Sunday, August 11, 2013

ECG Interpretation Review #73 (LVH – Hypertrophy – Voltage for LVH - Chamber Enlargement)


   The 12-lead ECG shown below in Figure-1 was obtained from a healthy 29 year-old male in for an “insurance physical”.
  • Interpret this 12-lead ECG.
  • Is there voltage for LVH?
  • Would voltage criteria for LVH be satisfied IF this patient was 40 years old?
  • When voltage criteria for LVH are satisfied — What ECG finding best predicts that true chamber thickening/enlargement is likely?
Figure-1: 12-lead ECG obtained from a healthy 29-year old man. Is there LVH? (Figure reproduced from ECG-2014-ePub). NOTE — Enlarge by clicking on Figures — Right-Click to open in a separate window (See text).
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Interpretation of Figure 1:
   There is sinus arrhythmia with a rate range between 65-75/minute. Intervals (PR/QRS/QT) are normal — and the mean QRS axis is normal (+50 degrees).
  • Whether or not voltage criteria for LVH are satisfied on this tracing depends on the age of the patient.
  • QRST Changes: A small q wave is seen in leads I and V6. R wave progression is normal (with transition between V2-to-V3). Other than minimal ST-T wave flattening in leads III, aVF — ST-T waves are unremarkable. There are no acute changes.
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Voltage Criteria for LVH: Which Criteria to Use?
   The ECG in Figure-1 provides an excellent example for illustrating two important concepts: i) Many criteria exist for assessment of LVH; and ii) Some of these criteria are age-dependent.
   Universal agreement on how to assess for LVH on ECG is lacking. How can there be agreement? — when more than 50 sets of criteria for LVH have been published in the literature. Practically speaking — none of these 50-plus criteria are optimally accurate. All suffer from imperfect sensitivity, which is no better than 55% by even the best of electrocardiographers. This means that up to half of the time when LV (Left Ventricular) thickening or LV chamber enlargement is present beyond the normal adult range — that it will not be detectable based on ECG assessment. BOTTOM Line: IF you truly need to know clinically about chamber enlargement — then get an Echo.
  • Despite the poor sensitivity of ECG for picking up true chamber enlargement specificity of the ECG may be excellent (ie, >90%) — IF in addition to adequate voltage for LVH, the patient also manifests ST-T wave abnormalities consistent with LV “strain” (See below).
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Which of the 50 Criteria for LVH to Use?
   Our answer as to which LVH criteria are best admittedly reflects our bias, which is based on our years of experience aiming to optimize sensitivity/specificity in ECG assessment. We feel LVH criteria can be greatly simplified by just remembering two numbers = “35” and “12”. Use of these 2 numbers readily identifies up to 90% of patients with LVH when it is possible to do so on 12-lead ECG (Figure-2):
Figure-2: Simplified voltage criteria for LVH (Figure reproduced from ECG-2014-ePub).
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Regarding Figure-2:
  • Only one voltage criterion (ie, 35 or 12 ) — needs to be satisfied for ECG diagnosis of LVH.
  • Use of the criterion for R in aVL ≥12mm is likely to be most helpful when there is left axis deviation (Use of this criterion with an R wave ≥12 in aVL may diagnose LVH despite minimal voltage in V1,V2 and V5,V6).
  • Note that voltage criteria for LVH may not be valid for younger patients. This is because younger adults (in their 20’s) often manifest increased QRS amplitude without true chamber enlargement. We suggest not using these criteria for patients less than 35 years old.
  • The accuracy (specificity) for the ECG diagnosis of LVH can be greatly increasedIF in addition to satisfying one or more voltage criteria, ST-T wave changes of "LV strain" are also present (See Figure-3 below).
  • The Clinical History helps in assessing for LVH. It is good to know that even before looking at the ECG itself — the chance of true chamber enlargement is greatly increased IF the tracing is from a middle-aged, African-American man with longterm hypertension. A history of underlying heart disease (heart failure, hypertension, cardiomyopathy, valvular disease, coronary artery disease) clearly increases the likelihood of LVH in any given patient. On the other hand, the history in this case of a healthy, asymptomatic 29 year-old male — makes true LV chamber enlargement far less likely.
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Additional Voltage Criteria
   No single voltage criterion will identify all patients with LVH. As a result — we occasionally turn to additional voltage criteria. We favor any of the following:
  • A deep S wave (≥20-25 mm) in lead V1 or V2.
  • A tall R wave (≥25 mm in V5or ≥20 mm in V6 ).
  • An R wave ≥20 in any inferior lead (II, III, or aVF ).
  • Cornell Criteria — LVH is present IF sum of R wave in lead aVL + S in V3 is ≥20mm (female) or  ≥28mm (male).
  • Bottom Line: In our experience, IF all you remember are the numbers ‘35’ and ‘12’ for LVH voltage criteria — then ~90% of the time when it is possible to diagnose LVH on the ECG of an adult, you will be able to do so!
  • Satisfying any of the above additional criteria should help to pick up most of the remaining ~10%.
  • Incorporating Clinical History and looking for “strain” or a strain “equivalent” — will further refine and increase accuracy (specificity) of your diagnosis.
  • Keep in mind that competing conditions (ie, hyperkalemia, acute infarction, conduction defects, pulmonary disease) — may mask ECG diagnosis of LVH.
  • IF you really need to know about chamber size — Get an Echo. The ECG is simply not optimally accurate.
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LV “Strain” Recognition/Use in Diagnosing LVH
   It is difficult to define “strain”. We describe it as — a pattern of asymmetric ST-T depression (Panel C in Figure-3). Perhaps “strain” simply reflects that point of anatomic ventricular enlargement at which increased demand (from chamber thickening) outstrips blood supply — with resultant ST‑T wave repolarization changes from suboptimal perfusion. Or perhaps not … That said — What counts clinically is ECG recognition of a “strain” pattern.
  • Note how downslope of the ST segment is slower with “strain” (arrow in Panel C of Figure-3) — compared to more rapid return of the ST segment to baseline.
Figure-3: ST-T wave appearance of normal (A) — vs “strain” (Cor a strain “equivalent” (B) — vs ischemia (D). (Figure reproduced from ECG-2014-ePub).

