Hypertension and HF Flashcards
Name two ACE inhibitors
Lisinopril
Ramipril
What is the mechanism of action of ACEi?
- Blocks AngII and therefore, lack of vasoconstriction of the EA. GFR not maintained and decreases.
- Lack of ADH production so less water reabsorbed.
- Lack of aldosterone production so less K+ secreted and less Na+ reabsorbed at the collecting ducts.
- decreased sympathetic output = decreased chronotropy and inotropy of heart. Decreased renin release.
Common side effects of ACEi
- ACE inhibited therefore bradykinin is not broken down into peptide fragments: dry cough and angioedema (bradykinin is a vasodilator so increased hydrostatic pressure)
- Renal failure as GFR low and cannot be maintained
- Hypotension from vasodilation
Avoid the use of ACEi in:
- Renal artery stenosis (GFR is already decreased)
- AKD (decreased perfusion)
- Pregnancy and breastfeeding (ACEi are teratogenic)
Drugs to avoid with ACEi
- K+ sparing diuretics = hyperkalaemia and bradycardia/ asystole.
- NSAIDs = block prostaglandins resulting in vasoconstriction of AA so decreased GFR. Extreme GFR decrease leads to decreased perfusion and pre-renal AKD.
In which patients is ACEi used as first line treatment?
- Hypertension with type II diabetes
- Hypertension without type II diabetes and is < 55 yrs old and not of African descent.
What added benefit does ACEi provide in those with type II diabetes?
- Two pronged approach. ACEi causes vasodilation of the EA and also decreases BP resulting in a reduced intraglomerular pressure which is good for patients with type II diabetes as it can cause nephrotic syndrome (diabetic nephropathy) and CKD with proteinuria.
Name two AngII receptor blockers
Losartan
Candesartan
What is the mechanism of action of ARBs?
- Block AT1 receptor (has vasoconstrictive effects).
- Lack of vasoconstriction of VSM, heart and kidney.
- Same effects are ACEi.
Are the side effects caused by presence of bradykinin experienced?
No. ACE is not being affected and so bradykinin will be broken down into its peptide fragments. No dry cough or angioedema.
Drugs to avoid when using ARBs: contraindications
- K+ sparing diuretics
- NSAIDs
Avoid ARB usage in:
- Renal failure patients - AKD
- Renal artery stenosis
- Pregnancy
- Breastfeeding
Name drugs in the CCB class
- Divided into two classes:
- Dihydropyridines: amlodipine, nimodipine, nifedipine
- Non-dihydropyridines: phenylalkylamines (Verapamil), benzothiazapines (diltiazem)
Mechanism of action of dihydropyridines.
- Acts in peripheral vasculature and causes vasodilation.
- Decreased TPR and so CO increases to counteract this - patient becomes tachycardic.
Side effects of dihydropyridines
- Ankle swelling
- Palpitations (from compensatory tachycardia)
- Flushing
- Headaches
Avoid CCBs Dihydropyridines in patients with:
- Unstable angina due to risk of arrhythmia; patient is already tachycardic.
- Severe aortic stenosis - CO is already decreased so decreased BP - exacerbated by CCBs = hypotension risk.
Contraindications of CCBs:
- Amlodipine is metabolised by CYP3A4 and this is inhibited by Statins. Avoid statins.
- Avoid other antihypertensive drugs (ACEi, BB, ARBs etc)
For which patients is CCB used as a first line treatment?
- Hypertension without type II diabetes in patients > 55 yrs and those of African Caribbean descent (have low renin levels naturally).
Mechanism of action of phenylalkylamines.
- Act on the myocardium causing decreased SAN and AVN conduction. Therefore, AV conduction decreases and you have negative chronotropy and inotropy of the heart.
- Prolonged AP and effective refractory period.
- Used for SVT rate control.
Mechanism of action of benzothiazapines
- Acts on both peripheral vasculature and myocardium
Contraindications of non-dihydropyridines CCBs :
- Beta blockers = also causes a decreased chronotropy and inotropy increasing risk of asystole.
What are the main diuretics used in hypertension?
- Thiazides or thiazide like diuretics
Mechanism of action of Thiazides
- Acts on the DCT and blocks NCCT (sodium-chloride co-transporter). Decreases sodium reabsorption from the lumen so intracellular [Na] is low. This causes up-regulation of the Na+/Ca2+ channel on the basolateral membrane so increased Ca2+ reabsorption occurs.
- Increases uric acid reabsorption.
- ENAC unregulated at the DCT distally and collecting duct so more K+ removed from blood.
Side effects of thiazides:
- Hypokalaemia = VF and arrhythmia risk
- Hyponatraemia
- Hyperuricaemia = Gout
- Hypercalcaemia
Contraindications of thiazide diuretics:
- NSAIDs = both are nephrotoxic
- Hypokalaemic drugs
Name drugs in Beta Blocker class.
- Metoprolol
- Bisoprolol
- Labetalol
Mechanism of action of Beta blockers
- blocks the B1 receptor at the SAN.
- Decreases slope of pacemaker potential in SAN. Decreased AV conduction so decreased supraventricular tachycardia.
- Decreased chronotropy and inotropic effect - low HR and BP.
Contraindications of BB:
- Non-dihydropyridines CCBs as they also cause decreased chronotropy and inotropy of the heart, as well as SAN conduction to decrease.
- Risk of asystole.
At what stage are beta blockers used as part of treatment for hypertension in both emergency and non-emergency situations?
- Emergency IV antihypertensive
- Step 4 hypertension is resistant hypertension - treat using spironolactone, alpha and beta blockers.
Name a drug in the alpha blocker class
- Doxazosin
Mechanism of action of alpha blockers
- Decreases TPR as it blocks alpha 1 receptor in the peripheral vasculature, causing vasodilation.
- Used as treatment in BPH by relaxing smooth muscle of prostate and decreasing pressure on prostatic urethra, allowing urine to pass.
In which patients should you avoid using AB:
- Postural hypotensive patients
Contraindications of alpha blockers:
- Dihydropyridines as they cause vasodilation of peripheral vasculature too = excessive hypotension risk.
- Risk of oedema with these drugs too
What are the four treatments for heart failure?
1) Diuretics such as furosemide = for SYMPTOM RELIEF ONLY
2) ACEi
3) BB
4) ARBs if intolerant to ACEi.
What effect do the ACEi, BB and ARBs have on treating heart failure?
- They decreases the preload and afterload, treating the natural body’s neurohormonal pathway that exacerbates HF.
What is the treatment for MI?
- Aspirin
- ACEi
- BB
- Statins
