Tissue temperatures and lesion size during irrigated tip catheter radiofrequency ablation: an in vitro comparison of temperature-controlled irrigated tip ablation, power-controlled irrigated tip ablation, and standard temperature-controlled ablation

The limited success rate of radiofrequency catheter ablation in patients with ventricular tachycardias related to structural heart disease may be increased by enlarging the lesion size. Irrigated tip catheter ablation is a new method for enlarging the size of the lesion. It was introduced in the power-controlled mode with high power and high infusion rate, and is associated with an increased risk of crater formation, which is related to high tissue temperatures. The present study explored the tissue temperatures during temperature-controlled irrigated tip ablation, comparing it with standard temperature-controlled ablation and power-controlled irrigated tip ablation. In vitro strips of porcine left ventricular myocardium were ablated. Temperature-controlled irrigated tip ablation at target temperatures 60 degrees C, 70 degrees C, and 80 degrees C with infusion of 1 mL saline/min were compared with standard temperature-controlled ablation at 70 degrees C and power-controlled irrigated tip ablation at 40 W, and infusion of 20 mL/min. Lesion size and tissue temperatures were significantly higher during all modes of irrigated tip ablation compared with standard temperature-controlled ablation (P < 0.05). Lesion volume correlated positively with tissue temperature (r = 0.87). The maximum recorded tissue temperature was always 1 mm from the ablation electrode and was 67 +/- 4 degrees C for standard ablation and 93 +/- 6 degrees C, 99 +/- 6 degrees C, and 115 +/- 13 degrees C for temperature-controlled irrigated tip ablation at 60 degrees C, 70 degrees C, and 80 degrees C, respectively, and 112 +/- 12 degrees C for power-controlled irrigated tip ablation, which for irrigated tip ablation was significantly higher than tip temperature (P < 0.0001). Crater formation only occurred at tissue temperatures > 100 degrees C. We conclude that irrigated tip catheter ablation increases lesion size and tissue temperatures compared with standard ablation in the temperature-controlled mode at the same or higher target temperatures and in the power-controlled mode. Furthermore, tissue temperature and delivered power are the best indicators of lesion volume during temperature-controlled ablation.     

Generating radiofrequency ablation lesions using magnetically coupled bipolar catheters

Background: Transmural lesions are difficult to produce in myocardial regions with thick walls, such as the left ventricle (LV), using conventional radiofrequency (RF) ablation catheters. This study was performed to evaluate the efficacy of magnetically coupled bipolar catheters and compare the performance with conventional unipolar and bipolar RF ablation catheters. Methods and Results: Neodymium magnets assembled in ablation catheters were used to facilitate tissue contact in a bipolar RF ablation system. In vitro sheets of porcine skeletal muscle, with 10‐mm thickness, were ablated with a 4‐mm‐tip unipolar RF ablation catheter (UA), a bipolar ablation system (BA) using a pair of 4‐mm‐tip catheters, and a magnetically coupled bipolar system (MB). The RF generator setting was 50 W and 90°C. RF energy was delivered for 30 or 60 seconds and five lesions were created in each ablation condition. The bottom side of the skeletal‐muscle sheet was exposed to saline at 37°C and a flow of 5.6 L/min, mimicking the LV endocardial surface. The top side was exposed to air, mimicking the epicardial surface. In the 60‐second ablation cases, the transmuralities were 0%, 0%, and 40% (UA, BA, and MB, respectively). The volumes of the lesions were 61.5 ± 8.5, 224.3 ± 51.8, and 359.3 ± 93.8 mm³ (UA, BA, and MB, respectively). Conclusions: The magnetically coupled bipolar RF ablation system created transmural lesions more efficiently than the conventional ablation system, primarily due to higher RF current density and stronger tissue contact. This prototype method could be applied to the development of novel ablation devices for thick areas of tissue. (PACE 2011; 34:934–938)     

