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Back To Basics: Cardiology Review I. Michael Froeschl, MD FRCPC Assistant Professor of Medicine. Overview. CAD Atherosclerosis Stable Obstructive CAD Unstable CAD: Acute Coronary Syndrome ECG/Arrhythmia Review Bradydysrhythmias Tachydysrhythmias Syncope. NB: Key Feature Questions.
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Back To Basics:Cardiology Review I Michael Froeschl, MD FRCPC Assistant Professor of Medicine
Overview • CAD • Atherosclerosis • Stable Obstructive CAD • Unstable CAD: Acute Coronary Syndrome • ECG/Arrhythmia • Review • Bradydysrhythmias • Tachydysrhythmias • Syncope
NB: Key Feature Questions Learn how to answer them!
1. Two Concepts • Ischemia: Tissue oxygen demand exceeds tissue oxygen supply • Infarction: Tissue necrosis secondary to tissue ischemia
↓ Supply Coronary obstruction Microvascular obstruction ↓ Perfusion pressure ↓ PaO2 ↓ Hemoglobin ↑ Demand ↑ Heart Rate ↑ Contractility ↑ Wall Tension 1. Supply-Demand Mismatch
1. CAD Obstructive CAD ACS Atherosclerosis
Mode-of-Life Issues Smoking Diet Exercise Alcohol Stress Medical Issues Dyslipidemia Hypertension Diabetes Mellitus Obesity 1a. Atherosclerosis Targets INTERHEART, Lancet 2004
1a. Atherosclerosis Targets “Vascular Protection” • ASA • Statins • ACE-Inhibitors or ARBs • +/- Beta-Blockers
1b. Stable Obstructive CAD Usual manifestation is Angina Pectoris: (“strangling”) chest pain secondary to myocardial ischemia
1b. Stable Obstructive CAD: DX • Clinical assessment in all • Chest Pain • Sqeezing retrosternal • Brought on by stress • Relieved by rest or NTG • Patient (age, gender, vascular risk) • Physical exam and basic blood work 3/3: Typical anginal CP 2/3: Atypical anginal CP 0-1/3: Non-anginal CP
1b. Stable Obstructive CAD: DX • Testing in some (for diagnosis and prognosis) • Functional Assessment (“stress test”) • Exercise ECG • Dipyridamole Perfusion Scan • Dobutamine Echocardiogram • Anatomical Assessment • Coronary Angiography (conventional, CT)
1b. CCS Angina Severity Scale I Ordinary activity does not cause angina; angina only with increased activity II Slight limitation of ordinary activity (> 2 blocks level, > 1 flight of stairs) III Marked limitation of ordinary activity (< 2 blocks level, < 1 flight of stairs) IV Inability to carry out any activity without discomfort; symptoms may be present at rest
1b. Stable Obstructive CAD: MX • Vascular Protection (ASA, statin, ACE-I/ARB) • Beta-Blocker (non-DHP CCB if not tolerated) • NTG • Address Risk Factors • Possibly Revascularize (PCI or CABG)
1c. Acute Chest Pain • Management: • ABC • Vitals • IV, O2, Monitor
1c. Acute Chest Pain: DDX • Myocardial Ischemia • PE • Aortic Dissection • Pneumothorax • GI Rupture • Other (pericarditis, pneumonia, GERD/PUD/gastritis, MSK, skin)
↓ Supply Coronary obstruction Microvascular obstruction ↓ Perfusion pressure ↓ PaO2 ↓ Hemoglobin ↑ Demand ↑ Heart Rate ↑ Contractility ↑ Wall Tension 1c. Acute Myocardial Ischemia
1c. Acute Coronary Syndrome • Definition: myocardial ischemia due to acute coronary insufficiency • 90% due to plaque rupture, thrombus +/- spasm
