Incidence Of Phrenic Nerve Injury Research Articles

A randomized controlled trial of the size-adjustable cryoballoon vs conventional cryoballoon for paroxysmal atrial fibrillation: The CONTRAST-CRYO II trial rationale and design

BackgroundPulmonary vein isolation (PVI) with cryoballoon technology is a well-established therapy for atrial fibrillation (AF) patients. Most recently, a size-adjustable cryoballoon (POLARx FIT) that enables delivery as a standard 28mm or expanded 31mm size was introduced. ObjectiveThe study sought to perform a randomized clinical trial to evaluate the safety and efficacy of this novel cryoballoon as compared to the conventional cryoballoon. MethodsThe CONTRAST-CRYO II trial is a multicenter, prospective, open-label, randomized controlled trial in which 214 patients with paroxysmal AF will be randomized 1:1 to receive cryoballoon ablation with either a conventional cryoballoon (Arctic Front AdvanceTM Pro) or size-adjustable cryoballoon. This study was approved by the Institutional Review Boards at all investigational sites and has been registered in the UMIN Clinical Trials Registry (UMIN000052500). ResultsThe primary endpoint of this study will be the incidence of phrenic nerve injury. The secondary endpoints include the procedure success, chronic success through 12 months, procedure-related adverse events, biophysiological parameters during applications for each PV, total procedure and fluoroscopy time, level of the PVI and isolation area, and probability of non-PV foci initiating AF. ConclusionThe CONTRAST-CRYO II trial is a multicenter, prospective, randomized controlled trial designed to assess the safety and efficacy of the POLARxTM FIT by comparing the AFA-Pro. The findings from this trial will provide additional utility data on the efficacy of the size-adjustable cryoballoon for isolating pulmonary veins in patients with paroxysmal AF.

Incidence of phrenic nerve injury during pulmonary vein isolation using different cryoballoons: data from a large prospective ablation registry.

Phrenic nerve injury (PNI) is the most common complication during cryoballoon ablation. Currently, two cryoballoon systems are available, yet the difference is unclear. We sought to compare the acute procedural efficacy and safety of the two cryoballoons. This prospective observational study consisted of 2,555 consecutive atrial fibrillation (AF) patients undergoing pulmonary vein isolation (PVI) using either conventional (Arctic Front Advance) (AFA-CB) or novel cryoballoons (POLARx) (POLARx-CB) at 19 centers between January 2022 and October 2023. Among 2,555 patients (68.8 ± 10.9 years, 1,740 men, paroxysmal AF[PAF] 1,670 patients), PVIs were performed by the AFA-CB and POLARx-CB in 1,358 and 1,197 patients, respectively. Touch-up ablation was required in 299(11.7%) patients. The touch-up rate was significantly lower for POLARx-CB than AFA-CB (9.5% vs. 13.6%, p = 0.002), especially for right inferior PVs (RIPVs). The touch-up rate was significantly lower for PAF than non-PAF (8.8% vs. 17.2%, P < 0.001) and was similar between the two cryoballoons in non-PAF patients. Right PNI occurred in 64(2.5%) patients and 22(0.9%) were symptomatic. It occurred during the right superior PV (RSPV) ablation in 39(1.5%) patients. The incidence was significantly higher for POLARx-CB than AFA-CB (3.8% vs. 1.3%, P < 0.001) as was the incidence of symptomatic PNI (1.7% vs. 0.1%, P < 0.001). The difference was significant during RSPV (2.5% vs. 0.7%, P < 0.001) but not RIPV ablation. The PNI recovered more quickly for the AFA-CB than POLARx-CB. Our study demonstrated a significantly higher incidence of right PNI and lower touch-up rate for the POLARx-CB than AFA-CB in the real-world clinical practice.

Phrenic Nerve Injury During Cryoballoon-Based Pulmonary Vein Isolation: Results of the Worldwide YETI Registry.

