8/19- Sudden Cardiac Death Flashcards
What are the biggest risk factors for atherosclerosis?
- High cholesterol
- HTN (> 140/90)
- Diabetes
- Smoking (current/recent!)
What are 2 broad diseases that can lead to heart failure?
- Coronary Artery Disease (from Atherosclerosis)
- Valvular Heart Disease
How can CAD (coronary artery disease) present?
- Arrhythmias -> Sudden Cardiac Death
- Angina (stable or unstable)
- Myocardial Infarction
What is included in “Acute Coronary Syndromes”?
- Unstable angina
- Myocardial infarction
T/F: > 1 million people suffer SCD/yr in the US
False
- 1300 cases/d (400,000/yr) in the US
T/F: The most common cause of SCD in adults is asystole
False
The most common cause of SCD in adults is ventricular fibrillation
- Primary VF is the most common cause of out-of-hospital SCD
- Asystole is usually the result of sustained myocardial anoxia during initial episode of VF rather than the primary cause of death
- Asystole is the MCC of SCD in infants
T/F: ASH/IHSS are the most common etiology of SCD in the US
False
- This is the most common etiology in 15-35 yo
- In general, most common cause is CAD
T/F: Most SCD are due to VF complicating AMI
False
T/F: VF without AMI rarely recurs unlike VF with AMI
False
Define: sudden cardiac death (SCD)
Sudden unexpected death due to cardiac causes occurring within one hour after the onset of cardiac symptoms
- NHLBI: death within 24 hrs of Sx
- WHO: un-witnessed death
- Uniformly fatal (unless successfully resuscitated; 1/3 survive)
Define: ventricular fibrillation (VF). What does the ECG look like?
Chaotic and asynchronous electrical ventricular activity arising from multiple foci and spreading erratically throughout the myocardium
Define: asystole (flat line “___”)
Asystole is usually the result of sustained myocardial anoxia during initial episode of VF rather than the primary cause of death
Define: primary vs. secondary VF
Primary VF: no associated MI
Secondary VF: associated MI (as proven by post-mortem changes on autopsy or cardiac enzymes)
What is the public health impact of SCD?
- 1300 cases/d (400,000/yr) in the US
- 50% of all CAD deaths
- 1/3 of all deaths age 20-64
- Gradual decline since 1971 (due to EMS, decreased coronary risk factors, and the coronary care unit)
Which has the higher recurrence: primary or secondary VF?
SCD recurrence is 5-10x higher in primary VF (that not associated with an MI)
- i.e. probably have some kind of factor/tissue very vulnerable to arrhythmias that hasn’t been fixed
Primary vs. Secondary VF:
- 55 yo man presents w/ crushing diffuse anterior chest pain 10/10 with diaphoresis and dyspnea
- No change in ECG or chest pain with SL NTG
What is the pt suffering from?
A. Acute massive viral pericarditis
B. Unstable angina with a “platelet plug”
C. LAD Vasospasm refractory to SL NTG
D. Acute ST elevation MI due to fibrin/RBC “red” clot completely occluding the LAD
E. Intense coronary constriction due to anxiety
ECG: acute anterolateral MI
- Local ST elevation (leads I, aVL, and V2-V5)
- Acute MI likely due to occlusion in the pulmonary artery (?)
What is the pt suffering from?
A. Acute massive viral pericarditis
B. Unstable angina with a “platelet plug”
C. LAD Vasospasm refractory to SL NTG
D. Acute ST elevation MI due to fibrin/RBC “red” clot completely occluding the LAD
E. Intense coronary constriction due to anxiety
Primary vs. Secondary VF (pt 2):
- 55 yo man who presented with chest pain sustains a sudden unexpected cardiac arrest 3-4 hrs later
- How would you manage him after initial resuscitation?
- How likely is recurrent SCD after hospital discharge?
- This was a secondary cardiac arrest (or secondary VF); SCD associated with MI
- Chance of recurrence is low; no need for ICD after discharge
Which of the following best applies to this 55 yo man (with chest pain and unexpected cardiac arrest 3-4 hrs later)?
A. Primary VF
B. Secondary VF
C. Massive anterolateral MI complicated by VF
D. Low risk of recurrent SCD
E. B, C, and D
Which of the following best applies to this 55 yo man (with chest pain and unexpected cardiac arrest 3-4 hrs later)?
A. Primary VF
B. Secondary VF
C. Massive anterolateral MI complicated by VF
D. Low risk of recurrent SCD
E. B, C, and D
What is an AICD? For who is it routinely recommended?
