| Part 1. Researches on the effects of domestic AF ablation radiofrequency ablation deviceBackground Current common atrial radiofrequency ablation device still has the following disadvantages: 1. The power of the existing instrument is constant and non-adjustable. The same ablation strategies are used no matter which part of the organization is to be ablated. 2. One Atricure company’s Radiofrequency ablation clamp can only be single used within eight hours. Therefore, our center developed the independent intellectual property rights of atrial radiofrequency ablation devices and to verify it’s power range, suitable ablation times through in vitro experiment, and to verify electrical isolation rate by vivo experiments.Objective 1, To investigate the duration of ablation for atrial tissue with various thickness under different output of radiofrequency(RF)by domestic made RF ablation machine,and evaluate the accuracy of electrical resistance as the parameter of transmurality. 2, To analyze the transmurality by once or triple times of radiofrequency(RF) ablation delivered by domestic made RF ablation system.3, To analyze the electrical isolation of pulmonary veins by once or triple times of radiofrequency(RF) ablation delivered by domestic made RF ablation system.Methods 1, 20 cases of in vitro porcine heart were harvested fight after animals were sacrificed.The in vitro hearts were washed in normal saline twice at 4℃.Atrial tissue was harvested then.RF was delivered by a domestic made RF ablation system by 25,30,and 35 watts of output.Ablation lines were made in parallel with the distance of 5 mm in between on atrial tissue.The ablation was terminated after electrical resistance of the ablated tissue reached over 100 Ω.The duration of ablation,the tissue thickness,and the corresponding RF output were recorded.The ablation line Was excised for pathological section,transmurality was determined by Mason trichrome stain. 2, Atrial tissue stripes were prepared from 40 fresh porcine heart. They were allocated to <2, 2-4, and >4mm groups according to tissue thickness. Half of tissue from the same thickness group was randomly selected and ablated once by RF(Group A) while the other half was ablated triple times(Group B). Ablation time was recorded for each time of ablation. Thirty pigs were anaesthetized and had median sternotomy. 3, Fifteen pigs had their left pulmonary veins and left atrial appendages ablated once while their right pulmonary veins and atrial appendage ablated triple times(Group C). The other 15 pigs had right side leisions triply ablated while their left leision ablated once(Group D). Epicardial electrocardiograms were recorded on left atrium and pulmonary vein simultaneously before and after ablation. Isolated pulmonary veins were paced to see if the conduction block was complete. All tissue around the ablation line was send for Masson trichrome stain. Pathological transmurality were check by microscope.Results 1, 350 ablation lines were made successfully.Under the same RF output,the ablation duration was longer in the group of atrial tissue with the thickness between 4 and 6mm,and thicker than 6 mm as compared with the duration of atrial tissue less than 2 mm in thickness[(12.4±0.9)s vs(24.3+0.3)s,P=O.042,(12.4+0.9)S vs(35.9+0.3)S,P=-O.001].With the same tissue thickness,the duration of ablation was significantly different between groups of 25 W and 35 W output[(28.9+0.5)s vs(16.9+0.5)S,p=0.010].The duration of ablation was positively correlated to the thickness of atrial tissue.The pathological transmurality varied from 0 to 60%.It increased with the higher output.and decreased with the thicker atrial tissue. 2, Pathological transmurality was achieved in 51.3% and 98.3% atrial tissue in Group A and B respectively. In group A, ablation time was significantly different between groups of different tissue thickness. Time for 2nd and 3rd ablation became significantly shorter as compared with first-time ablation. 3, Electrical isolation of pulmonary veins were recorded in 72.2% by once ablation and 100% by triple ablations.Conclusions 1, The duration of ablation is determined by the thickness of atrial tissue and the RF output.The pathological transmurality is relatively low with single ablation.30 and 35 W are optional RF output,considering thesafety of ablation,reasonable ablation duration and pathological transmurality. 2, The use of domestic bipolar radiofrequency ablation device triple ablations could significantly improve the pathological tissue ablation rate through. The ablation time prolonged with tissue thickness increased, decreased with the times of ablation. The thickness of >5mm in atrial tissue after triple ablations may still be impervious wall. 3, RF ablation for triple ablation could significantly improve transmularity and electrical isolation of pulmonary veins as compared with single ablation.Part 2. The effect of minimally invasive surgical ablation of lone atrial fibrillation to functional mitral or tricuspid regurgitationBackground The minimally invasive surgical ablation with small trauma, high success rate of operation had become the hot spot for the treatment of isolated atrial fibrillation. Previous research focused on the research of the trauma and success rate. Changes in left atrial diameter, left ventricular ejection fraction in patients accepted minimally invasive surgery and preoperative mild to moderate functional mitral or tricuspid regurgitation are often ignored.Objective 1,We followed up the preoperative and the postoperative data by echocardiography, to estimate the changes of left atrial size and left ventricular ejection fraction of patients who accepted minimally invasive surgical radiofrequency ablation. 