高频通气膈肌起搏对COPD病人血气,呼吸肌功能,膈肌活动度和潮气量的影响

目的观察高频通气膈肌起搏（ＨＤＰ）对慢性阻塞性肺病（ＣＯＰＤ）治疗作用。方法１９例ＣＯＰＤ病人给予ＨＤＰ治疗。结果ＨＤＰ可增加伴有或不伴有呼吸衰竭的ＣＯＰＤ患者ＰａＣＯ２、ＳａｔＯ２膈肌活动度和潮气量,而对ＰａＣＯ２、口腔最大吸气压、口腔最大呼气压无明显的影响。结论ＨＤＰ对ＣＯＰＤ有较好的治疗作用,短时治疗对呼吸肌功能无明显的影响。     

HL-1细胞培养及房颤细胞模型的建立

目的:利用HL-1细胞建立快速起搏模型,对心房颤动(atrial fibrillation,AF)早期的重构现象进行初步研究。方法:培养HL-1细胞,建立快速电场刺激起搏细胞模型,利用全细胞膜片钳技术记录刺激前后HL-1细胞的动作电位周期,透射电镜观察细胞超微结构的变化。结果:将细胞接种于培养皿中,72 h后细胞呈融合状态,全细胞膜片钳记录培养HL-1细胞及经电场刺激(600次/min,1 V/cm)24 h后的心房肌细胞的动作电位周期,动作电位周期分别为106 ms,45 ms,刺激前后差异有统计学意义(P0.05)。透射电镜观察到刺激后HL-1细胞超微结构发生去分化改变。结论:经快速起搏24 h后,HL-1细胞发生了电及结构重构;利用HL-1细胞建立快速起搏的房颤模型,可以对房颤早期的重构机制进行研究。     

Continuation and bifurcation analysis of a periodically forced excitable system

The response of an excitable cell to periodic electrical stimulation is modeled using the FitzHugh-Nagumo (FHN) system submitted to a gaussian-shaped pacing, the width of which is small compared with the action potential duration. The influence of the amplitude and the period of the stimulation is studied using numerical continuation and bifurcation techniques (AUTO97 software). Results are discussed in the light of prior experimental and theoretical findings. In particular, agreement with the documented behavior of periodically stimulated cardiac cells and squid axons is discussed. As previously reported, we find many different "M:N" periodic solutions, period-doubling sequences leading to seemingly chaotic regimes, and bistability phenomena. In addition, the use of continuation techniques has allowed us to track unstable solutions of the system and thus to determine how the different stable rhythms are connected with each other in a bifurcation diagram. Depending on the stimulus amplitude, the aspect of the bifurcation diagram with the stimulus period as main varying parameter can vary from very simple to very complex. In its most developed structure, this bifurcation diagram consists of a main "tree" of period-2(P) branches, where the 1:1, 1:0, 2:2, 2:1,... rhythms are located, and of several closed loops made up of period-{N x 2(P)} branches (N>2), isolated from each other and from the main tree. It is mainly on such loops that N:1 rhythms (N>2) on one hand, and N:N-1 or Wenckebach rhythms (N>2) on the other hand, are located. Stable M:N and M:N-1 rhythms (M>or=N) can be found on the same branch of solutions. They are separated by a region of unstable solutions at small stimulus amplitudes, but this region shrinks gradually as the stimulus amplitude is raised, until it finally disappears. We believe that this property is related to the excitability characteristics of the FHN system. It would be interesting to know if it has any correspondence in the behavior of real excitable cells.     

