Right heart catheterization

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Right heart catheterization

Introduction

Right heart catheterization (or pulmonary artery catheterization) provides information about hemodynamics of the circulation. An important goal is precise assessment of pressure waves generated by the different cardiac chambers. It is used to differentiate forms of shock (cardiac vs non-cardiac) and measurement of cardiac output in the ICU, and monitor the effect of inotropic and vasopressive medication. In the cathlab it is used to differentiate origin of pulmonary hypertension (primary vs secondary), as assessment of valve abnormalities, cardiac shunts and tamponade. Simultaneous measurement of left and right sided pressures can be used to precisely determine whether constrictive pericarditis is present.

It was once common to perform a right heart catheterization in every patient that came into the cathlab. The use of it has fallen because nowadays left heart catheterization alone is adequate for most patients undergoing evaluation of coronary artery disease.

Technique

For right sided pressure monitoring a catheter is inserted into the pulmonary artery. The pulmonary artery catheter (PAC) is frequently referred to as a Swan-Ganz catheter, named after its inventors Jeremy Swan and Willam Ganz in 1970.

A PAC is a 5-7 french catheter which consists of 2-5 lumina with different purposes: a lumen for inflation of the balloon, a proximal and distal lumen for infusion of fluid or extraction of blood, a temperature thermistor and one for RV pacing.

Figure 1. Swan-Ganz catheter.

Ports left to right: thermistor connector, medication portal, proximal injection hub, distal lumen hub, balloon inflation valve with syringe.

Figure 2. Part of the venous and arterial system.

Following local anesthesia, the femoral, jugular, brachial or subclavian vein is punctured, then a guidewire is introduced into the vein by Seldinger technique. Next a sheath is introduced. Femoral access is associated with increased risk of local hemorrhage. When the catheter is left indwelling, the jugular or subclavian vein is preferable, because it allows the patient to sit. The jugular approach is preferred to the subclavian to lessen the risk of pneumothorax and is easiest performed ultrasound guided. The basilica or medial antibrachial vein (the continuation of the basilica in the underarm, see figure 2) can also be used, while contrast via an radial arterial sheath (for cardiac output measurement) will visualize the vein.

After placement of the sheath, the flushed catheter is introduced into the vein and advanced into the inferior vena cava, superior vena cava, right atrium, right ventricle and pulmonary artery (figure 3).

Figure 3. Right heart catheterization from the femoral vein

Top row: the PAC is placed in the right atrium aimed at the lateral wall. Counterclockwise rotation aims the catheter posteriorly and allows advancement into the superior vena cava. Centre row: the catheter is then withdrawn into the right atrium and aimed laterally. Clockwise rotation causes the tip to cross the tricuspid valve. With the tip in a horizontal position, it is positioned below the right ventricular outflow tract. Additional clockwise rotation causes the catheter to point straight up, allowing it to advance into the pulmonary artery and from there into the right pulmonary artery.


Normal and abnormal waveforms

The normal pressure waves in the cardiac chambers during right heart catheterization with normal values shown are shown in figure 4 and 5. After that, we discuss per chamber the pressure curve , normal values and causes of abnormal waveforms.

Figure 4. Normal pressurewaves.


Right atrium

a = atrial systole x= atrial relaxation, decrease of pressure c= closure of the tricuspid valve v= ventricular systole, atrial diastole y= passive filling of right ventricle


Normal RA pressure = 6 mmHg (3 mean) Higher RA pressure in RV infarction, pulmonary hypertension, left to right shunts, tricuspid regurgitation, tamponade, pericarditis constrictiva, restrictive cardiomyopathy.

Abnormal right atrium pressure waves

  1. Elevated a wave: tricuspid stenosis, decreased ventricular compliance due to ventricular failure, pulmonic valve stenosis
  2. Absent a wave: atrial fibrillation
  3. Sawtooth a wave: atrial flutter
  4. Elevated v wave: tricuspid regurgitation (prominent y descent), RV failure
  5. Prominent x descent: tamponade
  6. Kussmaul sign (aspiratory rise of lack of decline in RA pressure): constrictive pericarditis, RV ischemia
Figure 8 Elevated v wave and prominent y descent in tricuspid regurgitation
Figure 9 Prominent y descent (with square root sign) and equalization of RA and RVEDP: tamponade, constrictive pericarditis, restrictive cardiomyopathy

Right ventricle

sys= systole ed= end-diastolic pressure (RVEDP) RF= rapid filling fase (60% of RV filling) SF= slow filling (15% of RV filling) a= atrial contraction (corresponding with a wave of RA curve) (25% of RV filling)

Normal RV pressure = 25 / 4 mmHg When there are no abnormalities in the right heart: CVP = RA pressure = RVEDP. The pressure curve consists of a fast upstroke, a rounded top, directly after the QRS complex. Higher RV pressure in pulmonary hypertension, pulmonic valve stenosis, significant ASD or VSD, pulmonary embolism (in acute pulmonary embolism mostly not above 40-50mmHg).

Abnormal right ventricle pressure waves

  1. Systolic pressure reduced: hypovolemia, cardiogenic shock, tamponade
  2. Elevated end diastolic pressure: cardiomyopathy, RV ischemia and infarction, RV failure, tamponade, pericarditis constrictiva
  3. Decreased end diastolic pressure: tricuspid stenosis
  4. Dip-and-plateau in constrictive pericarditis and restrictive myopathies




References

  1. Wieling W, Ganzeboom KS, and Saul JP. Reflex syncope in children and adolescents. Heart. 2004 Sep;90(9):1094-100. DOI:10.1136/hrt.2003.022996 | PubMed ID:15310717