Cryoballoon-based pulmonary vein isolation (PVI) has emerged as an effective treatment for atrial fibrillation. The most frequent complication during cryoballoon-based PVI is phrenic nerve injury (PNI). However, data on PNI are scarce. The YETI registry is a retrospective, multicenter, and multinational registry evaluating the incidence, characteristics, prognostic factors for PNI recovery and follow-up data of patients with PNI during cryoballoon-based PVI. Experienced electrophysiological centers were invited to participate. All patients with PNI during CB2 or third (CB3) and fourth-generation cryoballoon (CB4)-based PVI were eligible. A total of 17 356 patients underwent cryoballoon-based PVI in 33 centers from 10 countries. A total of 731 (4.2%) patients experienced PNI. The mean time to PNI was 127.7±50.4 seconds, and the mean temperature at the time of PNI was -49±8°C. At the end of the procedure, PNI recovered in 394/731 patients (53.9%). Recovery of PNI at 12 months of follow-up was found in 97.0% of patients (682/703, with 28 patients lost to follow-up). A total of 16/703 (2.3%) reported symptomatic PNI. Only 0.06% of the overall population showed symptomatic and permanent PNI. Prognostic factors improving PNI recovery are immediate stop at PNI by double-stop technique and utilization of a bonus-freeze protocol. Age, cryoballoon temperature at PNI, and compound motor action potential amplitude loss >30% were identified as factors decreasing PNI recovery. Based on these parameters, a score was calculated. The YETI score has a numerical value that will directly represent the probability of a specific patient of recovering from PNI within 12 months. The incidence of PNI during cryoballoon-based PVI was 4.2%. Overall 97% of PNI recovered within 12 months. Symptomatic and permanent PNI is exceedingly rare in patients after cryoballoon-based PVI. The YETI score estimates the prognosis after iatrogenic cryoballoon-derived PNI. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03645577. Graphic Abstract: A graphic abstract is available for this article.

Predictors of Phrenic Nerve Injury During Pulmonary Vein Isolation for Curing Atrial Fibrillation With Balloon-Based Visually Guided Laser Ablation.

Pulmonary vein (PV) isolation (PVI) with balloon-based visually guided laser ablation (VGLA) is useful for treating atrial fibrillation (AF), but phrenic nerve injury (PNI) is an important complication. We investigated the predictors of developing PNI during VGLA.Methods and Results:We included 130 consecutive patients who underwent an initial VGLA of non-valvular paroxysmal AF. Twenty patients developed PNI during the PVI. The patients with PNI had a significantly larger right superior PV ostial area (RSPVOA) than the other patients (mean [±SD] 284.7±47.0 vs. 233.1±46.4 mm2, respectively; P<0.01). Receiver operating characteristic analyses revealed that the area under the RSPVOA curve was 0.79 (95% confidence interval [CI] 0.69-0.90) with an optimal cut-off point of 238.0 mm2(sensitivity, 0.58; specificity, 0.95). In multivariate analyses, a large RSPVOA (HR 1.02, 95% CI 1.01-1.03, P<0.01) and small balloon size (HR 0.70, 95% CI 0.50-0.99, P=0.04) were independent risk factors for PNI during VGLA. PNI remained in 13 patients after the procedure, but 12 of these patients recovered from the PNI during the follow-up period. The incidence of PNI during VGLA was relatively high, but PNI improved in most cases. A large RSPVOA and small balloon size were predictors of PNI during VGLA.

The advantages and disadvantages of the novel fourth-generation cryoballoon as compared to the second-generation cryoballoon in the current short freeze strategy

