II. Pathophysiology: Progression of chronic CHF
- Stage I: Pulmonary venous Hypertension with prominent upper lobe vessels (cephalization)
- Stage II: Interstitial Infiltrates (Kerley B Lines, peribronchial cuffing)
- Stage III: Alveolar Infiltrates (and Pleural Effusions)
- Interstitial fluid leak overwhelms lymphatic drainage capacity, overflowing into alveoli and pleural space
- Acute Pulmonary Edema typically presents with Stage III findings (without stage I or II)
III. Imaging: Stage I CHF XRay findings - Vascular phase - pulmonary venous Hypertension
- Cardiomegaly
- Pulmonary vasculature redistribution (Cephalization)
- Upper pulmonary vasculature becomes more prominent (upright Chest XRay)
- Normal, healthy patients have prominent lower lung field vasculature in contrast (upright Chest XRay)
- Redistribution will not be seen on supine xray
- Test Specificity: 80-90% for increased ventricular filling pressure
- Increased artery to Bronchus ratio
- Perihilar and upper lobe arteries (white round densities)
- Normally smaller in cross-section than Bronchi (dark round densities)
- Pulmonary vascular redistribution
- Results in an increased pulmonary artery diameter, larger than the bronch (ratio >1)
- Perihilar and upper lobe arteries (white round densities)
- Vascular pedicle broadens
- Mediastinal width increases at the level of the aortic arch or knob
- Pulmonary capillary wedge pressure (PCWP): 13-18 mmHg
IV. Imaging: Stage II CHF XRay findings - Interstitial phase
-
Kerley B Lines (Interstitial Infiltrates)
- Short (1-2 cm) peripheral, lower lobe white lines, perpendicular and adjacent to pleura
- Peribronchial cuffing
- Bronchial wall thickening from Interstitial Edema (white rim around dark Bronchioles)
- Vessels become less distinct
- Hazy contours result from surrounding edema (perihilar haze)
- Interlobar fissure thickens (brighter white line between the lung lobes)
- Pulmonary capillary wedge pressure (PCWP): 18-25 mmHg
V. Imaging: Stage I CHF XRay findings - Alveolar phase
-
Alveolar Infiltrates (Cottonwool appearance)
- Congestion is most dramatic centrally and in basal regions (bat-wing or butterfly appearance)
- Acute Pulmonary Edema (e.g. acute Left Ventricular Failure) may present with diffuse white-out appearance
-
Air Bronchograms
- Dark Bronchioles become prominent in a background of white, fluid filled alveoli
- Pleural Effusion
- Pulmonary capillary wedge pressure (PCWP): >25 mmHg
VI. Imaging: Other findings
- Underlying lung disease
- Chamber enlargement
- Valve calcifications
VII. Differential Diagnosis
-
Acute Respiratory Distress Syndrome (ARDS)
- History of major trigger (e.g. Trauma or surgery)
- No cardiomegaly
- No Pleural Effusions
VIII. Efficacy: CHF findings on Chest XRay
- Most useful initial test to assess for Congestive Heart Failure (as well as other causes of Dyspnea)
- Test Sensitivity: 71%
- Test Specificity: 92%
IX. Resources
- Congestive Heart Failure (Loyola Stritch School of Medicine)
- Cremers, Bradshaw and Herfkens, Chest X-Ray - Heart Failure (Radiology Assistant)