Cardiac Lectures Flashcards
What is the outermost layer of the heart?
Pericardium
What are the two layers of the pericardium?
Fibrous pericardium and serous pericardium
What is the function of the fibrous pericardium?
- Forms protective outer layer
- Anchors heart to diaphragm / mediastinum
What are the layers of the serous pericardium?
- Inner visceral layer (epicardium)
- Outer parietal layer (fused to fibrous pericardium)
What is the potential space between serous pericardial layers called?
Pericardial cavity (lubricant, NOT air)
What is the mitral valve?
The bicuspid valve between the left ventricle and atrium
What is the fibrous skeleton of the heart?
The collagenous rings that surround the atrio-ventricular canals and extend to the origins of the aorta and pulmonary trunks
What is the purpose of the fibrous skeleton of the heart? (3 reasons)
- Provides an insulating barrier between the atria and
ventricles - Anchors the valve cusps (leaflets) to prevent dilation
of valves - Provides attachment for spirals of myocardium that
extend towards the apex
What is the purpose of chordae tendineae and papillary muscles?
Prevents inversion of the valves into the atria
How many cusps do semi-lunar valves have?
3
What is a valve stenosis?
Valve not opening fully
What is valve regurgitation?
Valves leaking
What is endocarditis?
Infection or vegetation on the valves
What valve is seen in the ‘fish eye’ echo view?
Mitral valve
Which coronary arteries can you see from an anterior view of the heart?
Left anterior descending and right
Describe anatomically how the aorta leaves the heart
The aorta leaves the base of the heart and loops posteriorly and to the left behind the heart
Which coronary arteries can you see from the posterior view of the heart?
The end of the right coronary artery and the circumflex artery (these join)
- you can also see the coronary sinus
What structures can you see from the posterior view of the heart?
Mainly the left ventricle, right and left atrium, pulmonary arteries and veins, vena cava, aorta and coronary sinus
What is the coronary sinus?
The major coronary veins, on the posterior side of the heart, located just above the circumflex artery
Drains blood directly to the right atrium
How is the pulmonary artery related to the pulmonary veins from posterior view?
The pulmonary artery is above the pulmonary veins (between veins and aorta)
What proportion of the myocardium do the epicardial arteries supply?
The outer 2/3rds
When does most of cardiac perfusion occur?
Diastole, as contraction of cardiomyocytes during systole causes extravascular compression of the arteries
Tachycardia can be concerning
What 3 conditions are under the umbrella term Acute Coronary Syndrome (ACS)?
- Unstable angina
- Non st-elevation MI
- ST-elevation MI
What are the 3 types of angina?
- Stable
- Unstable
- Prinzmetal (variant angina)
What is the difference between stable and unstable angina?
Stable has triggers e.g. exercise or stress and usually stops when resting - caused by fixed atherosclerotic build up
Unstable is unpredictable and can occur at rest
What structures allow cardiocyte contraction?
Myofibrils contract to shorten the sarcomere
What is the name for the site that joins adjacent cardiomyocytes?
Intercalated disks
How do action potentials transfer from cell to cell in the myocardium?
Through gap junctions and intercalated disks
What is cardiac amyloidosis? And what can it cause?
Amyloid deposits take the place of cardiomyocytes - causes restrictive heart disease
What is Frank-Starking law? And what proportion of blood in the ventricles is ejected each contraction?
The heart pumps what it recieves (roughly 2/3rds of the blood in each ventricle each contraction)
Explain the heart sounds
Lub - sound of AV valves closing (start of systole)
Dup - sound of semi-lunar valves closing (end of systole)
What are the 4 different stages of the cardiac cycle?
- Isovolumetric contraction
- Ventricular Ejection
- Isovolumetric relaxation
- Ventricular filling
Explain ventricular filling
- Rapid passive diastolic filling
- Atria contract
- Mitral (and tricuspid) valves close
Coincides with P-wave
Explain isovolumetric contration
Is the QRS of the ECG, LV starts to contract, all valves are closed
What is ventricular pre-excitation? And what is it caused by?
Early excitation and contraction of the ventricles due to accessory pathways
What is long QT syndrome? And what can it predispose?
QT > 450 ms (greater than 2.1 large squares)
(start of Q to end of T)
It can predispose to ventricular arrhythmias
What is a normal QT interval?
350 - 450 ms
How many large ECG squares make up 1 second?
