Case 12 Flashcards
What is hypoxia?
Reduced level of oxygen in tissues
What is anoxia?
Severe form of hypoxia
No oxygen supply to tissues
What is ischaemia?
Reduced blood supply to part of the body
This leads to decreased oxygen supply to affected tissues
No removal of substances
What is cardiac metabolism?
The set of reactions in the cells of the heart which converts nutrients into ATP (energy)
What is fatty acid oxidation?
Fatty acids broken down to produce energy
Effect of hypoxia and ischaemia on metabolism?
1) Shifts metabolism toward anaerobic pathways (don’t require oxygen)
2) Increased reliance on glycolysis for ATP production
3) Impaired fatty acid oxidation (less energy produced from fatty acids)
4) Accumulation of lactate and decreased ATP levels
5) Anaerobic metabolism causes cellular acidosis (acidic cells) and compromised organ function
Repurfusion meaning?
Restoration of blood flow after reduced or interrupted supply
What are reactive oxygen species?
Highly reactive molecules containing oxygen
They are natural bi-products of normal cellular metabolism
How can repurfusion damage cellular components?
The blood flow is restored and the sudden influx of oxygen can lead to a burst of reactive oxygen species production.
This can damage cellular components
Glycolysis reaction?
Glucose + ADP + Pi —> ATP + Lactate + H+
ATP production using phosphocreatine reaction?
Phosphocreatine + ADP —> ATP + Creatine
Reaction when ATP is used?
ATP —> ADP + Pi
Infarction meaning?
Death of a tissue due to lack of blood supply
What happens to cells during infarction?
ATP levels are low
Ion pumps have no fuel
Ion levels in cells rise (Na+ and Ca2+)
This causes cells to swell and be damaged
Mitochondria release cell death trigger factors
Cell necrosis meaning?
Cell death caused by external factors
Examples of anoxic and ischaemic damage in organs?
Heart (infarction)
Brain (stroke)
Kidney (acute renal failure)
Pancrease (Pancreatitis)
… it can happen to all organs
3 layers of a blood vessel?
Tunica Intima (inner)
Tunica Media (middle)
Tunica Adventitia (outer)
Tunica - means layer
Describe tunica intima?
Endothelium supported by connective tissue
Describe tunica media?
Smooth muscle cells and elastic fibres
Describe tunica adventitia?
Collagenous connective tissue, nerve endings
Atherosclerosis?
Chronic inflammatory process triggered by accumulation of cholesterol-containing low-density lipoprotein particles in arterial wall.
Lipoproteins?
Contain proteins, phospholipids, cholesterol and triglycerides
Transport lipids in blood stream
Chylomicrons?
Lipoproteins which transport dietary triglycerides from intestines to cells
Very Low Density Lipoprotein?
Transports triglycerides synthesised in liver to various tissues
Intermediate Density Lipoprotein?
Formed from degradation of very low density lipoprotein. Will further degrade in low density lipoprotein.
Transports cholesterol and triglycerides
Low Density Lipoprotein?
Transports cholesterol and triglycerides in blood stream
This is ‘bad cholesterol’
Can contribute to build up of plaque in arteries
High Density Lipoprotein?
Removes excess cholesterol from blood stream by transporting it to liver for excretion or recycling
“Good cholesterol”
High HDL levels help prevent build up of plague, can be achieved by healthy lifestyle
Explain path of blood through the heart?
1)Deoxygenated blood enters right atrium via superior and inferior vena cava
2)Blood moves through tricuspid valve into right ventricle
3)Right ventricle contracts and pumps blood through pulmonary valve into pulmonary artery
4)Blood enters lungs and is oxygenated
5)Pulmonary veins return blood to left atrium
6)Blood passes through mitral valve into left ventricle
7)Left ventricle contracts and oxygenated blood moves into aorta via aortic valve
8)Aorta distributes oxygenated blood around body
What is systole?
Contraction
What is diastole?
Relaxation
What is preload?
Blood which fills heart
What is venous return?
Volume of blood which fills ventricles during each diastole
What is adrenergic stimulation?
Activation of receptors by adrenaline binding
How does adrenergic stimulation increase cardiac output?
Increased heart rate, increased contractility, accelerated relaxation, accelerated conduction
How to calculate ejection fraction?
Stroke volume/ end diastolic volume
How to calculate stroke volume?
End diastolic volume - end systolic volume
What is systolic dysfunction?
When ejection fraction is <55%
What is diastolic dysfunction?
Abnormal relaxation and/or increased ventricular stiffness
What is heart failure?
