Cyanosis, Boots and the 5Ts

Labs and Lytes 023

Author: Chris Sia
Reviewers: Sarah Yong and Chris Nickson

A 60-year old gentleman presents with long standing dyspnea and cyanosis.

This is his chest x-ray:

Click on image to enlarge

Click on image to enlarge

Q1. Describe the x-ray findings?

This is an AP Erect chest x-ray. The most striking finding is the boot-shaped heart, in this case due to Tetralogy of Fallot.

Other features of this CXR:

  • Tracheal deviation to the left, pushed by mediastinal mass
  • Right lower zone alveolar opacity
  • Right internal jugular central line, tip appropriately within SVC
  • Right PICC
  • ECG leads

Q2. What are the differentials for an anterior mediastinal mass?

The 5Ts mnemonic is useful here:

  • Thymus: thymoma, thymic carcinoma
  • Thyroid: goitre, thyroid carcinoma, parathyroid neoplasms
  • Teratoma and other germ cell tumours
  • Thoracic aortic aneurysm (or other aortic abnormality!)
  • Terrible lymphoma: Hodgkin or non-Hodgkin


Q3. What is the likely cause of the mediastinal mass in this CXR?

Right sided aortic arch (this is seen in 25% of cases of TOF)

Q4. What are the 4 features of Tetralogy of Fallot?

Tetralogy of Fallot is a constellation of the following four cardiac abnormalities, arising from a single developmental defect:

  1. Ventricular septal defect
  2. Overriding aorta
  3. Right ventricular outflow tract obstruction
  4. Right ventricular hypertrophy

TOF accounts for 10% of congenital heart disease

References and links

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