5 squares (each square is 200ms)
What is JVP and why is it useful?
Jugular venous pressure - provides an indication of central venous pressure
What does a raised JVP indicate? And what cardiac causes can elevate JVP?
Venous hypertension. Cardiac causes of this include:
1. Right sided heart failure (can often result from COPD or restrictive lung diseases)
2. Tricuspid regurgitation (caused by endocarditis)
3. Constrictive pericarditis
What can fine bibasilar crackles indicate?
Fluid or mucus build-up in the lungs
What does the bundle of His divide into?
Left and right bundle branches
What does the left bundle branch divide into?
Anterior and posterior fascicle
- anterior goes into LV muscle anteriorly
- posterior goes down the wall into the apex
Where do the purkinje fibres originate from?
The anterior fascicle and the right bundle branch
Define a P wave?
The first deflection of the cardiac cycle. Caused by the atrial contraction
Define Q
Q is the first negative deflection below the isoelectric baseline
Define T waves?
The signal from ventricular repolarisation. Can be negative or positive
What is the U wave? And what is a proposed source
A second deflection following the T wave, usually in the same direction. Its source is unknown, but could be due to delayed purkinje repolarisation
What is the J point?
Is the junction between QRS and T wave. Is found on all ECGs.
There are many causes of J point deviation from baseline (pathological and not)
What is the J wave (Osbourne wave) indicative of?
Hypothermia
What is the ST-segment?
The time between the J point and the start of the T wave. i.e. the time between ventricular depolarisation and repolarisation
- it should be around 0.08 ms
How long is a normal ST segment?
80 - 120 ms
Which leads indicate lateral ischemia?
I, aVL, V5, V6
Which leads indicate septal ischemia?
V1-2
Which leads indicate anterior ischemia?
V3-4
Which leads indicate inferior ischemia?
II, III, aVF
How is coronary vasospasm detected on ECG?
Very similar to acute STEMI, however is transient
What is the difference between segments and intervals?
Segments are usually end-start
Intervals are usually end-end of features
How do you determine heart rate on ECG if regular?
300 / number of large spaces between QRS complexes
How do you calculate HR from ECG if irregular?
Number of complexes in 6 seconds (30 large squares) X 10
What is the standard calibration of an ECG?
10mm (10 small squares) = 1mV
25mm/second
What are the colours of standard 4 electrode ECG?
Right arm = red
Left arm = yellow
Left ankle = green
Right ankle = black
These are the same for the 12-lead ECG as well
Where are V1 and V2 positioned?
4th intercostal space, either side of the sternum
What does right or left arm reversal do to the ECG?
It completely inverts it
What is the maximum value for PR interval?
120 - 200 ms (one large square)
PR interval should be constant
What is the PR interval?
From the start of the P wave to the start of the QRS (Q)
What is usually the lowest bpm in bradycardia?
40 bpm
(If lower, consider heart block)
How does inspiration and expiration impact HR?
Inspiration increases HR
Expiration decreases HR
What is sinus arrhythmia?
Regularly irregular heart rate - can be caused by breathing
(uncommon after the age of 40)
What is the difference between atrial fibrillation and atrial flutter?
QRS complexes are usually regular in flutter. Saw-tooth flutter waves are seen.
What is ventricular tachycardia? And how does it appear on ECG
Broad QRS complex, HR > 120 bpm, independent P waves. Usually >3 beats (this would be ventricular ectopics)
How long does each of the 12 ECG leads show? And how long does the rhythm strip show?
Each lead shows 2.5 seconds and the rhythm strip shows 10s
What is a normal PR interval?
3 - 5 small squares (120 - 200ms)
Describe first degree heart block?
Long PR interval >200ms
(Q comes home late)
Describe 2nd degree Wenkebach (Mobiz 1) heart block?
PR interval gets progressively longer, then skips a QRS, then comes early
Describe Mobiz type 2 heart block
PR stays the same but the heart irregularly skips beats
What is 3rd degree heart block?
P and QRS are completely independent
What is ventricular pre-excitation?
Wide QRS with delta wave, short PR interval, secondary T wave changes
What causes ventricular pre-excitation?
Accessory pathways (e.g. Wolf-parkinson white syndrome)
How do statins lower cholesterol?
Block conversion of acetate to cholesterol
What are 3 main types of cholesterol lowering drugs?
Statins, PCSK9 and Ezetimibe (less common)
Name some common blood pressure medications?
