Anaesthesia - Study Points Flashcards

Question 1

Q

Evaluation of cardiac risk prior to non-cardiac surgery
- What is the incidence of an adverse postoperative cardiovascular outcome related to?
- List 2 Cardiac risk models?
- What is the Cardiac Risk Index? 6 Lee Variables?

Answer

A

The incidence of an adverse cardiovascular outcome is related to the baseline risk.
Risk models estimate the risk based on information obtained from the history, physical examination, electrocardiogram, and type of surgery. When assessing preoperative cardiac risk, we use either the revised cardiac risk index (RCRI), also referred to as the Lee index (table 1), or the American College of Surgeons’ National Surgical Quality Improvement Program risk (ACS-NSQIP) model calculator. The RCRI is simpler and has been widely used and validated over the past 15 years.

Question 2

Q

Patients with underlying cardiovascular disease, including peripheral artery disease or stroke, have an increased risk of perioperative cardiac complications compared to patients without extant atherosclerosis for which two reasons?

Question 3

Q

Outline an algorithm for assessment of the risk of a cardiovascular perioperative cardiac event.
- Steps 1-8?
- 4 Major Clinical Predictors?
- 5 Intermediate Clinical Predictors?
- 6 Minor Clinical Predictors?

Question 4

Q

Evaluation of Cardiac Risk prior to Non-cardiac surgery.
- Which symptoms should physicians enquire about? What history?
- How can cardiac functional status be determined?

Answer

A

At the time of the initial preoperative evaluation, the physician should inquire about symptoms such as:
1. Angina
2. Dyspnoea
3. Syncope
4. Palpitations
5. History of heart disease including ischemic, valvular, or myopathic disease
6. History of hypertension, diabetes, CKD, and cerebrovascular or PAD.

Question 5

Q

Evaluation of cardiac risk prior to non-cardiac surgery
- What features are you looking for on physical examination?
- Which patients should get an ECG as part of their preop work-up?
- What 6 things are you looking for on ECG?

Answer

A

The physical examination should focus on the cardiovascular system, and include blood pressure measurements, auscultation of the heart and lungs, abdominal palpation, and examination of the extremities for oedema and vascular integrity. Important findings include evidence of heart failure or a murmur suspicious for hemodynamically significant valvular heart disease.

Question 6

Q

List 9 clinical and surgery-specific factors associated with an increase in perioperative risk of a cardiovascular event?
- Which 2 other clinical predictors not included in the risk tool are also risk factors for increased risk?

Answer

A

Other clinical predictors — while not included in the risk factors above, the following patient characteristics have been associated with increased risk:
1. Atrial fibrillation – association between a history of prior admission for AF and postoperative complications. The risk associated with AF was higher than that associated with a diagnosis of CAD.
2. Obesity – Obese patients are at increased risk for adverse cardiovascular events at the time of non-cardiac surgery. However, obesity has not been shown to be an independent predictor.

Question 7

Q

Why do we estimate perioperative cardiovascular risk?
- List 4 risk prediction calculators?

Answer

A

Risk prediction calculators
1. Gupta MICA NSQIP database risk model
2. Revised cardiac risk index
3. VSGNE risk index
4. ACS-NSQIP universal surgical risk calculator

Question 8

Q

Evaluation of cardiac risk prior to non-cardiac surgery
- Outline the Gupta MICA NSQIP database risk model.
- Which 5 factors are considered?

Question 9

Q

Evaluation of cardiac risk prior to non-cardiac surgery
- Outline the VSGNE risk index for postoperative cardiovascular complications.

Question 10

Q

Evaluation of cardiac risk prior to non-cardiac surgery
- Outline the ACS-NSQIP universal surgical risk calculator for postoperative cardiovascular complications.

Question 11

Q

Evaluation of cardiac risk prior to non-cardiac surgery
- For patients determined as Higher-risk patients (whose risk of death is 1% or higher), what additional preoperative investigations might you consider? (4)
- What MET level do you not order additional tests?

Question 12

Q

Perioperative myocardial infarction after non-cardiac surgery
- List 4 cardiac complications of non-cardiac surgery and their rate of occurrence?
- Definition of MI?
- How is MI diagnosed in the setting of non-cardiac surgery?

Answer

A

Cardiac complications of death, nonfatal myocardial infarction (MI), heart failure, or ventricular tachycardia occur in up to 5% of patients 45 years of age or older undergoing in-hospital noncardiac surgery.
Of these, perioperative MI is the most common.
Acute myocardial infarction (MI) = a clinical event that results in the death of cardiac myocytes (myocardial necrosis) and is caused by ischemia (but not other etiologies such as myocarditis or trauma)

Question 13

Q

Perioperative myocardial infarction after non-cardiac surgery
- What is Myocardial injury after noncardiac surgery (MINS)?
- Most common cause of MINS?

Question 14

Q

Perioperative myocardial infarction after non-cardiac surgery
- Outline the pathophysiology of perioperative myocardial infarction (MI)?

Question 15

Q

Perioperative myocardial infarction after non-cardiac surgery
- Discuss the incidence of perioperative MI vs. myocardial injury with noncardiac surgery (MINS)?
- Which 3 studies outline this?

