Monitoring
We compared the use of a mandibular nerve block with 2 cartridges (3.6
mL) of 2% lidocaine (72 000 μg of lidocaine) without a vasoconstrictor
and 2 cartridges of 2% lidocaine with 1:100 000 epinephrine (36 μg of
epinephrine) in all patients resulting in 2 conditions, verifying the
occurrence of life-threatening arrhythmias (hemodynamically unstable
arrhythmias, sustained ventricular tachycardia, or appropriate device
shocks) in selected patients with CChs and ICD.
All patients were submitted to two sessions of restorative dental
treatment with a washout period of 7 days (crossover trial) and the same
patients were further used as their own controls.
The procedure was blinded to the patient and the dentist performing to
the presence or absence of epinephrine, then the carpule syringe was
covered with sterile aluminum foil by one of our research team members.
Our research team developed a randomization program in Excel (Microsoft
Office) accomplished by the randomization of the anesthetic solution
application.
The cardiac electrical activity was registred and analyzed during the
two sessions in all patients for 28 hours by a Holter monitor (SEER
Light Extend; GE Healthcare Brazil) with 3-channels (V1, V3, and V5
equivalent leads), starting 1 hour before the procedure. The occurrence
and frequency of ventricular and supraventricular arrhythmias,
identified on a minute-by-minute basis over the 28-hour study period
(basal period, anesthesia period, procedure period, and postprocedure
period) and the minimum, medium, and maximum heart rates (HRs) were
included as electrocardiographic variables studied.
Specific records were also conducted at 3 time points during the dental
treatment (at the beginning of the basal period, 15 minutes after the
anesthesia application, and at the end of the procedure) by the 12-lead
electrocardiography, digital sphygmomanometry for blood pressure (BP),
and assessment of the Facial Image Scale for anxiety.
Corrected QT (QTc) interval in LQTS patients was calculated using
Bazett’s formula (QTc=QT interval/RR interval), preferably in lead II,
or V2 and V5. QTc values >460 ms for women were considered
abnormal24. The QT
interval was manually measured from the beginning of the QRS complex to
the end of the T wave from all 12 leads using the tangent method.
Whenever the end of the T wave could not be determined in any given
lead, this lead was excluded from the analysis. The same cardiologist
NQSO made all measurements, later confirmed by a second cardiologist
FCCD, both blinded to the patients’ data. Occasional disagreements were
resolved by consensus. Changes in QTc (categorized in >10%
of shortening or lengthening of QTc) were also analyzed.
For patients with BrS, an additional high right precordial lead was
included to observe the possible occurrence of dynamic changes during
the phases of the dental procedure.
Possible device shocks or ICD therapies were scheduled to be analyzed in
all patients by the medical team, independently of any therapies. We
also analyzed the morphological pattern of dynamic changes in the right
precordial leads in patients with BrS, as previously described22.