The novel fourth-generation cryoballoon (4th-CB) is characterized by a shorter-tip that potentially facilitates better time-to-isolation(TTI) monitoring. We sought to clarify the advantages and disadvantages of the 4th-CB compared to the second-generation cryoballoon (2nd-CB) inpulmonary vein isolation (PVI). Forty-one and 49 consecutive atrial fibrillation patients underwent 2nd-CB and 4th-CB PVIs using 28-mm balloons and short freeze strategies.When effective freezing was not obtained, the CB was switched to the other CB. The rate of successful PVIs was significantly higher for 2nd-CBs than 4th-CBs (162/162[100%] vs. 178/193[92.2%] PVs, p < 0.0001). Thedifference was significant for lower PVs, especially right inferior PVs (RIPVs)(p = 0.005). In a total of 15 PVs in 11 patients, 4th-CBs were switched to 2nd-CBs, and 14/15(93.3%) PVs were successfully isolated. The balloon temperature tended to reach -55℃ more frequently with 2nd-CBs than 4th-CBs duringRIPV ablations (15/41[36.6%] vs. 12/49[24.5%], p = 0.21). The TTI monitoring capability was significantly higher with 4th-CBs than 2nd-CBs(131/188[69.7%] vs. 83/160[51.9%] PVs, p = 0.0007). The difference was significant for right superior and left inferior PVs, but not for left superior PVs.Even if PVs requiring crossover were excluded, the total freeze duration (715±152 vs. 755±215 seconds, p = 0.31) tended to be shorter for 2nd-CBs than 4th-CBs. The incidence of phrenic nerve injury was similar for 2nd-CB and 4th-CB ablation (0/41 vs. 2/49, p = 0.12) CONCLUSIONS: The 4th-CB's shorter balloon tip enabled a significantly higher capability of TTI monitoring; however, it resulted in significantly lower rates of successful PVIs than the 2nd-CB, especially for the RIPVs.

Cryoballoon vs radiofrequency ablation of atrial fibrillation: insights from the Veterans Healthcare System.

Catheter ablation is considered the mainstay treatment for drug-refractory atrial fibrillation (AF). The aims of our study were to compare the efficacy and safety of the most two currently approved approaches (point-by-point radiofrequency ablation (RFA), either with contact force (CF) or without contact force (nCF) catheters, and cryoballoon ablation (CBA)) in the Veterans Healthcare System. We performed a retrospective study of patients who underwent ablation for treatment of AF at the veterans affairs healthcare system between 2013 and 2018. Only the first reported ablation procedure was included. We included 956 patients in the study (97.4% males, 91.5% Caucasians, 67% paroxysmal AF), with 682 patients in RFA-nCF, 139 in RFA-CF, and 135 in CBA. Thirty-day complication rates were comparable between the three groups with the exception of higher incidence of phrenic nerve injury in CBA group when compared to RFA-nCF (2.2% vs 0.0%, p < 0.01). Long-term recurrence rate of AF was significantly lower in the CBA group when compared to RFA-nCF (33.3% vs 47.7%, adjusted HR 0.60, 95% CI 0.44-0.83, p < 0.01). On the other hand, it was similar between RFA-CF and RFA-nCF groups (43.9% vs 47.7%, adjusted HR 1.01, 95% CI 0.76-1.33, p 0.97). After stratifying patients based on AF type, these findings were only present in patients with paroxysmal AF. CBA for paroxysmal AF, in male dominant patients' population, was associated with lower incidence of AF recurrence rate while having a comparable safety profile to RFA independent of the use of CF catheters.

6121Phrenic nerve injury during pulmonary vein isolation using the second-generation cryoballoon: characteristics and follow-up - The YETI registry

