Medical Image of the Week: Pulmonary Artery Dilation

Figure 1.  Axial section of the thoracic CT scan showing the massively dilated pulmonary trunk and artery.

The upper limit of the normal diameter of the main pulmonary artery on CT scan is 29 mm and of the right interlobar artery is 17 mm (1). A dilated pulmonary artery can arise from a variety of disease states. Most commonly from one of the many causes of pulmonary hypertension including idiopathic, previously termed primary, pulmonary artery hypertension (PAH). Other less common causes of pulmonary arterial dilation include pulmonary valvular stenosis, atrial septal defect, and idiopathic dilatation of the pulmonary artery.

Our patient is 66-year-old man with exertional dyspnea who was found to have a dilated pulmonary artery on thoracic CT scan during his work up (Figure 1).  His case is suspected to be idiopathic dilatation (1). This is a rare disease with estimates around 0.6% of patients with known congenital heart disease. The estimates in the general population are unknown. There have been a few different diagnostic criteria proposed, but most contain the following:

1. Dilation of the pulmonary trunk 
2. Absence of abnormal intracardiac or extracardiac shunts
3. Absence of chronic heart or lung disease
4. Absence of arterial diseases such as syphilis, arteriosclerosis or arteritis
5. Normal pressures in the right ventricle and pulmonary artery

Patients are usually asymptomatic or with minimal symptoms of dyspnea such as our patient. Rarely, it can present dramatically from compression of nearby structures. This includes constriction of the trachea or major branches or sudden cardiac death from compression of the left main coronary artery.

Tiffany Ynosencio MD and Swathy Puthalapattu MD

Division of Pulmonary, Allergy, Critical Care and Sleep

Banner-University Medical Center and Southern Arizona VA Health Care System

Tucson, AZ USA

Reference

1. Malviya A, Jha PK, Kalita JP, Saikia MK, Mishra A. Idiopathic dilatation of pulmonary artery: A review. Indian Heart J. 2017 Jan-Feb;69(1):119-24. [CrossRef] [PubMed]

Cite as: Ynosencio T, Puthalapattu S. Medical image of the week: pulmonary artery dilation. Southwest J Pulm Crit Care. 2018;16(1):46-7. doi: https://doi.org/10.13175/swjpcc012-18 PDF 

Medical Image of the Week: Pulmonary Artery Sling

Figure 1. Computerized tomography (CT) of the chest showing the aberrant origin of the left pulmonary artery from the right pulmonary artery creating a pulmonary artery sling with mild tracheal narrowing (arrow).

Figure 2. Cardiac magnetic resonance imaging (MRI) confirming the presence of a pulmonary artery sling with aberrant origin of the left pulmonary artery from the right pulmonary artery.

A 42-year-old year woman with asthma was admitted to the hospital with an asthma exacerbation. The patient complained of dyspnea on exertion, two-pillow orthopnea and bipedal edema. An echocardiogram showed a severely dilated right ventricle (RV) with elevated right ventricular systolic pressure of 71 mmHg. The systolic left ventricular (LV) function was also reduced with an ejection fraction of 45%. Computerized tomography (CT) of the chest showed an aberrant origin of the left pulmonary artery (PA) creating a pulmonary artery sling with mild tracheal narrowing (Figure 1, arrow). Cardiac magnetic resonance imaging (MRI) confirmed the presence of a pulmonary artery sling with the aberrant origin of the left PA from the right PA (Figure 2). Cardiac catheterization showed a mean PA pressure of 46mmHg with LV end diastolic pressure of 12mm Hg. The patient was diagnosed with WHO Group I pulmonary hypertension and started on treatment with sildenafil with a stable outpatient course.

Pulmonary artery sling is an uncommon form of vascular ring. The anomaly is a result of formation of the left PA from the right sixth vascular arch (rather than the left), leading to the left PA arising from the posterior aspect of the right PA (1). Pulmonary artery slings may produce symptoms of airway compression and esophageal compression and usually presents in childhood (2). In asymptomatic cases, a PA sling may mimic a mediastinal mass on chest radiographs and CT and MRI may be used to establish the diagnosis (3).

