Effective Use of Pecs and Transversus Thoracics Plane Blocks for Subcutaneous Cardiac Pacemaker Insertion: A Case Series

Participants that undergo permanent cardiac pacemaker implantation can often present with challenging anesthetic management plans for the anesthesia provider. Typically, these procedures are performed in electrophysiology labs that are often in remote locations away from the main operating room suite. This presents the logistic challenges of not having standard anesthesia machines, equipment and medications readily available for these cases.Currently, the majority of these cases are done under local anesthesia with light to moderate sedation. However, when it comes to inserting more complex devices such as implantable cardiac defibrillators and cardiac resynchronization therapy devices, participants may not be able to tolerate these more invasive and painful procedures with only local anesthetic as the primary mode of analgesia.

Ultrasound-guided regional anesthetic techniques, in particular the pectoralis nerve blocks (PEC I and II) and the Transversus Thoracic Muscle plane block (TTP), offer an alternative mode of analgesia for these participants. PEC I blocks target the lateral and medial pectoral nerves by injecting local anesthetic in the fascial plane between the pectoralis major and minor muscles. PEC II blocks supplement the PEC I block by targeting the intercostal nerves with local anesthetic injected between the pectoralis minor and serratus anterior muscles. The transversus thoracic plane block targets the anterior cutaneous branches of the intercostal nerves. In combination, these four blocks would provide analgesia of the upper anterior chest wall.(3)These would provide effective analgesia of the upper anterior chest wall.(7).

However, there is a paucity of studies on the use of PEC blocks in cardiac pacemaker implantation procedures. There is a case report from 2014 on a 71 year-old male with an ejection fraction of 20% undergoing CRTD implantation, which showed that PECs block with moderate sedation using dexmedetomidine could be safely utilized to provide effective analgesia for the procedure.11 However, this was not a subcutaneous ICD that required tunneling of the coils. Thus there are no randomized controlled studies to investigate whether the use of peripheral nerve blocks as primary anesthetic choice could be a viable alternative for multiple participants undergoing subcutaneous ICD placement.

This is a randomized controlled study evaluating the effectiveness of PEC I, PEC II, Transversus Thoracic plane blocks as the primary anesthetic in participants undergoing subcutaneous implantable defibrillator. There will be two groups; the nerve block group vs. general anesthesia group. The participants in the nerve block group will receive an ultrasound-guided nerve block in the electrophysiology suite prior to the start of the procedure. Participants will get a PEC I block with 10ml of 0.375% ropivacaine, PEC II block with 15ml of 0.375% ropivacaine, 15ml of 0.375% ropivacaine for TTP. PEC I block entails injecting local anesthesia between the pectoralis major and pectoralis minor muscles to anesthetize the medial and lateral pectoral nerves. PEC II block entails injecting local anesthetic between the pectoralis minor and serratus anterior muscles to block the upper intercostal nerves. For Tranversus Thoracic Plane block, local anesthetic will be injected between the internal intercostal muscle and the Transversus Thoracic muscle. The participants in the nerve block group will get mild sedation during the nerve blocks (midazolam 1-2mg IV and fentanyl 50-100mcg IV). After block placement, patient will be given a 0.3mcg/kg bolus of dexmedetomidine, then an infusion of dexmedetomidine 0.4mcg/kg/hr- 0.7mcg/kg/hr r +/- propofol 25mcg/kg/min-100mcg/kg/min for sedation. The general anesthesia group of participants will get the current standard of care with an endotracheal tube with a combination of IV induction medications and volatile anesthetic. Research assistant will hand an enclosed envelope to the anesthesiologists with the name of the group consented patient will be in.

Intraoperatively, the anesthesiologist will note if supplemental opioids and local anesthetic was required. Postoperatively, the PACU nurse will be asked to document pain scores according to the Visual Analog Scale (VAS) and total dose of opioids given. The distribution of the sensory block and motor weakness will be documented in the anesthesiologist's PACU discharge note. For postoperative data collection, opioid consumption totals and the pain scores at 30 minutes after arrival in PACU and at discharge.

Eligibility Criteria:
Inclusion Criteria:

* Patient undergoing cardiac pacemaker placement Age 18 and above ASA II-IV

Exclusion Criteria:

* Patient refusal
* Inability to understand and sign consent
* Infection at the injection site
* Known allergy or hypersensitivity to ropivacaine or other amide local anesthetics
* Coagulopathy (INR \> 1.5)
* Use of anticoagulant drugs that have not been discontinued in an appropriate amount of time before the surgery