Temperature response following nontraumatic low power radiofrequency application

A marker for the efficiency of heating would be helpful in radiofrequency ablation of tachyarrhythmias. We hypothesized that changes of the catheter tip temperature during nontraumatic, very low power radiofrequency exposure would correlate with the temperature achieved during radiofrequency ablation, and therefore, could be used as a marker for heating efficiency. In 71 ablation attempts for drug refractory supraventricular tachycardias, the catheter tip temperature response to a 1-W-5-second test pulse was measured. Subsequently at the same site, radiofrequency current was delivered with a target temperature of 70 degrees C and a power limit of 50 W. The test pulse, with a measured power level of 1.62 +/- 0.28 W, resulted in a heating efficiency of 0.78 +/- 0.60 degree C/W. During ablation, the achieved tip temperature was 52.9 +/- 7.5 degrees C, requiring a power output of 40.7 +/- 10.9 W. The heating efficiency was 0.57 +/- 0.74 degree C/W. The correlation between heating efficiency at low power and during radiofrequency ablation was linear with a correlation coefficient of 0.88. Regression analysis demonstrated that a heating efficiency above 1 degree C/W predicts a mean ablation temperature above 50 degrees C with more than 95% confidence interval. The temperature response to a very low power radiofrequency application correlates with the temperature rise achieved during radiofrequency ablation. It is suggested that delivery of low power radiofrequency current could be used to determine and monitor efficiency of heating during catheter mapping and ablation procedures.     

Radiofrequency catheter ablation with the split-tip electrode in the temperature-controlled mode

The 7 Fr "split-tip electrode" (2.5-mm tip electrode divided longitudinally into four electrodes with an adjacent 2-mm ring electrode) improves mapping resolution due to its small recording electrodes and narrow interelectrode distances (0.1 mm). The purpose of this study was to examine the temperature-controlled ablation properties of this electrode. In seven anesthetized dogs, the thigh muscles were exposed and superfused with canine blood. A split-tip catheter electrode (with a thermocouple in each of the five electrodes) and a conventional 4-mm catheter electrode were positioned at constant pressure perpendicular or parallel to the surface of the thigh muscle. Impedance measured between each split electrode and a skin patch correlated with the degree of contact with blood and tissue. In the parallel catheter to tissue orientation, split electrodes not in contact with tissue had a low impedance (mean 210-224 ohms), and the split electrode almost entirely in contact with tissue had the highest impedance (380 +/- 56 ohms). In the perpendicular catheter to tissue orientation all split electrodes had a similar impedance (mean 279-286 ohms). A total of 75 radiofrequency (RF) lesions were produced in the temperature-controlled mode with the 4-mm electrode (target 60 degrees C) or the split-tip electrode (power limited by the hottest electrode reaching 70 degrees C) with current delivered to all five electrodes simultaneously, or only to electrodes in contact with tissue. Lesion depth was not significantly different between electrodes in the parallel orientation (5.2 +/- 0.9 vs 5.1 +/- 1.4 vs 5.3 +/- 1.1 mm), but significantly deeper with the conventional 4-mm tip electrode in the perpendicular orientation (6.7 +/- 1.2 vs 5.3 +/- 1.3 vs 5.6 +/- 0.9 mm, P < 0.05). This was due to higher power delivered to the conventional 4-mm electrode (27 +/- 9 vs 17 +/- 7 vs 15 +/- 7 W, P < 0.05) because convective cooling by the blood flow was less effective for the split-tip electrode due to a reduced heat conduction across the interelectrode space from the hottest electrode to cooler areas of the group of five electrodes (mean temperature difference between the hottest split electrodes and the ring electrode: 24 degrees C). Electrode cooling or heat conduction was not effected by the elimination of current delivery to non-contact electrodes. Steam pops occurred in 36% of applications with the conventional 4-mm electrode in the perpendicular orientation but never with the split-tip electrode in spite of the higher target temperature. Measurement of impedance from the split electrodes allow the determination of electrode tissue contact and RF lesions produced with the split-tip electrode in the temperature-controlled mode using a target of 70 degrees C were of reasonable size and not associated with steam pops.     

