From the Guidelines
A Micra pacemaker is placed through a minimally invasive transcatheter procedure, which is a relatively low-risk cardiac procedure, but it's essential to avoid early and unnecessary pacing, especially in patients with conduction system abnormalities post-MI, as the natural course is frequently associated with recovery of conduction 1. The procedure involves accessing the femoral vein in the groin using a large-bore catheter, through which the Micra device is delivered and advanced to the right ventricle of the heart under fluoroscopic guidance. Key steps in the placement process include:
- Delivering the Micra device through the catheter to the right ventricle
- Positioning the device against the right ventricular wall, typically in the septum or apex
- Securing the device using small nitinol tines that embed into the heart tissue
- Confirming proper placement by testing electrical parameters, including sensing, pacing threshold, and impedance The entire procedure typically takes 30-60 minutes and requires only conscious sedation rather than general anesthesia, highlighting the minimally invasive nature of the Micra pacemaker placement, which reduces complications associated with traditional pacemakers, as noted in the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1.
From the Research
Micra Pacer Placement
The placement of a Micra pacer is a medical procedure that involves the implantation of a small pacemaker device in the heart.
- The Micra pacemaker is a leadless single-chamber VVI pacing device, which means it does not have any leads or wires connecting it to the heart 2.
- The device is implanted through a minimally invasive procedure, where a small incision is made in the groin area and the device is inserted through a vein and guided to the heart using a catheter.
- The Micra pacemaker is then attached to the heart wall using small tines or screws, and the device is programmed to regulate the heart's rhythm.
Patient Selection and Outcomes
Patient selection is a key component of securing optimal patient outcomes with leadless pacing 2.
- The primary outcome of the Micra IDE trial was compared between successfully implanted patients with a primary pacing indication associated with atrial fibrillation (AF) or history of AF (AF group) and those without (non-AF group).
- The study found that nearly one-third of patients selected to receive Micra VVI therapy were for indications not associated with AF, and non-AF VVI patients required less frequent pacing compared to patients with AF.
- The risks associated with VVI therapy were low and did not differ in those with and without AF 2.
Risk Factors and Complications
Several studies have identified risk factors and complications associated with pacemaker implantation in patients with atrial fibrillation.
- Heart failure and permanent AF each nearly triple the odds of developing bradycardia requiring a permanent pacemaker 3.
- Anticoagulation is markedly underutilized in reducing stroke risk in patients with permanent pacemakers and AF 4.
- Catheter ablation for patients with tachycardia-bradycardia syndrome was associated with a significantly lower rate of cardiovascular-related hospitalization and thromboembolic events compared to pacing 5.