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Practical Electrocardiography - Rate and Rhythm. Scott Ewing, D.O. Cardiology Fellow August 16, 2006. Syllabus. Introduction Axis Determination Atrial Arrhythmias, Bradycardias, and AV Conduction Block Junctional and Broad Complex Tachycardias
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Practical Electrocardiography- Rate and Rhythm Scott Ewing, D.O. Cardiology Fellow August 16, 2006
Syllabus • Introduction • Axis Determination • Atrial Arrhythmias, Bradycardias, and AV Conduction Block • Junctional and Broad Complex Tachycardias • Myocardial Ischemia and Acute Myocardial Infarction • Conditions Affecting the Left Side of the Heart • Conditions Affecting the Right Side of the Heart • Conditions Not Primarily Affecting the Heart • Exercise Tolerance Testing
Sinus Bradycardia • Pathophysiology • Increased vagal tone in athletes • Inferior wall myocardial infarction • Digitalis glycosides, beta-blockers, calcium channel-blocking agents, class I antiarrhythmic agents, amiodarone • Other drugs, toxins, environmental exposure (lithium, paclitaxel, toluene, dimethyl sulfoxide, topical ophthalmic acetylcholine, fentanyl, alfentanil, sufentanil, reserpine, clonidine) • Electrolyte disorders • Infection (diphtheria, rheumatic fever,viral myocarditis) • Sleep apnea • Hypoglycemia • Hypothyroidism • Hypothermia • Increased intracranial pressure.
Sinus Tachycardia • Pathophysiology • Hypoxia • Hypovolemia / Sepsis • Pain • Fever • Anxiety • Hyperthyroidism • PE • Exercise • Drugs (nicotine, caffeine, atropine, salbutamol, cocaine, amphetamines, methamphetamines, ecstasy)
1st Degree AV Block • Pathophysiology • PR interval represents time needed for electrical impulse from sinoatrial node to conduct through the atria, AV node, bundle of His, bundle branches, and Purkinje fibers • PR interval prolongation due to conduction delay within the right atrium, the AV node, or the His-Purkinje system • AV nodal dysfunction accounts for the majority of cases • First-degree AV block caused by conduction delay in the His-Purkinje system often is associated with bundle-branch block
Karel Frederik Wenckebach • Attended the University of Utrecht, Netherlands and received his doctorate in 1888 • Spent his assistant period at the institutes of zoology, and for pathological and normal anatomy in Utrecht • 1901 was appointed professor of internal medicine at Groningen, Netherlands • Held the same tenure at Strasbourg , France 1911-1914 • Followed a call to Vienna, Austria, where he retired from his chair in 1929 • Early work concerned embryology, later concentrated his efforts in the study of the pathology and clinics of heart and circulatory diseases • Apart from his well known phenomenon, he wrote one of the first descriptions of the beneficial effects of the quinine alkaloids on arrhythmias and that its successful use was mainly in patients with auricular fibrillation or recent onset (1903-1904) • Wrote an important monograph on beriberi in 1934
2nd Degree Mobitz Type I AV Block • Pathophysiology • Conduction disturbance in the AV node • Rarely secondary to AV nodal structural abnormalities when the QRS complex is narrow in width and no underlying cardiac disease is present • May be vagally mediated (well-trained athletes, digoxin excess, neurally mediated syncopal syndromes) • Vagally mediated AV block improves with exercise and may occur more commonly during sleep when parasympathetic tone dominates • Cardioactive drugs (digoxin, beta-blockers, calcium channel blockers, and certain antiarrhythmic drugs) • Various inflammatory, infiltrative, metabolic, endocrine, and collagen vascular disorders
2nd Degree Mobitz Type II AV Block • Intermittent failure of conduction of P waves • PR interval is constant (may be normal or prolonged) • May include wide QRS • May progress to complete third degree AV block
Woldemar Mobitz • Studied in Freiburg im Breisgau and in Munich, where he obtained his doctorate in 1914 • Hospital service and assistant years in the surgical clinics in Berlin and Halle, as well as the medical clinics in Munich and Freiburg • 1924 he was habilitated for internal medicine in Munich, and in 1928 he became professor extraordinary at Freiburg im Breisgau • Became head physician at the university medical clinic, then director of the medical clinic of the city hospital in Magdeburg • Remained in Magdeburg until it was occupied by the Russian army in 1945 • His main work concerns heart and circulation
3rd Degree Heart Block • Pathophysiology • Class Ia antiarrhythmics (eg, quinidine, procainamide, disopyramide) • Class Ic antiarrhythmics (eg, flecainide, encainide, propafenone) • Class II antiarrhythmics (beta-blockers) • Class III antiarrhythmics (eg, amiodarone, sotalol, dofetilide, ibutilide) • Class IV antiarrhythmics (calcium channel blockers) • Digoxin or other cardiac glycosides • Infection • Profound hypervagotonicity • Anterior wall MI • Cardiomyopathy, eg, Lyme carditis and acute rheumatic fever • Metabolic disturbances, eg, severe hyperkalemia
Atrial Fibrillation • Pathophysiology • Long-standing hypertension • Valvular heart disease (rheumatic) • Left ventricular hypertrophy • Coronary artery disease • Diabetes mellitus • AMI • CHF • Pulmonary embolism • Cardiomyopathy • Pericarditis • Hyperthyroidism • Ethanol use (holiday heart) • Cardiothoracic surgery (postoperative) • Use of illegal drugs, such as cocaine or amphetamine derivatives • Over-the-counter herbs (eg, ephedra, ginseng) • Idiopathic or “Lone” AF
Atrial Flutter • Pathophysiology • Long-standing hypertension • Valvular heart disease (rheumatic) • Left ventricular hypertrophy • Coronary artery disease with or without depressed left ventricular function • CHF • Pericarditis • Pulmonary embolism • Hyperthyroidism • Diabetes Mellitus • Postoperative revascularization • Digitalis toxicity