Answer

A

## The incidence of MINS is higher than that for MI.

Question 16

Q

How can we predict risk for cardiovascular events (including MI) after noncardiac surgery?
- Which risk index?
- List 6 risk factors?
- In the CARP trial what was specifically associated with the development of post-op MI?
- Which types of surgeries are more high risk?
- In the POISE trial what were 2 additional factors associated with the development of post-op MI?

Answer

A

Risk factors for cardiovascular events (including MI) after noncardiac surgery have been identified and incorporated into validated risk models.
The revised Goldman cardiac risk index is the best validated risk index and appears to have greater predictive value than other risk indices.
Risk factors:
1. High-risk surgery
2. Hx of ischemic HD
3. Heart failure
4. CVD
5. Diabetes mellitus requiring treatment with insulin
6. Preoperative serum creatinine >2.0 mg/dL.

Question 17

Q

Perioperative MI after non-cardiac surgery
- What risk does perioperative hemorrhage pose as a predictor of MI (or stroke)?
- List 5 preoperative independent predictors of perioperative MI found in the POISE-2 trial?

Question 18

Q

Perioperative MI after non-cardiac surgery
- How might patients with perioperative MI present?
- What % of patients in the POISE trial with MI did not experience ischemic symptoms?
- What is the recommendation?

Answer

A

Patients with perioperative MI may have symptoms and (rarely) signs similar to the broad group of patients with an acute coronary syndrome.
However, due to the influence of anesthetic/ analgesic /amnestic agents, symptoms are often muted, atypical, or absent.
In the POISE trial, approx. 65% of the patients with MI did not experience ischemic symptoms.
We recommend that all patients with symptoms or signs suggestive of myocardial ischemia or those suspected for other reasons such as hemodynamic instability or respiratory distress receive a 12-lead ECH and serial (two or three) troponin measurements.

Question 19

Q

Perioperative MI after non-cardiac surgery
- In the setting of noncardiac surgery, how is the diagnosis of MI made?
- How would you define acute MI in patients for whom troponin was not measured or measured at a time that could have missed the clinical event?
- What are the most common ECG findings for post-op MI?

Answer

A

In patients in whom troponin was not measured or measured at a time that could have missed the clinical event, we believe that new pathologic Q waves on the ECG can define acute MI. For patients in whom the diagnosis remains uncertain after considering symptoms, ECG changes, and the results of biomarker testing, information from additional noninvasive studies (such as a new wall-motion abnormality or fixed defect on echocardiography or radionuclide myocardial perfusion imaging) may be needed.

Question 20

Q

Perioperative MI after non-cardiac surgery
- List 3 Potential causes of an elevated troponin in the absence of criteria for an MI?

Answer

A

DIFFERENTIAL DIAGNOSIS — Potential causes of an elevated troponin in the absence of criteria for an MI include:
1. Pulmonary embolus
2. Sepsis
3. Chronic kidney disease

Question 21

Q

Perioperative MI after non-cardiac surgery
- What is meant by screening for MI perioperatively?
- Who should we use troponin to screen for perioperative MI in?
- Can you diagnose perioperative MI or MINs on elevated troponin alone?
- What is the rationale for for obtaining a baseline cardiac troponin (cTn) all patients at high cardiac risk but without symptoms or ECG changes?
- Should we screen lower risk patients with troponin for perioperative MI?

Answer

A

SCREENING — In this section, screening refers to the use of cardiac biomarker and electrocardiographic (ECG) testing in the perioperative period in patients who have no symptoms (or signs) of myocardial ischemia but who are at relatively high
risk. Troponin is the preferred biomarker.

Question 22

Q

Perioperative MI after non-cardiac surgery
- What is the role of BNP for screening for perioperative MI?

Question 23

Q

Perioperative MI after non-cardiac surgery
- What is the role of ECG for screening for perioperative MI?
- When should you obtain one in an asymptomatic patient?

Answer

A

ECG for Perioperative MI Screening — We suggest at least one 12-lead ECG in all patients with symptoms of myocardial ischemia. However, similar to troponin measurement, the issue of when to obtain a screening ECG(s) in asymptomatic patients is not well studied. Although the evidence to support the routine performance of a postoperative ECG(s) in high-risk patients is weak compared to that for the use of troponin, some of our experts believe such practice is reasonable. “High risk” is defined as in-hospital surgery with one or more additional risk factors of the revised cardiac risk score or any patients with complications of a possible cardiovascular aetiology.

Question 24

Q

Perioperative MI after non-cardiac surgery
- What is the prognosis after perioperative MI?
- What is the in-hospital mortality in patients who have sustained a perioperative MI?
- In the POISE trial, what is the 30 day mortality rate for perioperative MI vs. those without MI?
- What are elevations of cTn, with or without fulfilling criteria for the universal definition of MI are indicative of?
- What is the relationship between postoperative BNP and cardiovascular outcomes?

Answer

A

PROGNOSIS AFTER MI — MI and myocardial injury after noncardiac surgery (MINS) are
associated with worse short- and long-term outcomes, including mortality. Mortality rates are directly related to the sensitivity of the tests that led to the documentation of MI. Low sensitivity tests, particularly biomarkers, will
likely identify larger MIs; these will likely be associated with higher death rates than smaller MIs.

