Cardiovascular Pathology 2 Flashcards
Define heart failure
Inability of the heart to pump enough blood needed to meet the metabolic demands of the tissue
Causes of heart failure:
- Coronary artery disease
- Hypertension
- Cardiomyopathy
- Arrhythmias
- Valvular disease
- Congenital heart disease
- Anaemia
- Thyroid disease
- Alcohol
What is congestive cardiac failure?
HF specifically refers to the stage in which fluid builds up within the heart and causes it to pump inefficiently.
CHF can occur over time or acutely. What would cause CHF to occur acutely?
Acute haemodynamic stress e.g. fluid overload and large MI
CHF can occur over time. What are the 2 main factors that can cause this to happen?
The cumulative effects of chronic workload:
- Hypertension and/or
- Valve diseases
How does chronic workload lead to CHF?
- Cardiac myocytes are stretched –> stimulates hypertrophy and sometimes dilatation
- LV tries to adapt; thickened left ventricular wall leading to decreased space in left ventricular chamber
- Myocytes then overstretch and lose elasticity; thinner ventricular wall and increased space in left ventricular chamber
- This leads to heart failure and arrhythmias
As the heart fails, the body tries to compensate.
a) How is HR affected?
b) How is contractility affected?
c) How is fluid volume affected?
a) HR is increased via release of noradrenaline
b) Contractility is increased via release of noradrenaline
c) Fluid volume is adjusted via activation of RAAS and release of ANP
What is ANP? Effect?
Atrial natriuretic peptide (ANP) is a cardiac hormone that regulates salt-water balance and blood pressure by promoting renal sodium and water excretion and stimulating vasodilation.
Pathogenesis of LS heart failure:
What is the Frank-Starling mechanism?
Is the description of cardiac hemodynamics as it relates to myocyte stretch and contractility:
Stroke volume of the left ventricle will increase as the left ventricular volume increases due to the myocyte stretch causing a more forceful systolic contraction.
Function of this stroke volume adjustment described by Starling’s Law?
This allows the cardiac output to be synchronised with the venous return and the arterial blood supply.
The clinical effects of LS heart failure are due to which 3 main factors?
- Low cardiac output
- Hypoperfusion of tissues
- Pulmonary congestion
Why can heart failure lead to pulmonary oedema?
When the heart is not able to pump efficiently, blood can back up into the veins that take blood through the lungs. As the pressure in these blood vessels increases, fluid is pushed into the air spaces (alveoli) in the lungs.
What are heart failure cells? Where are they seen?
- WHAT: Macrophages containing hemosiderin generated in the alveoli of patients with left heart failure or chronic pulmonary edema
- When the high pulmonary blood pressure causes RBCs to pass through the vascular wall where they break down; hemosiderin is one of the breakdown products
What are the respiratory signs and symptoms seen in LS heart failure?
- Oedema
- Dyspnoea
- Orthopnoea – ask about pillows!
- PND (paroxysmal nocturnal dyspnoea) – attack of severe SOB and coughing, generally occurs at night
- Blood tinged sputum
- Cyanosis
- Elevated pulmonary ‘WEDGE’ pressure (PCWP) i.e. pulmonary hypertension
How does LS heart failure affect the kidneys?
Reduced renal perfusion
How does heart failure affect the levels of nitrogenous waste products in the blood? What is this condition called?
1) Inadequate perfusion to kidney causes body to increase the intraglomerular hydrostatic pressure in an effort to support glomerular function
2) This leads to rise in blood urea nitrogen (BUN) concentration (and serum creatinine)
This is called pre-renal azotemia
How can reduced renal perfusion due to heart failure affect RAAS? What is the effect of this?
- RAAS is activated in patients with heart failure causing salt and fluid retention –> this causes expansion of interstitial and intravascular fluid volume
- This can can further volume overload a failing system
What neurological effects can advanced cardiac failure lead to?
- Cerebral hypoxia
- Irritability
- Restlessness, stupor, coma
What are the 2 major causes of right sided heart failure?
1) Left sided heart failure
2) Cor pulmonale
How can LS HF lead to RS HF?
- LV pumps inefficiently causing a backlog of blood in left side of heart
- RV continues to pump blood as normal – blood turns into a traffic jam when it gets to left side of heart
- Traffic jam eventually causes blood to back up into the lungs – right side of heart then has to work harder to push blood
What is cor pulmonale?
