UNLABELLEDObjective To compare the impact of right ventricular apical (RVA) versus right ventricular outflow tract (RVOT) pacing on left ventricular systolic synchronization.

METHODSSixty patients were prospectively recruited and randomized into RVA group (n=30) with the right ventricle leads placed in the RVA and RVOT group (n=30) with right ventricle leads placed in the septum of the RVOT. Speckle tracking imaging was performed with 100% ventricle pacing to measure the differences in the time to maximum left ventricle (LV) radial strain.

RESULTSIn RVA group, the difference in the time to 6-segment maximum LV radial strain after pacing was 105.27 ± 19.74 ms, significantly greater than that in RVOT group (41.65 ± 12.17 ms, P<0.001). The standard difference of time to 6-segment maximum LV radial strain was also significantly greater in RVA group than in RVOT group (42.71 ± 17.63 vs 17.63 ± 5.62 ms, P<0.001).

CONCLUSIONLeft ventricle systolic synchronizaition after RVOT pacing is superior to RVA pacing.

Cardiac Pacing, Artificial ; methods ; Heart ; Heart Ventricles ; Humans ; Systole

Temporary cardiac pacing is an essential technique in the diagnosis and treatment of arrhythmias. Due to its urgency, complexity, and uncertainty, it is necessary to develop an evidence-based emergency operation norms. Currently, there is no specific consensus guidelines at home or abroad. The Emergency Branch of Chinese Medical Association organized relevant experts to draft the Chinese emergency expert consensus on bedside temporary cardiac pacing (2023) to guide the operation and application of bedside cardiac pacing. The formulation of the consensus adopts the consensus meeting method and the evidentiary basis and recommendation grading of the Oxford Center for Evidence-based Medicine in the United States. A total of 13 recommendations were extracted from the discussion on the methods of bedside temporary cardiac pacing, the puncture site of transvenous temporary cardiac pacing, the selection of leads, the placement and placement of leads, pacemaker parameter settings, indications, complications and postoperative management. The recommended consensus includes the choice between transcutaneous and transvenous pacing, preferred venous access for temporary transvenous pacing, the target and best guidance method for implantation of bedside pacing electrodes, recommended default pacemaker settings, recommended indications for sinoatrial node dysfunction, atrioventricular block, acute myocardial infarction, cardiac arrest, ventricular and supraventricular arrhythmias. They also recommended ultrasound guidance and a shortened temporary pacing support time to reduce complications of temporary transvenous cardiac pacing, recommended bedrest, and anticoagulation after temporary transvenous pacing. Bedside temporary cardiac pacing is generally safe and effective. Accurate assessment, correct selection of the pacing mode, and timely performance of bedside temporary cardiac pacing can further improve the survival rate and prognosis of related emergency patients.
Humans ; Cardiac Pacing, Artificial/methods* ; Pacemaker, Artificial ; Arrhythmias, Cardiac/therapy* ; Myocardial Infarction/therapy* ; Electrodes

The unipolar/bipolar pacing mode of pacemaker is related to its circuit impedance, which affects the battery life. In this study, the in vitro experiment scheme of pacemaker circuit impedance test was constructed. The human blood environment was simulated by NaCl solution, and the experimental environment temperature was controlled by water bath. The results of in vitro experiments showed that under the experimental conditions similar to clinical human parameters, the difference between the circuit impedance of bipolar mode and unipolar mode is 120~200 Ω. The results of the in vitro experiment confirmed that the circuit impedance of bipolar circuit was larger than that of unipolar mode, which was found in clinical practice. The results of this study have reference value to the optimization of pacing mode and the reduction of pacemaker power consumption.
Cardiac Pacing, Artificial/methods* ; Electric Impedance ; Humans ; Pacemaker, Artificial ; Prostheses and Implants

Arrhythmias, Cardiac ; etiology ; prevention & control ; Cardiac Pacing, Artificial ; adverse effects ; methods ; Humans

AIMTo evaluate the effects of atria-His bundle sequential pacing on cardiac electrophysiology and heamodynamics in dogs.

METHODSIn 20 opening chest anesthetized dogs, platinum electrodes were fixed at the epicardium of right atria (RA) and the right ventricular apex (RVA) respectively, pacing right atria and the right ventricle. A special lead was located at His bundle (based on a optical "H" wave and narrow duration of the QRS complexes recorded in ECG), pacing His bundle. Cardiac electrophysiology and hemodynamics parameters were compared in the different pacing models RA(AAI, RVA-(VVI), HisB-(VVI) single chamber pacing and RA-RVA(DDI), RA-HisB(DDI) dual chamber pacing.

RESULTSThe threshold of His B pacing is similar to that of RVA pacing. Cardiac output (CO) is increased in pacing of RA(AAI), His B-(VVI) and RA-His B(DDI). It is increased by 29.64% in pacing of RA-His B(DDI) (P < 0.01) and by 0.25% (P > 0.05) in pacing of RA-RVA(DD1) While CO is decreased by 5.41% in RVA-VVI) pacing (P > 0.05). SV, LVSW and RVSW of RA-HisB(DDI) pacing are superior to those in RVA-VVI) and RA-RVA(DDI) pacing.

