Outcome of concomitantCox-maze III procedure using an argon-based cryosurgical system: a single-center experience with 250 patients

Randomized Trial of Concomitant Maze Procedure Using Nitrous Oxide- Versus Argon-Based Cryoablation

BACKGROUND

Currently, two types of cryoprobes are available: nitrous oxide (N₂O)-based and argon gas-based. However, few studies have compared the outcomes obtained with these two cryoprobe types. The aim of this study was to compare the early outcomes of a concomitant maze procedure using N₂O-based cryoablation (the N₂O group) versus argon gas-based cryoablation (the argon group) in patients with persistent atrial fibrillation (AF).

METHODS

This study was a single-center, prospective, randomized controlled clinical trial. Sixty patients were randomly assigned to receive a concomitant maze procedure using N₂O-based cryoablation (n = 30) or argon gas-based cryoablation (n = 30) for persistent AF. Patients were followed up at 3, 6, and 12 months by electrocardiography, 24-hour Holter monitoring, and transthoracic echocardiography.

RESULTS

No important intergroup differences were observed in terms of preoperative variables, morbidity, or mortality. During 1 year of follow-up, normal sinus rhythm was maintained in 26 patients in the N₂O group and 26 patients in the argon group (86.7% versus 86.7%, p = 1.000). Freedom from atrial arrhythmia events at 12 months was observed in 84.5% ± 4.7% without intergroup differences. Early AF episode before discharge was correlated with atrial arrhythmia events during follow-up (hazard ratio 7.89, 95% confidence interval: 1.75 to 35, p = 0.007). The N₂O group showed earlier recovery of left atrial activity compared with the argon group (p = 0.043); however, this difference disappeared after 6 months.

CONCLUSIONS

Both procedures have similar 1-year sinus rhythm maintenance rates. Left atrial contractile activity tends to return earlier in the N₂O group.

Valve surgery in combination with cryoablation in the treatment of atrial fibrillation

Objective:

To investigate the effectiveness and safety of valve surgery in combination with cryoablation in the treatment of atrial fibrillation.

Methods:

Fifty patients who needed to undergo valve surgery because of heart valve disease and sixty-five patients who needed to undergo valve surgery in combination with cryoablation were selected as the research subjects. The perioperative technical characteristics, postoperative curative effect and complications were compared between the two different treatment modalities in our hospital between October 2013 and November 2015.

Results:

No significant differences were observed between the two groups in valve surgery mode, valve type and postoperative length of hospital stay (P>0.05), but the duration of extracorporeal bypass and aorta occlusion of the observation group was longer than that of the control group (P<0.05). The 3-month, 6-month and one-year atrial fibrillation cardioversion rates of patients in the observation group were superior to those of the control group, and the differences were notable (P<0.05). The improvement of left atrial diameter of the observation group was also superior to that of the control group (P<0.05). The incidence of postoperative complications of the two groups had no significant difference (P>0.05).

Conclusion:

Valve surgery in combination with cryoablation has favorable short-term clinical effect in the treatment of heart valve disease in combination with atrial fibrillation, which is worth promotion.

Early Results of the Modified Right Atrial Lesion Set for the Cox-Cryomaze Procedure

Objective

The standard right atrial lesion (RAL) set, as originally outlined in the Cox-Maze III procedure, can be technically challenging when using a cryoprobe to create the lesions. We report our initial experience with an alternative set of RALs for the surgical treatment of atrial fibrillation (AF).

Methods

Between September 2011 and January 2015, a total of 112 patients underwent a CryoMaze procedure with biatrial lesions using argon-based cryoablation (cryoprobe temperature, −160°C). Although the standard left atrial lesion set was used, the RAL pattern was modified in this cohort of patients. The intracaval superior vena cava-inferior vena cava lesion was performed as in the pattern described for the standard Cox-Maze III procedure. In addition, a horizontal atriotomy incision (the “T” lesion) in the mid free wall of the right atrium was based roughly in the midintercaval line and extended medially as a linear cryolesion to the lateral tricuspid annulus at the so-called 2-o'clock position as in the Cox-Maze III lesion pattern. Ordinarily, a linear cryolesion would be placed from the tip of the right atrial appendage (RAA) to the anterior tricuspid annulus at the so-called 10-o'clock position to prevent macro re-entry around the base of the RA appendage. Our modification consisted of, instead, a linear cryolesion directed perpendicularly from the mid portion of the atriotomy (T lesion) to the tip of the RA appendage, which simply interrupted RAA re-entry at another point.

Results

The mean ± standard deviation age was 72.7 ± 10.6 years, 56.3% were males, and 63.1% had long-standing persistent AF. There were three operative deaths (2.6% with an observed over expected of 0.58), all in the concomitant procedures with associated cardiac disease. Overall follow-up was 91.3%. Freedom from AF at discharge, 1-, 3-, 6-, 12-, 24-month, and last follow-up [16.1 ±11.3 months (range, 0.4–43 months)], was 100%, 76.3%, 84.2%, 98.3%, 89.5%, 89.2%, and 90.5%, respectively. Similarly, freedom from antiarrhythmic drugs was 74% and 81%, whereas freedom from anticoagulants was 72% and 78% at 12 and 24 months, respectively.

