Wide-complex Tachycardia

Several algorithms exist for the electrocardigraphic evaluation of regular, wide-complex tachycardias with the objective of distinguishing ventricular tachycardia (VT) from a supraventricular tachycardia (SVT) with aberrant conduction. The algorithm detailed below, developed by Dr. James Niemann, presents an ED-centric approach favoring the diagnosis of the more life-threatening dysrhythmia. This approach recognizes that SVT with aberrancy is rare, particularly in patients with a history of cardiac disease where the likelihood of ventricular tachycardia exceeds 90%. The algorithm requires the use of only the most simple and easily-recalled criteria, and any point of failure along the algorithm lends to the universally-appropriate management as ventricular tachycardia.

Algorithm for the Evaluation of Regular, Wide-Complex Tachycardia

Algorithm for the Evaluation of Wide-Complex Tachycardia

  1. aVR: Is the initial deflection in aVR positive? If yes, then VT.
  2. Concordance: Is there concordance (monophasic with same polarity) in all of the precordial leads? If yes, then VT.
  3. AV Dissociation: Is there evidence of AV dissociation (fusion or capture beats)? If yes, then VT.
  4. Bundle-branch morphology: Is the QRS morphology in V1 and V6 consistent with either LBBB or RBBB? If no, then VT.

References

  1. Neimann J. Wide QRS Complex Tachycardias. Lecture. Harbor-UCLA Department of Emergency Medicine. 2014:1-19.
  2. Vereckei A, Duray G, Szénási G, Altemose GT, Miller JM. New algorithm using only lead aVR for differential diagnosis of wide QRS complex tachycardia. Heart Rhythm. 2008;5(1):89-98. doi:10.1016/j.hrthm.2007.09.020.
  3. Szelényi Z, Duray G, Katona G, et al. Comparison of the “real-life” diagnostic value of two recently published electrocardiogram methods for the differential diagnosis of wide QRS complex tachycardias. Acad Emerg Med. 2013;20(11):1121-1130. doi:10.1111/acem.12247.
  4. Brugada P, Brugada J, Mont L, Smeets J, Andries EW. A new approach to the differential diagnosis of a regular tachycardia with a wide QRS complex. Circulation. 1991;83(5):1649-1659.
  5. Lau EW, Pathamanathan RK, Ng GA, Cooper J, Skehan JD, Griffith MJ. The Bayesian approach improves the electrocardiographic diagnosis of broad complex tachycardia. Pacing Clin Electrophysiol. 2000;23(10 Pt 1):1519-1526.
  6. B Garner J, M Miller J. Wide Complex Tachycardia – Ventricular Tachycardia or Not Ventricular Tachycardia, That Remains the Question. Arrhythm Electrophysiol Rev. 2013;2(1):23-29. doi:10.15420/aer.2013.2.1.23.
  7. Vereckei A. Current algorithms for the diagnosis of wide QRS complex tachycardias. Curr Cardiol Rev. 2014;10(3):262-276.
  8. Garmel GM. Wide Complex Tachycardias: Understanding this Complex Condition: Part 1 – Epidemiology and Electrophysiology. West J Emerg Med. 2008;9(1):28-39.
  9. Garmel GM. Wide Complex Tachycardias: Understanding this Complex Condition Part 2 – Management, Miscellaneous Causes, and Pitfalls. West J Emerg Med. 2008;9(2):97-103.
  10. Griffith MJ, Garratt CJ, Mounsey P, Camm AJ. Ventricular tachycardia as default diagnosis in broad complex tachycardia. The Lancet. 1994;343(8894):386-388.

Sinus Tachycardia

Brief History and Physical:

A young female with a history of schizophrenia presents to the emergency department reporting hallucinations. She had been diagnosed with schizophrenia one year previously and was briefly admitted to a psychiatric hospital. She discontinued her anti-psychotic (risperidone) two months ago, and over the past week she reports increasingly prominent auditory and visual hallucinations.

She denies recent illness, vomiting/diarrhea, changes in urinary habits, new medications, alcohol or illicit substance use. She also denies chest pain, palpitations or shortness of breath.

Vital signs are notable for a heart rate of 148bpm and are otherwise normal (including core temperature). Detailed physical examination is normal except for a rapid, regular heart rate. Mental status examination demonstrated normal level of alertness and orientation, linear and cogent responses and occasional response to internal stimuli during which she appeared anxious.

Initial evaluation and management included a 12-lead ECG which showed sinus tachycardia. Multiple boluses of normal saline were initiated while awaiting laboratory workup.

ECG: Sinus Tachycardia

Presentation ECG demonstrates sinus tachycardia.

