What is heart failure?
Heart failure is a state in which the heart fails to maintain an adequate circulation for the needs of the body despite an adequate filling pressure
Outline the aetiology of heart failure
- Ischaemic Heart Disease
- Dilated/hypertrophic Cardiomyopathy
- Valvular/Congenital Heart Disease
- Pericardial disease
What are the clinical signs of chronic heart failure?
- Pulmonary congestion
- Venous congestion
- Dependent oedema
What are the symptoms of chronic heart disease?
Describe the clinical features of Class I heart failure
No symptomatic limitation of physical activity
Describe the clinical features of Class II heart failure
- Slight limitation of physical activity
- Ordinary physical activity results in symptoms
- No symptoms at rest
Describe the clinical features of Class III heart failure
- Marked limitation of physical activity
- Less than ordinary physical activity results in symptoms
- No symptoms at rest
Describe the clinical features of Class IV heart failure
- Inability to carry out any physical activity without symptoms
- May have symptoms at rest
- Discomfort increases with any degree of physical activity
What are the factors affecting cardiac output?
- Heart rate
- Venous capacity (preload)
- Myocardial contractility
- Arterial and peripheral impedance (afterload)
What is Starling's Law of the Heart?
"The force developed in a muscle fibre depends on the degree to which the fibre is stretched."
Describe the pathophysiology of Left Ventricular Systolic Dysfunction
- Increased LV capacity
- Reduced LV cardiac output
- Thinning of the myocardial wall
I. Fibrosis and necrosis of myocardium
II. Activity of matrix proteinases
What are the causes of Left Ventricular Systolic Dysfunction?
- Mitral valve incompetence
- Neuro-hormonal activation
- Cardiac Arrhythmias
Which structural heart changes occur after Left Ventricular Systolic Dysfunction?
- Loss of muscle
- Uncoordinated myocardial contraction
- Changes to the ECM (increase in collagen)
- Change of cellular structure and function (myocyte hypertrophy)
Describe ventricular remodeling after acute infarction
Describe ventricular remodeling in diastolic and systolic heart failure
Label the following images:
Identify the 5 different pathways for neuro-hormonal activation
- Sympathetic Nervous System
- Renin-Angiotensin-Aldosterone System
- Natriuretic Hormones
- Anti-Diuretic Hormone
Why is SNS stimulated in heart failure?
Early compensatory mechanism to improve cardiac output:
- Cardiac contractility
- Arterial and venous vasoconstriction
Outline the long-term deleterious effects of the SNS in heart failure
When is RAAS commonly activated in heart failure?
- Reduced renal blood flow
- SNS induction of renin from macula densa
Outline the action of RAAS in heart failure
In terms of the brain, blood vessels, heart and kidney, explain how Angiotensin II plays a key role in organ damage
When are natriuretic peptides released in heart failure?
- Atrial distension
- Increased blood volume and pressure
Outline the action of natriuretic peptides in heart failure
Outline the effect of ADH (vasopressin) in heart failure
ADH is increased in heart failure:
- Increased H2O retention
- Tachycardia and increased TPR → increased CO
Outline the action of endothelin in heart failure
- Endothelin is secreted by vascular endothelial cells resulting in renal vasoconstriction via autocrine activity
- Activates RAAS (increased levels in some patients with heart failure)
Outline the effect of other chemicals in heart failure:
- Prostaglandin E2 and I2
- Nitric oxide
- Prostaglandins: vasodilators stimulated by NA and RAAS to counter their effects
- Nitric oxide: potent vasodilator produced by endothelial cells via NO synthase (NO synthase may be blunted in HF)
- Bradykinin: promotes natriuresis, vasodilatation and stimulates production of PGs
What is oedema?
- Oedema is the excessive volume of fluid within the tissues (interstitial / intracellular) which can occur due to changes in capillary dynamics
- It is often seen in heart failure as there is increased capillary hydrostatic pressure
Vascular endothelium increases in peripheral arterial resistance.
Why is this?
- Reduced NO
- Increased endothelin
Changes in vascular endothelium leads to skeletal muscle changes.
- Reduced skeletal muscle blood flow
- Reduction in skeletal muscle mass (cachexia)
- Abnormalities of structure and function
Describe the renal effects associated with changes in the vascular endothelium
- GFR is maintained in early HF by haemodynamic changes at the glomerulus – increased Na+ /H2O retention due to neurohormonal activation
- GFR falls in severe HF due to reduced renal blood flow leading to a subsequent rise in serum urea and creatinine
Describe the multi-factorial aetiology of anaemia associated with vascular endothelium changes
- Chronic inflammatory disease
- Expanded plasma volume
- Drug therapy (ACEi / Aspirin)
- Iron malabsorption
- Chronic renal failure
Heart Failure with Preserved Ejection Fraction (HFpEF) occurs in almost 50% of heart failure patients.
Describe the clinical features of this condition
- Frequently elderly and female
- Often history of hypertension / diabetes / obesity
- Normal LV function with concentric remodelling
In four steps, describe the pathophysiology of HFpEF
⇒ Reduced LV compliance and impaired myocardial relaxation
⇒ Impaired diastolic LV filling (dependent on high LA pressure)
⇒ RV dysfunction results from high LA and PA pressure
⇒ Triggers neuro-hormonal activation as per systolic heart failure
Identify the 5 clinical syndromes of heart failure
- Left Sided Heart Failure
- Right Sided Heart Failure
- Congestive cardiac failure
- LVSD (pump failure)
- HFpEF (failure of LV relaxation)
Identify the symptoms of Left Sided Heart Failure
- Exertional dyspnoea
- Paroxysmal nocturnal dyspnoea (PND)
What are the clinical signs of Left Sided Heart Failure?
- Cardiomegaly (displaced apex beat)
- 3rd or 4th heart sound (‘Gallop rhythm’)
- Functional murmur of mitral regurgitation
- Basal pulmonary crackles (fluid in the lungs)
- Peripheral oedema
Describe the aetiology of Right Sided Heart Failure
- Chronic lung disease
- Pulmonary embolism / pulmonary hypertension
- Pulmonary/tricuspid valvular disease
- Left-to-right shunts (ASD/VSD)
- Secondary to left heart failure (most frequent)
What are the signs and symptoms of Right Heart Failure?
- ↑ JVP
- Pitting oedema
- Pleural effusion
What is congestive (biventricular) heart failure?
- Congestive heart failure is a chronic progressive condition in which the heart's function as a pump is inadequate to meet the body's needs
- Both the right and left sides of the heart fail to pump adequately, hence, the signs and symptoms of both right and left heart failure develop