Introduction-The long-term complications of catheter ablation within the pulmonary veins are unknown. The development of pulmonary vein stenosis has recently been described after catheter ablation to treat either chronic or paroxysmal atrial fibrillation. The purpose of this study was to examine the pathological and hemodynamic effects of radiofrequency (RF) energy application within the pulmonary veins. Methods and Results-Right heart and transseptal catheterization were performed in 9 anesthetized mongrel dogs. The pulmonary vein ostia were cannulated and pulmonary venous pressure was measured before RF energy application in up to 4 separate pulmonary veins. Animals were euthanized at intervals of 2 to 4 weeks (nϭ3), 6 to 8 weeks (nϭ3), or 10 to 14 weeks (nϭ3) after ablation. Repeat catheterization before euthanasia demonstrated statistically significant differences in pulmonary capillary wedge pressure, cardiac output, pulmonary vascular resistance, and systemic vascular resistance (PϽ0.05) compared with the baseline. Luminal narrowing was observed in 22 of 33 pulmonary veins to which RF energy was applied. Of these, 7 were totally occluded, 7 had severe stenosis, and 8 were only minimally narrowed. Histological examination revealed intimal proliferation with organizing thrombus, necrotic myocardium in various stages of collagen replacement, endovascular contraction, and a proliferation of elastic lamina. Conclusions-Applications of RF current within the pulmonary veins may result in pulmonary vein narrowing or complete occlusion. These observations should be considered in treatment of arrhythmias originating within the pulmonary veins.
Our purpose was to document and investigate the prognostic significance of features seen on MRI of patients with whiplash injury following relatively minor road traffic crashes. MRI was obtained shortly and at 6 months after the crash using a 0.5 T imager. The images were assessed independently by two radiologists for evidence of fracture or other injury; loss of lordosis and spondylosis were also recorded. Clinical examinations were used to assess the status of patients initially and at 6 months. The results of the independent MRI and clinical investigations were then examined for association using statistical tests. Initial MRI was performed on 29 patients, of whom 19 had repeat studies at 6 months; 48 examinations were thus examined. Apart from spondylosis and loss of lordosis, only one abnormality was detected: an intramedullary lesion consistent with a small cyst or syrinx. There were no statistically significant associations between the outcome of injury and spondylosis or loss of lordosis. No significant changes were found when comparing the initial and follow-up MRI. It appears that MRI of patients with relatively less severe whiplash symptoms reveals a low frequency of abnormalities, apart from spondylosis and loss of lordosis, which have little short-term prognostic value. Routine investigation of such patients with MRI is not justified in view of the infrequency of abnormalities detected, the lack of prognostic value and the high cost of the procedure.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.