Cardiology Flashcards
What is the cardiovascular system
The heart and blood vessel make up a blood transportation network response,e for delivering nutrients and oxygen to cells and waste products away from cells
Maintains constant internal environment - homeostasis
What are the two circulations of the CVS
Pulmonary: blood from right side of heart to lungs to left side of heart
Systemic: blood from left side of heart to capillary beds to right side of heart
What are the two functional parts of the CVS
Conducting: vasculature (tubes)
Exchange: capillary beds
What are the atrioventricular valves
Valve between atrium and corresponding ventricle
What are the valves in the heart
Tricuspid: RA -> RV
Pulmonary valve
Mitral (bicuspid): LA -> LV
Aortic valve
What is the role of the chord tendineae
Keeps the valves from inverting
What are the three parts of the aorta
Ascending
Arch
Descending
What branches of the arch of the aorta
Brachiocephalic trunk
Left common carotid artery
Left subclavian artery
What does the brachiocephalic trunk branch to form
Right common carotid artery
Right subclavian artery
What are the characteristics of the coronary circulation
They are the only branches which come from the ascending aorta
Two coronary arteries: left and right
RCA supplies main conducting centres of the heart
Functional end arteries so provide blood to specific areas of the lungs with little overlap
What arteries come from the coronary arteries
RCA: right marginal, posterior inter ventricular
LCA: Anterior interventricular, left marginal, circumflex
What would result from a blockage of coronary arteries
Reduced/indaquate blood supply
May lead to Ischaemia
Can lead to myocardial infarction
What are the three categories of arteries coming off the descending aorta
Ventral, unpaired arteries to GI tract
Paired, arteries to paired internal organs such as kidneys
Paired, segmental arteries to body wall such as intercostal arteries
What does the internal thoracic artery bifurcate into
Superior epigastric artery
Musculophrenic artery
At what level does the descending aorta bifurcate
L4
What vessels supply and drain from the limbs
Upper limbs: subclavian artery; subclavian veins
Lower limbs: external iliac artery; external iliac veins
What is the course of the lymphatic system
Lymphatic plexuses Lymphatic vessels Lymph nodes Thoracic duct or right lymphatic duct Venous system
What are the tube involved in the lymphatic system
Thin wall tubes which transport interstitial fluid, bacteria, cellular debris and whole cells
How is the lymphatic system involved in the spread of carcinomas
Lymphogenous
Patterns od lymph flow are important to predict or track back primary tumour
What makes up the body’s circulatory system
CVS and lymphatic system
What increases heart rate and decreases heart rate
Sympathetic system increases
Parasympathetic stem decreases
What is anatomy vs physiology
Physiology: function
Anatomy: structure
How does the vagus nerve act on heart
Parasympathetic
Like a brake
What is the sinoatrial node
Superior region of right atrium
Region where electrical impulses originate
Spontaneously depolarise
Dominant pacemaker cells
How do electrical impulses move through the heart
Start in SA node ->
Propagate through anterior, middle and posterior bundles -> depolarise across both left and right aria which is reflected -> delay at AV node to allow atria to fully contract -> Down through bundle of His which splits into left and right bundle and then into purkinje fibres -> propagates around the whole heart
What does the P wave reflect
Depolarisation from SA node through anterior, middle and posterior bundles, across the left and right atria
How do impulses spread quickly
Through gap junctions
What is the membrane threshold potential of pacemaker cells
-35 mV
What are the differences between pacemaker cells and non-pacemaker cells
Non-pacemaker resting potential is more negative: -90mV vs -70mV
NP influx mediated by sodium rather than calcium
NP has a plateau fase mediated by calcium
How is an electrical impulse interpreted from an ECG
Electrical activity TOWARDS an electrode gives POSITIVE deflection
Electrical activity AWAY from an electrode gives a NEGATIVE deflection
Where do the V1 to V6 chest leads look
V1 and V2 look at right
V3 and V4 look at ventricle septum
V5 and V6 look at left
What is the P-Q interval
AV node delay
What is the S-T segment
time between depolarisation and re-polarisation of the ventricles
What is the T wave showing
Ventricular re-polarisation
What is a sinus arrhythmia
Slowing go the SA node rate during expiration caused by an increase in vagal activity
tachycardia on inspiration
bradycardia on expiration
What is sinus bradycardia and what causes it
less the 60 beats per minute where mediated by only SA node
Athletic
Sleep
Medications
Hypothyroidism
What is sinus tachycardia and what causes it
More the 100 beats per minute where mediated by SA node only
Trauma Stress response Hyperthyroidism Infection Exercise Medication
What is ectopy
An extra heartbeat
How is complete heart block picked up on ECG
No association between P wave and QRS
