Right Heart Catheterization

1. Right Heart Catheterization Sripal Bangalore, M.D., M.H.A. and Deepak L. Bhatt, M.D., M.P.H., F.A.H.A

2. Overview Right Heart Catheterization (RHC) • Indications • Contraindications / Caution • Equipment • Technique • Precautions • Cardiac Cycle • Pressure monitoring • Zeroing and Referencing • Fast flush test/ Square wave test • Pressure wave interpretation • Cardiac output • Derived measurements

3. Indications • No universally accepted indication as right heart (pulmonary artery, PA) catheterization has not been shown to improve outcomes1 • However it is useful in the following diagnostic and therapeutic applications • Diagnostic • Differentiation of various etiologies of shock and pulmonary edema • Evaluation of pulmonary hypertension • Differentiation of pericardial tamponade from constrictive pericarditis and restrictive cardiomyopathy • Diagnosis of left to right intracardiac shunts • Therapeutic • Guide to fluid management and hemodynamic monitoring of patients after surgery, complicated myocardial infarction, patients in shock, heart failure, etc. 1Sandham JD et al. A randomized, controlled trial of the use of pulmonary-artery catheters in high-risk surgical patients. N Engl J Med 2003;348(1):5-14

4. Contraindications / Caution • No absolute contraindications for use of PA catheter. Extreme care needed particularly in patients with severe pulmonary hypertension and in the elderly • Fluoroscopic guidance recommended in patients with pre-existing left bundle branch block (risk of complete heart block if right bundle damaged during catheter insertion)

5. Equipment • 2% chlorhexidine skin prep • Sterile gown, gloves, hat and mask • Sterile drape • 2% lidocaine solution for local anesthesia • Micropuncture needle and sheath (optional) • Sterile ultrasound probe cover and gel • Introducer sheath and needle • Pulmonary artery (Swan-Ganz) catheter • Sterile flush • Pressure tubing, transducer and monitor

6. Equipment Pulmonary Artery (Swan-Ganz) Catheter These are 7F to 7.5F system catheters and are available as femoral vein insertion to continuous cardiac output catheters Balloon inflation valve Balloon inflation syringe Distal PA lumen hub VIP lumen hub Proximal injectate lumen hub Thermistor connector Reproduced with permission from Edward Lifesciences, Irvine, California

7. Technique- Micropuncture • Insertion site: Internal jugular vein, subclavian vein, antecubital vein, or femoral vein • After the site is prepped and draped, local anesthesia is administered at the site by giving 5 to 10 cc (depending on the site) of 2% lidocaine using a 25G needle • Vein entered using a needle (preferably micropuncture) and preferably under ultrasound guidance (especially for internal jugular vein) • After ensuring that the needle is indeed in a vein (dark, non-pulsatile flow or checking pressure or oxygen saturation), the guidewire is introduced into the micropuncture needle and the needle exchanged for a micropuncture sheath • If there is difficulty in wiring and the micropuncture wire needs to be removed, remove both the needle and the wire as a unit • Attempting to remove just the guidewire can result in the guidewire tip shearing off the needle tip with subsequent guidewire embolization • Exchange the micropuncture catheter for the introducer sheath

8. Technique Preparing the catheter • Under sterile conditions, remove the pulmonary artery catheter from the packaging • Flush the proximal and distal ports with saline to ensure an air free system and place stopcocks on the ends • Fill the balloon inflation syringe with 1.5 cc of air and inflate the balloon under saline to ensure no air leaks in the balloon • Prepare the pressure monitoring system for use according to institutional practice, ensuring an air free system

9. Technique Inserting the catheter • The pulmonary artery (PA) catheter can be inserted either under fluoroscopic guidance (preferred) or under the guidance of the pressure wave forms • Fluoroscopic guidance is recommended in patients with markedly enlarged RA or RV, severe tricuspid regurgitation, or in those with left bundle branch block • A PA catheter with the balloon inflated is designed to be flow-directed and will follow the direction of blood flow (right atrium to pulmonary arteries) • The catheter should be advanced to the vena cava/RA junction, the approximate distance (as measured on the PA catheter) from the site insertion is below RA = right atrium

