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Cardiovascular Anesthesiology: Original Clinical Research Report

The Use of Standard Gastrointestinal Endoscopic Ultrasound to Assess Cardiac Anatomy

Sentissi, Kinza MD*; Sawhney, Mandeep S. MD, MS; Pleskow, Douglas MD; Sepe, Paul MD; Mella, Jose M. MD§; Kwittken, Benjamin MD, BS; Ketwaroo, Gyanprakash MD, MSc; Subramaniam, Balachundhar MBBS, MD, MPH

Author Information
doi: 10.1213/ANE.0000000000001380

Abstract

Endoscopic ultrasound (EUS) has gained popularity in academic medical centers as well as community hospitals. It is now routinely performed for staging of luminal malignancies as well as assessment of pancreaticobiliary and mediastinal disease.1–6 During the standard EUS examination, it is possible to visualize the aorta and several cardiac structures7–9; however, this has not been systematically studied or reported. The ability to perform a cardiac examination comparable to that of a transesophageal echocardiogram (TEE) using EUS equipment could be potentially beneficial. For example, in the event of hemodynamic instability in the endoscopy suite, resulting from hypovolemia, depressed ventricular function, aortic dissection, pericardial effusions, or critical aortic stenosis, EUS cardiac examination could provide vital clinical information to facilitate immediate resuscitation. The purpose of our study was to prospectively investigate the feasibility of detecting cardiac anatomic structures and measures of cardiac function using EUS technology.

METHODS

With institutional review board approval, patients who were scheduled to undergo EUS for standard clinical indications were invited to participate in the study. Given that this was a preliminary observational study, we chose a convenience sample of 20 patients for the study. Written informed consent was obtained from all subjects or their legal surrogate. EUS was performed using a standard technique by 1 of 2 experienced gastroenterologists. After completion of the EUS examination, assessment of cardiac structures was performed with the assistance of a TEE-certified cardiac anesthesiologist.

All EUS procedures were performed using the Olympus linear echoendoscope GF-UCT180, Olympus radial echoendoscope GF-UE160-AL5, and Aloka ProSound Alpha10 ultrasound processor (Olympus America Inc, Center Valley, PA). It is important to note that although the TEE probe has the ability to scan in a plane ranging from 0° to 180°,10,11 the ultrasound transducer in the linear EUS endoscope is fixed and only scans from 120° to 180°, depending on the manufacturer. The imaging plane of the EUS echoendoscope can only be changed by flexing the tip of the endoscope; retroflexion and lateral flexion are not possible. In addition, Doppler-dependent measures were not attempted given that the Doppler functionality of the EUS linear endoscope is programmed for low flow rates (5–10 Hz)12; therefore, the current technology is not able to evaluate higher flow rates as would be required to assess cardiac variables. Notably, the frame rate for the images was approximately 18 Hz, which is less than most modern 2-dimensional TEE phase array transducers, which typically are obtained in a frame rate of 30 to 60 Hz.

After the EUS gastrointestinal examination was complete, a cardiac assessment was performed. The endoscopist was verbally guided through the standard TEE positioning and manipulations by a cardiac anesthesiologist, and each examination took approximately 10 minutes. The images obtained were compared with the standard 20 views as per the American Society of Echocardiography/Society of Cardiovascular Anesthesiologists (ASE/SCA) guidelines for TEE as was the standard at the time of the study.10,11 Each view was graded as either “visualized” or “not visualized.” If a view was visualized, this meant that it was comparable with the same view obtained by TEE standards; however, it is important to note that TEE examinations were not done in these patients for formal comparison. In addition, right ventricular (RV) and left ventricular (LV) systolic functions and regional wall motion were assessed qualitatively, that is, visualized or not visualized; however, no quantitative measurements were taken.

