IHD & Arrhythmias Revision Lecture Slides PDF

IHD & Arrythmias: RevisioIschaemic heart disease and arrhythmiasLect ure + Q&A Dr. Lucy Dale Dr. Alex Lee Causes of myocardial ischemia • Atherosclerosis – plaque rupture, plaque erosion - Obesity, diabetes, hypertension, hypercholesterolemia • Blood clot - Atherosclerosis causing a thrombus, embo...

IHD & Arrythmias: RevisioIschaemic heart disease and arrhythmiasLect ure + Q&A Dr. Lucy Dale Dr. Alex Lee Causes of myocardial ischemia • Atherosclerosis – plaque rupture, plaque erosion - Obesity, diabetes, hypertension, hypercholesterolemia • Blood clot - Atherosclerosis causing a thrombus, emboli • Coronary artery spasm - Takotsubo cardiomyopathy, alcohol withdrawal IHD learning outcomes • Describe the causes of ischemic heart disease • Understand the microscopic features of an atheroma • Describe the clinical and investigatory features of an acute MI • Describe the complications of an acute MI Microscopic features of coronary artery atheroma Angina Pectoris Stable angina: Chest pain on exertion Unstable angina: Chest pain at rest with no pathological ECG changes or biomarker changes (troponin) Unstable angina is classified as an acute coronary syndrome and warrants admission into hospital Acute coronary syndromes • Unstable angina • NSTEMI • STEMI Clinical features of an ACS NSTEMI vs STEMI STEMI: Major artery of heart becomes completely blocked. Diagnosed based on ECG findings only. NSTEMI: Major artery of the heart becomes severely narrowed or transiently blocked. Diagnosed based on ECG findings and cardiac biomarkers. The “ST Segment” STEMI NSTEMI Cardiac biomarkers Complications of an acute MI Arrythmias What is arrhythmia? (or rather what is ‘rhythmia’?) • Sino-atrial node fires • Atrial depolarisation • Atrio-ventricular node • Pause • Ventricular depolarisation • Pause (repolarisation) • Ready for next cycle Why does it matter? Shock Electric Signals Contraction • Output • Cardiac Profusion Ischaemia How do we categorise arrhythmias? • Rate: Fast vs Slow (tachy-arrhythmia, brady-arrhythmia, tachy-bradyarrhythmia) • Size of complexes: Narrow vs Broad • Origin: atrial, AV, ventricular, ectopic, re-entrant/short circuit • Constant vs paroxysmal • Lots of overlap and special cases – use these as a learning tool at this stage • Instead, worry about the clinical significance while in partner schools on placements Sinus tachycardia …As well as sinus bradycardia Atrial fibrillation, Atrial flutter • A type of SVT (if fast) • Narrow complex usually (what if there is concurrent/pre-existing heart block?) • Could be fast or slow • AF with fast/slow ventricular response • The typical flutter has a heart rate roughly divisible by 300 (eg 150, 100, 75, 50.. etc) • Treatment can either focus on converting to normal rhythm or controlling the ventricular rate Atrial fibrillation - No discernible P waves Irregularly irregular Atrial flutter – saw tooth WPW syndrome (Wolff Parkinson White) • A type of SVT • Congenital • Due to short circuit/accessary pathway • Cardiac ablation a potential treatment • Read up on: (AVRT/AVNRT) – advanced content. Not main focus but important to be aware Accessary pathway ‘short-cut’ No AV delay Normal conduction With AV delay Wolff Parkinson White Syndrome Delta Wave T wave opposite QRS concordance (Sometimes) And that leads us to… supraventricular tachycardia • A definition based on origin • Supra-ventricular: what is above the bundle of His • Very broad definition – many subtypes • To be more specific - ?regular ?irregular • Usually has narrow complexes Ventricular tachycardia/ventricular fibrillation VT/VF •GET HELP!! • Broad complex • Fast rate • Pulseless VT is treated as cardiac arrest Long QTc and Torsades de pointes • Certain medications mixed with long QTc • Can also be related to electrolyte imbalance • Broad complex • Polymorphic • Can be treated with magnesium IV Atrio-ventricular heart block) • 1st Degree: long PR interval • 2nd Degree • Mobitz Type 1 (Wenckebach): progressive prolongation, dropped beat then reset • Mobitz Type 2: fixed ratio (more likely to be problematic than type 1) • 3rd Degree/Complete heart block • Might need pacing as definitive treatment Bundle branch block (Left vs right) Heart Block • Tri-fascicular block • Refer to cardiology lecture Paced rhythm • Recognise pacing spikes • Appreciate paced QRS complexes look ‘x2222’ START CPR!! Pulseless electrical activity (PEA) Pulseless VT VF Asystole