CVS Flashcards
What is an ECG?
Electrical tracing of the heart, electrodes placed in standard positions on chest and limbs; detects electrical current generated by depolarisation and repolarisation of the atria and ventricles; voltage amplified and recorded on ECG paper as waves -> 12 lead has 10 electrodes: 4 on peripheries and 6 on chest
What is the ECG used for?
Pts with cardioresp symptoms: tachy, chest pain, dizziness, palpitations, SOB; assess pts with known cardiac disease, metabolic disorders/electrolyte imbalances; assess effects and side effects of medications
Describe the ECG waveform and what each part describes
Paper speed: 25mm/s; large sq = 5mm/0.5mV
What does a normal ECG have?
Normal rate and regular complexes with regular morphology
How to read an ECG?
- Check details/old ECGs: Indication, date and time, calibration, comparisons?;
- Rate;
- Rhythm;
- Cardiac axis: I and II + is normal, I + and II - is left axis deviation, I - and II + is right axis deviation;
- P-wave: absent, morphology (smooth) and <3 small sq, dissociated from QRS;
- PR interval: start of P to QRS, 3-5 small sq (0.12-0.2s), long=heart block, short= accessory conduction pathway;
- QRS complex: start of Q to end of S <3 small sq, wide QRS = slow ventricular depolarisation and defect in conduction, pathological Q waves > 1mm wide and >2mm deep = transmural infarct;
- QT interval: start of QRS to end of T, <440ms in men, <460ms in women, varies with HR so corrected (bazett formula), long QT = risky can lead to torsades de pointes;
- ST segment:J point (QRS ends, ST starts) should be isoelectric, if above = elevated/acute infection, if below=depressed/ischaemia;
- T wave: normally inverted in aVR and sometimes aVF, aVL, III, V1, V2, V3, T-wave abnormal if inverted in I, II, V4, V6 usually ischaemia, can be peaked or flattened in electrolyte abnormalities
What is the CXR used for?
Pts presenting with cardioresp Sx, check position of line/tubes; preop assessment; resolution pneumothoraces/pneumonia
How to read a CXR?
- Check details: pt name, DOB, date and time, indications, old CXR for comparisons;
- projection: PA (most common, pt stands facing cassette, 6ft so divergence minimised and scapula retracted), AP (sick/elderly, supine with cassette under back, 4ft, can magnify structures, scapulae not retracted) and Lateral (L/R, one side with arms raised, reduces magnification of heart, usually used in pathology for individual lobe, highlights fissures/pathology in costophrenic recesses);
- quality: coverage, orientation, rotated? (spinous processes seen), inspiration? (>8 posterior ribs seen), penetrated? (thoracic vertebral bodies through heart);
- Airway: deviation of trachea - away = tension pneumo, pleural effusion, large thoracic mass, towards = atelactasis, lung agenesis, lung collapse and pneumonectomy;
- Breathing: upper, middle and lower zones of both lung fields, normal = symmetrical, black and full of air with clear pulm vascular markings (pneumoT= one side blacker with loss of vascular markings/shadowing = interstitial disease or air space disease);
- Circulation = heart 2/3 of heart on left, 1/3 on right, no more than 1/2 of thoracic cavity;
- Diaphragm: hemidiaphragm and costophrenic/cardiophrenic angles, angles blunted = effusion, D elevated = lobar collapse/subphrenic abcess/phrenic nerve palsy, D flattened = hyperinflation (COPD/asthma);
- Everything else: soft tissue, bones (BMD, Fx);
- Final review areas
How do you classify an arrhythmia on an ECG?
Tachycardia (>100 bpm) or bradycardia (<60bpm) looking at R-R interval; QRS complex, narrow (<=120ms) or broad (>120ms); regular vs irregular rhythm. Narrow arise from top of heart (atria/AVN), broad from ventricles
How do you treat tachycardia?
Is patient stable -> NO, then defib (after synching with fast HR); if yes then give drug to help -> if slurred ECG (short P-QRS interval) with supraventricular tachycardia, it’s called Wolff-Parkinson-White syndrome and is due to accessory pathway forming
When do you use adenosine?
Supraventricular tachycardia; AVN blocker, stopping heart for 3-6s; given for long term conditions; use catheter ablation to stop the accessory pathway by burning it away
What is atrial fibrillation?
Irregular narrow complex tachycardia; heart beat arises from atria not SAN; HR travels down AVN (but if not then ventricular fibrillation can occur) -> if recent onset (<48h) then electrical cardioversion is used, if not then drugs given (amiodarone, flecanide all IV); need to decide to give clot busters to prevent clots in left atrium
What is atrial flutter?
Circuit forms in atrium; slightly more organised than atrial fibrillation; regular, with every 3/4 cycles passing through to the ventricles
How do you treat atrial fibrillation?
Rate control and anticoagulation: beta blockers, rate limiting CCB, digoxin;
NB: with rhythm control >48h onset, no anticoag, only in haemodynamic compromise;
can use electrical cardioversion.
Most common in elderly and biggest killer is stroke from clot in LA
What is atrioventricular dissociation?
Atria and ventricles aren’t associated with each other; complete heart block; p wave and QRS aren’t associated; need to give pacemaker as heart could stop
What is trifascicular block?