Update:

Laboratory studies were reviewed and unremarkable. Normal hemoglobin, normal chemistry panel, negative hCG, and negative toxicology screen. The patient remained persistently tachycardic with a heart rate ranging from 140-160bpm (again sinus tachycardia on 12-lead ECG). An atypical antipsychotic and anxiolytic were administered and additional studies were obtained. Serum TSH, troponin and D-dimer were normal and bedside ultrasound did not identify a pericardial effusion. The patient remained asymptomatic, reporting subjective improvement in anxiety and hallucinations. Psychiatry was consulted and the patient was placed in observation for monitoring of sinus tachycardia. Observation course was uneventful as the patient remained asymptomatic. Transthoracic echocardiography was normal. Psychiatry consultation recommended resumption of home anti-psychotic and outpatient follow-up. Tachycardia had improved but not resolved at the time of discharge (heart rate 109bpm) and the patient was instructed to follow-up with her primary care provider.


Algorithm for the Evaluation of Sinus Tachycardia

Algorithm for the Evaluation of Sinus Tachycardia

Any vital sign derangement is concerning and tachycardia may be associated with unanticipated death after discharge home1. The presence of tachycardia suggests one of several categories of hemodynamic, autonomic, or endocrine/metabolic derangement.

Demand for increased cardiac output

A perceived demand for increased cardiac output will prompt chronotropic (and inotropic) amplification before hypotension develops. Causative etiologies include: volume depletion (from hemorrhage, gastrointestinal or renal losses), distributive processes (such as infection), obstruction (pulmonary embolus, or pericardial effusion with impending tamponade), or tissue hypoxia (anemia or lung disease).

Autonomic nervous system

Autonomic nervous system disturbances induced by stimulant, sympathomimetic or anti-cholinergic use, or withdrawal of certain agents such as ethanol or beta-blockers may be at fault.

Endocrine and other causes

Hyperthyroidism and pheochromocytoma should be considered, and as diagnoses of exclusion: anxiety, pain, or inappropriate sinus tachycardia2.

Evaluation:
Core temperature
CBC
Troponin
D-dimer
Bedside cardiac ultrasound
Urine toxicology screen
Ethanol level
TSH/T4

Algorithm for the Evaluation of Narrow-Complex Tachycardia3,4,5,6

Algorithm for the Evaluation of Narrow-Complex Tachycardia

References:

  1. Sklar DP, Crandall CS, Loeliger E, Edmunds K, Paul I, Helitzer DL. Unanticipated Death After Discharge Home From the Emergency Department. Ann Emerg Med. 2007;49(6):735-745. doi:10.1016/j.annemergmed.2006.11.018.
  2. Olshansky B, Sullivan RM. Inappropriate sinus tachycardia. J Am Coll Cardiol. 2013;61(8):793-801. doi:10.1016/j.jacc.2012.07.074.
  3. Yusuf S, Camm AJ. Deciphering the sinus tachycardias. Clin Cardiol. 2005;28(6):267-276.
  4. Katritsis DG, Josephson ME. Differential diagnosis of regular, narrow-QRS tachycardias. Heart Rhythm. 2015;12(7):1667-1676. doi:10.1016/j.hrthm.2015.03.046.
  5. Bibas L, Levi M, Essebag V. Diagnosis and management of supraventricular tachycardias. CMAJ. 2016;188(17-18):E466-E473. doi:10.1503/cmaj.160079.
  6. Link MS. Clinical practice. Evaluation and initial treatment of supraventricular tachycardia. N Engl J Med. 2012;367(15):1438-1448. doi:10.1056/NEJMcp1111259.

ECG Guide: Pediatrics

ECG Standard

  • Full standard: no adjustment
  • Half-standard: commensurate reduction in amplitude (usually 50%)
  • Mixed: reduction in amplitude of precordial leads

Atrial Abnormalities

Right Atrial Abnormality (P pulmonale)
Peaked P-wave in II (>3mm from 0-6mo or >2.5mm >6mo)
Causes: right atrial volume overload, ASD, Ebstein, Fontan
Left Atrial Abnormality (P mitrale)
Wide, notched P-wave in II or biphasic in V1
Causes: MS, MR

Axis

  • Anatomical dominance of right ventricle until approximately 6mo
  • RAD normal
  • eRAD suggests AV canal defect

T-waves

  • 1st week of life: Upright
  • Adolescent: Inverted
  • Adult: Upright

Ventricular Hypertrophy

Right Ventricular Hypertrophy
R-wave height >98% for age in lead V1
S-wave depth >98% for age in lead V6
T-wave abnormality (ex. upright in childhood)
Causes: pHTN, PS, ToF
Left Ventricular Hypertrophy
R-wave height >98% for age in lead V6
S-wave depth >98% for age in lead V1
Adult-pattern R-wave progression in newborn (no large R-waves and small S-waves in right precordial leads)
Left-axis deviation
Causes: AS, coarctation, VSD, PDA

Examples


Normal Neonatal ECG

  • 2mo old
  • RAD
  • Inverted T-waves (normal)
  • Tall R-waves in V1-V3


Extreme Axis Deviation

  • Neonate with Down syndrome
  • Isoelectric in I, Negative in aVF negative in II  mean QRS vector -87°
  • Extreme RAD suggestive of AV canal defect


