Vitals during an MI

  1. 0
    I have yet to get a clear answer on this or maybe there isn't one. What generally happens to BP and Pulse during a Heart Attack? I have heard that the BP may increase or decrease, but is it generally one more than the other? it sort of depends on the physiology and cause. Is there a general rule of thumb though?

    Thanks!
  2. 8 Comments so far...

  3. 3
    No ... a number of variables and any number of underlying causes of infarction mean there is no rule of thumb.
    sallyrnrrt, Vespertinas, and CCL RN like this.
  4. 2
    It depends on the type of heart attack (ie what part of the heart it affects). In most cases, the heart rate will increase. This is attenuated by the fact that most people who have an MI will also be on a beta blocker already. In terms of blood pressure, it depends on the area of the heart involved and how severe the MI is. A massive LAD or L main MI (anterior MI) will cause severe hypotension (cardiogenic shock). The treatment is quite different for RCA infarcts. Inferior or posterior MIs (RCA infarcts and sometimes infarcts of branches off of the LCx) can, but less often cause hypotension. However, these types of MIs are very, very sensitive to pre-load so any medications that either decrease cardiac output or change pre-load will cause hypotension. Less severe MIs will often be associated with hypertension. This is actually a pretty good prognostic sign as it shows that the pumping function of the heart is preserved.
    Vespertinas and GinaCat like this.
  5. 1
    Any MI may cause hypotension if it covers a large enough area of muscle and is an indicator of prognosis I disagree with wowza and I have found inferior and true posterior (right ventricular) wall MI are more likely to cause hypotension as they affect the "pumping chamber" of the heart the left ventricle.

    "Certain clinical features (the hypotension, bradycardia, and heart block) would all be compatible with RVMI. "
    Management of Acute Myocardial Infarction With Hypotension*
    Vespertinas likes this.
  6. 1
    Inferior MI's with right sided involvement will generally cause hypotension. That's because it's affecting the part of the heart that pumps blood to the rest of the body. If they're beta-blockers, their HR will stay in the 60-80 range and they can't compensate for a drop in BP. Any MI can cause hypotension since they all affect the heart and the hear has to be working to pump anything out. I know we're cautious with nitro in an inferior MI because if the additional drop in BO.
    Vespertinas likes this.
  7. 1
    Quote from Esme12
    Any MI may cause hypotension if it covers a large enough area of muscle and is an indicator of prognosis I disagree with wowza and I have found inferior and true posterior (right ventricular) wall MI are more likely to cause hypotension as they affect the "pumping chamber" of the heart the left ventricle. "Certain clinical features (the hypotension, bradycardia, and heart block) would all be compatible with RVMI. "Management of Acute Myocardial Infarction With Hypotension*
    Esme, I probably should have qualified my statement. RV infarcts can cause hypotension but are much easier to correct and usually much more benign than LV infarcts*So hypotension in an anterior MI means the pump failed. Hypotension in an RV infarct is often a pre-load issue that can quickly be corrected. Anterior infarcts causing hypotension can be corrected only with some pretty extreme interventions because the pump has failed- balloon pumps or inotropes until the initial stunning of the myocardium is corrected. Even then, often teh scarring is so severe you get an ischemic cardiomyopathy. It is rare to get an ischemic cardiomyopathy from an RV infarct unless a left dominant circulation with a massive infarct. Now the above is also dependent on the anatomy. If the patient is left dominant, the LCx will probably be the occluded vessel so it will be assocaited with inferior or lateral changes in addition to posterior changes. This means a large portion of myocardium will be involved and actually will involve portions of the LV, rather than just the RV. With regard to the bradycardia or heart block, these too are usually short lived and resolve with reperfusion of the AV node.
    Vespertinas likes this.
  8. 0
    What about the pulse pressure with an MI? would it be narrow or wide?
  9. 4
    Quote from silverhalide
    What about the pulse pressure with an MI? would it be narrow or wide?
    More than likely narrow. The most common cause of a narrow pulse pressure is a drop in left ventricular stroke volume. Other causes include hypovolemia, shock, cardiac tamponade and aortic valve stenosis.

    I also wanted to chime in regarding vital signs changes during an MI...it depends on where the MI is located and how extensive the damage is.

    * Anterior MI (LAD) - tachycardia, SA blocks, pulmonary edema
    * Inferior MI (RCA) - bradycardia, hypotension. They may also present with N&V and hiccups instead of chest pain. Anytime you have an inferior MI, do a right-sided EKG to check for RV involvement.
    * Lateral (LCA, LCX) - ventricular dysrhythmias
    * Septal (LAD, RCA) - tachycardia, atrial fibrillation
    * Posterior (LCA, LCX, RCA) - bradycardia, junctional rhythms
    * RV infarct - suspected with inferior MI, which is why if a patient presents with an inferior MI they need to have a right-sided EKG completed. Look for changes in V4R. The incidence of RV involvement is 40% with inferior wall MIs. You'll see hypotension, JVD and lungs CTA in a true RVMI.
    chyna016, VidaUrbana, PatchycatRN, and 1 other like this.
  10. 0
    Thanks!


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