Tuesday 28 May 2013
Cardiovascular syphilitic infection
The incidence of late manifestations of syphilis have declined almost to a rare entity since the era of antibiotics. Before the discovery of penicillin, tertiary syphilis infection was the most common cause of thoracic aortic aneurysm, resulting in 5–10% of cardiovascular deaths.
The primary lesion of cardiovascular syphilis is aortitis, an inflammatory response to the invasion of the aortic wall by the Treponema pallidum that evolves to obliterative endarteritis of the vasa vasorum and results in necrosis of the elastic fibres and connective tissue in the aortic media.
The resulting weakening of the aortic wall will progress into the late vascular manifestations of syphilis.
Syphilitic aortitis is reported in 70–80% of untreated cases after the primary infection, and in 10% of these patients, significant cardiovascular complications will occur, such as aortic aneurysm, aortic regurgitation and coronary ostia stenosis.
The ascending aorta is the segment most commonly affected (50%), followed by the arch (35%) and the descending aorta (15%) . The rich lymphatic arrangement in the ascending aorta that may predispose greater mesoaortitis is believed to be the cause for larger involvement of this segment.
Cardiovascular syphilis is a late form of syphilis, which usually manifests in the 4th–5th decade of life, typically 5–40 years after the primary infection. It may become symptomatic with thoracic pain or symptoms of compression of the surrounding structures, but can enlarge asymptomatically until incidental finding in a chest X-ray or a catastrophic and often fatal aneurysmal rupture.
Without surgical treatment, the mortality rate at 1 year can reach 80% due to the high rate of rupture of these aneurysms.
Cardiovascular syphilitic infection has nearly disappeared in developed countries, although it remains a differential diagnosis in developing nations. Recent epidemiologic reports show an increase in reported cases related to the HIV infection.
The rarity of this aetiology makes the diagnosis difficult, mainly because syphilis testing is not routinely used. In late syphilis, non-treponemal tests like VDRL test and rapid plasma reagin test are less sensitive (71–73%), when compared with treponema-specific tests such as TPHA, micro-haemagglutination test, flourescent treponemal antibody absorption test (94–96%).
According to Kuramochi et al. , serologic proved syphilis is necessary to make the diagnosis of syphilitic aortitis, the histologic findings of mesoaortitis by itself is not diagnostic.
In the presence of an aortic aneurysm, particularly in younger patients, syphilitic serological testing is advised.
CT angiogram is the best imaging study to define the size and anatomy of the aneurysm, but in the setting of an aneurysm, the echocardiogram and coronary angiogram are mandatory to exclude aortic regurgitation and coronary flow-limiting lesions.
The definitive treatment of aortic aneurysm is surgical repair, which involves resection of the dilated portion of the aorta and replacing it with a synthetic vascular graft.
The simultaneous presence of aortic regurgitation or significant coronary disease should be surgically treated at the same time.
Surgery and specific antibiotic treatment does not exclude future manifestations of the disease, even after erradication of the Treponema pallidum, which makes permanent follow-up needed.