Heart unable to pump enough blood to meet body’s needs
Caused by structural and/or functional abnormalities of heart
Causes of heart failure?
Coronary heart disease
High blood pressure
Cardiomyopathy
Heart valve disorders
Previous heart attacks
Infections
Arrhythmias
Diabetes - damage to blood vessels and nerves
Obesity
Sleep apnea
What is left heart failure?
Left side of heart unable to pump blood effectively to body
Symptoms of left heart failure?
Shortness of breath
Fatigue and weakness
Persistent coughing or wheezing - white/pink/frothy sputum
Fluid retention
Cardiac arrhythmia
Reduced exercise tolerance
Difficulty concentrating
What is right heart failure?
Right side of heart unable to pump blood effectively to lungs
This can lead to a build up of fluid in body
Symptoms of right heart failure?
Swelling in legs/ankes/feet
Enlargement/tenderness of liver
Abdominal fluid accumulation
Shortness of breath
Fatigue and weakness
Reduced appetite and nausea
Increased heart rate
Cyanosis (blue discolouration of lips or skin) - when severe
How are different heart failures classified?
Class 1 - 4
What are the 2 types of heart failure?
1) Heart failure with reduced ejection fraction/ systolic heart failure
2) Heart failure with preserved ejection fraction/ diastolic heart failure
Describe systolic heart failure?
Hearts left ventricle becomes weak and is unable to pump blood effectively (leading to reduced ejection fraction)
What is chronic beta adrenergic stimulation in heart failure?
Heart is constantly being stimulated meaning it works too hard and can become damaged
What are ICDs - implantable cardioverter defbrillator?
Implantable cardioverter defibrillator
Detects and treats irregular heart rhythms in order to avoid cardiac arrest
Delivers electric shocks
What is CRT - cardiac resynchronisation therapy?
Use of a pacemaker to pace left and right ventricles simultaneously to synchronise contraction - increasing cardiac efficiency
Describe how a heartbeat is generated?
1)Sinoatrial node spontaneously depolarises, generating an electrical impulse which spreads across atria, causing them to contract and push blood into ventricles.
2)Electrical impulses reach atrioventricular nodes located near the bottom of the right atrium. The AV node delays signal slightly to allow ventricles to fill.
3)Electrical impulses travel down to bundle of His, which conduct signal from atria to ventricles
4)Bundle of His divide into Purkinje fibres which spread throughout ventricles and cause them to contract from bottom up and expel blood
5)After contraction, heart depolarises to ‘reset’ ready for next heart beat
Describe process of depolarisation of SA node cells?
1)Slow influx Na+ ions into cell via Na channels depolarises cell
2)Rapid influx of Ca2+ ions through Voltage gated Calcium ion channels further depolarises cell
Describe process of repolarisation of SA node cells?
K+ ions leave cell via K channels, restoring the negative charge inside cell
What is a syncytium?
When cardiac muscle cells are interconnected by intercalated discs, so they function as a single unit during contraction.
What is a gap junction?
They allow for exchange of ions, small molecules and electrical signals between adjacent cells.
Clusters of connexin proteins form channels between cell membranes
Effect of sympathetic autonomic nervous system on heart?
Increase heart rate
Increase atrioventricular node conduction speed
Decreased action potential duration
Effect of parasympathetic autonomic nervous system on heart?
Decreased heart rate
Decreased atrioventricular node conduction speed
What is hypertension?
An increase in peripheral vascular resistance when cardiac output is normal
What is systolic pressure?
Pressure in arteries when heart contracts to pump blood out (maximum pressure value in arteries)
What is diastolic pressure?
Pressure in arteries when heart is relaxed and filling up with blood (minimum pressure value in arteries)
What is diastolic pressure?
Pressure in arteries when heart is relaxed and filling up with blood (minimum pressure value in arteries)
What do the numbers mean in blood pressure readings?
Top number - systolic pressure
Bottom number - diastolic pressure
What is a healthy blood pressure value?
Below 120/80
Above what value is classed as hypertensive?
140/90
Primary vs Secondary hypertension?
PRIMARY - develops gradually over time, no identifiable cause, often genetics, lifestyle and aging contribute
-most common type
SECONDARY - has specific underlying cause and often develops more rapidly
-The underlying cause must be treated
Examples of causes of secondary hypertension?
Drugs and medications, kidney problems, hormonal imbalance, obstructive sleep apnea, adrenal gland tumours, thyroid disorder.
What is hyperaldosteronism?
