Hypertension & Cardiac Failure

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Formula for BP?

BP = Cardiac Output × Total Peripheral Resistance.

Determinants of cardiac output?

Heart rate × Stroke volume.

Baroreceptors location?

Carotid sinus and aortic arch.

Baroreflex response to ↑BP?

↑Baroreceptor firing→↑parasympathetic↓sympathetic→↓HR↓contractility vasodilation.

RAAS sequence?

Renin→Ang I→ACE→Ang II→Aldosterone.

Actions of Ang II?

Vasoconstriction and stimulates aldosterone.

Action of aldosterone?

↑Na+ and water reabsorption→↑ECF→↑BP.

Optimal BP?

Grade 1 hypertension?

140–159/90–99 mmHg.

Grade 2 hypertension?

160–179/100–109 mmHg.

Primary hypertension?

90–95%; no identifiable cause.

Salt-sensitive HTN mechanism?

↑Na retention→↑ECF→↑blood volume→↑BP.

Na/Ca exchanger mechanism in HTN?

↑Intracellular Na→↓Na/Ca exchange→↑Ca in smooth muscle→vasoconstriction→↑TPR.

Major mechanisms contributing to HTN?

↑SNS, ↑Ang II, hyperglycaemia, atherosclerosis, ↑blood viscosity.

Pulmonary hypertension definition?

Mean PAP >20 mmHg at rest.

Formula for PAP?

PAP = CO × PVR + PLA.

Causes of pulmonary HTN?

↑PVR (PE,COPD,hypoxia) or ↑left atrial pressure.

How do pulmonary vessels respond to hypoxia?

They constrict.

Definition of oedema?

Excess interstitial fluid.

PV loop order?

Mitral opens→Mitral closes→Aortic opens→Aortic closes.

Phases of cardiac cycle?

Isovolumetric contraction→Ejection→Isovolumetric relaxation→Filling.

Heart workload formula?

Stroke volume × LV pressure × Heart rate.

Mitral regurgitation causes?

Volume overload→eccentric hypertrophy→LV dilation→left heart failure.

Mechanism of pulmonary oedema in MR?

MR→↑LA pressure→↑pulmonary venous pressure→↑capillary hydrostatic pressure→oedema.

Cause of crackles in HF?

Fluid-filled alveoli reopening.

Cause of dyspnoea in left HF?

Pulmonary oedema impairs gas exchange.

Cause of cyanosis?

Reduced oxygenation.

Why does orthopnoea improve sitting up?

↓Venous return→↓pulmonary blood volume→↓pulmonary oedema.