no slide · pdf filerhythm: see next slide. 3 87-year-old woman: ... •medications:...
TRANSCRIPT
1
Bradyarrhythmia
Ass. Prof. Tomon Thongsri, MD
Buddhachinaraj Phitsanuloke Hospital
2
Case Scenario
An 87-year-old woman reports feeling weak
and short of breath for 2 hours while
walking short distances. She feels exhausted
moving from the car to the ED stretcher.
On physical exam she is pale and sweaty;
HR = 35 /min; BP = 90/60 mm Hg;
RR = 24 /min.
Rhythm: see next slide.
3
87-Year-Old Woman: Symptomatic Bradycardia
Identify A, B, and C
Which one is most likely
to be her rhythm? A
B
C
4
Rhythms to Learn
Sinus bradycardia
Sick sinus syndrome
AV blocks
• 1st degree
• 2nd degree type I
• 2nd degree type II
• 3rd degree
5
Cardiac Conduction System
Primary pacemaker
• Sinus node
• 60-100 /min
Escape pacemakers
• AV node (junction)
• 40-60 /min
• Ventricular
• 20-30 /min
Role of cardiac role
1. จุดก ำเนิดไฟฟ้ำท่ีปล่อยเร็วกวำ่ยอ่มชนะและกดจุดท่ีปล่อยชำ้กวำ่ 2. จุดต่ำงๆ บนเสน้ทำงน ำกระแสไฟฟ้ำสำมำรถปล่อยกระแสฟ้ำได ้3. จุดก ำเนิดไฟฟ้ำยิง่อยูต่ ่ำยิง่ปล่อยชำ้ 4. จุดก ำเนิดไฟฟ้ำยิง่อยูต่ ่ำ QRS ยิง่กวำ้ง
6
7
Cardiac Conduction System
Primary pacemaker
• Sinus node
• 60-100 /min
Escape pacemakers
• AV node (junction)
• 40-60 /min
• Ventricular
• 20-30 /min
8
9
Case Scenario
An 87-year-old woman reports feeling weak
and short of breath for 2 hours while
walking short distances. She feels exhausted
moving from the car to the ED stretcher.
On physical exam she is pale and sweaty;
HR = 35 /min; BP = 90/60 mm Hg;
RR = 24 /min.
Rhythm: see next slide.
What is the rhythm?
87-Year-Old Woman: Symptomatic Bradycardia
What is the rate?
• Approximately 35 beats per minute
What is the rhythm?
• Is it regular : yes
• Is there a p wave before every QRS and vice versa? : yes
• P wave come from sinus node? : yes
P wave of sinus : + in I, II, III, aVF, regular
P from sinus node
12
P wave of sinus : + in I, II, III, aVF, regular
Sinus Bradycardia
Sinus Bradycardia
Sinus rhythm with a resting heart rate of 60
beats/minute or less
actually become symptomatic until
HR < 50 beats/minute
History:
• most often asymptomatic
• Symptom:
– Syncope
– Dizziness
– Lightheadedness
– Chest pain
– Shortness of breath
Sinus Bradycardia
Physical examination:
• Cardiac auscultation and palpation of peripheral pulses reveal : slow, regular heart rate.
• The physical examination : nonspecific
– Decreased level of consciousness
– Cyanosis
– Peripheral edema
– Pulmonary vascular congestion
– Dyspnea
– Poor perfusion
– Syncope
Sinus Bradycardia
– Physiologic causes : increased vagal tone
eq. bradycardia in athletes
vomitting
Causes: Sinus Bradycardia
Pathologic Causes: • most common : sick sinus syndrome.
• Medications:
– digitalis glycosides, beta-blockers
– calcium channel-blocking agents
• Medications: antiarrhythmic drug class I and amiodarone.
• toxins :
– lithium, paclitaxel, toluene, dimethyl sulfoxide (DMSO)
– topical ophthalmic acetylcholine
fentanyl, alfentanil, sufentanil, reserpine
– clonidine.
Sinus Bradycardia
Pathologic Causes (cont.):
• Inferior wall MI
• Electrolyte imbalance: hyperkalemia
• hypothermia, hypoglycemia, hypothyroidism
• sleep apnea
• Increase intracranial pressure
• Less commonly:
– diphtheria
– rheumatic fever
– viral myocarditis.