Overproduction of aldosterone
Function of aldosterone?
Regulates sodium and potassium levels in body, affecting blood pressure
What is primary hyperaldosteronism?
Abnormality (often a non cancerous growth) in adrenal glands leading to excessive production of aldosterone
What is secondary hyperaldosteronism?
Aldosterone production is increased due to another condition - eg kidney disease, heart failure or liver cirrhosis
Symptoms of hyperaldosteronism?
High blood pressure, low potassium levels, fatigue, fluid retention
What is an atheroma?
An accumulation of (intracellular and extracellular) lipids in the intima of large and medium size arteries
How is an atheroma formed?
1)Endothelium of artery is damaged - eg by hbp or high cholesterol
2)LDL cholesterol seeps into damaged area
3)Cholesterol is oxidised
4)White blood cells are attracted to area and ingest oxidised cholesterol and form foam cells
5)Over time foam cells and other substances accumulate and form a plaque in the artery wall
6)This narrows arteries
Stages of atheroma development?
1)Endothelium of artery damaged
2)LDL cholesterol seeps into damaged endothelium and leads to formation of fatty streaks
3)Inflammatory cells and smooth muscle cells accumulate and simple plaque is formed
4)Sometimes there is a buildup of cholesterol chrystals and calcium or there are areas of haemorrhage or ulceration. This is a complicated plaque.
What is arteriosclerosis?
Thickening of walls of arteries and arterioles (usually due to hypertension or diabetes mellitus)
What is simple atheromatous plaque?
Extracellular lipid in intima within modified smooth muscle cells. It has a fibrous cap, has blood vessel proliferation and inflammatory cells are present.
Examples of complications of an atheromatous plaque?
Calcification
Plaque disruption
Haemorrhage into plaque
Thrombosis
Aneurysm formation
What is an aneurysm?
Excessive localised swelling in arterial wall
Give examples of common sites of atheroma?
Aorta - especially abdominal
Coronary arteries
Carotid arteries
Cerebral arteries
Leg arteries
Risk factors for atheroma?
Smoking, male, menopause, diet, alcohol, obesity, hyperlipidaemia (familial or aquired), diabetes, lack of exercise, stress, infection, oral contraceptives
What is hyperlipidaemia?
Elevated lipid conc in blood
What is ischaemia?
Reduced delivery of blood to an organ/organ part, leading to compromised function
What is infarction?
Reduced delivery of blood to an organ/organ part, leading to its death
What is peripheral vascular disease?
Reduced circulation of blood to a body part other than heart and brain
What is ischaemic/coronary heart disease?
Blood vessels supplying heart are narrowed or blocked
Give examples of potential consequences of ischaemic heart disease?
Cardiac arrhythmia
Angina pectoris
Acute myocardial infarction
Acute left ventricular failure
Chronic heart failure
Sudden unexpected death
What is cardiac arrhythmia?
Irregular heart beat
What is angina pectoris?
Chest pain caused by reduced blood flow to heart muscle
What is stable angina?
Predictable and usually occurs during physical exertion or emotional stress
What is unstable angina?
Unpredictable episodes of chest pain which occur - even at rest
What is acute myocardial infarction?
A HEART ATTACK
Sudden blockage of blood flow to part of heart muscle (eg because of sudden rupture of a plaque in one of the coronary arteries)
What is a STEMI?
ST Segment Elevation Myocardial Infarction
Complete blockage of coronary artery
Elevation of ST segment of ECG
What is a NSTEMI?
Non ST Segment Elevation Myocardial Infarction
Partial blockage or severe narrowing of coronary artery
No significant elevation of ST segment of an ECG
What is acute left ventricular failure?
Left ventricle of heart unable to pump blood effectively to rest of body
What is chronic heart failure?
Heart is unable to pump blood efficiently to meet body’s needs over time
Most common causes of MI?
-Rupture of an atherosclerotic plaque in coronary artery
-Formation of intracoronary thrombus causing infarction downstream of occluded blood vessel
What is cardiac remodelling?
Changes to structure and function of heart following injury or stress
Alterations to size/shape/function of heart chambers and changes in composition of heart muscle
How can myocardial infarction lead to heart failure?
1)Coronary artery is blocked
2)Ischaemia and myocardial infarction
3)Necrosis
4)Inflammatory response to remove dead cells
5)Infarct heals and scar tissue forms
6)Hypertrophy, dilation and reduced function
7)This can lead to heart failure
Explain the inflammatory response to MI?