Automatic Implantable Cardioverter Defibrillator (or just ICD)
- Routinely recommended for primary VF (high chance of recurrence); NOT recommended for secondary
What can an AICD do? (Don’t need to memorize)
- Provide shock in cases of ventricular fibrillation (VF)
- ATP- anti-tachycardiac pacing- try to recognize VT before above shock is required (will pace ventricle faster for just a few s in “overdrive pacing”)
What is this?
Ventricular fibrillation
What is the most common cause of SCD?
Tachy-arrhythmias
- Ventricular fibrillation**
- Ventricular tachycardia
- Ventricular flutter
Brady-arrhythmias
- Asystole
- Bradycardia
What is this?
Ventricular Tachycardia (3+ consecutive beats)
What is VT and AIVR? Features?
VT- ventricular tachycardia
AIVR - accelerated idioventricular rhythm
- Both are wide QRS regular tachycardia with no P (but AIVR does not -> SCD)
- VT has a rate >110/min while AIVR is under 110/min; this is the only difference!
Risk of ventricular fibrillation is higher with what?
- Longer VTs > 12 beats
- Faster VTs > 160/min
Which kills, VT or AIVR?
VT!
What is the most common cause of SCD in adults?
Ventricular fibrillation
- Primary VF is the most common cause of out-of-hospital SCD
What triggers an actual episode causing SCD at a particular moment (SCD triggers)?
- PVC with R-on-T
- Coronary reperfusion
- CNS stimulation: sympathetic and vagal activity
- Psychological stress
What is the significance of a sympathetic activity as SCD “trigger”?
BB prevent VF post-MI
CAD is a responsible for __% of all SCD
CAD is a responsible for 80% of all SCD
Etiologies of SCD
CAD (80%!)
Acquired non-coronary heart disease:
- Cardiac tamponade
- Cardiac rupture
- Myocardial disease: IHSS
- Valvular heart disease: AS
- Aortic diseases
*Metabolic imbalance: K, Ca
*Drugs: cocaine, TCA, phenothiazine
You are called to see a pt who just arrest in CCU and has this ECG. What is it?
A. Polymorphic VT
B. Monomorphic VT
C. QT is probably under 360 ms
D. QTc is probably > 440 ms
You are called to see a pt who just arrest in CCU and has this ECG. What is it?
A. Polymorphic VT
B. Monomorphic VT
C. QT is probably under 360 ms
D. QTc is probably > 440 ms
- Polymorphic VT associated with prolonged QT
What is normal rate for QTc?
440 ms
ECG changes for electrolyte imbalances:
- Low Ca
- High Ca
Low Ca: short QT interval
High Ca: long QT interval
Which of the following is the MOST COMMON cause of Long QT?
A. Low K
B. Low Ca
C. Low Mg
D. Low Na
Which of the following is the MOST COMMON cause of Long QT?
A. Low K
B. Low Ca
C. Low Mg
D. Low Na
- We commonly use drugs that lower K (e.g. loop diuretics)
Is the pts age useful in predicting the underlying cause of SCD?
Yes
- CAD is the most common etiology of VF in middle aged and older adults
- IHSS is the commonest cause of SCD in 15-35 yo younger adults
Which valvular abnormality is MOST likely to cause SCD?
A. Mitral stenosis
B. Aortic stenosis
C. Aortic insufficiency
D. Mitral regurgitation
Which valvular abnormality is MOST likely to cause SCD?
A. Mitral stenosis
B. Aortic stenosis
C. Aortic insufficiency
D. Mitral regurgitation
Which cardiomyopathy is MOST likely to cause SCD?
A. Congestive
B. Hypertrophic
C. Restrictive
Which cardiomyopathy is MOST likely to cause SCD?
A. Congestive
B. Hypertrophic
C. Restrictive
Who are appropriate candidates for ICD implantation: secondary prevention?
- Pt surviving cardiac arrest not associated with acute MI or other reversible causes (ischemia, electrolyte/metabolic abnormalities)
- Pt suffering from sustained ventricular tachycardia (without cardiac arrest) associated with structural heart disease (HCM, ARVD, valvular heart disease, congenital heart disease…)
Who are appropriate candidates for ICD implantation: primary prevention?
- Pt with structural heart disease (ischemic or non-ischemic) with severe LV systolic dysfunction with the LVEF under 35%
- Pt with known arrhythmogenic condition and certain high risk features for developing life-threatening arrhythmias (inc. first line family Hx of sudden death)
- LQTS
- Brugada
- HCM
- ARVD
- CPVT
