Diagnosis and Assessment
Chest wall deformities
The chest wall is formed by the sternum, the ribs and the costal cartilages that join them. When these cartilages grow unevenly, the shape of the chest changes. This is common, and in most cases it occurs on its own without any associated disease.
There are three main patterns:
Pectus excavatum, or funnel chest, where the sternum is pushed inwards to create a central depression. It is the most common form, affecting around 1 in 400 people, and is about four times more frequent in men.
Pectus carinatum, or pigeon chest, where the sternum protrudes outwards. It is less common than excavatum and tends to become noticeable later in adolescence.
Pectus arcuatum, an uncommon mixed pattern in which the upper sternum protrudes with a depression below it. It does not behave like ordinary excavatum and is not always suited to the same operation, so it needs to be assessed on its own terms.
Investigations
CT thorax
Cardiopulmonary exercise testing
Pulmonary function tests
Provides cross-sectional imaging and allows measurement of the Haller index, calculated as the transverse diameter of the chest divided by the anteroposterior distance between the sternum and the vertebral column at the point of maximum depression.
Pulmonary function tests
Cardiopulmonary exercise testing
Pulmonary function tests
Measure lung volumes and airflow. In pectus excavatum, resting values are frequently within normal limits despite significant exertional symptoms, which is why exercise testing is often more informative.
Cardiopulmonary exercise testing
Cardiopulmonary exercise testing
Cardiopulmonary exercise testing
Measures ventilation, gas exchange and cardiac response during graded exercise. Limitation in pectus excavatum characteristically appears under load rather than at rest, and CPET frequently accounts for the discrepancy between normal resting investigations and exertional symptoms.
Echocardiography
Echocardiography
Cardiopulmonary exercise testing
Ultrasound assessment of cardiac structure and function. It demonstrates whether the sternum is compressing the heart, most commonly the right ventricle, and whether filling or function is affected.
Cardiac MRI
Echocardiography
Cardiac MRI
MRI gives unobstructed imaging and a direct, reliable measure of right ventricular function. Sequences can be timed to demonstrate whether compression varies through the respiratory cycle.