Cardiology Case #11 (draft)
Primary Author: Dr Alastair Robertson; Co-Authors: Dr Hywel James and David Law
Background:
52yo male presents to ED overnight with an acute onset of central chest pain, radiating to both shoulders. Associtated breathlessness and diaphoresis.
Background of smoking and high cholesterol.
His ECG is below, what do you think?
-
ECG shows a sinus rhythm with a narrow QRS, and normal axis and intervals.
Assessment of ST segments shows ST elevation, as well as hyper-acute T waves in the inferior (II, III, aVF) and lateral (V6) leads. There is reciprocal ST depression in aVL.
This is diagnostic of inferno-lateral STEMI.
There is also ST depression in the antero-septal leads, particularly V1-3 suggestive of concurrent posterior STEMI.
There is subtle ST elevation in I, and the ST elevation in II is greater than in III. Together with lateral ST elevation, this suggests that this is most likely a Left Circumflex occlusion.
In conclusion: infero-postero-lateral STEMI which requires urgent reperfusion.
This patient clearly requires urgent reperfusion therapy, but POCUS can be a powerful tool to:
confirm the diagnosis
assess overall LV function to guide inotropic support
assess for specific complications
Cardiac POCUS:
Below are a Parasternal Long Axis view, a Short-axis view at mid-cavity, and an Apical 4-chamber view.
What regional wall motion abnormalities can you discern?
-
* The parasternal long-axis (first video) can give a key summary of cardiac function. There is no pericardial effusion and mitral and aortic valves appear grossly normal. The overall LV function is moderately impaired
Focus on the LV: the anterior septum (top; LAD territory) is contracting well. The posterior wall (bottom, usually RCA at the base) is impaired.
*The short-axis video (2) is at LV mid-cavity as you can see the papillary muscles on either side (4- and 8-o’clock).
The anterior septum and free wall (approximately 9- to 2-o’clock) are contracting well. The posterior and lateral walls are profoundly hypokinetic (approximately 3- to 8-o’clock).
*In the third video (A4C) focus on the lateral wall (right of screen, LCx territory). It is akinetic with minimal contraction. Compare this to the distal septum and apex (LAD territory) which is contracting well. Notably the septal base is also akinetic (this is inferior territory, usually RCA or LCx)
Basic POCUS:
Assessing LV dysfunction
Ultrasound here confirmed what we expected from the ECG.
There is profound regional wall motion abnormality affecting the posterior, inferior, and lateral walls (infero-postero-lateral STEMI).
LV function is moderately impaired (EF around 40%)
Review the diagram below to remind yourself of the LV territories in different apical views and compare that to the clips above. Remember - - - what is marked as RCA territory is usually RCA, but this is variable, and that around 18% of inferior MIs are due to LCx occlusion.
Review this Apical Long-Axis loop. This is similar to the parasternal long-axis but with better visualisation of the apex. We have slid the probe laterally and inferiorly along the line of the parasternal long axis . The anterior septum and apex (right of frame, LAD territory) is contracting well. Compare this to the posterior wall (RCA or LCx) which is hardly contracting inwards at all (only longtitudinal motion).
Intermediate POCUS:
Assessing for complications of MI
It is important to assess for valvular complications of MI, in particular acute mitral regurgitation. The posterior papillary muscle, which serves the posterior leaflet of the mitral valve has a single blood supply from the PDA and can become ischaemic in postero-inferior MI. This can cause dysfunction of the valve, or even papillary muscle rupture with a flail valve and catastrophic MR.
Review the colour doppler over the mitral valve in PLAX (clip 1), and then Apical Long-axis (clip 2).
Note the MR jet seen in both clips. In clip 2 (apical long-axis) it is easier to appreciate that it is tracking through the posterior (left side) aspect of the valve and onto the posterior wall of the left atrium. This is because the posterior papillary muscle is not functioning correctly.
This mitral regurgitation was felt to be mild-to-moderate ischaemic MR, and unlikely to cause significant haemodynamic compromise.
FOCUS on Mitral Regurgitation:
A quick re-cap on acute severe mitral regurgitation:
Severe MR can be a catastrophic complication of myocardial infarction
Expect to see a hyper-dynamic LV with tachycardia as compensatory mechanism.
In severe MR look for a large MR jet, or eccentric jet tracking round the anterior or posterior LA wall, as well as obvious mitral leaflet dysfunction.
Management priorities: a) target the lowest acceptable BP (remembering that adequate diastolic BP is required for coronary perfusion) by afterload reduction if possible, and b) aggressively treat arrhythmias.
Consider inotropy if required to treat frank cardiogenic shock
Expect pulmonary oedema and high pulmonary pressures, this may require NIV for respiratory support
Early cardiology/surgical intervention, and consider mechanical supports (e.g. ECMO or balloon pump)
Case Conclusion
As immediate PCI was not available the patient was thrombolysed with Tenecteplase. Despite this he had ongoing chest pain and haemodynamic instability with hypotension thus proceeded to rescue PCI.
Angiogram showed an occluded Left Circumflex which was stented with good results.
Hs-Troponin peaked at around 80,000.
Below is his post-PCI ECG.
Note the resolution of ST elevation. T-wave flattening inferiorly, and T wave inversion in lateral leads. Most likely small Q waves inferno-laterally, which are difficult to appreciate given small QRS complexes.