1)MI occurs
2)Cells die via necrosis
3)Cells release intracellular contents and intiate intense inflammatory response
4)Cardiomyocytes release troponins which are used to asses cardiac injury
5)Neutrophils infiltrate area of infarction
6)Neutrophils secrete MMPs (matrix metalloproteinases) and phagocyte debris
7)levels of pro inflammatory cytokines increase (triggers inflammation) - so more immune cells recruited
8)Neutrophils undergo apoptosis
9)Macrophages remove dead cells
10)More inflammatory cells are recruited and healing process is initiated
Describe process of infarction healing and scar formation?
1)Cardiac fibroblasts turn into myofibroblasts and secrete new ECM proteins (extracellular matrix)
2)Myofibroblasts are cleared by apoptosis
What are ECM proteins?
Extracellular matrix proteins
Provide structural and biochemical support to cells within tissues and organs
What is Ejection Fraction?
Measurement of percentage of blood pumped out of left ventricle - used to evaluate cardiac function
Describe action of platelets?
1)Blood vessel damaged
2)Platelets activated
3)Platelets adhere to site of injury to exposed collagen fibres in damaged blood vessel
4)Adhesed platelets release cytokines which stimulate other platelets
5)Platelets aggregate (stick to each other)
6)Blood clot forms at injury site
7)Promotes healing of damaged blood vessel
8)Platelets contract, pulling edges of healing wound together
9)Clot dissolves and blood vessel heals
What is the main protein in blood clots?
Fibrin
What is hyperlipidaemia?
High fat levels in blood (including cholesterol and triglycerides)
What is atherosclerotic plaque?
Build up within walls of arteries
This can cause narrowing and harden arteries, leading to reduced blood flow to organs and tissues.
What type of medication is Atorvastatin?
Statin
Function of statins?
Lower LDL cholesterol by inhibiting a enzyme in liver which plays a key role in their production
Function of fibrates?
Lower triglyceride levels
Function of ezetimibe?
Blocks absorption of cholesterol from digestive tract, reducing LDL cholesterol levels
Function of nitroglycerin/glycerol trinitrate?
Relaxes and widens blood vessels
What type of medication is Bisoprolol?
Beta blockers
How can beta blockers be used to treat angina?
Blocks effect of adrenaline
Decrease hearts workload and oxygen demand by slowing hr and reducing bp
How can calcium channel blockers be used to treat angina?
Relax and widen blood vessels
How can aspirin be used to treat coronary heart diseases?
Prevents blood clot formation
What type of drug is ticagrelor?
Antiplatelet drug
Purpose and function of antiplatelet drugs?
Inhibit platelet aggregation - to prevent arterial thrombosis
Purpose and function of anticoagulants?
Inhibits formation of fibrin (main protein in blood clots) , used to prevent venous thrombosis
Purpose and function of thrombolytic/fibrinolytic agents?
Dissolves already formed blood clots by activating the body to break down fibrin (main protein in blood clots)
What type of drug is Ramipril?
Angiotensin-converting-enzyme (ACE) inhibitor
Function of ACE inhibitors?
Angiotensin-converting-enzyme plays a role in blood pressure regulation and fluid balance. ACE inhibitors inhibit it. This is commonly used to treat hypertension, heart failure and to reduce risk of cardiovascular events.
What is an angioplasty?
Widens narrowed coronary arteries
A stent is inserted into artery to hold it open.
Describe process of stent insertion?
1)Angiogram taken and blockages identified
2)Stent (small mesh tube) is mounted on balloon catheter and guided to blockage site
3)Balloon is inflated, which compresses stand against artery walls, opening them up
4)Balloon removed but stent stays in place
What is coronary artery bypass surgery?
Reroutes blood flow around blocked arteries by using transplanted vessels from other parts of the body.
Which part of ECG shows atrial depolarisation/contraction?
P wave
Which part of ECG shows ventricular depolarisation/contraction?
QRS complex
What is PR interval?
Time between P wave and start of QRS complex
What is T wave?
Ventricular repolarisation (ventricular relaxation)
What is ST segment?
Period between QRS (ventricular depolarisation) and T wave (ventricular repolarisation)
Should be at the base line
What is the QT interval?
From beginning of QRS wave to the end of the T wave
What is P-P interval?
Time between successive P wave complexes (Time between atrial contractions)
What is R-R interval?
Time between successive QRS complexes (Time between ventricular contractions)
What is first degree heartblock?
Delay in electrical signals moving from atria to ventricles
How can you detect first degree heartblock on an ECG?
