Sudden Cardiac Death

Question 1

Where do most episodes of SCD occur?

Answer 1

Home

Public: better chance of survival
More common in lower socioeconomic profile
M>F
45-50yo

Question 2

The likely rhythm in IHCA patient with HF

Answer 2

Ventricular fibrillation

also MC initial rhythm in OHCA in public

Suggests that ACS is the cause
present in only 23% of all cardiac arrests

outcome is strongly influenced by initial rhythm

Question 3

Most SCD and MI occur when?

Answer 3

First few hours of awakening

Due to:
1. circadian pattern
2. increased sympathetic stimulation (hence, B blockers provide protection CAD/LEF patients)

Question 4

Enumerate the Hereditary Channelopathies (5)

Answer 4

1. Brugada syndrome
2. Early repolarization syndrome (ERS)
3. Long QT syndrome (LQTS)
4. Short QT syndrome
5. Catecholaminergic polymorphic ventricular tachycardia (CPVT)

Question 5

Major cause of SCD

Answer 5

Coronary Artery Disease

80% of SCD victims

followed by Cardiomyopathy

Question 6

Best available predictor of SCD risk

Answer 6

Severe left ventricular dysfunction with reduced ejection fraction

< or = to 35% = primary candidates of implantable cardioverter-defibrillator

Question 7

Remarks of NYHA Class in terms of risk of death

Answer 7

NYHA 2 & 3= Higher risk of death due to SCD than Pump failure
NYHA 4 = Higher risk of death due to Pump failure

symptoms at:
2 - moderate exertion
3 - mild exertion
4 - rest

Question 8

Candidates for implantable cardioverter-defibrillator (7)

Answer 8

1. Prior documented cardiac arrest
2. Vfib
3. Vtach (Hemodynamically sustained or non-sustained)
4. 1st degree relative with SCD
5. 1 or more episode of unexplained syncope (including children)
6. LV wall >or= 30mm (massive LVH)
7. Abnormal Exercise BP + any of above

Question 9

T-Wave inversions in the right precordial leads (V1-3) suggests?

Answer 9

Arrythmogenic right ventricular cardiomyopathy

Right sided HF
Treatment: Implantable cardioverter-defibrillator
Anti-arrythmics have no role

Question 10

Most common Coronary Artery Anomaly associated with SCD

Answer 10

Anomalous Origin of Left Coronary Artery from Pulmonary Artery Syndrome

Left coronary artery traverses aorta and main pulmonary artery

Dx: CT or MRI
Ischemia, Arrythmia, SCD are triggered during exercise due to increasing venous return -> dilates main pulmonary artery -> compresses anomalous coronary artery
Tx: surgery

Question 11

Greatest risk of SCD in children and adults with congenital heart disease with what characteristic?

Answer 11

Left heart obstructive lesions

Aortic stenosis, Aortic Coarctation
Cyanotic defects (Ebstein’s, Corrected TGA, TOF)

Most deaths of occur during exercise (Vifb)

Nonventricular arrythmia can still be present after sx(w/c is the mainstay)

Question 12

Typical finding in hemodynamically significant Aortic Stenosis

Answer 12

Harsh late peaking systolic murmur at the upper right sternal border with radiation to the neck

Effort induced dyspnea, MI, Vent arrythmia triggers syncope and SCD

MC:
1,. Congenitally bicuspid aortic valve cacifies and narrows on adulthood
2. Calcification of tricuspid aortic valve
3. in 70-80yo

Question 13

Degeneration of SA node + disorder in conduction tissue beteween SA and AV node and the AV node itself

Answer 13

Sinus Sick Syndrome

Lightheadedness, Syncope, SCD
Tx: Pacemaker
Lenegre’s disease = Idiopathic sclerodegeneration of AV node and bundle branches
Lev’s disease = Invasion of conduction system by fibrosis or calcification spreading from adjacent cardiac structures

Question 14

Define Sudden Arrythmia Death Syndrome

Answer 14

Sudden cardiac death occuring out of hospital often during sleep or rest without any premonitory symptoms and no anatomic abnormality on autopsy

relatively young adults
mostly men
no symptoms including syncope

Question 15

What can be identified through Cardiovascular and Genetic examination of 1st degree relatives

