Volume 26, Issue 1 , Pages 175-177, February 2012
A Large Mass on a Newly Implanted Pulmonary Artery Catheter: Thrombus, Vegetation, or an Anatomic Explanation?
Article Outline
- Diagnosis: Large Right Ventricular Anterior Papillary Muscle Adjacent to the PAC Mimicking Thrombus or Vegetation
- Supplementary data
- References
- Copyright
Key words: right ventricle , papillary muscle , tricuspid valve , pulmonary artery catheter , imaging pitfalls
A 62-YEAR-OLD, 92-kg, 168-cm woman was admitted to the authors' medical center for elective coronary artery bypass graft surgery. The patient described a 3-week history of progressive exertional chest pain, dyspnea, and dizziness relieved with rest. She recently had been evaluated at another hospital for similar symptoms, and an acute myocardial infarction was excluded based on analysis of serial cardiac enzymes. The patient denied a past medical history of fever, chills, nausea, vomiting, diaphoresis, orthopnea, and leg swelling. No murmurs were heard during cardiac auscultation. The remainder of the physical examination was otherwise noncontributory. An electrocardiogram showed normal sinus rhythm without ischemic changes. The laboratory analysis, including a coagulation panel, was unremarkable. The cardiac catheterization revealed a 90% stenosis of the left anterior descending (LAD) coronary artery distal to the first diagonal branch and a series of discrete high-grade stenoses in the left circumflex coronary artery (LCCX) proximal and distal to a large second marginal branch. The left ventricular ejection fraction was estimated at 65%. The patient was transported to the operating room for coronary artery bypass graft surgery. A pulmonary artery catheter (PAC) was inserted through the right internal jugular vein using local anesthesia, conscious sedation (intravenous midazolam and fentanyl), and ultrasound guidance. A transesophageal echocardiographic (TEE) probe was placed immediately after anesthetic induction, endotracheal intubation, and gastric decompression. TEE revealed an apparent “mass” associated with the PAC (Fig 1 and Video 1 [supplementary videos are available online]). What is the diagnosis?
Fig 1.
Midesophageal right ventricular inflow-outflow image showing a large “mass” associated with the pulmonary artery catheter.
Diagnosis: Large Right Ventricular Anterior Papillary Muscle Adjacent to the PAC Mimicking Thrombus or Vegetation
The midesophageal right ventricular (RV) inflow-outflow TEE imaging plane showed the presence of a large “mass” associated with the PAC throughout the cardiac cycle (Fig 1 and Video 1). The catheter recently had been inserted, and a thrombus appeared to be highly unlikely because of the presence of normal sinus rhythm and the absence of a hypercoagulable state. Similarly, the diagnosis of a catheter-associated vegetation was excluded based on the absence of signs and symptoms of infection and the short duration between catheter insertion and the subsequent TEE examination (<10 minutes). A midesophageal 4-chamber view revealed a large anterior papillary muscle inserted into the RV apex (Fig 2 and Video 2). A moderator band was absent. The PAC was observed to be in close proximity to this papillary muscle when Video 2 was examined in slow motion. The LAD and LCCX stenoses were bypassed using the left internal mammary artery and a saphenous vein graft, respectively. The patient separated from cardiopulmonary bypass without inotropic support and was transferred to the surgical intensive care unit in stable condition. The remainder of her hospital course was uneventful. She was discharged on the 4th postoperative day.
Fig 2.
A midesophageal 4-chamber image showing a large anterior papillary muscle inserting into the right ventricular apex.
