Introduction to Intraoperative Echocardiography

1 Introduction to Intraoperative Echocardiography



Carol Kraft, Donald C. Oxorn



Background




• The intraoperative setting can be daunting, even to experienced practitioners who do not spend the bulk of their clinical time in the operating room (OR).

• Factors that limit optimal image acquisition include bright lights and lots of noise.

• Time may be limited because several different physicians and nurses have responsibilities in surgical preparation and the surgical procedure.

• This chapter describes
• The fundamentals of echocardiographic imaging in the OR.

• Some basic physics and instrumentation.

• Ultrasound artifacts that are particularly important for the intraoperative echocardiographer.

• Subsequent chapters delve into the details of image acquisition in specific clinical settings.


Transesophageal Echocardiography Procedural Issues



• After the induction of anesthesia, make sure the patient is being cared for by someone who is not distracted by the ultrasound examination.

• Start obtaining data as early as possible. This maximizes the available time for imaging before the surgical procedure starts.

• If feasible, request that the lighting be dimmed, or at a minimum, direct any overhead surgical lighting away from the echocardiography machine.

• Address any unresolved diagnostic imaging questions first.
• For example, if the patient is known to have critical aortic stenosis and is scheduled for aortic valve replacement, it is unlikely that the intraoperative echocardiogram will alter that plan.

• Conversely, if the same patient has concurrent mitral regurgitation that has been difficult to quantify, and in which there is confusion regarding the underlying mechanism, this is something that needs to be clarified before the surgery begins.

• Know the preoperative data (transesophageal echocardiography [TTE], heart catheterization, computed tomography [CT], magnetic resonance imaging [MRI]), and review the images, if possible, to assess data quality.

• Speak to the surgeon and find out what information is needed from the intraoperative examination. If, as often occurs, you discover previously undiagnosed pathology, do not hesitate to share this information with the surgeon.

• Once the surgery begins, electrocautery will inevitably be used, which interferes with the two-dimensional (2D) and Doppler signals. Try to get crucial information before this situation exists.

• Electronic interference with the electrocardiogram (ECG) prevents appropriate triggering of cine loop recording from the QRS complex. Instead, set the echocardiography instrument to store data for a set length of time instead of a set number of beats.

• Record blood pressure and other parameters of loading conditions during echo acquisition so that pre- and postprocedure data can be interpreted in the context of the loading conditions.


Key Points



• Most general anesthetic agents diminish vascular tone and depress myocardial contractility.

• Positive pressure ventilation has numerous hemodynamic effects that have the potential to alter echocardiographic findings.

• Cardiopulmonary bypass, especially when prolonged, has profound effects on vascular tone and systolic and diastolic function.


Indications, Contraindications, and Complications of Intraoperative Transesophageal Echocardiography



• Shanewise’s classic review1 (Table 1-1; see also Figure 1-1) provides a common template on which to base an intraoperative TEE examination.

• Less traditional or “off-axis” views are often needed to adequately document abnormalities.

• The indications for intraoperative TEE have evolved, in keeping with a dramatic increase in surgical complexity; patients presenting for coronary revascularization are rarely without significant comorbidities.

• A number of recent documents relating to the local practice of, and training in, intraoperative echocardiography are referenced at the end of this chapter.4–7

TABLE 1-1 RECOMMENDED TRANSESOPHAGEAL ECHOCARDIOGRAPHY CROSS SECTIONS

image

image

Figure 1-1 A-T, Twenty cross-sectional views composing the recommended comprehensive TEE examination. Approximate multiplane angle is indicated by the icon adjacent to each view. asc, ascending; AV, aortic valve; desc, descending; LAX, long axis; ME, midesophageal; RV, right ventricle; SAX, short axis; TG, transgastric; UE, upper esophageal.


A-T, From Shanewise JS, Cheung AT, Aronson S, et al. ASE/SCA guidelines for performing a comprehensive intraoperative multiplane transesophageal echocardiography examination: Recommendations of the American Society of Echocardiography Council for Intraoperative Echocardiography and the Society of Cardiovascular Anesthesiologists Task Force for Certification in Perioperative Transesophageal Echocardiography. Anesth Analg. 1999;88:870-874.



From European Association of Echocardiography. Recommendations for transoesophageal echocardiography: update 2010. Eur J Echocardiogr. 2010;11:557-576.


Key Points


Provided that there is appropriate technology available and that those charged with undertaking TEE have the knowledge and skills appropriate to the task, it is therefore recommended that:


• TEE should be used in adult patients undergoing cardiac surgery or surgery to the thoracic aorta under general anesthesia, in particular, in valvular repair procedures.

• TEE may be used in patients undergoing specific types of major surgery where its value has been repeatedly documented. These include
• Neurosurgery at risk from venous thromboembolism.

• Liver transplantation, lung transplantation, and major vascular surgery, including vascular trauma.

• Patients undergoing major noncardiac surgery in whom severe or life-threatening hemodynamic disturbance is either present or threatened.

• Patients having major noncardiac surgery who are at a high cardiac risk, including severe cardiac valve disease, severe coronary heart disease, or heart failure.

• TEE may be used in the critical care patient in whom severe or life-threatening hemodynamic disturbance is present and unresponsive to treatment or in patients in whom new or ongoing cardiac disease is suspected and who are not adequately assessed by transthoracic imaging or other diagnostic tests.