10. Technique Inserting the catheter • Once the catheter tip reaches the junction of the vena cava and right atrium, the balloon is inflated with 1.5 cc of air and the pressure waveforms noted • The following sequential waveforms will be noted as the catheter passes through the cardiac chambers • Right atrial (RA) waveform • Right ventricular (RV) waveform a a a v v v c c c x x x y y y

11. Technique Inserting the catheter • Pulmonary artery (PA) pressure waveform • Pulmonary capillary wedge pressure (PCWP) waveform • Similar to RA pressure waveform except slightly higher • Normal insertion tracing will therefore appear as below • For RV to PA - observe changes in diastolic pressure (increase) as the systolic pressure stays the same a a a v v v c c c x x x y y y a v c x y

12. Technique Inserting the catheter • Once a PCWP tracing is seen, deflate the balloon • The catheter should be withdrawn 1-2 cm to remove any redundant length or loop in the RA or RV. Keep the tip in a position where full or near full inflation volume is necessary to produce a wedge tracing • The balloon should be deflated and the pressure wave form seen should now be that of the PA. If still the PCWP, it is likely that the catheter is distal and should be retracted until a PA pressure tracing is seen • The ideal position of the catheter is the zone 3 region of the lung (lower zone) • For subsequent wedge tracings, the balloon should be inflated with the minimum amount of air to produce a wedge tracing. Excess can cause “overwedging” where the PCWP will be higher due to transmittal of pressure from the balloon and with loss of characteristic waveforms Removing the catheter • The catheter should always be removed with the balloon deflated to avoid damaging the valves

13. Technique Precaution • Always advance the catheter with the balloon inflated (catheter is flow-directed, also reduces ventricular irritability and ectopy) • Never leave the catheter wedged in the PA for longer than necessary, to avoid the risk of pulmonary artery rupture/pulmonary infarction • Do not overinflate the balloon • If wedge is obtained at volumes <1.0cc, pull the catheter back to a position where full or near-full inflation volume (1.0 to 1.5cc) produces a wedge tracing • Before balloon reinflation, always check the waveform to ensure no distal migration • Never withdraw the catheter with the balloon inflated to avoid valvular damage • Never use fluids (saline) to inflate the balloon • In situations where multiple attempts at advancing the catheter to the PA fail, a 0.025” guidewire can be used under fluoroscopic guidance to help advance the catheter to the PA • Always maintain catheter tip in a main branch of the PA • If performed via the internal jugular or the subclavian vein route and without fluoroscopic guidance, chest x-ray should be obtained post procedure to rule out pneumothorax and to verify catheter position • Never flush catheter with balloon wedged in the PA

14. Time (msec)  0 100 200 300 400 500 600 700 800 QRS Complex Cardiac Cycle EKG T P P Left Sided Pressures 120 Aorta 90 Dicrotic Notch Pressure (mm Hg) 60 Left Ventricular Pressure 30 v c Left Atrial Pressure a y x 0 Atrial Systole Ventricular Systole Ventricular Diastole

15. Time (msec)  0 100 200 300 400 500 600 700 800 QRS Complex Cardiac Cycle EKG T P P Right Sided Pressures 30 PA Pressure Dicrotic Notch Pressure (mm Hg) 15 Right Ventricular Pressure v c Right Atrial Pressure a y x 0 Atrial Systole Ventricular Systole Ventricular Diastole

16. Pressure Recordings • Always record pressure at end expiration (except in patients on PEEP) • Under normal conditions, pressures will be lower in inspiration due to decrease in intrathoracic pressure • Before any pressure measurements are taken, it is imperative to perform zeroing and referencing of the system • Zeroing- accomplished by opening the system to air so as to equilibrate with atmospheric pressure • Referencing- accomplished by ensuring that the air-fluid interface of the transducer is at the level of the patient heart (phlebostatic axis) (4th intercostal space midway between anterior and posterior chest wall) • For every inch the heart is offset from the reference point of the transducer, a 2mm Hg of error will be introduced. If the heart is lower than the transducer, the pressure will be erroneously low and if the heart is higher, the pressure will be erroneously high. • Fast flush test/ Square wave testing • The dynamic response of the pressure monitoring system is determined by measuring the resonant frequency and the damping coefficient of the system using the fast flush test

