A Mobile Threadlike Structure in the Left Atrium: Cor Triatriatum, Artifact, or Thrombus?

A Mobile Threadlike Structure in the Left Atrium: Cor Triatriatum, Artifact, or Thrombus?

A Mobile Threadlike Structure in the Left Atrium: Cor Triatriatum, Artifact, or Thrombus? Sandeep Markan, MD, Nadia Haider, MD, Jutta Novalija, MD, Ph...

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A Mobile Threadlike Structure in the Left Atrium: Cor Triatriatum, Artifact, or Thrombus? Sandeep Markan, MD, Nadia Haider, MD, Jutta Novalija, MD, PhD, Zafar Iqbal, MD, Sweeta D. Gandhi, MD, and Paul S. Pagel, MD, PhD

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77-YEAR-OLD, 121-kg, 172-cm man presented to the authors’ institution for the evaluation of progressive dyspnea on exertion, paroxysmal nocturnal dyspnea, and severe fatigue. The patient had a past medical history of coronary

From the Anesthesia Service, Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, WI. Address reprint requests to Paul S. Pagel, MD, PhD, Clement J. Zablocki Veterans Affairs Medical Center, Anesthesia Service, 5000 W National Avenue, Milwaukee, WI 53295. E-mail: [email protected] © 2009 Elsevier Inc. All rights reserved. 1053-0770/09/2304-0027$36.00/0 doi:10.1053/j.jvca.2008.06.004 Key words: chronic atrial flutter, left atrial thrombus, spontaneous echocardiographic contrast, imaging artifacts and pitfalls, cor triatriatum

artery disease and a previous myocardial infarction that had been medically managed 19 years before admission. The past medical history was remarkable for cardioversion-resistant chronic atrial flutter for which the patient was treated with warfarin. The patient also described a history of hypertension, type II diabetes mellitus, and hypercholesterolemia. A cardiac catheterization revealed occluded right and circumflex coronary arteries, a 70% to 80% stenosis of the mid left anterior descending coronary artery, right and left atrial enlargement, and global left ventricular hypokinesis (ejection fraction of 30%). The patient was transported to the operating room for myocardial revascularization. After anesthetic induction and endotracheal intubation, transesophageal echocardiography revealed the following image (Fig 1 and Video 1 [supplementary videos accompanying this article are available online]). What is the diagnosis?

Fig 1. A midesophageal 4chamber view showing left atrial structure and several regions of spontaneous echocardiographic contrast within the left atrial chamber.

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Journal of Cardiothoracic and Vascular Anesthesia, Vol 23, No 4 (August), 2009: pp 566-568

THIN LEFT ATRIAL THROMBUS

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DIAGNOSIS: THREADLIKE THROMBUS IN THE LEFT ATRIUM ASSOCIATED WITH PRONOUNCED SPONTANEOUS ECHOCARDIOGRAPHIC CONTRAST

A thin, mobile, echogenic structure was observed within the left atrium (Fig 1 and Video 1), which extended into the orifice of left superior pulmonary vein. Large regions of spontaneous echocardiographic contrast were also observed within the chamber, but thrombus was not observed in the left atrial appendage. Color-flow Doppler mapping indicated that intraatrial blood flow across the structure was unimpeded, suggesting that cor triatriatum was not responsible for the observed finding. The structure also was not medially attached to the atrial septum as is typically described in cor triatriatum.1,2 The left atrial structure was also visible in several additional tomographic planes (Fig 2 and Video 2), indicating that the object was most likely not an artifact.3 Cardiopulmonary bypass was instituted after anticoagulation had been achieved with administration of intravenous heparin (400 U/kg). Myocardial protection was provided with mild systemic hypothermia (32°C) and intermittent doses of antegrade and retrograde blood cardioplegia administered at 15- to 20-minute intervals. Saphenous vein grafts were used to bypass severe stenoses in the native posterior-lateral and third obtuse marginal branches of the right and left circumflex coronary arteries, respectively. The left internal mammary artery was used to bypass the left anterior descending coronary artery. The patient converted to normal sinus rhythm upon separation from cardiopulmonary bypass with inotropic support (intravenous milrinone, epinephrine, and norepinephrine). A repeat transesophageal echocardiographic examination revealed that the previously described structure was no longer present within the left atrium and very little residual spontaneous echocardiographic contrast remained (data not shown). Left hemiplegia was observed after emergence from anesthesia, and a cranial computed tomographic scan showed evidence of a new low-density focus in the right precentral gyrus consistent with a recent cerebral infarction. The patient’s postoperative course was complicated by prolonged respiratory insufficiency and acute renal failure requiring dialysis. His left hemiplegia failed to resolve, and he was transferred to the physical medicine and rehabilitation service on the 23rd postoperative day. Cor triatriatum is an unusual congenital cardiac abnormality resulting from the persistence of the embryologic common pulmonary vein, thereby bisecting the left atrium into 2 chambers.4,5 Cor triatriatum is most often described in infants and young children and is rarely encountered in adults unless fenestrations of the intra-atrial membrane allow relatively unobstructed blood flow between the left atrial chambers.6,7 Nevertheless, chronic pressure gradients between the left atrial

Fig 2. A midesophageal long-axis view showing left atrial structure (immediately adjacent to the asterisk) and areas of spontaneous echocardiographic contrast with the left atrial chamber.

chambers may also be observed if blood flow across the membrane is partially obstructed, and, therefore, the clinical presentation of cor triatriatum may mimic mitral stenosis in adults.5,8 Transesophageal echocardiography with or without color-flow Doppler mapping or contrast echocardiography is considered to be the diagnostic imaging technique of choice because of the proximity of the probe to the left atrium.5,7 Notably, the cor triatriatum membrane usually extends across the entire width of the left atrium and attaches to the atrial septum below the origin of the right pulmonary veins.1,2 This was not the case in the current patient in which the observed structure clearly terminated within the body of the left atrial chamber. There were also no apparent pressure gradients within the left atrium observed using color-flow Doppler imaging. Side-lobe artifacts may appear as thin structures within cardiac chambers but may usually be excluded by examination using alternate tomographic imaging planes or by the penetration of these objects through normal anatomic boundaries.3,9 The appearance of the structure observed in the current case was similar in other imaging views, thereby effectively excluding an artifact from the differential diagnosis. The presence of atrial dysfunction resulting from chronic atrial arrhythmias concomitant with large areas of spontaneous echocardiographic contrast is a well-known risk factor for left atrial thrombus development. It appears likely that the conversion of chronic atrial flutter to normal sinus rhythm upon separation from cardiopulmonary bypass may have been the inciting event that triggered embolization of the left atrial thrombus and resulted in the patient’s postoperative cerebrovascular accident.

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