At the time of assessment of the standard views and ventricular function, each valve was also evaluated and graded as visualized or not visualized. The Doppler-dependent measures of cardiac function were not possible. All images were reviewed and graded at the time they were obtained by a cardiac anesthesiologist and were not reviewed by a second reviewer. All EUS examinations were performed under monitored anesthesia care by another dedicated anesthesiologist, who was not involved in the study. It was predetermined that if any cardiac abnormalities were uncovered, these would be discussed with the patient and appropriate follow-up with cardiology and a primary treating physician would be arranged. After the EUS evaluation, patients recovered and were discharged per standard clinical practice. This was a qualitative study and, therefore, no formal comparison was planned or attempted with any statistical test.

RESULTS

Of the 20 patients included in the study, 18 underwent examination with the linear echoendoscope, and 2 underwent examination with the radial echoendoscope. Views with the radial scope were extremely limited given the cross-sectional nature of this scope; therefore, the remainder of this Results section pertains to the data collected using the linear endoscope. The mean age of study patients was 66 ± 17 years, 70% were female, and mean body surface area was 1.70 ± 0.2 m2. One gastroenterologist (operator A) performed 65% of the examinations. The most common indication for EUS investigation with the linear echoendoscope was assessment of pancreatic etiology (72%). Of the patients included, 1 patient had a known history of tricuspid regurgitation and another had a history of aortic stenosis and aortic valve (AV) replacement. The remaining patients had no known history of valvular disease. None of the patients in the study had a known history of congestive heart failure.

After a standard EUS examination, an attempt was made to obtain the 20 TEE views as per the ASE/SCA guidelines as was the standard at the time this study was conducted, before the 2013 recommendations.10,11 The following views were consistently visualized and comparable with those obtained by TEE in quality: midesophageal (ME) bicaval view (Figure 1; Supplemental Digital Content, Supplemental Video 1, http://links.lww.com/AA/B429) ME AV long-axis view (LAX) (Figure 2), ME AV short-axis view (Figure 3), ME 2-chamber view (Figure 4), ME RV inflow-outflow tract view, ME mitral commissural view, transgastric LAX view, and transgastric RV inflow tract view. The other standard views were not visualized.

Figure 1.
Figure 1.:
Midesophageal bicaval view: This is a midesophageal view where the eustachian valve, intra-atrial septum, left atrium (LA), right atrium (RA), superior (SVC), and inferior vena cava can be seen. This is an excellent view to view to look for patent foramen ovale (PFO), atrial septal defects (ASD), or to perform a bubble study.
Figure 2.
Figure 2.:
Midesophageal aortic valve (AV) long-axis view: This is a midesophageal view where the left ventricle (LV), mitral valve, left atrium (LA), AV, aorta, and the right ventricular (RV) outflow tract can be seen.
Figure 3.
Figure 3.:
Midesophageal aortic valve (AV) short-axis view: This is a midesophageal view commonly found perpendicular to the long-axis view. In this view the AV, tricuspid valve, right atrium, intra-atrial septum, right ventricular outflow tract, pulmonic artery (PA), and left atrium (LA) can be seen.
Figure 4.
Figure 4.:
Midesophageal 2-chamber view: This is a midesophageal view where the left atrium (LA), mitral valve, left ventricle (LV), and sometimes the left atrial appendage and the coronary sinus can be seen.

LV systolic function could be assessed in 89% of patients. While examining LV systolic variables, the linear echoendoscope reliably assessed anterior, anteroseptal, inferior, and posterior wall motions as well. The RV free wall was visualized in 67% of patients. RV systolic function was assessed in all patients. However, given that no comparison was made to TEE in these patients, we cannot comment on the accuracy of this assessment of cardiac function, and this also applies to assessment of regional wall motion. Further studies would need to be performed comparing the assessment of LV and RV functions as well as regional wall motion in EUS compared with the standard TEE. Doppler-dependent assessments of LV systolic function could not be assessed.

The AV was consistently visualized with the linear echoendoscope in 100% of patients. Two leaflets were visualized in 100% of patients via the ME AV LAX view. The 3-cusp view via the ME AV short-axis was seen in 22% of patients. Doppler-dependent measures of valvular function such as velocities and regurgitant flows were unable to be assessed in this study. In the patient who had undergone previous AV replacement, the prosthetic AV was readily visualized.

