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.

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