Chronic Heart Failure Flashcards
What is the definition of heart failure?
Cardiac output is inadequate for the body’s requirements.
Why is mild myocardial dysfunction not associated with decreased cardiac ouput?
CO is maintained by an increase in venous pressure (and hence diastolic volume)
What is systolic heart failure?
Inability of the ventricle to contract normally, resulting in decreased CO. The ejection fraction is < 40%
What is the ejection fraction in systolic HF?
<40%
What are causes of systolic HF?
- IHD
- MI
- Cardiomyopathy
What is diastolic HF?
Inability of the ventricle to relax and fill normally, causing increased filling pressures. EF >50%
What can cause diastolic HF?
- Constrictive pericarditis
- Tamponade
- Restrictive cardiomyopathy
- HTN
What is important to note about systolic and diastolic HF?
They often co-exist
What is acute HF?
Term used to mean new onset acute or decompensation of chronic heart failure characterised by pulmonary oedema +/- peripheral oedema with or without signs of peripheral hypoperfusion
What is chronic HF?
HF that develops or progresses slowly. Venous congestion is common but arterial pressure is well maintained until late
What is low-output HF?
Cardiac output is decreased and fails to increase normally with exercise
What are causes of low-output HF?
- Pump failure
- Excessive preload
- Chronic excessive afterload
What causes of pump failure can cause low-output HF?
- Systolic +/- diastolic HF
- Decreased HR - B-blockers, heart block, post MI
- Negatively inotropic drugs
What are causes of excessive preload in low-output HF?
- Mitral regurgitation
- Fluid overload/retention
What are causes of chronic excessive afterload in low-output HF?
- Aortic stenosis
- Hypertension
What is high output HF?
Output is normal or increased in the face of greatly increased metabolic demand or shunting of blood which increases myocardial demand.
Cardiac failure occurs when CO fails to meet these increased needs. It will occur with a normal heart, but even earlier if there is heart disease
What are causes of high output cardiac failure?
- Anaemia
- Pregnancy
- Hyperthyroidism
- Paget’s disease
- AV malformation
- Beri Beri
What are features of RHF?
- Peripheral oedema
- Ascites
- Nausea
- Anorexia
- Facial engorgement
- Pulsation in the neck
- Epistaxis
What are features of LHF?
- Dyspnoea
- Poor exercise tolerance
- Fatigue
- Orthopnoea
- PND
- Nocturnal cough +/- pink frothy sputum
- Wheeze
- Nocturia
- Cold peripheries
- Weight loss/Muscle wasting
How is CO maintained in mild/moderate myocardial dysfunction?
Increased venous return plus sinus tachycardia - this is in the context of decreased ejection fraction. In more severe cardiac dysfunction, CO is maintained by more marked venous return and tachycardia
What does increased venous pressure cause both at organ and system level?
- Pulmonary oedema
- Hepatic enlargement/congestion
- Ascites
- Peripheral oedema
- Increased JVP
What pathophysiological changes occur in HF?
Why does salt and water retention occur in cardiac failure?
Increased venous pressure occurs when the ventricles fail. Reduced cardiac output also leads to diminished renal perfusion, activating RAAS, which promotes salt and water retention, which further increases venous pressure. Afterload is also increased by a combination of RAAS activity and Adrenergic activation
What is atrial natriuretic peptide released in response to?
Atrial stretching
What is the action of ANP?
- Diuresis
- Natriuresis
- Vasodilatation
- Suppression of RAAS
What is brain natriuretic peptide?
NP predominantly secreted by the ventricles, and has an action similar to that of ANP but greater diagnostic and prognostic value
What is the difference in ejection fraction between systolic and diastolic HF?
- Systolic <40%
- Diastolic >50%
What are the main symptoms of HF?
- Exertional dyspnoea
- Orthopnoea
- Paroxysmal nocturnal dyspnoea
- Fatigue
What are signs of heart failure?
- Cardiomegaly
- Third and fourth heart sounds
- Elevated JVP/hepatojugular reflux
- Tachycardia
- Hypotension
- Bi-basal crackles
- Cool peripheries
- Narrow pulse pressure
- Pulsus alternans
- Pleural effusion
- Peripheral ankle oedema
- Ascites
- Tender hepatomegaly
- Wheeze
- Murmurs
- Cyanosis
- Weight loss
Why would you get cardiomegaly on CXR in heart failure?
Dilation of the heart atria and ventricles
Why would you get an S3 heart sound in HF?
In heart failure with systolic dysfunction there is elevated atrial pressure. When the mitral valve opens there is rapid filling down the pressure gradient into the stiffened dysfunctional ventricle.
Why would you get an S4 heart sound in HF?
Forceful contraction of the atrium pushes blood into a non-compliant left ventricle. The sudden deceleration of blood against the stiff ventricular wall produces a low-frequency vibration, recognised as the fourth heart sound.
Why would you get an elevated JVP in HF?
Peripheral veins are abnormally constricted - due to increased tissue oedema and sympathetic stimulation, which increases the blood volume in the central venous system
Volume overload – leads to increased ventricular end-systolic/diastolic volume and pressure, which in turn backs up into the jugular veins
Right ventricular systolic failure – leads to increased end-systolic pressure, which is transmitted back into the venous system
Right ventricular diastolic failure - increased stiffness causes pressure to ‘back-up’ into the venous system
What are causes of a raised JVP?
- PE, Pericardial effusion, PS, PHT
- Quantity overload - RVF
- SVC obstruction
- Tamponade, TR
Why would you get tachycardia in HF?
This is the body’s attempt at maintianing cardiac output as stroke volume decreases with progressively failing myocardium
What causes Bi-basal crackles in HF?
Pulmonary oedema - In left heart failure, raised left ventricular and atrial pressures back up into the lung vasculature. When pulmonary vasculature pressure increases above 19mm Hg, a transudate of fluid enters the lung interstitium and alveoli. The alveoli are filled with fluid and collapse. When the patient breathes in, the alveoli are filled with air and ‘pop’ open, causing inspiratory crackles.