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   LV “strain” is most commonly seen in one (or more) leads that look at the left ventricle.
  • These include lateral leads I,aVL; V4,V5,V6.
  • Less often — LV “strain” may be seen in the inferior leads (especially if the patient has an inferior axis).
  • LV “strain” — is generally not seen in anterior leads (V1,V2,V3 ). In contrast, RV “strain” (as may occur with RVH or acute pulmonary embolus) — typically is seen in either anterior or inferior leads.
   The concept of pattern recognition is essential to ECG diagnosis. Consider the following:
  • With ischemia (seen in Panel D of Figure-3) — there will often be symmetric T wave inversion in two or more leads in a general lead area.
  • As one traces the path from a normal ST-T wave (Panel A in Figure-3) — to the asymmetric ST-T wave typical of LV “strain” (seen in Panel C) — one passes through an intermediate stage, where the ST-T wave flattens with beginning ST depression (Panel B). We designate this intermediate stage as a strain equivalent”.
   The reason it is important to recognize “strain” — is that this finding greatly increases the accuracy of the ECG diagnosis of LVH.
  • The presence of increased voltage without “strain” — has low specificity (<50%) for true chamber enlargement (especially if there is no underlying heart disease). We interpret the finding of increased voltage without ST-T wave changes of “strain as “Voltage for LVH”. This designation serves to acknowledge that despite voltage — statistical likelihood of true chamber enlargement is low.
  • Clinical implications of LVH voltage plus a “strain equivalent” (ie, nonspecific ST-T wave flattening, as seen in Panel B of Figure-3) — are the same as they are for “strain” (greatly increased specificity for LVH and an up to 8-fold increased morbidity/mortality as was shown in patients with longstanding hypertension in the Framingham study).
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RETURN to this Case:
   The patient in this case was a healthy, asymptomatic 29 year-old man in for an “insurance physical”. In Figure 4 — We blow-up precordial leads V1,V2 and V5,V6 from Figure-1 to illustrate how we assess to determine if voltage criteria for LVH are present. We focus on precordial leads in this case — since lead aVL in Figure-1 was clearly below the required 12mm amplitude.
Figure-4: Blow-up from Figure-1 to illustrate how QRS amplitude is counted. (Figure reproduced from ECG-2014-ePub).
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Regarding Figure-4:
  • The deepest S wave in V1,V2 is in V1 (20) + the tallest R wave in V5, V6 (= 23 in V5) is >35 — so voltage criteria for LVH would be satisfied IF the patient was older than 35 (Figure-2). But because the patient is less than 35 years of age — voltage for LVH is not present.
  • Regardless of whether the patient in this case is 29 or 40 years old — there is no indication of “strain” in any of the lateral leads in Figure-1. Thus, even IF the patient was over 35 — true LV chamber enlargement would be unlikely in this asymptomatic individual without ECG indication of “strain” or a “strain equivalent”.
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LV “Strain” It’s Effect on Specificity for LVH Diagnosis
   Once “strain” and voltage for LVH are both present — specificity for LVH dramatically increases (up to ~90% and >95% if the patient has underlying heart disease). This is seen in the precordial leads shown in Figure-5:
Figure-5: Illustrative precordial leads obtained from an older adult with long-standing hypertension. QRS amplitude is markedly increased — easily satisfying voltage criteria for LVH (Figure-2). In addition — note ST-T wave changes consistent with LV “strain” in leads V4,V5,V6 (Figure-3). Specificity for LVH is virtually 100%. (Figure reproduced from ECG-2014-ePub).
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- For more information – GO TO:
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  • See also ECG Blog #75 - for review of Atrial Enlargement/Abnormality -
  • See ECG Blog #77 - for review of RVH criteria -
  • See also ECG Blog #92 ( = Basic Concepts #5) — for another approach to LVH.
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2 comments:

  1. Yeah It's good I appreciate this article. I recommand it to my friends,I,ll be back here again and again . Visit our blog for more .

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  2. Many times I see older patients with Htn/underlying heart condition with strain patterns when ekgs done on routine basis but not enough voltage to call it LVH.. Do we call such patterns strain patterns?? can it be lateral wall ischemia as these older patients seem to always have mild exertional if not at rest breathlessness ('Chronic' breathlessness)or is this a benign finding for such old patients???

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