Heart Failure

Heart Failure

Background

·        = Pump function is inadequate to maintain body homeostasis ® Na and H20 retention

·        ­ Left atrial pressure above 25 mmHg ® transudate of ECF into alveoli ® pulmonary oedema

·        20% have infarcts without knowing it

·        Strong association with old age.  A common diagnosis amongst the most disabled elderly

·        Symptoms may be non-specific: ¯energy, nausea, poor appetite, poor mobility, confusion, ¯sleep etc

Classification

·        Classify as:

o   High output failure: due to ­O2 requirements and heart can‟t keep up. Happens quicker if pre-existing heart disease. Eg anaemia, pregnancy, hyperthyroidism, Paget‟s disease. Initial features of RH failure. Progresses to LH failure

o   Low output failure: Inadequate output (ejection fraction < 0.35 – 0.40) or only adequate with high filling pressure:

§  Excessive preload: eg mitral regurgitation or fluid overload

§  Pump failure due to heart muscle disease, restricted filling, inadequate heart rate (eg heart block, post MI)

§  Chronic excessive afterload (eg aortic stenosis, hypertension)

·        Can also classify as diastolic dysfunction (eg poor filling due to, for example, tamponade or restrictive cardiomyopathy) or systolic dysfunction (eg poor contraction due to a large floppy heart)

·        Left HF ® pulmonary oedema:

o   Caused by:

§  Ischaemic heart disease

§  Hypertension

§  Aortic and mitral valve disease (aortic stenosis/rheumatic heart disease)

§  Myocardial disease 

§  Hypertrophied L ventricle ® secondary atrial enlargement ® atrial fibrillation

o   Leads to:

§  ¯Renal flow ®Na retention ® oedema

§  Pulmonary hypertension ® pulmonary oedema and bronchospasm

o   Symptoms: exertional dyspnoea, orthopneoa, PND, wheeze („cardiac asthma‟), cough + pink froth, haemoptysis, fatigue

o   Signs: tachypnoea, tachycardia, end-inspiratory basal crackles, dullness to percussion over lung bases, S3, cardiomegaly, cyanosis, pleural effusion

·        Right HF:

o   Due to:

§  Left Heart failure ® pulmonary hypertension ® RV failure

§  Cor pulmonale (R ventricle ↑ pressure due to disease of lung or pulmonary vasculature)

§  Constrictive pericarditis

o   Leads to:

§  Symptoms: fatigue, abdominal pain, oedema, anorexia, wasting, weight gain

§  Signs: enlargement of liver, spleen, kidneys, subcutaneous tissues and brain ® ­JVP, pulsitile liver, hepatomegaly, pitting oedema, ascites

·        Congestive HF: both sides

Aetiology

·        Age associated changes:

·        Reduction in b adrenergic responsiveness ® ¯inotropic response and ¯vasodilation

o  Increased arterial stiffness ® ¯compliance ® ­afterload

o  Alterations in cardiac filling: ­connective tissue content of myocardium ® stiffer ventricle ® filling more dependent on atrial contraction ® ­pressure and size of left atrium ® predisposes to AF (® further filling problems)

o  Failure of reserve capacity of mitochondria

·        Age associated diseases:

o  Hypertension ® risk factor for atherosclerosis, and ­size and stiffness of left ventricle. By the time they have heart failure, may no longer have hypertension as they can‟t sustain the cardiac output necessary to be hypertensive

o  Coronary artery disease

o  Also ¯respiratory function and ¯renal function

·        Precipitating factors unmask the subsequent reduced cardiac reserve, eg arrhythmia, infarction, AF, infection, thyroid disease, anaemia, PE, COPD ® hypoxia, DRUGS, etc

·        Decreased perfusion due to decreased pump action ® ↓kidney perfusion ® ↑renin/aldosterone ® ↑blood volume to try and increase pre-load and push heart up the starling curve (however, they‟re often into negative marginal gain from increased volume). However, ↑ BP also raises after-load and increases work of the heart ® ↑ischaemia

·        Cardiac dysfunction due to:

o  Disruption of circulatory system

o  Disorders of conduction

o  Lesion preventing valve opening

o  Pump failure (contraction/dilation) ® ↓SV and ↑EDV ® ↓CO

·        Beriberi = heart failure due to deficiency of Vitamin B1 (Thiamine): bradycardia, premature ventricular beats, VF, AF, and heart block

Differential

·        Must be able to prove the heart is the problem

·        Otherwise consider:

o  Renal failure (eg nephritic syndrome) ® oedema

o  Liver disease or malnutrition ® ¯albumin ® oedema

Investigations

·        Bloods: FBC, Cr, electrolytes, Trop I, U&E, glucose, TFTs, LFTs, Cholesterol, ?ABG