LVH:

  • Unrepaired Coarctation
  • Deep S-wave in V1 (>98%)
  • Tall R-wave in V6 (>98%)


RVH:

  • 10 year-old boy with pulmonary Hypertension
  • RAD after expected age for normal RAD
  • Tall R-waves in V1 (>98%)
  • Deep S-wave in V6 (>98%)


STEMI

  • ALCAPA (anomalous origin of the left coronary artery from the pulmonary artery): coronary artery arises anomalously from the pulmonary artery; as pulmonary arterial pressure falls during the first 6 months of infancy, prograde flow through the left coronary artery ceases and may even reverse.
  • HLHS (hypoplastic left heart syndrome): coronary arteries are perfused from a hypoplastic, narrow aorta that is susceptible to flow disruption
  • Orthotopic heart transplant with allograft vasculopathy
  • Kawasaki: coronary artery aneurysm with subsequent thrombosis


Benign early repolarization

  • 14 year-old male
  • Concave ST-segment elevation


Left Atrial Abnormality:

  • 9mo female with mitral insufficiency
  • Broad biphasic P-wave in V1
  • Tall, notched P-wave in II


Prolonged QT interval

  • 18-year-old female
  • Familial long QT syndrome and a history of cardiac arrest


WPW:

  • Delta wave, shortened PR interval

References

  1. O’Connor M, McDaniel N, Brady WJ. The pediatric electrocardiogram. Part I: Age-related interpretation. Am J Emerg Med. 2008;26(2):221-228. doi:10.1016/j.ajem.2007.08.003.
  2. Goodacre S, McLeod K. ABC of clinical electrocardiography: Paediatric electrocardiography. BMJ. 2002;324(7350):1382-1385.
  3. O’Connor M, McDaniel N, Brady WJ. The pediatric electrocardiogram Part II: Dysrhythmias. Am J Emerg Med. 2008;26(3):348-358. doi:10.1016/j.ajem.2007.07.034.
  4. O’Connor M, McDaniel N, Brady WJ. The pediatric electrocardiogram Part III: Congenital heart disease and other cardiac syndromes. Am J Emerg Med. 2008;26(4):497-503. doi:10.1016/j.ajem.2007.08.004.
  5. Schwartz P. Guidelines for the interpretation of the neonatal electrocardiogram. Eur Heart J. 2002;23(17):1329-1344. doi:10.1053/euhj.2002.3274.

ECG Guide: Part II

STEMI

STEMI

  • ST-segment elevation ≥ 1mm in two contiguous leads
  • : ≥ 2mm V2-V3
  • : ≥ 1.5mm V2-V3

Posterior STEMI

  • ST-segment depression V1-V3 Posterior ECG
  • ST-segment elevation ≥ 0.5mm in V7-V9

Sgarbossa Criteria

  • Evaluation for STEMI in LBBB or paced rhythm
  • Normal: ST-segment discordant with QRS

    • QRS associated with ST-segment depression
    • QRS associated with (commensurate) ST-segment elevation
  • Score ≥ 3 98% specific for MI

Elevation

  • Concordant ST-segment elevation ≥ 1mm in any lead (5 points)

Depression

  • Concordant ST-segment depression ≥ 1mm in V1-V3 (3 points)

Discordant Elevation

  • Discordant ST-segment elevation ≥ 5mm in any lead (2 points)

Modified Sgarbossa Criteria

  • ST:S ratio ≥ 0.25 in any lead
  • Presence of any criterion is positive

Other Causes of ST-segment Elevation

Benign Early Repolarization

  • Concave ST-segment elevation
  • Notch at J-point
  • Asymmetric T-waves (steeper descent)

Pericarditis

  • Diffuse ST-segment elevation (except aVR)
  • PR-segment depression
  • Ratio: ST-elevation to T-wave amplitude ≥ 0.25 in V6 suggests pericarditis

LVH Strain

  • ST-segment elevation in V1-V3 in the setting of LVH

LV Aneurysm

  • Q-waves with ST-segment elevation in precordial leads

Ischemia and Prior Infarcts

Wellens: Type A

Wellens: Type B

Q-waves

  • ≥ 40ms duration
  • Depth ≥ 25% of R-wave height

Syncope

ARVD

  • Epsilon wave

Brugada Syndrome: Type 1

  • Type 1: Coved ST-segment elevation

Brugada Syndrome: Type 2

  • Type 2: Saddle-back ST-segment elevation

HCM

  • Deep, narrow Q-waves

Wolff-Parkinson-White

  • Shortened PR-interval
  • Delta-wave

Other

Atrial Abnormalities

  1. Normal
  2. RAA: P-wave amplitude > 2.5mm in inferior leads
  3. LAA: P-wave duration increased (terminal negative portion >0.04s), amplitude of terminal negative component >1mm below isoelectric line in V1

