Overview
This is described as
“Chronic heart failure (or congestive heart failure) may be defined as a chronic inability of the heart to maintain adequate perfusion of the tissues at a normal filling pressure” This is a more general condition and is most useful as a connecter of its causes to its outcomes. You can have left and right heart failure and bilateral heart failure
Better understanding CHF
An analogy used in lectures is that chronic heart failure is like a failing pump. The pump could be broken for a few reasons : it could be physically broken, just doesnt function, or it could be overloaded
Pump broken:
- Infarction
- Cardiomyopathy
- Myocarditis
Pump not functioning
- Arrhythmia
- Valvular disorder
- Pericarditis
Pump overloaded
- Hypertension
- High output (Anaemia, Graves disease)
Pathogenesis
In a lot of the causes given you see an increase in cardiac work (stenosis, HTN, high output), this can cause the Left ventricle to put on more muscle, to pump harder. This is called hypertrophy. This will increase its ability to pump but has its own problems. The muscle is capable of outgrowing its blood supply and this can lead to ischaemia, which can lead to angina and infarction (esp with atherosclerotic plagues). This can then lead to heart failure but hypertrophy in itself, over years, can lead to fatigue in the heart and slow failure in its own right.
Clinical
Causes
There are many causes but it mostly breaks down into something that reduce cardiac output by 1. reducing muscle in the heart, 2. functional difficulties in pumping, or 3, overload leading to failure. Specific causes are listed.
Muscle death
- Infarct
- Cardiomyopathy
- myocarditis
Functional difficulties
- Arrhythmia
- Stenosis
- Pericarditis
Overload
- Hypertension
- High output
Consequences
There are many consequences as there is much the heart and blood does.
The general effects are listed as headings and explained under:
Decreased perfusion
The decreased perfusion will lead to doecreased exercise tolerance (get tired faster) Decreases exercise tolerance can lead to lifestyle changes and possible institutionalisation.
Lungs
Blood backed up into the lungs leads to pulmonary oedema and shortness of breath
Right Heart failure
blood backed up into the lungs will back up into the right heart. this will lead to venous congestion, oedema, etc
Dilatation
This will lead to poorer contraction (further leading to CHF) as per starlings curve we see this means worse contractility
Complications
Treatments
For this condition prevention is key, if the causes are appropriately managed then heart failure will rarely develop, as this is a condition that takes years to develop.