Ablation of Frequent PVCs

Dr. John Strobel, Internal Medicine Associates, Bloomington Hospital, Bloomington, Indiana

Dr. John Strobel, Internal Medicine Associates, Bloomington Hospital, Bloomington, Indiana

Background The patient was a 33-year-old white female who presented with symptoms of dyspnea, palpitations, and fatigue that had been present for six months. A 48-hour Holter monitor demonstrated 68,356 premature ventricular complexes (PVCs). This represented 26% of all ventricular complexes. She also had significant amounts of bigeminy and trigeminy. An ECG demonstrated monomorphic PVCs that had a right bundle branch block, inferior axis morphology with a transition in lead V3. Echocardiography and stress testing were normal. She was treated with beta blockers for at least three months, but had no improvement in her symptoms. She did not desire long-term antiarrhythmic drug therapy because she feared side effects, especially fatigue. She was a young mother and was concerned about having the energy to care for her children. An electrophysiology study to map the arrhythmia was offered. Case Study To facilitate initially advancing the EnSite Array™ mapping catheter (St. Jude Medical, St. Paul, Minnesota) into the right ventricle, a diagnostic coronary angiography catheter was utilized to direct a stiff Amplatz guidewire into the pulmonary artery. The EnSite Array was then advanced over this guidewire into the right ventricular outflow tract. The 5F St. Jude Medical CRD-2 quadripolar catheter was placed via the right femoral vein at the His bundle. A 7F St. Jude Medical Safire 4-mm-tip ablation catheter was also advanced via the right femoral vein into the right ventricle and was used to create a three-dimensional (3D) geometry. The patient continued to have frequent PVCs during the procedure, although the frequency of these diminished after she received sedation to alleviate discomfort. With programmed stimulation, the patient did not have inducible ventricular tachycardia (VT). Infusion of isoproteronol did not significantly increase the frequency of the PVCs and did not result in VT induction. Using the EnSite Array mapping catheter, the PVCs were localized to the posterior right ventricular outflow tract (RVOT). At the site of earliest activation identified by the EnSite Array, the local electrograms were presystolic, and pacing from this site resulted in an identical match to the spontaneous PVCs. The first radiofrequency lesion resulted in a marked reduction in the PVC frequency. The second lesion completely eliminated all PVCs. Six additional radiofrequency lesions were delivered around the site of successful ablation to “blanket” the focus. The duration of the procedure was less than three hours, which included a one-hour period of observation in the EP lab following elimination of the PVCs, during which time sedation was allowed to abate and her rhythm was monitored for possible recurrence of PVCs.  Discussion The EnSite Array allowed the PVC focus to be quickly and accurately mapped. Using only activation and pace mapping, identification of a PVC focus can be tedious and long. Although preparing and placing the EnSite Array does consume some time on the front end of the procedure, it very quickly makes up for it by reducing the time spent mapping the arrhythmia. Creating a complete 3D geometry is very important but takes very little time, usually less than 10 minutes. Identifying the arrhythmia focus is then almost instantaneous. The EnSite Array uses 64 electrodes to collect 3,000 electrical data points. This allows for very accurate and precise localization of the arrhythmia focus. Although it wasn’t a particular issue in this case, the other advantage of using the EnSite Array is that only a single beat is required to localize the arrhythmia. In some instances, the PVCs may decline in frequency during the procedure due to sedation or other reasons. With the EnSite Array, this potential pitfall is eliminated. The patient was observed overnight in the hospital on telemetry and exhibited rare PVCs. One month later, a 24-hour Holter was repeated to quantitate her PVCs. She had none, and her symptoms had significantly improved.  About RVOT PVCs Although, in general, premature ventricular complexes are a benign phenomenon and most patients can simply be given reassurance without other therapy, there are instances where PVCs can be quite troublesome. Some patients may exhibit extremely frequent PVCs that cause almost constant symptoms of palpitations, fatigue, chest pain, or dizziness. In addition, it is now recognized that PVCs, especially those arising from the right ventricular outflow tract (RVOT), can cause left ventricular dysfunction, so elimination of the PVCs can reverse the cardiomyopathy. Takemoto et al1 reported on a group of 45 patients with frequent PVCs. In the subgroup in whom the PVCs accounted for >20% of all ventricular beats, LV dysfunction was frequently present, but normalized 6-12 months following ablation of the RVOT PVCs. Similarly, Yarlagadda et al2 reported that in a group of 27 patients with an average of over 17,000 PVCs per day, eight had LV dysfunction. Again, elimination of the PVCs by ablation resulted in normalization of their LV function. This study also implied that patients who developed cardiomyopathy were older, suggesting that patients who are older are more likely to develop cardiomyopathy or that the cardiomyopathy has had more time to develop. Conclusion The EnSite Array mapping catheter allows for rapid and accurate mapping of focal arrhythmias. Procedures such as this one, which used to be time-consuming and tedious, are now quite routine. Disclosure: The author has disclosed that he has a financial relationship with the company (St. Jude Medical) that produces or markets products or services relevant to the topic of this manuscript.