Cardiac cycle in pathologic states

Valvular Stenosis - Stuck Doors, Big Problems

• Stenosis ↑ afterload or ↑ filling pressure, causing pressure overload & ventricular hypertrophy.
• Leads to concentric hypertrophy (sarcomeres added in parallel).

• Aortic Stenosis (AS): Obstruction of LV outflow.

  • Murmur: Harsh crescendo-decrescendo systolic ejection murmur, radiates to carotids.
  • Causes: Senile calcification, bicuspid aortic valve.
  • P-V Loop: ↑ LV pressures, ↑ ESV, ↓ SV. Loop shifts right & grows taller.
  • 📌 SAD Triad: Syncope, Angina, Dyspnea on exertion.

• Mitral Stenosis (MS): Obstruction from LA to LV.

  • Murmur: Mid-diastolic rumble with an opening snap.
  • Cause: Rheumatic heart disease is the most common cause.
  • Hemodynamics: ↑ LA pressure, leading to pulmonary hypertension.

⭐ In Aortic Stenosis, a delayed and diminished carotid pulse (pulsus parvus et tardus) is a classic physical exam finding indicating severe disease.

Valvular Regurgitation - Leaky Valves, Backflow Blues

• Pathophysiology: Incompetent valve closure causes blood to leak backward, leading to volume overload in the preceding chamber.
• Cardiac Adaptation:
  • Chamber dilation and eccentric hypertrophy to accommodate ↑ volume.
  • ↑ Preload (↑ EDV) is the primary hemodynamic consequence.
  • Results in ↑ total stroke volume, but ↓ effective (forward) stroke volume.
• Pressure-Volume Loop Changes:
  • Wider loop due to ↑ stroke volume.
  • Rightward shift from ↑ EDV.
  • Loss of true isovolumetric phases as the leaky valve prevents a sealed chamber.

⭐ Aortic regurgitation can cause a "water-hammer" pulse (Corrigan's pulse) and head-bobbing (de Musset's sign) due to the wide pulse pressure.

Heart Failure - Pump Failure, Two Flavors

• Systolic Dysfunction (HFrEF): Reduced Ejection Fraction.

  • Problem: Impaired contractility (can't pump hard enough).
  • Hallmark: EF < 40%.
  • Causes: Ischemic heart disease, dilated cardiomyopathy, myocarditis.
  • Hemodynamics: ↑ End-Diastolic Volume (EDV), ↓ Stroke Volume (SV).
  • P-V Loop: Shifts rightward (↑ volume).

• Diastolic Dysfunction (HFpEF): Preserved Ejection Fraction.

  • Problem: Impaired ventricular relaxation/filling (can't fill enough).
  • Hallmark: EF > 50%.
  • Causes: Chronic hypertension, hypertrophic cardiomyopathy (HCM), restrictive cardiomyopathy.
  • Hemodynamics: ↓ EDV, ↓ SV.
  • P-V Loop: Shifts leftward (↑ pressure).

⭐ High-Yield: S3 heart sound is a classic sign of systolic failure (volume overload), while an S4 heart sound is often heard in diastolic failure (stiff ventricle).

Restrictive & Pericardial Disease - Squeezed & Stiff Hearts

• Core Defect: Impaired diastolic filling from a stiff ventricle (restrictive) or external compression (pericardial), leading to ↓ preload and heart failure signs.

• Restrictive Cardiomyopathy (RCM):

  • Causes: Amyloidosis, sarcoidosis, hemochromatosis.
  • Sound: S3/S4 gallop.
  • Pressure: "Dip-and-plateau" (square root sign) waveform.

• Pericardial Disease:

  • Tamponade: Fluid compresses all chambers.
    • 📌 Beck's Triad: Hypotension, ↑ JVP, Muffled Heart Sounds.
    • Finding: Pulsus paradoxus (inspiratory systolic BP ↓ >10 mmHg).
  • Constrictive Pericarditis: Calcified, rigid pericardium.
    • Sound: Pericardial knock (early diastole).

⭐ Kussmaul's sign (paradoxical ↑ in JVP with inspiration) is a classic finding in constrictive pericarditis, but notably absent in tamponade.

High‑Yield Points - ⚡ Biggest Takeaways

• Aortic stenosis shows a large systolic pressure gradient between the LV and aorta.
• Mitral regurgitation causes a large v-wave in the left atrial pressure tracing.
• Aortic regurgitation results in a widened pulse pressure and loss of the dicrotic notch.
• Mitral stenosis creates a diastolic pressure gradient between the LA and LV.
• Systolic dysfunction features a reduced ejection fraction and an S3 gallop.
• Diastolic dysfunction has a preserved ejection fraction with an S4 gallop.