Hypotension And Hypertension Flashcards
What is the most common general cause of hypotension?
Loss of blood volume
What are the common ways in which hypotension can occur?
Blood loss due to: Haemorrhage Severe burns / sweating GI tract problems e.g. diarrhoea Unusual kidney losses
What are the other circumstances, other than blood loss, which can result in hypotension?
Allergic reactions
Emotional responses (possibly leading to fainting)
Decrease in cardiac contractility (due to heart attack)
How is hypertension defined?
A chronically increased systemic arterial blood pressure.
Between what values of bp is grade one hypertension?
140/90 - 159/99 mmHg
Between what values of bp is grade two hypertension?
160/100 - 179/109 mmHg
Between what values of bp is grade three hypertension?
Greater than 180/110 mmHg
What is the difference between primary and secondary hypertension?
Primary hypertension - no known cause though may be linked to genetic and environmental factors
Secondary hypertension - caused by another condition such as kidney damage, endocrine disorders, medications
What are the common treatments of hypertension?
ACE inhibitors
Angiotensin II receptor blocker
Beta blocker
Calcium channel blocker
Describe how the myogenic response maintains rate fo blood flow.
A rise in pressure in a vessel causes it to distend slightly so that the smooth muscle of the vessel wall is stretched - the muscle responds by contracting (this is the myogenic response), which narrows the vessels, increasing their resistance and restoring blood floe to its original value
How does the myogenic response work?
5e myogenic response to stretching depends on the activation of specific mechnorcepctor channels which increase the permeability of the membrane to sodium and potassium ions which leads to depolarisation and contraction of the smooth muscle of blood vessel walls
What is functional hyperaemia?
The phenomenon where the metabolic products of a cdll cause vasodilation - these products can be ATP,carbon dioxide and lactic acid for example
80% of patients have primary hypertension rather than secondary hypertension. T/F?
False - it is 90%
What are the risk factors for primary hypertension?
Obesity Increasing age Low level of fitness Moderate or high alcohol intake Metabolic syndromes Diabetes mellitus Black ancestry Poor diet
What are the possible causes of secondary hypertension?
Endocrine disorders such as cushings syndrome, conns syndrome and pharochromocytoma
Renal disease
Vascular pathology
What is the effect of chronic hypertension on the heart muscle?
The left ventricular wall hypertrophies
What are the possible chronic complications of hypertension?
Atherosclerosis Stroke MI Heart failure Renal failure Retinopathy
How do beta adrenoceptor blockers act as antihypertensives?
The block beta one sympathetic tone on the heart and reduce renin release from the kidney
This leads to a decrease in heart rate and stroke volume which decreases cardiac output and thus blood pressure
Give an example of a non selective beta adrenoceptor blocker
Propranolol
Give an example of a beta one elective beta adrenoceptor blocker
Atenolol
What are the possible side effects of beta adrenoceptor blockers?
Intolerance to exercise
Hypoglycaemia
Vivid dreams
Non selective drugs can exacerbate asthma
How do alpha adenoceptor blocks work as antihypertensives?
They decrease sympathetic gone in the arterioles by blocking alpha one receptors which decreases total peripheral resistance to decrease blood pressure
Give an example of a non selective alpha adrenoceptor blocker
Phentolamine
Give an example of an alpha one selective adrenoceptor blocker
Doxazosin
Prazosin
What are the adverse effects of alpha adrnoceptor blockers?
Postural hypotension
Loss of sympathetic vasoconstriction
Reflex tachycardia
How do ACE inhibitors work as antihypertensives?
They reduce the formation of the vasoconstrictor angiotensin II which decreases total peripheral resistance. It prevents an increase in blood volume by the loss of angiotensin II stimulated release of aldosterone and ADH
Give examples of ACE inhibitors
Captopril
Enalopril
ACE inhibitors have the adverse effect of a persistent irritant cough. How does this come about?
By the reduced breakdown of bradykinin which activates sensory nerves in the lung tissue
What type of angiotensin ii receptor mediates the vasoconstriction and aldosterone releasing reactions of angiotensin II?
AT1
Give examples of AT1 angiotensin II receptor blockers
Candesartan
Losartan
What is the advantage if using angiotensin II receptor blockers over ACE inhibitors?
They do not have the same persistent irritant cough side effect
Give an example of a diuretic used to treat hypertension
Benzoflumethiazide
How do diuretics act as antihypertensives?
The reduce renal reabsorption of sodium and water to decrease blood volume and therefore decrease blood pressure
What channels allow calcium entry into cardiac and smooth muscle?
L type voltage operated calcium channels
How do verapamil and diltiazem work to reduce blood pressure?
They bind to and block L type calcium channels on smooth muscle to decrease heart rate and decrease vasoconstriction
How does nifedipine work to reduce blood pressure?
It binds to an allosteric site of an L type calcium channel to prevent its action on smooth and cardiac muscle and decrease heart rate and vasoconstriction
Which calcium channel blocker is most effective on smooth muscle?
Nifedipine
Which calcium channel blocker is most effective on cardiac muscle?
Verapamil
Wh at are the adverse effects of calcium channel blockers?
Headaches
Constipation
Cardiac dysrhythmias
Which drug category should be used as first line treatment for hypertension for a white patient under 55?
ACE inhibitor or angiotensin II receptor blocker
Which drug category should be used as first line treatment for hypertension for a patient over 55 and/or of Caribbean or African descent?
Calcium channel blocker