Left Bundle Branch Block


  • QRS duration > 0.12s (3 boxes)
  • Broad or notched R-wave with prolonged upstroke in I, aVL, V5, V6
  • Associated ST-segment depression and T-wave inversion
  • Reciprocal changes in V1, V2 (deep S-wave)
  • Possible LAD

Right Bundle Branch Block


  • QRS duration > 0.12s (3 boxes)
  • RSR’ in V1, V2
  • Reciprocal changes in I, aVL, V5, V6 (deep S-wave)

Axes

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Bradycardia

Brief H&P:

A 38 year-old male with no medical history presents to the emergency department with abdominal pain. He had one episode each of non-bloody emesis followed by watery, non-bloody diarrhea and cited several sick contacts at home with similar symptoms. Vital signs were notable for bradycardia with a heart rate ranging from 38-46bpm though he was normotensive. The examination including abdominal examination was benign. A 12-lead electrocardiogram was obtained which demonstrated sinus bradycardia. The patient was asymptomatic during episodes of bradycardia and his heart rate responded appropriately during activity and on further history reported that he was an endurance athlete and runs multiple marathons each year. He was discharged after symptomatic improvement with anti-emetics.

Bradycardia 1

  • Definition: heart rate <60bpm
  • Sinus rhythm: upright P-wave in I, II, aV; inverted P-wave in aVR

Electrocardiographic Findings 1-4

  • Sinus bradycardia
    • Potentially asymptomatic and present in healthy individuals
  • Sinoatrial node dysfunction (sick sinus syndrome, SSS) 5,6
    • Sinus bradycardia
    • Sinus arrest
    • Tachy-brady syndrome (sinus bradycardia/arrest interspersed with SVT)
  • Atrioventricular block
    • 1st degree: PR prolongation, rarely symptomatic
    • 2nd degree: Intermittent interruption of conduction of atrial impulses to ventricles
      • Type 1: progressive PR prolongation leading to interrupted conduction
      • Type 2: fixed PR interval with interrupted conduction
    • 3rd degree: atrioventricular dissociation
  • Slow atrial fibrillation
    • Irregular RR interval without recognizable P-wave

Epidemiology7

  • Analysis of 277 patients presenting to the emergency department with “compromising” bradycardia.
  • Symptoms
    • Syncope (33%)
    • Dizziness (22%)
    • Angina (17%)
    • Dyspnea/Heart Failure (11%)
  • ECG
    • High-grade AV block (48%)
    • Sinus bradycardia (17%)
    • Sinus arrest (15%)
    • Slow atrial fibrillation (14%)
  • Cause
    • Primary (49%)
    • Drug (21%)
    • Ischemia/Infarction (14%)
    • Pacemaker failure (6%)
    • Intoxication (6%)
    • Electrolyte disorder (4%)

Important Historical Features8,9

  • Fever/travel
  • Chest pain
  • Cold intolerance, weight gain
  • Headache, AMS, trauma
  • Abdominal pain/distension
  • Medication changes

Important Examination Findings8,9

  • Perfusion (temperature, capillary refill)
  • Presence of fistula or hemodialysis catheter
  • Existing device (malfunction)

Workup8,9

  • ECG
  • Continuous telemetry monitoring
  • Labs
    • Potassium
    • Digoxin level
    • TFT
    • Infection titers (RPR, Lyme)
    • Cardiac enzymes

Management8,10

  • Unstable
    • Airway
    • Atropine 0.5mg IV q3-5min (maximum 3mg)
    • Dopamine/epinephrine infusion
    • Temporary pacemaker (transcutaneous, transvenous) with blood-pressure preserving sedation
    • Admission and evaluation for permanent pacemaker placement
  • Stable (outpatient evaluation)
    • Event monitor
    • Stress test (chronotropic incompetence)