Prolonged PR interval in ECG
What is second degree heartblock?
Not all signals from atria reach ventricles so ventricles don’t always contract
How can you detect second degree heartblock on an ECG?
Intermittent absence of QRS complex
Prolongation of PR interval
What is complete heart block?
Complete blockage of electrical impulses between atria and ventricles
Atria and ventricles beat independently, leading to slow heart beat and potential loss of coordination between the 2 chambers
How can complete heart block be detected on ECG?
No association between P waves and QRS complexes
Atria have normal rate, ventricle is slower
Regular P-P intervals
Irregular R-R intervals
What is sinus arrhythmia?
Heart rhythm fluctuates with breathing cycle
Increases during inhalation and decreases during exhalation
How to detect sinus arrhythmia on ECG?
Minor variations in heartbeat
What is ventricular asystole?
Absence of electrical activity and contractions in ventricles of heart (type of cardiac arrest)
How does ventricular asystole appear on ECG?
A flat line
What is atrial fibrillation?
Irregular, uncoordinated and rapid beating of atria
How to detect atrial fibrillation on ECG?
Absence of P waves
Irregular R-R intervals
Narrow QRS complex
Fast heart rate
What is ventricular fibrillation?
Rapid and uncontrolled quivering of ventricles - they don’t contract
How to detect ventricular fibrillation on ECG?
Absence of organised QRS complexes
Absence of P waves and T waves
Irregular and erratic waveform
What is indicated by ST segment elevation?
Myocardial infarction (heart attack)
What is indicated by ST segment depression?
Myocardial ischaemia (inadequate blood supply)
What is indicated by ST segment flattening?
Early signs of myocardial ischaemia
Where does anterior descending branch of left coronary artery supply?
Anterior wall of left ventricle including apex and front part of septum
Where does left circumflex artery supply?
Lateral wall of left ventricle and sometimes left atrium
Where does right marginal branch of right coronary artery supply?
Lateral wall of right ventricle
Where does posterior descending branch of right coronary artery supply?
(AKA -posterior inter ventricular artery)
Posterior walls of both ventricles and inferior part of interventricular septum
What is echocardiograph and what does it show?
Uses sound waves to create image of heart.
The practitioner places an ultrasound probe on the chest. The waves bounce off structures in heart and create real-time images on a monitor. Used to diagnose structural abnormalities and assess cardiac function.
What is an angiogram?
Contrast dye is injected into blood and then an X ray is taken in order to visualise blood vessels
What is referred pain?
Pain is felt in a different part of the body than where it originates from due to nerves haring pathways to the brain
How can this be clinically presented, especially for cardiac patient?
Pain originating from heart can be felt in other areas of the body instead such as left side of chest, left arm, neck, jaw, shoulders and upper back.
This can often happen in heart attacks
What is angina?
Chest pain when heart muscle doesn’t get enough oxygen rich blood
Signs and symptoms of angina?
-Pressure/squeezing/tightness/heaviness in chest
-Usually lasts less than 10 mins
-Often triggered by physical exertion, stress or cold exposure
-May be accompanied by shortness of breathe, sweating, nausea or fatigue
Management for angina?
IMMEDIATE - Rest and/or sublingual nitroglycerin (dilates blood vessels)
LONG TERM - Lifestyle changes, medications, angioplasty, stenting.. Depending on severity
What is myocardial infarction?
(AKA heart attack)
Blood flow to part of heart is blocked for long enough that part of heart muscle is damaged/died
Signs and symptoms of myocardial infarction?
-Severe crushing/tightness in chest which may radiate to left arm, jaw, back or neck
-Persistant pain and not resolved with rest or medications
-May be accompanied by shortness of breathe, nausea, vomiting, lightheadedness, loss of consciousness
Management of myocardial infarction?
IMMEDIATE - Aspirin, Nitroglycerin, Oxygen, potential procedures to restore blood flow to blocked artery
LONG TERM - medications to prevent re-occurrence, lifestyle changes, potential coronary artery bypass surgery
What is hyper-cholesterolaemia?
High blood cholesterol level
How does hyper-cholesterolaemia arise?
Genetic disposition
High saturated and trans fat diet
Lack of physical activity
Smoking
Obesity
Certain medical conditions - eg diabetes, hypothyroidism, kidney disease
How to manage hyper-cholesterolaemia?
Lifestyle modifications - eg low sat fat diet, more physical activity, quitting smoking
Medication - statins
What is the NHS guideline for physical activity?
150mins of moderate or 75 mins of vigorous physical activity a week
