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CARDIOVASCULAR ANESTHESIOLOGY

Right Heart Embolism and Acute Right Atrial Dilation During Total Knee Arthroplasty

From the Department of Anesthesiology and Pain Medicine University of California Davis Medical Center.

Address correspondence and reprint requests to Amrik Singh, MD, 4150 V St., PSSB 1200, Sacramento, CA 95817. Address e-mail to amsingh{at}ucdavis.edu.

A 64-yr-old woman with a history of chronic knee pain and degenerative joint disease presented for a left total knee arthroplasty (TKA) under general anesthesia. Her medical history was significant for asthma and hypertension. Intraoperative transesophageal echocardiography (TEE) was used as part of a research protocol designed to quantify the embolic load associated with this surgical procedure. This protocol to compare embolic load during TKA using two different surgical techniques (standard versus computer-assisted prosthetic implantation) was developed after the death of a patient due to paradoxical embolization through an atrial septal defect (ASD). An initial comprehensive TEE examination revealed normal cardiac chambers and valves, normal ventricular systolic function, and no ASD. The echo probe was then adjusted to obtain and maintain a midesophageal bicaval view. Immediately after the release of the pressure tourniquet (inflation time = 113 min), multiple small emboli were seen passing through the right atrium. These were soon followed by the large horseshoe-shaped embolus shown in Figure 1. Acute right atrial dilation was then observed, as indicated by the leftward bulging of the atrial septum (Fig. 2) (please see full video loop available at www.anesthesia-analgesia.org). Clinically, the patient's oxygen saturation decreased briefly from 100% to 96% despite an inspired oxygen concentration of 100%. Notwithstanding the observed emboli, the patient had a normal postoperative course and was discharged home without complications.

View larger version (38K): [in this window] [in a new window]   Figure 1. Mid-esophageal bicaval view showing a large horseshoe shaped embolus in the right atrium.

View larger version (37K): [in this window] [in a new window]   Figure 2. Mid-esophageal bicaval view showing the inter-atrial septum and its significant bulging after tourniquet release.

Massive intraoperative pulmonary embolism is rare, but catastrophic. A previous Echo Rounds by de Waal et al. (1) presented images of a massive tumor embolus in a patient with renal-cell carcinoma undergoing nephrectomy and tumor thrombectomy. Emergent sternotomy and thrombectomy resulted in a successful outcome. During lower extremity orthopedic procedures including TKA, multiple emboli varying widely in quality, quantity, and clinical consequence are produced resulting in images consistent with those shown in the accompanying video loop (2). These particles are thought to consist of fat, venous thrombi, and bone fragments.

The total embolic load has been characterized qualitatively and quantitatively in these patients. Parmet et al. (2) classified the emboli as absent, small, or large (>0.5 cm) and documented that avoiding the use of a pressure tourniquet decreased the number of emboli. Hirota et al. (3) used computer-assisted image analysis software to quantify the extent of right atrial opacification and demonstrated an association between tourniquet time and total embolic load.

The clinical significance of the observed emboli in these patients is difficult to determine. Sulek et al. (4) studied 22 patients undergoing TKA with simultaneous TEE and transcranial Doppler and observed cerebral emboli in nearly 60% of the patients. Eight patients demonstrated echogenic material in the left atrium (two through a patent foramen ovale and six from the pulmonary veins). These observed hemodynamic or neurologic sequale are not commonly critical; however, as the population of patients undergoing TKA continues to expand to include patients with more severe coexisting disease, significant clinical consequences could be anticipated. Although TEE has been used with varying degrees of success to visualize pulmonary embolism directly, the secondary signs may provide a means to assess the severity of the observed embolic load (5,6). In a series of 46 patients undergoing emergency pulmonary embolectomy, Rosenberger et al. (5) reported that visualization of a thrombus in the pulmonary vasculature was possible in only 26% of the patients but that secondary signs of acute right heart outflow obstruction, including right ventricular (RV) dysfunction (96%), tricuspid valvular regurgitation (50%), and leftward bulging of the atrial septum (98%), were more consistently demonstrated. In a similar study of 63 patients with acute pulmonary thromboembolism, Chung et al. (6) found that RV hypokinesis, RV end-systolic area, and RV ejection area, as well as the ratio of right to left ventricular end-diastolic area and right to left atrial end-systolic area, all strongly correlated with the extent of pulmonary artery obstruction. However, the incidence and severity of the hemodynamic consequences of the emboli observed during routine TKA are such that its routine use for intraoperative monitoring and screening for ASDs in these patients is not indicated. Moreover, it is not possible to perform TEE in patients undergoing this procedure under regional anesthesia. The potential benefits, including less blood loss and better surgical field, are probable reasons for the widespread use of pressure tourniquets.

In the present case, continuous recording of the right atrium was mandated by the study protocol. No other views were obtained to observe the passage of thrombus through the pulmonary artery. Other secondary TEE signs could not be evaluated specifically, but the transient bulging of the atrial septum is quite easily seen. These dramatic TEE images serve as a reminder of the potential for rare, but clinically severe, thromboembolism during knee arthroplastic surgery.

Footnotes

This article has supplementary material on the Web site: www.anesthesia-analgesia.org.

Accepted for publication June 28, 2007.

REFERENCES

1. de Waal EEC, Bruins P, Lahpor JR, Steijling JJF, de Kort LMO, Boon TA. Chasing the tumor thrombus. Anesth Analg 2005;101:332[Free Full Text]
2. Parmet JL, Horrow JC, Berman AT, Miller F, Pharo G, Collins L. The incidence of large venous emboli during total knee arthroplasty without pneumatic tourniquet use. Anesth Analg 1998;87:739–44
3. Hirota K, Hashimoto H, Kabara S, Tsubo T, Sato Y, Ishihara H, Matsuki A. The relationship between pneumatic tourniquet time and the amount of pulmonary emboli in patients undergoing knee arthroscopic surgeries. Anesth Analg 2001;93:776–80[Abstract/Free Full Text]
4. Sulek CA, Davies LK, Enneking FK, Gearen PA, Lobato EB. Cerebral microembolism diagnosed by transcranial doppler during total knee arthroplasty: correlation with transesophageal echocardiography. Anesthesiology 1999;91:672–6[Web of Science][Medline]
5. Rosenberger P, Shernan S, Body SC, Eltzschig HK. Utility of intraoperative transesophageal echocardiography for diagnosis of pulmonary embolism. Anesth Analg 2004;99:12–6[Abstract/Free Full Text]
6. Chung T, Emmett L, Khoury V, Lau G, Elsik M, Foo F, Allman K, Kritharides L. atrial and ventricular correlates of the extent of pulmonary embolism in the elderly. J Am Soc Echocardiogr 2006;19:347–53[Web of Science][Medline]

This Article Full Text (PDF) Echo Loop Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Singh, A. Articles by Fleming, N. Search for Related Content PubMed PubMed Citation Articles by Singh, A. Articles by Fleming, N. Related Collections Cardiovascular Heart Complications Echo Rounds Patient Safety Video Clip