RS HF secondary to pulmonary hypertension; high blood pressure within lungs can cause enlargement of RV
RS HF leads to engorgement of systemic and portal venous systems. This can affect the liver and spleen. What symptoms can show this?
Due to portal vein congestion:
- Passive congestion (nutmeg liver)
- Congestive splenomegaly
- Ascites
- Congestion and oedema of bowel wall
What effects can systemic venous congestion seen in heart failure have on the pleura/pericardium?
- Pleural and pericardial effusions
- Transudates
- Oedema of peripheral and dependent parts of body
Does systemic venous congestion lead to the formation of transudates or exudates?
Transudates
Valvular heart disease can be divided into opening and closing problems. What are examples of each?
Opening; stenosis
Closing; regurgitation, incompetence, insufficiency
What does an ‘opening problem’ in valvular heart disease mean? What can this lead to?
- Failure of valve to open completely, impeding forward flow
- Leads to pressure overload of the heart
What are opening problems seen in VHD almost always due to?
Almost always due to chronic abnormality of valvular leaflet caused by relatively few disorders
What does a ‘closing problem’ in valvular heart disease mean? What can this lead to?
- Failure of valve to close completely allowing reverse flow
- Leads to volume overload of the heart
What can closing problems in VHD result from?
- Can result from intrinsic disease of the valve cusps or damage to the supporting structures
- Has many causes and may appear acutely or chronically
Which type of VHD leads to pressure overload?
Opening problem; impedes forward flow
Which type of VHD leads to volume overload?
Closing problems; allows reverse flow
One of the major forms of VHD is acquired aortic stenosis. What are 3 causes of this?
- Calcification of a deformed (congenitally bicuspid) valve (50-70y age group)
- Senile calcification of anatomically normal aortic valve (>70y age group)
- Rheumatic heart disease; a condition in which the heart valves have been permanently damaged by rheumatic fever
What is calcific aortic stenosis (AS)?
It is characterised by progressive fibro-calcific remodelling and thickening of the aortic valve leaflets that, over years, evolve to cause severe obstruction to cardiac outflow.
What can acquired AS lead to?
- LVH (not caused by hypertension)
- Ischemia
- Cardiac decompensation, angina, CHF
- 50% die in 5 years if angina present
- 50% die in 2 years if CHF present !!!
What is acquired mitral stenosis (MS) virtually synonymous with?
Rheumatic heart disease
What is the most common valvular abnormality?
Calcific aortic stenosis
What is calcific aortic stenosis usually the consequence of?
- Age-related wear and tear of normal/bicuspid aortic vale (bicuspid valve undergoes more mechanical stress and so becomes stenotic earlier)
- Hyperlipidaemia
- Hypertension
- Inflammation
is the aortic or mitral valve more often affected by calcification?
Aortic valve; mitral valve is generally normal but can be involved by extension of calcific deposits
What are the effects of calcific aortic stenosis?
- Leads to 2x gradient pressure, left heart hypertrophy, ischaemia
- Long term complications
- Cardiac decompensation
- Angina (50% die within 5 years)
- Congestive heart failure (50% die within 2 years)
What valve does rheumatic heart disease most commonly affect?
Mitral valve (70%) but can also affect aortic valve (25%) and tricuspid and pulmonary valves (very rarely)
What does rheumatic heart disease follow?
A group A strep (S. pyogenes) infection; anti-strep antibodies cross-react in the heart
What are the subclassifications of rheumatic HD?
- Pancarditis
- Endocarditis
- Myocarditis
- Pericarditis
What acute pathophysiology is seen in mitral stenosis following a group A strep infection?
- Inflammation
- Aschoff bodies
- Anitschkow cells
- Pancarditis
- Vegetations on chordae tendinae at leaflet junction
What are Aschoff bodies?
result from inflammation associated with rheumatic heart disease
What are Anitschkow cells?
enlarged macrophages found within granulomas, associated with rheumatic heart disease
What is pancarditis?
Pancarditis, also called perimyoendocarditis, is the inflammation of the entire heart: the pericardium, the myocardium and the endocardium.
What chronic pathophysiology is seen in mitral stenosis following a group A strep infection?
- Thickened valves
- Commissural fusion
- Thick, short, chordae tendinae