Heart pearls! » ECG http://www.heartpearls.com For all cardiology enthusiasts! Bonjour! Click on the title above to go to site index so that you can browse the articles! Tue, 07 Feb 2012 02:51:29 +0000 en hourly 1 http://wordpress.org/?v=3.2.1 ECG- Sgarbossa criteria- to diagnose AMI in LBBB http://www.heartpearls.com/2009/07/ecg-sgarbossa-criteria-to-diagnose-ami-in-lbbb.html http://www.heartpearls.com/2009/07/ecg-sgarbossa-criteria-to-diagnose-ami-in-lbbb.html#comments Sat, 25 Jul 2009 18:34:41 +0000 Dr Jayachandran Thejus MD http://www.heartpearls.com/?p=474
  • 5 points for concordant 1 mm ST elevation. (any lead)
  • 3 points for concordant 1 mm ST depression in v1 to v3
  • 2 points for discordant 5 mm ST elevation. (any lead)
    • Score of 3 predicts AMI.
    ]]>     http://www.heartpearls.com/2009/07/ecg-sgarbossa-criteria-to-diagnose-ami-in-lbbb.html/feed 0     ECG- AV block http://www.heartpearls.com/2009/07/ecg-av-block.html http://www.heartpearls.com/2009/07/ecg-av-block.html#comments Fri, 24 Jul 2009 12:40:56 +0000 Dr Jayachandran Thejus MD http://www.heartpearls.com/?p=467 Third degree AV block

    • May be isoarrhythmic- similar P and QRS rates.
    • Acute-
      • At AV node level- inferior wall MI, digoxin and rheumatic fever.
      • At bundle branch level- anterior wall MI.
    • Chronic-
      • Commonest cause- fibrosis (Lev, Lenegre)
      • Congenital (maternal anti-Ro antibodies)
    • Chronic third degree HB is usually due to damage to both right and left bundle branches.
    • When difficulty in distinguishing third degree HB from second degree HB-
      • QRS intervals are usually regular- if irregular usually suggests some amount of AV conduction.
      • Constant PR (or flutter-R) interval indicates second degree HB while varying PR (or flutter-R) interval indicates third degree HB.

    Location of AV block

    • Sites-
      • AV node- most common
      • His bundle- rare (so differentiation is between the other two)
      • Bundle branches- second most common
    • With blocks lower than third degree heart blocks-
      • QRS duration-
        • Normal- AV node
        • Wide- can be either (AV node + aberrancy can also cause widening)
      • PR interval consistency-
        • Variable PR interval- AV node (only AV node has ability to vary conduction time)
        • Constant PR interval (when AV conduction is present)- bundle branch

    Wenckebach sequence

      • Indicates AV nodal block
      • PR interval-
        • Progressive prolongation of PR interval – because successive atrial impulses arrive progressively earlier in the relative refractory period of the AV node.
        • The “increase in PR interval” (PR2-PR1, PR3-PR2 etc) progressively decreases and hence is maximum between the second beat and the first beat. This, in the setting of a constant PP interval, causes RR interval to shorten progressively.
      • RR interval-
        • RR interval progressively shortens.
        • Longest cycle (with the missed beat) is less than twice the shortest one. This is because the longest cycle has the shortest PR interval beat.
        • Smaller QRS groups are commoner than larger ones. Thus, 3:2 > 4:3 > 5:4 etc. Commonest is pairs.
      • PP interval- constant.

    Purkinje block (in bundle branches)