Question 25

Q

Perioperative MI after non-cardiac surgery
- What is management of perioperative MI in non-cardiac surgery based on?
- What 2 medications should all patients who sustain an MI in the perioperative period obtain as a minimum? Doses?
- As well as the above medications, what else is advised for the firs 24 hours?

Question 26

Q

Perioperative MI after non-cardiac surgery
What are the management recommendations based on the type of perioperative event:
1. ST-elevation MI (STEMI)?
2. non-ST elevation MI (NSTEMI)
3. Troponin elevation without other criteria for MI?

Answer

A

ST-elevation MI
- Patients with perioperative STEMI are at high risk for death without usual STEMI care, including reperfusion therapy, and are at high risk for a bleeding complication with it.
- In most patients, fibrinolytic therapy is not an option given the recent surgical procedure.
- We usually proceed with urgent primary percutaneous coronary intervention after careful discussion of the benefits and risks with all managing healthcare providers. The patient and family are involved in this process.
- We recommend aspirin and statin for these STEMI patients.
- A P2Y12 receptor blocker is added as soon as a decision is made to implant an intracoronary stent. For patients who receive no reperfusion therapy, we also recommend one year of aspirin plus a P2Y12 receptor blocker (dual antiplatelet therapy).
- We also recommend starting a beta blocker in these patients. However, the potential for hypotension should be considered in the choice of timing and dose.

Question 27

Q

How is Myocardial infarction (MI) in patients undergoing noncardiac surgery defined? How does this compare to Myocardial injury after noncardiac surgery (MINS)?

Answer

A

Myocardial infarction (MI) in patients undergoing noncardiac surgery is defined as a rise in biomarker (either troponin or creatine kinase MB fraction) in association with suggestive symptoms or electrocardiographic changes. Myocardial injury after noncardiac surgery (MINS) requires only an elevated biomarker postoperatively when there is no evidence of
a non-ischemic cause.

Question 28

Q

What are the recommendations with regard to:
1. Measurement of cardiac biomarkers in high-risk patients for perioperative MI?
2. Obtaining a 12-lead ECG?

Question 29

Q

What is the recommended treatment for all patients with perioperative MI or MINS?
Doses?
Which additional medication should be given to STEMI patients?

Answer

A

For all patients with perioperative MI or MINS, we recommend treatment with statin and aspirin therapy (Grade 1B).
On day one of therapy, we typically give atorvastatin 80 mg and aspirin 81 to 325 mg; we continue with the same dose of atorvastatin and aspirin 75 to 100 mg daily.
For patients with ST-elevation MI, we recommend treatment with a beta blocker (Grade 1B).

Question 30

Q

What is the most common cause of left ventricular outflow obstruction in both adults and children? Less common causes?

Answer

A

Aortic valve stenosis is the most common cause of left ventricular outflow obstruction in children and adults; less common causes are subvalvular or supravalvular disease.

Question 31

Q

Clinical manifestations and diagnosis of aortic stenosis in adults
- What are the 3 classic clinical manifestations of aortic stenosis (AS)?
- What are the 3 most common presenting symptoms?
- How do the symptoms change over the clinical course?
- What degree of outflow obstruction cause symptoms?
- 3 indicators of severe AS?

Answer

A

The classic clinical manifestations of aortic stenosis (AS) are:
1. Heart failure (HF)
2. Syncope
3. Angina

However, these “classic” manifestations reflect end-stage disease. Now, with earlier diagnosis by echocardiography and prospective follow-up of patients, the following are the most common presenting symptoms:
1. Dyspnoea on exertion or decreased exercise tolerance
2. Exertional dizziness (presyncope) or syncope
3. Exertional angina

These three “early symptoms” are nonspecific. Care must be taken in attributing these symptoms to AS since most patients with these symptoms do not have AS.

Question 32

Q

What is the most common symptom of Aortic Stenosis? What are the 2 factors that contribute to this?
What are the features of low cardiac output states like AS & HF?
- Is atrial fibrillation common in isolated aortic stenosis?

Answer

A

The most common symptom of AS is dyspnoea, usually with exertion. Two factors can contribute: diastolic dysfunction with an increase in left ventricular filling pressures with exercise, and an inability of the left ventricle to increase the cardiac output during exercise.
Systolic left ventricular dysfunction is rare, and overt HF is a late, often end-stage finding, usually in patients who have not received regular medical care. Once overt HF occurs, the patient may complain of shortness of breath, easy fatigability, debilitation, and other signs and symptoms of a low cardiac output state. Patients with severe low-gradient AS with either reduced left ventricular ejection fraction (LVEF) or normal LVEF may present with HF, angina, and/or syncope.
Atrial fibrillation (AF), which is uncommon in isolated AS, often accompanies HF.

Question 33

Q

List 4 of the proposed explanations for exertional dizziness (presyncope) or syncope in patients with AS?