Algorithm for the Evaluation and Management of Bradycardia

Algorithm for the evaluation and management of bradycardia

References

  1. Mangrum JM, DiMarco JP. The evaluation and management of bradycardia. N Engl J Med. 2000;342(10):703-709. doi:10.1056/NEJM200003093421006.
  2. Ufberg JW, Clark JS. Bradydysrhythmias and atrioventricular conduction blocks. Emergency Medicine Clinics of NA. 2006;24(1):1–9–v. doi:10.1016/j.emc.2005.08.006.
  3. Hayden GE, Brady WJ, Pollack M, Harrigan RA. Electrocardiographic manifestations: diagnosis of atrioventricular block in the Emergency Department. J Emerg Med. 2004;26(1):95-106. doi:10.1016/j.jemermed.2003.10.001.
  4. Da Costa D, Brady WJ, Edhouse J. Bradycardias and atrioventricular conduction block. BMJ. 2002;324(7336):535-538.
  5. Semelka M, Gera J, Usman S. Sick sinus syndrome: a review. Am Fam Physician. 2013;87(10):691-696.
  6. Ewy GA. Sick sinus syndrome: synopsis. J Am Coll Cardiol. 2014;64(6):539-540. doi:10.1016/j.jacc.2014.05.029.
  7. Sodeck GH, Domanovits H, Meron G, et al. Compromising bradycardia: management in the emergency department. Resuscitation. 2007;73(1):96-102. doi:10.1016/j.resuscitation.2006.08.006.
  8. Deal N. Evaluation and management of bradydysrhythmias in the emergency department. Emergency Medicine Practice. 2013;15(9):1–15–quiz15–6.
  9. Demla V, Rohra A. Emergency Department Evaluation and Management of Bradyarrhythmia. Hospital Medicine Clinics. 2015;4(4):526-539. doi:https://doi.org/10.1016/j.ehmc.2015.06.009.
  10. Brady WJ, Harrigan RA. Evaluation and management of bradyarrhythmias in the emergency department. Emergency Medicine Clinics of NA. 1998;16(2):361-388.

Wellens Syndrome

Case Presentation

49M with a history of hypertension who presented to his primary physician for routine follow-up and was referred to the ED for an abnormal ECG. He denied chest pain, shortness of breath, or any limitation to baseline exercise tolerance. His vital signs were notable for systolic hypertension and his examination was unremarkable. A chest x-ray showed no acute cardiopulmonary findings. His initial ECG demonstrated a biphasic T-wave in V2 and deep, symmetric T-wave inversions in V3-V6. His initial serum troponin was markedly elevated at 3.499. He was admitted and urgent coronary angiography revealed proximal LAD stenosis (70%), mid-LAD stenosis (85%) and 1st right posterolateral stenosis (85%) which were stented. He was discharged on post-procedure day one and has remained asymptomatic at outpatient follow-up.

Presentation ECG
Presentation ECG

Presentation ECG

Biphasic T-wave in V2, deep and symmetric T-wave inversions in V3-V4

Post-Catheterization ECG
Post-Catheterization ECG

Post-Catheterization ECG

Resolution of biphasic T-wave and T-wave inversions

History1

Initially described in 1982 where a subset of patients who did poorly with medical management of “impending myocardial infarction” (essentialy unstable angina) were found to have characteristic ECG changes. These patients were noted to be at increased risk for extensive anterior wall myocardial infarctions due to proximal LAD stenosis.

Wellens ECG patterns

Criteria2,3

  1. History of chest pain
  2. Normal or slightly-elevated cardiac enzymes
  3. No precordial Q-waves
  4. Isoelectric or <1mm ST-segment elevation
  5. Pattern present in pain-free state
  6. Type A (25%): Biphasic T-wave in V2/V3
  7. Type B (75%): Deep, symmetrically inverted T-waves in V2/V3

Clinical Significance3

Wellens Syndrome (or LAD coronary T-wave syndrome) represents a “pre-infarction” stage of coronary artery disease manifested by critical LAD stenosis. The natural history includes progression to extensive anterior wall myocardial infarction, often associated with severe left ventricular systolic dysfunction, cardiogenic shock and death. These changes may be mistaken for “non-specific” T-wave changes (which in the presence of a non-concerning history and typically non-elevated cardiac markers) may lead providers to inappropriate dispositions such a stress testing which is contraindicated. Recognition of this pattern and its appropriate management (urgent coronary angiography) is critical.

Case Summary

The case presented above is atypical. The patient had no history of chest pain and cardiac enzymes were significantly elevated – two features which are uncommon in Wellens Syndrome. However, the patient’s elevated cardiac biomarkers led to admission and angiography with identification of the characteristic proximal LAD stenosis (and other disease).

References:

  1. de Zwaan C, Bär FW, Wellens HJ. Characteristic electrocardiographic pattern indicating a critical stenosis high in left anterior descending coronary artery in patients admitted because of impending myocardial infarction. Am Heart J. 1982;103(4 Pt 2):730-736.
  2. Tandy TK, Bottomy DP, Lewis JG. Wellens’ syndrome. YMEM. 1999;33(3):347-351.
  3. Rhinehardt J, Brady WJ, Perron AD, Mattu A. Electrocardiographic manifestations of Wellens’ syndrome. American Journal of Emergency Medicine. 2002;20(7):638-643. doi:10.1053/ajem.2002.34800.
  4. Mead N, O Keefe K. Wellen′s Syndrome: An Ominous EKG pattern. J Emerg Trauma Shock. 2009;2(3):206– doi:10.4103/0974-2700.55347.
  5. Kannan L, Figueredo VM. Images in clinical medicine. Wellens’ syndrome. N Engl J Med. 2015;372(1):66. doi:10.1056/NEJMicm1400946.

