Infective endocarditis in intravenous drug users most commonly affects the tricuspide valve. More than 90% of cases of infective endocarditis in intravenous drug users are caused by staphylococcus or streptococcus species. When drug treatment and surgery is applied, intravenous drug users with infective endocarditis have an in-hospital survival rate of 91%.1
Pulmonary artery aneurysms often are associated with infective endocarditis or pneumonia and reveal a high mortality.2 3
Mycotic aneurysms and pseudoaneurysms of the pulmonary artery are a rare but severe complication especially in intravenous drug users with infective endocarditis of the right heart. Mortality from mycotic pulmonary artery aneurysms is high and has been estimated over 50%.4
Pathophysiologically, the dilatation of the vessel wall causes the aneurysm. In contrast, a pseudoaneurysm results from the destruction of the two inner layers of the vessel or sometimes even the destruction of the entire vessel wall. Haemorrhage is often prevented from fatal bleeding because of the surrounding thrombus, but there is a high risk of rupture of the aneurysms after complete destruction of the vessel wall, especially when the surrounding thrombus lyses. Therefore, aneurysms and pseudoaneurysms have a high risk of rupture with fatal bleeding.
Pulmonary artery aneurysms can also result from congenital causes like deficiency of the vessel wall, valvular and postvalvular stenosis, increased flow due to left to right shunt, pulmonary arterial hypertension with chronic pulmonary embolisms, septic microemboli to the vasa vasorum, an infective focus, an iatrogenic catheter trauma and inflammatory erosion secondary to infections such as haematogenous seeding, vasculitis or trauma with direct contamination.5
In cases of aneurysms caused by septic embolism, S aureus
is often detected in blood cultures.4 6
However, other microorganisms, including Mycobacterium tuberculosis
and Treponema pallidum
can cause these aneurysms. Mycotic pulmonary aneurysms have been described in conjunction with endocarditis in injecting drug users.4
Early diagnosis and subsequent surgical or interventional treatment is the main goal as there is a high risk of rupture.2 4
Our patient was admitted to hospital with haemoptysis and lobectomy was performed immediately. Lobectomy or, in rare cases, pneumonectomy is the standard treatment option even if it is associated with high perioperative morbidity.7
However, the optimum management of a case like that is not defined in current international guidelines. Few cases have been described that were managed conservatively.8
Alternative treatment options include transcatheter embolisation with detachable balloons, coils, stent grafts and vascular plugs, which are less invasive than the surgical treatment.9
However, coil embolisation can only be performed if the aneurysm can be technically reached by catheterisation.7 10 11 12
In this case, life-threatening haemoptysis occurred presumably due to rupture of the pseudoaneurysm. Due to the location of the aneurysm in the right lower lobe surgical intervention involved lobectomy as standard procedure. As the patient was in a good clinical condition, surgery was performed immediately. To avoid pulmonary amputation, aneurysmectomy or occlusion of the arterial defect by direct suture can be applied.
However, these techniques are associated with a high mortality. Massive haemoptysis was observed after suture line rupture and the penetration to the adjacent bronchi.
In our case, lobectomy and pulmonary artery plasty was performed for complete resection of the damaged pulmonary artery wall. This procedure was safe and simple and was the definitive treatment for pulmonary artery aneurysm.13
Reconstruction or replacement of the tricuspid valve with severe regurgitation was not performed mainly because a sternotomy would not have allowed control of the bleeding in the right lung quickly. Performing both, the tricuspid intervention and the lobectomy would have caused a highly elevated morbidity and mortality risk regarding septic complications and perioperative bleeding during extracorporal circulation. Following the strategy of surgical treatment of the ruptured mycotic aneurysm and the conservative management of the tricuspid endocarditis, the perioperative risk for the patient was reduced significantly. Follow-up examinations showed a good clinical outcome and, up to now, tricupide valve reconstruction or replacement was not necessary.
It is important to recognise the development of mycotic aneurysms in intravenous drug users who present with infective endocarditis and sudden haemoptysis or who have a history of infective endocarditis and suspicious findings in the CT or radiograph. This typical complication can be life threatening, but various therapeutic options exist when detection is early. Individual treatment plans must be developed.
- Infective endocarditis of the right heart can cause septic embolism with severe pulmonary complications.
- Mycotic aneurysms are associated with infective endocarditis and high mortality as their rupture can lead to fatal haemorrhage.
- Early diagnosis and immediate treatment significantly reduces the morality rate.
- Treatment must be planned individually, including interventional treatment and surgery.
- Reconstruction or replacement of the involved valve is not mandatory.