心房颤动导管消融的地位和进展

心房颤动(房颤)是临床常见的心律失常之一,最大风险是血栓栓塞,常见是脑卒中。随着人口的老龄化,房颤人数持续增加,治疗问题也逐渐成为人们关注重点。房颤导管消融是其重要治疗方法之一,可明显改善房颤患者预后。且随着技术发展,消融方法也日趋成熟,故导管消融术治疗房颤地位正在逐步提升。但消融方法尚无固定术式,发生机制尚未完全明确,尤其对于持续房颤。因此房颤消融术仍存在一些问题有待进一步探索。     

Primary radiofrequency ablation for incessant idiopathic ventricular tachycardia

Fascicular VT and RVOT tachycardia are sometimes difficult to induce by programmed electrical stimulation (PES), despite pharmacologic provocation. In such instances, catheter mapping is hampered and efficacy of catheter ablation is difficult to judge. The study included nine patients who presented with incessant idiopathic VT and were directly taken to the electrophysiological laboratory for RF ablation. During the same period, elective ablation was performed on 108 patients with idiopathic VT. The success rate, procedural and fluoroscopy times number of energies, and the peak temperature were evaluated and compared. Of the nine patients, seven had incessant fascicular VT and two had RVOT tachycardia. The mean VT cycle length was 356 +/- 32 ms and the earliest endocardial activation time during VT was 23.6 +/- 6 ms relative to surface QRS complexes. A fascicular potential was not seen in three of the seven patients with fascicular VT. The mean procedural time was 71 +/- 32 minutes and 144 +/- 40 minutes (P = 0.023) while the fluoroscopy time was 14.6 +/- 4.6 minutes and 30 +/- 16 minutes (P < 0.001), respectively, in the primary ablation and elective groups. The total number of RF energies delivered was 2.0 +/- 1.3 versus 7.4 +/- 5.6 (P = 0.07), respectively. The significantly increased procedural time during elective ablation was largely due to time spent in fascicular VT induction. All patients in the primary ablation group were successfully ablated and none had a recurrence. Primary ablation is a safe and effective option in patients with incessant idiopathic VT. Moreover, in fascicular VT, it is superior to elective ablation in terms of success, fluoroscopy and procedural times.     

射频消融术后心肌肌钙蛋白的变化

目的　观察射频消融术患者术前、术后血清心肌肌钙蛋白I(cTnI)、肌酸磷酸激酶同工酶 (CK MB)及心功能的变化 ,评价cTnI、CK MB在诊断心肌微小损伤中的灵敏性 ,探讨心肌损伤程度与消融因素的相关性。方法　选择行射频消融术 (RFCA)的阵发性室上性心动过速 (PSVT)患者 80例。每例患者均于术前及术后测定血清cTnI、CK MB水平及超声心动图。结果　术后 4～ 2 4小时cTnI及CK MB较术前明显增高 ,cTnI及CK MB升高倍数与消融能量无线性关系 (r =0 .2 0 ,P >0 .0 5 ;r =0 .2 6 ,P >0 .0 5 ) ,与消融时间、消融次数呈正相关 (r =0 .5 6 ,r =0 .4 2,P均 <0 .0 5 ;r =0 .37,r =0 .4 8,P均 <0 .0 5 )。心室侧消融术后 4～ 2 4小时cTnI的升高倍数和术后 4～ 2 4小时数值均显著高于心房侧消融 (P <0 .0 5 )。旁道组术后cTnI和CK MB升高倍数高于双径路组。RFCA术后左室射血分数 (LVEF)、左室短轴缩短率 (LVFS)、二尖瓣舒张早期最大流速 (E)及二尖瓣舒张晚期最大流速 (A)的比值 (E/A)与术前比较差异无统计学意义 (P >0 .0 5 )。结论　RFCA所造成的心肌损伤为小范围的损伤 ,不影响心脏的整体功能。检测这种微小损伤 ,cTnI的灵敏度较CK MB高。这种损伤与放电时间、放电次数、消融部位有关 ,而与放电能量无关。     

