Tag Archives: aorta

EM Reflections – December 2019

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Thanks to Dr Joanna Middleton for leading the discussions this month

Edited by Dr David Lewis 

Discussion Topics

  1. Cardiopulmonary Resuscitation In Patients With Mechanical Circulatory Support

    • Patient with mechanical circulatory support devices have unique clinical signs of cardiac arrest
    • Understanding the function of these devices ids critical to the management of these complex cases

  2. Aortic Dissection

    • Remains a commonly missed or delayed diagnosis
    • Once diagnosed, meeting the therapeutic goals requires a careful and considered approach

Cardiopulmonary Resuscitation In Patients With Mechanical Circulatory Support

Case

A 70yr male presents with cardiac arrest. He has an LVAD. What are the implications for emergency management and cardiopulmonary resuscitation?

Introduction

Cardiac arrest in patients on mechanical support is a new phenomenon brought about by the increased use of this therapy in patients with end-stage heart failure.

It is important to understand the difference between blood flow and perfusion when assessing any patient with suspected cardiovascular hemodynamic instability, especially patients with an LVAD, in whom the peripheral arterial pulse is not a reliable indicator. Flow represents the forward movement of blood through the systemic circulation. It can be either adequate or inadequate to provide sufficient oxygen delivery to sustain tissue per- fusion. Assessment of adequate tissue perfusion is the most important factor in determining the need for circu- latory assistance such as chest compressions.

What is a Left Ventricular Assist Device?

With an LVAD, blood enters the device from the LV and is pumped to the central aortic circulation, “assisting” the heart.  The outflow cannula is typically anastomosed to the ascending aorta, just above the aortic valve. RA/RV still working

 

Blue Arrow – Important point as patients often present with iGel in place…

 

Unique Patient Properties

  • Pulses often absent
    • BP measured manually with a Doppler – MAP (50-90)
  • SpO2 may not be measurable
  • Anticoagulated
  • Need power!
  • Very reliant on RV function/preload
  • Leading cause of death – sepsis and stroke

Further Reading

Cardiopulmonary Resuscitation in Adults and Children With Mechanical Circulatory Support. A Scientific Statement From the American Heart Association

Aortic Dissection

Aortic dissection remains difficult to diagnosis with 1 in 6 being missed at the initial ED visit. Why? The diagnosis is rare with and incidence of only 2.9/100,000/year, and the presentation is often atypical mimicking other more common diagnoses such as ACS and stroke.

View The SJRHEM  – Aortic Dissection – Resident Clinical Pearl here:

Aortic Dissection

Diagnosis

The most common initial misdiagnoses are acute coronary syndrome, pulmonary embolism, and stroke. Patients with these suspected diagnoses should also be screened for high-risk features of acute aortic dissection. If none are present, they are unlikely to have an acute aortic dissection. If high-risk features are present, balance your clinical suspicion for an aortic dissection with the likelihood of an alternative diagnosis using an approach such as RAPID

How Do I rule Out Aortic Dissection – Just the Facts – CJEM

PoCUS

Early Screening for Aortic Dissection With Point‐of‐Care Ultrasound by Emergency Physicians

A total of 127 patients were enrolled: 72 in the US group and 55 in the control group. In the US group, compared with CTA, the sensitivity of EP POCUS was 86.4%, and the specificity was 100.0%.

 

 

Treatment Goals

From EMCases.com

 

Further Reading

Episode 92 – Aortic Dissection Live from The EM Cases Course

 

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PoCUS – Dilated Aortic Root

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Medical Student Clinical Pearl

James Kiberd

Class 2019 Dalhousie Medicine

Reviewed and Edited by Dr. David Lewis

Case:

A 66 year-old female presented to the Emergency Department with shortness of breath and back pain. She had a known dilated aortic root, which was being followed with repeat CT scans. Given the nature of her presenting complaint, a PoCUS was performed to assess her aorta.

 

 

 

Long Axis Parasternal View:

PoCUS for Cardiac imaging has been studied in the acute care setting; focusing on the assessment for pericardial effusion, chamber size, global cardiac function, and volume status, and cardiac arrest.1

In the setting of acute aortic dissection, further evaluation is often recommended depending on the practitioner’s skill level.2 There have been case reports where ultrasound has been used to assess both Type A and Type B aortic dissections.3–5

In order to assess the aortic root, have the patient in a supine position. Either the phased array or the curvilinear probe can be used depending on examiner’s preference. The probe should be positioned with the marker towards the patient’s right shoulder on the anterior chest to the left of the patient’s lower left sternal border. By tilting the transducer between the left shoulder and right hip, long axis views are obtained at different levels with the goal of identifying four main structures; the aorta, the left atrium, and the right and left ventricles. The parasternal long axis view of our patient is shown in Figure 1, where her aortic root measured 3.83cm.

 

Figure 1: Parasternal Long Axis View of Heart: Patient’s root diameter was found to be 3.83cm.

More generally, this view can be used to assess left ventricular contractility and the presence of pericardial effusion, which were not present in this patient. She went on to have a confirmatory CT scan where her aortic root was found to be unchanged from her last scan and was 3.8 cm in diameter as assessed by PoCUS.

In Summary:

Although not rigorously studied to assess aortic root dilatation at the bedside, we present a case where PoCUS was reliable in the assessment of the aortic root. There have been other cases of aortic dissection identified by ultrasound in the emergency department setting, however confirmatory studies (either CT scan or formal echocardiography) are still recommended.

References:

  1. Labovitz AJ, Noble VE, Bierig M, et al. Focused cardiac ultrasound in the emergent setting: A consensus statement of the American society of Echocardiography and American College of Emergency Physicians. J Am Soc Echocardiogr. 2010;23(12):1225-1230. doi:10.1016/j.echo.2010.10.005.
  2. Andrus P, Dean A. Focused cardiac ultrasound. Glob Heart. 2013;8(4):299-303. doi:10.1016/j.gheart.2013.12.003.
  3. Perkins AM, Liteplo A, Noble VE. Ultrasound Diagnosis of Type A Aortic Dissection. J Emerg Med. 2010;38(4):490-493. doi:10.1016/j.jemermed.2008.05.013.
  4. Bernett J, Strony R. Diagnosing acute aortic dissection with aneurysmal degeneration with point of care ultrasound. Am J Emerg Med. 2017;35(9):1384.e3-1384.e4. doi:10.1016/j.ajem.2017.05.052.
  5. Kaban J, Raio C. Emergency department diagnosis of aortic dissection by bedside transabdominal ultrasound. Acad Emerg Med. 2009;16(8):809-810. doi:10.1111/j.1553-2712.2009.00448.x.
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