Nicole Kupchik

Author, Independent Clinical Nurse Specialist & Educator

Critical Care Consulting | Quality Improvement/Program Development | Critical Care Education | Certification Reviews

Those of us that have worked in cardiac care have seen changes in the management of myocardial infarctions.  As we have changed our protocols and treatment regimens, we have drastically decreased mortality.  Much of this decrease in mortality has been attributed to better higher quality CPR and a stronger focus on door to balloon time in the cath lab.

 

The Why of EKG changes:

Myocardial infarctions arise from a lack of blood flow from the coronary artery to the myocardial tissue.  The elevation of the ST segment on the EKG shows the changes in electrical perfusion throughout the heart.  As tissue is injured, electrical signals have to reroute around the damaged area or are delayed through the injured tissue.  This causes the changes in the ST segment on the 12 Lead EKG.

 

The skinny on the Right Ventricle:

Venous blood returns from the inferior and the superior vena cava and unloads into the right atrium to the right ventricle.  About 85% of blood flow is supplied to the inferior wall by the right coronary artery and about 15% from the left circumflex artery.

The right side of the heart is a low pressure system.  Normal right atrial pressure is about 2 – 6 mm Hg, while normal right ventricular systolic pressures are 15 – 20 mm Hg over diastolic pressures of 0 – 5 mm Hg.  In the past, right atrial pressure was used to guide fluid status & resuscitation.  However, stroke volume is a better measure of fluid responsiveness.  **Clinical pearl** Remember that pressure does not equal volume.  It is only an assumption of volume (i.e. measuring the CVP).

As blood leaves the right ventricle, it then enters the pulmonary system to get oxygenated.  The right ventricle must have enough strength to overcome pulmonary pressure and enough volume to move forward.

 

Watch this video for an in-depth conversation about RV Infarction:

 

Right Ventricular Infarct:

Injury or ischemia to the inferior wall is diagnosis by leads II, III, and aVF on the 12 Lead EKG.   It is estimated that 30 – 50% of inferior MIs have RV involvement.

A right-sided EKG can be performed by moving the precordial leads to the right side of the chest.  This creates V1R, V2R, V3R, V4R, V5R, and V6R.

In this placement, the clinician gets a look primarily at the right ventricle and then gains reciprocal look at the left ventricle.  V4R has a sensitivity of 88%, specificity of 78% and diagnostic accuracy of 83% in the diagnosis of RV Myocardial Infarction.  V4R may be elevated, but the contiguous leads may not be elevated.

Another key finding is in inferior wall & RV infarctions is that Lead III often has more ST elevation than Lead II.  Lead III is a better monitoring lead in acute coronary syndrome. 

 

Why is Preload important in the RV Infarct patient?

When the ventricle is experiencing a myocardial infarction, it becomes hypokinetic or even akinetic.  Stroke volume is not moving forward to the lungs and to the left side of the heart.  Since the ventricle is losing contractility, optimizing stroke volume is key.

For years we were taught to give Nitroglycerin or Morphine when patients experience chest pain.  However, these are both preload vasodilators.  Preload vasodilators reduce stroke volume by dilating both the vena cava and the ventricle itself.  The ventricle no longer senses the “stretch” of being full making it less contractile.  Patients at this point become more hypotensive and develop further signs and symptoms of shock.

 

RV Infarct Treatment Plan:

So what is the treatment plan?

  1. Early Percutaneous Cardiac Intervention (PCI)
    1. Consider mechanical support during or post PCI
      1. Impella or IABP Support
      2. VAD Support
  2. Fluid Optimization
    1. How do I know how much to give and when?
      1. Minimally invasive or Non-invasive measures
        1. Pulse Pressure Variation
        2. Passive Leg Raise
        3. Bioreactance Cardiography
        4. Arterial Line Technologies
  3. Continuous EKG Monitoring
    1. Arrhythmias can happen if blood supply is cut off to the Sinus or the AV Node
      1. Bradyarrhythmias – Sinus Node
      2. AV Blocks – AV Node
  4. Tachyarrhythmias in response cardiogenic or hypovolemic shock
    1. Atrial Fibrillation may occur due to ischemia of the right atrium
      1. PROMPT cardioversion should be considered to restore AV synchrony
  5. Inotropic Therapy **ONLY AFTER FLUID OPTIMIZATION**
    1. Dobutamine (may initially cause hypotension)
    2. Epinephrine (more severe shock phases)
    3. Milrinone (may cause more hypotension initially)
    4. Dopamine (probably not the drug of choice due to arrhythmogenic effects)
  6. Vasopressor therapy
    1. Norepinephrine
    2. Vasopressin
  7. Inhaled Nitric Oxide (if the patient has developed RV Failure)
    1. Pulmonary Vasodilator.
    2. Reduces pulmonary vascular resistance
  8. Intra-aortic balloon pump
    1. Reduces afterload on left side of heart
    2. Increases coronary perfusion
  9. Ventricular Assist Device
    1. Improve flow and emptying of Right Ventricle
      1. Tandem Heart ®
      2. Impella RP ®
      3. Centrimag ®

 

Summary

When a patient presents with a MI, it is important determine the type and location of injury for diagnosis and intervention.  When we see a patient with Acute Coronary Syndrome, immediately giving Nitro or Morphine, may drastically increase complications if the patient is experiencing a RV Infarct.  AVOID anything that drops preload!  Fluid is your go-to!

Performing a right-sided EKG whenever an inferior MI is diagnosed, provides healthcare workers with an accurate diagnosis and plan for treatment.  Patient’s experiencing a RV Infarct have a complicated course of treatment.  Early cath lab intervention is the key to correct the problem, but further support may be needed to help the weakened Right Ventricle.

by Joel M. Green MSN, RN, CCRN-CSC, CMC

 

References:

Dima, C., Pershad, A.,  & Coven, D. L. (2017)  Right ventricular infarction treatment & management.  Retrieved February 21, 2018 from https://emedicine.medscape.com/article/157961-treatment#d10

FeelGuide (2017).  Banner Image.  Retrieved February 21, 2018 from http://www.feelguide.com/page/686/

Inohara, T., Kohsaka, S., Fukuda, K., & Menon, V. (2013) The challenges in the management of right ventricular infarction.  European Heart Journal – Acute Cardiovascular Care.  September 2013.  2(3). 226 – 234.  Retrieved February 21, 2018 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3821821/

Right Ventricular Infarct.   Retrieved February 21, 2018 from https://lifeinthefastlane.com/ecg-library/right-ventricular-infarction/

 

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