Sinus Bradycardia
Sick Sinus Syndrome
• Involves a dysfunction in the ability of the sinus node to generate or transmit an action potential to the atria
• signs and symptoms :
– cerebral hypoperfusion, in association with
sinus bradycardia,
sinus arrest,
sinoatrial (SA) block,
carotid hypersensitivity
or alternating episodes of bradycardia and tachycardia
Sinus arrest
Sino-atrial block
Sino-atrial block
Sick Sinus Syndrome
• Involves a dysfunction in the ability of the sinus node to generate or transmit an action potential to the atria
• signs and symptoms :
– cerebral hypoperfusion, in association with
sinus bradycardia,
sinus arrest,
sinoatrial (SA) block,
carotid hypersensitivity
or alternating episodes of bradycardia and tachycardia
Sick sinus syndrome
• Most commonly occurs in elderly patients with
concomitant cardiovascular disease and follows an
unpredictable course.
• The majority of cases remain idiopathic.
26
Case Scenario 2
An 87-year-old woman reports feeling weak
and short of breath for 2 hours while
walking short distances. She feels exhausted
moving from the car to the ED stretcher.
On physical exam she is pale and sweaty;
HR = 35 bpm; BP = 90/60 mm Hg;
RR = 18 rpm.
Rhythm: see next slide.
27
What Is This Rhythm?
28
What Is This Rhythm?
29
First degree AV Block
• Definition:
– Prolongation of the PR interval > 200 msec ( 5 ช่องเลก็) • Pathophysiology:
– Every atrial impulse is transmitted to the ventricles, resulting in a regular ventricular rate.
– Can arise from delays in the conduction system in the AV node itself (most common), the His-Purkinje system, or a combination of both.
• Mortality/Morbidity: – In and of itself, first-degree AV block is a benign condition, with no
associated increase in morbidity or mortality.
• Treatment – Define causes : drug overdose, acute MI, myocarditis, degenerative
– No treatment indicated if asymptomatic.
First degree AV Block
31
What Is This Rhythm?
32
What Is This Rhythm?
P P P P P P P P
33
Second Degree AV Block Type I
34
What Is This Rhythm?
35
What Is This Rhythm?
P P P P P P
36
Second Degree AV Block Type II
Second degree AV block
• Refers to a disorder of the cardiac conduction system in which some atrial impulses are not conducted to the ventricles.
• Electrocardiographically, some P waves are not followed by a QRS complex
Mobitz I • Characterized by a progressive prolongation of the PR interval, which
results in a progressive shortening of the R-R interval. Ultimately, the atrial impulse fails to conduct, a QRS complex is not generated, and there is no ventricular contraction.
Mobitz II • Characterized by an unexpected nonconducted atrial impulse. Thus, the
PR and R-R intervals between conducted beats are constant.
Pathophysiology: • Mobitz type I block
– Caused by conduction delay in the AV node in 72% of patients and by conduction delay in the His-Purkinje system in the remaining 28%.
• Mobitz type II block – Conduction delay occurs infranodally. The QRS complex is likely to be wide,
except in patients where the delay is localized to the bundle of His.
Mortality/Morbidity: • Mobitz type I second-degree AV block localized to the AV node
– Not associated with any increased risk of morbidity or death, in the absence of organic heart disease.
– No risk of progression to a type II second-degree block or complete heart block exists.
– When a Mobitz type I block occurs during an acute myocardial infarction, mortality is increased.
• Mobitz type II block – risk of progressing to complete heart block
– increased risk of mortality.
Second degree AV block
Causes:
• Mobitz I block – high vagal tone: athletes or young children.
– structural heart disease : tetralogy of Fallot
– valvular surgery (especially mitral valve).
– myocardial infarction (especially inferior wall)
– drug induced : beta-blockers, calcium channel blockers, amiodarone, digoxin, and possibly pentamidine)
• Mobitz II block – most commonly : AMI (anterior or inferior wall)
– Drug-induced
– degenerative
Second degree AV block
40
What Is This Rhythm?
