February 23 2008

Mal & Dave's

 Musings

Malcolm A Traill

IN  THE  PUBLIC  INTEREST
Updated 23/2/2008

 

  

DENGUE FEVER �

A TRIGGER FOR DISSECTION OF THE AORTA ?

 

 

Abstract

       Dissection of the aorta may start a week or two before catastrophic presentation

       An haemorrhagic diathesis in the context of controlled hypertension and shock may precipitate dissection

       Dengue fever may present in unusual ways

 

We report a catastrophic Aortic dissection occurring in a 52 year old travelling businessman with controlled hypertension, probably following Dengue fever.

After travelling through South East Asia on six back-to-back business trips, he returned to Melbourne, Australia feeling ill, then developing fevers, fatigue, chest pain cough and some facial petechiae over two weeks and two weeks before the dissection. He had travelled through Dengue�endemic areas (Vietnam, Singapore and China) and had contracted it earlier (at least twice) whilst in Asia.

The dissection was atypical in that it involved the lesser curve of the Aortic arch[1], then extended up into the right brachiocephalic artery, with two exit points in the
Aortic arch and descending aorta.

The Dengue serology was performed much later because Dengue is not endemic in Melbourne and its possibility was not entertained at the time; the past Dengue infections subsequently confirmed were for at least two, Dengue strains (I and II).

The dissection track had adherent thrombus and the adventitia had an acute inflammatory response (Figure1).

Figure 1

                                                             

FIGURE 1 - The dissection track is at the top, with the layered thrombus attached. The adventitia of the aorta, with sparse acute inflammatory cells (more conspicuous elsewhere), is at the bottom (with some processing separation). Dilated vasa vasorum venule and capillaries, with perivascular spilt red cells showing fragmentation, are in the media below the dissection track and thrombus.
[Masson trichrome, x 170 to a print measuring 15x10 cm].

 

 The vasa vasorum showed pericapillary oedema[2] and petechial haemorrhages (a �tourniquet test� equivalent) with red cell fragmentation.  
The picture was consistent with the dissection having commenced with petechial
and larger capillary leaks into the wall of the aorta at about the time of his worst
clinical symptoms (about two weeks prior to the clinical dissection). The histopathology of the aorta revealed cystic infarction of the media, with loss of nuclei (Figure 2).

Figure 2
      

FIGURE 2 - The Aortic intima is at the top right, the dissection track is below the bottom left. In the wall about midway between the two oxygen sources is a linear defect, consistent with infarction; having degeneration and cavitation, ghosting and loss of nuclei, probably well over one week old.      
[Masson trichrome, x 170 to a print measuring 15x10 cm].

Hypothesis: The pericapillary haemorrhages probably extended longitudinally in the wall by slow separation and oozing, with successive, additive breaches of vasa vasorum integrity, until the shear strains at the proximal end resulted in a breach of the intima and media and the full dissection.

A predisposition for such an �unzipping� process could have been the lowered compression forces between the layers of the aorta subsequent to hypertension treatment and any shock component associated with Dengue, creating a laxness which, in the context of viral endothelial damage and perivascular oedema, allowed vascular tears secondary to the systolic shearing forces.

 


Currently, we believe that dissection of the aorta is not a recognized potential complication of Dengue haemorrhagic fever because, in the past, Dengue infection and its complications have typically occurred in children and in areas of the world where treated hypertension is uncommon.

In the new age, Western, middle-aged, hypertensive travellers may be at increased risk for dissection of the aorta after travelling through Dengue endemic areas.

 

Malcolm A Traill

10 Munro Street

East Kew

Victoria 3102

AUSTRALIA

E-mail: matraill@iprimus.com.au

Telephone/Facsimile:61(3) 9859 8424

 

David Michaels

Hoppers Crossing

Victoria

AUSTRALIA

 

NOTE (added August 2011): Those interested in the role of the vasa vasorum vessels and artery disease may wish to read the review :

 Baikoussis NG, Apostolakis EE et al. Eur J Cardiothorac Surg. 2011;40(2):412-417

 

Acknowledgements: Nil

Competing interests: Nil

Funding: Selves

Copyright � MA Traill, February 2008-02-23, August 2011


 

[1] Roberts WC. Aortic dissection: anatomy, consequences and causes.

             Am Heart J. 1981; 101: 195-214

 

[2] Shresta S, Sharer KL, Prigozhin DM, et al. Murine model for Dengue virus

 induced lethal disease with increased vascular permeability. J. Virol. 2006; 80(20):10208-10217