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Cardiovascular System Notes

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Cardiovascular System Contents Acute Coronary Syndrome..................................................................................... 1 STEMI.................................................................................................................. 1 NSTEMI............................................................................................................... 5 Angina Pectoris (IHD).......................................................................................... 6 Heart Failure.......................................................................................................... 9 Heart Valve Disease............................................................................................. 13 Mitral Stenosis.................................................................................................. 13 Mitral Regurgitation.......................................................................................... 14 Aortic Stenosis.................................................................................................. 15 Aortic Regurgitation.......................................................................................... 15 Heart Catheterisation....................................................................................... 16 Acute Pulmonary Oedema................................................................................... 16 Arrhythmias......................................................................................................... 17 Supraventricular Arrhythmias...........................................................................17 Ventricular Arrhythmias.................................................................................... 18 Ventricular Tachycardia.................................................................................18 Torsade de Pointes......................................................................................... 19 Ventricular Fibrillation....................................................................................19 Bradycardias................................................................................................. 19 Antiarrhythmic Drugs....................................................................................... 20 Infective Endocarditis.......................................................................................... 21 Chest Pain Summary............................................................................................ 23

Acute Coronary Syndrome STEMI
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Most common cause of mortality in Western World. Affects ~0.5% of the population/year

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Majority due to occlusive coronary artery thrombus overlying an ulcerated or fissured stenotic plaque Pathogenesis involves a dynamic interaction between severe coronary atherosclerosis, acute plaque rupture, superimposed thrombosis with platelet activation and vasospasm

Microscopic changes following acute MI Time after onset of symptoms
Diagnosis

1. Cardiac Enzymes (intracellular enzymes leak out of infarcted myocardium)
 CK - peaks at 24h. Also produced by skeletal muscle + brain therefore request myocardium-bound fraction (CK-MB) which is specific for myocardial damage. Serum level of the enzyme relates to site of infarct
 Troponin - most reliable 12h post event. Highly specific (proteins involved in muscle contraction). Remain elevated for weeks therefore use CK to assess infarction in pt whose trop remains high from previous MI

2. ECG
 Hyperacute changes = tall, pointed T-waves followed by ST elevation. This is followed by T wave inversion. R wave voltage then decreases and Q waves develop
 Weeks - months = T wave may become upright again, Q waves remain

Site of infarction can be deduced from affected leads:

Inferior MI - involves leads II, III and aVF Anterior MI - affects precordial leads Anteroseptal MI - affects leads V1-V3 Lateral MI - affects leads I and aVL and V5-V6 Posterior MI - tall R wave in V1 and V2 with ST depression and upright T waves Note that there may be reciprocal ST-depression in leads opposite the site of infarction Development of new LBBB is an indicator of acute MI. However, it is a common abnormality - look at old ECGs Management
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Emergency Care o Aspirin 300mg PO o Pain-relief 5-10mg morphine + metoclopramide (anti-emetic)

o o o

Sublingual GTN (unless hypotensive) Oxygen via non-rebreathe (if sats 180) Recent retinal laser treatment Major bleeding seen in up to 3% of pts 2 main thrombolytics are streptokinase + alteplase (recombinant tissue plasminogen activator tPA). Streptokinase induces an antibody response which ↓effectiveness of repeat dose + ↑risk of anaphylactic reaction. Should not be readministered 5days - 2 years following initial treatment Cheapest, often 1st-line in inf MI. Can  hypotension or allergic reaction. Usually only given once Less hypotension. Better than streptokinase for ant MI. requires heparin infusion for 48h post administration Given as bolus injection so can ↓ 'door-to-needle' time

Primary Coronary Angioplasty (PCA) o Primary PCI with stent placement is now the preferred method of revascularisation and is indicated if the pt presents within 90mins of onset of pain o Involves immediate transfer to cath lab with intention of opening artery with stent placement (drug-eluting stents are preferred) o Many hospitals now have 24h PCI facilities o Early revascularisation prevents scar formation, ↓occurrence of heart failure in the future and ↓incidence of ventricular arrhythmias caused by scar formation

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Other therapy in the acute phase o Aspirin: 300mg prescribed early  30% ↓in deaths. Use clopidogrel if aspirin sensitivity o Β-blockers: iv in acute phase to limit infarct size, ↓risk of arrhythmias and ↓pain. Particularly appropriate when pt has tachycardia (in absence of HF), relative HTN or pain unresponsive to opioids o ACEIs: most valuable in pts with Sx of HF or impaired LV function o Statins: started immediately as per management of NSTEMI o Heparin: forms part of most thrombolytic regimes over 1st 24h. should then be given until pt mobile o Control of BM: Even if pt not a known diabetic as blood glucose often
↑with a variety of physical stressors

Complication Sudden death Arrhythmias Sinus bradycardia Persistent pain Angina Cardiac failure

Interval Within hours First few days First few days

Mechanism Ventricular fibrillation Ventricular ectopics, VT, VF, AF AV block (common in inf MI)

12 hrs to few days Immediate or delayed (weeks) Variable

Progressive myocardial necrosis

Mitral incompetence Pericarditis

First few days

Cardiac rupture with VSDs Mural thrombosis Ventricular aneurysm Dressler's syndrome PE Late Ventricular arrhythmias

3-5days

2-4days

Ischaemia of non-infarcted mm Ventricular dysfunction following mm necrosis, arrhythmias Papillary mm dysfunction, necrosis or rupture

