Pathophysiology of CHF PABITRAAAAAAAAppt

CHF

1. Congestive Heart Failure
Pabitra Subedi
Pathophysiology CIST-BPharm 2024

2. What is Heart Failure
•Resultsfromanystructuralorfunctionalabnormalitythat
impairstheabilityoftheventricletoejectblood(Systolic
HeartFailure)ortofillwithblood(DiastolicHeartFailure).

3. Compensatory responses during heart failure
Heart failure
↓ FOC ↓ CO ↑ Sympathetic
discharge
↓ Renal perfusion
•Vasoconstriction
•β1 activation
↑ preload
↑ afterload
↑ FOC
↑ HR
↑ Renin
release
↓ GFR
Cardiac
remodelling
Ventricular
dilation
Back pressure
Oedema
Na &
water
retention
(Oedema)
↑ AT-II
↑ AT-1
↑ Aldosterone
Initially ↑CO
Later ↓ CO

4. Pathophysiology of CHF
•Pump fails → decreased stroke volume /CO.
•Compensatory mechanisms kick in to increase CO
–SNS stimulation → release of epinephrine/nor-epinephrine
•Increase HR
•Increase contractility
•Peripheral vasoconstriction (increases after load)
–Myocardial hypertrophy: walls of heart thicken to provide more muscle
mass → stronger contractions

5. Pathophysiology of CHF
•Hormonalresponse:↓renalperfusioninterpretedbyjuxtaglomerularapparatus
ashypovolemia.
•Thus:
–Kidneysreleaserenin,whichstimulatesconversionofantiotensinI→
angiotensinII,whichcauses:
•Aldosteronerelease→Na+retentionandwaterretention(viaADH
secretion)
•Peripheralvasoconstriction
•CompensatorymechanismsmayrestoreCOtonear-normal.
•But,ifexcessivethecompensatorymechanismscanworsenheartfailure

6. Pathophysiology of CHF
•Vasoconstriction:↑’stheresistanceagainstwhichhearthastopump(i.e.,
↑’safterload),andmaytherefore↓CO
•Naandwaterretention:↑’sfluidvolume,which↑’spreload.Iftoo
much“stretch”→↓strengthofcontractionand↓’sCO
•Excessivetachycardia→↓’ddiastolicfillingtime→↓’dventricular
filling→↓’dStrokeVolumeandCO
Pathophysiology CIST-BPharm 2024

7. The Vicious Cycle of Congestive Heart Failure
Decreased Blood Pressure and
Decreased Renal perfusion
Stimulates the Release
of renin, Which allows
conversion of
Angiotensin
to Angiotensin II.
Angiotensin II stimulates
Aldosteronesecretion which
causes retention of
Na+ and Water,
increasing filling pressure
LV Dysfunction causes
Decreased cardiac output

8. Congestive Heart Failure

9. Types of Heart Failure
•Low-Output Heart Failure
–Systolic Heart Failure:
–decreased cardiac output
–Decreased Left ventricular ejection fraction
–Diastolic Heart Failure:
–Elevated Left and Right ventricular end-diastolic pressures
–May have normal LVEF
•High-Output Heart Failure
–Seen with peripheral shunting, low-systemic vascular resistance, hyperthryoidism, beri-
beri, carcinoid, anemia
–Often have normal cardiac output
•Right-Ventricular Failure
–Seen with pulmonary hypertension, large RV infarctions.
Pathophysiology CIST-BPharm 2024

10. Left and right sided HF
Left sided HF
•Results from LV dysfunction
•Blood backs up into left
atrium
•Pulmonary congestion and
edema
Right sided HF
•Results from diseased right
ventricle
•Blood backs up into right
atrium and venous circulation
Pathophysiology CIST-BPharm 2024

11. Left-sided HF

12. Right sided heart failure
Pathophysiology CIST-BPharm 2024

13. Causes of Low-Output Heart Failure
•Systolic Dysfunction
–Coronary Artery Disease
–Idiopathic dilated cardiomyopathy (DCM)
•50% idiopathic (at least 25% familial)
•9 % mycoarditis (viral)
•Ischemic heart disease, perpartum, hypertension, HIV, connective tissue disease,
substance abuse, doxorubicin
–Hypertension
–Valvular Heart Disease
•Diastolic Dysfunction
•Hypertension
•Coronary artery disease
•Hypertrophic obstructive cardiomyopathy (HCM)
•Restrictive cardiomyopathy

14. Symptoms of HF

15. Clinical Presentation of Heart Failure
•Due to excess fluid accumulation:
–Dyspnea (most sensitive symptom)
–Edema
–Hepatic congestion
–Ascites
–Orthopnea, Paroxysmal Nocturnal Dyspnea (PND)
•Due to reduction in cardiac ouput:
–Fatigue (especially with exertion)
–Weakness

16. Epidemiology
•The lifetime risk of developing HF is 20% for Americans >40 years of age
•More than 800,000 new HF cases are diagnosed annually in US
•Incidence increases with age, rising from approximately 20 per 1000 individuals 65
to 69 years of age to >85 years
•Mortality rates for HF remain approximately 50% within 5 years of diagnosis
•The total cost of HF care in the US exceeds more than 35bn annually, with over half
of these costs spent on hospitalization

17. Major risk factors
•CAD
•Age
•HTN
•Obesity
•Smoking
•DM
•Dyslipidimia