Magnetic Navigation May Increase Ablation Efficacy
Magnetic fields help guide the wire tip to the desired location.
When used in patients with hypertrophic obstructive cardiomyopathy, magnetically guided alcohol septal ablation can dramatically reduce symptoms, echo gradient and septal thickness and improve excersice tolerance at three months, according to a study from the Methodist DeBakey Heart Center in Houston (Figure).
“Magnetic assisted interventions have the potential to increase the efficacy of alcohol septal ablation in these patients,” the researchers concluded.
Using a magnetic navigation system (Niobe System, Stereotaxis, St. Louis), researchers led by John Buergler, MD, an interventional cardiologist at the DeBakey center, performed alcohol septal ablation in 29 consecutive patients with hypertrophic obstructive cardiomyopathy (HOCM) and medically refractory angina.
The magnetic system was used in the hopes of improving upon traditional septal ablation.
Septal ablation can be challenging due to its takeoff from the left anterior descending artery and/or small size.
Improved outcomes
At three months, the New York Health Association class improved from 3.2 ± 0.4 to 1.5 ± 0.9 (P < .001). Angina class improved from 1.9 ± 1.0 to 1.2 ± 0.5 (P < .01).
The pressure gradient decreased from 70 mm Hg ± 33 to 32 mm Hg ± 32 (P < .001).
Septal thickness decreased from 1.9 mm ± 0.3 to 1.4 mm ± 0.4 mm (P < .001). Myocardial oxygen consumption improved from 14.6 mL/kg/min ± 4.0 to 17.8 mL/kg/min ± 2.7 (P < .001).
The modified Bruce protocol treadmill time also improved from 7.2 ± 4.1 minutes to 9.8 ± 4.3 minutes (P < .001).
According to the researchers, these dramatic improvements warrant additional studies to further define the value of magnetically guided alcohol septal ablation in HOCM patients.
Magnetic system
The system uses magnetic fields to guide the wire tip to a specific location in the vessels or within the heart.
The magnets are enclosed in a stationary housing on either side of the patient table in the catheterization laboratory.
The magnetic fields are less than 10% of the fields generated by magnetic resonance imaging equipment.