Heart Failure Flashcards
Pathophysiology of HF? Discuss compensatory mechanism for HF.
(1. ) Inability of cardiac output to meet the physiological demands of the body.
(2. ) This can be systolic or diastolic failure. In both cases it causes pulmonary congestion
(3. ) Compensatory mechanisms (a-c) are activated in attempt to restore heart functioning, CO and tissue perfusion.
(a. ) Sympathetic Adrenergic Systems
- Inc HR + contractility
(b.) Myocyte size inc (LVH)
(c. ) Renal and peripheral alterations
- reduced GFR –> RAAS activation –> fluid retention –> Inc Preload and BP
- Peripheral vasoconstriction –> Inc resistance and thus BP
(4.) Chronic activation of compensatory mechanism can worsen HF and leads to cardiac damage. Thus CO declines, reduced tissue perfusion, hypoxic organs.
Systolic failure
- Inability of ventricles to contract normally so not enough blood is pumped out during systole
- Dec CO and dec EF (<40%)
- Causes: IHD, MI, Cardiomyopathy
Diastolic failure
- Inability of ventricles to relax and fill normally causing inc filling pressure
- Not enough blood fills into the ventricles during diastole - reduced preload.
- EF will look normal (>50%) despite SV being low. This is because EDV is low. Referred to as HF with preserved EF, HFPEF
- Causes: heart cannot relax and ventricle walls become stiffer. This can be due to:
- Less elasticity as we get older.
- Muscles get larger and thicker in high BP
- CAD
- Obesity
- Diabetes
- ventricular hypertrophy
- constrictive pericarditis
- tamponade
- reconstructive cardiomyopathy
Left-Sided SYSTOLIC HF pathophysiology?
(1. ) Systolic HF = heart can’t contract as forcefully and thus cannot pump efficiently.
(2. ) Dec BP -> dec renal blood flow -> activates RAAS -> inc blood volume -> inc preload which increases contractility via Frank Starling mechanism.
(3. ) H/E long term fluid retention in vessels causes leakage and build up in tissues.
(4. ) Eventually, LV function declines and will cause blood to back up into pulmonary circulation -> pulmonary congestion
(5. ) Fluid filled capillaries in lungs can rupture, leaking blood into the alveoli.
(6. ) Alveolar macrophages engulf leaking RBC, which causes them to become brownish colour from iron build-up, these are called “hemosiderin-laden macrophages”, also known as “heart failure cells”.
Clinical features of left-sided HF
Signs of LV pump dysfunction
(1. ) Dyspnea - trouble breathing
(2. ) Orthopnea: difficulty breathing when lying down flat
(3. ) Fatigue
(4. ) Exercise intolerance
Signs of volume overload
(1. ) Pulmonary Crackles - heard on auscultation while patient breathes.
(2. ) Peripheral oedema
Aetiology of left-sided systolic HF
(what causes LV to become weaker?) [3].
- IHD (most common cause) E.g. CAD, atherosclerosis
- Longstanding HTN
- Dilated cardiomyopathy
Left-Sided DIASTOLIC HF pathophysiology?
(1. ) This is a filling dysfunction but LV function is preserved
(2. ) LV can no longer relax and becomes stiff.
(3. ) LV is stiff - dec compliance and impaired relaxation this causes increased resistance to filling (reduced EDV). So little blood leaves the ventricles (reduced SV). EF is preserved.
(4. ) There is an inc EDP and this can impact pulmonary circulation and lead to pulmonary congestion, dyspnea, and other symptoms of heart failure
Aetiology of left-sided diastolic HF (what makes it stiffer?) [4].
(1. ) Chronic HTN (most common cause)
- LVH: reduces cardiac compliance and reduces EDV
(2. ) Aortic stenosis
- AS reduces blood flow through aortic valves so there is an increase afterload and so heart has to work with more force and causes LVH.
(3. ) Hypertrophic cardiomyopathy
- Heart becomes abnormally thick
(4. ) Restrictive cardiomyopathies
- heart gets stiffer and less compliant
- LV can’t easily stretch and fill with as much blood.
Why might you get arrhythmias in HF? and how would it be managed?
(1. ) In HF, myoctes stretch and thin out, or thicken and become ischaemic. This can lead to arrhythmias.
(2. ) Ventricles don’t contract in sync anymore making them less able to pump out blood.
(3. ) Mx = cardiac resynchronization therapy pacemakers
- stimulate ventricles to contract at same time and improve blood pumped out.
Aetiology of Right-sided HF (3)
(1. ) Left-sides heart failure
- When LV fails, increased fluid pressure is, in effect, transferred back through the lungs, ultimately damaging the right side
(2. ) Atrial or ventricular septal defect
- left-to-right cardiac shunt allows blood to flow from left to right side down pressure gradient, which inc fluid volume on right side and can lead RVH
(3. ) Chronic lung disease, Cor Pulmonale
- Lung diseases make it harder to exchange oxygen - hypoxia
- In response to hypoxia, pulmonary arterioles constrict, which raises pulmonary BP
- High BP in pulmonary circulations makes it harder for RV to pump against and can lead to RVH and HF.
- Chronic lung disease leading to RVH and failure is known as cor pulmonale.
Clinical Features of Right-sided HF (5)
(1. ) Jugular venous distention
(2. ) Hepatosplenomegaly
(3. ) Cardiac Cirrhosis and liver failure
(4. ) Ascites
(5. ) Pitting Oedema
How may you get Biventricular HF?
- Both ventricles are affected.
- RSHF is often caused by LSHF
- Inc pulmonary arterial BP makes it harder for the right side to pump blood into pulmonary circulation.
Aetiology of LSHF & RSHF
Causes of left-sided HF
- CAD, HTN, valve disease, myocardial disease
Causes of right-sided HF
- LSHF, valve disease, lung disease
Other causes:
- Dilated CM, hypertrophic CM
- Renal failure
- Haemochromatosis
Signs and Symptoms of LSHF & RSHF
Left Sided HF Symptoms:
- Dyspnoea
- Orthopnoea
- Paroxysmal nocturnal dyspnoea
- Pink sputum caused by pulmonary oedema.
- Exercise intolerance
Right Sided HF Symptoms
- Jugular venous distention
- Hepatomegaly
- Ascites
- GI upset: N+V
- Pitting Oedema in lower extremities
Describe severity of HF using New York Classification
(1. ) Class 1 = Heart disease present but no undue dyspnoea from ordinary activity
(2. ) Class 2 = Comfortable at rest, dyspnoea during ordinary activities
(3. ) Class 3 = Less than ordinary activity causes dyspnoea, which is limiting
(4. ) Class 4 = Dyspnoea present at rest, all activity causes discomfort