Gastric Pacing for Morbid Obesity: Plasma Levels of Gastrointestinal Peptides and Leptin

Objective: A gastric pacemaker has been developed to treat morbid obesity. Patients experience increased satiety, the ability to reduce food intake, and a resultant weight loss. However, the mechanism behind the changed eating behavior in paced patients is still under investigation. Research Methods and Procedures: This study was performed on 11 morbidly obese patients (mean BMI, 46.0 kg/m²) treated with gastric pacing. The peripheral blood levels of satiety signals of cholecystokinin (CCK), somatostatin, glucagon‐like peptide‐1 (GLP‐1), and leptin were studied 1 month before gastric pacer implantation, 1 month after implantation, and 6 months after activation of electrical stimulation. Blood samples were drawn 12 hours after fasting and in response to a hypocaloric meal (270 kcal). Patients were followed monthly for vital signs and weight level. Results: Gastric pacing resulted in a significant weight loss of a mean of 10.4 kg (4.4 BMI units). No negative side effects or complications were observed during the treatment. After activation of the pacemaker, meal‐related response of CCK and somatostatin and basal levels of GLP‐1 and leptin were significantly reduced (p < 0.05) compared with the tests before gastric pacing. The weight loss correlated significantly with a decrease of leptin levels (R = 0.79, p < 0.01). Discussion: Gastric pacing is a novel and promising therapy for morbid obesity. Activation of the gastric pacer was associated with a decrease in plasma levels of CCK, somatostatin, GLP‐1, and leptin. More studies are necessary to elucidate the correlations between satiety, weight loss, and digestive neuro‐hormone changes.     

经食道心房调搏术及食道心电图在心律失常中的应用

目的:分析经食道心房调搏术(TEAP)及食道内心电图(EECG)在心律失常中的应用价值。方法:选取2018年6月至2019年12月于我院行食道心电图及经食道调搏的患者189例,其中男80例,女109例,年龄11~83岁。结果:54例为房室结折返性心动过速(AVNRT),34例为房室折返性心动过速(AVRT),8例为房性心动过速(AT),4例为心房扑动(AF),6例为心房颤动(Af),5例为室性心过速,78例为室早或其他。共105例心律失常患者拟行食道心房调搏终止心动过速,所有AVNRT和AVRT患者及17例AT患者经食道心房调搏S1S1成功转为窦律,50例AVNRT、32例AVRT、6例AT、3例AF及2例VT患者通过射频消融术成功根治。其中1例11岁AT患者因无法耐受食道调搏,未能转为窦律,患者经静推普罗帕酮后次日转为窦律。共97例患者拟行食道心房调搏诱发,共49例诱发出心动过速,1例左后分支型室速经静滴异丙肾上腺素后诱发心动过速,且仍需静滴异丙肾上腺素后经心房食道调博终止心动过速,后经射频消融术成功根治。结论:TEAP及EECG可用于复杂心律失常的诊断及治疗,是一种相对安全、临床容易掌握的技术,值得推广。     

Dual chamber pacing mode in an atrial antitachycardia pacing device without a ventricular lead – A necessary evil

We present a case of a single chamber atrial pacemaker implanted for sinus node dysfunction and treatment of macroreentrant atrial tachycardias with atrial antitachycardia pacing. The patient presented with sustained atrial tachycardia above the detection rate, however, the device was unable to detect the tachycardia and did not deliver the programmed therapy. We discuss the nuances of the atrial tachyarrhythmia detection algorithms, and the programming strategies to maximize detection of atrial arrhythmias in a single chamber atrial pacemaker.     

The femoral route revisited: an alternative for pectoral pacing lead implantation

We describe the implantation via the femoral vein of a dual-chamber pacing system with lumenless, catheter-delivered pacing leads in a patient in whom subclavian access on both sides was obstructed. (Neth Heart J 2010;18:42-4.)     

Evaluation of Bachmann Bundle Pacing Versus Right Atrial Pacing in Prevention of Atrial Fibrillation After Coronary Artery Bypass Surgery

Background

In patients undergoing coronary artery bypass surgery (CABGS), occurrence of atrial fibrillation (AF) is common in the postoperative period and is associated with increased morbidity with longer intensive unit care (ICU) and hospital stay. Prevention with antiarrhythmic drugs is of limited success and associated with significant side effects. Therefore alternative approaches, such as Bachmann Bundle pacing, are required.

