PATHOLOGY - Cardiac Pathology Flashcards
(190 cards)
What is heart failure?
Heart failure is when the heart is unable to pump enough blood around the body to meet the body’s demand
What are the six underlying mechanisms of heart failure?
Pump failure
Obstruction
Regurgitated blood flow
Shunted blood flow due to congenital disease
Heart/major blood vessel rupture
Cardiac conduction disorders (arrhythmias)
What are the three clinical signs of acute heart failure?
Intermittent weakness
Syncope
Sudden death
What is syncope?
Syncope is the loss of consciousness for short periods of time caused by cerebral hypoperfusion
What causes sudden death in acute heart failure?
Cardiogenic shock (cells don’t receive enough oxygenated blood leading to cell death) and acute pulmonary oedema
What is congestive heart failure?
Congestive heart failure is chronic heart failure which leads to congestion and consequential oedema around the body
What are the two classifications of heart failure based on pumping ability?
Systolic heart failure
Diastolic heart failure
What is systolic heart failure?
Systolic heart failure is a failure in ventricular contraction during systole
What is diastolic heart failure?
Diastolic heart failure is a failure in ventricular relaxation/ventricular filling during diastole
What are the three anatomical classifications of heart failure?
Left-sided heart failure
Right-sided heart failure
Biventricular heart failure
What are the consequences of left sided heart failure?
Left sided heart failure is when the left ventricle is unable to pump enough blood into the aorta, causing tissue hypoperfusion. In addition, left-sided heart failure can cause a backup of blood into the pulmonary veins and pulmonary circulation, causing pulmonary congestion, increasing hydorstatsic pressure, resulting in pulmonary oedema
What are the four main clinical signs of left-sided heart failure?
Tissue hypoperfusion
Pulmonary congestion/oedema
Dyspnoea
Coughing
What is a key histological sign of chronic left-sided heart failure?
Haemosiderin-laden macrophages (heart failure cells)
What are Haemosiderin-laden macrophages (heart failure cells)?
The pulmonary congestion caused by left-sided heart failure can cause erythrocytes and proteins to leave the blood vessels into the alveoli where they will be engulfed by alveolar macrophages, leading to the formation of haemosiderin-laden macrophages (heart failure cells)
How does left-sided heart failure initially cause left ventricular hypertrophy?
When there is decreased cardiac output, this triggers vasoconstriction and hypertension to maintain core tissue perfusion (heart and brain). However, this hypertension causes increased arterial pressure and thus increased afterload and increased cardiac workload, which can lead to hypertrophy of the left ventricle. Initially, this hypertrophy serves as a compensatory mechanism to maintain cardiac output
What are the long-term effects of left ventricular hypertrophy?
Over time, left ventricular hypertrophy will reduce the ability of the ventricle to relax leading to impaired ventricular filling and thus a decrease in stroke volume and cardiac output
How does the renin-angiotensin aldosterone system respond in response to left-sided heart failure?
When there is decreased perfusion of this kidneys, this will activates the renin-angiotensin aldosterone system. This will lead to sodium and water reabsorption and increased fluid retention, thus increasing the blood volume that is entering the left ventricle, increasing contractility, stroke volume and cardiac output
What is the harmful effect of renin-angiotensin aldosterone system activation in response to left-sided heart failure?
The renin-angiotensin aldosterone system increases blood volume which will increase the back up of blood into the pulmonary veins and pulmonary circulation, worsening the pulmonary congestion and oedema. Increasing the blood volume will also increase the central venous pressure and the preload
How does the sympathetic nervous system respond to left-sided heart failure?
The sympathetic nervous system causes an increase in the heart rate to increase cardiac output, causes vasoconstriction to redirect blood to core tissues (heart and brain) and activates the renin-angiotensin aldosterone system
What are the consequences of right sided heart failure?
Right sided heart failure is when the right ventricle is unable to pump enough blood into the pulmonary trunk, causing pulmonary hypoperfusion. In addition, right-sided heart failure can cause a backup of blood into the cranial and caudal vena cavae and systemic circulation, causing systemic congestion resulting in systemic oedema
What are the five main clinical signs of right-sided heart failure?
Pulmonary hypoperfusion
Jugular venous distension
Ascites
Hepatomegaly
Splenomegaly
What is ‘nutmeg’ liver?
‘Nutmeg’ liver is the mottled appearance of the liver as a result of chronic hepatic venous congestion
What is the term used to describe right-sided heart failure caused by respiratory disease or dysfunction?
Cor pulmonale
How can high altitude disease (brisket disease) cause cor pulmonale?
Increased altitude causes hypoxaemia leading to pulmonary vasoconstriction and pulmonary hypertension, increasing the arterial pressure and afterload, so the right side of the the heart has to contract more to overcome this resistance to eject blood into the pulmonary trunk and into the lungs