Pulsing microwave energy: a method to create more uniform myocardial temperature gradients med./bio.

To study the effects of pulsing microwaves on the temperature gradient in an in vitro ovine endocardial model.

Microwave energy is a possible technique to create large myocardial lesions (e.g. for catether ablation). Microwave ablation may result in prolonged and excessive heating of the endocardium, resulting in thrombus formation.
The authors hypothesized that pulsing of microwave energy might cool the endocardium sufficiently to create a surface temperature similar to the temperature at depth.

• excised sections of ovine left ventricular tissue

Maximum temperatures at 0.5 mm were significantly lower at 63.2 +/- 5.89°C for the 1-second pulse compared with 83.5 +/- 7.31°C for the continuous energy delivery.
Pulse configurations "3 seconds on-3 seconds off" and "5 seconds on-5 seconds off" also resulted in a significantly lower surface temperature than continuous energy delivery. However, temperatures at the 2.0 mm and 3.5 mm depth generated by the pulsing delivery were similar to those temperatures achieved during continuous energy delivery.
These techniques may prevent the excessive endocardial damage that may result in an increased risk of thrombus formation and embolization.