Abstract Background Second-generation cryoballoon (CB2) based pulmonary vein isolation (PVI) has emerged as a safe and effective treatment option for symptomatic atrial fibrillation (AF). Although published complication rates of CB2 based-PVI are relatively low and several safety algorithms have been implemented in the protocols the most frequent complication is right-sided phrenic nerve injury (PNI). The reported incidence of PNI varies from 2–5% of patients. However data on PNI characteristics as well as follow-up is sparse. Purpose We aimed to evaluate the incidence, characteristics and outcome of PNI during after CB2 based-PVI in a large patients population. Methods and results From July 2012 to November 2018 a total of 13693 patients received CB2 or CB3 (third-generation) based-PVI in 23 EP centers (Germany: 12, China: 1, Turkey: 3, Japan: 3, USA: 1, Austria: 1, Poland: 1, Swizerland: 1). A total of 596 (4.4%) of patients experienced PNI during treatment of the right superior (84%) right inferior (15%) right middle (0.3%) (and left superior (0.3%) pulmonary veins. The mean time to PNI was 127±51 seconds and the mean temperature at the time of PNI was −49±7 °C. The target PV was isolated at time of PNI in 84% of cases. The applications were interrupted using double-stop technique in (71%). In 212/306 (52%) a CMAP was utilized. At the end of the procedure PNI persistent in 45% of patients. Fluoroscopic or sonographic evaluation of PNI was performed 1–3 days after the procedure and revealed persistent PNI in 35% of patients. Dyspnea before discharge was reported in 18% of patients with persistent PNI. Patients follow up at 1–3, and 6–12 months included fluoroscopy and a visit in an outpatient clinic. After 1–3 months 18% of patients showed persistent PNI including 13% of patients complaining of dyspnea. After 6–12 months of follow-up including fluoroscopic evaluation PNI was persistent in 1.8% of patients while dyspnea was reported by 1.7% patients. Only 0.08% of the overall population of 13693 patients showed permanent and symptomatic PNI. Conclusion The incidence of PNI during CB2-based PVI is low. About 55% of PNI recovered until the end of the procedure. Most of PNI recovered within 12 months. Symptomatic permanent PNI is very rare in patients after CB2/CB3-based PVI.

Characteristics of Phrenic Nerve Injury During Pulmonary Vein Isolation Using a 28-mm Second-Generation Cryoballoon and Short Freeze Strategy.

BackgroundThe reported incidence of phrenic nerve injury (PNI) varies owing to different definitions, balloon generations, balloon size, freezing regimen, and protective maneuvers. We evaluated the incidence, predictors, and outcome of PNI during cryoballoon pulmonary vein isolation in a large population.Methods and ResultsFive hundred fifty atrial fibrillation patients underwent pulmonary vein isolation using one 28‐mm second‐generation cryoballoon and single 3‐minute freeze strategy under diaphragmatic compound motor action potential (CMAP) monitoring. A total of 34 (6.2%) patients experienced PNI during the right superior and inferior pulmonary vein ablation in 30 and 4 patients, respectively. Applications were interrupted using double‐stop techniques after 136 [104–158] second applications, and a pulmonary vein isolation was already achieved in all but one case. The baseline CMAP amplitude and timing of deflation (CMAP def) were 0.75±0.30 and 0.17±0.17 mV, respectively. Persistent atrial fibrillation, larger right superior pulmonary vein ostia, and deeper balloon positions were associated with higher incidences of PNI. The CMAP def predicted a PNI recovery delay, and the best cutoff value for predicting PNI recovery by the next day was 0.20 mV (sensitivity 57.1%, specificity 100%). Among 6 patients undergoing second procedures 8.5 (6.7–15.0) months later, the right superior pulmonary vein was durable in 3 with >120 second applications. Despite active balloon deflation, no significant pulmonary vein stenosis was observed in 15 right superior pulmonary veins evaluated 6 (5–9) months later. No patients had symptoms, and the PNI recovered 1 day and 1 month postprocedure in 21 and 4 patients, respectively.Conclusions PNI resulting from cryoballoon ablation was reversible. The double‐stop technique is safe, and immediate active deflation following a CMAP decrease appears to be essential for faster PNI recovery.

Phrenic nerve injury during right inferior pulmonary vein ablation with the second-generation cryoballoon: clinical, procedural, and anatomical characteristics.

