Session 11 Flashcards
Define heart failure
A state in which the heart fails to maintain an adequate circulation for the needs of the body despite adequate filling pressure.
What are the causes of heart failure?
Ischaemic heart disease (main) Hypertension Dilated cardiomyopathy - bugs, alcohol, drugs, pregnancy Valvular/congenital heart disease Pericardial disease Arrhythmias
Describe the classification and progression of heart failure
Class I - no symptomatic limitation of physical activity
Class II - slight limitation of physical activity. No symptoms at rest.
Class III - less than ordinary physical activity results in symptoms
Class IV - symptoms at rest
When is right sided heart failure seen?
Rarely exclusive but seen in chronic lung disease, pulmonary embolism, valvular disease or L to R shunts. More commonly seen where left sided heart failure raises pulmonary arterial pressure leading to additional right sided failure (called congestive heart failure when it affects both sides).
What’re the signs and symptoms of left sided heart failure?
Fatigue, shortness of breath on exertion of lying flat (pulmonary oedema) Tachycardia Cardiomegaly (displaced apex beat) 3rd or 4th heart sound Basal pulmonary crackles
What are the signs and symptoms of right sided heart failure?
Peripheral oedema Fatigue Raised JVP Ascites Hepatomegaly
What systems are activated in heart failure to maintain cardiac output and what are the consequences?
Renin-angiotensin-aldosterone system (RAAS). Renin is released from the kidneys following the drop in blood pressure which catalyses the conversion of angiotensinogen to angiotensin I. ACE then converts angiotensin I to angiotensin II which is a vasoconstrictor and stimulates the release of aldosterone from the adrenal covered, increasing blood volume.
Sympathetic nervous system to cause vasoconstriction, increased heart rate and increased force of contraction of the heart.
These have the effect of making the already struggling heart work harder and angiotensin II can damage the heart.
Why is right sided heart failure associated with peripheral oedema?
Failure of the right side of the heart to pump effectively increases venous pressure and therefore capillary pressure. This favours the movement of water out of the capillaries.
Why does diastolic dysfunction also lead to heart failure?
Reduces filling of the heart (e.g. Reduced LV compliance) triggering the same neurohormonal systems.
What are the structural heart changes seen in heart failure?
Loss of muscle
Uncoordinated contraction (ECG changes)
Changes to the ECM (increased collagen)
Change of cellular structure and function (hypertrophy, SR dysfunction)
What brings about alterations in vascular tone in heart failure and what problems can it cause?
SNS, RAAS, decreased NO and increased endothelium that increase peripheral arterial resistance and exacerbate the clinical deterioration.
This can cause cachexia due to the reduced skeletal muscle blood flow and the glomeular filtration rate is reduced leading to a rise in serum urea and creatinine.
