A pulmonary artery catheter allows direct measurements of pressures in the right heart and the pulmonary artery, sampling of mixed venous blood, estimation of left-sided pressures and cardiac output (1). Placement of a pulmonary artery catheter depends on recognition of the changes in the pressure waveforms as the catheter passes through the right heart into the pulmonary artery. In this report, we present a case in which placement of a pulmonary artery catheter based on changes in pressure waveforms led to its incorrect placement in the coronary sinus, which was diagnosed by transesophageal echocardiography (TEE).
An 80-yr-old female patient with a history of chronic renal insufficiency and peripheral vascular disease was scheduled for infrainguinal vascular bypass surgery. The patient had been enrolled in a research study examining the role of TEE in vascular surgery and her intraoperative monitoring was to include a pulmonary artery catheter as well as TEE. After an uneventful induction of general anesthesia, central venous access (Percutaneous Sheath Introducer Set S3508BF09; Edwards Life Sciences, Irvine, CA) was obtained through the right internal jugular vein. The pulmonary artery catheter (VIP thermodilution catheter 834HF75; Edwards Life Sciences) was advanced with the balloon inflated, and an apparent “wedge” tracing was obtained on the pressure monitor at 50 cm length. The balloon was then deflated and a pulsatile waveform was obtained.
During the subsequent TEE examination, the pulmonary artery catheter was noted to be in the coronary sinus, and not in the pulmonary artery (Figures 1 and 2). The pulmonary artery catheter was withdrawn and advanced under TEE guidance. TEE visualization showed the catheter advanced through the superior vena cava and right atrium and into the right ventricle with appropriate corresponding pressure waveforms. However, as visualized by TEE, further advancement of the catheter caused it to “flip” out of the right ventricle, back into the right atrium and into the coronary sinus. The pressure waveform at this point appeared to be very similar to an expected pulmonary artery pressure tracing; however, it actually represented a coronary sinus occlusion pressure. Injection of agitated saline into an arm vein failed to demonstrate the appearance of air bubbles in the coronary sinus, indicating the absence of a persistent left superior vena cava (PLSVC). There was mild to moderate tricuspid regurgitation and the central venous pressure was 22 mm Hg. The surgical team was informed, the pulmonary artery catheter removed, and a double-lumen central venous catheter was placed. The rest of the surgery proceeded uneventfully (Fig. 2).
This is the first report of incorrect placement of a pulmonary artery catheter in the coronary sinus, in the absence of a congenital cardiac anomaly such as PLSVC, diagnosed by TEE. The incorrect placement occurred even though the changes in the pressure waveforms appeared appropriate and the depth of insertion seemed adequate. If unrecognized, further complications such as trauma to the coronary sinus, misinformation regarding the pulmonary artery pressures and cardiac outputs, and under-estimation of mixed venous saturation might have ensued.
The coronary sinus is a 3-cm long and 1-cm wide structure that travels in the left atrioventricular groove and empties into the right atrium just superior to the tricuspid valve. It is a continuation of great cardiac veins and drains 95% of coronary venous blood. Because of extensive arteriovenous anastomoses in the coronary circulation, a catheter wedged in the coronary sinus would give an arterialized pressure tracing and reflect attenuated systemic pressures (2). This fact is often used when a retrograde cardioplegia catheter is intentionally placed into the coronary sinus and its placement confirmed by a pulsatile pressure tracing.
The coronary sinus can be dilated in conditions where the central venous pressures are high, there is retrograde flow from posterior-directed tricuspid regurgitation jet, or in congenital abnormalities such as an unroofed coronary sinus or a PLSVC (3). Partial anomalous pulmonary venous return is often associated with PLSVC (4) and may also predispose to incorrect placement of a pulmonary artery catheter, although this has not been reported. A dilated coronary sinus may make it easier for a pulmonary artery catheter to be placed. Whereas pulmonary artery catheter placement in the coronary sinus in the presence of a PLSVC has been reported (3,5,6), our report is the first to note the occurrence in the absence of PLSVC and to diagnose it with TEE. In our case, the predisposing factor might have been tricuspid regurgitation and increased central venous pressures.
The misplacement of a catheter in the coronary sinus can be diagnosed with fluoroscopy, determination of oxygen content and saturation of blood aspirated through the distal port, and systemic pressure waveform tracings (7). Depending on the degree of occlusion of the coronary sinus, the pressure waveform may resemble right atrial, right ventricular, or left ventricular pressure waves (7). Cannulation of the coronary sinus is associated with minor myocardial damage in approximately >10% of cases and may include major complications, such as coronary sinus rupture, tamponade, and right ventricular rupture (8). The chances of complications may increase with inadvertent or prolonged cannulation of the coronary sinus (7). Other than determination of oxygen content and saturation of the aspirated blood, all the described methods are time-consuming and cumbersome. The pressure waveforms depend upon the degree of occlusion and may not be discerning as to the position of the catheter. Oxygen content and saturation determination does not provide a definite diagnosis of coronary sinus placement but, rather, provides confirmatory evidence after the diagnosis of catheter placement in the coronary sinus is made by some other means. On the other hand, TEE is simple to use in the hands of an experienced echocardiographer and can provide a rapid confirmation of the position of the pulmonary artery catheter either in the pulmonary artery or the coronary sinus. The possibility of a misplaced pulmonary artery catheter should be entertained whenever the data obtained with the catheter do not correlate with the clinical picture or when the placement involves multiple attempts. Use of TEE for verification of correct placement and positioning of intracardiac devices is a category II indication of TEE (9). TEE allows a rapid recognition of inadvertent cannulation of the coronary sinus and can help in accurate positioning of the pulmonary artery catheter.
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