LVOT Opening in Cardiac Arrest

:VOT Opening

Association between left ventricular outflow tract opening and successful resuscitation after cardiac arrest

Resuscitation May 2019 - Pubmed Link


Take Home Points

1. In this small case series, an open left ventricular outflow tract, as seen on TEE, was associated with successful resuscitation.

2. Although not definitive, this evidence supports the use of TEE to guide cardiac arrest management.


Background

In case you haven’t heard, transesophageal (aka transOesophageal) echocardiography (TEE) is being used in cardiac arrest patients. There is slowly mounting evidence that this is a good thing. Among the touted benefits are 1) No need to interrupt chest compressions for images → can potentially decrease pause times 2) Can more readily identify causes for the arrest and 3) Can monitor if chest compressions are actually occurring in the right place over the heart. This last one would be a big problem. We know that chest compressions are one of the few useful interventions in cardiac arrest. There is evidence to suggest that a lot of the time compressions are in the wrong place and actually impeding flow to the heart and brain! To date, aside from a plethora of anecdote, there is not much data supporting this third benefit of TEE, except for maybe this pig study. This study is a big step. Humans. In cardiac arrest. What echocardiographic signs matter for survival?


Check out The Evidence Atlas - Echo for a review of prior evidence on point of care ultrasound in cardiac arrest.


Question

Can echocardiographic parameters measured on TEE during cardiac arrest correlate with survival?


Population

Single tertiary referral center in Italy


Inclusion:

  • Out of hospital cardiac arrest (OHCA)

  • Met criteria for extracorporeal cardiopulmonary resuscitation (ECPR)

  • Time from event to CPR < 6 minutes

  • Absence of major comorbidities or terminal illness

  • 20 minutes of ACLS without ROSC

  • Expected time from event to hospital arrival <65 minutes

  • Mechanical ventilation


Exclusion:

  • Trauma


Design

Retrospective cohort study of consecutively admitted patients


All patients presented to the emergency department in cardiac arrest (meeting criteria above).

They then all got a focused TEE exam which included measurements of the right ventricular outflow tract (RVOT) fractional shortening (see below for more details on the scan).

They all were put on venous-arterial ECMO (that's what they said but it turns out only 79% were based on what is reported in results).

They all underwent emergent coronary angiography.

Standardized post-resuscitation care targeted temperature management, sedation, inotropes as needed.


Primary outcome was to see if TEE variables were associated with successful resuscitation, defined as the return of electro-mechanical activity (REMA) or ROSC.

Return of electro-mechanical activity (REMA) defined as return of QRS complexes associated with LV systolic shortening of at least 5 mm. They used ROSC if the patient was not on ECMO.

Survival analysed with Kaplan-Meier analysis

Surivors were called Group-SUXX Non-survivors were called Group-FAIL


Who did the ultrasounds?

An ICU physician, expert in echocardiography


The Scan

TEE transducer

TEE


“Fast-focused 2D TEE exam” - looking at heart and ascending aorta for etiology of arrest (specifically to rule out aortic dissection). Chest compressions continued during introduction of probe and examination.


They measured a bunch of things:

  • RVOT fractional shortening

  • RV fractional area change

  • LVOT diameter

  • Aortic root diameters and position of the ascending aorta

  • LV volume and ejection fraction (modified Simpson’s rule)


Learn how to do Focused TEE in Cardiac Arrest from 5 Minute Sono!

5minsono


Check out TEE Pathology on the POCUS Atlas!

thePOCUSAtlas


Results

N = 19

  • Average age was in 50s

  • Similar baseline characteristics between groups (survivors vs non-survivors), even regarding no flow and low flow time, bystander CPR, shockable rhythm, and ECMO

  • No significant difference in need for coronary revascularization

  • 79% had mechanical compression device

  • No patients had pre-existing cardiac disease

  • 79% ECPR

  • 7 patients (37%) survived with REMA or ROSC (Group SUXX)

  • 6 patients (32%) survived to 24 hours

  • 1 patient (5%) survived to discharge


Primary Outcome - Echo parameters that were different between groups

Group SUXX - 100% had open LVOT whereas only 1 patient (8%) in Group FAIL had open LVOT


EF significantly higher in Group SUXX (60 vs 47%)


Ascending aorta slightly larger in Group SUXX (but only 2.3 cm vs 1.5 cm)


Other Findings

Hazard ratio for LVOT opening 0.205 (CI 0.05-0.794)

  • Compared to hazard ratio of mechanical chest compression 3.15 and no flow time 0.872.


Patients in Group SUXX had longer survival after arrest 35 hours vs 6 hours. Two patients in group SUXX became organ donors.

Most other parameters were not statistically different between groups (RVFAC, RVOT-fs, aortic diameter at annulus and sino-tubular junctions, LVEDV, LVESV, EF)


Average time from arrival to TEE was 8 minutes

TEE insertion was not difficult and did not impede resuscitations.

RV compression also occurred during compressions.


Limitations

Usual stuff - super small population, performed in Europe, single highly skilled operator, retrospective.

These measurements do not sounds like part of a “focused” TEE exam. Hard to image doing these complex measurements in real-time unless you have someone dedicated to only doing TEE during the arrest. This is likely not feasible in many places that do TEE, let alone most places that don't have TEE.

This seems a rather low survival rate (5%) for a highly selected group of cardiac arrest patients.

Survival endpoint. This is always a problem in cardiac arrest research. If only 1 patient in the study made it out out of the hospital, can we really say one group was better than the other? Or are we going after increasing survival for more organ donors as is suggested in this paper?


Discussion

If the LVOT was closed during those resuscitations - why didn’t they move compressions?! Live and learn I guess. In the real world, if you see LVOT compression, you move the compression over the LV to fix the problem. Unclear what they did in this case. If they did not move them - that is sad for the patients. If they did move them - that is sad for this study because it adds another wrench in the data interpretation.

Should we move standard hand position during CPR more towards the feet? Or is this evidence that we need TEE to individualize hand position? We need more studies to figure this out.


Take Home Points

1. In this small case series, an open left ventricular outflow tract, as seen on TEE, was associated with successful resuscitation.

2. Although not definitive, this evidence supports the use of TEE to guide cardiac arrest management.


More Great FOAMed on this Topic

EMCrit- Felipe Teran on Why We are Doing CPR Wrong

The Resuscitative TEE Project


Our score

3 Probes


Expert Reviewer for this Post

Wilson

Casey Wilson, MD, RDMS @CaseLWilson

Emergency Ultrasound Director and Fellowship Director at Grand Strand Medical Center in Myrtle Beach, SC, an affiliate of USC


Reviewer's Comments

While this article lends some promise to the utility of TEE in non-traumatic arrests, it’s difficult to extrapolate to most clinical settings given how comprehensive and aggressive this arrest algorithm was (TEE, ECMO, post-ROSC cath, targeted temp mgt, etc). The fact that it excluded people with significant comorbidities and that none of the patients had underlying cardiac disease makes this population atypical from what most of us are seeing in our shops. Regardless, it continues to support the utility and feasibility of TEE in an arrest setting – but the non-ICU-super-user-everyday-TEE folks might find these measurements daunting.


Cite this post as

Michael Prats. LVOT Opening in Cardiac Arrest. Ultrasound G.E.L. Podcast Blog. Published on September 30, 2019. Accessed on November 13, 2019. Available at https://www.ultrasoundgel.org/77.
Published on 09/30/19 06:00 AM
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