Answer

A

There are several proposed explanations for exertional dizziness (presyncope) or syncope in patients with AS, both of which reflect decreased cerebral perfusion.
1. Exercise-induced vasodilation in the presence of an obstruction with fixed cardiac output can result in hypotension
2. A transient bradyarrhythmia that can occur during or immediately after exertion
3. Abnormalities in the baroreceptor response with an ensuing failure to appropriately increase the blood pressure
4. An arrhythmia, such as atrial fibrillation; ventricular arrhythmias are uncommon

Question 34

Q

Clinical Manifestations of Aortic Stenosis in Adults - Angina Pectoris
What are 4 ways patients with AS and significant obstructive coronary artery disease can develop coronary ischemia?

Answer

A

Angina pectoris
Angina with effort is common in patients with severe AS. Approximately one-half of these patients have underlying coronary artery disease. CAD is also seen in a minority of patients with severe AS without
angina.

Question 35

Q

What are the clinical features on physical examination of Aortic Stenosis?
- 3 findings which are most useful for ruling in AS?
- What is the most useful finding for ruling out AS?
- How sensitive/specific are the physical findings for severe valvular obstruction?

Answer

A

The physical examination often provides the first clue to the presence of AS. The physical
examination correlates with the severity of AS, though no combination of physical findings has both a high sensitivity and high specificity for excluding severe AS, particularly in asymptomatic patients.

Question 36

Q

Describe the Carotid pulse in a patient with Aortic Stenosis?

Answer

A

Carotid pulse in AS — the quality of the arterial pulse in AS reflects the obstruction to blood flow into the peripheral arterial circulation. The arterial pulse has been described as “parvus and tardus,” (i.e., it is small or weak and rises slowly). This is best appreciated in the carotid artery where the pulse is reduced in amplitude and delayed in occurrence. However, the amplitude of the carotid upstroke may be preserved in older patients with AS due to vascular changes. The delay can be appreciated by simultaneous palpation of the apex (point of maximum impulse) and the carotid artery. There may also be an associated carotid artery thrill or coarse vibration (“shuddering”) due to the marked turbulence of blood flow across the stenotic valve.

Question 37

Q

What would you expect to find on precordial palpation of a patient with Aortic Stenosis? (3 points)

Answer

A

Precordial palpation
- The cardiac impulse at the apex is sustained and is initially normal in location.
- Some patients have a palpable fourth heart sound (S4) due to vigorous left atrial contraction into the noncompliant ventricle.
- In addition, a systolic thrill may be felt at the base of the heart (second intercostal space) or at the sternal notch, especially during full expiration with the patient leaning forward.

Question 38

Q

What would you expect to find on cardiac auscultation of a patient with Aortic Stenosis?
- How is the murmur associated with AS described?
- Where is it heard best?
- How specific is a loud murmur (grade 4 or greater) for severe AS?
- How does the timing of the murmur correlate to severity?
- What is the Gallavardin phenomenon?

Question 39

Q

What might you find on a CXR of a patient with Aortic Stenosis?

Answer

A

A CXR is not generally required when evaluating AS but may be obtained in some patients who present with heart failure and also in some patients who present with dyspnoea to exclude other causes for shortness of breath.
The routine CXR is usually normal when AS is mild to moderate. In adults with severe calcific AS, calcification of the aortic leaflets and aortic root may be visible on an overpenetrated CXR or on fluoroscopy, but it is rarely detected on routine CXR.
A rounding of the left ventricular apex suggestive of left ventricular hypertrophy may be identified in some patients with severe AS.
Another finding that may be identified on the CXR is dilatation of the ascending aorta, which is due to the tissue abnormalities associated with a bicuspid aortic valve or to coexisting atherosclerosis or hypertension in patients with calcific disease.

Question 40

Q

Diagnosis of Aortic Stenosis in Adults
- When should you suspect AS?
- Outline an approach to diagnosis and evaluation?
- What is the primary test in the diagnosis and evaluation of AS?

Answer

A

AS is usually diagnosed when physical examination (including a typical systolic ejection murmur) suggests AS or when AS is detected on an echocardiogram performed for other indications.
Symptoms such as dyspnoea and decreased exercise tolerance, dizziness, syncope, and angina pectoris may or may not be present in patients with severe AS.

Question 41

Q

Diagnosis of Aortic Stenosis - Echocardiogram
- What is being evaluated?
- How might the appearance of aortic leaflets on echo differ in adults with AS vs. congenital?
- What are the 2 standard parameters used for evaluation of stenosis severity and what is used to assess them?
- How does the left ventricular chamber usually appear? What about the left ventricular wall?
- What provides the most reliable non-invasive estimation of the pulmonary artery pressure?
- What % of AS patients have a severe elevation in pulmonary artery pressure?
- What do 80% of patients with AS have concurrently?

Question 42

Q

Diagnosis of Aortic Stenosis - ECG
- What is the main value for ECG in the diagnosis of AS?
- What are the primary ECG findings?
- Does the absence of hypertrophy on the ECG does exclude the presence of severe AS?

Question 43

Q

Diagnosis of Aortic Stenosis - Stress testing
When is Exercise stress testing suggested for patients with AS? Who should NOT receive it?

