Heart Failure Flashcards
Primary Cause of Heart Failure
Decreased cardiac output
Decreased Heart Rate
Decreased Force of Contraction of Heart
and Decreased Volume of Blood in Heart which decreases volume of blood ejected from the heart with each heart beat
Types of Heart Failure
Acute Heart Failure
-develops rapidly (hours/
- life threatening
- successful management by pharmacological or surgical interventions
Chronic Heart Failure
- long term condition (months/
- associated with adaptive changes in the heart
Compensatory Mechanisms to Restore Cardiac Output
In Chronic Heart Failure
Increased Sympathetic Activity
- increased heart rate
- increased force of contraction
Increased Renin Angiotensin Aldosterone System
lead to retention of water and salt ( in kidney lead to increased volume of blood returning to the heart
both lead to constriction of blood vessel
increased arterial blood pressure
increased resistance to blood flow
decreased cardiac output !
Characteristics of Chronic Heart Failure
Increased Sympathetic Activity -lead to heart rate and force of contraction of heart \+ constriction of blood vessels which lead to increased cardiac workload then lead to myocardial hypertrophy
Increased Renin Angiotensin Aldosterone System
lead to increased water and salt retention + constriction of blood vessels
which lead to
- myocardial hypertrophy
-oedema of peripheral tissues
eg swelling of legs and ankles
fluid in lungs increased shortness of breath)
Type and effect of Positive Inotropic Drugs
Positive Inotropic Drugs
- Force of Contraction of the Heart
-Cardiac Glycosides
eg digoxin
-b-Adrenoceptor Stimulants
e g dobutamine, dopamine
-Phosphodiesterase Inhibitors
e g amrinone milrinone
which three of them increased intracellular calcium concentration
-Calcium Sensitizer e g levosimendan
Name of Cardiac Glycosides and mechanism of actions
e.g. digoxin
Inhibit Na ++/K ATPase (sodium pump)
-which increased intracellular sodium concentration
- which lead to decreased Ca2 expulsion by Na +/Ca2+ exchanger
- then lead to increased intracellular calcium concentration
-facilitate parasympathetic activation
Characteristics of Digoxin
Advantages
-Anti-Arrhythmic drug
Adverse Effects Pro-Arrhythmic GI Disturbances CNS Disturbances Narrow Safety Margin
Applications NOT 1st Line Therapy Effect Opposed by increased K Effect Opposed by increased Mg 2+
Name and mechanism of actions β-Adrenoceptor Stimulants
e.g. dobutamine , dopamine
Activate b1-Adrenoceptor in the Heart
lead to the increased intracellular concentration of cyclic adenosine monophosphate (cAMP)
then lead to activate protein kinase A (PKA)
-which lead to increased calcium entry in cardiac cells
-then lead to increased intracellular calcium concentration
Characteristics of
β Adrenoceptor Stimulants
Advantages
- Fast Onset
- Short Duration of Action
Adverse Effects
- Tachyphylaxis
- Pro-Arrhythmic
- Pro-Angina
Applications
Used For
Acute Heart Failure
Names and mechanism of actions of Phosphodiesterase Inhibitors
e.g. inamrinone , milrinone
- decreased breakdown of cAMP
- which lead to increased PKA activation
- then lead to increased intracellular calcium concentration
Characteristics of Phosphodiesterase Inhibitors
Advantages
-Vasodilator Action
Adverse Effects
- GI Disturbances
- Pro-Arrhythmic
Applications
-Used For Acute Heart Failure
Choices of Positive Inotropic Drugs (Common properties)
All three has Pro-arrhythmic effects
B-adrenergic receptor stimulants and phosphodiesterase inhibitors are used for acute heart failure
Name and mechanism of actions of Calcium Sensitizers
e.g. levosimendan
Stabilize the Binding between Troponin C and Calcium
- increased the affinity of troponin C for calcium
increased sensitivity to calcium contractility WITHOUT increasing intracellular calcium concentration
Characteristics of
Levosimendan
Advantages
-Coronary and
systemic vasodilator
Available Formulations
-Intravenous
Adverse Effects
Headache
Hypotension
Name, Effect and Adverse efffect Inhibitors of
Renin
Angiotensin System
Inhibitors of
Renin Angiotensin System
Angiotensin Converting Enzyme Inhibitors
-eg captopril enalapril quinapril
Angiotensin Receptor Blockers eg losartan
Pharmacological Effects
- reduces fluid retention
lead to decreased blood volume (slightly diuretic)
which reduces oedema
- reduces vasoconstriction
which lowers peripheral vascular resistance
and then decreased cardiac workload
Adverse Effects
severe hypotension (e g in patients with fluid loss)
hyperkalemia therefore caution with K sparing diuretics