      • Second degree heart block-
        • Purkinje cells have very short refractory period. So, either normal PR or no conduction. No increased PR interval.
      • Complete heart block-
        • Almost always, preceding bundle branch block is present.
        • Usually there is sudden transition from no heart block to complete heart block without an intervening first or second degree heart block.
    ]]>     http://www.heartpearls.com/2009/07/ecg-av-block.html/feed 0     ECG- Decreased automaticity leading to bradycardia http://www.heartpearls.com/2009/07/ecg-decreased-automaticity-leading-to-bradycardia.html http://www.heartpearls.com/2009/07/ecg-decreased-automaticity-leading-to-bradycardia.html#comments Wed, 22 Jul 2009 11:47:43 +0000 Dr Jayachandran Thejus MD http://www.heartpearls.com/?p=452
  • Physiologic slowing of sinus node- sinus bradycardia
    • Atheletes
    • Expiration
  • Pathologic slowing of sinus node-
    • Sick sinus syndrome
    • SA block
  • Physiologic or pathologic parasympathetic activation- sinus bradycardia and AV block
    • Increased intracranial or intraocular pressure
    • Vasovagal reflex, carotid reflex
    • Venodilators
    • ]]>     http://www.heartpearls.com/2009/07/ecg-decreased-automaticity-leading-to-bradycardia.html/feed 0     ECG- Ventricular tachyarrhythmias http://www.heartpearls.com/2009/07/ecg-re-entrant-ventricular-tachyarrhythmias.html http://www.heartpearls.com/2009/07/ecg-re-entrant-ventricular-tachyarrhythmias.html#comments Tue, 21 Jul 2009 17:56:01 +0000 Dr Jayachandran Thejus MD http://www.heartpearls.com/?p=446
  • Usual VT is due to reentry and has rate more than 120/mt. AIVR is due to accelerated automaticity and has rate less than 120/mt.
  • Torsades de pointes is due to macro-reentry.

    • Etiologies

    • Idiopathic- RVOT, fascicular
    • CAD- acute MI, past MI
    • Dilated cardiomyopathy, hypertrophic cardiomyopathy
    • ARVC
    • Drugs

    Diagnosis

    • Step 1- search the whole ECG for P waves
      • AV dissociation
        • Especially likely to be seen in leads with low QRS amplitude and in lead v1 (where P waves tend to be prominent)
        • May be absent if there is retrograde atrial activation
        • Entirely specific, but poorly sensitive
      • VA association
        • May be 1:1 or lower.
    • Step 2- search the whole ECG for fusion or capture beats
      • Fusion or capture beats. The latter is premature.
      • Seen only at low rates of less than 160/mt.
    • Step 3- search the precordial leads for RS pattern
      • No RS pattern in any precordial lead
        • Strongly suggests VT. (With RBBB or LBBB, there will be RS in at least one lead.)
      • RS is present in a precordial lead
        • It can still be VT if time from beginning of R to nadir of S is more than 100 msec.
    • Step 4- study QRS morphology in precordial leads
      • RBBB pattern
        • V1-
          • R (can also occur with RVH or PWMI)
          • R with notched downslope producing two rabbit ears, first being taller (Marriott sign, very specific)
          • QR (can also occur with RBBB + MI)
        • V6-
          • QS
          • rS + left axis deviation
      • LBBB pattern
        • V1-
          • R duration 40 msec or more
          • Notched downslope in S
          • Onset of R to nadir of S 60 msec or more
        • V6-
          • QS
          • qR

    Other interesting points

      • RV origin VT occurs in young females while LV origin VT occurs in elderly males with heart disease.
      • TDP is usually nonsustained.
      • Ventricular flutter and fibrillation are due to macro-reentry.
      • Ventricular fibrillation is more difficult to defibrillate than ventricular flutter.
    ]]>     http://www.heartpearls.com/2009/07/ecg-re-entrant-ventricular-tachyarrhythmias.html/feed 0     ECG- Supraventricular tachycardia with aberrancy- features to distinguish from ventricular tachycardia http://www.heartpearls.com/2009/06/what-are-the-main-features-of-supraventricular-tachycardia-with-aberrancy-that-helps-to-distinguish-if-from-ventricular-tachycardia.html http://www.heartpearls.com/2009/06/what-are-the-main-features-of-supraventricular-tachycardia-with-aberrancy-that-helps-to-distinguish-if-from-ventricular-tachycardia.html#comments Tue, 02 Jun 2009 13:53:21 +0000 Dr Jayachandran Thejus MD http://www.heartpearls.com/?p=197
  • RBBB pattern (rsR’ in v1 or qrS in v6).
  • Initial part of the complex is similar to a sinus rhythm complex.
  • Similar complexes seen earlier when patient was in sinus rhythm and then was clearly diagnosed as aberrant conduction.
  • Complex ending a short RR interval after a long RR interval (preceding long RR- short RR sequence; second in a row phenomenon; Ashman phenomenon).
  • The suspected complexes are all having preceding P waves.
  • RBBB and LBBB patterns seen- more likely to be alternating BBB due to varying aberrancy rather than ventricular tachycardias from both ventricles.
    • ]]>     http://www.heartpearls.com/2009/06/what-are-the-main-features-of-supraventricular-tachycardia-with-aberrancy-that-helps-to-distinguish-if-from-ventricular-tachycardia.html/feed 0