Complete Coronary Occlusion No blood flow beyond Transmural ischemia ST-elevation on ECG Localizes Reciprocates Threatened Coronary Occlusion Decreased blood flow Subendocardial ischemia ST-depression or normal Not localizing No reciprocal ST ↑ 1c. Two Manifestations of ACS
1c. STEMI • ABC; Vitals; IV, O2, Monitor • HX, O/E, ECG: STEMI • Acute reperfusion therapy (ART): lytics vs PPCI • ASA, NTG, clopidogrel, anti-coagulation (UFH), morphine; BB if compelled
1c. STEMI • Contraindications to Lytics: • 90-min assessment • CP • ECG • +/- Reperfusion Arrhythmia • Hemorrhagic stroke ever • Ischemic stroke < 3 mos • Intracranial AVM • Intracranial malignancy • Head trauma < 3 mos • Active bleeding • Aortic dissection
1c. NSTE ACS • ABC; Vitals; IV, O2, Monitor • HX, O/E, ECG: NSTE ACS • ASA • Risk Stratify (HX, PE, ECG, TNT) • Treat accordingly
1c. Complications Post-MI • Recurrent ischemia • HF/shock • Arrhythmia • Mechanical • Thromboembolic • Pericarditis • Depression
1c. Prognosis Post-MI • LV systolic function remains the most important determinant of prognosis post-MI • Usually assessed by means of echocardiogram prior to discharge
1c. Secondary Prevention: RX • ASA in all • Statin in almost all (LDL < 2) • ACE-I in most • Beta-Blocker • NTG if angina • Clopidogrel x 1 year post-ACS, post-stent • Treat risk factors
1c. Secondary Prevention: Life • Smoking • Diet • Exercise • Weight • Alcohol • Stress
2. ECG = EKG • Identify the study • Setting • Technical Details • Read: rate, rhythm, axis, alphabet • Interpret • Previous
2a. Electrical Anatomy The heart is a pump coordinated and powered by an integral electrical system
2a. Electrical Anatomy The SA Node has the steepest slope of spontaneous Phase 4 depolarization and therefore is the dominant pacer
2a. Electrical Anatomy Atrial depolarization normally flows from top to bottom and from right to left
2a. Electrical Anatomy The AV Node delays then relays electrical activation to the ventricles
2a. Electrical Anatomy The His-Purkinje System conducts electrical activation to all areas of both ventricles
2a. Electrical Anatomy • Three phases of ventricular depolarization: • Septum LR • (atrialrepolarization occurs simultaneously)
2a. Electrical Anatomy 2. Depolarization of both ventricles simultaneously from endocardium to epicardium
2a. Electrical Anatomy Ventricular repolarization ensues, from epicardium to endocardium
2a. PQRSTU QRS Segments Intervals PR ST TP PR QT
2a. PQRSTU PR ST TP Segments Intervals PR ST PR QT QRS
2a. Reading an ECG • Rate • Rhythm • Axis • Alphabet
1. Rate: “Count-Off” Method Start 150 75 Normal Rate = 60-100 bpm 100 60 300
2. Rhythm • Normally, the sinus node controls the entire heart • This is known as “Normal Sinus Rhythm” (NSR): • P wave axis is normal (0-90°) • Each P is followed by a QRS • Each QRS is preceded by a P
3. QRS Axis • If QRS + in I AND II, QRS axis is normal • If QRS not + in I AND II, there is axis deviation • Use leads I and aVF to identify the 90°-quadrant and the type of axis deviation
4. Alphabet • P waves • PR (segments and intervals) • QRS (Qs, height, width) • ST segments • T waves • QT interval
Arrhythmia = Dysrhythmia • Slow • Fast • Normal rate
2b. Bradydysrhythmias • Sinus Node • Sinus brady, pause, arrest, block • AV Junction • 2° AVB (Type I and Type II) • 3° AVB
2b. AV Block Nodal 1° AVB 2° AVB I 3° AVB Infra-Nodal 2° AVB II 3° AVB