Both leaflets of the mitral valve were consistently seen with the linear echoendoscope in 100% of patients. The tricuspid valve was visualized in 33% of patients, and in these cases, only 2 leaflets were observed (Figure 5). The pulmonic valve was visualized in 11% of patients.

Figure 5.
Figure 5.:
View of the tricuspid valve. LA indicates left atrium; RA, right atrium; RV, right ventricle.
Figure 6.
Figure 6.:
Midesophageal ascending aorta long-axis view. AA indicates ascending aorta.

The ascending (Figure 6) and descending aorta were visualized in 100% of patients. The pericardium was seen in 100% of patients, and no effusions were noted. The left atrial appendage and interatrial septum were visualized in 100% of patients.

DISCUSSION

In this prospective observational study, we found that 8 of 20 ASE/SCA TEE guideline views were readily obtained during EUS examination with the linear echoendoscope. LV systolic function and AV and mitral valve anatomy could be evaluated in most patients but definitive quantitative measures regarding systolic function or valvular function could not be extrapolated given the lack of reference TEE and Doppler capability. Other important structures such as the ascending and descending aorta, pericardium, left atrial appendage, and interatrial septum were identified in all patients. Right-sided cardiac structures such as tricuspid valve and pulmonary valve anatomy could only be visualized in a minority of patients. Doppler-dependent functions could not be assessed in any patient.

Some limitations of our study deserve further discussion. First, gastroenterologists who performed this study were not fluent with TEE, and all examinations were performed under the direction of a TEE-certified cardiac anesthesiologist. However, the purpose of our study was to determine the feasibility of cardiac assessment using EUS technology and not the performance of the gastroenterologist with regard to cardiac assessment. Second, the key difference between the EUS and the TEE endoscopes is their field of imaging. The narrow imaging plane of the EUS endoscope contributes to the limited view of the right side of the heart. Currently available EUS echoendoscopes are analogous to the monoplane TEE endoscopes used in the past, which had similar limitations.

Our results suggest that the presently available linear EUS echoendoscope is unable to capture the full breadth of cardiac imaging and functional assessment seen with TEE; however, it is able to give valuable information concerning the left side of the heart. The ability of EUS technology to evaluate the mentioned cardiac variables could be invaluable in a hemodynamically unstable patient with a EUS linear endoscope already in place. For an approximate estimate of LV function, volume status, aortic, and mitral valvular pathology as well as pericardial effusions and aortic pathology, EUS technology could help direct immediate clinical care. However, it is important to note that definitive diagnostic tests such as a formal echocardigraphic assessment by a qualified operator are still mandated if deemed necessary to evaluate a hemodynamically unstable patient in the endoscopy suite.

DISCLOSURES

Name: Kinza Sentissi, MD.

Contribution: This author helped conduct the study, analyze the data, and write the manuscript.

Name: Mandeep S. Sawhney, MD, MS.

Contribution: This author helped conduct the study, analyze the data, write the manuscript, and perform gastrointestinal endoscopy.

Name: Douglas Pleskow, MD.

Contribution: This author helped conduct the study, write the manuscript, and perform gastrointestinal endoscopy.

Name: Paul Sepe, MD.

Contribution: This author helped conduct the study and write the manuscript.

Name: Jose M. Mella, MD.

Contribution: This author helped conduct the study and write the manuscript.

Name: Benjamin Kwittken, MD, BS.

Contribution: This author helped conduct the study and write the manuscript.

Name: Gyanprakash Ketwaroo, MD, MSc.

Contribution: This author helped conduct the study and write the manuscript.

Name: Balachundhar Subramaniam, MBBS, MD, MPH.

Contribution: This author helped design the study, conduct the study, analyze the data, and write the manuscript.

This manuscript was handled by: Martin J. London, MD.

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