Answer 15

Ion channel disease

Question 16

Brugada Syndrome ECG

Answer 16

Prominent J-Wave + Downsloping ST-segement elevation in ECG at V1-V3

Commonly affects men
Resembles RBBB
Autosomal dominant
High risk SCD

Common is SEA -unexplained nocturnal death syndrome
PH - bangungut
Japan - Pokkuri
Thailand - Lai Lai

Prevention:cardioverter-defib placement

Question 17

Brugada Pathophysiology

Answer 17

Total loss of Na channel
or

acceleration of recovery from Na channel activation

Question 18

Early Depolarization Syndrome

Answer 18

Prominent Notch like J wave on QRS downslope followed by upsloping ST Segment elevation + reciprocal ST-segment depression in aVR

Rare
Mostly in males and athletes
Benign variant of normal ventricualr depolarization
To normalize: exercise/rapid ventricualr pacing

Question 19

Effect of drugs on early depolarization syndrome

Answer 19

Na channel blockers and B blockers: Increases ST elevation

Isoproterenol or mild exercise decreases ST elevation

Question 20

Characterize Long QT syndrome

Answer 20

1. Prolonged Corrected QT interval
2. Syncope
3. SCD by Torsade de pointes and Vfib

Prolonged QT is due to dispersion in ventricular repolarization

Hereditary (recessive; Jervell and Lange-Nielsen syndrome w nerve deafness)

Acquired (HYPO- K/Mg /Ca, ischemia, anorezia, CNS pathology, levofloxacin, terfenadine-ketoconazole, antipsycotic or antiarrythmics)

Question 21

Bazett’s equation

Answer 21

QT = QTm / √ R-R

QTm - measured QT in seconds; R-R - interval bet 2 cons R waves

Normal QT 0.35 to 0.44s

Question 22

Management of Long QT syndrome (5)

Answer 22

1. Avoidance QT prolonging drugs
2. Avoidance of high intensity sports
3. Cardio/electrophysio referral
4. B-blockers for prophylaxis vs SCD
5. Implantable cardioverter-defibrilator

Question 23

Short QT syndrome

Answer 23

<0.34

still corrected

Due to HYPER-Ca/K, Acidosis, SIRS, MI, Inc vagal tone, Autosmal genetic pattern

vfib, syncope, polymorphic vtach, SCD

Inferolateral leads

Prophylaxis: B-Blocker
Cardioverter-defibrilator candidate

Question 24

In this hereditary channelopathy, most are diagnosed with epilepsy

Answer 24

Catecholaminergic Polymorhpic Ventricular Tachycardia

Defective myocardial cellular calcium handling

Prophylaxis: B-Blocker
Cardioverter-defibrilator candidate

Question 25

Most common premonitory symptoms of SCD (3)

Answer 25

1. Chest discomfort
2. Dyspnea
3. “Not feeling well”

Best prevention: recognize signs and symptoms that place the patient at higher risk, admit then refer

Question 26

Best Prevention for SCD

Answer 26

Implantable cardioverter-defibrillator in high risk patients

2nd line: B-blockers, Sotalol, Amiodarone

HR: Resuscitated Vifb or cardioverted our of sustained ventricular tachycardia

Question 27

Findings of Cardiac Arrythmia Suppresion Trial

Answer 27

Class I Na channel blockers are PROARRYTHMIC and INCREASE ODDS of SCD

Encainide, Flecainide, Moricizine

Question 28

Most effective means to rescue patients from SCD

Answer 28

EMS
In hospital resus systems

Question 29

Likelihood of SCD survial is high if: (3)

Answer 29

1. Initial Rhythm is Vtach or Vfib (corase Vfib)
2. Witnessed arrest
3. Prompt CPR and eary defib is provided

if not the above initial rhythm: survival is <5%
Unwitnessed asystole rarely survives hospital discharge neurologically intact unless there is a reversible cause or increased vagal tone