Inotropic Agents. Flashcards
What is an Inotrope?
It increases or decreases action of the heart (rate, force). (+ve Inotrope increases action USED TO TREAT HEART FAILURE).
Chronic heart failure life expectancy.
50% die in 6 months, 50% die within 5 years (mild-moderate).
Compensatory mechanism of heart failure.
Reduced cardiac output causes the kidneys to release renin. Renin leads to the release of Angiotensin 2 which cause vasoconstriction and the production of Adolsterone. Vasoconstriction increases afterload whereas Adolsterone cause water retention leading to increase in preload. These two actions can cel each other out but cardiac failure also causes SNS activation which increases heart rate and force. This along with the increased preload attempts to increase cardiac output. The heart will also increase in size to increase cardiac output.
Describe the signs and symptoms of heart failure.
Breathlessness, Tiredness, Palpitations, Orthopnea, Confusion, (Nocturia, Pedal Oedema - due to water retention).
What would a chest X-ray show in a patient with heart failure?
An enlarged heart.
What is the principle behind the treatment of acute heart failure.
Symptomatic relief.
What are the principles behind treatment of chronic heart failure?
Symptomatic relief, Better hemodynamics, Better mortailty.
Drugs given in the management of heart failure?
Diuretics, ACE-inhibitors, ARB (in patients sensitive to ACE inhibitors), Betablockers, Vasodilators, Postivie Ionotroped (digoxin).
Name some ACE inhibitors.
PRIL - ENalapril, Captopril, ramipril.
Side effects of ACE inhibitors?
Cough and Increased Potassium.
Name some ARB’s?
Losartan, Irbesatan, Candesartan.
What do Diuretics do?
Increase water and sodium excretion.
How do DIuretics works?
THey work by decreasing the reabsorption of Na= and Cl- from kidney filtrate. Fluid loss can decrease edema, and preload.
Side effects of diuretics?
Toxicity as some stuff won’t be excreted right, Electrolyte imbalance.
TPR?
Total Peripheral Resistance?
What are diuretics commonly used with?
ACE inhibitors (have the same outcome).
Method of action of Adolsterone antagonists?
Increase salt and water excretion. (Adolsterone causes water and sodium retention).
Name some beta blockers used in heart failure management.
LOLS, Carvedilol, Bisoprolol, Metoprolol.
Why should caution be exercise when beta blockers are used for cardiac failure treatment?
They can have negative Inotropic effects.
How can beta blockers be beneficial in the treatment of heart failure?
Decreases heart rate and force, thereby increasing filling time and ejection volume,
Reduces sympathetic outflow from the brainstem, thereby reducing cardiac remodelling (reduces cardiac contractility),
Reduces Renin, angiotensin and adolsterone causing decrease in preload and afterload,
Reduce hypertension and arrhytmias.
Adverse effects of Beta blockers.
Bronchoconstriction, Diabetes, Disturbances in lipid metabolism.
How would vasodilators help in the management of heart failure?
Decrease preload and afterload.
Name an ateriolar dialator.
Hydralazine.
Name a venodialator.
Isosorbide dinitrate.
Non-selective vasodilators.
Nitroprusside.
Name some Positive Inotropes.
Digoxin, B1 agonists - Dobutamine, Bipyridines, Dopamine, Levosimendan.
Digoxin.
A positive Ionotrope. Increase force of contraction.
How does Digoxin work?
Inhibit Na+/K+ ATPase causing increased intracellular calcium leading to increased myocardial contractility.
Adverse effects of Digoxin?
Arrythmia, Nausea and vomiting, Visual disturbances.
Narrow safety margin as antibodies made to overdose.
How does Dobutamin work?
B1 selective agonist which increases cAMP synthesis and inward Calcium influx. Stimulates myocardial contractility.
How would Bipyrdines work?
They are postive ionotropic agents with vasodilator activity. They can also inhibit PDE which normally degrades cAMP. Increased cAMP increases inward calcium influx and heart contractility.
