Role of Transesophageal Echocardiography in ...

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Role of Transesophageal Echocardiography in Surgery for Hemitruncus Arteriosus Satyajeet Misra, MD, DNB, PDCC, TEE (EACVI), FTEE,* Thomas Koshy, DA, MD, PDCC, FTEE, FIACTA,* Pravin Shriram Lovhale, MD,* and Thomas Mathew, MS, MCh†

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n 8-month-old infant weighing 4 kg underwent repair of right hemitruncus arteriosus. Written consent was obtained from the parents for this report. Intraoperative transesophageal echocardiography (TEE) was performed with a Philips IE 33 machine (Philips Ultrasound, Bothell, WA) and a pediatric twodimensional (2D) TEE probe (X8-3t, Philips). The right pulmonary artery (RPA) was seen arising from the proximal ascending aorta in the midesophageal (ME) aortic valve (AV) long-axis view (Figure 1; Supplemental Digital Content 1, Video 1A, http://links.lww.com/ AA/B877). High-velocity flow was seen in the proximal ascending aorta with mild flow acceleration at the level of the AV. The modified ascending aortic (AA) short-axis view showed the main pulmonary artery (MPA) continuing as the left pulmonary artery (LPA) with only a rudimentary stump in place of RPA, without any flows across it (Figure 2; Supplemental Digital Content 1, Video 1B, http://links.lww.com/AA/B877). A patent ductus arteriosus (PDA) with bidirectional shunt (Supplemental Digital Content 2, Video 2A, http://links.lww.com/ AA/B878) and the LPA (Supplemental Digital Content 2, Video 2B, http://links.lww.com/AA/B878) were visualized in the upper esophageal aortic arch long-axis view. The PDA was ligated and divided on initiation of cardiopulmonary bypass. The RPA was seen arising posterolaterally from the aortic root (Figure 3). It was resected from the aorta and reanastomosed to the MPA. Other surgical findings included a subaortic membrane just below the AV, which was excised. After separation from cardiopulmonary bypass, laminar flows were demonstrated in the MPA and RPA with no evidence of stenosis on 2D or color flow Doppler (CFD) (Supplemental Digital Content 3, Video 3, http://links.lww.com/AA/B879). The postsurgical period was uneventful. Hemitruncus arteriosus involves anomalous origin of a branch pulmonary artery (PA) from the aorta, with the other PA arising from MPA; the semilunar valves are normal.1 The incidence is estimated at 0.1% of all congenital

From the *Department of Anesthesiology and †Department of Cardiovascular and Thoracic Surgery, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, India. Accepted for publication April 24, 2017. Funding: None. The authors declare no conflicts of interest. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s website (www.anesthesia-analgesia.org). Reprints will not be available from the authors. Address correspondence to Satyajeet Misra, MD, DNB, PDCC, TEE (EACVI), FTEE, Department of Anesthesiology, All India Institute of Medical Sciences (AIIMS), Bhubaneswar, Odisha, India. Address e-mail to misrasatyajeet@ gmail.com. Copyright © 2017 International Anesthesia Research Society DOI: 10.1213/ANE.0000000000002306

cardiovascular anomalies. The right hemitruncus variant where the RPA arises from the aorta is more common.1 Associated cardiac anomalies are more commonly seen in the left hemitruncus arteriosus (Table).2 Surgical repair is performed in infancy; otherwise, these children develop severe PA hypertension since 1 lung is exposed to systemic arterial pressures and the other lung receives the entire right ventricular cardiac output.1 A combination of 2D and CFD is used to demonstrate the anomalous RPA arising from the proximal ascending aorta in the ME AV long-axis view. Additionally, in the AA short-axis view, the MPA is seen continuing only as the LPA. This confirms the diagnosis of right hemitruncus arteriosus. PDA is present in 69% of patients with right hemitruncus arteriosus. It is usually seen in the upper esophageal short-axis views.3 Interposition of the trachea between the esophagus and the distal AA/proximal aortic arch often results in poor visualization of these structures; saline-filled balloons have been used to minimize ultrasound scattering and improve visualization.3 In infants, however, because of a short trachea, good images of distal AA/proximal aortic arch can be obtained in the upper esophageal views, as compared to adults. It is important to distinguish PDA from LPA with spectral and CFD, as with slight rotation of the probe, both the structures are often seen in this view.4 In contrast to continuous flows in the PDA seen with spectral and CFD, flow in the LPA occurs only in systole and is toward the TEE probe. The MPA is frequently dilated in the presence of PDA due to the left to right shunt; and this may also result in volume overload of the left heart. Antegrade diastolic flows seen in the LPA in this case may have been due to the runoff from the PDA. High-velocity flows were seen in the aortic root and may have been due to the anomalous RPA take off. In the presence of high-velocity flows and elevated gradients, the anomalous PA can be test clamped before commencing cardiopulmonary bypass. Persistence of elevated gradients after clamping the anomalous PA is more suggestive of a fixed systemic left ventricular outflow tract (subvalvular or supravalvular) obstruction. The important goal of post-bypass TEE was to rule out MPA-RPA anastomotic stenosis. 2D is a better modality to delineate anastomotic stenosis, since in severe obstruction, the MPA flow may runoff predominantly into the LPA, thus underestimating the severity of the stenosis by both spectral and CFD. Cutoff values for gradients suggestive of stenosis have not been described. In this case, to delineate the anastomosis, a modified ME long-axis view was used. From the ME AA long-axis view, at the level of RPA, the probe was gently turned leftward in a counterclockwise direction. This maneuver