There is still sparse information regarding phrenic nerve injury (PNI) during ablation of the right inferior pulmonary vein (RIPV) by means of the second-generation cryoballoon advance (CB-A). The aim of this study was to describe the procedural, anatomical, and clinical characteristics of patients who experienced PNI during the RIPV ablation. Consecutive patients who had undergone pulmonary vein isolation (PVI) using CB-A and suffered PNI during RIPV ablation were retrospectively included in our study. A cohort of patients who did not suffer any PNI was randomly included in a 1:3 ratio as a control group. The incidence of PNI during RIPV cryoapplication was 3.5%, (34 of 979 patients). There were no significant differences in clinical characteristics between patients with and without PNI. The prevalence of right common ostium (RCO) was significantly higher in patients with a PNI [4 patients (11.8%) vs. 1 patient (1.0%); P < 0.01]. A temperature drop velocity from the basal temperature to - 20 °C of 2.38 °C/s rendered a sensitivity of 82.4% and a specificity of 51.0% with a negative predictive value of 89.7%. Temperature drop velocity from basal to - 20 °C and the presence of an RCO were predictors of PNI in the multivariate analysis [odds ratio (OR) 7.27, 95% confidence interval (CI) 2.54-20.80; P < 0.01 and OR 18.41, 95%CI 1.87-181.23; P = 0.01, respectively). PNI during RIPV freeze might occur in around 3.5% of cases. The presence of an RCO and a fast temperature drop must prompt a careful monitoring of the phrenic nerve function during cryoapplications on the RIPV.

A ferromagnetic surgical system reduces phrenic nerve injury in redo congenital cardiac surgery

A ferromagnetic surgical system (FMwand®) is a new type of dissection device expected to reduce the risk of adjacent tissue damage. We reviewed 426 congenital cardiac operations with cardiopulmonary bypass through redo sternotomy to assess if this device prevented phrenic nerve injury. The ferromagnetic surgical system was used in 203 operations (47.7%) with regular electrocautery and scissors. The preoperative and operative details were similar between the operations with or without the ferromagnetic surgical system. The incidence of phrenic nerve injury was significantly lower with the ferromagnetic surgical system (0% vs 2.7%, P = 0.031). A logistic regression model showed that the use of the ferromagnetic surgical system was significantly associated with reduced odds of phrenic nerve injury (P < 0.001).

216-17: Femoral venous pressure waveform as indicator of PNI in CB ablation

Purpose: Femoral venous pressure waveform (VPW) analysis has been recently described as a novel method to assess phrenic nerve function during atrial fibrillation ablation procedures by means of cryoballoon (CB) technique. In this study we sought to evaluate the feasibility and effectiveness of this technique, with respect to the incidence of phrenic nerve injury (PNI), in comparison with the traditional abdominal palpation technique alone. Results: During the study period a total of 350 consecutive patients (male 67%, age 57.2 ± 12.9 years) were enrolled (200 using traditional phrenic nerve assessment and 150 using VPW monitoring). The incidence of PNI in the overall population was 8.0% (28/350); of these, 8 were impending PNI (2.3%), 14 transient (4.0%) and 6 persistent (1.7%). Patients having undergone CB-A with traditional assessment experienced 18 phrenic nerve palsies (9.0%) vs. 2 in “VPW monitoring” group (1.3%; p = 0.002). Specifically, the former presented 12 transient (6.0%) and 6 persistent (3.0%) phrenic nerve palsies, and the latter exhibited 2 transient (1.3%; p = 0.03) and no persistent (0%; p = 0.04) phrenic nerve palsies. Conclusions: In conclusion, this novel method assessing the VPW for predicting PNI is inexpensive, easily available, with reproducible measurements and appears to be more effective than traditional assessment methods.

Fluoroscopic position of the second-generation cryoballoon during ablation in the right superior pulmonary vein as a predictor of phrenic nerve injury.

Phrenic nerve injury (PNI) is the most frequently observed complication during pulmonary vein isolation procedure using the second-generation cryoballoon (CB). Our objective was to analyse the correlation between the fluoroscopic position of the 28 mm CB during ablation in the right superior pulmonary vein (RSPV) and the occurrence of PNI. A total of 165 patients having undergone the large 28 mm CB ablation were retrospectively reviewed. Positioning of the CB relative to the cardiac silhouette was classified under fluoroscopic guidance in antero-posterior projection during RSPV ablation. Regarding the lower half of the balloon, CB positioning was defined as follows: (A) completely inside the cardiac shadow; (B1) <1/3 outside the cardiac shadow; and (B2) ≥1/3 outside the cardiac shadow. Phrenic nerve injury occurred in 9.7% (16/165) during ablation in the RSPV. The occurrence of PNI was 0.9, 10.6, and 90.1% in positions A, B1, and B2, respectively (A vs. B1, P = 0.01; B1 vs. B2, P < 0.0001). Among other pre-procedural and procedural variables, the B2 position was the strongest independent determinant for predicting PNI at RSPV (P = 0.001, odds ratio: 119.9; 95% confidence interval: 11.6-1234.7) after multivariable analysis. The incidence of PNI at the RSPV significantly increased in case of more distal positioning of the CB relative to the cardiac shadow. This simple and straightforward intra-procedural indicator might prone the operators to attempt occluding the RPSV more proximally in order to avoid PNI.

