睏睴睴睴瞤睴 人用人人 Cardiac Arrhythmia C: AFib 量目 D: VT E: VT-TdP
Cardiac Arrhythmia
A normal rhythm ORS premature ventricular beat 人人人入人 C paroxysmal supraventricular tachycardia arrhythmias (PSVT) D atrial fibrillation Abnormal pacemaker, -y rhythm and Ay E atral flutter with variable AV conduction coordination ofheart beats. +++++++++++4+++++ all arrhythmias result from F atrial flutter with 1: 1 AV conduction (1)disturbances in impulse ormation G monomorphic ventricular tachycardia (2)disturbances in impulse conduction H Torsades de Pointes (3)both. ventricular fibrillation
arrhythmias Abnormal pacemaker, rhythm and AV coordination of heart beats. all arrhythmias result from (1) disturbances in impulse formation, (2) disturbances in impulse conduction, (3) both
A. Electrophysiological basis of arrhythmias o 1. Normal cardiac electrophysiology u Excita bility: ability to produce action potentials maximal diastolic potentialS(MDP) threshold levels u Automaticity: pacemaker phase 4 slope u Conductivity: ability to conduct impulse conduction pathways, phase 0 amplitude
A. Electrophysiological basis of arrhythmias 1. Normal cardiac electrophysiology Excitability: ability to produce action potentials maximal diastolic potentials (MDP) threshold levels Automaticity: pacemaker phase 4 slope Conductivity: ability to conduct impulse conduction pathways, phase 0 amplitude
0 mV Fast response cell 100ms Ca Ca Outside Membrane ATP Diastolic channel Channel currents Pump Exchanger currents Action potential and ion transport
Action potential and ion transport Fast response cell
inward outward 13 Phase 4 Gene/protein Na’ current SCN5A/Nav 1.5 Ca L-typ CACNA∥Cav1.2 Action current L T-type CACNA1G.∥cav3.1.32 potential transient KCND3/Ky 4.3 and ion outward current KCNA4/Kv 1.4 transport KCNA1/KVLQT 1 delayed rectifiers KCNH2/hERG (k) KCNA5/Kv 1.5 CFTR/CFTR Fast response cell inward rectifier, IK1 三 KCNJ1/Kir 2.1 pacemaker current↓ J HCN2,4/HCN2,4 Na*-Ca2* exchange SLC8A1/NCX 1 Na*, K+-ATPase NKAIN1-4/Na, K-pump
Action potential and ion transport Fast response cell
40 APD nactivated stimulus -40 open 80 ERP rest APD +20 2 0 20 RRP I 0 SNP ERP 60 100 50100150200250300350 Action potential Duration (APD) and effective refractory period (ERP)
Action potential Duration (APD) and effective refractory period (ERP) APD APD ERP
Resting Activated Inactivated Extracellular Nat m( 40 40 0 8-40 Threshold 三60 Recover A schematic representation of Nat channels cycling through different conformational states during the cardiac action potential. Transitions between resting, activated, and inactivated states are dependent on membrane potential and time. the activation gate is shown as m and the inactivation
A schematic representation of Na+ channels cycling through different conformational states during the cardiac action potential. Transitions between resting, activated, and inactivated states are dependent on membrane potential and time. The activation gate is shown as m and the inactivation
A. Electrophysiological basis of arrhythmias 0 2. Slow and fast response cells u slow response cells: pacemaker cells u fast response cells: conduction and contraction cells Fast response Slow response phase 4 potential -90 mV 70 mv depolarization Na,, 120 m V, 1-2 ms Ca+, 70 mV,7ms automaticity low(0.02 V/s) high(0.1 V/s) conduction fast( 200-1000 V/s) slow( 10 V/s) effects conduction icemaker
2. Slow and fast response cells slow response cells: pacemaker cells fast response cells: conduction and contraction cells Fast response Slow response phase 4 potential －90 mV －70 mV depolarization Na+ , 120 mV, 1-2 ms Ca2+, 70 mV, 7 ms automaticity low（0.02 V/s） high（0.1 V/s） conduction fast（200-1000 V/s） slow（10 V/s） effects conduction pacemaker A. Electrophysiological basis of arrhythmias
0「窦房结 Slow response 40H0 膜 心室 电 2 Fast response 0 0 位 4 V)-90 Action potentials of slow and fast response cells
Action potentials of slow and fast response cells Slow response Fast response
Interatrial sinoatrial(SA)node (AV) node Threshold potental Faster rate of Internodal Len depolarization branch Time (msec) br△nch atrioventricular(Av) node ventricle Threshold Slower rate depolarization Time(mse Slow response pacemakers in sinoatrial (SA) node and atrioventricular (AV) node
Slow response pacemakers in sinoatrial (SA) node and atrioventricular (AV) node sinoatrial (SA) node atrioventricular (AV) node