> 1 week

Transmural infarct with inflammation of pericardium Weakening of wall following mm necrosis +
acute inflammation Abnormal endothelial surface following infarction

>4 weeks

Stretching of newly formed collaged scar tissue

Weeksmonths
>1 week
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Autoimmune DVT in lower limbs
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Remember with mnemonic - DARTH VADER Death, Arrhythmia (heart block), Ruptured myocardium, Thrombus (mural), Heart failure/shock/arrest Ventricular aneurysm/septal rupture, Another MI, Dressler's (+Pericarditis), Emboli, Regurgitant murmur/VSD Subsequent inpatient management
- Bed rest for 1st 24h. If uncomplicated, pt can sit out of bed, use commode +
undertake self-care. Ambulation started on next day + exercise gradually built up

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DVT and PE: prevented with subcut LMWH Intraventricular thrombus + systemic emboli: may be confirmed on echo +
treated with iv heparin followed by oral anticoagulation Pericarditis: causes pain that is sharp + varies with posture + resp + audible pericardial rub. May be treated with high dose aspirin, NSAIDs or steroids. Dressler's = fever, leucocytosis, pericarditis + serositis up to 3 months postMI due to autoimmune response to damaged myocardium Late ventricular arrhythmias: liable to recur + associated with high mortality. If induced by ischaemia, revascularisation should be considered. If this is unlikely, antiarrhythmic agents (e.g. β-blockers + amiodarone) may be given. Implantable defibrillator may be indicated

Secondary Prevention
- Risk stratification: post-MI pts should undergo echo to assess valve + systolic function. Most pts can safely undergo a limited exercise test after being painfree for 5-7days. If normal, followed up in clinic with no further tests. ↑risk of further events with continuing angina, HF or +ve stress test (these pts should have angiography prior to discharge)
- Smoking: those who stop smoking have mortality of 1.5% on GRACE/TIMI score) o B-blocker (calcium channel-blockers used if contraindicated) o ACEI (low risk pts gain only marginal benefit. Better in pts with HF or ant MI) o Statin (even if initial cholesterol normal)
- Aldosterone antagonists: pts who've had acute MI + have Sx/signs of HF or LV systolic dysfunction should be started on aldosterone antagonist (epleronone) therapy within 3-14days of MI

NSTEMI Symptoms: Characteristic central crushing chest pain or may present with non-specific symptoms. Pts with chronic stable angina may note their pain is no longer relieved by GTN or it is ↑ in intensity or occurs at rest. This requires urgent assessment. ~1/3 of referrals to general medicine are for chest pain Diagnosis: ECG may show ST depression + T-wave flattening or inversion. Deeper changes are more worrying. Initial ECG may be normal - therefore serial ones are needed, preferably when pain occurs, to show dynamic ischaemia TIMI Risk Score (used in unstable angina + NSTEMI) score 1 for each risk factor: Age>65 Known coronary aa ds (stenosis >50% of angiography)
>3 CAD RFs (HTN, hyperlipidaemia, DM, FH, smoking)

↑cardiac markers ST deviation on ECG
>2 episodes of rest pain in last 24h Aspirin use in last 7 days 0-2 is low risk, 3-4 intermediate, 5-7 high risk Calculates % risk at 14 days of all cause mortality, new/recurrent MI or severe recurrent ischaemia Management:
- Emergency - analgesia, O2, nitrates (unless hypotensive)
- Drugs: o Aspirin - 300mg PO. Then continue at 75mg o Clopidogrel - significantly improves outcomes when combined with aspirin. Also used if contraindication to aspirin. 1st dose 300mg then continue at 75mg o Heparin - given until pain-free for 48h. Usually BD enoxaparin o B-blockers - unless contraindicated (e.g. HF or known LV dysfunction). Antianginal effects + ↓progression to acute STEMI, ↓arrhythmias o Diltiazem - antianginal with -ve chronotropic effects o Statins - started regardless of cholesterol levels (plaque stabilising effects) o ACEIs - start low dose + wait 12h until acute event settles (as hypotension is a risk)
>90% of pts with NSTEMI with become pain-free with above treatment. If pain continues, complications (e.g. shock) ensue and/or ECG changes progress then additional therapy is needed. Pt should be transferred to centre with PCI available
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Thrombolysis: no proven benefit in NSTEMI. Reserved for STEMI or new LBBB only Angiography + angioplasty: if ongoing symptoms, progressive ECG changes Troponin: 12h after pain onset. Highly specific + has prognostic value. Pts with non-evolving ECGs who are pain free with -ve trop can be discharged with exercise tolerance test and CV risk stratification as outpatients. Pts with +ve trop are high risk + should be evaluated for revascularisation as inpatients

PREVENTION In pts with proven NSTEMI, 1yr mortality=20%. All pts should have CV risk assessed
+ modifications made. Long-term antiplatelets, statins, B-blockers + ACEIs prescribed for all (unless contraindicated) Need for angioplasty/CABG considered with stress test or angiography

Angina Pectoris (IHD) Stable angina: chest pain due to myocardial ischaemia, generally due to obstruction or spasm of coronary aas. Precipitated by activity with no Sx at rest or with GTN Unstable angina: (crescendo angina) A form of ACS. Has at least 1 of: chest pain at rest (lasts >10mins); severe or new-onset pain; occurs in crescendo pattern (distinctly more severe, prolonged or frequent than before)

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