9.2 Right & Left Heart Hemodynamics

Right & Left Heart Hemodynamics

Procedures 1.A.1 is hemodynamics: the waveforms, the balloon, the pullback, and the shock pattern — not the Gorlin and Fick arithmetic (those calculations are a later chapter). Typical adult numbers in this section are cath-lab teaching ranges, not unpublished ARRT cutoffs.

Quick Answer: A balloon-tipped (Swan-Ganz) catheter records RA (a, x, v, y), then RV, PA, and wedge. Never leave the balloon inflated. A pigtail in the LV and an LV-to-aorta pullback document an aortic stenosis (AS) gradient. Damping or ventricularization of a coronary catheter means the ostium is obstructed — withdraw; do not inject. Cardiogenic shock: high PCWP, low CO. Distributive: low SVR, low PCWP. Tamponade: equalized diastoles.

Right-heart catheterization: balloon-tipped path

A Swan-Ganz catheter is balloon-tipped and flow-directed. From a venous sheath (often internal jugular or femoral), the deflated catheter reaches RA. Inflate in the RA or RV so blood flow carries the balloon through the tricuspid valve, RV, and pulmonic valve into the PA, then into the wedge position. Deflate for PA pressures; inflate briefly for pulmonary-capillary wedge pressure (PCWP).

Never leave the balloon inflated. A persistent wedge is how you infarct a pulmonary segment or rupture a PA. After the wedge number, deflate, confirm a PA waveform returns, and lock the volume syringe so it cannot sit inflated in a pocket.

Watch the screen, not only the marks on the shaft:

• RA: mean typically 2–6 mmHg. a wave = atrial contraction (after the P wave). x descent = atrial relaxation. v wave = atrial filling while the tricuspid valve is closed. y descent = emptying when the tricuspid valve opens. Giant RA v waves suggest tricuspid regurgitation (TR) or a stiff RA/RV.
• RV: typically 20–30 / 0–8 mmHg. Systolic rise, low diastolic, no dicrotic notch. A notch or a high diastolic that matches PA diastolic means you have not arrived, or the tracing is damped.
• PA: typically 20–30 / 4–12 mmHg, mean about 10–18 mmHg. Dicrotic notch from pulmonic closure. Systolic should match RV systolic if there is no pulmonic stenosis.
• PCWP: typically 6–12 mmHg, an LA proxy. Large v waves here are mitral regurgitation (MR) until proven otherwise.

Typical mixed-venous saturations from RA, RV, and PA are about 65–75%.

Left-heart catheterization: pigtail, LVEDP, pullback

A pigtail in the LV records typically 90–140 mmHg systolic and end-diastolic pressure (LVEDP) about 8–12 mmHg. Aortic pressure is typically 90–140 / 60–90 mmHg. Left-heart saturations (LA, LV, aorta) are about 95–100%. Typical CO 4–8 L/min and CI 2.5–4.0 L/min/m² are the flow numbers that make shock profiles make sense.

LV-to-aorta pullback is the AS maneuver: withdraw the pigtail from LV cavity across the valve into the aorta. A systolic LV pressure that remains higher than aortic systolic pressure is the transvalvular gradient. Simultaneous LV and central-aortic (or dual-lumen) recordings refine the same idea. Peak-to-peak versus simultaneous mean gradient is physician language; your job is a clean pullback without damping, an accurate zero at the phlebostatic axis, and a scale that does not clip a 200 mmHg LV systolic pressure.

LVEDP versus PCWP. Both estimate LV filling. They track together when the mitral valve is open and the pulmonary veins are unobstructed. They diverge in MS (PCWP exceeds LVEDP in diastole — that is the mitral gradient) and with giant MR v waves (peak wedge is not LVEDP). Treating a giant v wave as the LVEDP is 40 overstates the true end-diastolic number.

Damping and ventricularization of a coronary catheter

When a diagnostic coronary catheter engages, the displayed pressure should remain a true aortic tracing. Damping: systolic and diastolic fall, the waveform rounds, the dicrotic notch vanishes — the tip is occluding a small or diseased ostium, or the lumen is air or clot. Ventricularization: diastolic pressure collapses toward ventricular diastolic, so a coronary ostium tracing starts to look like LV — classic for a catheter stuffed into a left main or a tight ostial RCA.

Both are stop-injection findings. Withdraw until a crisp aortic waveform returns. A forceful cine through a damped ostium is how diagnostic angiography becomes left-main or RCA dissection. Small RCA ostia damp if the Judkins-right tip is even slightly deep.

Constrictive versus restrictive — teaching waveforms

Both can show a square-root sign (dip-and-plateau) in ventricular diastolic pressure: early diastolic dip, then a plateau as the ventricle cannot fill further.

Constriction (rigid pericardium): diastolic pressures equalize across chambers; ventricular systolic pressures often discordant with respiration in teaching descriptions (LV and RV go opposite directions). Restriction (stiff myocardium): LVEDP often exceeds RVEDP (labs discuss a small gap as a teaching construct — not an ARRT cutoff); systolic pressures more often concordant. Tamponade is the emergency cousin: equalized diastoles, blunted y descent, low stroke volume — not a leisurely square-root seminar. If the patient is crashing, treat tamponade physiology first.

Shock profiles

• Cardiogenic: pump failure. High PCWP, low CO/CI, usually high systemic vascular resistance (SVR). Cool, wet, low mixed-venous saturation.
• Distributive (septic, anaphylactic, vasodilated): low SVR, low or normal PCWP, CO normal or high until the patient decompensates.
• Obstructive tamponade: filling is blocked. Equalized diastolic pressures (RA mean, RVEDP, PA diastolic, PCWP), low CO, hypotension. Volume is a bridge to drainage, not the cure.
• Hypovolemic (for contrast): low PCWP, low CO, high SVR — empty, not congested.

Waveform / landmark / pathology that raises it

Worked case

Balloon-tipped catheter: RA mean 14 mmHg with giant v waves, RV 55/14, PA 55/28 (mean 38), PCWP 26 with v waves to 40, LV 95/26, aorta 95/70, CO 3.1 L/min. The balloon is still inflated after the wedge. Deflate now. This is not distributive shock. High wedge, low CO, and v waves: cardiogenic physiology plus MR (or a very stiff LA). Mean PA is high with a high PCWP — post-capillary pulmonary hypertension, not isolated pulmonary arterial disease. If diastoles later equalize and blood pressure collapses after a perforation, the story has changed to tamponade.

Exam traps

• Leaving the balloon inflated after a wedge.
• Calling every high mean PA pre-capillary without looking at PCWP.
• Injecting through a damped or ventricularized coronary catheter.
• Treating a giant PCWP v wave as LVEDP.
• Calling tamponade distributive because the blood pressure is low.