Objective To investigate the effect of Nifekalant on action potential of atrium and pulmonary vein and the possible clinical efficacy of Nifekalant against atrial tachyarrhythmias.Methods left and right atrium and pulmonary vein removed from 15 white rabbits were made into tissue preparations(0.5 cm?1.5 cm).Action potential was induced by electric stimulation with twofold capture threshold and recorded by standard glass microelectrode technique.Effective refractory periods of left and right atrial and pulmonary vein tissues were measured with burst and programmed stimulation.The Action potentials and effective refractory periods of various tissues were compared between before and after irrigation of Tyrodes fluid containing Nifekalant of 2.13 mg/L.Results After irrigation of Tyrodes fluid containing Nifekalant,APD90 was prolonged[(51?16)ms vs(78?33)ms,P

Objective To analyse long-term follow-up outcome of cryoballoon ablation (CBA) for atrial ifbrillation (AF) in a single center and to investigate the clinical relative factors which affecting the effect. Methods The inpatient, operating and outpatient data of patients, who were treated by CBA for AF in our center from January 2009 to April 2013, were retrospectively analyzed. Left atrium diameter (LAD) was measured by transthoracic echocardiography. Failure-treatment of CBA was defined by episode of AF, atrial lfutter, atrial tachycardia lasted for 30 seconds after 3 months. Results A total of 199 patients were enrolled. The rates of phrenic nerve paralysis, pericardial effusion, transient ischemic attack were 1.5%(n=3), 0.5%(n=1), 0.5%(n=1),respectively. All complications were resolved spontaneously.152 patients had completed follow-up data after ifrst-time CBA during a long-term follow-up of mean 23±14 months, 65 patients (42.8%) treated success. 75 patients with failure-treated were (86.2%) experienced the atrial arrhythmia recurrence in ifrst 12 month. The characteristics of failure-treated patients included with older age[(62±7) years vs. (52±10) years, P=0.0379]and larger LAD[(48±6)mm vs. (43±6) mm, P<0.0001]. The Logistic analysis showed that LAD[OR=0.896(0.842,0.953), P=0.005]and age[OR=1.037 (1.000,1.076), P=0.0488]could individually predict the treat-failure after ifrst CBA, and only LAD[OR=0.876 (0.822,0.935), P < 0.0001]could individually predict the total CBA. Conclusions CBA procedure for AF is safe and effective, and the result of long-term follow-up is preferable. Most atrial arrhythmia are recurred during ifrst 12 month after CBA. LAD can individually predict the failure in treatment of CBA.

Objective: To explore the effect of age and gender on head-up tilt test (HUTT) for diagnosing the patients with suspected vasovagal syncope (VVS).
Methods: A total of 1223 patients who received HUTT in our hospital from 2008-08 to 2012-12 were studied. The patients were from 7 to 79 years of age and divided into 4 groups. Group 1, the patients≤20 years of age, n=145, Group 2, the patients at (21-40) years, n=375, Group 3, the patients at (41-60) years, n=584 and Group 4, the patients>60 years, n=119. The HUTT comprised a 30 min basic phase and 20 min sublingual nitroglycerin provocation phase. According to ECG and blood pressure changes, the HUTT positive patients included vasodepressor type, cardio-inhibitory type and mixed type.
Results: The overall positive rate of HUTT was 51%(624/1223) and the female was higher than male, (60.1%vs 39.9%), P=0.001. The positive rates in 4 age groups were at 68.3%, 49.1%, 48.6% and 47.9% respectively. In HUTT positive patients, there were 51.4% (321/624) patients with mixed type of VVS, 28.7% (179/624) with vasodepressor type of VVS and 19.9% (124/624) with cardio-inhibitory type of VVS. The positive HUTT reaction was inlfuenced by the age as in male:x2=15.65, P=0.016 and in female:x2=18.84, P=0.004. For basic phase of HUTT, there were 74.8%of positive reactions started at 22.5 (17.5-27.5) min of the test without age difference, P>0.05;for sublingual nitroglycerin provocation phase of HUTT, there were 81.9%positive reactions started at 7.5 (5-10) min and the female was earlier than male (7.5 vs 10) min, P=0.004.
Conclusion: There were age and gender differences for HUTT diagnosing the patients with VVS for their positive rate, type and starting time.

