Pulmonary Artery Pressure and Right Heart Evaluation for Patients Requiring Physiological Pacing Treatment

With the aging of society, the use of cardiac pacing in patients with irreversible bradycardia is increasingly widespread. As early as the 1950s, right ventricular pacing (RVP) began to be used in patients with atrioventricular block or sick sinus syndrome, but in fact such pacing could cause ventricular asynchrony, which could lead to long-term myocardial perfusion injury, valvular regurgitation, heart failure, and increased risk of ventricular tachycardia and ventricular fibrillation. The latest guideline recommended reducing the proportion of right ventricular pacing. Additionally, in patients with heart failure with reduced ejection fraction (EF ≤ 35%) and complete left bundle branch block, cardiac resynchronization therapy (CRT) with biventricular pacing (BVP) has been recommended to improve cardiac function, but only about 30% of patients benefit from it, which may be related to poor left ventricular pacing site and myocardial scarring. In theory, His bundle pacing (HBP) compared with RVP can reduce the risk of functional tricuspid regurgitation when the lead position lies on the atrial side of the tricuspid valve, which may improve the right heart function and pulmonary artery pressure. In 2021, Domenico Grieco et al. explored the effect of HBP on right heart function. After 6 months of follow-up, it was found that HBP improved right heart function and pulmonary artery pressure compared with RVP.

At present, there are few discussions on the effect of physiological pacing on right ventricular hemodynamics, and the sample size is small. Internationally, the discussion of the assessment of hemodynamics is limited to non-invasive evaluation (such as echocardiography, ECG, SPECT) The gold standard for right heart hemodynamics evaluation is the measurement of invasive right heart catheterization, and there has been no relevant research so far, so the investigators further designed a study of the effect of physiological pacing on hemodynamics.

This study was designed to investigate the acute and chronic effect of different pacing methods on the function of pulmonary artery and right heart.

Studied population: The investigated population are patients eligible for pacemaker implantation and cardiac resynchronization therapy and specified as followed:

1. age over 18; 2. persistent atrial fibrillation patients with uncontrolled heart rate requiring atrioventricular node ablation; 3. heart failure patients with EF≤35% and complete left bundle branch block; 4. patients with sick sinus syndrome or atrioventricular block eligible for pacemaker implantation.

Investigated procedure: Physiological pacing as the principal studied procedure is defined as pacing with ventricular lead implanted at proximal/distal His bundle or left bundle branch. While right ventricular pacing was defined as conventional pacing with ventricular lead implanted at right ventricular apex.

Importantly, Swan-Ganz catheter was performed before and after physiological pacing. By the internal jugular vein before the pacemaker implantation procedure. After the measurement, the catheter was indwelled and measurement was taken. Thereafter, pacemaker implantation procedure was followed. After completing electrode fixation and continuous ventricular pacing for at least 5 minutes, ensuring ventricular pacing ratio \> 80%, the SW catheter measurement was performed again to acquire indices under physiological pacing.

Follow up: The study is designed to have scheduled follow-up at 1 month, 3-month, 6-month and 12 months after procedure. Primary endpoint is a composite endpoint of all-cause mortality and HF rehospitalization. And other imageological measurement (echocardiography) biochemical test (blood BNP) and functional evaluation (6MWT) were performed to appraise the impact of physiological pacing on the condition of the participants.

Eligibility Criteria:
Inclusion Criteria:

* age over 18
* persistent atrial fibrillation patients with uncontrolled heart rate requiring atrioventricular node ablation
* patients with sick sinus syndrome or atrioventricular block eligible for pacemaker implantation
* patients who can understand and sign informed consent

Exclusion Criteria:

* age below 18 or over 99
* concomitant diseases that may affect right heart function, including COPD, pulmonary infection, history of pulmonary embolism or right myocardial infarction, myocarditis, systemic disease
* patients with temporary pacemaker implanted
* right heart catheterization contraindications, including acute infection and embolic events