Heart Failure Pathophysiology

Question 1

what determines preload

Answer 1

venous return (EDV)

Question 2

main components determining afterload

Answer 2

vascular resistance

ventricular wall tension

Question 3

what is ionotropy

Answer 3

myocardial contractility

Question 4

what is ionotropy influenced by

Answer 4

NOT preload/afterload
Ca!!!
- L type channels (opened by cAMP)
- Na/Ca exchange (inhibited indirectly by cardiac glycosides)

Question 5

Ejection fraction in systolic vs diastolic HF

Answer 5

systolic: impaired contractility, dec EF <40%

Diastolic: normal EF, impaired diastolic ventricular relaxation and dec filling. –> dec SV and CO

Question 6

Name 3 conditions that lead to HF by:
damaging cardiac muscle:
increasing workload on heart:

Answer 6

cardiac muscle: IHD, cardiomyopathies, myocarditis

inc workload: hypertension, valvular disease, anaemia, thyrotoxicosis

Question 7

three types of cardiomyopathy

Answer 7

dilated (85%) - dilation in ventricle itself. no hypertrophy/thickening. impaired systolic function (change in actin/myosin).
= idiopathic, alcohol toxicity, viral myocarditis, peripartum

hypertrophic (10%) - proliferation of myoblasts put extra muscle down tends to affect IV septum. hypertension can cause.

Restrictive (5%)
- about changes in properties of wall. how it contracts/relaxes. eg. amyloidosis,

Question 8

four valvular abnormalities that cause L sided HF?

Answer 8

mitral stenosis (rheumatic fever)
mitral regurgitation (acute - no change in v wall. like MS. 
chronic - dilated myocardiopathy. chronic insid increase in EDV.)

aortic stenosis: degenerative calcification (can’t eject same amount, inc LV pressure, hypertrophy to try inc force)

aortic regurgitation

Question 9

four compensatory mechanisms to maintain cardiac output

Answer 9

sympathetic nerve activity
renin-angiotensin-aldosterone
Frank-starling
fluid movements

Question 10

problem with frank starling in HF

Answer 10

inc vasc volume causes inc EDV

increases muscle stretch and O2 consumption

Question 11

problem with sympathetic activity in HF

Answer 11

causes tachy, vasoconstriction, dec perfusion of tissue, renin release etc.
this all increases workload of heart.

Question 12

problems with RAAS in HF

Answer 12

angiotenisin: vascocontrictor, aldosterone releae

increase Na and water reabsorption AND inflammatory responses depositing collagen in ventricles = stiffer