Publications by authors named "Alejandra Miyazawa"
Background: Ventricular tachycardia (VT) reduces cardiac output through high heart rates, loss of atrioventricular synchrony, and loss of ventricular synchrony. We studied the contribution of each mechanism and explored the potential therapeutic utility of His bundle pacing to improve cardiac output during VT.
Methods: Study 1 aimed to improve the understanding of mechanisms of harm during VT (using pacing simulated VT).
Background: The prognostic impact of ventricular tachycardia (VT) catheter ablation is an important outstanding research question. We undertook a reconstructed individual patient data meta-analysis of randomised controlled trials comparing ablation to medical therapy in patients developing VT after MI.
Methods: We systematically identified all trials comparing catheter ablation to medical therapy in patients with VT and prior MI.
Aims: Left bundle branch pacing (LBBP) can deliver physiological left ventricular activation, but typically at the cost of delayed right ventricular (RV) activation. Right ventricular activation can be advanced through anodal capture, but there is uncertainty regarding the mechanism by which this is achieved, and it is not known whether this produces haemodynamic benefit.
Methods And Results: We recruited patients with LBBP leads in whom anodal capture eliminated the terminal R-wave in lead V1.
Septal scar as a barrier to left bundle branch area pacing.
Pacing Clin Electrophysiol
September 2023
Article Synopsis
- Researchers explored how septal scar tissue affects the success of left bundle branch area pacing (LBBAP) in patients needing bradycardia pacing or cardiac resynchronization therapy.
- They conducted a study with 35 patients who had preprocedural assessments using cardiac MRI to evaluate scar extent before attempting lead implantation.
- Results showed that successful lead deployment was more likely in patients with less septal scar, indicating that extensive scar tissue may hinder the implantation process and suggesting possible alternative strategies for those patients.
Article Synopsis
- The study compares the effectiveness of left bundle branch area pacing (LBBAP) and His bundle pacing (HBP) against biventricular pacing (BVP) in improving cardiac resynchronization therapy (CRT).
- Nineteen patients participated, showing that HBP was more effective in reducing total ventricular activation time (TVAT) than LBBAP, while both were better than BVP.
- Despite HBP performing better overall, LBBAP showed similar benefits in left ventricular electrical resynchronization and had a comparable acute haemodynamic response.
Laser Doppler flow for the hemodynamic differentiation of tachycardia.
Pacing Clin Electrophysiol
February 2023
Article Synopsis
- Implantable cardioverter defibrillators (ICDs) help prevent sudden heart problems, but sometimes they can give shocks at the wrong times, which is not good for people.
- This study looked at using a special device called laser Doppler flowmetry to check how the heart is doing during fast heart rates caused by atrial and ventricular issues.
- The results showed that laser Doppler flowmetry worked well to measure blood flow and was better at spotting heart problems than just looking at the heart rate alone.
Guidelines recommend patients undergoing a first pacemaker implant who have even mild left ventricular (LV) impairment should receive biventricular or conduction system pacing (CSP). There is no corresponding recommendation for patients who already have a pacemaker. We conducted a meta-analysis of randomized controlled trials (RCTs) and observational studies assessing device upgrades.
View Article and Find Full Text PDFPacing therapy aims to improve overall cardiac function by normalizing cardiac electrical activation. Although hemodynamic measurements allow the impact of cardiac pacing on cardiac function to be quantified, the protocol is crucial to minimize the effect of noise and achieve greater precision. Multiple steps can be undertaken to optimize accuracy of hemodynamic measurements.
View Article and Find Full Text PDFBackground: Hemodynamically optimal atrioventricular (AV) delay can be derived by echocardiography or beat-by-beat blood pressure (BP) measurements, but analysis is labor intensive. Laser Doppler perfusion monitoring measures blood flow and can be incorporated into future implantable cardiac devices. We assess whether laser Doppler can be used instead of BP to optimize AV delay.
View Article and Find Full Text PDFBackground: His bundle pacing (HBP) is an alternative to biventricular pacing (BVP) for delivering cardiac resynchronization therapy (CRT) in patients with heart failure and left bundle branch block (LBBB). It is not known whether ventricular activation times and patterns achieved by HBP are equivalent to intact conduction systems and not all patients with LBBB are resynchronized by HBP.
Objective: To compare activation times and patterns of His-CRT with BVP-CRT, LBBB and intact conduction systems.
Background: ST2 is a circulating biomarker that is well established for predicting outcome in heart failure (HF). This is the first study to look at ST2 concentrations in optimally treated patients with stable but significant left ventricular systolic dysfunction (LVSD) compared to patients with severe aortic stenosis (AS).
Methods: Two cohorts were retrospectively studied: 94 patients undergoing transcatheter aortic valve implantation for severe AS (63 with normal ejection fraction [EF] and 31 with reduced EF), and 50 patients with severe LVSD from non-valvular causes.
Article Synopsis
- New pacing technologies in heart therapy allow doctors to customize treatment better by trying different pacing spots in the heart.
- The iSpot trial tested seven different ways to pace the heart, measuring blood pressure and heart performance before and after switching methods.
- Results showed that only a few patients really benefited from the new methods, and the common way of averaging measurements could make it seem like more patients improved than really did.