Conclusions

These results suggest the modified RAL set to be an effective alternative to the traditional RALs of Cox-Maze III. By substituting this lateral RAA lesion for the more technically difficult medial lesion, the procedure becomes easier to perform and favorably impacts operative time while achieving comparable results in reducing AF burden.

Efficacy of Cox Maze IV Procedure Using Argon-Based Cryoablation: A Comparative Study with N2O-Based Cryoablation

BACKGROUND

We compared the mid-term results of the Cox maze IV procedure using argon-based cryoablation with a procedure using N2O-based cryoablation.

METHODS

From May 2006 to June 2012, 138 patients (mean age, 58.2±11.0 years) underwent the Cox maze IV procedure. Eighty-five patients underwent the maze procedure using an N2O-based cryoprobe (group N), and 53 patients underwent the maze procedure using an argon-based cryoprobe (group A). Bipolar radiofrequency ablation was concomitantly used in 131 patients. The presence of atrial fibrillation immediately, 6 months, 1 year, and 2 years after surgery was compared.

RESULTS

Early mortality occurred in 6 patients (4.3%). There were no differences in early mortality or postoperative complications between the two groups. Nineteen of 115 patients (16.5%) remained in atrial fibrillation at postoperative 12 months (14 of 80 patients (17.5%) in group N and 5 of 35 patients (14.3%) in group A, p=0.669). There were no differences in the number of patients who remained in atrial fibrillation at any of the time periods except in the immediate postoperative period. A multivariable analysis revealed that the energy source of cryoablation was not associated with the presence of atrial fibrillation at 1 year (p=0.862) and that a fine F wave (<0.1 mV) was the only risk factor predicting the presence of atrial fibrillation at 1 year (p<0.001, odds ratio=20.287).

CONCLUSION

The Cox maze IV procedure using an argon-based cryoprobe was safe and effective compared with the maze procedure using an N2O-based cryoprobe in terms of operative outcomes and the restoration of sinus rhythm for up to 2 years after surgery.

Outcome of concomitant cox maze procedure with narrow mazes and left atrial volume reduction

Background

To improve sinus rhythm conversion, the Cox maze III procedure with narrow mazes (width: ≤3.0 cm) was performed in combination with left atrial volume reduction.

Methods

From October 2007 to April 2013, 87 patients with atrial fibrillation (paroxysmal in 3, persistent in 14, and permanent in 70) underwent the Cox maze procedure concomitant with another cardiac procedure. They were followed-up with serial electrocardiographic and echocardiographic studies. We used 24-hour Holter monitoring tests to evaluate postoperatively symptomatic patients.

Results

At the mean follow-up time of 36.4 months, 81 patients (94.2%) had sinus rhythm and two were on anti-arrhythmic medication (one on a beta-blocker and the other on amiodarone). Five patients (5.8%) with postoperative recurrent and persistent atrial fibrillation never experienced sinus rhythm conversion; however, they did not require any medication for rate control. On postoperative echocardiography, the left atrial A waves were more frequently observed after concomitant mitral valve repair than after concomitant mitral valve replacement (82.4% vs. 40.4%, respectively; p<0.001).

Conclusion

For the Cox maze procedure, narrow mazes and atrial volume reduction resulted in excellent sinus rhythm conversion without the preventive use of anti-arrhythmic drugs, and they did not affect the presence of the left atrial A waves on echocardiography.

A novel animal model of osteonecrosis of the femoral head induced using a magnetic resonance imaging-guided argon-helium cryotherapy system

The aim of the present study was to establish a novel animal model of osteonecrosis of the femoral head (ONFH) using a magnetic resonance imaging (MRI)-guided argon-helium cryotherapy system. A total of 48 rabbits were used to generate the ONFH models. In group I, the left femoral head of the rabbits received two cycles of argon-helium freezing-thawing under MRI guidance, while in group II, the right femoral head of each rabbit received only one cycle of argon-helium freezing-thawing. X-ray and histological examinations were performed. The percentages of lacunae in the femoral heads of group I at weeks 4, 8 and 12 following surgery (49.75±3.17, 62.06±4.12 and 48.25±2.76%, respectively) were higher than those in group II (39.13±4.48, 50.69±3.84 and 37.50±3.86%, respectively). In addition, the percentage of empty lacunae in group I was 62.06% at week 8 following surgery. Therefore, an animal model of ONFH was successfully established using an argon-helium cryotherapy system. The percentage of empty lacunae in group I was higher than that in group II at weeks 4, 8 and 12 after surgery.