Right Heart Catheterization
Contents. #Introduction · #Definition · #Key Concepts · #Measurement and Pitfalls · #Haemodynamic Interpretation · #Clinical Applications · #Contradictions / Open Questions · #Connections · #Sources
Detailed pages. concepts/RHC-Technique-and-Measurement · concepts/RHC-Haemodynamic-Interpretation · concepts/RHC-Clinical-Applications
Introduction
Right heart catheterisation is the reference method for measuring pulmonary pressures and cardiac output, and the procedure on which the diagnosis of pulmonary hypertension, the phenotyping of heart failure and the assessment of transplant and LVAD candidacy all rest.
- It answers four questions: what the filling pressures are, what the output is, whether the pulmonary circulation is diseased, and whether the right ventricle can keep up.
- Two numbers carry most of the decisions — the wedge pressure and the cardiac output. Every classification in the wiki's haemodynamic pages is a grid of those two against a threshold.
- A number is only as good as its acquisition. Zero reference, respiratory phase, waveform timing and the method chosen for output each move the result, and the wedge pressure absorbs more of that error than anything else measured.
- It is safe in experienced hands — about 1.1% serious adverse events and 0.055% procedure-related mortality — but pulmonary artery perforation is the complication that defines the risk.
- It earns its place where examination fails. In heart-failure cardiogenic shock the derangement can be extreme while lactate and organ function remain normal; in HFpEF the resting value is often normal and only provocation reveals the diagnosis.
- It is contested at the margins. Whether routine catheterisation helps in chronic heart failure, and whether doing it early in shock changes outcome, are both open — and the guidelines answer the first question differently.
Abbreviations: AF, atrial fibrillation; CAV, cardiac allograft vasculopathy; CI, cardiac index; CO, cardiac output; CPO, cardiac power output; CVP, central venous pressure; DPG, diastolic pressure gradient; HFpEF, heart failure with preserved ejection fraction; HF-CS, heart-failure cardiogenic shock; ISHLT, International Society for Heart and Lung Transplantation; LVAD, left ventricular assist device; LVEDP, left ventricular end-diastolic pressure; MAP, mean arterial pressure; mPAP, mean pulmonary artery pressure; MVO₂, mixed venous oxygen saturation; PAH, pulmonary arterial hypertension; PAPI, pulmonary artery pulsatility index; PAWP, pulmonary artery wedge pressure; PCWP, pulmonary capillary wedge pressure; PH, pulmonary hypertension; PVR, pulmonary vascular resistance; RAP, right atrial pressure; RHC, right heart catheterisation; RV, right ventricular; RVSWI, right ventricular stroke work index; SCAI, Society for Cardiovascular Angiography and Interventions; SVRI, systemic vascular resistance index; TPG, transpulmonary gradient; WU, Wood units.
Definition
Right heart catheterisation is an invasive haemodynamic procedure using a balloon-tipped, flow-directed pulmonary artery catheter — introduced by Swan and Ganz in 1970 — to measure intracardiac and pulmonary pressures and cardiac output directly. It is the gold standard for diagnosing and classifying pulmonary hypertension and is used across the heart failure spectrum, from ambulatory chronic heart failure through cardiogenic shock to LVAD candidacy and transplantation assessment.
The measurements it produces are interdependent: the pressures classify the pulmonary circulation, the output normalises them into resistance, and the right atrial pressure describes the ventricle that has to tolerate whatever is done next. Interpretation therefore always reads the set, never a single value.
Key Concepts
- Every haemodynamic diagnosis is a two-axis plot. Pulmonary hypertension is wedge against resistance; shock is index against wedge; transplant candidacy is gradient and resistance against a provoked response. Learning the axes is what makes the numbers portable between contexts.
- The right ventricle is the limiting organ in advanced therapy. Before transplantation and LVAD implantation the questions are whether the right ventricle can accept a normal pulmonary vascular resistance and whether it can drive a mechanical pump — which is why right atrial pressure and its ratio to wedge recur throughout the applications.
- A resting measurement at the boundary is the least useful one. The wedge pressure between 12 and 18 mmHg is the zone where HFpEF hides, and the answer is provocation rather than repeated rest studies.
- Trend beats a single value. Diuresis, volume state, sedation and posture all shift the numbers; a study performed in decompensation describes decompensation, not the patient.
- The measurement itself is the first source of error. Most of the contradictions in this cluster are about technique and thresholds rather than about physiology.
Measurement and Pitfalls
Full detail: concepts/RHC-Technique-and-Measurement.
This spoke covers access, patient position, zero reference, the respiratory cycle, cardiac output methods, wedge-pressure technique, shunt detection and the safety profile — and carries the reference table of normal values with the discrepancies between sources left visible.
- Wedge pressure is read at end-diastole, with separate rules for atrial fibrillation and for large V-waves, and confirmed by oximetry within 3–5% of systemic saturation.
- Direct Fick is the reference output method and the least available; indirect Fick is confirmed inaccurate; thermodilution is the working default and is invalid in shunts and on ECMO.
- Serious adverse events occur in about 1.1%, with pulmonary artery perforation the feared complication.
