CARDIO1 - PATHOPHYSIOLOGY OF HEART FAILURE

Question 1

causes of heart failure

Answer 1

• hypertension
• valvular disease
• coronary artery disease
• idiopathic cardiomyopathy
• congenital heart disease
• metabolic/endocrine
• infective

Question 2

precipitating factors of heart failure

Answer 2

1. INCREASED CARDIAC OUTPUT: infection, pregnancy, anemia and hyperthyroidism
2. CARDIOVASCULAR EVENTS: arrhythmia, myocardial ischemia
3. CONCOMITANT MEDICATION:
   - sodium retention: NSAIDS, Steroids
   - negative inotropes
   -antiarrythmic drugs - calcium channel blockers
   alcohol
   trycyclic antidepressants
4. NON COMPLIANCE:
   - Diet - increased sodium
   - excesssive fluid intake
   - missed medication

Question 3

compensatory mechanisms? - sympathetic nervous system

Answer 3

• increased activity
• vascular alpha-adrenergic receptors : increased venous return and increased arterial resistance
• Myocardial B-adrenergic receptors: increased heart rate and increased myocardial contractility
• increased energy consumption
  -increased actin-myosin crossbridging
• increased calcium delivery to myofibrils
• increased intra-cellular cAMP ( myocyte destruction and apoptosis)
• catecholamine metabolism _ free radicals

Question 4

B1 adrenergic activation beneficial and adverse effects?

Answer 4

beneficial : increased myocardial contractility and increased cardiac output

adverse: increased myocardial oxygen consumption
- increased cAMP - increased intracellular calcium, calcium overload, myocardial necrosis
- increased vasoconstriction - peripheral tissue anoxia
- arrythmogenesis

Question 5

compensatory mechanism for HF: RAAS

Answer 5

• low renal artery pressure
• check on google

Question 6

actions of angiotensin 2

Answer 6

• direct vasoconstrictor effect on vessels
• ↑ nor adrenaline release → vasoconstriction
• Endothelin 1 formation - potent vasoconstrictor , cardiac hypertrophy
• mild inotropic effect via ↑ calcium influx
• release of growth factors from vascular smooth muscle cells PDGF, TGF B1, FGF
• activates proto-ocogens like c-fos
• Phospholipase C activation : stimulation of cell growth, collagen synthesis by fibroblasts

Question 7

other activated compensatory systems : CYTOKINES

Answer 7

• ↑ Tumor necrosis factor
  → oxidative stress
  → inducible nitric oxide
  synthase (increase NO)
  →cachexia
• platelet derived growth factor
• fibroblast growth factor
• transforming growth factor Beta

Question 8

explain the concept of oxidative stress

Answer 8

• Oxidant metabolites exert toxic effects: ↑ production, ↓ protection, induction of apoptosis
• oxygen free radicals :
  
  • Xanthine oxidase
    - Activated neutrophils
    
    • catecholamine autoxidation

ANTIOXIDANTS:
- Superoxide dismutase, Catelase, Gluthione peroxidase, Vitamin E, Vitamin C, cysteine

Question 9

explain the 4 mechanisms of heart failure

Answer 9

1. Myocardial ischemia
   - Altered contractility and relaxation
   - depletion of energy stores
   - reduced sensitivity of contractile proteins to calcium
   hibernating myocardium
2. Myocardial infarction
   - myocyte necrosis
   - remodelling
   - myocytes replaced by fibrous tissue
3. myocyte destruction of unkown origin - cardiomyopathy
4. known toxic agents: alcohol, cytotoxic drugs

Question 10

CLINICAL PRESENTATION: SYMPTOMS

Answer 10

• Exertional dyspnoea NYHA FC 2-4: 2 degree to pulmonary capillary hypertension, increased LA & LV filling pressures
• Paroxysmal Nocturnal Dyspnoea
• Orthopnea : increased pulmonary venous congestion
• fatigue and weakness
• cough: dry, productive, pink frothhy sputum
• leg oedema
  – abdominal distention
• anorexia and weight loss

Question 11

PHYSICAL FINDINGS

Answer 11

1. EVIDENCE OF ↑ ADRENERGIC ACTIVITY
   - tachycardia
   - peripheral vasoconstriction : pallor and cold extremities
2. SYSTEMIC VENOUS HYPERTENSION:
   - ↑ JVP
   - hepatojugular reflex
   - hepatomegaly
   - Ascites
   - leg oedema
3. PULMONARY VENOUS HYPERRTENSION
   - basal inspiratory crackles
   - pleural effusion
4. CARDIAC
   - cardiomegaly - displaced apex bbeat
   - added sounds: S3 and S4
   - murmurs

Question 12

INVESTIGATIONS

Answer 12

→ ELECTROCARDIOGRAM:
- Rhythm, rate, R wave, ST depression/elevation Q waves

→ECHOCARDIOGRAM
- structural and functional information, chamber size, LVEF, valve morphology and severity of dysfunction
- pericardium: effusion/constriction

→ CHEST XRAY
→ LABORATORY INVESTIGATIONS: biochemistry

Question 13

INVESTIGATIONS (bnp)

Answer 13

• BNP: 32 amino acid polypeptide
• NT-proBNP: 76 amino acid inactive pro- hormone
• Poduced in the heart (ventricles), brain, in response to wall stretch
• inhibit RAAS, partially inhibit SS
• Functions: diuretic, natriuretic, hypotensive

Question 14

BNP & pro-BNP uses

Answer 14

• differentiating between dyspnoea due to cardiac/respiratory causes
• assessing prognosis
  -titrating anti-failure therapy

Question 15

ACC/AHA Classification of heart failure Stage A

Answer 15

• at high risk, no structural heart disease:
  
  • hypertentsion
  • lipid disorders
  • type 2 DM
    treat underlying condition
    lifestyle modification

Question 16

ACC/AHA CLASSIFICATION OF HEART FAILURE: STAGE B

Answer 16

• asymptomatic structural heart disease
• valve lesion
• congenital heart disease:
  
  • ACE Inhibition B-blockade

Question 17

ACC/AHA CLASSIFICATION OF HEART FAILURE: STAGE C

Answer 17

• structural heart disease
• previous or current heart failure symptoms
• diuretics
• ace inhibition
  salt restriction

Question 18

ACC/AHA CLASSIFICATION OF HEART FAILURE: STAGE D

Answer 18

• refractory heart failure: mechanical assist devices
• IV inotropic support
• heart transplantation
  hospice care

Question 19

heart failure : treatment

Answer 19

• valve repair/replacement
• angioplasty
• CABG
• Correction of congenital diseases

*FOR HIDDEN CONDITIONS
- aortic stenosis, mitral stenosis, ASD , Ischaemic heart disease with silent ischemia
- exercise echocardiogram
- dobutamine stress echocardiogram