MOD 4 Flashcards
(29 cards)
What are the chronic risk factors for acute coronary syndromes?
High lipid levels and hypertension.
What are the acute risk factors for acute coronary syndromes?
Transient physiological changes such as a surge in blood pressure and vasoconstriction.
What determines oxygen delivery?
Cardiac Output (CO) × Arterial O₂ Content
What is the formula for cardiac output?
Stroke Volume (SV) × Heart Rate (HR).
Why does the body increase HR and CO?
To increase oxygen delivery to tissues.
What does a high resting heart rate indicate?
A higher risk of mortality.
Why is heart rate prognostic?
It predicts disease development and mortality risk.
Why does high HR increase myocardial oxygen consumption?
It reduces diastolic time and stresses the myocardium.
Why do females often have a higher resting HR than males?
Likely due to lower blood pressure.
How does high HR affect stroke volume and cardiac output?
Less ventricular filling time → ↓ SV → ↓ CO.
How much does a 1 bpm HR reduction reduce death risk?
By 2%.
What’s the effect of a 10 bpm HR reduction?
30% ↓ risk of cardiac death, 39% ↓ sudden cardiac death.
What does a 5 bpm HR increase (above 70 bpm) lead to?
8% ↑ in cardiovascular death risk.
What are long-term effects of high HR?
Arterial stiffness, endothelial dysfunction, and ventricular wall stiffening.
What are short-term effects of high HR?
Increased metabolic demand and worsening ischaemia.
What is arrhythmogenesis?
Abnormal SA node impulse conduction.
Where is the heart located anatomically?
Between the 2nd and 5th intercostal space at the midsternum.
Which artery is usually dominant: left or right coronary?
Left coronary artery (usually).
Left coronary artery (usually).
An action potential from the SA node.
What neurotransmitter decreases HR via the vagus nerve?
Acetylcholine
What is intrinsic heart rate?
100-110 bpm
What is HRV and how is it measured?
Heart Rate Variability, measured using RR intervals.
What does SDNN measure in HRV?
Long-term HR variability (doesn’t indicate PNS or SNS origin).
What does rMSSD measure?
Short-term HR variability due to parasympathetic modulation.
