimmune disorder, renal cysts), certain aortic anatomic variants (bovine aortic arch, direct origin of left vertebral artery from aortic arch, bicuspid aortic valve), and family history of aneurysm disease with thoracic aortic aneurysm and dissection. This paper reviews these associations. We propose to capitalise on these associations as powerful and expanding opportunities to diagnose the virulent but silent disease of thoracic aortic aneurysm. This can be accomplished by recognition of this 'guilt by association' with the other conditions. Thus, patients with associated diseases and anatomic variants should be investigated for silent aortic aneurysms. Such a paradigm holds substantial potential for reducing death from the silent killer represented by thoracic aortic aneurysm disease.

Figure 1

An ascending aorta so thin that the writing on a ruler can be read directly through the wall. It is sobering to think that this was all the tissue restraining the bloodstream and blood pressure in this patient. It is presumed that MMPs participated in the underlying destruction of the aortic wall that resulted in such loss of substance. MMP, matrix metalloproteinases.

Figure 2

A large thoracoabdominal aneurysm is being resected. The patient's head is to the left and his feet are to the right. The diaphragm has been divided. Note the ‘python-like’ enlargement of this aorta. A sterile soda can (6.2 cm) denotes the attainment of a dangerous aortic diameter. If the patient's aorta is approaching the size of a soda can, it must be resected.

Figure 3

Schematic representation of the four ways in which acute aortic dissection can take a patient's life: (1) intrapericardial rupture, leading to cardiac tamponade; (2) free rupture, usually into the left pleural space; (3) acute aortic insufficiency, which is usually very poorly tolerated, even leading to shock; (4) occlusion of virtually any branch of the aorta, from the coronary arteries to the iliacs. Because any branch of the aorta can be occluded by the dissection process, aortic dissection can mimic disease of any organ of the body, earning its well-deserved reputation as ‘the great masquerader’. Reproduced with permission from Elefteriades et al.

Figure 4

Pharmacological anti-impulse therapy. Diagram of aortic pressure curves under various conditions. The continuous line (B) represents the baseline state. Administration of a vasodilator agent such as nitroprusside is represented by the dashed curve (A). There is significant decrease in pressure levels and acceleration in heart rate, but this is accompanied by a steepest slope of the ascending portion of the curve (increased dp/dtmax). β-Blockade administration is represented by the dotted line (C). Although the degree of pressure lowering is usually smaller, the drug's negative inotropic and chronotropic effects result in decreased impulse and dp/dtmax. Reproduced with permission from Sanz et al.

Figure 5

The thumb-palm sign. Note the extension of the thumb beyond the border of the flat palm, indicating excessive long bones and lax joints. This indicates connective tissue disease and should prompt an aneurysm investigation.

Figure 6

Paradigm of “Guilt by Association” for detection of silent thoracic aortic aneurysms.