17. Pressure Recordings Optimal Damping Fast flush test / Square wave testing • Performed by briefly opening and closing the valve in the continuous flush device • This produces a square ware pattern on the oscilloscope, an initial steep rise followed by a plateau, followed by steep fall below baseline which is then followed by oscillations. The pattern determines optimal versus suboptimal damping • Optimal damping- usually 1.5 to 2 oscillations before returning to baseline. This is ideal • Over damping- None to <1.5 oscillations before retuning to baseline. Common cause - air bubbles. Underestimation of systolic pressure. Diastolic pressure may not be affected • Under damping- >2 oscillations before returning to baseline. Common cause - excessive tube length, multiple stopcocks in the circuit, etc. Overestimated systolic pressure and underestimated diastolic pressure Over Damping Under Damping

18. Pressure Recordings • Always record pressure at end expiration (except in patients on PEEP) • Under normal conditions, pressures will be lower in inspiration due to decrease in intrathoracic pressure • PCWP reflects left atrial pressure and hence the left ventricular end diastolic pressure as long as ventricular compliance is normal or unchanging • PCWP > LVEDP: Mitral valve stenosis or regurgitation, left atrial myxoma, pulmonary vascular disease/embolism, increased pulmonary vascular resistance, cor pulmonale • PCWP < LVEDP: Early stages of diastolic dysfunction, aortic regurgitation, decreased ventricular compliance due to myocardial ischemia/infarction, positive pressure ventilation, etc. PCWP = Pulmonary Capillary Wedge Pressure

19. Pressure Wave Interpretations RA/ PCWP AVNRT = Atrioventricular Nodal Reentry Tachycardia; VSD = Ventricular Septal Defect

20. Cardiac Output • Three indirect methods for cardiac output determinations • Dye indicator dilution technique • Fick’s technique • Cardiac Output = Oxygen consumption in ml/min • A-V Oxygen difference • Oxygen consumption measured using an oxygen hood • Normal oxygen consumption is 250 ml/min • A-V Oxygen difference = 13.4 x Hgb concentration x (SaO2-SvO2) • Most accurate in low output states and is considered the gold standard • Thermodilution technique • Known amount of solution (usually saline) is injected into the proximal port (right atrium) and mixes and cools the blood which is recorded by a thermistor located at the distal end of the catheter

21. Cardiac Output • Thermodilution technique • CO is inversely proportional to the area under the curve • Not reliable in patients with severe tricuspid or pulmonic valve regurgitation. Results in lower peak and a prolonged washout phase due to re-circulation resulting in underestimation of CO • Not reliable in patients with intra-cardiac shunts. Overestimates CO • Normal CO = 4 - 8L/min • Normal cardiac index (cardiac output indexed to body surface area) = 2.5 - 4.0 L/min/m2 • Oxygen saturation (SO2) obtained from the PA is a rough measure of CO • PA SO2 >80  High CO (shunt, sepsis, etc.) • PA SO2 65-80  Normal CO • PA SO2 <65  Low CO

22. Derived Parameters • Vascular resistance obtained is least accurate and most sensitive to minor inaccuracies in data acquisition CO = Cardiac Output; DFP = Diastolic Filling Period; HR = Heart Rate; LVEDP = Left Ventricular End Diastolic Pressure; MAP = Mean Arterial Pressure; MPAP = Mean Pulmonary Artery Pressure; MvO2 = Oxygen saturation mixed venous; PaO2 = Oxygen saturation pulmonary artery; PCWP = Pulmonary Capillary Wedge Pressure; PvO2 = Oxygen saturation pulmonary veins; RAP = Right Atrial Pressure; SaO2 = Oxygen saturation arterial; SEP = Systolic Ejection Period; SVI = Stroke Volume Index.

23. Constriction vs. Restriction • Hemodynamic parameters that help differentiate constrictive pericarditis versus restrictive cardiomyopathy LVEDP = Left Ventricular End Diastolic Pressure; PCWP = Pulmonary Capillary Wedge Pressure; RA = Right Atrial; RVEDP = Right Ventricular End Diastolic Pressure; RVSP = Right Ventricular Systolic Pressure.