Characterizing lesion morphology of a novel diamond-tip temperature-controlled irrigated radiofrequency ablation catheter

BACKGROUND

The DiamondTemp ablation (DTA) system is a novel temperature-controlled irrigated radiofrequency (RF) ablation system that accurately measures tip-tissue temperatures for real-time power modulation. Lesion morphologies from longer RF durations with the DTA system have not been previously described. We sought to evaluate lesion characteristics of the DTA system when varying the application durations.

METHODS

A bench model using porcine myocardium was used to deliver discrete lesions in a simulated clinical environment. The DTA system was power-limited at 50 W with temperature set-points of 50 °C and 60 °C (denoted Group_50 and Group_60). Application durations were randomized with a range of 5-120 s.

RESULTS

In total, 280 applications were performed. Steam pops were observed in five applications: two applications at 90 s and three applications at 120 s. Lesion size (depth and maximum width) increased significantly with longer applications, until 60 s for both Group_50 and Group_60 (depth: 4.5 ± 1.2 mm and 5.6 ± 1.3 mm; maximum width: 9.3 ± 2.7mm and 11.2 ± 1.7mm, respectively). As lesions transition from resistive to conductive heating (longer than 10 s), the maximum width progressed in a sub-surface propagation. Using a "Time after Temperature 60 °C" (TaT60) analysis, depths of 2-3 mm occur in 0-5 s and depths plateau at 4.6 ± 0.8 mm between 20 and 30 s.

CONCLUSIONS

The DTA system rapidly creates wide lesions with lesion depth increasing over time with application durations up to 60 s. Using a TaT60 approach is a promising ablation guidance that would benefit from further investigation.

Initial experience of temperature-controlled irrigated radiofrequency ablation for ischaemic cardiomyopathy ventricular tachycardia ablation

BACKGROUND

The DiamondTemp ablation (DTA) catheter system delivers high power, open-irrigated, temperature-controlled radiofrequency (RF) ablation. This novel ablation system has not been previously used for ventricular tachycardia (VT) ablation.

OBJECTIVE

Feasibility of using the DTA catheter system for VT ablation in ischaemic cardiomyopathy (ICM) patients.

METHOD

Ten ICM patients with optimal anti-arrhythmic drug therapy and implantable cardiac defibrillators (ICD) were recruited. VT inducibility testing was performed at the end of the procedure. ICD data for device detected VT episodes and device treated VT episodes were collected for 6-months pre- and post-ablation.

RESULTS

Substrate analysis demonstrated reductions in the borderzone area of 4.4 cm² (p = 0.026) and late potential area of 3.5 cm² (p = 0.0449) post-ablation, with reductions in the mean bipolar and unipolar voltages of the ablation target areas (0.14 mV (p = 0.0007); 0.59 mV (p = 0.0072) respectively). Complete procedural success was achieved in 9 procedures. Post-ablation VT inducibility testing was not performed in 1 procedure due to a steam pop complication resulting in pericardial tamponade requiring drainage. Mean follow-up of 214 ± 33 days revealed an 88% reduction in total VT episodes (n = 266 median 16 [IQR 3-57] to n = 33 median 0; p = 0.0164) and 77% reduction in ICD therapies (n = 128 median 5 [IQR 2-15] to n = 30 median 0; p = 0.0181).

CONCLUSION

The DTA system resulted in adequate lesion characteristics with effective substrate modification, acute procedural success and improved outcomes at intermediate-term follow-up. Randomised controlled trials are required to compare the performance of the DTA system against conventional ablation catheters.

Rare cause of pulmonary cavitation in a 75-year-old man

A 75-year-old man of Asian descent presented to the acute medical unit with signs and symptoms suggestive of a community-acquired pneumonia. He had multiple comorbidities and was relatively immunocompromised as a result. Initial investigations supported the diagnosis of community-acquired pneumonia complicated by a cavitating lung lesion, and the patient was treated as per hospital guidelines. He continued to deteriorate despite appropriate therapy and developed a hydropneumothorax, requiring the insertion of a chest drain. A diagnosis of pulmonary mucormycosis (Rhizopus microsporus) was made based on microbiology results from pleural aspirate, and patient was treated with intravenous antifungals. The patient was referred to the thoracic team for consideration of surgical intervention but was not suitable due to his multiple comorbidities. This case highlighted the importance of early consideration of fungal infection in patients with multiple risk factors and the need for aggressive therapy to ensure the best outcome.

Regular and frequent feedback of specific clinical criteria delivers a sustained improvement in the management of diabetic ketoacidosis

Efficient management of diabetic ketoacidosis (DKA) improves outcomes and reduces length of stay. While clinical audit improves the management of DKA, significant and sustained improvement is often difficult to achieve. We aimed to improve the management of DKA in our trust through the implementation of quality improvement methodology. Five specific targets (primary drivers: fluid prescription, fixed rate intravenous insulin infusion, glucose measurement, ketone measurement and specialist referral) were selected following a baseline audit. Interventions (secondary drivers) were developed to improve these targets and included monthly feedback to departments of emergency medicine, acute medicine, and diabetes. Following our intervention, the mean average duration of DKA reduced from 22.0 hours to 10.2 hours. We demonstrate that regular audit cycles with interventions introduced through the plan-do-study-act model is an effective way to improve the management of DKA.