Answer

A

Exercise testing is suggested in selected patients with asymptomatic severe AS (maximum aortic valve velocity of ≥4.0 m/s or mean aortic valve pressure gradient ≥40 mm) to confirm asymptomatic status. Such evaluation is particularly helpful when a patient’s functional capacity is unclear or low. Patients with severe AS who develop typical symptoms of AS (e.g., exertional dyspnoea) during low level exercise testing should be considered symptomatic even if the
clinical history is uncertain. Exercise testing should not be performed in patients with symptomatic severe AS.

Question 44

Q

Diagnosis of Aortic Stenosis - BNP
- Is it recommended to perform routine measurement of plasma BNP or N-terminal pro-BNP (NT-proBNP) in patients with AS?
- Among patients with severe AS, what are higher values independently predictive of?
- What is a potential limitation to BNP measurement in patients with AS?

Question 45

Q

What is the role of Cardiovascular magnetic resonance in the diagnosis and evaluation of Aortic Stenosis?

Question 46

Q

What is the role of CT in the diagnosis and evaluation of Aortic Stenosis?

Answer

A

CT can provide quantitative evaluation of the amount of valve calcification, but experience with CT quantification of aortic valve area is limited. The degree of aortic valve calcification
correlates with both echocardiographic determination of stenosis severity and clinical outcomes. However, the role of quantitation of valve calcium in clinical decision-making has not been defined.

Question 47

Q

What is the role of Cardiac catheterization in the diagnosis and evaluation of Aortic Stenosis?
- When is it indicated?
- What is the major risk associated with this?

Question 48

Q

What are the differential diagnoses of Aortic Stenosis?
- Subvalvular disease?
- Supravalvular disease?

Question 49

Q

How is Aortic Stenosis Staged? Based on 4 things?

Answer

A

Aortic stenosis (AS) is staged according to:
1. Valve anatomy
2. Valve hemodynamics,
3. Haemodynamic consequences of AS
4. Symptoms

Question 50

Q

What is Stage A of Aortic Stenosis? What are the Valve Haemodynamics?

Answer

A

In stage A, patients with bicuspid aortic valve (or other congenital aortic valve anomaly) or aortic sclerosis are at risk for aortic stenosis and have no symptoms. The maximum transvalvular aortic velocity (Vmax) is <2 m/s.

Question 51

Q

What is Stage B of Aortic Stenosis?
- How is Mild AS defined?
- How is Moderate AS defined?

Answer

A

In stage B, patients have progressive AS with mildly to moderately calcified valve leaflets, mildly to moderately
reduced valve leaflet mobility, and mild or moderate AS with no symptoms.
- Mild AS is identified by an aortic Vmax 2.0-2.9 m/s or mean transvalvular pressure gradient <20 mmHg.
- Moderate AS is identified by an aortic Vmax 3.0-3.9 m/s or mean transvalvular pressure gradient of 20-39 mmHg.

Question 52

Q

What is Stage C of Aortic Stenosis?
- C1 vs. C2?

Answer

A

Patients in stages C and D have a severely reduced valve opening (with severe leaflet calcification or congenital stenosis) and severe AS.
In stage C, patients have asymptomatic severe AS. Aortic Vmax is ≥4 m/s or mean transvalvular pressure gradient is ≥40 mmHg. Aortic valve area is typically ≤1.0 cm2 (or aortic valve area indexed to body surface area is ≤ 0.6 cm2/m2).
In stage C1, LVEF is normal.
In stage C2, left ventricular ejection fraction is <50%.

Question 53

Q

What is Stage D of Aortic Stenosis?
- D1?
- D2?
- D3?

Question 54

Q

What needs to be considered when assessing valve area in patients with Aortic Stenosis?

Answer

A

Body size should be considered in assessing valve area. The above staging system includes aortic valve area indexed to body
surface area. However, caution should be used in the application of body surface area indexing since this can lead to misleading conclusions, particularly in obese patients. The optimal anthropometric index remains to be defined.

Question 55

Q

List 6 Complications of Aortic Stenosis.

Answer

A

List 7 Complications of Aortic Stenosis
1. Sudden cardiac death
2. Arrhythmias
3. Endocarditis
4. Bleeding tendency
5. Embolic events
6. Concurrent coronary disease

Question 56

Q

How can Aortic Stenosis result in Sudden Cardiac Death?
- What are the potential mechanisms for this?
- What is the Bezold-Jarisch reflex?
- What reduces the risk of sudden cardiac death in AS patients?

Answer

A

Symptomatic severe AS is associated with a high risk of sudden cardiac death.
- In patients with severe AS but no reported symptoms, the annual incidence of sudden death is approx. 1%.
- In adults with symptoms due to severe AS, the annual incidence of sudden death is 8-34%.
- The mechanism of sudden death has not been established.
- Potential causes include an abnormal Bezold-Jarisch reflex with hypotension, bradyarrhythmias, or malignant ventricular tachyarrhythmias.
- However, a relationship between ventricular arrhythmias and sudden death has not been established.
- The risk of sudden death is reduced by valve replacement so prompt valve replacement is generally recommended for symptomatic AS.