2, We followed up the preoperative and the postoperative data by echocardiography, to estimate the changes of functional mitral or tricuspid regurgitation.Methods Statistics since September 2010 until December 2013, totally 201 cases affected the minimally invasive surgical ablation in Xinhua Hospital Affiliated to Shanghai Jiaotong University. Among them, 98 patients were with paroxysmal atrial fibrillation patients, 103 patients were with persistent atrial fibrillation. We statistic the patients’ clinical foundation before surgery, using transthoracic echocardiography to measure left atrial diameter(LAD), left ventricular ejection fraction(LVEF), left ventricular end-diastolic diameter(LVDd), mitral regurgitation( MR), tricuspid regurgitation(TR). All patients were followed up by telephone inquiries or outpatient visits. Patients take multi-lead ECG or 24-hour Holter, after 1 month, 3 months, 6 months,12 months, 24 months, 36 months of surgery, and take transthoracic echocardiography after 3 months, 6 months, 12 months, 24 months, 36 months of surgery, to assess the patient’s heart rhythm and heart rate, and transthoracic echocardiography situation. Compared the preoperative and the postoperative data in patients with left atrial diameter(LAD), left ventricular ejection fraction(LVEF), left ventricular end-diastolic diameter(LVDd), mitral regurgitation(MR), tricuspid regurgitation(TR) situation.Results All patients with an average follow-up time was 25.2 ± 7.0 months, 91.5%(184/201) of patients with atrial fibrillation maintained sinus rhythm during follow-up, sinus rhythm in patients with paroxysmal atrial fibrillation was 92.9%(91/98), persistence and long-range sinus rhythm in patients with atrial fibrillation was 90.3%(93/103). In this study, 201 patients before surgery mean left atrial diameter was 41.55 ± 5.41 mm, the mean postoperative left atrial diameter was 38.48 ± 5.13 mm, left atrial diameter significantly reduced(P = 0.001). Description of minimally invasive surgical radiofrequency ablation can improve the patients’ left atrial remodeling. Comparing the preoperative left atrial diameter of patients who maintain sinus(n = 184) and patients with recurrent atrial fibrillation(n = 17), we find the former group of patients without recurrence mean left atrial diameter was 41.37 ± 5.27 mm, recurrent group of patients mean left atrial diameter was 43.50 ± 6.56 mm, there is no significant difference between the two groups(P = 0.119). No relapse patients were followed up for an average of left atrial diameter was 38.05 ± 4.82 mm, compared with preoperative significant reduction(P = 0.001); and the mean left atrial diameter recurrent postoperative followed up was 43.08 ± 6.17 mm, with no preoperative significant difference(P = 0.47); the recurrence group there was a significant difference(P = 0.001) with no recurrence postoperative left atrial diameter. The mean preoperative left atrial diameter in patients with paroxysmal atrial fibrillation was 38.38 ± 4.19 mm, mean preoperative left atrial diameter in patients with persistent atrial fibrillation was 44.56 ± 4.68 mm, the former group of patients with persistent AF compared with paroxysmal group left atrial diameter significantly increased(P = 0.001). The mean left atrial diameter of paroxysmal atrial fibrillation group was 35.69 ± 4.33 mm, while the persistent AF group was 41.12 ± 4.38 mm, both group had significant decrease(P = 0.001) compared with the data before surgery. The above results are consistent with existing research findings. It is noteworthy that patients with mean left atrial diameter reducing persistent AF group(3.43 ± 3.00mm), compared with paroxysmal AF group(2.69 ± 2.88mm) was significantly decreased(P = 0.045) Left ventricular ejection fraction of postoperative data(62.97 ± 6.70,%) were significantly different(P = 0.001) compared with preoperative data(58.32 ± 6.98,%). Left ventricular ejection fraction of patients without recurrence improved significantly(P = 0.001), whereas there was no significant difference in relapse group(P = 0.24). Data of mitral regurgitation of patients without recurrence(1.93 ± 1.65 ml) was significantly reduced(P = 0.001) compared with preoperative data(3.51 ± 1.74 ml), while the recurrent group had no significant changes(P = 0.17). Data of tricuspid regurgitation of patients without recurrence(4.17 ± 2.81 ml) was significantly reduced(P = 0.001) compared with preoperative data(6.54 ± 3.50 ml), while the recurrent group had no significant changes(P = 0.20).Conclusions Minimally invasive surgical radiofrequency ablation can significantly improve the patient’s atrial remodeling, improve left ventricular ejection fraction and can effectively improve the functional mitral or tricuspid regurgitation. |
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