- Ca channel blockers
- ACE inhibitors
- Angiotensin-2 blockers
- diuretics
- beta blockers
What is ‘bad cholesterol’?
Low density lipoprotein (LDL)
Are pulses present in capillaries?
No
What is systolic pressure?
The pressure created by the heart as it pumps
What is diastolic pressure?
The pressure remaining in the vessels during cardiac relaxation
What is pulse pressure?
The difference in systolic and diastolic pressure
What is the usual ratio of Sys BP : Diast BP : PP?
3 : 2 : 1
What is mean arterial pressure?
Arterial pressure averaged over time
Is mean arterial pressure closer to systolic or diastolic pressure?
Diastolic pressure - twice as long is spent in diastole than systole
How much lower are female BPs than male on average?
Around 8 - 10 mmHg
Where should the stethoscope be placed for taking manual blood pressure?
Brachial artery at the Antecubital fossa (inside elbow)
What is a K1 Korotkov sound?
Faint repetitive tapping, artery is just open = systolic pressure
What is a K5 Korotkov sound?
No sound, laminar flow = diastolic pressure
What do you do if K5 goes to zero?
Use K4 (muffling of sounds)
What percentage of adults does hypertension affect?
1 in 4 (25%). Is 3rd biggest risk of premature death in the UK after smoking and diet
What is stage 1 hypertension?
Clinic BP > 140/90 mmHg
What is stage 2 hypertension?
Clinic BP > 160/100 mmHg
What is severe hypertension?
Clinic systolic BP > 180 or diastolic pressure > 120 mmHg
How often should BP be taken in ambulatory BP measurements?
At least twice per hour in the persons usual waking hours
An average of at least 14 measurements should confirm BP
How often should home blood pressure monitoring be measured?
–two consecutive seated measurements, at least 1 minute apart
–blood pressure is recorded twice a day for at least 4 days and
preferably for a week
–measurements on the first day are discarded –
average value of all remaining is used.
How should patients be positioned for BP?
Cuff at level of heart, arm supported
What is the ischaemic cascade?
Hypoperfusion -> cellular metabolic changes -> Diastolic dysfunction -> systolic dysfunction -> ECG changes -> chest pain
What is the doppler equation?
fo = ((v + vo) / (v + vs)) fo
fo = frequency observed
v = speed of sound (1540m/s)
vs = source velocity
vo = velocity observed
What are the 5 echo windows?
Suprasternal, left and right parasternal, apical and subcostal
What are the 2 aspects used when naming echo images?
- Acoustic plane
- View (Long axis, short axis, 4 chamber, 2 chamber, 5 chamber)
What orientation is long axis?
Slices from base to apex of the heart
What orientation is short axis?
Slices roughly parallel to AV line
What is congestive heart failure?
Inability of heart to meet metabolic demands.
Characterised by reduced cardiac output.
Usually occurs if the heart becomes too weak or stiff.
What are some clinical symptoms of congestive heart failure?
Dypsnoea, oedema, fatigue and poor exercise tolerance
Name the pathophysiological changes following MI that lead to CHF?
MI -> reduced heart function -> period of stabilization -> terminal decline
Why does the heart fail several years after MI?
Is a cycle.
LV dysfunction causes LV remodelling and neurohormonal stimulation. This increases LV dysfunction directly and secondary to increased peripheral resistance
Name some of the many aspects of neurohormonal activity that is increased in CHF
Plasma renin, plasma neurepinephrine, ANP, endothelin-1
What are the acute and chronic effects of neurohormonal stimulation in CHF?
Acute: Increases blood pressure, preserves perfusion to organs
Chronic: Increased afterload, reduced stroke volume, myocyte necrosis and apoptosis, sodium retention
What electrolyte is retained as result of CHF neurostimulation?
Sodium
What is cardiac afterload?
The pressure at which the heart must overcome to eject blood during systole
(Is directly proportional to MAP)
How is plasma neuradrenaline associated with mortality in CHF?
Increased neuradrenaline is associated with increased mortality rates in CHF
How does neurohormonal activity impact heart structure in CHF?
The heart becomes dilated and larger
What is ejection fraction equal to?
Stroke volume / end-diastolic volume
What are some of the causes (aetiology) of CHF?
MI, hypertension, valvular heart disease, idiopathic dilated cardiomyopathy, secondary cardiomyopathy (alcohol, anthracyclines), myocarditis
What is anthracycline cardiomyopathy?
