What is a right heart catheterization?

What is Right Heart Catheterization?

Right heart catheterization (RHC) is a minimally invasive diagnostic procedure in which a catheter is inserted through a vein (typically the internal jugular or femoral vein) and advanced into the right side of the heart and pulmonary arteries to directly measure intracardiac pressures, pulmonary artery pressures, cardiac output, and obtain blood samples for oxygen saturation analysis. 1, 2

Core Purpose and Measurements

RHC serves as the gold standard for hemodynamic assessment of the cardiovascular system, providing direct and accurate measurements that cannot be reliably obtained through non-invasive methods 3, 2, 4. The procedure allows clinicians to:

• Record right atrial pressure, right ventricular pressure, pulmonary artery pressure (systolic, diastolic, and mean), and pulmonary artery wedge pressure (which reflects left ventricular filling pressure) 1, 5
• Measure cardiac output through thermodilution technique, where a known volume and temperature of fluid is injected into the right atrium and temperature change is measured downstream in the pulmonary artery 5
• Obtain blood samples from different cardiac chambers to assess oxygen saturation and detect intracardiac shunts 1
• Perform pulmonary angiography when contrast material is injected to visualize the pulmonary vasculature 1

Calculated Hemodynamic Parameters

From the direct measurements, critical derived parameters are calculated to guide clinical decision-making:

• Pulmonary vascular resistance (PVR), systemic vascular resistance, and transpulmonary gradient 6, 5
• Cardiac power output (calculated as: cardiac output × mean arterial pressure ÷ 451) 5
• Pulmonary artery pulsatility index and right ventricular stroke work index 5

Primary Clinical Indications

Pulmonary Hypertension Diagnosis (Most Critical Indication)

RHC is mandatory to confirm the diagnosis of pulmonary arterial hypertension (PAH) before initiating any PAH-specific therapies - echocardiography alone is insufficient and should never be relied upon solely for diagnosis 7. The procedure must be performed at expert centers due to technical complexity 7.

Key hemodynamic definitions established during RHC:

• Pulmonary hypertension: mean PA pressure >20 mmHg 7
• Pulmonary arterial hypertension: mean PA pressure >20 mmHg AND wedge pressure ≤15 mmHg AND PVR ≥3 Wood units 7

Heart Failure Management

RHC is indicated when 7:

• Persistent symptoms despite empiric therapy AND clinical assessment cannot determine the underlying hemodynamic problem (fluid status, perfusion, or vascular resistance)
• Systolic pressure remains low or symptomatic despite initial therapy
• Renal function worsens with diuretic therapy and it's unclear if this reflects inadequate perfusion versus overdiuresis
• Presumed cardiogenic shock requiring escalating pressor therapy, particularly when considering mechanical circulatory support devices

Other Key Indications

• Assessment for cardiac transplantation - RHC is mandatory when organ transplantation is being considered in patients with PH due to left heart disease or lung disease 6, 7
• Chronic thromboembolic pulmonary hypertension (CTEPH) - required to confirm diagnosis and guide treatment decisions including surgical candidacy 7
• Congenital cardiac shunts - necessary to assess pulmonary vascular resistance and shunt hemodynamics to support surgical correction decisions 7
• Severe valvular disease - may be reasonable to guide therapy in patients with severe mitral regurgitation, severe tricuspid regurgitation, and severe pulmonary arterial hypertension when symptoms persist or hemodynamics cannot be adequately assessed non-invasively 5

Procedural Technique

Vascular Access

The right internal jugular vein is the preferred approach, used in approximately 89% of procedures 8. Alternative access sites include the femoral vein and subclavian vein 1.

Transseptal Approach

When access to the left side of the heart is needed and no preexisting communication exists, an atrial transseptal puncture from the right atrium into the left atrium provides direct access 6. This approach:

• Reduces potential arterial compromise compared to retrograde arterial studies 6
• Provides higher fidelity atrial pressure waveforms for optimal assessment of mitral valve disease 6
• Allows use of smaller-diameter catheters if retrograde study is subsequently needed 6

Vasoreactivity Testing

Vasoreactivity testing is indicated ONLY in expert centers and ONLY for patients with idiopathic PAH, heritable PAH, or drug-induced PAH to identify candidates for high-dose calcium channel blocker therapy 7.

• Nitric oxide is the recommended agent for performing vasoreactivity testing 7
• A positive response is defined as: reduction of mean PAP ≥10 mmHg to reach an absolute value ≤40 mmHg with increased or unchanged cardiac output 7

Safety Profile and Complications

RHC is generally safe when performed by experienced operators, with a mortality rate of 0.1-0.2% in elective cases 1. However, complication rates are higher in specific populations 1:

• Patients with severe left ventricular dysfunction
• Neonates and elderly patients
• Those with severe arterial hypoxemia or pulmonary hypertension

Most Common Complications

Based on contemporary practice data, complications occur in approximately 3.9% of procedures 8:

Access site-related complications 3, 8:

• Carotid artery injury (most common access site complication)
• Arteriovenous fistula formation
• Incidental artery puncture (1.1%)
• Local hematoma (2.2%)
• Pneumothorax (0.2%)

Catheter-related complications 3, 8:

• Tricuspid valve injury (most common catheter-related complication)
• Atrial arrhythmias (0.2%)
• Superior vena cava dissection (0.2%)
• Pulmonary artery rupture (rare but potentially fatal)
• Pulmonary edema (0.2%)
• Venous thrombosis and pulmonary embolism

Pre-Procedure Requirements

Patient Assessment

Physicians must thoroughly review the patient's history, physical examination, and laboratory data before the procedure, ideally the day before, to assess bleeding risk and kidney function 1. All patients should be evaluated for:

• Bleeding risk - particularly important for anticoagulation management 1
• Kidney function - for patients with chronic kidney disease, contrast media volume should be minimized 1

Informed Consent

Informed consent must be obtained by the physician performing the procedure, with detailed discussion of reasons, benefits, complications, and procedure description 1.

Anticoagulation Management

• Patients on oral anticoagulants: management depends on the type of anticoagulant 1
• Patients already on daily aspirin therapy: should take 81-325 mg before the procedure 1
• Patients not on aspirin therapy: should be given non-enteric aspirin 325 mg before the procedure 1

Post-Procedure Care

Standard post-procedural orders should include checking and recording vital signs, distal pulses, and bandage sites every 15-30 minutes for 2 hours, then hourly 1.

Limitations and Considerations

• Measurements reflect only resting, supine conditions - exercise or stress hemodynamics are not captured 7, 5
• Spontaneous variability in pulmonary artery pressure can be ±20 mmHg even without intervention 7
• Accuracy can be affected by: tricuspid regurgitation, positive end-expiratory pressure ventilation, and catheter position 5
• Not recommended for routine use in noncardiac surgery or in all heart failure patients 5

Critical Pitfalls to Avoid

• Never perform RHC outside expert centers for pulmonary hypertension evaluation - this is technically demanding and associated with serious complications when performed by inexperienced operators 7
• Never rely on echocardiography alone to diagnose PAH - RHC confirmation is mandatory before initiating PAH-specific therapies 7
• Avoid ambulatory catheterization in patients with NYHA class III-IV heart failure, severe pulmonary hypertension, or suspected active endocarditis 7
• Inadequate hydration before contrast administration increases the risk of contrast-induced nephropathy 1
• Each catheterization laboratory should maintain a prospective registry of complications to monitor performance 1