Posts Tagged ‘non infarct q waves’

Q waves are  neither  sacred  nor sinister waves . It represents   either of the  following .

  1. Electrical activity that goes away from the recording electrode.
  2. Or whenever there is a  electrical insulation or hurdle that interrupts the flow  of current  towards the electrode ( and if it is sustained )  it  can result in q waves (Minor interruption produces  a notch or  slurs . Please note a major slur becomes a q wave equivalent  )

Here is young women of 42 years with  a diagnosis of  old  anterior MI for   over 5 years ( Getting a dedicated care from a cardiologist!  The prescription included Imdur/Betaloc/ Statin/Clopidogrel and Aspirin )

This was the ECG . It was very convincing for  old ASMI.

epicardial fat and poor r wave in v 1 v 2 v3 q  waves

It  happened ,  I did an echo for her .

epicardial fat and q waves in ecg pesudo infarct non infarct 2  q

She lacked wall motion defects even after a meticulous search .  Instead   she had a   good layer of epicardial fat measuring 9 mm .That was more localised in  anterior wall extending little to LV apex.Her EF 65 % .

*She was a  fairly obese (not gross )  individual with a BMI of 34 .The fat pad thickness was not that huge  , I thought , still it was producing the q waves . I  have seen much thicker fat pads with good R waves in ECG . I  wonder ,  is it the type of fat that adds up to electrical insulation ?

This patient was sent back to me  again  for ruling out ASMI .  Echo was  done  two weeks  later . No evidence for  ASMI  could be detected.

epicardial fat and q waves in ecg pesudo infarct non infarct fat 2  q

What is the normal thickness of epicardial fat pad ?

It is less than few mm . Exact normality is not known .(Empirically < 5mm ) it is very rare for fat deposition  in infero posterior aspect , except in morbid obesity.

What is the function of epicardial fat ?

  • Long considered inert . Now , found to be a metabolically  active lipid pool.
  • We also know  heart  consumes more fatty acid than an other organs for moment to moment energy consumption .
  • Inflammatory mediator in atherosclerosis ?
  • It may also act as a mechanical cushion effect along with pericardium
  • Rarely fat infiltration can compress the heart and may result in restrictive  AV filling defects in doppler  .(May explain the unexpanded dyspnea  in many obese patients )
epicardial fat a dynamic depot athreosclerosis

Role of epicardial fat depot in the genesis of atherosclerosis

Subcutaneous vs  Epicardial fat.

We know thick chest wall can also interfere with ECG. Epicardial fat is more likely to record  q waves than  sub cutaneous fat ,  as the insulation is more closer to heart in epicardial fat . In thick chest wall current leaks from heart and  well scattered  hence  poor R wave is more common in such situations rather than q waves !

Following things can generate  q waves (Other than Infarct  )

  1. Fibrosis-Myocardial /Interstitial
  2. LVH
  3. Thickened pericardium
  4. Thick chest wall/ Epicardial fat
  5. Air/Fluid in pericardial space

Final message

In obese men and women  anterior Q wave can be  misleading .Such  medical errors can be so convincing .

After thought

If epicardial fat can  extinguish   R waves  and  replace it with  q waves  , these  innocuous  looking fat pads has every reason to  influence the ST segment shifts during  an episode  of ACS  as well !  .  Isn’t ?  . If so  . . . how reliable is  our ECG criterias  to diagnose  acute coronary syndromes  in grossly obese men and women ?

Read Full Post »

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.

Read Full Post »

Looks very much a infarct of  infero posterior territory is it not ?

Have a look at her 2D echo still picture . . .

Are you convinced ?

This women had normal LV systolic and diastolic function with no evidence of constriction.

The explanation for the asymptomatic pericardial thickening is due to a healed  chronic pericarditis .This sort of localised thickening in the posterior aspect is all the more likely following a loculated pericardial effusion.Tuberculosis is a very likely etiology.But this women do not have any markers for tuberculosis.Since she is symptomatic no treatment was offered.She is being followed up.

Discussion .

Q waves are not ” sacred waves” to diagnose myocardial infarction.It simply indicates the  direction of current flow is away from the  recording lead of the ECG .Any thing  electrically inert , that come in the interface between the heart and the recording electrode   can record a q waveWhat are the pathological entities that can produce q waves other than infarct ?

  • Fibrotic myocardium(DCM-Cardiomyopathy)
  • Myocardial Scars
  • Myocyte dis array(LVH, HCM)
  • Air,fluid in pericardium /pleural space
  • Pericardial thickening (As in this patient)
  • Electrical shortcircuits (WPW syndrome)
  • Rarely pure ischemia without necrosis can produce q waves (Electrically stuned myocardium)

Final message

Localised pericardial thickening is  a rare  (?unrecognised) cause for pathological q waves , that may mimic a MI.

Read Full Post »