Cardiomyopathy as result of free radicals from doxorubicin
What is myocarditis?
Inflammation of myocardium
What symptoms can myocarditis cause?
Chest pain, SOB, heart arrhythmias
What is the S1 heart sound?
The first sound caused by the closing of the mitral and tricuspid valves
What is the S2 heart sound?
The second heart sound caused by the closing of the aortic and pulmonary valves
How does inspiration change the S2 sound?
It splits S2, with the pulmonary valve shutting after the aortic - normally they occur almost at the same time
What causes the heart sounds S3 and S4?
S3 and S4 are caused by blood striking the LV walls - usually because they are dilated
What are some signs and symptoms of left sided heart failure?
S3 and S4 heart sounds
Dsypnoea
Orthopnoea (breathlessness lying)
Cough
Chest crackles
S3 and S4 sounds
What are some signs and symptoms of right sided heart failure?
Abdominal distension and loss of appetite
Elevated JVP
Hepatomegaly
Peripheral oedema
What is hepatomegaly?
Enlarged liver
What are treatments for acute heart failure?
Sit patient up (reduces LA pressure)
Give oxygen, morphine, sublingual nitroglycerin
Check cardiac rhythm
IV loop diuretic
How does sitting up treat acute heart failure?
It decreases LA pressure
What are medical treatments of chronic heart failure?
Maintain oedema free
Fluid and salt restriction
Inhibition of RAS or neurohormonal stimulation
- Causes negative chronotropic and ionotropic effects
How do beta blockers impact cardiac function?
They block the release of renin, neuradrenaline and adrenaline
- improves the heart’s ability to relax
- reduce risk of sudden cardiac death
What are some common medications to treat hypertension and CHF?
ACE inhibitors, beta blockers, angiotensin receptor blockers (ARBs), aldosterone inhibitors
How do ACE inhibitors work?
Inhibit angiotensin converting enzyme activity
What are some of the difficulties of treating heart failure?
Most treatments reduce blood pressure - you can only reduce BP so much
Multiple medications are complex for both patients and doctors
Electrolytes and renal function must be closely monitored
What is diastolic heart failure?
Heart failure with preserved ejection fraction.
LV systolic function is maintained.
Is problem with LV relaxation.
Is often associated with comorbidities e.g. diabetes, age, renal dysfunction, hypertension
What are the main causes of sudden cardiac death?
Ventricular tachycardia / fibrillation
Which medications reduce risk of sudden cardiac death?
Beta blockers -> increase ability of heart to relax
- implantable cardiodefibrillators also reduce death
What are mortality rates of heart failure patients?
Around 33%
What is a typical dose of ionising radiation from a chest X-ray?
0.06 mSv (micro Sievert)
Which structures can be seen on a chest X-ray?
Heart, lungs, aorta, pulmonary vessels, bones, soft tissue, diaphragm, liver, gastric air
What are the ABCDEFs of chest X-rays?
Airways
Breast shadows
Bones
Cardiac silhouette
Costophrenic angles
Diaphragm
Edges
Extrathoracic tissues
Fields
Failure
What is the costophrenic angle?
The angle where the diaphragm meets the ribs.
Sharply-pointed downwards angle
What are some common reasons for ordering a chest X-ray?
Pleural effusion
Pneumothorax
Haemothorax (blood in pleural space)
Pulmonary Embolism
Trauma
TB
Monitoring chest drainage
Lung cancer
Chest pain (MI)
COPD
Asthma
What is a pleural effusion?
Build up of fluid in the pleural space
What are cardiac reasons for ordering a chest X-ray?
Cardiomegaly
Wide mediastinum
Heart failure
Pleural effusion
What is the mediastinum?
The space within the thorax that contains the heart and other structures
Why do lung fields appear dark?
Due to presence of air in the lungs
How can you identify lung disease on CXR?
Most disease replace air with liquid - appears white
Are chest X-rays usually taken in AP or PA?
Usually PA
- anterior structures are closer to detector
- reduces size of cardiac silhouette
What is the cardiothoracic ratio?
Ratio of transverse diameter of the heart to the internal diameter of the chest at its widest point, just above the dome of the diaphragm
What is increased cardiac silhouette usually caused by?
Cardiomegaly (but can also be caused by pericardial effusion)
What are the 3 stages of CHF seen on X-ray?