CONCLUSIONRight atria-His bundle sequence pacing significantly improves cardiac function compared with the other model pacing because it maintains normal physiological electronic activity sequence and systolic synchrony. It will be adapted to clinical application.

Animals ; Bundle of His ; physiology ; Cardiac Electrophysiology ; Cardiac Pacing, Artificial ; methods ; Dogs ; Female ; Heart Atria ; Hemodynamics ; Male

AIMTo approach the effects of multi-site synchronous ventricular pacing on myocardial mechanics and cardiac work.

METHODSFive modes of multi-site synchronous ventricular pacing were randomly performed in 12 dogs with anesthetized, opened chest and artificial-ventilation. Some parameters were measured simultaneously including: the peak of left ventricular pressure rise and fall (+/- dp/ dt(max)), the time constant of left ventricular relaxation(tau), the muscle tensile force in left/right ventricular wall (V-tensile force, V-TF), SV, LVSW and RVSW.

RESULTSThe myocardial systolic mechanical parameters: +dp/dt(max) and LV-TF of cHisB-LVPL and RVA-LVPL pacing by biventricular pacing modes were increased than that of cHisB-RVA pacing in right ventricular bifocal pacing mode. +dp/dt(max) in above two groups of biventricular pacing was increased than that in cHisB-RVA pacing. Tau value of cHisB-LVPL and RVA-LVPL pacing modes were shorted than that of cHisB-RVA pacing. The above parameters of cHisB-RVA-LVPL and cHisB-RVA-LVA biventricular trifocal pacing were superior to that of cHisB-LVPL and RVA-LVPL biventricular pacing. The +dp/dt(max), LV-TF and RV-TF of cHisB-RVA-LVPL pacing were increased as compared with that of cHisB-RVA-LVA pacing (P > 0.05). The -dp/dt(max) in cHisB-RVA-LVPL pacing were increased by 6.0% and tau value was shorted by 3.7% compared with those in cHisB-RVA-LVA pacing (P > 0.05). SV, LVSW and RVSW of cHisB-LVPL and RVA-LVPL biventricular pacing were increased than those of cHisB-RVA bifocal pacing. The above parameters of cHisB-RVA-LVPL pacing were increased than that of cHisB-RVA-LVA and cHisB-LVPL pacing.

CONCLUSIONIt was explained that the cHisB-RVA-LVPL biventricular trifocal sites synchronous pacing mode would increase the velocity of ejection and filling during myocardial contraction and relaxation and enhance cardiac work by maintaining normal VSS.

Animals ; Cardiac Pacing, Artificial ; methods ; Dogs ; Female ; Heart ; physiology ; Heart Ventricles ; Male ; Myocardium

Cardiac Pacing, Artificial ; methods ; Female ; Heart Failure ; physiopathology ; therapy ; Humans ; Male ; Middle Aged ; Ventricular Function, Left

This study was conducted to assess the ability of two-dimensional tissue tracking (2DTT) to evaluate changes in left ventricular (LV) myocardial function associated with sustained high electrical pacing. Pacemakers were implanted at the right ventricular (RV) apex of five female Beagles, and sustained high electrical pacing of 250 beats per minute (bpm) was performed for three consecutive weeks. Conventional echocardiography and 2DTT were performed at baseline, and at every week for three weeks with pacing. The baseline parameters were then compared to those of weeks 1, 2, and 3. Three weeks of pacing resulted in significant reduction of radial and circumferential global strains (p < 0.001). Regional analysis revealed reduction of segmental strains in both radial and circumferential directions, as well as increased dyssynchrony after three weeks of pacing in the radial direction (p = 0.0007). The results of this study revealed the ability of 2DTT to measure radial and circumferential strains in dogs with sustained high-electrical pacing, and allowed assessment of global and regional myocardial function and the degree of dyssynchrony.
Animals ; Cardiac Pacing, Artificial ; Dogs ; Echocardiography/*methods ; Female ; Heart Rate ; Heart Ventricles/*ultrasonography ; *Ventricular Function, Left

Aged ; Cardiac Pacing, Artificial ; adverse effects ; Echocardiography ; methods ; Heart Failure ; diagnostic imaging ; etiology ; Humans ; Male

A cardiac stimulator for rapid atrial pacing animal model was designed in this paper. According to the needs of clinical research, output pulse parameters of the cardiac stimulator can be designed. The cardiac stimulator will be controlled through magnet. Efficiency of the cardiac stimulator was validated by animal experiments.
Animals ; Cardiac Pacing, Artificial ; Electric Stimulation ; instrumentation ; methods ; Equipment Design ; Heart Atria ; Models, Animal