Hypertension Flashcards
When is flow to the systemic organs the highest
During systole (when the pressure reaches 120 mm Hg), except for the left ventricle
What is the definition of hypertension
Diastolic pressure more than 90 and systoic pressure more than 140
3 different causes of hypertension
An increase in CO, or TPR or both
2 types of hypertension
Primary hypertx: underlying cause is unknown, happens 95% of the cases
Secondary hypertx: the cause of increase in CO or TPR can be identified
What do the cardiac glycosides do
They block Na-K ATPase, this causes Na to be very high inside the cell activating Ca-Na pump which increases Ca levels inside the cell, increasing the inotropic state of the heart
What are the 2 possible reasons for primary hypertension
- Abnormal function of Na-K pump, this causes increase in Ca intracellular levels
- Microvascular dysfunction: decreased levels of NO and increased levels of endothealin 1
There’s evidence that some people have elevated levels of ouabain which causes hypertension since ouabain is a cardiac glycoside
Trend of role of CO and TPR in hypertension with age
How does TPR increases with age
There are 2 major mechanisms:
- Arteriolar hypertrophy in response to high blood pressure results and this causes the lumen of the arterioles to decrease
- Compliance of the ventricles decreases which impairs dyastolic filling, an increase in inotropic state is hence required
What are the different forms of secondary hypertensions
- Renal parechymal disease
- Renovascular disease
- Pheochromocytoma
- Hypothyroidism
- Hyperthyroidism
Renal Parenchymal disease
Damage to the kidneys results in higher retention of Na and water.
What physical can you look for to check for renal parechymal disease
JVD
Renovascular hypertension
There is more renin released in this disease
What receptor stimulation causes renin secretion
Beta 1 stimulation
Pheochromocytoma
It is important to know that there is an increase in CO and TPR both
What happens to baroreflex in chronic hypertension
It adapts to the high blood pressure, this is called baroreceptor desensitivity. Curve shifts to the right, the rate of firing occurs at a higher arterial pressure. This means they will be opposing the effect drugs to treat this hypersensitivity.
Eventually the baroreceptor sensitivity recovers with drug treatment
Conn’s Syndrome
There is an adrenal gland syndrome.
This also causes increase K secretion which causes hypokalemia.
Summary of hypertension
Effects of hypertension
How do you differentiate between diastolic and systolic function
Ejection fraction
It is important to know why this is the case
In systolic the heart cant beat strong enough and in diastolic the heart has reduced compliance so it doesnt fill far enough
Effects of phenylephrine
How do you differentiate if isoproterenol is stimulating beta 1 or beta 2 receptors?
They key is to look at the MAP first, Beta 1 causes an increase in MAP while beta 2 causes a decrease in MAP