Question 57

Q

How many patients with Aortic Stenosis with develop Atrial Fibrillation?

Question 58

Q

What percetnage of patients with Aortic Stenosis develop Infective Endocarditis?
- What are the recommendations regarding prophylactive antibiotics prior to dental procedures or invasive procedures that produce significant bacteraemia with organisms associated with endocarditis?

Question 59

Q

Why do patients with Aortic Stenosis have an increased risk of bleeding?
- What is the syndrome called?

Question 60

Q

Are embolic events a common complication of Aortic Stenosis?

Answer

A

Isolated case reports have described cerebral or systemic embolic events due to calcium emboli in patients with AS. This appears to be an infrequent complication. In a cohort study that included 515 patients with calcific AS, 300 with aortic valve calcification without stenosis, and 562 controls, the stroke rates were not different at two years (5, 8, and 5%, respectively).

Question 61

Q

What percentage of patients with Aortic Stenosis have concurrent coronary disease?

Answer

A

Severe isolated AS is primarily a disease of older patients. In a report cited above of 932 adults who underwent surgery for isolated AS, almost all were over age 50 and more than one-half were over age 70. Thus, adults with moderate to severe AS have a high prevalence of coexisting CAD and are at risk for clinical events due to coronary disease. The magnitude of risk was illustrated in a prospective study of 123 adults with asymptomatic AS who were followed for an average of 2.5 years. MI occurred in 3%, PCI in 2%, and CABG without valve replacement in 2%.

Question 62

Q

Aortic Stenosis - Summary
- What are the classic symptoms? What are the most common symptoms?
- What is the evolution of symptoms? How does the degree of outflow obstruction correlate to symptoms?
- Which findings on physical examination are sensitive/ specific for severe AS?
- Diagnosis?
- Differentials?
- Staging?

Question 63

Q

What is the Incidence of Aortic Stenosis?

Answer

A

Risk models have identified severe AS as a major clinical predictor of adverse outcomes. Population studies from the United States and Europe have reported AS in approximately 1-2% of
individuals 65-75 years with prevalence increasing to 3 -8% in individuals ≥75 years old. In the Helsinki Aging study, nearly 3% of the individuals between 75-86 years of age had critical AS. Patients with AS frequently have concurrent cardiovascular disease with approximately half of patients with AS aged >50 years having concomitant coronary heart disease. Aortic stenosis remains the most important valve pathology as far
as perioperative significance, in our population, is concerned. Mitral stenosis has the same implications as far as it is also a fixed cardiac output state, but is fortunately rare.

Question 64

Q

Describe the Pathophysiology of Aortic Stenosis?

Answer 40

A

Evaluation of symptoms and signs of cardiac disease
Preoperative echocardiographic assessment of AS severity and ventricular (LV) function
Careful evaluation for coexisting coronary artery disease (CAD) and other cardiac risk factors.
Estimation of the risk of non-cardiac surgery

Answer 41

A

Studies evaluating the precision and accuracy of the clinical examination found that four findings were useful for diagnosis of AS:
1. A slow rate of rise and reduced peak in the carotid pulse
2. Mid to late peak intensity of the murmur
3. Maximal murmur intensity at the second right intercostal space
4. Reduced intensity of the second heart sound or single S2

Answer 42

A

Increased risk of bleeding — Patients with moderate to severe AS have a bleeding tendency due to an acquired von Willebrand syndrome, which may increase the risk associated with non-cardiac surgery.

Answer 43

A

For patients with AS who have indications for aortic valve replacement (such as symptomatic severe AS),
we recommend postponing elective non-cardiac surgery since severe AS is a risk factor for perioperative morbidity and
mortality. The indications for aortic valve replacement are the same as in the absence of planned non-cardiac surgery.

Answer 44

A

Management recommendations are based in part upon observation of the following pathophysiologic changes with AS:
1. The chronic pressure overload state results in concentric hypertrophy, thereby reducing the compliance of the left ventricle.
2. The concentric hypertrophy also reduces coronary reserve as discussed above, rendering the patient more susceptible to ischemia in situations of increased myocardial oxygen demand with and without the presence of concomitant coronary artery disease.

Answer 45

A

Patients with significant aortic stenosis (AS) are at increased risk for cardiac complications, including:
1. Intraoperative hypotension
2. Myocardial infarction
3. Ischemia
4. Heart failure
5. Arrhythmias
6. Death

Answer 46

A

**Evaluation and management of cardiac risk **
General considerations — all patients with ischaemic heart disease scheduled to undergo non-cardiac surgery should be assessed for the risk of a perioperative cardiovascular event. Risk is related to both the type of surgical procedure and individual patient factors.

Answer 47

A

Laboratory — Criteria for ordering preoperative blood tests are the same for patients with ischemic heart disease as for other patients undergoing non-cardiac surgery. It is reasonable to obtain a metabolic panel (sodium, potassium, chloride,
bicarb, urea, creatinine) in patients receiving diuretic therapy chronically and in patients with renal insufficiency.
Electrocardiogram — In general, we agree with the 2014 American College of Cardiology/American Heart Association guidelines and the 2014 European Society of Cardiology/European Society of Anesthesiologists guidelines for preoperative cardiovascular evaluation and management. A preoperative baseline resting 12-lead ECG is obtained in patients with known IHD, except for those undergoing low-risk surgery. However, if the patient’s symptoms are unchanged and there is an ECG less than 6 months old in their file, this is usually sufficient.

