Q1: Describe the characteristic pathologic features of heart and lungs in congestive heart failure. 

• Heart is enlarged
• Changes in cardiac chambers and myocardium depend on the etiology of heart failure.
• Irregular fibrosis replaces myocardium.  
• Lung shows severe, chronic passive congestion.  
• Vessels, including alveolar capillaries, are congested as a result of pulmonary venous hypertension.
• Alveoli contain numerous hemosiderin laden macrophages. 

Q2: Anticipated findings in Chest x-ray in a patient with congestive heart failure.

Following images exemplify the findings of congestive heart failure in CXR.

Cardiomegaly: 

• Cardiac width is larger than half trans-thoracic diameter.  Cardiothoraccic rartio >0.5.
• You can encounter normal size heart in acute myocardial infarction or in volume overload.

Vascular phase

• Cephalization: Vessels in upper chest is more prominent as a manifestation of pulmonary venous hypertension.

Hilar fullness with haziness:

Enlarge pulmonary veins with perivascular fluid collection leads to full hazy hilum.

Interstitial phase

• Kerley lines: 2-3 cm long lines in bases perpendicular to pleural surface. Due to increased lymphatic flow and fluid in interstitium.

Alveolar phase

• Basal congestion
• Pulmonary edema: Bilateral diffuse alveolar findings with butterfly distribution, air bronchograms and soft coalescing densities.

Pleural effusions

Rapid changes in CXR.

Q4: How do you distinguish CHF from ARDS in CXR?

• In ARDS the heart is normal in size and there are no pleural effusions.
• Clinical setting and the wedge pressure are necessary in some cases.