- Redistribution - increased pulmonary markings, cardiomegaly
- Interstitial oedema
- Alveolar oedema
What is aspirin prescribed for?
Anti-inflammation drug, also used as an antithrombotic (antiplatelet)
What is amlodipine?
Calcium channel blocker used to treat hypertension and coronary artery disease
What are the reporting guidelines for the ambulatory ECG?
There currently are not guidelines
What are the two fundamental functions of pacemakers?
- Pace
- Sense
What does a pacemaker pulse generator contain?
Battery, capacitor, telemetry coil, connector for leads
What do pacemaker leads comprise?
Electrodes, conductor, insulation, connector, fixation mechanism
What is a pacemaker threshold?
The minimum amount of electrical energy required for the pacemaker to cause cardiac muscle depolarisation
What is capture of the heart?
The myocardial response to electrical stimulation
What is the 3 letter pacemaker code?
- Paced - A, V or D (dual)
- Sensed - V, A, D or 0 (none)
- Mode of response:
- T = triggered, I = inhibited, D = dual, 0 = none
What is CRT?
Cardiac resynchronisation therapy
What is PBL-STOP in pacemakers?
Presenting rhythm
Battery status
Lead status
Sensing
Threshold
Observation, Data and Events
Programme and print
How can filters impact ECGs?
They can remove pacing spikes
Which side of the heart do most of the vessels come out of?
Posterior side
What is WPW syndrome?
Presence of congenital accessory pathways and episodes of tachyarrhythmias
What is the RAAS system and how does it impact the heart?
Renin angiotensin aldosterone system
- acts to help retain salt and water
- increases PVR and can worsen heart failure
What is the first choice medication for treating AF?
Beta-blockers or calcium channel blockers (help increase cardiac relaxation)
What is the heart rate range for newborns?
110 - 150 bpm
At what ages does a child’s heart rate become similar to adults?
6 +
What is the heart rate range for a typical 2 year old?
85 - 125 bpm
What is the heart rate range for a typical 4 year old?
75 - 115 bpm
What are the 3 types of narrow complex QRS?
Sinus, atrial or junctional
What are the two types of wide QRS complex?
Ventricular and supraventricular with aberrant conduction
What are vagal manoeuvres?
An action used to stimulate the parasympathetic nervous system e.g. valsalva manoeuvre, cough etc.
What is AVRT?
Atrioventricular re-entrant tachycardia. Involves an accessory pathway either orthodromic (anterograde) or antidromic (retrograde)
What are the colours and positions of the 3 electrode ECG?
White - right shoulder (2nd intercostal space)
Black - left shoulder (2nd intercostal space)
Red - left 9th rib
What are the colours and positions of the 5 electrode ECG?
White - right shoulder (2nd intercostal space)
Black - left shoulder (2nd intercostal space)
Red - left 9th rib
Green - right 9th rib
Brown - right 4th intercostal (v1)
Where is V4 located?
5th intercostal space, mid-clavicular line
Where is V5 located?
5th intercostal space, anterior auxillary line
Where are V7 - 9 placed?
Posterior chest wall, same level as V6
What are the colours and positions of the 4 electrode ECG?
Red
Yellow
Green
Black
What colours are chest leads V1-6?
Red
Yellow
Green
Orange
Black
Purple
What are common ECG presentations of V1 - V2 misplacement?
P wave changes, Incomplete RBBB
(also false STEMI, Brugada’s syndrome and T-wave inversion)
What is Brugada syndrome?
An ECG abnormality with a high incidence of sudden death in patients with structurally normal hearts.
A sodium channelopathy
What are common ECG features of WPW syndrome?
Delta wave
Short PR interval (<120ms)
ST and T wave changes
Long QRS
- caused by accessory pathways and tachyarrhythmias
What is the immediate clinical management of a patient with haemodynamically unstable AF?
DCCV if acute AF and anticoagulants (e.g. warfarin, heparin, DOACs)
Should AV nodal blocker drugs be used for accessory pathway patients with AF?
NO:
Conduction through the AV node actually helps to slow AP conduction - AVN has longer refractory period than APs
What 2 forms of tachycardia are present in WPW patients?
- Atrial fibrillation or flutter that can bypass the AVN via AP
- Atrioventricular re-entrant tachycardia
what is the most common form of VT?
Monomorphic VT
- regular, broad complex tachycardia
What is the clinical significance of VT?