Answer 48

A

Anaesthetic goals in patients with IHD are:
1. Prevention
2. Detection,
3. and Treatment of myocardial ischaemia.

Prevention of ischaemia — The following haemodynamic and physiologic goals optimise myocardial oxygen (O2) supply and minimise myocardial O2 demand, regardless of the surgical procedure or the anaesthetic techniques and agents selected.

Answer 49

A

Premedication — Regardless of the anaesthetic technique that is selected, pain or anxiety causing tachycardia and hypertension in the preoperative period is treated. If the patient is in a monitored setting, midazolam 1-4 mg is often used shortly before (within 30-60 minutes) or during induction of general anaesthesia as an adjunct to alleviate anxiety. However, since midazolam may cause mild decreases in systemic BP and cardiac output, the dose is reduced or eliminated in hypovolaemic patients and in the elderly. Similarly, small doses of an opioid (e.g., fentanyl 25-50 mcg) may be administered to treat preoperative pain in a monitored setting, with care to avoid respiratory depression

Answer 50

A

Selection of anaesthetic technique — the choice of anaesthetic technique should be guided primarily by the requirements for the procedure and by surgeon and patient preferences.

Answer 51

A

Local anaesthesia with monitored anaesthesia care
For patients with ischemic heart disease receiving monitored anaesthesia care (MAC), key issues are avoidance of tachycardia and hypertension caused by pain and/or anxiety, because
these hemodynamic changes increase myocardial oxygen demand and/or decrease myocardial oxygen supply. Thus, small doses of short-acting agents (e.g., midazolam, opioids, propofol, or dexmedetomidine) are administered to provide analgesia, anxiolysis, and/or sedation. In patients with ischemic heart disease,
it is particularly important to employ continuous monitoring to detect changes such as development of hypotension or
respiratory depression with resultant hypoxemia.

Answer 52

A

Maintenance — in most patients, we prefer a volatile inhalational anaesthetic (e.g., sevoflurane, isoflurane, or desflurane) as the primary agent to maintain GA if either an inhalational or total IV anaesthesia (TIVA) technique may be used. However, in many patients, we may choose TIVA based on surgery-specific or patient-specific
factors.

Answer 53

A

Emergence — during emergence, sympathetic stimulation caused by excitement and pain, as well as stimulation of airway
reflexes during tracheal extubation, increase the potential for tachycardia and hypertension. This may lead to myocardial ischemia. These hemodynamic changes are controlled by optimizing analgesia prior to emergence (e.g., by administering a systemic opioid or doses of LA via an existing epidural catheter) and/or by administering bolus doses of IV beta blockers (e.g., esmolol, labetalol, or metoprolol) and/or vasodilating agents (e.g., labetalol, nicardipine, or nitroglycerin) during and immediately after emergence and extubation.

Answer 54

A

Control of glucose — we maintain perioperative glucose <180 mg/dL (<10 mmol/L) in patients with IHD
and take care to avoid hypoglycemic episodes. Although hyperglycaemia is associated with an approximately 2-4 fold increased risk of a myocardial ischaemic event in vascular and other non-cardiac surgery, hypoglycaemia is also
detrimental. A trial in critically ill patients showed that attempts to tightly control serum glucose (81 to 108 mg/dL [4.5 to 6.0 mmol/L]) are associated with more hypoglycaemic episodes and higher mortality compared with more liberal glucose management (<180 mg/dL [<10 mmol/L]).

Answer 55

A

POSTOPERATIVE MANAGEMENT
Monitoring for ischaemia — the majority of cardiac events in non-cardiac surgical patients occur in the postoperative
period. After high-risk surgery, reasonable precautions include continuous ECG monitoring for myocardial ischaemia or infarction in an ICU or stepdown unit, as well as serial 12-lead ECG
tracings and troponin measurements.

Answer 56

A

Administration of aspirin in the preoperative period depends upon specific patient and surgical factors, but the trend is towards continuing aspirin unless there is a very good reason to cease it.

Answer 57

A

The choice of a regional or general anaesthetic technique is guided primarily by the surgical procedure and patient
choice. For procedures requiring large thoracic or abdominal incisions, we suggest a neuraxial technique for postoperative analgesia.
During onset of a neuraxial block, crystalloid is administered in 250-mL increments to prevent hypotension. Significant
hypotension is immediately corrected by administration of boluses of a vasopressor agent.

Answer 58

A

REVASCULARIZATION BEFORE SURGERY — With the exception of patients with an ACS we do not recommend myocardial revascularization prior to noncardiac surgery to improve perioperative outcomes of non-cardiac surgery. However, some patients, such as those with significant left main CAD, will need revascularization with CABG surgery or PCI to improve long-term survival or, on occasion, to improve the quality of their life. The timing of revascularization relative to the planned noncardiac surgery should be determined by the relative benefits and risks consequent to choosing one procedure to be performed before the other. The decision on timing should be discussed with the patient.

