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Drugs that decrease afterload and preload of the heart

ACE Inhibitors and Angiotensin Receptor Blockers Beta blockers CCBs Nitrates Diuretics
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RAAS =
Renin Angiotensin Aldosterone System
What does RAAS do?
A hormone system that regulates blood pressure and water (fluid) balance.
When blood volume is low, juxtaglomerular cells in the kidneys secrete renin directly into circulation. Plasma renin then carries out the conversion of angiotensinogen released by the liver to angiotensin I. Angiotensin I is subsequently converted to angiotensin II by ACE found in the lungs. Angiotensin II is a potent vaso-active peptide that causes blood vessels to constrict, resulting in increased blood pressure. Angiotensin II also stimulates the secretion of the hormone aldosterone from the adrenal cortex. Aldosterone causes the tubules of the kidneys to increase the reabsorption of sodium and water into the blood. This increases the volume of fluid in the body, which also increases blood pressure.
Action of renin
Proteolytic enzyme, converts angiotensinogen to angiotensin 1 ( inactive)
ACE
Angiotensin Converting Enzyme
(A1 to AII)
ACE degrades ...
Bradykinin (potent vasodilator, lowers BP)
Angiotensin I
Inactive, formed from angiotensinogen by ACE
Angiotensin II
Active, formed from angiotensin I by ACE
Angiotensin II action
Causes systemic vasconstriction to push the blood to vital organs and secretes aldosterone (causes sodium and water retention),
ACE Inhibitors
Blocks ACE enzyme,also blocks angiotensin II and bradykinin. Lowers blood pressure.
Avoid with: potassium-sparing diuretics, BP lowering meds, any drug that raises potassium (hyperkalemia)
Side effects: "Ace" cough, hyperkalemia, tetrogenesis, angioedema, 1st dose hypertension
The 'pril' drugs (enalapril, captopril)
ARBs
Angiotensin Receptor Blockers. These lower blood pressure. Blocks angiotensin II access to receptors on blood vessels- not affect bradykinin!!!
Avoid with: ACEi's (choose a class!), with another hypotension drug
Side effects: tetrogenesis, angioedema (very rare with this drug!)
**This is tetrogenic
The 'sartans' (Losartan, Candesartan)
Theoretical ARB benefits over ACEs:
Less drug interactions, less adverse effects, doesn't cause bradykinin accumulation.
This is a very well-tolerated drug.
Classes of drugs reduce cardiac AFTERLOAD (resistance)
Beta 1 adrenergic blockers
Calcium channel blockers (CCB's)
Vasodilators
Afterload
The RESISTANCE a muscle overcomes to contract in the aorta
Beta 1 blockers
Blocks cardiac beta receptors
Reduces: contractility, HR, CO, SV
This drugs slows the heart down so that it can rest.
Avoid with: beta inhaler, Non-dihydropyridines (CCB), insulin (hypoglycemia)
Side effects: bradycardia, broncochonstriction, blocks glyconeogenesis, fatigue, tired, depression from decreased cardiac output, Diabetecs should try and avoid this drug
Suffix "-olol" (Metroprolol)
Selective beta blockers
Block only beta-1 (cardiac)
Non-Selective beta blockers
Block all betas (heart and lungs)
Dihydropyridines (CCB)
Works on vascular smooth muscle
Side effects: Reflex tachycardia, flushing, dizziness, headache, edema
** This works well with Beta blockers (to control the tachycardia)
Drug name: suffix "-dipine" (Amlodipine)
Non-dihydropyridines (CCB)
Works on vascular smooth muscle and the heart
Side effects: Bradycardia, flushing, dizziness, headache, edema
*Do NOT use with Beta blockers, and do NOT use with digoxin (toxicity increased)
Drug name: Verapamil, diltiazam, Cardizem
Nitrate (Nitroglycerin)
Systemic vasodilator, mainly works on veins, but do impact the arteries. Decreases BOTH afterload and preload. Decreases demand and workload but does NOT decrease O2 demand or blood volume.