射频消融术后尿潴留患者的护理

分析86例射频消融术后患者出现尿潴留的不同原因，包括不习惯床上排尿、精神因素、疼痛等。护理对策包括：减少卧床时间，心理护理，变换体位，物理诱导，术后多饮水等，结果81例患者排尿成功，只有5例(5．8％)男性前列腺肥大患者需要导尿。     

The results of radiofrequency catheter ablation of supraventricular tachycardia in children

BACKGROUNDS: Radiofrequency (RF) catheter ablation represents a major advance in the management of children with cardiac arrhythmias and has rapidly become the standard of care for the first-ling therapy of supraventricular tachycardias (SVTs). The purpose of this study was to investigate the results of the RF catheter ablation of SVTs in pediatric patients. METHODS: From December 1989 to August 2005, a total of 228 pediatric patients (age: 9 +/- 7 years, range: 5-18 years; male:female = 117:111) with clinically documented SVT underwent an electrophysiologic study and RF catheter ablation at our institution. RESULTS: The arrhythmias included atrioventricular reentrant tachycardia (AVRT; n = 140, 61%), atrioventricular nodal reentrant tachycardia (AVNRT; n = 66, 29%), atrial tachycardia (AT; n = 11, 5%), and atrial flutter (AFL; n = 11, 5%). The success rate of the RF catheter ablation was 92% for AVRT, 97% for AVNRT, 82% for AT, and 91% for AFL, respectively. Procedure-related complications were infrequent (8.7%; major complications: high grade AV block (2/231, 0.9%); minor complications: first degree AV block (6/231, 2.6%), reversible brachial plexus injury (2/231, 0.9%), and local hematomas or bruises (10/231, 4.3%)). The recurrence rate was 4.7% (10/212) during a follow-up period of 86 +/- 38 months (0.5-185 months). CONCLUSIONS: The RF catheter ablation was a safe and effective method to manage children with paroxysmal and incessant tachycardia. The substrates of the arrhythmias differed between the pediatric and adult patients. However, the success rate of the ablation, complications, and recurrence during childhood were similar to those of adults.     

High incidence of thrombus formation without impedance rise during radiofrequency ablation using electrode temperature control

The authors hypothesized that during RF ablation, the electrode to tissue interface temperature may significantly exceed electrode temperature in the presence of cooling blood flow and produce thrombus. In 12 anesthetized dogs, the skin over the thigh muscle was incised and raised to form a cradle that was superfused with heparinized canine blood (ACT > 350 s) at 37 degrees C. A 7 Fr, 4-mm or 8-mm ablation electrode containing a thermocouple was held perpendicular to the thigh muscle at 10-g contact weight. Interface temperature was measured at opposite sides of the electrode using tiny optical probes. RF applications (n = 157) were delivered at an electrode temperature of 45 degrees C, 55 degrees C, 65 degrees C, and 75 degrees C for 60 seconds, with or without pulsatile blood flow (150 mL/min). Without blood flow, the interface temperature was similar to the electrode temperature. With blood flow, the interface temperature (side opposite blood flow) was up to 36 degrees C and 57 degrees C higher than the electrode temperature using the 4- and 8-mm electrodes, respectively. After each RF, the cradle was emptied and the electrode and interface were examined. Thrombus developed without impedance rise at an interface temperature as low as 73 degrees C without blood flow and 80 degrees C with blood flow (11/16 RFs at 65 degrees C electrode temperature using 4 mm and 13/13 RFs at an electrode temperature of 55 degrees C using an 8-mm electrode with blood flow). With blood flow, interface temperature markedly exceeded the electrode temperature and the difference was greater with an 8-mm electrode (due to greater electrode cooling). In the presence of blood flow, thrombus occurred without an impedance rise at an electrode temperature as low as 65 degrees C with a 4-mm electrode and 55 degrees C with an 8-mm electrode.     