• The contraindications and complications of intraoperative TEE are described in Tables 1-2 and 1-3 and Figures 1-2 to 1-5. In general, these are the same as with TEE performed outside the OR with several caveats:
• In the OR, the patient is under general anesthesia when the probe is introduced. Although these conditions facilitate probe insertion, patients are unable to indicate when excessive pressure is inapproriately applied.

• In the OR, the probe may be left in the patient for extended periods of time.

TABLE 1-2 SUGGESTED CONTRAINDICATIONS TO TRANSESOPHAGEAL ECHOCARDIOGRAPHY

































Absolute Contraindications Relative Contraindications
Perforated viscous Atlantoaxial joint disease with restricted mobility
Esophageal pathology (stricture, trauma, tumor, scleroderma, Mallory-Weiss tear, diverticulum)* Severe cervical arthritis with restricted mobility
Active upper GI bleeding Prior radiation to the chest
Recent upper GI surgery Symptomatic hiatal hernia
Esophagectomy, esophagogastrectomy History of GI surgery
Recent upper GI bleed
Esophagitis, peptic ulcer disease
Thoracoabdominal aneurysm
Barrett’s esophagus
History of dysphagia
Coagulopathy, thrombocytopenia

GI, gastrointestinal.


* TEE may be used for patients with oral, esophageal, or gastric disease if the expected benefit outweighs the potential risk, provided the appropriate precautions are applied. These precautions may include considering other imaging modalities (e.g., epicardial echocardiography), obtaining a gastroenterology consultation, limiting the examination, avoiding unnecessary probe manipulation, and using the most experienced operator.


From Hilberath JN, Oakes DA, Shernan SK, et al. Safety of transesophageal echocardiography. J Am Soc Echocardiogr. 2010;23:1115-1127.


TABLE 1-3 COMPLICATION RATE

































Complication Incidence
Dental injuries 0.03%*
Severe odynophagia 0.1%*
Minor pharyngeal bleeding 0.01%*
Endotracheal tube malposition 0.03%*
Perforation 0.01%*, 0.3%†
Major bleeding 0.03%*, 0.8%†
Mortality 0.004%*
Major morbidity 0.2%*, 1.2%†
Overall complication rate 0.2%*

* From Kallmeyer IJ, Collard CD, Fox JA, et al. The safety of intraoperative transesophageal echocardiography: A case series of 7200 surgical patients. Anesth Analg. 2001;92:1126-1130.


† From Lennon MJ, Gibbs NM, Weightman WM, Leber J, Yusoff IF. Transesophageal echocardiography-related gastrointestinal complications in cardiac surgical patients. Cardiothorac Vasc Anesth. 2005;19:141-145.


From Hilberath JN, Oakes DA, Shernan SK, et al. Safety of transesophageal echocardiography. J Am Soc Echocardiogr. 2010;23:1115-1127.


image

Figure 1-2 Sites of potential injury related to TEE include oral injury (e.g., lip or dental trauma), oropharyngeal injury (e.g., laceration, perforation), laryngeal injury (e.g., vocal cord trauma, compression of airway structures, inadvertent tracheal intubation), esophageal injury (e.g., laceration, perforation, false passage into diverticulum), gastric injury (e.g., lacerations or perforation, particularly of fundus or gastroesophageal junction), and gastric bleeding.


From Hilberath JN, Oakes DA, Shernan SK, et al. Safety of transesophageal echocardiography. J Am Soc Echocardiogr. 2010;23:1115-1127.


image

Figure 1-3 A and B, Probe malposition. Difficulty during probe insertion can be encountered if the TEE probe is lodged into one of the pyriform sinuses. C, In addition to causing mucosal injury to the oropharynx, the TEE probe can occasionally become distorted in extreme flexion. Attempts to withdraw a TEE probe in this configuration before advancing into the stomach and unfolding the kink can lead to severe esophageal injury.


A-C, From Hilberath JN, Oakes DA, Shernan SK, et al. Safety of transesophageal echocardiography. J Am Soc Echocardiogr. 2010;23:1115-1127.


image

Figure 1-4 Gastric probe manipulations. Gastric injury typically occurs in the gastric fundus during deep transgastric probe manipulation, especially when requiring extreme anteflexion to bring the probe in line and in contact with the apex of the heart (e.g., deep transgastric aortic outflow view). The gastroesophageal junction is a vulnerable zone because probe manipulation at this level may place the relatively fixed tissues under considerable tension.


From Hilberath JN, Oakes DA, Shernan SK, et al. Safety of transesophageal echocardiography. J Am Soc Echocardiogr. 2010;23:1115-1127.


image

Figure 1-5 After a CT scan that was diagnostic for aortic dissection, this 67-year-old patient underwent ascending aortic repair, during which diagnostic TEE was performed. There was no premorbid history of symptoms related to esophageal dysfunction. Postoperatively, he became clinically septic. A right pleural effusion was drained and was cultured for a heavy growth of Candida albicans.

Related posts:

  1. Intraoperative Echocardiography for Heart and Lung Transplantation
  2. Epiaortic Ultrasonography and Epicardial Echocardiography
  3. Aortic Valve and Aortic Root
  4. Congenital Heart Disease

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Jun 11, 2016 | Posted by in CARDIOLOGY | Comments Off on Introduction to Intraoperative Echocardiography

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