Posts Tagged ‘inferior mi differential diagnosis’

The other day my fellow got a call  from surgical ward for emergency ECG opinion for a  suspected Inferior MI .It later turned out to be an acute cholecystitis.

One of the important  anatomical mis-perception  among physicians ,  is to consider  inferior, posterior  and diaphragmatic surface  of heart  as separate entities .They are all  closely linked.In fact, they  more often  mean  the same  anatomical zones !

Heart is a dynamic suspended organ within the middle mediastinum .It  can assume a vertical or horizontal position due to number of surrounding anatomical  and physiological factors. (Diaphragm, Lung , being  important ).The ratio of intra thoracic vs Intra abdominal  volume  &  pressure determine whether the posterior surface of the heart is going to face the back of chest  or simply sit and  rest on the diaphragm .We know a horizontal heart is likely to inscribe q waves  in inferior leads .

acute abdomen diaphragm inferior wall mi cholecystitis pacreatitis

Courtesy : Basic image source from digitallab3d

The  diaphragm can be termed as an  anatomical causeway , that isolates   thorax  from the  abdominal  cavity .Close encounters between the organs separated by this delicate biological  membrane is  always possible .This is especially true for electrical signals  which show little  respect for anatomical barriers .

This is the reason there are too  many abdominal conditions that mimic  inferior MI during a painful  emergency (and vice versa  when inferior  MI mimics  acute abdomen .) In  our  department , we   have witnessed  the following conditions mimicking Infero-posterior ACS.

  1. Acute ascites with polyserositis
  2. Gross obesity with APD
  3. Posterior fat pad ( Necrosis ?)
  4. Thickened pericardium
  5. Minimal posterior pericardial effusion
  6. Diaphragmatic pleurits
  7. Esophageal spasm
  8. Fundal air  trapping and ballooning after a heavy meal !
  9. Acute duodenal ulcer perforation ( With gas under diapharam causing q waves)
  10. Acute cholecystits
  11. Diphragmatic hernia
  12. Achalasia cardia
  13. Pancreatitis

Final message

Do not rush to make a diagnosis of inferior wall MI when  you encounter inferior q waves  with  or without ST /T changes , especially  when the symptoms are atypical .

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We know q waves are not synonymous with Infarct . It just represents electrical activity going away from the electrode.This is why it can occur  even in physiologically in many leads.

Non  infarct Q wave can be recorded with

  • LVH
  • Fibrosis
  • Fluid/Air in beneath  the recording lead
  • Thick chest wall/pericardium (More often Poor  R wave )

rv cavity potential in inferior leads mimicking inferior mi q in

When a chamber enlarges (Any chamber )  it is  brought near the chest wall the electrode may pick up the intra cavity potential that is recorded as q waves .

(The q wave in V5-V6 in severe volume overload of LV may represent LV cavity potential )

Similarly qR complex in severe RV  enlargement  in V1 represent RA cavity potential.Right ventricle is anatomically a difficult chamber to understand. It is located anterior below the sternum  the inferior and posterior aspect of the RV  is facing the diapharagmatic  surface

copd ra rv enlargement mimic inferior mi q waves in 2 3 avf differential diagnosis

In huge RV enlargement , RV cavity potential or( even RA )  can be picked up by limb leads . While cavity potential is well picked up by unipolar pre-cadial leads , it is uncommon for limb lead  record  intracavitory  potential. However  this patient , who was diagnosed  as inferior MI by a  resident ,  turned out to be a clear case of severe  pulmonary hypertension due to  COPD .

Final  message

One  more differential diagnosis for  inferior MI in ECG  exists. A grossly dilated RA, RV due to COPD  with  severe  pulmonary hypertension.

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