Nonsustained Ventricular Tachycardia

Case 1

64M with a history of HFrEF (LVEF 20-25%), CAD, AICD (unknown indication), COPD, CKD III presenting with gradual onset shortness of breath, progressive bilateral lower extremity edema.
Examination consistent with severe acute decompensated heart failure presumed secondary to left ventricular dysfunction.
Telemetry monitoring with multiple episodes of nonsustained ventricular tachycardia.

In the ED, the patient developed worsening respiratory failure despite initiation of therapy, requiring endotracheal intubation. Continuous cardiac monitoring revealed persistent salvos of NSVT, progressing to slow ventricular tachycardia without device intervention.
Device interrogation revealed multiple events, 3 shocks, several ATP’s over the recorded period.

Evaluation and Management:

  • NSVT with known (severe) ischemic heart disease
  • For repetitive monomorphic ventricular tachycardia: amiodarone, beta-blockade (if tolerated), procainamide (IIA, C)1

ECG’s

ECG 1
ECG 1

ECG 1

Non-specific IVCD, LAA, VPC

ECG 2
ECG 2

ECG 2

VT initiated by fusion complex

Case 2

31F with autoimmune polyglandular syndrome (adrenal, thyroid and endocrine pancreatic insufficiency), presenting with fever and cough.
Evaluation consistent with sepsis presumed secondary to pulmonary source.
Telemetry monitoring initially with ventricular bigeminy, then nonsustained ventricular tachycardia.

In the ED, the patient developed pulseless ventricular tachycardia – apparently polymorphic. Chest compressions and epinephrine produced return of spontaneous circulation with recovery to baseline neurologic function.
ECG revealed prolonged QTc and chemistry panel notable for critical hypokalemia/hypomagnesemia.

Evaluation and Management:

  • NSVT progressing to VT
  • Initially attributed to electrolyte disturbances. However, serial ECG’s continued to show prolonged QTc (possibly acquired, home medications included metoclopramide and erythromycin). Early echocardiography demonstrated global hypokinesis with EF 30-35% attributed to severe sepsis and recurrent defibrillation. Cardiac CT after resolution of acute illness showed persistently depressed ejection fraction without coronary atherosclerosis. The presence of NICM associated with malignant dysrhythmias warranted ICD placement.
  • Cardioversion for hemodynamic compromise (I, B), B-blockade (I, B), amiodarone if no LQTS (I, C), urgent angiography if ischemia not excluded (I, C)1
  • Correction of electrolyte abnormalities (specifically hypokalemia) may decrease progression to VF.2

ECG’s

ECG 1
ECG 1

ECG 1

Ventricular bigeminy

ECG 2
ECG 2

ECG 2

Long-QT

VT on Telemetry
VT on Telemetry

VT on Telemetry

Non-sustained ventricular tachycardia noted on telemetry monitoring

Definition3,4

  • > 3-5 consecutive beats originating below the AV node
  • Rate > 100bpm
  • Duration <30s

Epidemiology3,5

  • Occurs in 0-4% of ambulatory patients
  • Increased frequency in males and with increasing age
  • In some patients, NSVT is associated with an increased risk of sustained tachyarrhythmias and sudden cardiac death. In others it is of little prognostic significance.6,7,8

Evaluation

In all patients:
History: including arrhythmogenic medications/substances, pertinent family history
Physical examination
ECG/CXR
TTE
In selected patients:
Exercise testing
Advanced imaging (CT/C-MR)
Electrophysiologic studies
Genetic testing

NSVT in the absence of structural heart disease

NSVT in Idiopathic Ventricular Tachycardia

Ventricular outflow arrhythmias:
RVOT: 70-80%, LBBB pattern
LVOT: 20-30%, RBBB pattern
Mechanism:
Adrenergically mediated
Occur during exercise, resolve as heart-rate increases, recur during recovery
Management:
Exclude arrhythmogenic right ventricular cardiomyopathy (imaging, myocardial biopsy)
If symptomatic, beta-blockade, ± IC anti-arrhythmic, CCB (verapamil) for ILVT
Prognosis:
Good, rare tachycardia-induced cardiomyopathy, rare SCD

NSVT in Polymorphic Ventricular Tachycardia

Mechanism
LQTS (acquired or inherited)
Familial catecholaminergic polymorphic VT
Management
Symptomatic (ex. syncope, cardiac arrest): ICD
Asymptomatic QTc > 550ms: consider ICD
Prognosis
Increased risk SCD

Arrhythmogenic Right Ventricular Cardiomyopathy

Mechanism
Fibrosis, fibro-fatty replacement of myocardium in RVIT/RVOT/RV apex
May occur with only subtle structural abnormalities of the right ventricle
LBBB morphology
Management
Anti-arrhythmics of limited utility
Catheter ablation, ICD backup
Prognosis
Increased risk SCD

NSVT with apparent structural heart disease1

Hypertension and LVH

Mechanism
Stretch-induced abnormal automaticity
Fibrotic tissue
Presence of NSVT correlates with degree of hypertrophy and subendocardial fibrosis
Management
Evaluation for ischemic heart disease
Aggressive medical management of hypertension (including beta-blockade)
Prognosis
Unclear

Valvular Disease

Mechanism
High incidence in AS, severe MR (25%)
Mechanical stress from dysfunctional valvular apparatus
Management
Beta-blockade if symptomatic
Prognosis
No evidence that NSVT is an independent predictor of SCD.