What is atrial fibrillation
Electrical activity is irregular in atria
What is ventricular fibrillation
Electrical activity is irregular in ventricles
What is QRS complex
represents depolarisation of the ventricles
What is the PR interval
represents time take for electrical activity to move between atria and ventricles
How long does one cycle last
0.8 seconds
What is diastole
Filling of the heart ventricles
What is systole
Contraction of myocardium and ejection of blood
What is the stroke volume and what is the typical resting value
Volume of blood ejected from the left ventricle with each cardiac cycle
70ml
What is the cardiac output, what is the typical resting value and how is it calculated
Volume of blood ejected from the left ventricle each minute
5.0 l/min
Cardiac output = Heart rate x stroke volume
CO = HR x SV
When does formation of the heart begin
Week 3
What are the three layers of the heart and where does it derive from
Epicardium: visceral layer of the pericardium and derives from the visceral mesoderm
Myocardium: muscular wall; derived from the visceral mesoderm overlying the heart tube
Endocardium: internal endothelial lining of the heart; derived from the heart tube
What happens in vasculogenesis
Endoderm induces some cells of overlying visceral/splanchnic mesoderm to differentiate into angioblasts which further differentiate into endothelial cells and form tubes which are endocardial tubes
How is the primitive heart tube formed
Endocardial tubes fuse during lateral folding to form the primitive heart tube
How is myocardium made and what is it
The visceral mesoderm surrounding the primitive heart tube differentiates to form the myocardium which is the heart muscle and it secrets a thick layer of extracellular matrix which is cardiac jelly
What does the cranio-caudal folding cause for the heart
Brings the heart tube into the thorax
What are the five dilations of the heart tube
Truncus arteriosus (bulbous cordis) Conus arteriosus (bulbis cordis) Primitive Ventricle Primitive Atrium Sinus venosus
What happens on day 23
The heart tube begins to fold in preparation of forming the four chambers of the heart
Bulbus cordis: moves caudally, centrally and to the right
Primitive ventricle: displaced before moving back to midline
Primitive atrium: displaces cranially and dorsally
How are the ventricles formed
Majority of from primitive ventricle (trabeculated/rough)
and some from the conus arteriosus (smooth)
What does the right horn of the sinus venosus form
Sinus venarum (smooth part)
What landmark separated the smooth and rough parts of the atrial wall
Crista terminalis
Which layer of the heart tube forms the coronary arteries
Epicardium
What is intussusception and when does this happen
The 4 pulmonary veins are incorporated into the wall of the left atrium
Week 5
How is the primitive atrium separated and when does this happen
A crescent-shaped outgrowth from the dorsal wall forms called the septum primum and extends to diminish the connection between left and right sides
How is the atrioventricular septum formed
The endothelium lining the boundary between the atrium and ventricle expands to form dorsal and ventral endocardial cushion which fuse together to form the AV septum
How is the foramen secundum formed
Apoptosis occurs in the upper part of the septum premium to form a hole
What is the foramen ovale
An opening in the septum secundum which is formed at the same time as the foramen secundum
It allows the blood to flow from the right atrium to the left atrium, bypassing the lungs
How is the primitive ventricle separated and when does this happen
End of week 4
The muscular part that projects from the floor of the primitive ventricle towards the endocardial cushion leaving an inter-ventricular foramen
Week 7
A membranous part the projects inferiorly from eh endocardial cushion to close the inter-venticular foramen
What happens to the trunks arteriosus
Separation into aorta and pulmonary trunk
Divided into 2 channels by endocardial swellings (conotruncal ridges)
Swellings fuse to form a septum (conotruncal septum) that separates the outflow of left and right ventricles and fuses with the inter ventricular septum
The conotruncal swellings don’t fuse in a straight line but spiral around each other
What’s the difference in foetal circulation
Mother’s circulation is oxygenating and detoxifying blood therefore the foetal circulation shunts blood away from the lungs and liver
What is dextrocardia
Heart points towards the right side of chest instead of the left
May be a result of abnormal cardiac looping a=or induced during gastrulation (week 3)
What is patent ductus arteriosus
Ductus arteriousus doesn’t close at birth and so blood is shunted from aorta back into pulmonary trunk
What causes atrial septal defects
Failure of the septum premium and secundum to fuse after both
Malformations in the septum premum or secundumsuch that they do not overlap and therefore leave a gap
What is the premature closing of foramen ovale
Closure of foramen ovale during prenatal life
Results in hypertrophy of the right side of heart and underdevelopment of the left side