Abhinav Agrawal MD¹, Stuart L Cohen MD², Rakesh Shah MD², Arunabh Talwar MD FCCP¹

¹Division of Pulmonary, Critical Care & Sleep Medicine, Department of Medicine

²Division of Thoracic Radiology, Department of Radiology

Hofstra-Northwell School of Medicine

New Hyde Park, NY USA

References

1. Casta-er E, Gallardo X, Rimola J, Pallardó Y, Mata JM, Perendreu J, Martin C, Gil D. Congenital and acquired pulmonary artery anomalies in the adult: radiologic overview. Radiographics. 2006 Mar-Apr;26(2):349-71. [CrossRef] [PubMed]
2. Odell DD, Gangadharan SP, Majid A. Pulmonary artery sling: a rare cause of tracheomalacia in the adult. J Bronchology Interv Pulmonol. 2011 Jul;18(3):278-80. [CrossRef] [PubMed]
3. Ganesh V, Hoey ET, Gopalan D. Pulmonary artery sling: an unexpected finding on cardiac multidetector CT. Postgrad Med J. 2009 Mar;85(1001):128. [CrossRef] [PubMed] 

Cite as: Agrawal A, Cohen SL, Shah R, Talwar A. Medical image of the week: pulmonary artery sling. Southwest J Pulm Crit Care. 2017;15:160-61. doi: https://doi.org/10.13175/swjpcc116-17 PDF

Medical Image of the Week: Fibrosing Mediastinitis

Figure 1. Panel A: Thoracic CT showing airway occlusion (arrowhead) from fibrosing mediastinitis. Panel B: pulmonary artery obstruction (arrow) from fibrosing mediastinitis.

Histoplasmosis is endemic to the Midwest US and commonly causes an acute infection that presents as a subacute pneumonia. Chronic sequelae of histoplasmosis range from asymptomatic nodules to debilitating fibrosing mediastinitis (1). Mediastinal fibrosis represents exuberant scarring in response to histoplasmosis infection. Fibrosis may occlude airways (Figure 1A, arrow head) obstruct pulmonary arteries (figure 1B, arrow) or veins and impinge upon the esophagus and other vital structures residing in the mediastinum. Chest imaging shows subcarinal or mediastinal widening. CT scans may reveal fibrotic encasing of mediastinal structures and calcification of regional lymph nodes. Recurrent and often serious hemoptysis results from lung or airway damage and vascular compromise. Respiratory failure can occur. Treatment rarely includes stenting of airways or surgery (2). Vascular stenting may be indicated in some cases. Regardless, these difficult cases must be referred to centers with experience in histoplasmosis related complications.

¹Kenneth S. Knox, MD and ²Veronica A. Arteaga, MD

¹University of Arizona College of Medicine- Phoenix

²University of Arizona College of Medicine- Tucson

References

1. Peikert T, Colby TV, Midthun DE, Pairolero PC, Edell ES, Schroeder DR, Specks U.Fibrosing mediastinitis: clinical presentation, therapeutic outcomes, and adaptive immune response. Medicine (Baltimore). 2011 Nov;90(6):412-23. [CrossRef] [PubMed]
2. Hammoud ZT, Rose AS, Hage CA, Knox KS, Rieger K, Kesler KA. Surgical management of pulmonary and mediastinal sequelae of histoplasmosis: a challenging spectrum. Ann Thorac Surg. 2009 Aug;88(2):399-403. [CrossRef] [PubMed] 

Cite as: Knox KS, Arteaga VA. Medical image of the week: fibrosing mediastinitis. Southwest J Pulm Crit Care. 2017;14(2):85. doi: https://doi.org/10.13175/swjpcc015-17 PDF 

July 2014 Imaging Case of the Month

Michael B. Gotway, MD

Prasad M. Panse, MD

Department of Radiology

Mayo Clinic Arizona

Scottsdale, AZ

Clinical History: A 71-year-old Caucasian man presented for venous thromboembolism prophylaxis for a scheduled total right knee arthroplasty. His prior medical history was remarkable for anemia requiring transfusion of 4 units of blood 3 years prior to presentation, hypertension, prostatic hypertrophy, seasonal allergies, and glucose intolerance.

Frontal and lateral chest radiography (Figure 1) was performed.

Figure 1. Frontal (Panel A) and lateral (Panel B) chest radiography.

Which of the following statements regarding the chest radiograph is most accurate? (Click on the correct answer to proceed to the next panel)

1. The chest radiograph shows a circumscribed left lung mass
2. The chest radiograph shows a mediastinal mass
3. The chest radiograph shows bilateral symmetric linear and reticular opacities
4. The chest radiograph shows multifocal, bilateral consolidation
5. The chest radiograph shows numerous small nodules

Reference as: Gotway MB, Panse PM. July 2014 imaging case of the month. Southwest J Pulm Crit Care. 2014;9(1):15-24. doi: http://dx.doi.org/10.13175/swjpcc089-14 PDF