Sudden Cardiac Death

Question 1

Whats normal range of QT interval

Answer 1

Any reading above 444ms - look up

Women > 460
Men > 450

Represents heart contract and relax.

Question 2

Whens prolonged QT

Answer 2

Prolonged QT in hypocalcemia
Shortened QT in hypercalcemia

Hyperkalemia - nah

Prolong QT - torsades de pointes (polymorphic VT) - asynch shock (defib)

Question 3

Long QT syndrome, which channel defect

Answer 3

Potassium channels defect, causing delayed REpolarization

Question 4

LQTS causes

Answer 4

Congenital :
Jervel Lange Nelson syndrome (deafness)
Romano ward syndrome (no deafness)

Electrolytes:

Hypocalcemia
Hypomagnesemia
Hypokalemia

Drugs:
Anti psychotics: haloperidol
Anti histamine: terfenadine
SSRI antidepressants
Tricyclic anti depressants
Antibiotics : erythromycin
Antisickness : ondansetron
Anti chronic pain: Methadone
Anti malarial : chloroquine

Question 5

Other causes of LQTS

Answer 5

1- Acute MI,
myocarditis

2- Subarachnoid Hemorrhage - massive adrenaline rush due to irritation of hypothalamus (HPA-axis response)

3- Hypothetmia

Question 6

How does SAH irritate the hypothalamus causing LQTS

Answer 6

Subarachnoid hemorrhage (SAH) irritates the hypothalamus because the blood in the subarachnoid space spreads around the brain and comes into direct contact with structures near the base of the brain, including the hypothalamus. Here’s how this happens:
1. Anatomy of the Subarachnoid Space:
• The subarachnoid space surrounds the brain and is filled with cerebrospinal fluid (CSF).
• The hypothalamus lies near the base of the brain, close to the circle of Willis and large blood vessels prone to aneurysms (a common cause of SAH).
2. Release of Blood and Inflammatory Substances:
• When a blood vessel ruptures in SAH, blood enters the subarachnoid space, spreading over the brain’s surface.
• This blood contains substances like hemoglobin and breakdown products that irritate nearby brain tissues.
3. Impact on the Hypothalamus:
• The hypothalamus is sensitive to irritation from blood, inflammatory molecules (e.g., cytokines), and increased intracranial pressure.
• The hypothalamus plays a key role in regulating the stress response via the hypothalamic-pituitary-adrenal (HPA) axis and autonomic nervous system.
• This irritation overstimulates the hypothalamus, triggering excessive release of catecholamines (stress hormones like adrenaline) from the adrenal glands.
4. Resulting Catecholamine Surge:
• The catecholamine surge leads to cardiac and systemic effects, such as arrhythmias, neurogenic stunned myocardium, and QT interval prolongation.

In Summary:

Blood from SAH irritates the hypothalamus because it directly bathes this region in the subarachnoid space and activates its stress-regulating functions, causing an exaggerated stress response.

Question 7

Brugada syndrome , which channel defect

Answer 7

Sodium channel

Question 8

Brugada ECG changes

Answer 8

ST-segment elevation in leads V1-V2 with a partial right bundle branch block pattern.

Question 9

Brugada ECG changes

Answer 9

ST-segment elevation in leads V1-V2 with a partial right bundle branch block pattern.

Question 10

Sudden cardiac death

Answer 10

ARVC - fatty and scar myocardium
Brugada - sodium
Long QT syndrome 1 & 2 : potassium
HOCM - beta-myosin heavy chain protein