A5051699207- Cardiac electrophysiology and arrhythmias
- Ion channel regulation and function
- Nonlinear Dynamics and Pattern Formation
- Neuroscience and Neural Engineering
- ECG Monitoring and Analysis
- stochastic dynamics and bifurcation
- Cardiac Arrhythmias and Treatments
- Receptor Mechanisms and Signaling
- Protein Structure and Dynamics
- Quantum chaos and dynamical systems
- Chaos control and synchronization
- Gene Regulatory Network Analysis
- Cardiomyopathy and Myosin Studies
- Cardiovascular Effects of Exercise
- Neural dynamics and brain function
- Cardiovascular Function and Risk Factors
- Mitochondrial Function and Pathology
- Electrochemical Analysis and Applications
- Atrial Fibrillation Management and Outcomes
- Cardiac pacing and defibrillation studies
- Neuroscience and Neuropharmacology Research
- Bioinformatics and Genomic Networks
- Microtubule and mitosis dynamics
- ATP Synthase and ATPases Research
- Fungal and yeast genetics research
University of California, Los Angeles
2016-2025
Medical College of Wisconsin
2025
UCLA Health
2004-2023
Planetary Science Institute
2020
First Affiliated Hospital of Xi'an Jiaotong University
2012
St. Luke's Episcopal Hospital
2012
Indiana University – Purdue University Indianapolis
2010-2012
Tokyo Medical and Dental University
2012
Mayo Clinic
2012
University of Padua
2012
Ventricular fibrillation is the leading cause of sudden cardiac death. In fibrillation, fragmented electrical waves meander erratically through heart muscle, creating disordered and ineffective contraction. Theoretical computer studies, as well recent experimental evidence, have suggested that created sustained by property restitution action potential duration (that is, its dependence on previous diastolic interval). The hypothesis states steeply sloped curves create unstable wave...
The synchronization of coupled oscillators plays an important role in many biological systems, including the heart. In heart diseases, cardiac myocytes can exhibit abnormal electrical oscillations, such as early afterdepolarizations (EADs), which are associated with lethal arrhythmias. A key unanswered question is how cellular EADs partially synchronize tissue, required for them to propagate. Here, we present evidence, from computational simulations and experiments isolated myocytes, that...
Background —T-wave alternans, which is associated with the genesis of cardiac fibrillation, has recently been related to discordant action potential duration (APD) alternans. However, cellular electrophysiological mechanisms responsible for alternans are poorly understood. Methods and Results —We simulated a 2D sheet tissue using phase 1 Luo-Rudy model. A steep (slope >1) APD restitution curve promoted concordant T-wave without QRS When pacing was from single site, occurred only when rate...
Abstract —Sudden cardiac death resulting from ventricular fibrillation can be separated into 2 components: initiation of tachycardia and degeneration to fibrillation. Clinical drug studies such as CAST SWORD demonstrated that focusing exclusively on the first component is inadequate a therapeutic modality. The hope for developing effective pharmacological therapy rests comprehensive understanding second component, transition We summarize evidence spatiotemporal chaos, with similarities...
A spatiotemporal system is modeled by a coupled map lattice. Feedback pinnings are used to control chaos of the stabilizing certain unstable reference state. As pinning distribution dense enough, state can be stabilized. If density low, may not approached asymptotically. In this case, however, still effectively suppress and produce rich structures. solution locally stable while transient process extremely long chaotic, very low well chaos.
Spiral wave breakup is a proposed mechanism underlying the transition from ventricular tachycardia to fibrillation. We examined importance of restitution action potential duration (APD) and conduction velocity (CV) stability spiral reentry in two-dimensional sheet simulated cardiac tissue. The Luo-Rudy model was modified eliminate its properties, which are caused by deactivation or recovery inactivation K + , Ca 2+ Na currents ( I respectively). In this model, we find that 1) main...
An advanced integration method for solving reaction-diffusion-type equations cardiac conduction is suggested. Operator splitting and adaptive time step methods were used in this method, which can significantly speed up while preserving accuracy.
The mechanism by which rapid pacing induces ventricular fibrillation (VF) is unclear. We performed computerized epicardial mapping studies in 10 dogs, using 19-beat trains. interval (PI) of the first train was 300 ms and then progressively shortened until VF induced. For each PI, we constructed restitution curves for effective refractory period (ERP). When PI long, activation cycle length (CL) constant throughout mapped region. However, as shortened, there an increase spatiotemporal...
Spatially discordant alternans, where the action potential duration (APD) and intracellular calcium transient (Ca i ) alternate with opposite phase in different regions of tissue, is known to promote wave break reentry. However, this phenomenon not completely understood. It that alternans at cellular level can be caused by dynamical instabilities arising from either membrane voltage ( V m attributable steep APD restitution or (Ca) cycling. Here, we used a mathematical model Ca cycling,...
Excitable cells can exhibit complex patterns of oscillations, such as spiking and bursting. In cardiac cells, pathological voltage called early afterdepolarizations (EADs), have been widely observed under disease conditions, yet their dynamical mechanisms remain unknown. Here, we show that EADs are caused by Hopf homoclinic bifurcations. During period pacing, chaos always occurs at the transition from no EAD to stimulation frequency decreases, providing a distinct explanation for irregular...
Oxidative stress with hydrogen peroxide (H(2)O(2)) readily promotes early afterdepolarizations (EADs) and triggered activity (TA) in isolated rat rabbit ventricular myocytes. Here we examined the effects of H(2)O(2) on arrhythmias intact Langendorff hearts using dual-membrane voltage intracellular calcium optical mapping glass microelectrode recordings. Young adult (3-5 mo, N = 25) 6) exhibited no when perfused (0.1-2 mM) for up to 3 h. However, 33 out 35 (94%) aged (24-26 mo) hearts, 0.1 mM...
Early after-depolarization (EAD), or abnormal depolarization during the plateau phase of action potentials, is a hallmark long-QT syndrome (LQTS). More than 13 genes have been identified as responsible for LQTS, and elevated risks EADs may depend on genotypes, such exercise in LQT1 vs. sudden arousal LQT2 patients. We investigated mechanisms underlying different high-risk conditions that trigger using transgenic rabbit models LQT2, which lack I(Ks) I(Kr) (slow fast components delayed...