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Abnormal Foundations of the Cardiovascular System

CPR APPLICATIONS FOUNDATION · CHAPTER 6 · ABNORMAL

Abnormal Foundations of the Cardiovascular System

Organize the chapter before drilling into individual CPR concepts.

Supplemental foundation map: this page orients the detailed CPR Applications for Chapter 6. It is not part of the canonical CPR object inventory.

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6.21 · SOURCE CPR FOUNDATION

Concept

Abnormal cardiovascular physiology is a limited set of deviations from baseline hemodynamics. Step 1 rewards linking mechanism to pattern: ischemia, pump failure, valve failure, arrhythmia, vascular disease, or shock. Once the mechanism is identified, the symptoms and complications become predictable.

Pattern

Most cardiovascular vignettes are variations on four themes: reduced coronary flow, pump failure, valve dysfunction, or failed perfusion maintenance. The clinical presentation usually reflects low forward flow, upstream congestion, pressure overload, volume overload, thrombosis, or inadequate vascular tone. Naming the diagnosis too early can obscure the hemodynamic category being tested.

Rule

  1. Start with the hemodynamic label: decide whether the problem is ischemia, contractile failure, filling failure, stenosis, regurgitation, preload collapse, SVR collapse, or obstruction.
  2. Predict forward flow and backup: low output causes hypoperfusion, while pressure or volume overload causes congestion and remodeling.
  3. Use mechanism to predict complications: ischemia causes infarction and arrhythmias, valve disease causes remodeling and murmurs, and shock causes end-organ hypoperfusion.

Applications

  • Exertional chest pain → supply-demand mismatch
  • Dyspnea orthopnea edema → heart failure syndrome
  • Fever with a new regurgitant murmur, bacteremia, or embolic findings → evaluate for infective endocarditis; the murmur alone does not confirm a diagnosis
  • Hypotension cool extremities → shock physiology
  • Named diagnosis too early → missed mechanism category
  • Tip: Naming the disease too early often misses the mechanism category that the question is really testing.

CPR APPLICATIONS · ACTIVE REASONING

Identify the hemodynamic failure before the diagnosis

Make a prediction before checking the explanation. Every worked answer is also available below without scripts. No learner answers are transmitted or retained.

Decision 1. A patient is hypotensive with cool extremities, distended neck veins and pulmonary crackles after a large myocardial infarction. Which disturbance best explains the pattern?
Reveal worked answer and changed-variable prompt

Best answer: Low cardiac output with elevated cardiac filling pressures. Correct. Pump failure can cause systemic hypoperfusion alongside upstream pulmonary and systemic venous congestion.

Transfer: How would low JVP and clear lungs change the shock differential?

Decision 2. A patient develops acute severe mitral regurgitation. Where is the immediate extra volume and pressure directed during systole?
Reveal worked answer and changed-variable prompt

Best answer: From left ventricle back into left atrium and pulmonary veins. Correct. Regurgitant systolic flow raises left atrial pressure and may abruptly cause pulmonary edema.

Transfer: Why may acute severe regurgitation cause pulmonary edema without long-standing chamber enlargement?

Decision 3. A patient with aortic stenosis develops exertional syncope. What mechanism best fits?
Reveal worked answer and changed-variable prompt

Best answer: Limited augmentation of forward flow against an obstructed outflow tract. Correct. Severe fixed outflow obstruction can limit cardiac output reserve during increased activity.

Transfer: What would changing the clinical finding to orthopnea make you examine? Elevated filling pressures and congestion.

Change the mechanism

Reference consequences without scripts
  • Findings: hypotension, cool skin, high JVP, pulmonary edema: Cardiogenic shock from pump dysfunction is high on the differential.
  • Findings: hypotension, low JVP, clear lungs after hemorrhage: Loss of preload from hypovolemia is more likely.
  • Findings: hypotension, warm skin, low SVR in early septic shock: Distributive vasodilation is prominent; flow may be elevated or low depending on stage and context.

Explain it back: State the causal chain in your own words and identify which observation would falsify your first prediction.

These are educational, unscored self-checks rather than validated assessments or clinical treatment advice.

How to use this foundation map

  1. Identify the organizing mechanism.
  2. Recognize the pattern.
  3. Restate the rule without looking.
  4. Test transfer with the applications and question practice.

Pair CPR with the 5P Approach™ when solving cases and questions.

Back to Chapter 6 in the Foundations Library · USMLE Step 1 resources