The tricuspid valve (TV) leaflets, papillary muscles, and chordae tendineae are remarkably heterogenous structures from an anatomic perspective.1, 2, 3 The TV usually is composed of a large anterior leaflet, a posterior leaflet with several scallops, and a small septal leaflet,4 but many variations frequently are encountered. For example, Wafae et al5 showed that the TV was not consistently tricuspid, but contained 2, 4, 5, or 6 cusps in 72% of 50 dissected human hearts. Similarly, the tricuspid papillary muscles and their chordae are structurally quite diverse. Nigri et al2 showed that RV anterior and posterior papillary muscles were present in all 72 human hearts examined in their study, but these muscles frequently contained 2 or more heads and as many as 11 chordae tendineae with highly variable distribution to the valve leaflets. The septal papillary muscle was absent in more than 20% of hearts,2 and considerable debate continues among anatomists, cardiologists, and cardiac surgeons about septal papillary muscle embryology, morphology, and nomenclature.6, 7, 8, 9, 10 The RV also contains a wide variety of fibromuscular or conduction tissue false tendons that do not attach to the valve leaflets per se, but instead traverse the chamber between the RV free wall, papillary muscles, and conduction system.11 The inherent structural diversity of the TV apparatus and alterations in its geometry imposed by pathologic processes are important determinants of tricuspid regurgitation12, 13 and also may contribute to the development of recurrent or residual tricuspid regurgitation after annuloplasty.3, 14 The anterior papillary muscle observed in the current patient was a relatively large variant and inserted directly into trabeculations within the RV apex. This observation is consistent with recent x-ray multidetector computed tomography data indicating that papillary muscles do not attach directly to the solid heart wall, but rather originate from the trabeculae carnae lining the right and left ventricular walls.15 The anterior papillary muscle usually arises from the moderator band near the RV free wall,1 but the moderator band was absent in the current patient. A moderator band was identified in the vast majority (92%) of human hearts examined in an anatomic study but was not present in the remainder.16 The large size and apical insertion of the anterior papillary muscle in the current case allowed it to be seen well in the oblique cross section in the TEE RV inflow-outflow tract imaging plane, thereby mimicking a mass associated with the PAC.
Supplementary data
Video 1. A midesophageal right ventricular inflow-outflow clip showing a large “mass” associated with the pulmonary artery catheter throughout the cardiac cycle.
Video 2. A midesophageal 4-chamber clip showing a large anterior papillary muscle inserting into the right ventricular apex; the pulmonary artery catheter is observed in close proximity to this papillary muscle when the clip is viewed in slow motion.
References
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- Anatomical study of the human tricuspid valve . Surg Radiol Anat . 1990;12:37–41
- . Normal variations in tricuspid valve attachments to the membraneous ventricular septum: A clue to the etiology of the left ventricle-to-right atrial communication . Am Heart J . 1975;89:186–188
- The medial papillary muscle complex and its related septomarginal trabeculation (A normal anatomical study on human hearts) . J Anat . 1989;163:231–242
- . Variations in the papillary muscles of the normal mitral valve and their surgical relevance . J Cardiac Surg . 1995;10:597–607
- The morphology and distribution of the tendinous chords and their relation to the papillary muscles in the tricuspid valve of the human heart . Folia Morphol (Warsz) . 2007;66:314–322
- Remarks on the morphology of the papillary muscles of the right ventricle . Folia Morphol (Warsz) . 2005;64:176–182
- Right ventricular false tendons, a cadaveric approach . Surg Radiol Anat . 2008;30:317–322
- Geometric and hemodynamic determinants of functional tricuspid regurgitation: A real-time three-dimensional echocardiography study . Int J Cardiol . 2008;124:160–165
- Spinner EM, Sundareswaran K, Prasad Dasi L, et al: Altered right ventricular papillary muscle position and orientation in patients with a dilated left ventricle. J Thorac Cardiovasc Surg (in press)
- Determinants of recurrent or residual functional tricuspid regurgitation after tricuspid annuloplasty . Circulation . 2006;114(suppl 1):I582–I587
- . Papillary muscles do not attach directly to the solid heart wall . Circulation . 2004;109:3145–3148
- Anatomical observations of the moderator band . Clin Anat . 2010;23:443–450
PII: S1053-0770(10)00323-X
doi:10.1053/j.jvca.2010.07.025
© 2012 Elsevier Inc. All rights reserved.
Volume 26, Issue 1 , Pages 175-177, February 2012