What is ventricular septal defect
Most common congenital heart defect
Often associated with the defects
Can affect the muscular or membranous part of the inter-ventricular septum
Defects in muscle often resolve as child ages
Allows left to right shunting blood
Can result in pulmonary hypertension and hypertrophy of right ventricle
What are the septation defects of the trunks arteriosus
Conotuncal swellings form the septum by migration of neural crest cells from the neural tube and so if they develop abnormally or migrate abnormally, defects occur
Persistant truncus arteriosus
Transposition of the great vessels
Tetralogy of Fallot
What is Tetrology of Fallot
A collection of four abnormalities with the same primary defect:
Pulmonary stenosis
Ventricular septal defect
Overriding aorta (rightward displacement of aorta)
Right ventricular hypertrophy caused by higher pressure of the right side
Leads to cyanosis: poor oxygenation of the body
What are the differences of white and red thrombus
White: contains lots of platelets, forms in fast flowing blood
Red: Contains lots of red blood cells, forms in slow flowing blood
What makes up a muscle
Each muscle is made up of muscle fibre and each muscle fibre is made up of myofibril
Myofibril contains thin filament (actin) and thick filament (myosin)
What is the cardiac functional reserve
Cardiac reserve refers to the difference between the rate at which the heart pumps blood and its maximum capacity for pumping blood at any given time
Cardiac reserve = maximal cardiac output - cardiac output at rest
What are the factors the influence myocardial contractility
Increase preload -> increased cardiac performance
Increase after load -> increased contractility
Increase heart rate -> increased contractility
Describe molecular biology of muscular contraction and energy generation
Tropomyosin and troponin work together to block binding sites on actin
When a calcium ion binds to troponin, the troponin-tropomyosin complex moves, exposing myosin binding sites
The chemical energy stored within ATP is converted into mechanical energy resulting in force generation and myofilament shortening
This transforms basic mechanical energy into useful hydraulic function for the whole organ
What are some clinical examples of myocardium decreasing resulting in less contraction
Ischemia: scarred myocardium less able to contract
Viral infection/ alcohol: wall thinning
How is mean systemic arterial blood pressure calculated
Cardiac output x Total peripheral resistance = Mean systemic arterial pressure
What increases the preload
Increase: circulating volume, Central venous pressure respiratory pump atrial filling or contraction
Decrease:
Venous compliance
heart rate
What is the Bainbridge reflex
Increased venous return
Baroreceptors in the atria detect increased stretch
Heart rate increased via sympathetic stimulation to SA node
Antagonistic to baroreceptor response
Involved in sinus arrhythmia
How does the sympathetic nervous system act on the heart
+ chronotropy: SA node to speed up to increase heart rate
+ dromotropy: Increase speed of conduction through AV node
+ inotropy: increases force of contraction in ventricles and atria
+ luisitropy: increased relaxation of ventricles and atria
What are the actions of the Renin angiotensin system
Angiotensin II: vasoconstriction
Increased Na+ and H2O retention
Aldosterone: increased Na+ and H2O retention
Vasopressin (antidiuretic hormone): promotes H2O retention
How does the parasympathetic nervous system act on the heart
- chronotropy: decreased heart rate
- dromotropy: decreased AV conduction
- inotropy: decreased atrial contractility
No effect on ventricles
What are the barareceptors
Located: carotid sinuses, aortic arch
Decrease arterial pressure: decreased firing
Increased arterial pressure- increased firing
Increased baroreceptor firing: decreases sympathetic tone and increases parasympathetic tone
AND THE REVERSE IS TRUE
What is blood pressure
Driving force propelling blood to tissues
Balance between organ perfusion and vascular damage
Closely auto-regulated
What is hypertension
BP control mechanisms are dysfunctional or are unable to compensate for stressors on the body
Defined as SBP >/= 140mmHg and/or DBP >/= 90mmHg
How is hypertension classified and what causes this
Primary: more common, age related or unknown
Secondary: specific cause: renal vascular disease, Cushing’s syndrome, coarctation of aorta, tumour, pregnancy
How can cardiac disease present
Stroke, TIA Heart failure Arrhythmia Angina MI Renal failure Aortic aneurysm Impotence (reproduction) Mesenteric ischemia/ infarction Peripheral vascular disease
How can hypertension be managed
Lifestyle changes
Medication: ace inhibitors (ramipril), Angiotensin II receptor antagonist (candesartan), Aldosterone blockers (Spironolactone) calcium channel blockers, diuretics, beta-blockers
What are some contraindications for hypertension medications
ACEi -> pregnancy
B blockers -> asthma
Diuretics -> hypokalaemia, gout
What is the preload
The level of stretch that a cardiomyocyte is exposed to before ventricular ejection