Phrenic nerve injury during ablation with the second-generation cryoballoon: analysis of the temperature drop behaviour in a large cohort of patients.

The present study sought to analyse the relationship between the temperature drop during the cryoenergy application and the occurrence of phrenic nerve injury (PNI) in a large cohort of patients having undergone second-generation cryoballoon ablation (CB-A). The first 550 consecutive patients having undergone CB-A for atrial fibrillation were enrolled. Attained temperatures at 20, 30, 40, and 60 s during cryoablation in the right-sided pulmonary veins (PVs) were collected. Diagnosis of PNI was made if reduced motility or paralysis of the hemidiaphragm was detected. The incidence of PNI in the study population was 7.3% (40/550); among them, only four (0.7%) did not resolve until discharge and one (0.2%) still persisted at 23 months. Patients with PNI exhibited significantly lower temperatures at 20, 30, and 40 s after the beginning of the cryoapplication in the right superior PV (RSPV) (P = 0.006, P = 0.003, and P = 0.003, respectively). The temperature drop expressed as Δ temperature/Δ time was also significantly higher in patients with PNI. Low temperature during the early phases of the freezing cycle (less than -38°C at 40 s) predicted PNI with a sensitivity of 80.5%, a specificity of 77%, and a negative predictive value of 97.9%. Among patients with a fast temperature drop during RSPV ablation, an RSPV diameter >23.55 × 17.95 mm significantly predicted PNI occurrence. The analysis of the temperature course within the first 40 s after the initiation of the freezing cycle showed that the temperature dropped significantly faster in patients with PNI during ablation in the RSPV.

The Incidence of Phrenic Nerve Injury During Pulmonary Vein Isolation Using the Second‐Generation 28 mm Cryoballoon

The second-generation cryoballoon (CB; Arctic Front Advance, Medtronic Inc., Minneapolis, MN, USA) has demonstrated greater procedural efficacy compared to the original CB. Whether increased efficacy translates into a higher incidence of phrenic nerve (PN) injury needs further evaluation. In patients with drug-refractory paroxysmal atrial fibrillation (AF) or short-standing persistent AF, pulmonary vein isolation (PVI) was performed using the 28 mm second-generation CB. During cryoenergy delivery along the septal PVs, continuous PN pacing was performed. The freeze cycle was aborted in case of weakening or loss of diaphragmatic contraction. A total of 115 patients (42 female, mean age 61 ± 11 years, mean LA-diameter 43 ± 6 mm) with a history of paroxysmal AF (93/115 patients [81%]) or short-standing persistent AF (22/115 patients [19%]) underwent CB-based PVI. A total 445 of 448 (99%) PVs were isolated successfully. PN palsy (PNP) occurred in 4 of 115 (3.5%) patients, while applying cryoenergy to the right superior PV. Despite prompt interruption of the freezing cycle, PN function failed to recover during the periprocedural phase. PN recovery was observed as late as 10 months postablation. Using the second-generation 28 mm CB, PNP occurred in 4 of 115 (3.5%) patients. While 1 of 4 PNP recovered 10 months after ablation, long-term outcome in the remaining 3 patients is currently unknown due to the rather short follow-up period.

