The TP related complications are given in Table Pericardial
The TP-related complications are given in Table 3. Pericardial effusion without tamponade was seen in 2 patients (5.9%) in the TEE-guided TP group and 5 (8.8%) in the fluoroscopy-guided group. There was no pericardial tamponade in the TEE-guided group and only one patient experienced tamponade in the fluoroscopy-guided group. One patient in the fluoroscopy-guided group had a transient ischemic attack (TIA) manifesting as right limb weakness that completely resolved before discharge. Diaphragm paralysis was seen in 2 patients (5.9%) vs. 4 (7%) in the TEE-guided group and fluoroscopy-guided group, respectively. Gastroparesis was seen in 3 patients in the fluoroscopy-guided group, whereas none of the patients in the TEE-guided group had gastroparesis. Inguinal hematoma and/or pseudoaneurysm was seen in 3 patients (8.8%) in the TEE-guided TP group and 4 (7.0%) in the fluoroscopy-guided group. None of the study patients required emergent surgery. Total complications seen were 7 (20.6%) and 18 (31.6%) in the two groups. All complication parameters were similar between groups (Table 3).
Table 4 shows the procedural success and recurrence rates. There was no statistical difference in these parameters between groups.
Discussion Previous studies suggest indirectly that the use of echocardiography may increase procedural safety, but to date, there are no data to prove this directly. We showed a similar trend in the present study. However, because of the small size of our study group, it was not possible to show a statistically significant ap-1 transcription factor in complication rates by using TEE guidance during the procedure. Conventionally, the procedure is performed under fluoroscopic guidance and pressure monitoring. In experienced hands, various modifications of this method have a reasonable safety profile. However, serious complications such as cardiac tamponade (1.31%) or aortic perforation can still occur and can lead to death (0.15%) [3,4]. To reduce the incidence of such complications, TP can be done under TEE or ICE guidance. TEE necessitates a higher level of sedation and is often not tolerated well. ICE requires additional expertize and remarkably increases procedural cost. In our study, we used TEE as a guide because of the lower procedural cost. An important advantage of echocardiographic guidance during TP is the possibility of initiating anticoagulation safely before TP. This appears to be a very important benefit, especially in patients with AF, in whom the risk of thrombus formation is high, despite anticoagulation to ACT >250s. In one study, the incidence of thrombosis was significantly lower when heparin was given before the first or second TP compared with heparin administration after the TP (3.1% vs. 9%, p<0.001). A thrombus was observed on a mapping or ablation catheter in 16 of 29 patients, and in the remaining 13, it was detected in the left atrium or appendage. Additionally, a thrombus aspiration was safely performed through the sheath in 21 of 29 cases . In our study, we also aimed to evaluate the advantages of echocardiographic guidance during TP by initiating anticoagulation safely before TP, but only one patient in the fluoroscopy-guided group experienced a thromboembolic event, which was not statistically different from the TEE-guided group. Although in our study the TEE probe was removed after successful TP, there are many other possible advantages of continuous TEE usage during the cryoablation of AF. Siklódy et al.  studied 124 PVs in 30 patients. Under continuous TEE assessment, a cryoballoon was placed in the antrum of each PV aiming for complete PV occlusion as documented by color Doppler. They reported that, compared to their previously published data , times with the cryoballoon were shorter (including both ablation time and mapping time after ablation), similar to previously published cryoballoon data . Fluoroscopy times were not longer and tended to be shorter at the end of the study, as they had advanced in their learning curve. They also noted that TEE allowed them to observe some undescribed phenomena, as well as to resolve them during the procedure. Whenever PV occlusion cannot be achieved, particularly by complex anatomies such as extremely oval PV or supplementary right-sided PVs, echocardiography precisely localized the site of leakage and permitted the development of alternative strategies. In the last cases of their series, oval PVs were successfully ablated by freezing the balloon at the cranial part of the PV antrum, and then pulling it gently back after approximately 45s under attentive TEE supervision, aiming to close the gap by slightly pulling the frozen PV balloon toward the caudal aspect of the antrum. This maneuver could only be echocardiographically documented, as contrast fluid could not be injected through the balloon once the temperature fell below 0°C. Whenever this last “pull-back” strategy was not feasible, the PV antrum was ablated in 2 stages, sequentially aiming at the cranial and the caudal aspects of the PV antrum. Supplementary right-sided PVs were specifically targeted by selecting them with the guidewire: this approach permitted the creation of more complete overlapping lesions around the septal PVs, as it includes LA tissue located between the superior and the inferior septal PV. Additionally, they reported that TEE also avoided inflating the balloon across the interatrial septum while attempting to isolate a right inferior PV. In the study of Siklody et al., all patients underwent a computed tomography scan, 3D anatomical models of the LA were reconstructed, and if all PVs presented a diameter <18mm, the PV isolation was performed using a 23-mm diameter cryoballoon. If any PV was >18mm, they chose a 28-mm balloon (Arctic Front, Cryocath, Montreal, Quebec, Canada, 11-Fr shaft size) in order to create wider lesions including part of the LA surrounding the PV. The main observed complication was a transient phrenic nerve paralysis. The ratio between the vein size and the balloon size seems to play a crucial role in the appearance of this complication [15,16]. TEE has been reported as strongly correlated to magnetic resonance (MR) angiography in assessing PV anatomy , and Peyrol et al.  suggested that TEE was an easily available and effective tool to select the cryoballoon size for PVI according to evaluated PV diameters and anatomy. Instead of using MR angiography for evaluating the PV diameter and selecting the cryoballoon size, we think that it is reasonable to use TEE. This way, continuous TEE usage can enable us to evaluate the size of right-sided PVs before choosing the balloon size and a large balloon can be preferred. Although cryoballoon positioning at the PV antrum may be influenced not only by the TP site but also by the anatomical findings of both the left atrium and the PV antrum in each case, TEE-guided TP can shorten fluoroscopy, total cryoablation, and total procedural times. Importantly, it can also facilitate cryoablation of inferior pulmonary veins.