Methods and Results

154 consecutive patients, mean age 58±8.8 years, including 134 males and 20 females, were randomized to three groups; Group I : No pacing n= 54, Group II : RA pacing n= 52, Group III : Bachmann Bundle pacing n= 48. All the groups were well matched with regard to age, left atrial size, ejection fraction and use of beta blockers. Patients in Groups II and III were continually paced at a rate of 100 beats per minute (bpm) or at 10 bpm more than patients'' intrinsic heart rate. All the patients were monitored for 72 hours by telemetry and occurrence of AF was noted. Incidence of AF was 0% (none of 48 patients) in Group III as compared to 16.6% in Group I (9 of 54 patients) (p 0.003) and 12.5% in Group II (5 of 52 patients) (p 0.03). There was a trend towards shorter ICU stay in Group III (3.9 days) as compared to Group II (4.5 days) and Group I (4.1 days). Among the three groups, the reduction in mean P wave duration also was greater in Bachmann bundle paced group.

Conclusion

In patients undergoing CABGS, Bachmann bundle pacing is superior to right atrial / no pacing in the post operative period for preventing occurrence of AF and reducing ICU stay, commensurate with a reduction in mean P wave duration on surface ECG.     

Non-invasive Determination of the Optimized Atrioventricular Delay in Patients with Implanted Biventricular Pacing Devices

Background

Biventricular (BiV) is extensively used in the treatment of congestive heart failure but so far no recommendations for optimized programming of atrioventricular-delay (AVD) settings have been proposed. Can AVD optimization be performed using a simple formula based on non-invasive doppler-echocardiography?

Methods

25 patients (ejection fraction 30±8%) received BiV ICDs. Doppler-echocardiographic evaluation of diastolic and systolic flow was performed for different AVDs (30ms to 150ms) and different stimulation sites (left ventricular (LV), right ventricular and BiV). The optimal atrioventricular delay was calculated applying a simple formula based on systolic and diastolic mechanical delays determined during doppler-echocardiography.

Results

The mean optimal AVD was calculated to be 112±29ms (50 to 180ms) for BiV, 95±30ms (65 to 150ms) for LV and 75±28ms (40 to 125ms) for right ventricular pacing with wide interindividual variations. Compared to suboptimal AVDs diastolic optimization improved preejection and ejection intervals independent to pacing site. Optimization of the AVD significantly increased ejection time during BiV pacing (279ms versus 266ms; p<0.05). Compared to LV or right ventricular pacing BiV pacing produced the shortest mean pre-ejection and longest ejection intervals as parameters of improved systolic ventricular contractile synchrony. Diastolic filling times were longest during BiV pacing compared to LV or RV pacing.

Conclusions

Individual programming of BiV pacing devices increases hemodynamic benefit when implementing the inter-individually widely varying electromechanical delays. Optimization applying a simple formula not only improves diastolic ventricular filling but also increases systolic functional parameters.     

Outcomes using a single tapered dilator for Micra leadless pacemaker implant

ObjectivesComparison of outcomes, device deployment time (DT), and total time (TT) using a single tapered Coons dilator versus sequential serial dilation for implantation of the Micra leadless pacemaker.BackgroundMicra leadless pacemaker placement requires a 23 French Micra introducer sheath (MIS) for percutaneous delivery. We sought to evaluate outcomes with use of a single tapered Coons dilator (CD) versus sequential serial dilatation (SD) method to facilitate insertion of the Micra introducer sheath.Methods35 patients were included in the SD arm and 49 in the CD arm. DT and TT were recorded in minutes and cost in dollars. Analysis was performed using independent t-test between two groups and one-way ANOVA to evaluate inter-operator variability in the CD arm.ResultsBoth DT and TT were significantly lower for the CD arm (15.1 ± 5.1 vs 23.5 ± 9.3, p < 0.0005 and 29.9 ± 14 vs 39.3 ± 13.5 min, p = 0.000374; respectively). The cost was also significantly lower using a CD versus SD. There was no inter-operator variability in the CD arm between 6 operators (p = 0.177 for DT and p = 0.304 for TT). No complications occurred in the SD arm. There were 3 vascular access site complications in the CD arm, all of which occurred early in the operator’s experience.ConclusionCoons dilator is an efficient and cost-effective method for vascular dilatation to facilitate Micra leadless pacemaker insertion. Rate of complications is low and expected to improve with greater experience.