Recordings of diaphragmatic electromyograms during cryoballoon ablation for atrial fibrillation accurately predict phrenic nerve injury

Cryoballoon ablation has been associated with a significant incidence of phrenic nerve injury (PNI). The purpose of this study was to evaluate whether recordings of diaphragmatic compound motor action potentials (CMAP) on a modified lead I during cryoballoon ablation can predict PNI. Cryoballoon ablation was performed in 109 patients with atrial fibrillation (AF). During ablation of the right-sided pulmonary veins, the phrenic nerve was paced from the superior vena cava. The right and left arm electrodes from a 12-lead ECG were positioned 5 cm above the xiphoid process and 16 cm along the right costal margin. The amplitude of CMAP was recorded on lead I during ablation. Cryoballoon was applied 424 times in 211 right-sided veins. PNI occurred in 7 (6.4%) patients. The average CMAP amplitude did not significantly change in patients without PNI from the initial average CMAP amplitude of 0.34 ± 0.18 mV to 0.32 ± 0.17 mV (P = .58). In patients who developed PNI, there was a significant decrease in the initial average CMAP amplitude during the ablation from 0.33 ± 0.14 mV to 0.09 ± 0.05 mV (P <.001). The maximal percent change in the average CMAP amplitude in patients with PNI was higher (70% ± 10%) than in patients without PNI (7.6% ± 7%; P <.001). In any patient without PNI, the CMAP amplitude did not decrease more than 35% from baseline. Recording of CMAP amplitude on a modified lead I is reliable and could be early and sensitive method for predicting PNI in patients undergoing cryoballoon ablation for AF.

Phrenic Nerve Injury after Radiofrequency Ablation of Lung Tumors: Retrospective Evaluation of the Incidence and Risk Factors

PurposeTo retrospectively investigate the incidence of and risk factors for phrenic nerve injury after radiofrequency (RF) ablation of lung tumors. Materials and MethodsThe study included 814 RF ablation procedures of lung tumors. To evaluate the development of phrenic nerve injury, chest radiographs obtained before and after the procedure were examined. Phrenic nerve injury was assumed to have developed if the diaphragmatic level was elevated after the procedure. To identify risk factors for phrenic nerve injury, multiple variables were compared between cases of phrenic nerve injury and randomly selected controls by using univariate analyses. Multivariate analysis was then performed to identify independent risk factors. ResultsEvaluation of phrenic nerve injury from chest radiographs was possible after 786 procedures. Evidence of phrenic nerve injury developed after 10 cases (1.3%). Univariate analysis revealed that larger tumor size (≥ 20 mm; P = .014), proximity of the phrenic nerve to the tumor (< 10 mm; P < .001), the use of larger electrodes (array diameter or noninsulated tip length ≥ 3 cm; P = .001), and higher maximum power applied during ablation (≥ 100 W; P < .001) were significantly associated with the development of phrenic nerve injury. Multivariate analysis demonstrated that the proximity of the phrenic nerve to the tumor (< 10 mm; P < .001) was a significant independent risk factor. ConclusionsThe incidence of phrenic nerve injury after RF ablation was 1.3%. The proximity of the phrenic nerve to the tumor was an independent risk factor for phrenic nerve injury.

The effect of left subclavian artery coverage on morbidity and mortality in patients undergoing endovascular thoracic aortic interventions: A systematic review and meta-analysis

