A cardiac bronchus is a rare variant of normal bronchial anatomy, arising from the medial aspect of the bronchus intermedius.
This anomaly is rare and is reported in around 0.09 to 0.5% of individuals 3-5. There may be a predilection for males. It is the only recognised true supernumerary bronchus, with other anomalies representing aplasia or abnormal branching patterns 3.
The vast majority of cardiac bronchi are asymptomatic. In some patients with lung parenchyma supplied by this bronchus, abnormal drainage predisposes to repeated chest infection 2. Haemoptysis has also been described 4.
The anomaly is thought to occur between the 4th and 6th weeks of gestation, during development of the bronchial tree 3.
The histology of its wall is that of normal airway.
A cardiac bronchus arises from the bronchus intermedius, opposite and just distal to the origin of the right upper lobe bronchus. It is variable is size, morphology and length (range from 5mm to 5cm)1,3. In about half of cases the cardiac bronchus is a short blind ending bronchial stump with no branches and does not supply any lung parenchyma. In the remainder, the bronchus may have branches and a an amount of aerated lung parenchyma 1.
A cardiac bronchus is almost always an incidental finding of CT examination of the chest. It appears as a continuation of the the lumen of the right main bronchus, projecting medially and directly inferiorly towards the posterior aspect of the heart.
In some cases the dependent lung parenchyma may be collapsed and mimic a soft tissue mass 2.
Treatment and prognosis
As these structures are usually asymptomatic no treatment is required. In rare instances where recurrent infections can be attributed to a cardiac bronchus then surgical resection may be carried out 3.
There is usually little if any differential diagnosis as most cases are classical in appearance. In atypical cases, differential includes:
- different histologically : diverticula do not have normal bronchial wall morphology
- necrotic / cavitating mass
- a consideration when associated lung parenchyma is atelectatic
- 1. Shields TW. General Thoracic Surgery. Lippincott Williams & Wilkins. (2009) ISBN:0781779820. Read it at Google Books - Find it at Amazon
- 2. Parker MS, Christenson ML, Abbott GF. Teaching atlas of chest imaging. (2006) ISBN:3131390212. Read it at Google Books - Find it at Amazon
- 3. Mcguinness G, Naidich DP, Garay SM et-al. Accessory cardiac bronchus: CT features and clinical significance. Radiology. 1993;189 (2): 563-6. Radiology (abstract) - Pubmed citation
- 4. Keane MP, Meaney JF, Kazerooni EA et-al. Accessory cardiac bronchus presenting with haemoptysis. Thorax. 1997;52 (5): 490-1. Thorax (link) - Free text at pubmed - Pubmed citation
- 5. Müller NL, Silva CI. Imaging of the chest. (2008) ISBN:141604048X. Read it at Google Books - Find it at Amazon
Synonyms & Alternative Spellings
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