Popping Phenomena in Temperature‐Controlled Radiofrequency Ablation: When and Why Do They Occur?

During temperature-controlled radiofrequency (RF) ablation a popping sound sometimes occurs. This popping phenomenon is known to be associated with unwanted effects like blood boiling, endocardial rupture, catheter dislocation, and impedance rise. The present in vitro study determined the influence of cooling, electrode contact, and tip temperature on the occurrence of popping phenomena. Pieces of porcine ventricle were immersed in a bath of saline solution at 37 degrees C. Forty-two RF ablations were performed with different electrode-tissue contact forces (i.e., 0.0-0.44 N) in a temperature-controlled mode (70 degrees C setpoint, 30 s, 50 W maximum power output, 4-mm tip, thermocouple). Half of the 42 ablations were performed with fluid flow (0.1 m/s, group I), the other half without flow (group II). In group I, mean tip temperature and power were 55.6 +/- 8.5 degrees C and 36.2 +/- 13.8 W, resulting in a lesion volume of 121 +/- 57 mm3. In group II, the respective values were 67.3 +/- 1.5 degrees C and 9.9 +/- 5.2 W resulting in a volume of 42 +/- 18 mm3. The differences between groups were statistically significant. Overall, ten popping phenomena occurred in group I and none in group II. Pops occurred significantly more often when the contact force was < 0.1 N (8/10) and the tip temperature was < 60 degrees C (8/10). Two endocardial ruptures occurred, both were associated with a popping phenomenon. Using temperature control, the probability of pops is significantly higher when the ablation electrode and the endocardial tissue surface are exposed to fluid flow and the electrode-tissue contact is poor. Under these conditions the tissue temperature can be much higher than the temperature measured at the tip electrode and can potentially reach 100 degrees C causing intramyocardial steam formation and a popping phenomenon.     

Effect of inter-electrode distance on bipolar intramural radiofrequency ablation

Objectives: We aimed at evaluating bipolar radiofrequency ablation by correlating inter-electrode distance (ILD) with lesion dimensions and continuity.
Background: Previous reports indicated that bipolar radiofrequency (RF) current applied to two adjacent sites in vitro, synergistically increased lesion sizes greater than that observed for unipolar RF current delivery using the same electrodes.
Methods: Ablations were performed intramurally to ensure that each electrode surface (radius = 0.4 mm, area = 3.52 mm²) provided consistent contact with the myocardium. Ninety-six ablations were performed in four greyhounds using bipolar ablation needles with ILDs of 1, 2, 3, and 4 mm. An epicardial approach was used to ensure accurate positioning of the needles within the myocardium. Lesions were created using temperature-controlled RF delivery for a duration of 60 seconds to achieve 90°C at the electrode proximal to the needle base. Lesion dimensions were determined histologically.
Results: Increasing the ILD, decreased lesion width (P = 0.003) but increased lesion depth (P = 0.001). Lesions remained continuous with ILDs of 1–3 mm but became discontinuous at 4 mm. Energy requirements during ablation increased with increasing ILDs.
Conclusion: Using the above parameters (electrode radius, RF power delivery, time) during bipolar ablation, lesion continuity was critically dependent on the ILD. The maximum ILD threshold to create contiguous overlapping lesions was 3 mm. Lesions of greater width were created using shorter ILDs. Clinically, greater control over lesion dimensions can be obtained by manipulating the ILD distance.     