What is the afterload
The pressure against which the heart is contracting when it ejects blood
What is Starling’s law of the heart
The law of the heart is thus the same as the law of muscular tissue in general, that the energy of contraction, however measured, is a function of the length of the muscle fibre
What is aldosterone
Mineralcorticoid
From adrenal cortex
Released in response to Angiotensin II
Renal tubular effects
How does aldosterone work
Acts on DCT and collecting duct
Internalised and binds to intracellular aldosterone receptor
Increases transcription of gene for epithelial Na+ channels
Augments reabsorption of Na+ and H2O
Excretes K+
Increases Angiotensin II receptors
What happens in heart failure
Back pressure in LV causes raised pressure in pulmonary circulation
Increased hydrostatic pressure forces fluid outside vascular compartment
Interstitial space in lungs fills with fluid
Pulmonary oedema/ pleural effusions
What would be the acute therapy in heart failure
Resuscitation Airways, Breathing, Circulation (ABC) Oxygen Optimise alveolar ventilation Increase pressure in airways to oxygenate blood Non-invasive or invasive ventilation
Why is morphine given to patients with heart failure
Pain management
Relax pulmonary vessels
Reduce her preload and take stain off the LV
Help with her breathing
What do diuretics do in patients with heart failure and what are the side effects
Limit reabsorption of fluid
Offloads the ventricles
Moves back along the Starling curve
Can maximise LV contractility
Side effects:
Renal dysfunction
Reduces Na, K, Mg
Can induce diabetes
How do beta-receptors work
Involved in myocardial and renal responses to reduce cardiac output
How do beta-blockers work in patients with heart failure and what are the potential side effects
Block beta-receptors resulting in decreased heart rate
Moves back along the Bowditch curve
Allows LV more relaxation time, soberer filling
Also blunts RAAS over-activation
Side effects: asthma, low HR, heart blocks
What is the main energy supply of the heart
Fat as it can burn more ATP per gram but can in theory burn anything
What are the characteristics of capillaries
Single layer of endothelial cells 5- 10uM in diameter 0.5-1 mm in length Blood cell velocity approx 0.3-1mm/sec Short distance between capillary and cell it serves Junctions between capillary cells normally tight but very tight in CNS, and large clefts between cells in liver and bone marrow A large network Large surface area
What are the three types of capillaries
Continuous capillary: fat, muscle, nervous system
Fenestrated capillary: intestinal villi, endocrine glands, kidney glomeruli
Discontinuous capillary: liver, bone marrow, spleen
What is an oedema
An increase in volume of the interstitial fluid above normal
What is a stroke
The rapidly developing loss of brain function due to disturbances in the blood supply to the brain
What is cerebral haemorrhage and how is it prevented
Rupture of a blood vessel can produce a bleeding type of a stroke when an aneurysm of a blood vessel in the brain ruptures
By controlling blood pressure
What is cerebral ischaemia
Blockage of blood vessel
May be due to thrombus or embolus
What is a transient ischaemic attack
A mini stroke
Result of temporary disruption of the circulation to the part of the brain due to embolism or thrombosis to brain arteries
What are the symptoms of a stroke
Localised abnormalities of the nervous system:
Weakness in arm or leg
Slurring of speech
Drooping corner of mouth
Difficulty swallowing
Inability to find the right words to say or lack of understanding of words
What investigations can be done in stroke patients
Brain CT
Ultrasound of carotid artery
Echocardiogram
ECG
What is angina
Pain in the centre of the chest that may spread to the jaw and arms
Induced by exercise and relieved by rest
Occurs when the demand for blood by the heart exceeds the supply of the coronary arteries
Usually results from coronary artery atheroma
What happens during a heart attack
Most heart attacks are caused by coronary artery disease where the arteries narrow due to a gradual build-up of artheroma within their walls
If the atheroma becomes unstable, a piece may break off and lead to blood clot forming which can block the coronary artery starving the heart of blood and oxygen causing damage to the heart muscle which is the heart attack
What are the other names for a heart attack
Acute coronary syndrome
Myocardial infarction
Coronary thrombosis
What are the treatment options for aortic stenosis
Aortic valve replacement
What is myocarditis and what causes it
Inflammation of the heart muscle
Infection, immunological causes, drugs and toxins, viral causes
What are the symptoms of systolic heart failure
Shortness of breath Swelling of feet and legs Chronic lack of energy Difficulty sleeping due to Breathing problems Swollen or tender abdomen with loss of appetite Cough with frothy sputum Increased urination at night Confusion and/or impaired memory
What is a cardiac synacope
The medical term for fainting, a sudden, usually temporary, loss of consciousness generally