Avoid with: Phosphidiasterase 5 inhibitors (viagra/cialis)
Good with: CCB's and Beta blockers
Side effects: Reflex tachycardia (beta blocker helps this), edema (diuretic), orthostatic hypotension, headache, tolerance, hypertrichosis
RAAS inhibiting drugs
1) ACEi- Blocks ACE enzyme
2) ARB's- blocks Angiotension II
access to receptors
Class of drugs to decrease cardiac PRELOAD
Nitrates
Diuretics (3 kinds)
Preload
The amount of STRETCH or tension applied to a muscle prior to contraction
High ceiling diuretics
Block sodium reabsorption in the ascending loop of Henle. Reduces edema and fluid overload, decreases BOTH preload and afterload, kidney disease
Avoid with: other BP lowering meds, other ototoxic meds,
Do not use with Digoxin!!!
Good with: Potassium sparing diuretics
Side effects: dehydration, hypotension, ototoxicity, hyponatremia, hypokalemia, hyperuricemia
** Not known to be tetrogenic
Drug name: Furosemide
Thiazide
Blocks sodium chloride reabsorption in the distal convoluted tubule. Reduces edema and hypertension.
Avoid with: other BP lowering meds, pregnancy and breastfeeding, Do not use with Digoxin!!!
Good with: Potassium sparing diuretics
Side effects: tetrogenesis, hyponatremia, hypokalemia, hyperuricemia
**This is tetrogenic
**Not ototoxic, well tolerated
Spironolactone (Potassium sparing diuretic)
Blocks aldosterone in the distal nephron, sodium and water loss without losing potassium
Avoid with: ACEi's (also raises potassium)
Good with: other diuretics
Side effects: Hyperkalemia (too high)
This drug gets combined with other diuretics (high ceiling and thiazide) to prevent potassium loss
Drug name: Aldactone
Triamterene (Potassium sparing diuretic)
Disrupts potassim/sodium exchange in the distal nephron, sodium and water loss without losing potassium
Avoid with: ACEi's (also raises potassium)
Good with: other diuretics
Side effects: Hyperkalemia (too high), leg cramps
This drug gets combined with other diuretics (thiazide) to prevent potassium loss
Physiological regulators of blood
pressure
1) Sympathetic nervous system
2) RAAS
3) Kidneys
Cardiac output
Amount of blood expelled by the ventricles of the heart per minute, determined by heart rate, contractility, blood volume, and venous return, 5L per minute (healthy)
CO = HR x SV
Stroke volume (SV)
Amount of blood expelled in one heartbeat
Myocardial contractility
How well the muscle is working (force)
Blood pressure
Cardiac output x Peripheral resistance
Peripheral resistance
Resistance against vasculature
Determined by arteriolar constriction
The relationship of afterload (AF) and stroke volume
Indirect relationship
ex:
high AF (resistance) = low SV (blood from one heartbeat) (has to work harder against more resistance to pump)
low AF (resistance) = high SV (blood from one heartbeat)
"DOOR OPENING AGAINST SOMEBODY ON OUTSIDE"
The relationship of preload (PL) and stroke volume
Direct relationship
ex:
high PL (stretch)= high SV (blood from one heartbeat)
Cardiac remodeling
Cardiacs response to injury is changing in size and shape, heart becomes stretched out and loses some function
Aldosterone
A steroid hormone whose overall effect is to increase reabsorption of ions and water in the kidney -- increasing blood volume and, therefore, increasing blood pressure.
Angioedema
Swelling of the dermis under the skin, capillaries leak, tongue swells, can be fatal
Hyperkalemia
A medical emergency due to the risk of potentially fatal abnormal heart rhythms (arrhythmia).
Hyponatremia
a metabolic condition in which there is not enough sodium (salt) in the body fluids outside the cells
Hyperuricemia (Gout)
a kind of arthritis that occurs when uric acid builds up in blood and causes joint inflammation