Assessment of radiofrequency ablation effect from unipolar pacing threshold

Methods for determining if an ablation lesion has been created by RF current application are limited, but needed. This study sought to determine if a change in pacing threshold at the ablation site might be used to assess creation of an ablation lesion. Peak-to-peak amplitude of the bipolar electrogram (EGM) and the unipolar pacing threshold were determined before and after creation of RF lesions using irrigated tip (63 lesions in 11 patients) or conventional ablation catheters (33 lesions in 9 patients) in infarct scars for ablation of ventricular tachycardia. The threshold was measured during continuous pacing at a cycle length of 600 ms by a decrementing output current at a pulse width of 2 ms. The unipolar pacing threshold increased by 254 +/- 248% (from 5.7 +/- 3.5 to 15.1 +/- 6.7 mA, P<0.001) after irrigated tip ablation and by 155 +/- 144% (from 5.9 +/- 3.4 to 12.3 +/- 5.7 mA, P<0.001) after conventional ablation (P<0.05 for irrigated tip vs conventional). EGM amplitude decreased by 17 +/- 27% (from 0.39 +/- 0.32 to 0.30 +/- 0.21 mV) after irrigated tip ablation and by 16 +/- 24%(from 0.48 +/- 0.27 to 0.41 +/- 0.20 mV) after conventional ablation (irrigated tip vs conventional, P=NS). There was no correlation between the change in bipolar EGM amplitude and the pacing threshold. An increase in unipolar pacing threshold is a marker of lesion creation. In regions of infarction, the relative change in threshold produced by ablation is substantially larger than the change in bipolar electrogram amplitude. The greater increase in pacing threshold after irrigated tip ablation compared to conventional ablation suggests that the magnitude of change reflects lesion size.     

Electrophysiologic characteristics and radiofrequency catheter ablation in children with Wolff-Parkinson-White syndrome

BACKGROUND: The majority of cardiac arrhythmias in children are supraventricular tachycardia, which is mainly related to an accessory pathway (AP)-mediated reentry mechanism. The investigation for Wolff-Parkinson-White (WPW) syndrome in adults is numerous, but there is only limited information for children. This study was designed to evaluate the specific electrophysiologic characteristics and the outcome of radiofrequency (RF) catheter ablation in children with WPW syndrome. METHODS: From December 1989 to August 2005, a total of 142 children and 1,219 adults with atrioventricular reentrant tachycardia (AVRT) who underwent ablation at our institution were included. We compared the clinical and electrophysiologic characteristics between children and adults with WPW syndrome. RESULTS: The incidence of intermittent WPW syndrome was higher in children (7% vs 3%, P=0.025). There was a higher occurrence of rapid atrial pacing needed to induce tachycardia in children (67% vs 53%, P=0.02). However, atrial fibrillation (AF) occurred more commonly in adult patients (28% vs 16%, P=0.003). The pediatric patients had a higher incidence of multiple pathways (5% vs 1%, P<0.001).Both the onset and duration of symptoms were significantly shorter in the pediatric patients. The antegrade 1:1 AP conduction pacing cycle length (CL) and antegrade AP effective refractory period (ERP) in children were much shorter than those in adults with manifest WPW syndrome. Furthermore, the retrograde 1:1 AP conduction pacing CL and retrograde AP ERP in children were also shorter than those in adults. The antegrade 1:1 atrioventricular (AV) node conduction pacing CL, AV nodal ERP, and the CL of the tachycardia were all shorter in the pediatric patients. CONCLUSION: This study demonstrated the difference in the electrophysiologic characteristics of APs and the AV node between pediatric and adult patients. RF catheter ablation was a safe and effective method to manage children with WPW syndrome.     

低温等离子射频治疗声带癌疗效观察和术后评估

目的通过对低温等离子射频(RFA)治疗声带癌的疗效和术后进行评估,探讨RFA在声带癌中的应用效果。方法我院2008年9月至2010年10月采用RFA治疗声带癌35例,术后随访12个月观察治疗效果。结果患者于术后20 d进行动态喉镜检查,32例患者声带手术创面平整光滑、无组织残留、声音一般在1～3个月恢复正常,吞咽功能在1周后也逐渐恢复,无严重并发症发生;有2例术后伤口感染,经伤口换药1个月内恢复;1例患者术后1年局部复发。结论 RFA具有微创、出血少、安全、并发症少等特点,其用于治疗声带癌效果良好。     

Can Lesion Size During Radiofrequency Ablation Be Predicted By the Temperature Rise to a Low Power Test Pulse in Vitro?