Impaired cardiac output - consequently hypotension, collapse and acute heart failure
- caused by extreme heart rates and reduced atrial coordination (‘kick’)
What are the 3 factors when classifying VT?
- Clinical presentation - haemodynamically stable / unstable
- Duration - sustained >30s or non-sustained
- Morphology - monomorphic, polymorphic, TDP, bidirectional, ventricular flutter
What is Toutes De Pointes?
A pattern of VT similar to the double helix - twist
QT prolongation
What are the 3 mechanisms of VT?
- Reentrant (commonest)
- Triggered activity VT
- Abnormal automaticity
What are some key ECG features of AF?
Irregularly irregular, no P waves, no isoelectric baseline, QRS usually <120ms (unless BBB)
- note fibrillation may mimic P waves
What are 2 proposed mechanisms for AF?
Focal activation - often pulmonary veins
Multiple wavelet mechanism - fibrillation is formed by re-entrant circuits
- process is potentiated with dilated LA
What is AF with slow ventricular response?
Ventricular rate <60bpm (is less common than AF with fast response)
What is atrial flutter?
- Narrow complex tachycardia (like AF)
- Regular atrial activity at 300bpm
- Loss of isoelectric baseline (like AF)
- “saw tooth” pattern of inverted flutter waves in leads II, III aVF
- Upright flutter waves in V1 that may resemble P waves
May have variable or non-variable AV conduction ratio
What causes atrial flutter?
Supraventricular tachycardia caused by a re-entry circuit within the right atrium
- length of re-entrant circuit corresponds to the size of the right atrium - predictable rate of ~300bpm
What is the most common AV conduction ratio in flutter?
2 : 1 - leads to ventricular rate of 150bpm
What are the different forms of re-entrant circuits in atrial flutter?
Anticlockwise re-entry (90%)
Clockwise re-entry (10%)
How can anti-clockwise and clockwise atrial flutter be distinguished on the ECG?
Anti-clockwise has inverted flutter waves in leads II, III aVF and upright flutter waves in V1 that may resemble P waves
Clockwise is the opposite
What is AVNRT?
Atrioventricular Nodal Re-entrant Tachycardia
How can you distinguish atrial flutter from AVRT or AVNRT?
Flutter nearly always has a rate of around 150 bpm
AVRT and AVNRT are faster (170 - 250 bpm)
How can vagal manoeuvres or adenosine impact AVNRT?
AVRT or AVNRT can often return back to sinus rhythm
- be careful with AVNRT as AVN acts as a brake on accessory pathway (longer refractory period)
How can vagal manoeuvres or adenosine impact sinus tachycardia and atrial flutter?
It slows the ventricular rate
How can Brugada syndrome be identified on ECG?
McDonalds M in >1 of V1 - 3
What are common ECG features of WPW syndrome?
Delta wave present (curved QRS) and T wave changes - often inverted
What direction do most APs travel?
Both ways
What are some of the causes of low voltage QRS?
- Obesity
- Fluid around heart (pericardial or pleural effusion)
- Air - emphysema or pneumothorax
- Infiltrative / connective tissue disorders
- Loss of viable myocardium (dilation, previous massive MI)
What is diaphoresis?
Excessive sweating due to underlying health conditions
What is pericardial tamponade? And how may it present on ECG
Compression of the heart by the pericardial fluid. Can cause low voltage ECG and sinus tachycardia
What gives the lungs a ‘lacy’ appearance on chest X-ray?
Pulmonary vasculature
ST elevation in which ECG leads is indicative of Right coronary artery stenosis/occlusion?
II, III, aVF
Which coronary arteries are likely to be stenosed / occluded in lateral lead ischemia?
LAD and left circumflex artery
Which coronary artery is likely occluded if anterolateral ECG leads show STEMI?
Left anterior descending
What is the clinical impact of using a blood pressure cuff that is too small?
It falsely elevates BP measurements
What is the clinical impact of using a blood pressure cuff that is too big?
It falsely lowers BP measurements
Which spinal nerves can increase ionotropy and chronotopy through the sympathetic NS?
T1 - 4
What are negative chronotropes and some examples?
Decrease heart rate
- Beta-blockers and calcium channel blockers
What are negative ionotropes and some examples?
Decrease heart force of contractility
- beta blockers and calcium channel blockers
(also some anti-arrhythmic drugs e.g. flecainide and disopyramide)
What are positive ionotropes and some examples?
Increase heart force of contractility
- dopamine and dobutamine
What are positive chronotropes and some examples?
