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Diploma in Anaesthesia > Ischaemic heart disease > Flashcards

Ischaemic heart disease Flashcards

1
Q

Classify the risk factors for IHD

A

Fixed

  • Age
  • Male Sex
  • Positive family history

Modifiable

  • Hyperlipidaemia
  • Smoking
  • Diabetes
  • Hypertension
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2
Q

How do Long-acting nitrates treat IHD

A

reduces venous return and diastolic pressure, which in turn reduces the impedence to left ventricular emptying and relaxes coronary artery tone

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3
Q

List 3 non-pharmacological treatments for IHD

A

Percutaneous Transluminal Coronary Angioplasty (PCTA)
Coronary Stents (bare metal or drug eluting)
CABG

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4
Q

What are the pros and cons of RA versus GA in IHD

A

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

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5
Q

Describe the use of induction agents in IHD

A

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.

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6
Q

Which volatile agent has been associated with coronary steal phenomenon and what is this phenomenon

A

Isoflurane

VD of normal coronary vessels diverting blood away from diseased ones

Avoided in IHC

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7
Q

How can Desflurane be deleterious to a patient with IHD

A

At MAC >1.5 or with rapid increase of inspired concentration - sympathomimmetic effects

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8
Q

Describe the relevant influence of common muscle relaxants on a patient with IHD

A

Atracurium - H release with mild drop in BP
Rocuronium - Mild tachycardia
Vecuronium - nil
Sux - Muscle contraction –> transient increase in VR

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9
Q

Classify the causes of hypertension

A

Essential (90% of cases)

Secondary (10% of cases)

  • Renal
  • Endocrine
  • Neurogenic
  • Others
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10
Q

What are the renal causes of secondary hypertension

A

Renal artery stenosis
Polycystic Kidney Disease
Chronic Renal Failure
Glomerulonephritis

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11
Q

What are the endocrine causes of secondary hypertension

A 
Primary hyperaldosteronism
Phaeochromocytoma
Cushing's Syndrome
Acromegaly
Hyper/hypothyroidism
Exogenous hromonses (steroids/OCP)
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12
Q

What are the neurogenic causes of secondary hypertension

A

RICP

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13
Q

What are the other causes of secondary hypertension

A 
White coat HPT
Isolated systolic hypertension (elderly - calcified atherosclerosis)
Sleep apnoea
Pre-eclampsia
Coarctation of the aorta
Hypercalcaemia
Hypercapnoea
Porphyria
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14
Q

Describe how hypertension causes heart disease

A

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.

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15
Q

How can myocardial ischaemia occur in the absence of coronary artery disease in the context of hypertension

A

Hypertrophied myocardium and afterload –> increased demand

High intramural pressure –> compromised blood and O2 supply

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16
Q

Should a patient with uncontrolled stage 1/2 HPT be cancelled?

A

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.

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17
Q

Should a patient with uncontrolled stage 3 HPT be cancelled?

A

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.

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18
Q

Which antihypertensive drugs are often omitted preoperatively

A

ACEi
ARBs
Alpha blockers

19
Q

Describe ECG evidence of LVH

A

There are several simple formulae to diagnose LVH on ECGs. However, sensitivity tends to be quite low.

The Sokolow and Lyon criteria:

S in V1 + R in V5 or V6 (whichever is larger) ≥35 mm
R in aVL ≥11 mm

20
Q

What LVH with strain pattern

A

S in V1 + R in V5 or V6 (whichever is larger) ≥35 mm
R in aVL ≥11 mm

WITH inverted T waves in V4 - V6

21
Q

How is a diagnosis of LVH made on ECHO

A

Normal LV myocardial wall thickness at the END of DIASTOLE is 0.6 to 1.1 cm thick

Myocardium thickness > 1.1 cm –> diagnosis of LVH can be made

22
Q

List the Risks of Anaesthesia to Hypertensive Patients

A
  1. Cardiovascular lability
  2. Perioperative myocardial ischaemia and arrhythmias
  3. Perioperative organ dysfunction
23
Q

What should be considered in the instance of cardiovascular lability

A

Remifentanyl

Invasive arterial BP monitoring

24
Q

In patients with HPT what is the intraoperative BP target

A

Within 20 % of baseline values

25
Q

Why is it important to maintain BP within 20% of baseline

A

Hypertension changes autoregulation of organ blood flow around the higher pressure

26
Q

What additional intra-operative monitoring is appropriate in severe uncontrolled HPT

A

5 lead ECG with ST analysis
IABP
CVP (Stiff LVH may require adequate preload to maintain SV)

27
Q

True or false and why: The presence of left ventricular hypertrophy on ECG necessitates echocardiography

A

Echocardiographic assessment is sought based on the patient’s symptoms and signs and the procedure proposed. An isolated finding of LVH on ECG does not warrant an echo. However, if this is combined with poor exercise tolerance or an ejection systolic murmur, an echo might be required.

