biventricular pacing
DESCRIPTION
BIVENTRICULAR PACING. Zhu Yi ;Bai Lu; Jin Xingxing; Gu Hangyu; Pan Lingxiao ; Li Ran. Agenda. Case Report The Clinical Problem Background Knowledge Pathophysiology of LBBB Operation of CRT Mechanism of CRT Clinical Uses of CRT Adverse Effects Combine with CCM. Case Report. - PowerPoint PPT PresentationTRANSCRIPT
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BIVENTRICULAR PACING
Zhu Yi ;Bai Lu; Jin Xingxing; Gu Hangyu;
Pan Lingxiao ;Li Ran
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Agenda• Case Report• The Clinical Problem• Background Knowledge• Pathophysiology of LBBB• Operation of CRT• Mechanism of CRT• Clinical Uses of CRT• Adverse Effects• Combine with CCM
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Case Report
• A 55-year-old man.• An anterior-wall myocardial infarction, 6 m ago.• Persistent shortness of breath with mild exertion, 3
m ago.• An exacerbation of congestive heart failure.• ECG: sinus rhythm, left bundle-branch block.• UCG: left ventricular ejection fraction of 25%.• Current treatment: furosemide, lisinopril, and
carvedilol.
• Further treatment: implantation of a biventricular pacemaker????
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The Clinical Problem
• 1/4 ~ 1/3 heart failure have left bundle-branch block.
• Left bundle-branch block causes a poorer prognosis.
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Background Knowledge
Regular cardiac output needs:
I. Electrical synchrony
II. Mechanical contractibility of cardiac muscle cells
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How to achieve electrical synchronization?
I. Conductive pathway: sinus node internodal tract A-V node
bundle of His left and right bundle-branches Purkinje fiber
To assure:① Synchronization of left and right
ventricles② Coordination of atrium and
ventricles
II. Intercalated disc
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Velocity of Conduction (m/
s)
SA node 0.1~0.2
Atrial 0.3~0.5
AV node 0.05~0.1
His Bundle 0.8~1.0
Purkinje Fibres* 2.0~5.0
Ventrcular* 0.3~0.5
Cardiac Conduction SystemCardiac Conduction System
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Pathophysiology Of LBBB
• LBBB altered depolarization: Anterior septum inferior & lateral left wall
• Dyssynchronous contraction: Interventricular septum left free wall
• Inefficient contraction: Decrease of LVEF & CO
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Cardiac Conduction System & Biventricular Pacing
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Block of Conductive pathway leads to:
Ⅰ . Systole period: Synchronization↓ Strength↓ CO/CI↓ LVEF↓
Ⅱ . Diastole period: Coordination↓ A-V Filling Uncooperate Inadequate Blood Filling LVEF↓
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Left Bundle Branch Block
• Organic Cardiopathy
• ECG:Sinus rhythm
Left deviation axis
QRS≥0.12s(Complete)
V1、 2 Leads:QS type
V5、 6 Leads: R type
ST-T Segment: Secondary Alteration
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ECG Of Left Bundle Branch Block
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Operation of CRT-----Pacemaker and Leads
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Operation of CRT ---- Standard Approach of Leads
• Inserted pacing lead into mouth of the coronary sinus
• Advanced posteriorly around the atrioventricular-valve ring
• Passed into a venous branch running along the free wall of the left ventricle
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Biventricular Pacing for CRT
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Mechanism Of CRT
• Stimulate R & L ventricles; R atrium is also paced.
• Eliminate left wall delay.• Shorten QRS complex.• LV pressure rise rate↑ , pulse pressure↑
, stroke work↑ , CO/CI↑ , PCWP(LV function) ↓
• Not restore normal pattern.• Re-built a physiological mechanical pattern through
a fixed electrical pattern.
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Effect Summary of CRT
• Improve ventricular function
• Not increase myocardial consumption
• Reverse ventricular remodeling
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Clinical Use ---- Indications
• Dilated cardiomyopathy (ischemic or non-ischemic)
• LVEF ≤ 35%• QRS interval ≥ 120 msec• NYHA class III or IV despite optimal
medical therapy (Loop diuretics, BB, ACEI, ARB)
• Implantation of both CRT & CVD
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Clinical Use -- Contraindications
• Increased risks of bleeding• Infection• Life-limiting medical condition• Heart failure requires parenteral
inotropic therapy
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Adverse Effect -- Implantation
• Mutation-induced inability to implant LV lead
• Uncomfortable diaphragmatic stimulation – Hiccup
• Coronary-sinus dissection• Coronary-vein or -sinus perforation
– tamponade• Pneumothorax, complete heart
block, and asystole
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Adverse Effect – Post-Op
• Dislodgment of the LV lead• Infection of the device
(Pacemaker pocket)• Atrial arrhythmias• External electromagnetic fields
interference (MRI, cell phone, power cable, electrical motor, electrocautery, radiation…)
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Combine with CCM
I. CCM---- cardiac contraction modulating:
modulate Calcium current stimulate CMC in refractory period increase CMC contractibility directly
II. CRT---- cardiac resynchronization therapy:
assure synchronization
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我们可以用赞叹的手臂拥抱一千条银河,但当那灿烂的光流贴近我们的前胸,最动人的音乐仍是一分钟六十次雄浑坚实如祭鼓的人类的心跳!
医生不是生命的创造者--他是协助生命神迹保持其本然秩序的人!