LEFT BUNDLE BRANCH BLOCK TYPICAL VS ATYPICAL ECG PATTERN. Monophasic, broad notched or slurred R wave, recorded slowly

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1 LEFT BUNDLE BRANCH BLOCK TYPICAL VS ATYPICAL ECG PATTERN SUBJACENT SUBSTRATE RELATIVE FREQUENCY TYPICAL LBBB Variable. 95% OF ALL CASES LBBB. QRS AXIS Between - 30 and + 60 degree, or with extreme deviation to the left: beyond 30 degree. QRS PATTERN IN LEFT LEADS I, avl, V5, V6 Monophasic, broad notched or slurred R wave, recorded slowly ATYPICAL LBBB Predominance of severe dilated cardiomyopathy. <1% OF ALL CASES LBBB. Beyond +90 degree RS, rs or W pattern QRS HP VCG LOOP avr QRS PATTERN QRS loop on left posterior quadrant, CW rotation, afferent limb located to left efferent limb. QRS complex of the QS type almost constant in avr. Sometimes QRS loop on right posterior quadrant, CW rotation, afferent limb located to left efferent limb. If QRS axis is located to right +120 degree positive wave is register. PROGNOSIS Variable Bad. Ominous SINO-VENTRICULAR RHYTHYM DEFINITION: It is ECG conditions observed in severe hyperkalemia( 8.4 meq/l) characterized by absence of P wave on ECG. The stimulus originates in the SA node, it is conducted to the AV node through internodal bundles( preferential) and reaches the junction without depolarizing the atrial muscle (P wave is not recorded). Concomitantly, is observed diffuse QRS complexes widening, similar to left or right bundle branch block, associated to anterior or posterior fascicular block by extreme shift of SAQRS in the FP to left or right. This QRS complex widening is differentiated of genuine branch blocks, because in them, the delay is final or middle, while in hyperpotasemia is always global or diffuse delay. RBBB: final conduction delay. LBBB: middle-final delay. Hyperpotasemia: global delay. In the late phase, a possible convergence of the QRS complex with the T wave is described, outlining a smooth diphasic wave or sine curve associated to concomitant QT interval prolongation.

2 ST segment depression or elevation may be observed, known as dialyzable injury current that may possibly resemble electrocardiographic Brugada-like pattern. Rare cases are described, which resemble acute antero-septal infarction by absence of R wave from V1 to V4 associated to ST segment elevation of the subepicardial injury current. Typical example of ECG of patient with extremely high level of serum potassium. Clinical diagnosis: chronic renal insufficiency in dialysis. The patient delayed 72 hours the dialysis session. Hyperpotasemia of 9 meq/l. ECG diagnosis: absence of P wave, sinoventricular rhythm, 57 bpm, morphology of bizarre intraventricular severe disorder (QRSd: 240 ms) that is similar to complete left bundle branch block. T waves with polarity matching with QRS from V3 to V6. Convergence of QRS with T wave that outlines smooth diphasic wave or sine curve.

3 Clinical diagnosis: chronic renal insufficiency in dialysis. The patient delayed 72 hours the dialysis session. Hyperpotasemia of 9 meq/l. ECG diagnosis: absence of P wave, synoventricular rhythm, 57 bpm, morphology of bizarre intraventricular severe disorder (QRSd: 240 ms) that is similar to complete left bundle branch block. T waves with polarity matching with QRS from V3 to V6. Convergence of QRS with T wave that outlines smooth diphasic wave or sine curve. The so-called Propofol Infusion Syndrome or PRIS is characterized by the association of: Hyperpotasemia Heart failure Sudden cardiac death Unexplained Metabolic lactic acidosis Rhabdomyolysis Lipemia Cardiovascular collapse and Brugada-like electrocardiographic pattern or Brugada ECG phenocopy changes following high-dose propofol infusion over prolonged periods of time. This entity is observed when the drug is administered in high doses, in rates > 5 mg/kg/hr during a period > 2 days. The average of the used dose for PRIS appearance was 6.5 mg/kg/hr. Propofol (DiprivanR) is an endovenous sedative-hypnotic anesthetic agent with short duration of action, used to induce anesthesia in children older than 3 years

4 old, and to maintain general anesthesia in adults and > 2 months. The drug is used as general anesthetic agent and to reduce encephalic injury pressure. This anesthetic drug may cause a rare condition named Propofol Infusion Syndrome, characterized by unexplained lactic acidosis, lipemia, rhabdomyolysis, cardiovascular collapse and Brugada-like electrocardiographic pattern or Brugada ECG phenocopy changes following high-dose propofol infusion over prolonged periods of time. Several articles have contributed to our understanding of the cause of the syndrome, and the growing number of case reports has made it possible to identify several risk factors. Uncertainty remains as to whether a genetic susceptibility exists. The favorable recovery profile associated with propofol offers advantages over traditional anesthetics in clinical situations in which rapid recovery is important. Propofol is a safe anesthetic agent, but Propofol Infusion Syndrome is a rare lethal complication.

5 TYPICAL ELECTROCARDIOGRAM OF HYPERPOTASEMIA ASSOCIATED TO BRUGADA-LIKE PATTERN SECONDARY TO PROPOFOL INFUSION SYNDROME Clinical diagnosis: terminal renal insufficiency. Hyperkalemia: 8.7 meq/l. This sign is known as dialyzable injury current. ECG diagnosis: very likely, sinus rhythm with non-visible P waves, HR: 54 bpm, QRSd: 160 ms, ST segment elevation from V1 to V3 and DI, avl and avr. V1 to V3 display upwardly convex ST segment pattern, similar to Brugada syndrome, which some authors call Acquired Brugada Pattern ; typical T waves in tent, pointed, and with a narrow base. All the best Andrés.