Right Heart Catheterization
Madison James
Pulmonary artery catheter (PAC) AKA Swan-Ganz catheter: Multi-lumen catheter that sits in the right heart to provide invasive measurement of hemodynamic parameters.
Indications for PAC Placement
Unexplained/unknown volume status in shock, severe cardiogenic shock (ex: acute valvular disease, pericardial tamponade), suspected/known pulmonary artery hypertension, severe underlying cardiopulmonary disease (ex: congenital heart disease, L to R shunt, severe valvular disease, pulmonary hypertension) undergoing corrective or other surgery.
Contraindications to PAC placement
- Infection at the insertion site
- RA/RV mass or thrombi
- Right-sided endocarditis or infected endocardial mass
- Mechanical tricuspid or pulmonic valves
- Presence of RV assist device.
Complications of PAC placement
- Arrhythmias: Ectopy, VT, RBBB; complete heart block if preexisting LBBB
- Infection: Bacteremia; rare endocarditis (including pulmonic valve)
- Thromboembolic: Venous thrombosis, PE, pulmonary infarction
- Venous access: Pneumothorax, bleeding, air embolism
- Pulmonary artery perforation/rupture (most feared complication)
- Endocardial/valvular injury: Trauma, inflammation, or damage to tricuspid/pulmonic valves.
PAC Pressure Tracings
| Definition | Normal "Rule of 5s" | Interpretation | |
|---|---|---|---|
| Central Venous Pressure (CVP) / Right Atrial Pressure (RAP) | Mean pressure in right atrium or SVC; reflects right ventricular preload (indicator of volume status) | 0 - 5 mmHg |
Elevated CVP/RAP: RV dysfunction, tricuspid regurgitation, pulmonary
hypertension, volume overload Low CVP/RAP: hypovolemia |
| Right Ventricle Pressure (RVP) | Peak systolic* and end-diastolic pressures in RV | 25 / 5 mmHg |
Elevated Systolic RVP: Pulmonary HTN, pulmonic stenosis, or PE Elevated Diastolic RVP: RV dysfunction, cardiac tamponade/constriction |
| Pulmonary Artery Pressure (PAP) | Systolic, end-diastolic, and mean pressures in pulmonary artery |
25 / 10 mmHg Mean (mPAP): 15 mmHg |
Elevated mPAP (>22 mmHg): - Acute: PE, hypoxemic-induced pulmonary vasoconstriction - Chronic: Group 1-5 pulmonary hypertension (mPAP > 20 mmHg for diagnosis) |
| Pulmonary Artery Wedge Pressure (PAWP/PCWP) | Estimates left atrial pressures and LVEDP – obtained by inflating balloon in PA | 10 mmHg | Elevated PAWP (>15 mmHg): LVHF, mitral and aortic valve disease, hypervolemia, R-to-L shunts, constrictive/restrictive CM, hypertrophic CM |
|
Thermodilution Cardiac Output & Cardiac Index *Preferred method of CO measurement when VO2 unavailable* |
CO = amount of blood pumped in one min. CI = cardiac output divided by body surface area (to standardize for body size) |
CO: 4-8 L/min CI: 2.5-4.0 L/min/m2 |
Low CI: systolic/diastolic heart failure, severe valvular disorder,
RV failure, pHTN, cardiogenic shock. Elevated CI (high-output states): sepsis, severe anemia, thyrotoxicosis, AV shunt |
| Mixed venous oxyhemoglobin saturation (SvO2) | O2 saturation of blood in pulmonary artery, reflects balance between systemic O2 delivery and O2 consumption | 65-75% |
High SvO2 (>75%): reduced tissue O2 extraction
(ex: sepsis, L-to-R shunt, high CO state) Low SvO2 (<65%): inadequate O2 delivery related to demand due to increased tissue O2 extraction (ex: low CO, anemia, hypoxemia) |
| * RVSP can be a surrogate for PASP in absence of RVOT | |||
Calculating Hemodynamic Parameters from PAC Pressures
| Definition | Normal Values | Interpretation | |
|---|---|---|---|
|
Fick Method CO and CI
*Direct Fick = Gold Standard* |
Calculated CO based on tissue O2 consumption (VO2) and O2 concentrations in arterial and venous blood |
CO: 4-8 L/min
CI: 2.5-4.0 L/min/m² |
See "Cardiac Output and Index" above. |
| Systemic Vascular Resistance (SVR) | Resistance of blood flow in systemic circulation, representing LV afterload; helpful in delineating the etiology of shock and effect of afterload reduction in HF management | 900-1200 dynes*sec*cm-5 |
Elevated SVR (vasoconstriction): hypovolemic, cardiogenic, & obstructive shock
Decreased SVR (vasodilation): distributive shock (sepsis, anaphylaxis, neurogenic) |
| Transpulmonary Gradient (TPG) |
Pressure difference across pulmonary vasculature; used to distinguish
passive and reactive pHTN
TPG = mPAP-PCWP |
≤12 mmHg | TPG > 12 mmHg suggests component of the pHTN is secondary to pulmonary vascular remodeling (pre- and post-capillary pHTN) |
| Pulmonary Vascular Resistance (PVR) |
Resistance to blood flow through pulmonary circulation
PVR = (TPG / CO) PVR used with PAWP to classify pulmonary hypertension into three phenotypes |
0.3-2.0 Wood Units (WU)
or <160 dynes*sec*cm-5
1 WU = 80 dynes*sec*cm-5 |
Elevated PVR (≥3 WU): historically defined pulmonary arterial
hypertension, suggests combined pre-and post-capillary pHTN
PVR 2.2-2.9 WU: borderline elevation associated with increased mortality risk |
| Pulmonary Artery Pulsatility Index (PAPi) |
Estimates RV pulsatile function and contractile reserve;
indicator of RV function
PAPi = (sPAP − dPAP) / RAP |
>2.0 |
Low PAPi (<1.85-2.0) predicts RV failure after LVAD implantation;
associated with worse outcomes in cardiogenic shock and acute inferior MI
PAPi <1.0 associated with increased mortality and need for RV mechanical circulatory support |
| Cardiac Power Output (CPO) |
Rate of energy output of heart
CPO = (MAP-RAP) × Cardiac Output / 451 Strong predictor of mortality in patients with advanced HF and cardiogenic shock |
> 1.0 Watts | CPO < 0.6 W associated with poor outcomes in acute MI-related cardiogenic shock and reduced likelihood of survival after mechanical circulatory support weaning |