Heart blocks: Pathology review
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Heart blocks: Pathology review
Cardiology
Cardiology
Acute coronary syndrome: Clinical sciences
Advanced cardiac life support (ACLS): Clinical (To be retired)
Supraventricular arrhythmias: Pathology review
Ventricular arrhythmias: Pathology review
Heart blocks: Pathology review
Coronary artery disease: Clinical (To be retired)
Heart failure: Clinical (To be retired)
Syncope: Clinical (To be retired)
Pericardial disease: Clinical (To be retired)
Infective endocarditis: Clinical (To be retired)
Valvular heart disease: Clinical (To be retired)
Cardiomyopathies: Clinical (To be retired)
Hypertension: Clinical (To be retired)
Hypercholesterolemia: Clinical (To be retired)
Pharmacology
Cholinomimetics: Direct agonists
Cholinomimetics: Indirect agonists (anticholinesterases)
Sympathomimetics: Direct agonists
Muscarinic antagonists
Sympatholytics: Alpha-2 agonists
Adrenergic antagonists: Presynaptic
Adrenergic antagonists: Alpha blockers
Adrenergic antagonists: Beta blockers
ACE inhibitors, ARBs and direct renin inhibitors
Thiazide and thiazide-like diuretics
Calcium channel blockers
Adrenergic antagonists: Beta blockers
cGMP mediated smooth muscle vasodilators
Calcium channel blockers
Adrenergic antagonists: Beta blockers
Class I antiarrhythmics: Sodium channel blockers
Class II antiarrhythmics: Beta blockers
Class III antiarrhythmics: Potassium channel blockers
Class IV antiarrhythmics: Calcium channel blockers and others
Lipid-lowering medications: Statins
Lipid-lowering medications: Fibrates
Miscellaneous lipid-lowering medications
Positive inotropic medications
Loop diuretics
Antiplatelet medications
Assessments
Heart blocks: Pathology review
USMLE® Step 1 questions
0 / 3 complete
Questions
USMLE® Step 1 style questions USMLE
of complete
Reproduced from: Wikimedia Commons
Which of the following is the most likely cause of this patient’s symptoms?
Memory Anchors and Partner Content
Transcript
Contributors
Sam Gillespie, BSc
Evan Debevec-McKenney
Pauline Rowsome, BSc (Hons)
Mikey is a 22 year old male college student from Vermont who was sent to the emergency department after passing out.
His vital signs show a heart rate of 40 beats per minute and a blood pressure of 90/50. On examination, there is an erythematous circular rash with central clearing.
His friends mention they recently went on a hiking trip. His ECG is as follows.
Natasha is a 60 year old female with chronic hypertension, diabetes, and peripheral vascular disease who comes to the emergency room complaining of sudden-onset, squeezing retrosternal chest pain accompanied by shortness of breath and sweating.
Her ECG is as follows. On laboratory evaluation, her troponin levels are significantly elevated.
Alright, so the normal electrical activity of the heart starts in the sinoatrial or SA node located near the opening of the superior vena cava into the right atrium.
Electrical activity is then conducted through the atrium to the atrioventricular, or AV node, after which it goes through the Bundle of His, then the right and left branches of the Bundle, and finally through the Purkinje fibers which deliver the current to the right and left ventricles.
Now, normally there is delay in conduction at the AV node and the Bundle of His, which gives some time for ventricular filling before the ventricle contracts.
A “heart block”, or AV block, occurs when conduction is delayed for too long at the AV node or the bundle of His. Also, electrical activity may be blocked at the level of the bundle branches, which are called bundle branch blocks.
Sources
- "Pathophysiology of Heart Disease" Wolters Kluwer Health (2015)
- "Chou's Electrocardiography in Clinical Practice" Saunders (2008)
- "Clinical electrophysiology of atrioventricular block" Cardiol Clin (1983)
- "Left Bundle Branch Block: Current and Future Perspectives" Circ Arrhythm Electrophysiol (2020)
- "2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society" J Am Coll Cardiol (2019)
- "Bradycardias and atrioventricular conduction block" BMJ. 2002 (2002)
- "Observations on second degree atrioventricular block, including new criteria for the differential diagnosis between type I and type II block" The American Journal of Cardiology (1972)
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