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“…cardiac syncope can be a harbinger of sudden death.”

“…cardiac syncope can be a harbinger of sudden death.”

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Syncope Due to Structural Cardiovascular Disease:

Principle Mechanisms





Acute MI/Ischemia







• 2° neural reflex bradycardia –

Vasodilatation, arrhythmias,

low output (rare)







Hypertrophic cardiomyopathy



• Limited output during exertion



(increased obstruction, greater

demand), arrhythmias, neural

reflex







Acute aortic dissection



• Neural reflex mechanism,

pericardial tamponade



Brignole M, et al. Europace. 2004;6:467-537.



Pulmonary embolus/

pulmonary hypertension



• Neural reflex, inadequate

flow with exertion







Valvular abnormalities



• Aortic stenosis – Limited output,



neural reflex dilation in periphery



• Mitral stenosis, atrial myxoma –

Obstruction to adequate flow



Syncope Due to Cardiac Arrhythmias





Bradyarrhythmias



• Sinus arrest, exit block

• High grade or acute complete AV block

• Can be accompanied by vasodilatation (VVS, CSS)





Tachyarrhythmias



• Atrial fibrillation/flutter with rapid ventricular rate

(eg, pre-excitation syndrome)



• Paroxysmal SVT or VT

• Torsade de pointes



Brignole M, et al. Europace. 2004;6:467-537.



ILR Recordings



CASE: 83 year-old woman with

syncope due to bradycardia:

Pacemaker implanted.



Reveal ® ILR recordings; Medtronic data on file.



CASE: 28 year-old man presents

to ER multiple times after falls

resulting in trauma. VT: Ablated

and medicated.



Long QT Syndromes





Mechanism



• Abnormalities of sodium and/or potassium channels





(LQTC1&2=K+, LQTC3=Na+)



• Susceptibility to polymorphic VT (Torsade de pointes)





Prevalence



• Drug-induced forms – Common

• Genetic forms – Relatively rare, but increasingly being recognized

• “Concealed” forms:





May be common







Provide basis for drug-induced torsade



Schwartz P, Priori S. In: Zipes D and Jalife J, eds. Cardiac Electrophysiology. Saunders;2004:651-659.



Syncope: Torsade de Pointes



From the files of DG Benditt, MD. U of M Cardiac Arrhythmia Center



Drug-Induced QT Prolongation

(List is continuously being updated)





Antiarrhythmics







• Erythromycin, Pentamidine,



• Class IA ...Quinidine,



Fluconazole, Ciprofloxacin and

its relatives



Procainamide, Disopyramide



• Class III…Sotalol, Ibutilide,



Dofetilide, Amiodarone, NAPA*











Antianginal Agents



Nonsedating antihistamines



• Terfenadine*, Astemizole



• Bepridil*





Antibiotics







Psychoactive Agents



• Phenothiazines, Amitriptyline,



Others



• Cisapride*, Droperidol,

Haloperidol



Imipramine, Ziprasidone



www.arizonacert.org

*Removed from U.S. Market

Brignole M, et al. Europace, 2004;6:467-537.



Treatment of Long QT





Suspicion and recognition are critical







Emergency treatment















Intravenous magnesium

Pacing to overcome bradycardia or pauses

Isoproterenol to increase heart rate and shorten repolarization

ICD if prior SCA or strong family history

If drug induced:





Reverse bradycardia







Withdraw drug







Avoid ALL long-QT provoking agents



• If genetic:









Avoid ALL long-QT provoking agents



For more information visit www.longqt.org



Schwartz P, Priori S. In: Zipes D and Jalife J, eds. Cardiac Electrophysiology. Saunders;2004:651-659.



Treatment of Syncope

Due to Bradyarrhythmia





Class I indication for

pacing using dual

chamber system

wherever possible



0.4 nV

0.2



08:23:21



0.0

-0.2

-0.4

:21



:22



:23



:24



:25



:26



:27



:28



:29



0.4

0.2







Ventricular pacing in

atrial fibrillation with

slow ventricular

response



8:23:29



0.0

-0.2

-0.4

:29



:30



:31



:32



:33



:34



:35



:36



:37



0.4

0.2



08:23:37



0.0

-0.2

-0.4

:37



ACC/AHA/NASPE 2002 Guideline Update. Circ. 2002;106:2145-2161.



:38



:39



:40



:41



:42



:43



:44



:45



Treatment of Syncope

Due to Tachyarrhythmia





Atrial tachyarrhythmias



• AVRT due to accessory pathway – Ablate pathway

• AVNRT – Ablate AV nodal slow pathway

• Atrial fib – Pacing, linear/focal ablation for paroxysmal AF

• Atrial flutter – Ablate the IVC-TV isthmus of the re-entrant circuit

for ‘typical’ flutter







Ventricular tachyarrhythmias



• Ventricular tachycardia – ICD or ablation where appropriate

• Torsade de pointes – Withdraw offending drug or implant ICD

(long QT/Brugada/short QT)







Drug therapy may be an alternative in many cases



Brignole M, et al. Europace. 2004;6:467-537.



Neurally-Mediated Reflex Syncope





Vasovagal Syncope (VVS)







Carotid Sinus Syndrome (CSS)







Situational syncope



• Micturition

• Defecation

• Cough

• Deglutition

• Sneezing

• Blood drawing

• Trumpet playing

Brignole M, et al. Europace, 2004;6:467-537.



VVS

Clinical Pathophysiology





Neurally-mediated physiologic reflex mechanism with

two components:

1. Cardioinhibitory (↓ HR)

2. Vasodepressor (↓ BP) despite heart beats, no significant

BP generated







Both components are usually present



1



2



Wieling W, et al. In: Benditt D, et al. The Evaluation and Treatment of Syncope. Futura. 2003;11-22.



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