Heart blocks: Pathology review

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Heart blocks: Pathology review

Prerequisite basic sciences

Prerequisite basic sciences

Anatomy clinical correlates: Anterior and posterior abdominal wall

Anatomy clinical correlates: Inguinal region

Anatomy clinical correlates: Other abdominal organs

Anatomy clinical correlates: Peritoneum and diaphragm

Anatomy clinical correlates: Viscera of the gastrointestinal tract

Appendicitis: Pathology review

Diverticular disease: Pathology review

Gallbladder disorders: Pathology review

GERD, peptic ulcers, gastritis, and stomach cancer: Pathology review

Inflammatory bowel disease: Pathology review

Pancreatitis: Pathology review

Anatomy clinical correlates: Anterior blood supply to the brain

Anatomy clinical correlates: Cerebellum and brainstem

Anatomy clinical correlates: Cerebral hemispheres

Anatomy clinical correlates: Posterior blood supply to the brain

Amnesia, dissociative disorders and delirium: Pathology review

Central nervous system infections: Pathology review

Cerebral vascular disease: Pathology review

Dementia: Pathology review

Drug misuse, intoxication and withdrawal: Alcohol: Pathology review

Drug misuse, intoxication and withdrawal: Hallucinogens: Pathology review

Drug misuse, intoxication and withdrawal: Other depressants: Pathology review

Drug misuse, intoxication and withdrawal: Stimulants: Pathology review

Mood disorders: Pathology review

Seizures: Pathology review

Traumatic brain injury: Pathology review

Anatomy clinical correlates: Breast

Anatomy clinical correlates: Heart

Anatomy clinical correlates: Mediastinum

Anatomy clinical correlates: Pleura and lungs

Anatomy clinical correlates: Thoracic wall

Aortic dissections and aneurysms: Pathology review

Coronary artery disease: Pathology review

Deep vein thrombosis and pulmonary embolism: Pathology review

GERD, peptic ulcers, gastritis, and stomach cancer: Pathology review

Pleural effusion, pneumothorax, hemothorax and atelectasis: Pathology review

Anatomy clinical correlates: Viscera of the gastrointestinal tract

Gastrointestinal bleeding: Pathology review

Anatomy clinical correlates: Bones, fascia and muscles of the neck

Anatomy clinical correlates: Skull, face and scalp

Anatomy clinical correlates: Temporal regions, oral cavity and nose

Anatomy clinical correlates: Trigeminal nerve (CN V)

Anatomy clinical correlates: Vessels, nerves and lymphatics of the neck

Headaches: Pathology review

Anatomy clinical correlates: Anterior blood supply to the brain

Anatomy clinical correlates: Cerebellum and brainstem

Anatomy clinical correlates: Cerebral hemispheres

Anatomy clinical correlates: Posterior blood supply to the brain

Cerebral vascular disease: Pathology review

Anatomy clinical correlates: Female pelvis and perineum

Cervical cancer: Pathology review

Complications during pregnancy: Pathology review

Ovarian cysts and tumors: Pathology review

Sexually transmitted infections: Vaginitis and cervicitis: Pathology review

Urinary tract infections: Pathology review

Uterine disorders: Pathology review

Vaginal and vulvar disorders: Pathology review

Anatomy clinical correlates: Heart

Anatomy clinical correlates: Mediastinum

Anatomy clinical correlates: Pleura and lungs

Anatomy clinical correlates: Thoracic wall

Apnea, hypoventilation and pulmonary hypertension: Pathology review

Deep vein thrombosis and pulmonary embolism: Pathology review

Heart failure: Pathology review

Lung cancer and mesothelioma: Pathology review

Obstructive lung diseases: Pathology review

Pleural effusion, pneumothorax, hemothorax and atelectasis: Pathology review

Pneumonia: Pathology review

Restrictive lung diseases: Pathology review

Tuberculosis: Pathology review

Drug misuse, intoxication and withdrawal: Alcohol: Pathology review

Drug misuse, intoxication and withdrawal: Hallucinogens: Pathology review

Drug misuse, intoxication and withdrawal: Other depressants: Pathology review

Drug misuse, intoxication and withdrawal: Stimulants: Pathology review

Environmental and chemical toxicities: Pathology review

Medication overdoses and toxicities: Pathology review

Prerequisite basic sciences

Shock: Pathology review

Assessments

Heart blocks: Pathology review

USMLE® Step 1 questions

0 / 3 complete

Questions

USMLE® Step 1 style questions USMLE

of complete

A 71-year-old man presents to the emergency department with sudden onset chest pain. He was sitting at home watching television when he noticed the pain, characterized as a sharp pressure-like sensation in the left side of his chest. He is having difficulty catching his breath. Medical history is significant for hypertension, COPD, chronic kidney disease, and coronary artery disease. He takes amlodipine, lisinopril, aspirin, salmeterol, and albuterol. His father died from a heart attack at age 50. He smokes one pack of cigarettes per day and drinks occasionally. His temperature is 37.2°C (99°F), pulse is 105/min, respirations are 23/min, blood pressure is 90/60 mmHg, and oxygen saturation is 90% on room air. He appears pale and diaphoretic. Physical exam shows a holosystolic murmur at the left mid sternal border that increases with supine leg raise. Lung examination is normal. An ECG is obtained and shows the following:  



 Reproduced from: Wikimedia Commons

Which of the following is the most likely cause of this patient’s symptoms?  

Transcript

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

  1. "Pathophysiology of Heart Disease" Wolters Kluwer Health (2015)
  2. "Chou's Electrocardiography in Clinical Practice" Saunders (2008)
  3. "Clinical electrophysiology of atrioventricular block" Cardiol Clin (1983)
  4. "Left Bundle Branch Block: Current and Future Perspectives" Circ Arrhythm Electrophysiol (2020)
  5. "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)
  6. "Bradycardias and atrioventricular conduction block" BMJ. 2002 (2002)
  7. "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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