9. Heart Failure Flashcards
Define heart failure.
A state in which the heart fails to maintain an adequate circulation to meet the needs of the body.
What is the primary cause of HF?
Ischaemic heart disease - atheromatous plaque in coronary arteries
What 4 things affect cardiac output?
- Myocardial contractility - muscle function
- Venous capacity - preload
- Afterload - hypertension increases impedence
- Heart Rate - slight increase is more efficient but too fast decrease efficiency.
How does Starlings curve change in patients with severe HF?
Reduced contractility
Once past a certain point, increased filling doesn’t increase CO and it begins to decrease.
If filling too great -> oedema, dilation and worsened symptoms
What pathological changes occur in LV systolic dysfunction?
Thinning of myocardial wall
Dilitation - mitral valve incompetence
Neuro-hormonal activation
Risk of cardiac arrythmias
The SNS is activated in HF, how does this cause deleterious effects in the long term?
- Activates RAAS
- Increased HR and contractility leads to LV hypertrophy
- Vasoconstriction
- Direct cardiotoxicity causes myocyte damage
Which angiotensin receptor is responsible for inducing organ damage?
AT1 receptor
Why is RAAS commonly activated in HF?
- Reduced renal blood flow
2. SNS induction of renin
Which molecule is detected in blood tests to aid diagnosis of HF?
BNP - elevated in HF
What type of HF is associated with peripheral oedema?
Right-sided
What type of HF is associated with pulmonary oedema?
Left-sided
How does R-sided HF lead to peripheral oedema?
Back log from RA increases capillary hydrostatic pressure.
What is HF with preserved ejection fraction?
Reduced LV compliance and impaired myocardial relaxation.
- Thicker and shorter cardiomyocytes
- Increased deposition of collagen
What is impaired in HF with preserved ejection fraction?
Diastolic filling of LV - increased LA and PA pressure
Can lead to RV dysfunction
What symptoms are associated with L-sided HF?
fatigue, exertional dysoneoa, orthopnea, paroxysmal nocturnal dyspneoa
What clinical signs may appear as LVSD progresses?
Tachycardia
Cardiomegaly - displaced apex beat
Basal pulmonary crackles
Peripheral oedema
What are common causes of R-sided HF?
- Congestive lung disease
- Pulmonary embolism/hypertension
- L to R shunts
- Most frequent cause is secondary to left HF
What are the symptoms and signs of R-sided HF?
Fatigue, dyspneoa, anorexia, raised JVP, hepatic enlargement, putting oedema, ascites, pleural effusion
What is the name given to isolated HF due to lung disease?
Cor pulmonale
How does chronic lung disease cause right HF?
Ventilation-perfusion ratio:
In alveolar hypoxia, pulmonary vessels vasoconstrict to divert blood, ensuring ventilation matches perfusion. Increasing vascular resistance in the lungs means RV hypertrophies.
AngII has direct harmful effects in HF due to its action on which receptor?
AT1 receptor
How can HF result in hyponatraemia?
HF increases ADH release via RAAS, excess H20 absorption leads to hyponatraemia.
