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.