Answer 59

A

The optimal preoperative heart rate and blood pressure for any patient receiving long-term beta blocker therapy is
not known. We suggest that the resting heart rate be between 60-70bpm. Some of our experts hold the dose
on the morning of surgery if the systolic blood pressure is <115 mmHg and half the dose if it is between 116-130 mmHg. Resting tachycardia may indicate inadequate beta blocker effect and should be avoided. Patients with HR >60-70bpm are at
increased risk of death or MI.

Answer 60

A

Antiplatelet therapy — Many patients who undergo noncardiac surgery are treated with long-term antiplatelet therapy (most often aspirin) for the primary or secondary prevention of cardiovascular disease events. For most of these patients taking aspirin monotherapy, we recommend that they hold such therapy 5-7 days before surgery and that aspirin not be started before noncardiac surgery in those not taking aspirin. Patients with an indication for long-term aspirin usage who have their aspirin held prior to surgery should have their aspirin re-started when the perioperative risk of major bleeding has passed. Patients undergoing carotid endarterectomy should have their aspirin continued.

Answer 61

A

Statins
- Among patients undergoing elective surgery, we recommend continuing statin therapy in patients already being treated, and in previously untreated patients at high cardiovascular risk, initiating statin therapy as soon as possible before surgery.
- For patients on statin therapy who are undergoing urgent or emergent major vascular surgery, we recommend continuing such therapy.
- For patients not on statin therapy who are undergoing urgent or emergent major vascular surgery, we suggest initiating therapy before surgery, if possible.

Answer 62

A

PREOPERATIVE EVALUATION — The goals of a comprehensive evaluation for HF prior to noncardiac
surgery include:
1. Recognizing patients who are asymptomatic and lacking a history of HF prior to surgery but who are at risk for developing HF in the postoperative period.
2. Determining whether patients with HF are stable and compensated or show signs and symptoms of decompensation.
3. Recognizing high-risk HF syndromes, including new onset HF.
4. Identifying comorbidities that may impact the stability of HF in the postoperative period.

Answer 63

A

Asymptomatic left ventricular diastolic dysfunction
Asymptomatic left ventricular systolic dysfunction
Compensated HF with preserved ejection fraction (HFpEF; EF ≥45 to 50 percent)
Compensated HF with reduced ejection fraction (HFrEF; EF ≤40 percent)
Decompensated HFpEF
Decompensated HFrEF
Advanced HF/end stage HFrEF

Answer 64

A

Newly diagnosed heart failure — Patients with newly diagnosed HF, especially HFrEF (EF <40%), are at much
higher risk than patients with preexisting HF. In patients with HFrEF, the impact of medical therapy on left ventricular
function and remodeling is generally only realized after three months of treatment.

Advanced heart failure — Clinical features such as:
1. Persistent tachycardia
2. Hypotension
3. Hyponatremia
4. Intolerance to an ACE inhibitor
5. Worsening renal failure
6. History of multiple implantable cardioverter-defibrillator shocks
7. Progressive weight loss,
8. Multiple recent hospitalizations - are strong predictors of poor short-term survival in patients with established HFrEF. These clinical features should influence the decision on the appropriateness and timing of noncardiac surgery.

Answer 65

A

Proceed with surgery without any additional testing or new medical interventions prior to surgery.
Postpone surgery and proceed with surgery only after HF has been stabilized.
Reconsider the need for surgery or explore alternative procedures and therapies.

Answer 66

A

Urgent or elective surgery — For patients with an indication for urgent or elective surgery, more time is available for preoperative risk assessment and management. These decisions can be categorized in terms of the
temporal necessity of surgery (urgent or elective), clinical HF syndrome, and the estimated risk associated with the
intervention.

Answer 67

A

Fluid management — Maintenance of appropriate volume can be challenging in patients undergoing surgery. Fluid shifts and anesthesia may cause temporary hypotension that may lead to excessive fluid administration, resulting in worsening
HF. Care should be taken to limit volume expansion when hypotension is not the result of decreased filling pressures, realizing that third spacing might lead to a requirement for fluid. Intraoperative fluid administration is often
required to maintain insensible losses at a rate of 2 mL per kilogram per hour and 3 mL of crystalloid for each mL of blood loss.

Answer 68

A

Mechanical circulatory support devices
Noncardiac surgery is becoming more common in patients with advanced HF supported by mechanical circulatory support devices such as left ventricular assist devices (LVADs). In specialized units, patients with LVADs can safely undergo noncardiac surgery. It is recommended that patients with LVADs who are scheduled for noncardiac surgery be managed perioperatively by a centre experienced with implantation and follow-up.

Answer 69

A

Institution of long-term therapy
Evidence-based, long-term therapy for HF is initiated or reinstated postoperatively as soon as the patient is hemodynamically stable. The approach to initiation of medications is like that followed for patients hospitalized with acute HF. Patients who develop HF postoperatively have a significantly increased risk of hospital readmission, confirming the need for careful discharge planning and close follow-up, ideally using a multidisciplinary approach.

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Anaesthesia - Study Points Flashcards

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