Cardiac Waveform Interpretation – Key Vocabulary

Overview of “Extra Waveforms” Slides

• Focus: Recognizing and labeling assorted hemodynamic waveforms captured during right‐ and left‐heart catheterization.
• Methodology taught:
  • Always note the pressure scale first (e.g., 0!\to40 vs 0!\to50\;\text{mmHg}) to decide right vs. left heart.
  • Examine morphology (dicrotic notch, amplitude, upstroke/downslope steepness, presence/absence of A or V waves).
  • Use physiologic "normals" as mental templates; deviations hint at pathology.

Slide 1 – Normal Right-Heart Pullback (4 sequential waveforms)

• Pressure scale shown: 0!\to40\;\text{mmHg} → right side of heart.
• Four numbered regions:
  1. Pulmonary Capillary Wedge (PCWP)
  • Balloon inflated; waveform shows A & V waves.
  1. Pulmonary Artery (PA)
  • Balloon deflated; classic PA systolic/diastolic with dicrotic notch.
  1. Right Ventricle (RV)
  • Tall systolic spike, low diastolic nadir ("square‐topped").
  1. Right Atrium (RA)
  • Low‐pressure tracing, visible A & V humps.
• Clinical takeaway: Pullbacks confirm catheter location and allow segmental pressure comparison.

Slide 2 – Simultaneous LV & Wedge (Mitral Stenosis)

• Two traces on same screen (scale 0!\to20 mmHg):
  • LV: Systolic goes off-screen; end‐diastolic pressure (LVEDP) ~12!\text{–}!14 mmHg (normal 7!\text{–}!12).
  • Wedge: Plateau near \approx28!\text{–}!30 mmHg (clearly elevated vs normal 7!\text{–}!12).
• Interpretation path:
  1. Compare LVEDP (normal) to wedge (high).
  2. High PCWP with normal LVEDP ⇒ transmitral gradient ⇒ mitral stenosis.
• Significance: Obstructed valve forces LA to generate higher pressure to fill LV.

Slide 3 – “Mini Wiggers” Diagram (Simultaneous LV, AO, LA)

• Three superimposed waveforms:
  • LV: Tall, sharp systolic upstroke; diastolic downturn.
  • AO: Upper third of screen, blunted peaks; less crisp dicrotic notch.
  • LA / PCWP: Low‐amplitude A & V bumps along baseline.
• Skill objectives:
  1. Identify each trace visually before analysis.
  2. Locate A & V waves on LA line.
     • A wave precedes LV systolic upstroke (atrial kick).
     • V wave peaks during LV systole (atrial filling).
  3. Infer valve events:
     • Mitral valve opens ≈ just after LA V-wave peak.
     • Mitral valve closes immediately after LA A-wave.
     • Aortic valve opens where AO trace diverges upward from LV upstroke.
     • Aortic valve closes near crossover on LV downslope (dicrotic notch).
• Pressure gradients labeled:
  • a: Aortic valve gradient = P{LV{sys}} - P{AO{sys}} (elevated → aortic stenosis).
  • c: Mitral valve gradient = P{LA{mean}} - P{LV{EDP}} (elevated → mitral stenosis).
  • b, d, e: Inert labels (no hemodynamic meaning in this slide).
• Educational analogy: Slide acts as a low‐fidelity Wiggers diagram merging electrical & mechanical events.

Slide 4 – LV & Wedge in Atrial Fibrillation (Mitral Regurgitation)

• Trace characteristics:
  • Rhythm: Irregular baseline → atrial fibrillation; hence no A wave.
  • Large V waves on wedge tracing (~>20 mmHg, normal 7!\text{–}!12).
  • LVEDP ~normal.
• Diagnostic logic: Tall V waves + normal LVEDP ⇒ volume reflux into LA during systole = mitral regurgitation.
• Pathophysiology: Regurgitant jet raises LA pressure each beat, exaggerating V wave.

Slide 5 – Right-Heart Tracing Showing Pulmonic Stenosis

• Scale 0!\to50\;\text{mmHg} → right heart.
• Sequence while catheter is pulled back:
  1. Normal PA waveform: 25/7\text{–}12 mmHg.
  2. RV waveform: Systolic unexpectedly \approx50 mmHg (double PA sys); RVEDP mildly elevated (~10 mmHg).
• Interpretation: RV generates excess pressure to overcome obstructed pulmonic valve, but once flow crosses, PA pressure normalizes ⇒ pulmonic stenosis.

Normal Reference Values (Quick Table‐Look)

• Right Atrium: 2!\text{–}!8 mmHg.
• Right Ventricle: 25/0\text{–}5 mmHg (systolic/EDP).
• Pulmonary Artery (PA): 25/7\text{–}12 mmHg; mean \approx15 mmHg.
• Pulmonary Capillary Wedge (PCWP / LA): 7!\text{–}!12 mmHg; prominent A & V waves.
• Left Ventricle:
  • Systolic 110!\text{–}!130 mmHg (≈ SBP).
  • LVEDP 7!\text{–}!12 mmHg.
• Aorta: Same systolic as LV, slight diastolic difference; clear dicrotic notch.

Pattern-Recognition Heuristics (Instructor Emphasis)

• First glance at pressure scale → localize chamber side.
• Presence of dicrotic notch:
  • High pressure + notch = AO or PA.
  • Absence = ventricular trace.
• A vs V wave identification:
  • A precedes ventricular systole.
  • V occurs during ventricular systole (atrial refill).
• Compare simultaneous tracings when possible to derive valve gradients.

Pathology/Trace Cheat-Sheet (from slides)

• Elevated wedge with normal LVEDP → Mitral Stenosis.
• Giant V waves with absent A waves (AFib) → Mitral Regurgitation.
• AO sys < LV sys → Aortic Stenosis (gradient “a”).
• RV sys ≫ PA sys → Pulmonic Stenosis.

Clinical & Practical Implications

• Accurate waveform interpretation guides valve‐disease diagnosis without immediate imaging.
• Guides decisions on surgical vs percutaneous interventions (e.g., mitral valvuloplasty, TAVR, pulmonic valvotomy).
• Understanding gradients prevents misclassification of pulmonary vs left‐sided etiologies (e.g., distinguishes pulmonary HTN from mitral stenosis).
• Reinforces importance of catheter pullback maneuvers and simultaneous recording for quality assurance.

Ethical / Safety Reminders Mentioned or Implied

• Correct catheter placement avoids ventricular perforation or arrhythmias.
• Continuous waveform scrutiny prevents misinterpretation that could lead to incorrect therapy (e.g., unnecessary vasodilators in pulmonic stenosis).
• Ensure ECG leads are displayed when possible to synchronize electrical-mechanical events.

Key Take-Home Equations & Mnemonics

• Valve gradient: \Delta P = P{proximal} - P{distal}.
• Remember “A before C-contraction, V while Ventricle squeezes” for LA trace.
• Pulmonic stenosis hint: “High RV, normal PA → obstruction at valve.”

End of Waveform Section ‑ Instructor’s Closing

• The set concludes the waveform-interpretation module.
• Encouraged to practice tracing overlays & pullback sequences to solidify chamber recognition.