41
What Is This Rhythm?
P P P P P P P
42
Third Degree AV Block Type III
Third degree AV Block
• Disorder of the cardiac conduction system where there is no conduction through the AV node.
• Complete disassociation of the atrial and ventricular activity exists.
• Ventricular escape mechanism can occur anywhere from the AV node to the bundle-branch Purkinje system.
• QRS complexes being conducted at their own rate and totally independent of the P waves.
Third degree AV Block
Mortality/Morbidity:
• Frequently hemodynamically unstable
• The patient may experience syncope, cardiovascular collapse, or death.
History:
• Complete heart block has a wide range of clinical presentations; most patients are symptomatic.
• Patients occasionally are asymptomatic or have only minimal symptoms related to hypoperfusion.
• symptoms include the following:
– syncope
– Fatigue
– Dizziness
– Impaired exercise tolerance
– Chest pain
Third degree AV Block
Physical: • Notable for bradycardia, which can be quite severe.
• Signs of congestive heart failure as a result of decreased cardiac output may be present and include the following:
– Tachypnea or respiratory distress
– Rales
– Jugular venous distention
• Patients may have signs of hypoperfusion, including the following: – Altered mental status
– Hypotension
– Lethargy
• In patients with concomitant myocardial ischemia or infarction, corresponding signs may be evident on examination:
– Signs of anxiety such as agitation or unease
– Diaphoresis
– Pale or pasty complexion
– Tachypnea
Third degree AV Block
Causes:
• congenital vs acquired
Congenital
• Block at the level of the AV node
• asymptomatic at rest but symptoms on exert
because the fixed heart rate
• In the absence of major structural abnormalities, congenital heart block is often associated with maternal antibodies to SS-A (Ro) and SS-B (La).
Complete AV Block
Acquired • Drug induced : beta-adrenergic, and calcium channel
blocking agents.
• Drugs or toxins – Class Ia : quinidine, procainamide, disopyramide
– Class Ic : flecainide, encainide, propafenone
– Class II : beta-blockers
– Class III : amiodarone, sotalol, dofetilide, ibutilide
– Class IV : calcium channel blockers
– Digoxin or other cardiac glycosides
Complete AV Block
Acquired
• degenerative • Infection:
– Lyme carditis
– acute rheumatic fever
• Metabolic disturbances : severe hyperkalemia • Ischemia
– MI - Anterior wall MI can be associated with an infra-nodal AV block.
– < 10% of cases of acute inferior MI and often resolves within hours to a few days.
49
Differentiation of Second- and Third-degree AV Blocks
More P’s than QRSs
PR fixed?
no
QRSs that look alike regular?
no
yes
yes
yes
2nd-degree AV block Fixed
Mobitz II
3rd-degree AV block
2nd-degree AV block Variable Mobitz I
Wenckebach
51
Case Scenario
An 87-year-old woman reports feeling weak
and short of breath for 2 hours while
walking short distances. She feels exhausted
moving from the car to the ED stretcher.
On physical exam she is pale and sweaty;
HR = 35 bpm; BP = 90/60 mm Hg;
RR = 18 rpm.
Rhythm: see next slide.
52
What Is This Rhythm?
53
Junctional bradycardia
54
Case Scenario
An 87-year-old woman reports feeling weak
and short of breath for 2 hours while
walking short distances. She feels exhausted
moving from the car to the ED stretcher.
On physical exam she is pale and sweaty;
HR = 35 bpm; BP = 90/60 mm Hg;
RR = 18 rpm.
Rhythm: see next slide.
55
What Is This Rhythm?
56
What Is This Rhythm?
EKG Changes
EKG Changes Widening of QRS Complex
EKG Changes Ventricular Tach/Torsades
Treatment
1 Stabilize myocardial membrane
• 10%calcium gluconate 10 ml IV push
2 Drive extracellular potassium into the cells
• 2 Agonists (albuterol) 5 ml nebulizer
• 50% glucose 50ml + RI 10 u IV push
• 7.5% NaHCO3 1 amp IV push
3 Removal of Potassium from the body
• Loop diuretic, kayexalate, hemodialysis
BREAK TIME
61