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Module title = Tutorial: Congestive Heart Failure
Lesson title = Pathophysiology
This is lesson 1 of 10 in this module
This module is not intended to be a comprehensive description of congestive heart failure (CHF). This module will focus on the basic pathophysiology of heart failure and how this relates to the findings on chest x-ray (CXR).
The common pathological factor in heart failure is that the
pressure in the left atrium is increased
. This can occur if the DIASTOLIC pressure in the left ventricle increases. The diastolic pressure in the left ventricle can occur for a variety of reasons and some of the more common reasons include:
myocardial ischemia
myocardial infarction
aortic valve stenosis or regurgitation
mitral valve regurgitation
chronic hypertension
less common:
any other cause of myocaridal disease (myocarditis, infiltrative disease such as amyloidosis and others)
constrictive pericarditis
pericardial tamponade
There are other causes of increased left ventricular pressure that are less common that will not be listed here.
There are also some causes of high pressure in the left atrium without high pressure in the left ventricle. The most common example of this mechanism is mitral stenosis.
We will describe the changes of heart failure by
working backwards from the left ventricle
to the lungs.
Sometimes, but not always, the increased diastolic pressure in the left ventricle will cause the left ventricle to dilate. This can be seen (and measured) on chest x-ray. We will explore this change (and the following changes) in detail in the following lessons in this module.
Moving backward from the left ventricle, we focus on the left atrium. The left atrium can dilate when the pressure in the left atrium is increased. This can also be seen on chest x-ray.
Moving backward from the left atrium, we are in the pulmonary veins (both right and left sides). These contribue to the "hilar vessels" on chest x-ray and when the increased pressure from the left atrium is transmitted to the pulmonary veins, they can also dilate and this can be seen on chest x-ray.
Moving backfrom from the pulmonary veins, we are in the smaller veins in the lung. These can also dilate and this can be seen on chest x-ray.
Moving backward from the veins, we are now in the capilaries and interstitial spaces of the lungs. Fluid can accumulate in the interstitial spaces in the lung parenchyma and this can be seen on chest x-ray.
In addition to the lung parenchyma, fluid can also accummulate in the wall of the large airways and cause them to become swollen. This can be seen on chest x-ray.
From the interstitial spaces, fluid can travel into the alveolar spaces of the lung and this can be seen on chest x-ray.
Finally, as fluid leaks into and then out of the lung tissue, it accummulates in the pleural spaces and creates pleural effusions which can be seen on chest x-ray.
The following lessons will each focus on each individual finding of CHF on CXR and will have practice sections to ensure your skill of CHF interpretation on CXR is properly demonstrated.
Lesson 1 of 10
That was the last lesson!