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Brain & Heart Epinephrine for CPVT

successfully ceased by 200J electrical shock, returning to The most interesting finding was that our case required
sinus rhythm. Since the diagnosis of CPVT was established, an unconventional dose of epinephrine before being
β-blocker (metoprolol 23.75 mg/day) was prescribed precisely diagnosed. The upper limit recommended by the
before discharge. Mayo Clinic protocol was 0.20 μg/kg/min, which showed
no arrhythmia but only increased heart rate. Taking some
3. Discussion insensitive individuals into consideration, we decided

CPVT is a potentially life-threatening inherited disease to use ~0.80 μg/kg/min dose. Ventricular fibrillation
characterized by polymorphic ventricular arrhythmia following tachycardia was induced and subsequently
in the setting of high adrenergic tone . Early diagnosis stopped by giving an electrical shock. Although the Mayo
[1]
of CPVT is of great importance since CPVT plays an Clinic protocol was generally regarded as the standard
important role in sudden cardiac death, especially in the method for diagnosis of CPVT, our patient was not
young. The patients usually develop syncope or sudden diagnosed until an unconventional dose was selected and
death at an early age in the absence of structural heart administered. Other centers reported some CPVT patients
disease. In some cases, the resting ECG is normal, and the with negative results during regular dose epinephrine
QT interval can be borderline . Nevertheless, arrhythmia infusion who were eventually diagnosed by RyR2 genetic
[6]
[3]
can be reproducibly induced by stress tests as well as test . It may be due to individual variations in the
epinephrine infusion. The mechanism of CPVT is related sensitivities to catecholamine. Some insensitive patients
may not respond well to a regular dose of epinephrine
to two gene mutations, the cardiac ryanodine receptor (≤0.20 μg/kg/min). Therefore, we believe that our special
gene (RyR2) and calsequestrin 2 gene (CASQ2) [7,8] . These experience will provide some useful information for the
mutations lead to an elevation in intracellular calcium diagnostic test of CPVT.
concentration, causing potentially life-threatening
ventricular arrhythmias. Current recommendations 4. Conclusion
for therapy of CPVT include β-blocker, implantable
cardioverter defibrillator, and verapamil . The efficacy of An unconventional dose of epinephrine is needed for a
[9]
flecainide has also been confirmed in some studies and diagnostic test of CPVT for some insensitive individuals.
could be combined with β-blocker to be administered to Acknowledgments
highly symptomatic CPVT patients .
[10]
None.
β-blockers are the key drugs for the treatment
of catecholamine-sensitive polymorphic ventricular Funding
tachycardia, which belong to Class II antiarrhythmic
drugs, and mainly inhibit adrenaline-dependent Project supported by Guangzhou Committee of Science
triggering by reducing heart rate and directly antagonizing and Technology, China(Grant No. 202103000010) and
catecholamines at the cellular level. It is currently the drug clinical frontier new technology of the First Affiliated
of choice for the treatment of CPVT. It is recommended Hospital of Jinan University (Grant No.JNU1AF-CFTP-
to use non-selective dosage forms without endogenous 2022-a01218).
sympathomimetic activity and generally choose nadolol, Conflict of interest
propranolol, metoprolol, and others. Studies have
confirmed that β-blockers are effective for most CPVT The authors declare no conflicts of interest.
patients, and the incidence of malignant cardiac events in
CPVT decreased significantly after treatment. Author contributions
Studies have shown that treatment dose is an important Conceptualization: Jun Guo
factor affecting prognosis. Patients with CPVT need long- Investigation: Xianghui Chen
term and sufficient use of β-blockers, and whether exercise Supervision: Jun Guo
tests induce arrhythmias is to be used as a tool to evaluate Writing – original draft: Xianghui Chen
the efficacy of β-blockers and subsequently adjust the Writing – review & editing: Yongji Lai
drug doses. However, severe bradycardia, atrioventricular Ethics approval and consent to participate
block, and increased airway resistance may occur when
large doses of β-blockers are used. Therefore, based on our Not Applicable.
observations during the clinical diagnosis and treatment
of this patient, we selected the maximum tolerated dose of Consent for publication
23.75 mg/day. The patient consented the data for publication.

Volume 1 Issue 1 (2023) 3 https://doi.org/10.36922/bh.0325