Treatment For Heart Failure

11.9.06

Common causes of chronic heart failure
• Myocardial dysfunction:
-hypertension - asymptomatic;
-IHD;
-cardiomyopathies eg. alcohol.
• Valvular heart disease:
-stenosis - congenital;
-incompetence.
• High output states.

Common causes of acute heart failure
• Acute myocardial dysfunction:
-cardiogenic shock after MI;
-myocarditis.
• Acute valve defects:
-rupture in infective endocarditis.
• Altered rhythm:
-fast - poor filling = low CO = shock;
-slow - low rate = low CO = shock.
• Massive pulmonary embolism.

Left, right or both?
• Distinguish left- and right-sided failure.
• Biventricular failure and left heart failure common.
• Isolated right heart failure less common ("cor pulmonale").

Prevention better than cure
• Detect and effectively manage high blood pressure.
• Smoking, diabetes mellitus and other vascular risk factors.
• Alcohol.

Symptoms of left heart failure
• Chronic:
-dyspnoea, orthopnoea and paroxysmal nocturnal dyspnoea;
-cough and wheeze;
-malaise.
• Acute:
-same, plus…
-symptoms of low blood pressure;
-cough - frothy, pink sputum - haemoptysis.

Signs of left heart failure
• Fine basal crackles.
• Third/fourth heart sound (or both - "gallop rhythm").
• Central cyanosis.
• Low blood pressure, if problem acute.

Symptoms of right heart failure
• Chronic (usually in presence of left heart failure):
-peripheral swelling (dependent parts).
• Acute (eg. after massive pulmonary embolism):
-hepatic pain.

Signs of right heart failure
• Pitting oedema of legs and sacrum.
• Raised JVP.
• Hepatomegaly.
• Ascites.

Prognosis and aims of treatment
• 5-year survival rate with left ventricular failure as bad as many cancers.
• Save life in acute circumstance.
• Relieve symptoms.
• Prolong life.

Differential diagnosis
• Left heart failure:
-asthma;
-pneumonia.
• Right heart failure:
-chronic liver disease.

Initial investigation
• Biochemistry and haematology:
-renal impairment, albumin, thyroid function and haemaglobin.
• Chest X-ray:
-cardiac size, presence of pulmonary oedema/effusions.
• ECG:
-cardiac size and evidence of muscle disease.
• Echocardiography:
-dimensions, valve function.

Drugs for heart failure
• Diuretics.
• Vasodilators.
• Inotropic agents.
• [Beta blockers.]

Loop diuretics: mode of use
• Potent naturesis and diuresis.
• Steep dose-response curve.
• Given IV for acute pulmonary oedema - symptoms may be ameliorated within 30 minutes.
• Given orally (often twice daily) in "maintenance" treatment of congestive cardiac failure.
• Eg. frusemide.

Adverse effects
• Severe dehydration.
• Hypokalaemic metabolic alkalosis.
• Hypomagnesaemia.
• Ototoxicity.
• Hyperuricaemia and gout.
• Decreased glucose tolerance.

Potassium-sparing diuretics eg. spironolactone
• Antagonists of aldosterone.
• Not usually potent enough alone.
• Usually + loop diuretic.
• Reduce mortality (+ACE inhibitor and loop diuretic).
• Adverse effects:
-hyperkalaemia;
-gynaecomastia.

Vasodilators: ACE inhibitors
• ACE converts A1 to A2.
• A2 = arteriolar constrictor.
• A2 increases adrenaline release from adrenal medulla.
• A2 causes aldosterone release (hence, salt retention).
• Lower preload and afterload by blocking synthesis of A2.
• Eg. enalapril.
• No parenteral formulation - used orally in chronic left/biventricular heart failure.
• Adverse effects include:
-renal failure (especially in renal artery stenosis);
-chronic cough;
-hypotension (especially with first dose).

Inotropic drugs
• Most commonly needed after large MI with "cardiogenic shock."
• Low blood pressure, poor renal/splanchnic perfusion; acute renal failure.
• High mortality rate.
• Eg. dobutamine.
• Given IV with very short half-life therefore infusion rate determines plasma concentration.
• Lower infusion rates increase contractility and CO.
• Higher infusion rates: arterial constriction (and tendency to reduced splanchnic perfusion).

Beta blockers
• Negatively inotropic - make CCF worse if used incautiously.
• But, have other actions too (including anti-arrhythmic).
• And reduce mortality in patients on treatment with diuretic and ACE inhibitor.
• Eg. carvedilol.