Broad QRS complexes (slow conduction throughout ventricles, P-QRS distance is very long (1st degree AV block) Slow conduction in left anterior hemifascicular block, right bundle branch block and SAN to AVN; give pacemaker
What are the 4 valves of the heart?
Left: Mitral (AV), aortic; right: Tricuspid (AV), pulmonary
What is the function of the aortic valve?
Outlet of LV; located between LV and aorta; usually 3 cusps that open with heart beat (2% have 2 cusps); leaflets open and close and let blood through (during systole the pressure in LV rises, when pressure in ventricle>>aorta; aortic valve opens; when pressure in LV drops lower than aorta, aortic valve closes and gives rise to aortic component of 2nd heart sound
What is diastole and systole?
Diastole: ventricular relaxation and filling; systole: ventricular contraction and ejection; diastole > LUB > systole > DUB > diastole
What is aortic stenosis?
Common, affecting 5% >60y; S+S: *SOB, chest pain*, *syncope, tired, palpitation. *: RED FLAG Sx, one of these symptoms can lead to death within the next 2 y; mild stenosis valve area is between 1.5 and 2.5cm2
How can you diagnose/manage/treat aortic stenosis?
Hx: red flag Sx, exercise intolerance, palpitations, sx of HF; Examination: slow rising pulse, narrow PP, ejection systolic murmur, soft/absent 2nd heart sound, displaced or heaving apex beat; signs of HR/PE. ECG: tall QRS waves = ventricular increase; blood tests: anything to explain symptoms, BNP most useful
How can you image the heart for aortic stenosis?
ECG: transthoracic/transoesophageal; velocity through valve (Bernoulli principle:fast moving fluid generates low pressure, slow moving generates high pressure - pressure calculation). calculation of aortic valve areas, which knowing area and pressure helps establish significant narrowing of valve
What is aortic regurgitation?
Valves don’t close completely, leaking blood into heart; History: SOB, palpitations, sx of HF; examination: high volume pulse, collapsing pulse, wide pulse, diastolic murmur, signs of HF
How can you diagnose/manage/treat aortic regurgitation?
History: SOB, palpitations, sx of HF; examination: high volume pulse, collapsing pulse, wide pulse, diastolic murmur, signs of HF; take blood tests; X ray (heart and fluid); ECG; CT/MRI/angiogram
What is the cause of aortic stenosis and aortic regurgitation?
Stenosis: calcification, bicuspid, infective endocarditis; regurg: rheumatic heart disease, bicuspid valve, dilation of aorta, infective endocarditis
How do you treat aortic stenosis and aortic regurgitation?
Conservative supportive measures; medical: managing HF sx, arrhythmia, anticoag; surgical: optimal timing for surgery, percutaneous intervention, open heart surgery, using the euroscore (helps distinguish pts who will benefit from open heart, TAVI or no intervention: <20 for surgical consideration; >20 consider TAVI) and in high risk cases, consider likelihood of success, or can just leave it at medical therapy: balloon valvuloplasty
What is percutaneous intervention?
Transcatheter aortic valve implantation -> femoral artery to heart, crossing narrowing with balloon and then inflate to open valve, place the TAV, then open the balloon up again to open the TAV, then the valve is placed.
How is open heart surgery used for valve replacement?
Open chest, remove heart, open aorta and remove diseased aortic valve and then m=place the new valve (porcine - 7y no anticoag or st. jude valve - 25y with anticoag) and close up
What are acute coronary syndromes?
Spectrum of diseases
How would you assess STEMI in A+E?
Hx: rapid, thorough, time of onset of chest discomfort, PMHx, RF, contraindications for dual antiplatlets; physical exam; investigations (ECG!!!)
How can you localise the place of infarction in the heart on ECG?
To Dx a posterior infarct you can change the place of leads V4-6 and place them underneath the inferior angle of the scapula (V7,8,9) in a straight line, which gives ST elevation if post infarct
How do you use calcium scoring?
x
What is the ischaemic cascade?
x
What is typical angina?
3/3:
- constricting discomfort in front of chest or neck/shoulders/jaw/arms,
- precipitated by physical exertion,
- relieved by rest or GTN in 5 min;
atypical = 2/3,
non-anginal chest pain=1/3
What are the 4 causes of HF?
- IHD as main reason (CAD mainly), heart needs to work harder, causing LV hypertrophy, so need more energy, which isn’t being supplied, leading to HF;
- HTN = IHD and HF are more likely with HTN, heart needs to work harder to push out blood;
- Valvular HD: increases likelihood of HF;
- dilated cardiomyopathy too;
- hormonal: increased sympathetic activation, so more pressure on heart = more likely to fail, increased RAAS which increases blood vol, work done by heart and can vasoconstrict and cardiac remodelling
What are the signs and symptoms of HF?
- Symptoms:
- Breathlessness, tachycardia, oedema;
- signs:
- third heart sound (low-pitched sound during early diastole due to rapid deceleration of blood flow from atria to ventricles),
- raised JVP indicative of increased volume and good prognostic indicator of poor outcome
What investigations would you carry out for HF Dx?
Biomarkers are the most important values -> sensitive indicator for HF (NT-pro is more specific), stretch on heart causes release of BNP; Echo used to look at heart
How do you treat HF?
Generally start with ACEi, with loop diuretic for volume overload. ALL medications helps increase life but not treat the disease; resynch therapy is for pts with arrhythmia