·        ECG

·        CXR: although concomitant COPD may obscure changes in heart size and pulmonary vasculature

·        Echocardiogram:

o  LV hypertrophy (normal thickness 1 cm), valve regurgitation or stenosis (check rate of flow), areas of hypokinetic myocardium

o  Normal velocity of blood through the heart = 1 m/sec. If aortic valve narrowed then faster flow then > 3 m/sec (same amount of blood through smaller space). Velocity between ventricles and aorta is proportional the change in pressure

·        Angiography

Treatment

·        Principles:

o  Reverse underlying process (eg thyrotoxicosis)

o  Halt progression

o  Help symptoms

·        Acutely:

o  Treat cause if any: hyperthyroid, hypertension, anaemia, alcohol, valve lesions

o  Symptomatic treatment:

§  Sitting position ® ¯venous return

§  O2 therapy (care with CO2 retainers)

o  Frusemide 40 – 80 mg iv (if not already on it) ® ¯afterload, vasodilation (¯preload and ¯ECF volume). Watch for ¯K+

o  Morphine 5 – 10 mg iv: (as long as not low BP) a potent vasodilator (↓preload ® ¯work of heart and ↓pulmonary capillary pressure), bradycardic and sedative effects

o  Also consider:

§  Aminophyline 250 mg over 5 – 10 min (+ive inotrope, mild diuretic, ¯bronchospasm. iv form of theophylline)

§  Blood pressure control: Nitrates, Oral ACE inhibitors (¯preload and afterload, and ­heart remodelling)

§  Arrhythmia control: Digoxin, amiodarone

§  Inotropes: dopamine, dobutamine

§  DVT prevention

§  Not b-blocker acutely, but ­use in chronic management

o   Intensive treatment:

§  Mechanical ventilation with positive end-respiratory pressure (CPAP) ® ¯preload and ­intra-alveolar pressure

§  Aortic balloon pump

§  Heart transplant

o   Monitoring: weight, fluid balance, telemetry and U&Es (eg ¯K)

·        Chronic:

o   Balancing act, especially in elderly: eg risks of polypharmacy, comorbid disease, what is the goal of treatment, postural hypotension if over-treated ® falls, etc

o   Non-drug treatment:

§  Stop smoking

§  Control of blood pressure, DM, ¯alcohol

§  Exercise within ability to tolerate it (prevent further deterioration and problems of immobility)

§  Dietary advice: ¯weight, ¯Na and H2O depending on weight (ie educate patient about illness and to monitor weight daily), low fat, high calorie

§  Physio: mobilisation and breathing control

§  Vaccination against influenza and pneumococcus

o   „Core‟ drugs:

§  ACE Inhibitors: Drug of first choice in CHF. ¯dyspnoea, ­exercise tolerance, ¯mortality, ¯admissions. Even if low blood pressure

§  Diuretics: for all people with volume overload and CHF. In elderly, effect of loop diuretics may be delayed through poor absorption, and ¯elimination ® ­effect. Accumulation can ® deafness. Limited if poor renal perfusion. May exacerbate urinary incontinence. Low dose spironolactone may be useful (if high dose and ACE inhibitor ® ­K and ¯renal function)

§  Aspirin

o   Second line drug treatment for systolic dysfunction:

§  b-blockers, used cautiously, are gaining wider use:

·        If ­sympathetic drive is causing a relative tachycardia then b-blockers will help (will get worse on b-blockers if reliant on sympathetic drive to maintain CO)

·        Criteria: chronic, stable, LV systolic impairment (ejection fraction < 45%), resting HR > 50 bpm, no contraindications (eg asthma, AV block). Not if very low ejection fraction

·        Start at low dose, titrate up as out-patient with carvedilol (a + b blocker) or metoprolol

·        Clear instructions to patient of symptoms of deterioration

·        See Clinical Use of Beta-Blocker Therapy in Patients with Heart Failure, Doughty RN and Richards AM, NZMJ, 9 Feb 2001

§  Spironolactone

§  Other Vasodilators (e.g. nitrates, calcium channel blockers) - ¯work of heart, ­efficiency of heart, peripheral redistribution of blood. But problems with postural hypotension (especially if already volume depleted – check for hyponatraemia)

§  Inotropic agents if low BP, eg digoxin.  Controversial in heart failure, main role is in AF

§  Limited role for anti-arrhythmic agents

o   Drug treatment for diastolic dysfunction (ie normal ejection fraction):

§  Avoid over diuresis

§  Tolerate AF poorly

§  Aspirin

§  b-blockers

o   Statins if cholesterol > 4 mmol/l