KNOW ABOUT HEART FAILURE
7 May 2021
What is Heart Failure?
It is a chronic condition where our heart muscle is unable to pump blood to meet the body’s need for blood and oxygen.
What causes Heart Failure?
It may be due to
HYPERTENSION: High blood pressure,
CORONARY ARTERY DISEASE: Buildup of plaque that narrows coronary arteries leads to decreased blood flow to the heart.
HEART ATTACK: When the artery supplying blood and oxygen to heart is blocked.
CARDIOMYOPATHY: Enlargement of heart muscle.
MYOCARDIAL INFARCTION: Reduced blood flow in coronary artery due to atherosclerosis and occlusion of artery by an embolus or thrombus.
What happens in the body due to Heart Failure? ( Figure 1)
In kidney (α1) constriction occurs at smooth muscles of acute renal arterioles that decreases blood flow to the kidney.
It results in decreased GFR, causing less urine outflow and increases fluid retention.
Due to increase in fluid retention there will be an increase in venous return causing an increase in PRELOAD, leading to increased stroke volume and further increases CARDIAC OUTPUT.
The sympathetic nervous system also stimulates fibres in JG cells and releases RENIN , it moves to the liver and gets converted into ANGIOTENSIN-I.
Through venous blood the ANGIOTENSIN-I enters the right atrium then to lungs, where it gets converted into ANGIOTENSIN-II in presence of Angiotensin converting enzyme.
This ANGIOTENSIN-II moves to posterior pituitary gland that releases ADH causing increase in water reabsorption that leads to increase in blood volume --> increase in venous return --> Increase in preload causing increase in stroke volume and finally increases CARDIAC OUTPUT.
The ANGIOTENSIN-II also act on zona glomerulous of adrenal gland causing secretion of ALDOSTERONE that acts on kidneys for reabsorption of sodium and water into blood causing increase in blood volume and increasing CARDIAC OUTPUT.
Heart failure depends on CARDIAC OUTPUT.
Cardiac output = Heart rate × Stroke volume
So an increase in Heart rate or Stroke volume causes an increase in cardiac output.
But activating all these systems can further increase workload on HEART. So treatment should be started immediately after identifying the symptoms of HEART FAILURE.
From the above information we can clearly understand what kind of treatment can be given.
Diuretics : To decrease fluid retention in the body
Vasodilators : For preventing vasoconstriction of the blood vessels
ACE inhibitors: To inhibit conversion of Angiotensin I into Angiotensin II , the Angiotensin converting enzyme is blocked.
Beta Blockers : To act on Beta receptors
Aldosterone Antagonist: To antagonize / decrease the function of Aldosterone.
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