During radiofrequency ablation sufficient power must be delivered to achieve a proper lesion, while tissue temperatures are kept below 100 degrees C. Tissue temperature and hence lesion size are determined by electrode to tissue contact and convective cooling, which vary with any obtained electrode position in the beating heart. A tool for evaluation of the combined effect of these parameters prior to ablation to predict the resulting lesion size for any actually obtained electrode position would be valuable. A low power pulse prior to ablation will cause a small increase in tip temperature, which will reflect tissue contact and convective cooling of the tip for that particular electrode position and may thereby predict lesion dimensions after subsequent ablation at that site. Ablation was performed in vitro on strips of left ventricular porcine myocardium during different levels of convective cooling, variable contact pressure, and two electrode orientations in temperature-controlled and power-controlled modes. A 4-mm tip catheter was used. Prior to ablation a 30-second, 0.6-W test pulse was delivered and the increase in tip temperature (DeltaT) registered. The study found that DeltaT and lesion size were mainly affected by the external cooling of the electrode tip and less by the electrode to tissue contact. Increased cooling caused a lower DeltaT (P < 0.001), and the effect on lesion dimensions depended on the ablation mode. For temperature-controlled ablation a larger lesion due to increased power output was obtained (P < 0.0001) for increased cooling, whereas for power-controlled ablation a smaller lesion was obtained for increased cooling (P < 0.05). DeltaT can predict lesion size, but the interpretation of DeltaT depends on the ablation mode. For temperature-controlled ablation a high DeltaT indicates a small lesion and for power-controlled ablation a high DeltaT indicates a large lesion.     

Bidirectional tachycardia eliminated with radiofrequency ablation

This report describes an unusual case of bidirectional tachycardia eliminated with radiofrequency ablation. The tachycardia had alternating right and left bundle branch block morphology on a beat-to-beat basis and was successfully eliminated by ablating the right and left bundle branch block ventricular ectopic beats present during sinus rhythm.     

Right diaphragm paralysis following cardiac radiofrequency catheter ablation for inappropriate sinus tachycardia

We describe a case of permanent right diaphragm paralysis following a radiofrequency cardiac ablation procedure. The relationship between the procedure and the phrenic nerve lesion is discussed with respect to the possible pathogenetic mechanisms. Radiofrequency current used in cardiac electrophysiology may cause serious thoracic nerve injuries. Means to avoid this complication are pointed out.     

射频消融治疗阵发性室上性心动过速复发原因分析

目的：分析阵发性室上性心动过速患者行射频消融术后复发的原因，探讨降低术后复发的方法。方法：132例阵发性室上性心动过速患者，行射频消融术，术后每3～6个月随访1次，随访4～24个月。结果：132例患者中，复发10例，总复发率7．58％，其中房室结折返性心动过速复发率为6．52％，左侧房室旁路介导心动过速复发率5．89％，右侧旁路介导心动过速复发率14．28％。行射频消融术患者中，前70例复发率11．43％，后62例复发率3．22％。结论：精确的靶点标测、熟练的操作技巧以及消融方式的正确运用是降低射频消融术复发率的关键。     

缓慢心室率心房扑动患者射频消融术后发生房室传导阻滞分析

目的探讨心房扑动射频消融术后出现房室传导阻滞的原因及对策。方法回顾性分析35例心房扑动患者,存在房室传导比率≥5:1,均采用消融下腔静脉至三尖瓣峡部,终点达到双向阻滞。29例于房扑下消融,6例是转窦性心律后消融,分析术后发生房室传导阻滞的原因。结果 9例患者术后发生I°至高度房室传导阻滞,其中4例患者恢复,5例患者未恢复。结论心房扑动行射频消融术有造成房室传导阻滞可能,但发生率低。缓慢心室率的心房扑动术前可能合并房室传导阻滞,转窦性心律后消融对增加手术安全性及是否存在并发症的判定有帮助。