Thoracic endografts (stent grafts) have emerged as a less invasive modality to treat various thoracic aortic lesions. The intentional coverage of the left subclavian artery (LSA) during the placement of these endografts is associated with several complications including stroke, spinal cord ischemia, and arm ischemia. In this review, we synthesize the available evidence regarding the complications associated with LSA coverage. We searched electronic databases (MEDLINE and EMBASE) from January 1990 through February 2008 for studies that included patients who received thoracic endografts and had intentional LSA coverage. Eligible studies had a control group that either received the endograft without LSA coverage or had primary revascularization prior to coverage. Two independent reviewers determined trial eligibility and extracted descriptive, methodological and outcome data from each eligible study. Meta-analyses estimated Peto odds ratio (OR) and 95% confidence intervals (CI) to describe the strength of association between coverage and complications; the I(2) statistic described the proportion of inconsistency of treatment effect among studies not due to chance. We found 51 eligible observational studies. LSA coverage was associated with significant increase in the risk of arm ischemia (OR 47.7; CI, 9.9-229.3; I(2) = 72%, 19 studies) and vertebrobasilar ischemia (OR 10.8; CI, 3.17-36.7; I(2) = 0%; eight studies); and nonsignificant increase in the risk of spinal cord ischemia (OR 2.69; CI, 0.75-9.68; I(2) = 40%; eight studies) and anterior circulation stroke (OR 2.58; CI, 0.82-8.09; I(2) = 64%, 13 studies). There were no significant associations between LSA coverage and death, myocardial infarction, or transient ischemic attacks. The incidence of phrenic nerve injury as a complication of primary revascularization was 4.40% (CI, 1.60%-12.20%). Data on perioperative infection were sparse and rarely reported. Very low quality evidence suggests that LSA coverage increases the risk of arm ischemia, vertebrobasilar ischemia, and possibly spinal cord ischemia and anterior circulation stroke.

Phrenic nerve injury associated with high free right internal mammary artery harvesting

Background The right phrenic nerve is at risk of injury during high mobilization of the right internal mammary artery (RIMA). The incidence and implications of this injury have not been previously defined. Methods Prospectively collected data on all patients who underwent RIMA harvesting between January 1995 and February 2002 were analyzed. Thirty-one patients with right phrenic nerve injury were identified and the medical charts reviewed. Phrenic nerve injury was diagnosed when a postoperative chest roentgenogram showed the right hemidiaphragm to be two or more intercostal spaces higher than the left, or transection of the nerve was seen intraoperatively. Investigations included fluoroscopy and spirometry in upright and supine positions. Diaphragm plication was offered for symptom control. Subsequent follow-up was undertaken to determine the incidence of spontaneous recovery of diaphragm function and the benefits of diaphragm plication. Results Seven hundred and eighty-three patients underwent high mobilization of the RIMA with proximal detachment for use as a free graft. Thirty-one patients with right hemidiaphragm dysfunction were identified in the postoperative period providing an injury incidence of 4% (confidence interval, 2.6% to 5.3%). Of these, 12 patients underwent diaphragm plication (4 early and 8 late), 14 patients achieved spontaneous recovery, and 5 patients were lost to follow-up. The supine to upright forced vital capacity ratios at the time of phrenic nerve dysfunction, after diaphragm plication, and after spontaneous recovery were 0.79, 0.90, and 0.96 respectively. Conclusions The incidence of phrenic nerve injury associated with high RIMA harvesting was 4% but spontaneous recovery may be anticipated in two thirds (14 of 22) of patients in whom the injury is identified postoperatively. High RIMA harvesting should be used with caution in patients with preoperative pulmonary dysfunction in whom phrenic nerve injury would be poorly tolerated.

Phrenic Nerve Function and Its Relationship to Atelectasis After Coronary Artery Bypass Surgery

Atelectasis following coronary artery bypass surgery (CAB) occurs in the majority of patients. To determine the importance of operative variables in the development of postoperative atelectasis and the incidence of phrenic nerve injury caused by topical cold cardioplegic solution, we studied 57 patients (53 male, four female) undergoing CAB. Their mean age, +/- SD, was 58 +/- 13 years. Transcutaneous stimulation was used to evaluate phrenic nerve function preoperatively and postoperatively in 52 patients. An unequivocal paresis of the phrenic nerve was documented in five patients. In an additional 27 patients, the amplitude of the compound diaphragm action potential was reduced postoperatively. However, methodologic limitations did not allow the conclusion that this was secondary to a phrenic axonal degeneration. Discriminant analysis of intraoperative variables showed more severe atelectasis with a larger number of grafts, with a longer operative and bypass time, when the pleural space was entered, when a right atrial drain and a cardiac insulating pad were not used, and with a lower body temperature. It is concluded that phrenic paresis may occur after CAB and topical cold cardioplegia, but that other factors must explain the atelectasis found in the majority of patients.