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Figure 1. Midesophageal aortic valve long-axis view showing (A) right pulmonary artery (RPA) (arrow) originating from the proximal ascending aorta (AO) and (B) increased flow velocities in the AO with color flow Doppler. AV indicates aortic valve; LA, left atrium; RVOT, right ventricular outflow tract.

Figure 2. Modified ascending aortic short-axis view shows the main pulmonary artery (MPA) continuing as the left pulmonary artery (LPA) with only a rudimentary stump in place of right pulmonary artery and no flow across the stump. AO indicates proximal ascending aorta.

aligned the MPA and proximal RPA in the long-axis plane. This view is well aligned with spectral Doppler and allows for interrogation of gradients across the anastomosis. TEE is increasingly being used in surgery for congenital heart disease and is now a standard of care.5 E

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Figure 3. Intraoperative photograph showing the right pulmonary artery (RPA) arising from the posterolateral surface of the proximal ascending aorta.

ANESTHESIA & ANALGESIA


Intraoperative TEE in Hemitruncus

Table. Right Versus Left Hemitruncus Arteriosus Frequency and pathophysiology Associated cardiac anomalies

Echocardiographic features

Clinical significance

Right Hemitruncus Arteriosus •75% of all cases of hemitruncus arteriosus •Right pulmonary artery (RPA) originates from proximal ascending aorta •Mostly isolated finding •Ventricular septal defects may be present

Left Hemitruncus Arteriosus •25% of all cases of hemitruncus arteriosus •Left pulmonary artery (LPA) originates from proximal ascending aorta •Associated anomalies more common and include: ◦Tetralogy of Fallot ◦Interrupted aortic arch (type A) ◦Coarctation of aorta ◦Aortopulmonary window ◦Right aortic arch •RPA arises from proximal ascending aorta and is directed •LPA arises from proximal ascending aorta and is directed toward LA in ME AV LAX view toward RVOT in ME AV LAX view •Bidirectional flows in PDA suggests pulmonary artery •PDA-dependent systemic circulation is seen in interrupted hypertension aortic arch variants Oxygenation takes place in pulmonary lung; therefore, inadvertent endobronchial intubation and ventilation of the systemic lung (supplied by anomalous PA) may cause severe hypoxia

Abbreviations: AV, aortic valve; LA, left atrium; LAX, long axis; ME, midesophageal; PA, pulmonary artery; PDA, patent ductus arteriosus; RVOT, right ventricular outflow tract.

DISCLOSURES Name: Satyajeet Misra, MD, DNB, PDCC, TEE (EACVI), FTEE. Contribution: This author helped design and prepare the manuscript. Name: Thomas Koshy, DA, MD, PDCC, FTEE, FIACTA. Contribution: This author helped in preparing the manuscript. Name: Pravin Shriram Lovhale, MD. Contribution: This author helped in preparing the manuscript. Name: Thomas Mathew, MS, MCh. Contribution: This author helped in preparing the manuscript. This manuscript was handled by: Nikoloas J. Skubas, MD, DSc, FACC, FASE. REFERENCES 1. Prifti E, Bonacchi M, Murzi B, et al. Anomalous origin of the right pulmonary artery from the ascending aorta. J Card Surg. 2004;19:103–112.

2. Diab K, Richardson R, Pophal S, Alboliras E. Left hemitruncus associated with tetralogy of fallot: fetal diagnosis and postnatal echocardiographic and cardiac computed tomographic confirmation. Pediatr Cardiol. 2010;31:534–537. 3. Song H, Liu F, Dian K, Liu J. Echo rounds: intraoperative transesophageal echocardiography-guided patent ductus arteriosus ligation in an asymptomatic nonbacterial endocarditis patient. Anesth Analg. 2010;111:878–880. 4. Tsai SK, Chang CI, Wang MJ, et al. The assessment of the proximal left pulmonary artery by transesophageal echocardiography and computed tomography in neonates and infants: a case series. Anesth Analg. 2001;93:594–597. 5. Ayres NA, Miller-Hance W, Fyfe DA, et al; Pediatric Council of the American Society of the Echocardiography. Indications and guidelines for performance of transesophageal echocardiography in the patient with pediatric acquired or congenital heart disease: report from the task force of the Pediatric Council of the American Society of Echocardiography. J Am Soc Echocardiogr. 2005;18:91–98.

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