Role of Ablation Therapy in Ventricular Arrhythmias

Coronary vessel detection methods for organ-mounted robots

BACKGROUND

HeartLander is a tethered robot walker that utilizes suction to adhere to the beating heart. HeartLander can be used for minimally invasive administration of cardiac medications or ablation of tissue. In order to administer injections safely, HeartLander must avoid coronary vasculature.

METHODS

Doppler ultrasound signals were recorded using a custom-made cardiac phantom and used to classify different coronary vessel properties. The classification was performed by two machine learning algorithms, the support vector machines and a deep convolutional neural network. These algorithms were then validated in animal trials.

RESULTS

Accuracy of identifying vessels above turbulent flow reached greater than 92% in phantom trials and greater than 98% in animal trials.

CONCLUSIONS

Through the use of two machine learning algorithms, HeartLander has shown the ability to identify different sized vasculature proximally above turbulent flow. These results indicate that it is feasible to use Doppler ultrasound to identify and avoid coronary vasculature during cardiac interventions using HeartLander.

Epicardial unipolar radiofrequency ablation for left ventricular aneurysm related ventricular arrhythmia

We report a case of a 62-year-old Chinese man with typical triple-vessel lesions and apical left ventricular aneurysm accompanied with ventricular tachycardia. Off-pump coronary artery bypass (OPCAB) grafting was performed in combination with epicardial unipolar radiofrequency ablation and linear closure of left ventricular aneurysm. The patient recovered well without postoperative complications. Holter monitoring showed no recurrence of the ventricular arrhythmia and the attack frequency of arrhythmia decreased significantly. The patient has been angina-free for 25 months since the operation and shows increasing exercise tolerance. Thus, left ventricular aneurysm plication combined with epicardial unipolar radiofrequency ablation during OPCAB may be beneficial for patients with ventricular aneurysm and preoperative malignant ventricular arrhythmia.

Biological therapies for cardiac arrhythmias: can genes and cells replace drugs and devices?

Cardiac rhythm disorders reflect failures of impulse generation and/or conduction. With the exception of ablation methods that yield selective endocardial destruction, present therapies are nonspecific and/or palliative. Progress in understanding the underlying biology opens up prospects for new alternatives. This article reviews the present state of the art in gene- and cell-based therapies to correct cardiac rhythm disturbances. We begin with the rationale for such approaches, briefly discuss efforts to address aspects of tachyarrhythmia, and review advances in creating a biological pacemaker to cure bradyarrhythmia. Insights gained bring the field closer to a paradigm shift away from devices and drugs, and toward biologics, in the treatment of rhythm disorders.

Effectiveness of catheter ablation of ventricular tachycardia in elderly patients with structural heart disease

INTRODUCTION AND OBJECTIVES

The implantable cardioverter-defibrillator (ICD) is a well-recognized means of providing effective treatment for patients with ventricular tachycardia (VT) and structural heart disease. However, the benefits of these devices in patients with limited life-expectancy have been questioned. Moreover, the long-term efficacy of catheter ablation of VT in this setting is unknown.

METHODS

This study involved 33 consecutive patients aged over 75 years with structural heart disease who underwent catheter ablation of VT. We investigated the efficacy of the procedure and its complications, and evaluated patient outcomes during follow-up.

RESULTS

The patients' mean age at the time of the procedure was 79.7 (3.7) years. Twenty-seven had ischemic heart disease and 6 had dilated cardiomyopathy. Their mean left ventricular ejection fraction (LVEF) was 35.9 (8.9%). Ablation of clinical VT was successful in 28 patients (84.8%). There were no statistically significant differences in the efficacy of ablation between patients with post-infarction scars (88.9%) and those with dilated cardiomyopathy (66.7%; P=.17). An ICD was implanted after the procedure in 4 patients. Complications associated with the procedure occurred in only 3 patients. Twenty patients were contacted later, after a mean follow-up period of 38.5 (27.7) months. Nine (mean age, 82.2 [4.6] years) were still alive and reported a good quality of life, without recurrent arrhythmias.

CONCLUSIONS

Catheter ablation of VT in elderly patients with structural heart disease appeared to be effective and relatively safe. It could provide an alternative to ICD implantation in this patient group.

Anthropomorphic simulator for minimally invasive epicardial access procedures

We have developed a prototype, in vitro anthropomorphic model for simulating pressure-guided, subxiphoid access procedures done to enable minimally invasive epicardial cardiac procedures including treatments for ventricular tachycardia. Life-size replicas of the heart and lungs were modelled using anatomically accurate surrogates. The dynamic pressure-frequency profiles of simulated pericardial fluid surrounding the water-pumped replica heart were measured and validated against previously acquired human intrapericardial pressure observations (Pearson's r = 0.88, p < 0.001). In replicating access procedures for approaching and entering the pericardial space, the system produced physiologically appropriate pressure measurements at each intermediate point along the needle's insertion pathway. Details of construction and performance are presented and discussed.