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Flashcards in Heart Deck (15):
1

Normal sinus rhythm

characterised by depol from SA node, atria, AV node, Bundle of his, purkinje fibres (ventricles)

2

Heart failure Definition

Condition in which the cardiac output is insufficient to meet the metabolic demands of the body

3

Syncope

passing out, short loss of consciousness and muscle strength

4

ANP

atial natiuretic peptide- potent vasodilator, It is released by muscle cells in the upper chambers (atria) of the heart (atrial myocytes) in response to high blood volume. ANP acts to reduce the water, sodium and adipose loads on the circulatory system, thereby reducing blood pressure.[1] ANP has exactly the opposite function of the aldosterone secreted by the zona glomerulosa in regard to its effect on sodium in the kidney – that is, aldosterone stimulates sodium retention and ANP generates sodium loss.[4][5]

5

Congestive heart failure- Goal: increase CO

- by decreasing fluid overload(preload) with diuretics- furosemide in ascending loop of henle, and spironolactone in distal tubule
or- decreasing bp - by either decreasing heart rate (beta blockers- carvedilol, atenolol)
or increasing vasodilation with ACE- inhibitors (Ramipril) which block the production of angiotensin 2 which acts as a vasoconstrictor, also angiotensin regulates aldosterone- so reducing angiotensin 2 causes a reduction in aldosterone which leads to a reduced sodium and water reabsorption from urine - therefore also reduces fluid overload (blood vol)
increasing vasodilation- also with Ca antagonists - nifedipine
- increase force- with PDE inhibitors- prolong Ca influx (milrinone, caffeine)

6

ERP

during the effective refractory period (0-3) a new AP cannot be regenerated, limits increase in heart rate.
used by some antiarrythmic drugs- like amiodarone, class 3 , decreases K+ conductance and therefore prolongs phase 3 , effective in abolishing reentry currents

7

Blood pressure should be below

120/80 (most adults between 120/80- 140/90 mmHg) first number- systolic bp (when ventricles contract, highest bp) , second number is the diastolic bp (when filling of ventricles occurs)
1/ 5 people have this

8

disease of high blood pressure

is characterized by an increased peripheral resistance - the level of vascular smooth muscle tone is dependent on alpha1 adrenoceptor mediated sympathetic tone
Bp= CO x total peripheral resistance

9

pheochromocytoma, shushing syndrome, bright disease

can be causes of hypertension. pheo- too much adrenal medulla hormone secretion, cushing syndrome- too much cortisol, bright syndrome- kidney disease

10

diazoxide, minoxidil

blocks the action of ATP on atp-sensitive K+ channels (ATP blocks them), therefore K+ channels remain open, hyperpolarisation and closure of L-type Ca++ channels- causes vasodilation
in cardiac and scmooth muscle and pancreatic islet- insulin secreting cells

11

Nifedipine works on vessels more than heart

Ca channel blocker, relaxation

12

diaxozide uses

used in emergenxy hypertension, causes hyperglycaemia

13

minoxidil

used in severe hypertension and unresponsive to other drugs, very potent and long acting, also causes hypertrichosis- can be used to treat baldness

14

Hydralazine

causes atriolar vasodilation, unknown mech of action, co-administered with beta blocker to block baroceptor reflex

15

Nitrovasodilators

pretty short acting, minute to minute control