Ischaemic heart disease Flashcards
Classify the risk factors for IHD
Fixed
- Age
- Male Sex
- Positive family history
Modifiable
- Hyperlipidaemia
- Smoking
- Diabetes
- Hypertension
How do Long-acting nitrates treat IHD
reduces venous return and diastolic pressure, which in turn reduces the impedence to left ventricular emptying and relaxes coronary artery tone
List 3 non-pharmacological treatments for IHD
Percutaneous Transluminal Coronary Angioplasty (PCTA)
Coronary Stents (bare metal or drug eluting)
CABG
What are the pros and cons of RA versus GA in IHD
RA
PROS
- Reduced SNS response during intubation and extubation (as in GA)
CONS
- Excessive hypotension –> ischaemia
GA
PROS
- VA may improve myocardial O2 demand:supply
CONS
- SNS during intubation and extubation (attenuated using opioids/beta blockers
Describe the use of induction agents in IHD
Propofol and thipoental both cause a drop in BP, and although it may be difficult to distinguish between the two, propofol is likely to cause the greatest drop, especially if not given slowly.
Etomidate is least likely to cause hypotension, but its use is declining due to concerns over adrenal suppression.
Ketamine is relatively contraindicated because of the sympathomimetic effects which increase oxygen demand.
Which volatile agent has been associated with coronary steal phenomenon and what is this phenomenon
Isoflurane
VD of normal coronary vessels diverting blood away from diseased ones
Avoided in IHC
How can Desflurane be deleterious to a patient with IHD
At MAC >1.5 or with rapid increase of inspired concentration - sympathomimmetic effects
Describe the relevant influence of common muscle relaxants on a patient with IHD
Atracurium - H release with mild drop in BP
Rocuronium - Mild tachycardia
Vecuronium - nil
Sux - Muscle contraction –> transient increase in VR
Classify the causes of hypertension
Essential (90% of cases)
Secondary (10% of cases)
- Renal
- Endocrine
- Neurogenic
- Others
What are the renal causes of secondary hypertension
Renal artery stenosis
Polycystic Kidney Disease
Chronic Renal Failure
Glomerulonephritis
What are the endocrine causes of secondary hypertension
Primary hyperaldosteronism Phaeochromocytoma Cushing's Syndrome Acromegaly Hyper/hypothyroidism Exogenous hromonses (steroids/OCP)
What are the neurogenic causes of secondary hypertension
RICP
What are the other causes of secondary hypertension
White coat HPT Isolated systolic hypertension (elderly - calcified atherosclerosis) Sleep apnoea Pre-eclampsia Coarctation of the aorta Hypercalcaemia Hypercapnoea Porphyria
Describe how hypertension causes heart disease
Increased afterload –> LV hypertrophy –> Reduced LV compliance –> increased LVEDP –> increased LAP –> atrial fibrillation and mitral valve incompetence
LVH –> imbalanced O2 supply/demand –> remodelling –> systolic dysfunction –> reduced RBF –> activation RAAS –> salt and fluid retention.
How can myocardial ischaemia occur in the absence of coronary artery disease in the context of hypertension
Hypertrophied myocardium and afterload –> increased demand
High intramural pressure –> compromised blood and O2 supply
Should a patient with uncontrolled stage 1/2 HPT be cancelled?
It is generally agreed that patients presenting with BP <180/110 mmHg (stages 1 and 2) are not at increased risk of perioperative cardiac complications. Therefore, surgery can proceed.
However, it is important that the patient’s blood pressure is monitored very closely intraoperatively and that it is maintained within 20% of their baseline readings.
Should a patient with uncontrolled stage 3 HPT be cancelled?
For patients who present with stage 3 hypertension (BP >180/110 mmHg), the possible benefits in delaying surgery in order to control the hypertension must be considered in relation to the risks of doing so.
Even in severe hypertension, there is little evidence for delaying surgery. However, this is an area of controversy and it warrants discussion with a consultant anaesthetist.
