Summary Summar of BNF chapter - Cardiovascular system

CARDIOVASCULAR NOTES – BNF Chapter 2



2.1 POSITIVE INOTROPIC DRUGS

Definitions:

1. Positive Inotropic Drugs – Stimulate heart muscle contractions and cause the
heart rate to increase.
2. Negative Inotropic Drugs – Reduce heart muscle contractions and cause the
heart rate to decrease.
3. Arrythmias – Any deviation from the normal rhythm of the heart
4. Supraventricular Tachycardia – A fast heart beat stemming from an abnormal
area of the atria, it may be so fast that it reduces the pumping efficiency of the
heart.
5. Atrial fibrillation – Rapid and irregular heart and pulse rates caused by
disorganised electrical activity. Symptoms: Breathlessness, reduced exercise
tolerance, angina, palpitations and dizziness. Causes: Hypertension and
ischaemic disease.

2.1.1 Cardiac Glycosides

 Cardiac Glycosides increase the force of contraction of the myocardium and
reduce conductivity within the AV node.
 Cardiac glycosides are most useful in treating supraventricular tachycardias
(particularly atrial fibrillation and atrial flutter).


Cardiac Glycosides

DRUG INDICATIONS SIDE EFFECTS NOTES


Digoxin  Heart Failure  Nausea  Has a long half life.
and  Supraventricular  Vomiting  Renal function is important
Digitoxin arrythmias (atrial  Diarrhoea determinant of dosing for digoxin.
fibrillation/artial flutter  Dizziness  Special care in elderly who may be
 Blurred or particularly susceptible to digitalis
yellow vision toxicity.
 Rash  Hypokalaemia predisposes the
patient to digitalis toxicity. Can be
managed by giving potassium
sparing diuretic or potassium
supplements.
 Digitalis Toxicity can be suspected if
patient develops nausea, vomiting,
diarrhoea, confusion or blurred vision.
Symptoms are SLOW and SICK.
 DIGIBIND = digoxin specific antibody
fragments indicated for digoxin
overdose or strongly suspected
toxicity.




1

, 2.2 DIURETICS

Definitions:

Diuretic – Drugs that increase the volume of urine produced by promoting the
excretion of water and salts from the kidneys. They increase the flow of urine.

For Hypertension: People younger than 55 years and Caucasians respond better to an
ACE inhibitor or Angiotensin II Receptor Antagonists. People aged over 55 years and
afro-Caribbean first line treatment is thiazide diuretics or calcium channel blockers.


2.2.1 Thiazide and Thiazide Related Diuretics:
DRUG INDICATIONS SIDE EFFECTS NOTES


Bendroflum  Oedema  GI disturbance  Moderately potent diuretic.
ethiazide (mild to  Postural hypotension  Inhibit sodium reabsorption at the
moderate  Hypokalaemia beginning of the distal convoluted
heart failure)  Hyponatraemia (low tubule.
 Hypertension sodium in the blood)  They act within 1-2 hours of oral
 Gout administration.
 Altered plasma lipid  Duration of action 12-24 hours.
concentrations  Usually administered in the
 Hypomagnesaemia morning so that diuresis does not
 Hypercalcaemia affect sleep.
 Hyperglycaemia  Continual loss of potassium occurs
 Hyperuricaemia from the body with prolonged use.
 Rare: Impotence Hypokalaemia is dangerous in
severe CVD and in patients treated
with cardiac glycosides.


Indapamide  Essential  GI disturbance  Same as with Bendroflumethiazide
Natrilix Hypertension  Postural hypotension except it is a thiazide related
 Hypokalaemia diuretic.
 Hyponatraemia (low  Indapamine claimed to lower BP
sodium in the blood) with less metabolic disturbance
 Gout particularly less aggravation of
 Altered plasma lipid diabetes mellitus.
concentrations
 Hypomagnesaemia
 Hypercalcaemia
 Hyperuricaemia
 Palpitations




2