Increase heart rate
- e.g. dopamine and dobutamine
Which part of the ECG represents isovolumetric contraction?
The QRS
Which part of the ECG represents ejection?
QRS to 3/4 of T wave
Which part of the ECG represents isovolumetric relaxation?
last 1/4 of T wave
On which side of the body does lead III point towards?
The lower right
Which coronary arteries can cause inferior STEMI?
Any of the 3 main coronary arteries
- RCA in 80% of cases
- LCx in 18%
- LAD rare
What does the ST segment represent and how long should it be?
The refractory period and should be 80ms (2 squares)
How is dextrocardia identified on ECG?
P wave inversion in lead I and poor P wave progression in the chest leads
Why is lead II commonly selected as the rhythm strip?
It shows P wave activity the clearest
What is aberrant conduction?
When the impulse cannot properly travel through the His-purkinje fibre system
- shows as a broad QRS complex
What determines the dominance of the coronary arteries?
And what is the most common dominance?
Which artery feeds the posterior descending artery
- Right dominance occurs in 90% of cases
Which coronary arteries supply the SA node?
RCA (60%)
LCx (40%)
If ST elevation is seen in leads II, III and aVF, which coronary artery is likely occluded?
RCA (90%)
LCx (10%)
What are the default filter settings for ECGs?
0.05 - 150 Hz
- displayed at bottom right of ECG
However all filters should initially be turned off
- this detects from 0.67 - 150Hz
What is the maximum filter setting that should be applied?
0.67 - 45Hz
Describe the layers of the heart from inner to outer
Endocardium -> myocardium -> visceral pericardium -> pericardial cavity -> parietal pericardium
Is the LV wall thicker at the base or apex?
Is thicker at the base
What is the bulk of the myocardium composed of?
Cardiomyocytes
What are the dimensions of cardiomyocytes?
Length = 120um
Width = 20 - 30 um
What surrounds each cardiomyocyte?
The network of interstitial connective tissue
What is the perimysium?
The thick connective tissue weave between cardiomyocytes that bears shear forces and prevents misalignment
What are the 3 layers of the left ventricle wall according to longitudinal alignment of myocardial strand?
Superficial (subepicardial)
Middle
Deep (subendocardial)
- not anatomically separated - just different arrangements of myocardial strands
What are the two weaves that provide connective support to myocytes?
Endomysial weave (thin) - coordinates force and prevents slippage
Perimysium weave (thick) - bears shear force and prevents misalignment
What is the heart crux?
The cross shape formed by the intersection of the planes of the atrial and ventricular septa upon the inferior AV junction
How are the left and right AV junctions anatomically related?
Right AV junction is inferior to the left
What does cephalad mean?
Towards the head (or anterior extremity of the body)
What are the 3 basic components of the ventricles?
- Inlet
- Apical trabecular
- Outlet
How many groups of papillary muscles support the mitral and tricuspid valves?
Only 2 support the mitral.
A variable number support the tricuspid
How are the superficial subepicardial fibres and deep myofibres arranged?
Deep are longitudinal (apex - base)
Superficial are circumferential
What can sometimes limit the views of the RV using echo?
The RV is located directly behind the sternum
- RV also has very thin walls
What are heart trabeculations?
Bundles of muscle that extend into the chamber
Describe the structures seen in a parasternal long axis echo view?
The LV is seen at the top of the screen with the LV and LVOT below and some of the LA and AO origin
Where is the coronary sinus located?
In the left atrioventricular groove
What are the 3 basic parts of the right atrium?
- The appendage
- The venous part
- The vestibule
(note is also the septum)
What is the terminal groove?
A fat-filled groove where the SA node is located
What is the Eustachian valve?
The valve between the Vena Cava and the right atrium
How does the coronary sinus drain?
Into the right atrium through the Thebesian valve
Which cardiac disease is rheumatic fever as a child a risk factor for?
Mitral valve stenosis
Do patients with heart valve replacements need to take blood thinning drugs?
Not if prosthetic valves are used
However they do if they have mechanical replacement valves
Stenosis in which coronary artery is most likely for an antero-septal STEMI?
LAD
How is stable angina detected on ECG?
ST depression
- is associated with chest pain on exertion
Why is exercise ECG not used for stable angina diagnosis? And what are the specificities and sensitivities of it
There are better methods available (e.g. dobutamine stress echo)
- sensitivity = 70%
- specificity = 80%
What are the specificities and sensitivities of dobutamine stress echo?
