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Acute Aortic Disease.. - Index of

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200 Coady and Elefteriades<br />

for 6 cm aortas, the ultimate tensile strength <strong>of</strong> the aortic wall is easily exceeded.<br />

It is thus not at all surprising that rupture and dissection occur at these dimensions.<br />

The clinical data presented in this chapter, showing that bad clinical events occur<br />

at 6 cm, and this engineering data “dovetail” nicely. This engineering data helps<br />

to understand why the aorta ruptures at this critical dimension <strong>of</strong> 6 cm (Fig. G).<br />

We are in the process <strong>of</strong> measuring the same engineering data by transesophageal<br />

echocardiography (TEE), instead <strong>of</strong> epi-aortic echocardiography.<br />

This would take this method <strong>of</strong> investigation from a research tool to one <strong>of</strong> clinical<br />

utility. We look forward to reporting on this avenue further in the next one or two<br />

years. Measuring aortic wall stress, in addition to diameter, by this means may<br />

amplify our ability properly to time surgery so as to preclude the devastating complications<br />

<strong>of</strong> dissection and rupture.<br />

We are just beginning to investigate various biomarkers, such as the<br />

MMP serum levels and the RNA pr<strong>of</strong>ile <strong>of</strong> the blood as possible markers or aortic<br />

biology or predictors <strong>of</strong> aortic events. Further work needs to be done before<br />

clinical application (3).<br />

References<br />

1. Koullias G, Modak R, Tranquilli M, Korkolis DP, Barash P, Elefteriades J. Mechanical<br />

deterioration underlies malignant behavior <strong>of</strong> aneurysmal human ascending aorta.<br />

J Thorac Cardiovasc Surg 2005; 130:677–683.<br />

2. Vorp DA, Schiro BJ, Ehrlich MP, Juvonen TS, Ergin MA, Griffith BP. Effect <strong>of</strong><br />

aneurysm on the tensile strength and biomechanical behavior <strong>of</strong> the ascending aorta.<br />

Ann Thorac Surg 2003; 75:1210–1214.<br />

3. Wang Y, Elefteriades J, Iakobova O, et al. Gene Expression Pr<strong>of</strong>iling <strong>of</strong> Peripheral<br />

Blood for Diagnosis <strong>of</strong> <strong>Aortic</strong> Aneurysm. Cambridge Healthtech Institute’s Molecular<br />

Medicine Tri-Conference, San Francisco, CA, February 22, 2006.<br />

What medical management is appropriate for aneurysm patients under medical<br />

follow-up?<br />

One well-known study from Johns Hopkins University has driven the standard <strong>of</strong><br />

care in medical management <strong>of</strong> thoracic aortic aneurysm. In this study, a relatively<br />

small number <strong>of</strong> Marfans patients did better on beta-blocking medications than<br />

those treated without beta-blockers (1). Use <strong>of</strong> beta-blockers has, on the strength<br />

<strong>of</strong> this article, become standard <strong>of</strong> care. We believe that this issue needs to be<br />

revisited. These findings need to be replicated and extended to nonMarfan patients.<br />

In fact, the appropriateness <strong>of</strong> beta-blockade has been questioned, based on experimental<br />

studies suggesting that beta-blockers have deleterious mechanical effects<br />

on the aorta (2). Also, randomized studies <strong>of</strong> beta-blockers in abdominal aortic<br />

aneurysm have yielded equivocal results (3–4).<br />

Some very recent, very preliminary data suggests that angiotensin receptor<br />

blocking medications (ARBs) have a marked beneficial effect on growth <strong>of</strong> aortic aneurysms<br />

in a small animal model (5). This intriguing finding deserves further study.<br />

Benefit has been shown in an experimental model also for ACE inhibitiors (6).

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