Ischemic Heart Disease9-14

Mechanism
Monomorphic VT associated with re-entry at the borders of ventricular scars
Ischemia induces polymorphic NSVT/VF
Management
Revascularization, beta-blockade, statin, ACE/ARB
MADIT I, MUSTT: ICD for ICM LVEF <40%, NSVT, EPS inducible VT
MADIT II, SCD-HeFT: ICD for moderate-to-severe LV dysfunction irrespective of NSVT or EPS findings
Prognosis
NSTEMI with NSVT >48h after admission 2x risk SCD (MERLIN-TIMI 36)
STEMI with NSVT common, not as predictive of ACM or SCD as LVEF (CARISMA)
NSVT <24h after admission for NSTEMI/STEMI not of prognostic significance.

Hypertrophic Cardiomyopathy

Mechanism
Genetic myocardial disease
Myocyte disarray, fibrosis, ischemia result in arrhythmogenic substrate
Management
Restriction of physical activity
ICD (NSVT, LV thickness, FH SCD, syncope, abnormal BP response to exercise)
Beta-blockade, anti-arrhythmic for symptoms
Prognosis
Increased risk SCD (1% annual)

Other Conditions

  • Non-ischemic dilated cardiomyopathy
  • Giant-cell myocarditis
  • Repaired TOF
  • Amyloidosis
  • Sarcoidosis
  • Chagas cardiomyopathy

Algorithm for the Evaluation of NSVT1

Algorithm for the Evaluation of Nonsustained Ventricular Tachycardia

References

  1. Zipes DP, Camm AJ, Borggrefe M, et al. ACC/AHA/ESC 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death–executive summary: A report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for Management of Patients with Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death) Developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society. Eur Heart J. 2006;27(17):2099–2140. doi:10.1093/eurheartj/ehl199.
  2. Higham PD, Adams PC, Murray A, Campbell RW. Plasma potassium, serum magnesium and ventricular fibrillation: a prospective study. Q J Med. 1993;86(9):609–617.
  3. Katritsis DG, Zareba W, Camm AJ. Nonsustained ventricular tachycardia. J Am Coll Cardiol. 2012;60(20):1993–2004. doi:10.1016/j.jacc.2011.12.063.
  4. Katritsis DG, Camm AJ. Nonsustained ventricular tachycardia: where do we stand? Eur Heart J. 2004;25(13):1093–1099. doi:10.1016/j.ehj.2004.03.022.
  5. Wellens HJ. Electrophysiology: Ventricular tachycardia: diagnosis of broad QRS complex tachycardia. Heart. 2001;86(5):579–585.
  6. Buxton AE, Lee KL, Fisher JD, Josephson ME, Prystowsky EN, Hafley G. A randomized study of the prevention of sudden death in patients with coronary artery disease. Multicenter Unsustained Tachycardia Trial Investigators. N Engl J Med. 1999;341(25):1882–1890. doi:10.1056/NEJM199912163412503.
  7. Jouven X, Zureik M, Desnos M, Courbon D, Ducimetière P. Long-term outcome in asymptomatic men with exercise-induced premature ventricular depolarizations. N Engl J Med. 2000;343(12):826–833. doi:10.1056/NEJM200009213431201.
  8. Udall JA, Ellestad MH. Predictive implications of ventricular premature contractions associated with treadmill stress testing. Circulation. 1977;56(6):985–989.
  9. Preliminary report: effect of encainide and flecainide on mortality in a randomized trial of arrhythmia suppression after myocardial infarction. The Cardiac Arrhythmia Suppression Trial (CAST) Investigators. N Engl J Med. 1989;321(6):406–412. doi:10.1056/NEJM198908103210629.
  10. Goldstein S. Propranolol therapy in patients with acute myocardial infarction: the Beta-Blocker Heart Attack Trial. Circulation. 1983;67(6 Pt 2):I53–7.
  11. Moss AJ. MADIT-I and MADIT-II. J Cardiovasc Electrophysiol. 2003;14(9 Suppl):S96–8.
  12. Moss AJ, Hall WJ, Cannom DS, et al. Improved survival with an implanted defibrillator in patients with coronary disease at high risk for ventricular arrhythmia. Multicenter Automatic Defibrillator Implantation Trial Investigators. N Engl J Med. 1996;335(26):1933–1940. doi:10.1056/NEJM199612263352601.
  13. Buxton AE, Lee KL, Fisher JD, Josephson ME, Prystowsky EN, Hafley G. A randomized study of the prevention of sudden death in patients with coronary artery disease. Multicenter Unsustained Tachycardia Trial Investigators. N Engl J Med. 1999;341(25):1882–1890. doi:10.1056/NEJM199912163412503.
  14. Bardy GH, Lee KL, Mark DB, et al. Amiodarone or an implantable cardioverter-defibrillator for congestive heart failure. N Engl J Med. 2005;352(3):225–237. doi:10.1056/NEJMoa043399.
  15. WikEM: Nonsustained Ventricular Tachycardia