Sensitivity = 85%
Specificity = 95%
What is treatment of choice for coronary artery stenoses?
Percutaneous coronary intervention (PCI)
- or CABG in extreme cases
How is NSTEMI detected on ECG?
Either ST-depression or T wave inversion
What are key features of myocytes?
- Lots of Myoglobin
- Branching structure
- Mostly single, central nucleus
- Many mitochondria
- Myofibrils to contract
- Cell-cell contact at intercalated disks
What are common thrombolytic drugs?
Streptokinase and urokinase
Which vertebrae is the superior mediastinum at the level of?
T1 - T4
What does the superior mediastinum contain?
The great vessels
What is the inferior mediastinum divided into?
Anterior, middle and posterior mediastinum
How are the left and right pulmonary veins related to each other as they enter the right atrium?
Left are above the right
How is the base of the heart anatomically located?
Posteriorly compared to the apex and at the level of T6-9
What is the level of the aortic arch?
T4
What is the PR interval?
From the start of the P wave to the start of the QRS complex (not until R)
- should be 0.12 - 0.2 seconds
What is sinus bradycardia?
Less than 60 bpm
How do atherosclerotic plaques form?
- Monocytes enter the vessel wall through the endothelial layer
- Monocytes transform into macrophages
- Macrophages combine with OxLDL to form foam cells
- Smooth muscle cells and foam cells migrate and proliferate
- This forms the plaque
What are the 3 classes of drugs that help to lower cholesterol?
- Statins - stop conversion of acetate to cholesterol
- PCSK5 inhibitors - stop LDL transport into cell
- Ezetimibe - Reduces GI absorption
What is orthopnoea?
Breathlessness when lying down, relieved by sitting
How do ARBs and ACE inhibitors treat heart failure?
They decrease salt retention
How can heart conditions make echo imaging difficult?
They can move the apex of the heart
What is the most likely heart condition if the patient has a raised BNP?
Congenstive heart failure
What is a normal ejection fraction?
50% to 70%
What is a low EF?
40 - 50%
What EF is suggestive of CHF?
Less than 40%
Increases in which ion concentration cause actin and myosin contraction in myocytes?
Calcium
What is the resting membrane potential and what ions cause this in myocytes?
RMP is around -80mV
This is caused by high intracellular k+ concentrations at rest
What causes the sharp initial upstroke (depolarisation) in the cardiac cycle?
Rapid influx of Na into the cell
What causes the initial small decrease in the cardiac cycle?
K+ channels open slowly, so K+ starts to leave the cell
(Cl- also leaves cell)
What causes the plateau in voltage in the cardiac action potential?
Ca2+ channels open and Ca influx balances the K+ outflow
What causes the sharper decrease in voltage in the cardiac action potential?
All K+ channels open and Ca2+ channels shut so main movement of ions is K+ outflow
What maintains the resting membrane potential of myocytes?
Sodium potassium ATPase
- 3 Na+ out, 2 K+ in
What are the 5 stages of the cardiac action potential cycle?
- Overshoot (depolarisation) - Na+ in
- Partial repolarisation - Slow K+ channels open
- Plateau - Ca2+ channels open (influx)
- Repolarisation - All K+ channels open
- Resting potential
What are the 3 bipolar limb leads?
I, II, III
What are the 3 unipolar limb leads?
aVR, aVF, aVL
Which ECG leads are likely to have negative traces?
aVR, V1-3
How do you identify LBBB on ECG?
W in V1 and M in V6
How do you identify RBBB on ECG?
M in V1 and W in V6
Why is RMP closest to K+ potential?
The membrane is most permeable to K+
What are the 3 pressure traces on the cardiac cycle graph?
Aortic pressure (Top)
LV pressure (steep middle)
Atrial pressure
What is the 3 letter code for pacemakers?
- Chambers paced = A, V, D, O
- Chambers sensed = A, V, D, O
- Response to sensing = T, I, D
What is the purpose of the telemetry coil of a pacemaker?
It allows programming of the pacemaker
Is the right or left ventricle wall more smooth?
Left is smoother - can result in different lead fixation methods
What is threshold?
Minimum energy needed to result in a cardiac contraction
What is capture?
The deoplarisation of the myocardium causing QRS caused by pacemaker
How does a pacemaker lead reach the left ventricle?
Through the coronary sinus
