Objective : Ultrasound is considered as an alternative enedrgy for post myocardial infarction ventricular tachycardia due to its good penetration through tissues- This study was designed to observe the effects of acou...
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Objective : Ultrasound is considered as an alternative enedrgy for post myocardial infarction ventricular tachycardia due to its good penetration through tissues- This study was designed to observe the effects of acoustic power, duration , repetitive ablations , tissue transducer interface temperature and different sites ofthe ultrasound ablation in vitro- The histological and electrical damages of ultrasound ablation and the feasibility of using ultrasound energy for chronic myocardial infarction scar ablation were also evaluated in vivo- Methods : At 1-8 MHz frequency , Ultrasound ablation were conducted with : ①Different acoustic powers (3-0 ~9-67 W/cm 2) , duration (20 ~90 sec) and repetitive times (1 ~4) ; ②Lesion volume and depth were compared between right and left ventricular muscles ; ③Two different types oftransducers with (model A) and without (model B) direct tissue contact were used in vitro and ①Ultrasound ablation was applied on the epicardium to compare the histological and electrophysiological damages in ten canines ; ②After chronic myocardial infarction , ultrasound ablation was applied on the scar regions in 5 canines in vivo- Results : In vivo : ①While the acoustic powerincreased from 3-0 W/cm 2to 9-67 W/cm 2 ,the lesion depth and volume increased from 1-96 ± 0-18 m m and 64 ±11-40 m m 3to 6-31 ±0-58 m m and 538-51 ±82-63 m m 3, respectively , and there were also significant differences between different powere levels ;Similarly , while the ablation time was prolonged from 30 s to 90 s at fixed acoustic powere levels , the lesion depth and volume significantly increased from 1-93 ±0-22 m m and 58-79 ±13-94 m m 3to 5-75 ±0-45 m m and 445-78 ±82-46 m m 3,respectively ; Repetitive ablations resulted in larger lesion size but such increase was not significant after the fourth time ablation ; Tissue transducerinterface temperature did not displayed a close relationship with thelesion size as acoustic power and ablation time did ; ②Both the lesion dept
The Chinese society of cardiac pacing and electrophysiology organized nationalsurvey on cardiac pacinginthe period from January 1 ,1995 to December31 ,1997- There are 182 hospitals alloverthe country participated inth...
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The Chinese society of cardiac pacing and electrophysiology organized nationalsurvey on cardiac pacinginthe period from January 1 ,1995 to December31 ,1997- There are 182 hospitals alloverthe country participated inthe survey- Followingisthe result ofthe survey- There were atotal number of5 000 new implanted pacemakersin Chinain 1997- It wasincreased rapidly ( > 15% ) annually compared with thatin 1994 (3 000)- There were about700 pacemakers replacement- Itis estimated there were about6 000 pacemakersimplanted in 1998- The single chamber ventricular(VVI) pacing accountedfor79-6 % oftotalpacemakerimplantation- However,the percentage of Dual chamberand rate responsive pacingisincreasing in 1997 (20-4 % ) ,compared with thatin 1996 (16-1% ) and in 1995 (14-5 % )- The indication for pacemaker implantation wassicksinussyndromein 50% ~53 % patientsand atrialventricular blockin41% ~44 % patients,othersin5 % ~7 % patientsfrom 1995 to 1997- coronary heart disease wasfoundin 50 % ~57 % patients- 66-8 % patients were over60 years old and male was 71-4 % in patientsreceived pacingtherapy- The new pacing technique,including automatic mode switch ,auto capture, mutisite pacing to treat atrialfibrillation and congestive heartfailure ,have been usedin China- SincetransvenousImplantable Cardioverter Defibrillators (ICD) were applied in China in 1996 ,there are a total of 71 ICDimplanted before 1998- Allthe devices werethethird generationICDincluded MedtronicJewel,CPIVantak seriesand Pacesetter Angstrom- The mean age ofpatients was48-7 years,61 males and 10 females- Most ofthem suffered from coronary heart disease and dilated cardiomyopathy- Allthe patients had syncope outof hospital and ventricular fibrillation was found in 27 patients and ventricular tachycardia was found in other 44 patients- Allthe implantation were performed inthe catheterlaboratory without complication- There are total about 20 000 cases were undertaken catheter ablation in China- The arrhythmias for ablation i
Objective : To compare posterior isthmus (inferior vena cava tricuspid annulus isthmus) ablation technique and septal isthmus (tricuspid annulus Eustachian ridge isthmus) ablation technique for typical atrialflutter- ...
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Objective : To compare posterior isthmus (inferior vena cava tricuspid annulus isthmus) ablation technique and septal isthmus (tricuspid annulus Eustachian ridge isthmus) ablation technique for typical atrialflutter- Methods :Thirty five patients ( mean age 53 ±15 years) with typical atrial flutter were randomly assigned to undergo radiofrequency catheter ablation performed with posterior isthmus ablation technique (PIgroup ,15 patients) or septal isthmus ablation technique (SIgroup ,20 patients)- Radiofrequency energy was used to create linear lesion from tricuspid ring to inferior vena cava in the PIgroup and from tricuspid ring to Eustachian ridge in the SIgroup- The ablation technique was changed to the other,if one of the ablation techniques failed to block the isthmus after eight applications of radiofrequency energy- The endpoint of successful ablation included a complete bidirectional conduction block atisthmus and inability to induce atrial flutter- Results : Atrialflutter was present atthe onset of ablation in 10 patients of the PIgroup and in 15 patients of the SIgroup , however the cycle lengths of atrialflutter between the two groups were 240 ±30 ms and 220 ±23 ms ( p < 0-05) ,respectively- The endpoint of successful ablation was achieved in all of the patients without any complication- The ablation technique was changed for two patientsin both groups afterthe primary ablation technique was unsuccessful- The times ofradiofrequency application and proceduretime were notsignificantly differentin both groups- During a mean follow up of 15-4 ±3-8 months ,one patient (PIgroup) experienced atrialflutter recurrence- Conclusion : Radiofrequency ablation oftypical atrialflutteris safe and effective with eitherthe posterioristhmus ablation technique orthe septal isthmus ablation technique- The ablation success rate can be increased when these two techniques are used alternatively-
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