Low Voltage ECG

Definition

  • QRS in limb leads <5mm
  • QRS in precordial leads <10mm

General Causes

  • Fluid, fat or air attenuating signal
  • Myocardial infiltration
  • Loss of viable myocardium

Example

Low Voltage ECG
Low Voltage ECG

Low Voltage ECG

ECG of patient with pericardial effusion

Baseline ECG
Baseline ECG

Baseline ECG

Old ECG from same patient

Differential Diagnosis of Low Voltage ECG

Differential Diagnosis of Low Voltage ECG

References

  1. Madias JE. Low QRS voltage and its causes. J Electrocardiol. 2008;41(6):498–500. doi:10.1016/j.jelectrocard.2008.06.021.
  2. WikEM: Low ECG voltage

ECG Guide

The format of this article is atypical for the structure and concept of the website – but it’s always been about learning. Here is a simplified guide to ECG interpretation with a focus on the aspects I find more challenging to understand or recall.

Grid and Leads

The ECG grid
Limb leads
Precordial Leads

Axis

ECG axes

Atrial Enlargement

Atrial enlargement

Normal:
First portion of deflection is RA, second is LA
Right Atrial Enlargement:
P-wave amplitude > 2.5mm in inferior leads
Normal duration P-wave
Left Atrial Enlargement:
P-wave duration increased (terminal negative portion >0.04s)
Amplitude of terminal negative component >1mm below isoelectric line in V1

Ventricular Hypertrophy

Right Ventricular Hypertrophy:
Right axis deviation
Abnormal R-wave progression

  • Increased R-wave amplitude in leads overlying the right ventricle (V1)
  • Increased S-wave amplitude in leads overlying the left ventricle (V6)
Criteria

  • V1: R>S
  • V6: S>R
Left Ventricular Hypertrophy:
Left axis deviation
Increased R-wave amplitude in leads overlying the LV (I, aVL, V5, V6)
Increased S-wave amplitude in leads overlying the RV (V1)
Criteria:

  • Precordial Leads
    • R-wave in V5/V6 + S-wave in V1/V2 > 35mm
    • R-wave in V5 > 26mm
    • R-wave in V6 > 20mm
  • Limb Leads
    • R-wave in aVL > 11mm
    • R-wave in aVF > 20mm
  • Combined
    • R-wave in aVL + S-wave in V3 > 20mm (F), 28mm (M)

Secondary Repolarization Abnormalities

Secondary repolarization abnormality

  • Downsloping ST-segment depression
  • Asymmetric T-wave inversion

Bundle Branch Blocks

Left Bundle Branch Block

Left bundle branch block

  • QRS duration > 0.12s (3 boxes)
  • Broad or notched R-wave with prolonged upstroke in I, aVL, V5, V6
  • Associated ST-segment depression and T-wave inversion
  • Reciprocal changes in V1, V2 (deep S-wave)
  • Possible LAD

Right Bundle Branch Block

Right bundle branch block

  • QRS duration > 0.12s (3 boxes)
  • RSR’ in V1, V2
  • Reciprocal changes in I, aVL, V5, V6 (deep S-wave)

Hemiblocks

His-Purkinje system and hemiblocks (anterior fascicular block, posterior fascicular block)

Other Blocks

  • Non-specific intraventricular conduction delay: QRS >0.10s without BBB
  • Incomplete BBB: LBBB/RBBB pattern with non-prolonged QRS
  • Bifascicular block: RBBB + LAFB/LPFB (by axis deviation)

Ischemia and Infarction

ECG changes associated with ischemia and infarction

  1. Hyperacute T-waves
  2. T-wave inversion: Symmetric, compared to TWI associated with repolarization abnormalities
  3. ST-elevation: Unlike J-point elevation, ST-segment merges with T-wave
  4. Q-waves
    1. Duration > 0.04s
    2. Amplitude > 1/3 R-wave
    3. Normal in aVR

Coronary Artery Territories

Coronary artery territories

Distribution Coronary Artery Leads Reciprocal Changes
1. Inferior RCA, PDA II, III, aVF Anterior, Lateral
2. Lateral LCx I, aVL, V5, V6 Inferior
3. Anterior LAD V1-V6 Inferior
4. Posterior RCA Posterior Anterior (esp. V1)

External Links