28
Q

How is La Place law applied clinically

A

Laplace’s law applies to the increased force of contraction and wall tension required to maintain cardiac output in the failing dilated heart.

29
Q

Classify the causes of heart failure

A 
CARDIAC
Ischaemic (2/3rds of cases)
Non-ischaemic
- Alcohol
- Drug-induced
- Metabolic
- Myocarditis
- Genetic
- Idiopathic
- Peripartum
- Valvular heart disease
- Restrictive disease
- Pericardial
- Congenital heart disease

NON-CARDIAC

  • Hypertension
  • High output states
  • Thyroid disease
30
Q

Define NYHA classification of functional capacity in cardiac patients

A

1 - No symptoms during ordinary activities
2 - Symptoms with strenuous activity
3 - Comfortable only at rest
4 - Symptoms at rest

31
Q

How should ejection fraction be interpreted

A

> 60% - good

30 - 60 % moderate

< 30% poor

32
Q

When is transoesophageal ECHO useful

A
  1. When TTE was suboptimal (obese)
  2. In patients on mechanical ventilation
  3. When visualization of posterior structures is required
33
Q

Other imaging studies

LV function may also be assessed by:

A
  1. CT: Cardiac computed tomography (CT) and magnetic 2. MRI: resonance imaging (MRI)
  2. Angiography: Ventriculography during coronary angiography
  3. SPECT: Gated single photon emission computed tomography (SPECT)
  4. MUGA: Multigated acquisition (MUGA) scans
34
Q

What are the clinical signs that suggest decompensated heart failure

A

S3
Crackles
Raised JVP

35
Q

What are the benefits of Five-lead ECG and ST analysis

A

A 5-lead ECG allows simultaneous monitoring of two different leads. This allows us to monitor both the anterior and inferior aspects of the heart, i.e. the regions which are most susceptible to ischaemia.

ST analysis provides continuous measurement of ST segment depression or elevation, by lead, as positive or negative readings, in millimetres, respectively.

36
Q

What is the target range for CVP

A

8 - 12 mmHg

10 - 15 cmH2O

37
Q

List three methods of cardiac output monitoring

A
  1. Pulmonary artery catheter, using thermodilution method
  2. Transoesphageal Doppler
  3. Pulse pressure methods (PiCCOTM, LiDCOTM and VigileoTM)
38
Q

True or false: Urine output is a good guide to peri-operative fluid therapy

A

Urine output is a poor guide to fluid management during the perioperative period for various reasons, including increased antidiuretic hormone (ADH) secretion.

39
Q

How should fluid management be guided in the perioperative period

A

CVP: 8 - 12 (look at trends and response)
Pulse pressure variation
Oesophageal Doppler

40
Q

Define pulsus paradoxus

A

Pulsus paradoxus is a phenomenon in which the difference in systolic blood pressure (BP) between inspiration and expiration is more than 10 mmHg.

41
Q

What is reverse pulsus paradoxus and when does this occur

A

Reverse pulsus paradoxus — occurs during controlled mechanical ventilation when arterial pressure rises during inspiration and falls during expiration due to changes in intra-thoracic pressure secondary to positive pressure ventilation.

42
Q

What are other names for reverse pulsus paradoxus

A

Paradoxical pulsus, respiratory paradox, systolic pressure variation and pulse pressure variation.

43
Q

What is the formula for Stroke Volume Variation (SVV)

A

SVV = (SVmax - SVmin)/SVmean over a respiratory cycle

44
Q

What is the formula for Pulse Pressure Variation (PPV)

A

PPV = (PPmax - PPmin)/PPmean over a respiratory cycle

Diploma in Anaesthesia (73 decks)

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