OBJECTIVETo map and compare the right atrium in patients with AF to those with atrioventricular nodal reentrant tachycardias (AVNRT, as control group) and to investigate the anatomical and electrophysiological abnormality of the right atrium in AF.

METHODSThe anatomy and electrophysiology of right atrium and cavotricuspid isthmus were evaluated in 20 patients with AF (16 M/4 F, mean age 55.9 +/- 10.68 years) and 26 patients with AVNRT (9 M/17 F, mean age 47.50 +/- 19.56 years) during coronary sinus pacing at 600 ms prior to ablation with electro-anatomical mapping system. Right atrial volume (RAV), the length and width of cavotricuspid isthmus (IsL, IsW), unipolar and bipolar voltage in the right atrium (UniV-RA, BiV-RA) were measured and compared between patients with AF and those with AVNRT.

RESULTSRAV, IsL, IsW, UniV-RA, and BiV-RA were 143.22 +/- 40.72 vs 104.35 +/- 21.06 ml, 39.31 +/- 8.10 vs 32.42 +/- 9.77 mm, 30.54 +/- 7.48 vs 23.15 +/- 6.61 mm, 1.96 +/- 1.24 vs 1.53 +/- 0.91 mv and 1.47 +/- 1.47 vs 1.29 +/- 1.12 mv in AF and AVNRT respectively.

CONCLUSIONThe right atrial volume is larger; both the length and width of cavotricuspid isthmus are greater. Unipolar and bipolar voltages in the right atrium are higher in AF than in AVNRT, suggesting that the enlarged right atrium, increased length and width of cavotricuspid isthmus, and concomitant atrial hypertrophy are important substrates for initiation and perpetuation of typical AF.

Adult ; Aged ; Atrial Flutter ; etiology ; pathology ; physiopathology ; Cardiomegaly ; complications ; Female ; Heart Atria ; pathology ; physiopathology ; Humans ; Male ; Middle Aged ; Tachycardia, Atrioventricular Nodal Reentry ; pathology ; physiopathology

PURPOSETo evaluate and compare the effects of heart rate on conduction velocity in the cavotricuspid isthmus (CTI) and septum in patients with and without typical atrial flutter (AF) using electro-anatomic mapping (EAM) of the right atrium (RA).

METHODSTen patients (age 53+/-10 yrs, 7M/3F) with AF and 13 patients (age 51+/-11 yrs, 5M/8F) with atrioventricular nodal reentrant tachycardia (AVNRT) underwent conventional electrophysiological study, electro-anatomic mapping and radiofrequency ablation. Using EAMs obtained during coronary sinus pacing at pacing cycle length (PCL) 600 ms, 400 ms, and 300 ms, we evaluated conduction velocities in the CTI and septum of RA in 10 patients with AF and compared EAMs to 13 patients with AVNRT to determine whether the conduction slowing required to maintain AFL was related to changes in volume alone or altered RA electrophysiology.

RESULTSConduction velocities in CTI and septum were significantly slower at all PCL when AF was compared to AVNRT (*P<0.05). Additionally, in the AF group, septal conduction velocities were slower at PCL 600 ms and 400 ms, but not at 300 ms compared to CTI (*P<0.05). In AF, during PCL 300, conduction in CTI slowed significantly compared to PCL 600 and 400 ms such that there was no difference between CTI and septum at PCL 300.

CONCLUSIONSThere is slower conduction in the septum compared to the CTI in all patients. However, in patients with AF, there is significant slowing of conduction in the CTI and septum as well as decremental rate-dependent slowing of conduction in the CTI. These findings indicate that in addition to RA enlargement, changes in atrial electrophysiology distinguish AF patients from patients with AVNRT.

Adult ; Atrial Flutter ; physiopathology ; Female ; Heart Atria ; physiopathology ; Heart Conduction System ; physiopathology ; Heart Rate ; physiology ; Humans ; Male ; Middle Aged ; Tachycardia, Atrioventricular Nodal Reentry ; physiopathology ; Tricuspid Valve ; physiopathology