Haemodynamic Interpretation
Full detail: concepts/RHC-Haemodynamic-Interpretation.
This spoke covers the thresholds — the 13 mmHg upper limit of normal against the 15 mmHg diagnostic boundary, and the 12–18 mmHg zone of uncertainty — together with fluid challenge, passive leg raise, exercise testing and the four invasive criteria for HFpEF.
- A wedge pressure of 19 mmHg or more after a fluid bolus or leg raise identifies occult post-capillary physiology; 11 mmHg or less rules it out.
- Exercise phenotypes — chronotropic incompetence, preload insufficiency, wedge indexed to workload — describe why a patient is limited, and have not yet yielded therapies that work.
- Vasodilator challenge before transplantation and acute vasoreactivity testing in pulmonary arterial hypertension use the same drugs for opposite purposes and are routinely conflated.
Clinical Applications
Full detail: concepts/RHC-Clinical-Applications.
This spoke covers chronic and acute heart failure, cardiogenic shock, valvular disease, transplantation, LVAD candidacy and ramp studies, portal hypertension, high-output failure and remote pressure monitoring.
- In chronic heart failure the haemodynamic phenotype is a combination of pulmonary pressure, wedge, right atrial pressure and resistance, not a single value.
- Cardiogenic shock is staged by wedge and index; heart-failure shock can be haemodynamically more extreme than infarct shock while lactate remains normal.
- Before transplantation, a systolic pulmonary artery pressure of 50 mmHg or more with a gradient of 15 mmHg or a resistance of 3 WU triggers a vasodilator challenge.
- After LVAD implantation, a right atrial pressure above 15 mmHg with a ratio to wedge above 0.63 predicts right ventricular failure, with one-year survival of 59% against 78%.
Contradictions / Open Questions
- No single wedge-pressure threshold is agreed. Physiology sets the upper limit of normal at 13 mmHg, pulmonary hypertension guidelines set post-capillary physiology at above 15, the volume-challenge literature moved from 18 to 19, and Diamond–Forrester still splits wet from dry at 18. Each spoke quotes its own source faithfully; a reader crossing between them meets a different number for the same measurement. This is the cluster's largest structural problem, and no consensus statement resolves it.
- Absolute pressures and flow-normalised slopes disagree. A peak exercise wedge of 25 mmHg and a wedge-to-output slope above 2 mmHg·L·min identify different patients in about a fifth of cases, with different output profiles. The slope discriminates better across postures but has no standardised threshold.
- Cardiac output is measured, not known. Direct Fick needs equipment most laboratories lack, indirect Fick is inaccurate, and thermodilution's accuracy in significant tricuspid regurgitation is disputed. Because resistance is output divided into a gradient, every such error becomes a diagnostic error downstream.
- ESC and AHA disagree on routine catheterisation in chronic heart failure. ESC permits it as Class 2b in selected patients; AHA calls routine use Class 3. The same patient is a reasonable candidate in one system and an unjustified procedure in the other.
- Early catheterisation in cardiogenic shock is supported by cohort data only. Less kidney injury and more mechanical support in 46,963 patients, with the randomised trial still running.
- Vasodilator testing before transplantation predicts a number, not a survival benefit. Resistance falling below 2.5 WU has been associated with improved survival in one study and with no advantage in another, and no absolute cut-off is endorsed.
- Advanced metrics are prognostic but not adopted. The pulsatility index, cardiac power output and stroke work index all predict outcome and none is integrated into European shock staging.
- The acute heart failure classification overlaps with itself. A wedge of 16 mmHg with a raised right atrial pressure and a low index satisfies both the isolated right ventricular and the biventricular phenotypes.
- Remote pressure monitoring has stronger trial evidence than its guideline class. Four trials show hospitalisation reduction while the strategy sits at ESC Class 2b.
Connections
- concepts/RHC-Technique-and-Measurement — access, zeroing, output methods and the reference table
- concepts/RHC-Haemodynamic-Interpretation — thresholds, provocation and exercise testing
- concepts/RHC-Clinical-Applications — disease-specific application and decision rules
- concepts/Cardiac-Output-Measurement — method comparison and sources of output error
- concepts/Pulmonary-Hypertension — the diagnostic framework the pressures feed
- concepts/PAH-Treatment — what vasoreactivity means therapeutically
- entities/Heart-Failure and entities/HFpEF — the syndromes being phenotyped
- concepts/Cardiogenic-Shock — SCAI staging, support and weaning
- concepts/Right-Ventricular-Failure — the chamber that limits advanced therapy
- concepts/Pulmonary-Artery-Pulsatility-Index and concepts/RV-PA-Coupling — the indices built from these measurements
- concepts/Constrictive-vs-Restrictive — the haemodynamic differentiation the ratio begins
- concepts/Intracardiac-Shunts — oximetry runs and shunt calculation
- concepts/Aortic-Stenosis — the valve lesion where the catheter arbitrates
- concepts/Cardiorenal-Syndrome — congestion and renal function
Sources
Heart failure, shock and transplantation
Haemodynamic technique and measurement
Pulmonary hypertension