In this article, we will discuss the Management of Left Ventricular Failure. So, let’s get started.
1. Measure to reduce preload
• Upright or prop up posture of the patient on the bed with legs dangling along the side of the bed, if possible. This reduces venous return.
• Morphine is used to relieve anxiety
and dyspnoea. It is given I.V. in dosage of 5–10 mg with an antiemetic (metoclopramide 10 mg IV.) and
repeated frequently as desired. This
drug leads to arteriolar and venous
dilatation (capacitance vessels) thereby reduces venous return (preload). Naloxone (an antidote to morphine) should be available in case respiratory depression occurs.
2. Measures to lower pulmonary capillary wedge pressure
• Oxygenation: There is arterial hypoxaemia due to lowered oxygen diffusion as a result of alveolar oedema, hence, 100% O2, should be given through the mask preferably under positive pressure (it will stop transudation of fluid into alveoli by reducing venous return and thereby lowering pulmonary capillary pressure). Positive pressure ventilation has been found beneficial in refractory cases of pulmonary oedema.
• Bronchodilatation: Sometimes aminophylline (theophylline ethylenediamine), 240 to 480 mg given I.V. is effective in relieving bronchospasm, and in addition may lower pulmonary venous pressure. It has also a mild diuretic and positive inotropic effect (augments myocardial contractility).
• Inotropic and inodilators: The inotropic agents (dopamine, dobutamine) and inodilator (milrinone) are indicated in cardiogenic pulmonary oedema with
severe L.V. dysfunction.
• Diuretics: The high potency loop
diuretics such as fursemide (40–100 mg I.V.) or bumetanide (1 mg) or torsemide 10 mg I.V. may be given to reduce the circulating blood volume and clear fluid overload by profuse diuresis. Fursemide, when given I.V. also exerts vasodilator action, thereby reduces venous return (preload).
3. To reduce afterload
• Vasodilators: Intravenous sodium nitroprusside 20-30 ug/min may be given to reduce afterload in patients whose systolic BP is above 100 mmHg.
• Nitrates: Nowadays, sublingual nitrate (0.4 mg every 5 min up to 3 tablets) is considered as first line therapy for acute cardiogenic pulmonary oedema, I.V. nitroglycerine (starting at 10 pg/min) can be given if patient is not in hypotension.
• ACE inhibitors: They reduce both preload and afterload, hence, are recommended in hypertensive patients with acute LVE.
• Natriuretic peptides: They also reduce afterload (vasodilator). Intravenous recombinant brain natriuretic peptide (nesiritide) is useful in cardiogenic pulmonary oedema. It is potent vasodilator with diuretic properties.
4. To improve ventricular contractility
• Digitalis: It is given to improve left
ventricular myocardial contractility,
hence, is useful in patients of LVF due
to systolic dysfunction. If the patient
has not taken digoxin within the last
5-6 days then 0.5 mg I.V. may be given
stat followed by 0.25 mg (half the initial dose) after 6 to 8 hours, if necessary, to a maximum of 1 mg/24 hours. This therapy is also beneficial if pulmonary edema has been precipitated by one of supraventricular tachyarrhythmia such as supraventricular tachycardia or atrial fibrillation with rapid ventricular rate.
5. If above measures fail, rotating tourniquets may be applied, but its efficacy is doubtful.
• Intra-aortic balloon counterpulsation: Intra-aortic balloon counterpulsation (IABP) is useful to relieve cardiogenic pulmonary oedema during cardiac surgical repair, e.g. acute mitral regurgitation, VSD.
6. To find out the underlying cause and to treat it: After instituting the above measures, attempt should be made to find out the precipitating factor such as an arrhythmia or infection which should be treated by appropriate anti-arrhythmic
and antibiotic therapy respectively.
7. For future management: The diagnosis of underlying disease must be established and if possible to be removed such as mitral valvotomy for MS, or surgical treatment for atrial myxoma, aneurysms or papillary muscle dysfunction.
• After discharge from the hospital,
patient should be advised salt restriction, avoid exertion; and the dose of a diuretic, digitalis and an ACE inhibitor should be properly adjusted to prevent further episode.