UBP 1.6 (Short Form): Cardiovascular - Endarterectomy

Question 1

What are your concerns for this patient?

(A 68-year-old, 72 kg, woman with a history of recurrent unilateral transient ischemic attacks (TIAs) over the past week, presents to the operating room for urgent left carotid endarterectomy (CEA). Her medical history is significant for a myocardial infarction one year ago, poorly controlled chronic hypertension, heart failure, diabetes mellitus, and 40 years of tobacco abuse. Additionally, she continues to experience orthopnea and occasional exertional angina. Her medications include digoxin, furosemide, propranolol, aspirin, NPH insulin, and NTG as needed.)

Answer 1

My primary concerns for this patient include:

1. her current cardiac status with a history of MI and heart failure, exertional angina, and orthopnea;
2. her history of poorly controlled HTN, which is associated with peri-operative hemodynamic instability and increased risk of post-operative complications;
3. the potential for perioperative complications associated with diabetes, such as hyperglycemia, hypoglycemia, hemodynamic instability (possible diabetes-induced diabetic autonomic neuropathy), silent ischemia (possible diabetes-induced diabetic autonomic neuropathy), neurologic injury (there is an increased risk of ischemic neural injury in the setting of hyperglycemia), and aspiration (possible diabetes-induced diabetic autonomic neuropathy); and
4. her history of recurrent TIAs, which are suggestive of embolic stroke and/or inadequate collateral circulation through the circle of Willis.
5. These medical conditions will make it very challenging to maintain adequate cerebral perfusion during cross clamping, while avoiding excessive cardiac stress. Finally, I am concerned that – this patient may experience a perioperative myocardial infarction (the primary cause of perioperative mortality associated with CEA) or stroke (the primary cause of perioperative morbidity associated with CEA).

Question 2

How would you evaluate this patient, preoperatively?

(A 68-year-old, 72 kg, woman with a history of recurrent unilateral transient ischemic attacks (TIAs) over the past week, presents to the operating room for urgent left carotid endarterectomy (CEA). Her medical history is significant for a myocardial infarction one year ago, poorly controlled chronic hypertension, heart failure, diabetes mellitus, and 40 years of tobacco abuse. Additionally, she continues to experience orthopnea and occasional exertional angina. Her medications include digoxin, furosemide, propranolol, aspirin, NPH insulin, and NTG as needed.)

Answer 2

In evaluating this patient preoperatively, I would:

1. perform a careful neurologic exam to identify any current deficits;
2. ensure that she is not suffering from an acute cardiac condition, such as – unstable angina or unstable congestive heart failure
   
   • (which would require delaying surgery);
3. order a –
   
   • hemoglobin level (often abnormal in this patient population),
   • urinalysis (to determine baseline renal function),
   • ECG,
   • chest x-ray (to identify cardiomegaly, pulmonary edema, COPD, or pneumonia), and
   • an ABG (determining the patient’s baseline PaCO2 is important since normalizing the PaCO2 of a patient with chronic hypercarbia could lead to decreased cerebral blood flow);
4. consider ordering an echocardiogram to evaluate her left ventricular function if this had not been done in the last 12 months, or if her clinical status had worsened;
5. evaluate her for signs of autonomic neuropathy
   
   • (since the patient suffers from IDDM);
6. obtain a series of blood pressure and heart rate measurements in order to identify acceptable ranges for perioperative management
   
   • (where there are no changes in mental status or signs of cardiac ischemia);
7. optimize her –
   
   • blood sugar, (to avoid an increased risk of ischemic neurologic injury),
   • blood pressure, and
   • cardiac function (patient has orthopnea, exertional angina, and a history of myocardial infarction);
8. provide reassurance and minimal sedation to relieve any patient anxiety to avoid detrimental increases in heart rate, blood pressure, and myocardial oxygen consumption
   
   • (keep in mind that overaggressive sedation may delay emergence); and
9. continue her cardiac medications.

Question 3

How would you evaluate her cardiac status?

(A 68-year-old, 72 kg, woman with a history of recurrent unilateral transient ischemic attacks (TIAs) over the past week, presents to the operating room for urgent left carotid endarterectomy (CEA). Her medical history is significant for a myocardial infarction one year ago, poorly controlled chronic hypertension, heart failure, diabetes mellitus, and 40 years of tobacco abuse. Additionally, she continues to experience orthopnea and occasional exertional angina. Her medications include digoxin, furosemide, propranolol, aspirin, NPH insulin, and NTG as needed.)

Answer 3

(See notes in UBP Book #1. p. 128)

I would start by conducting a history and physical to:

1. assess the severity and stability of her cardiac disease,
2. detect any acute cardiac conditions, and
3. identify any previous medical interventions.

Since her coronary artery disease, cerebrovascular disease, insulin-dependent diabetes, heart failure, and the type of surgery she is undergoing place her at elevated risk for a major adverse cardiac event (MACE), I would –

1. determine her functional status.
   
   1. If her functional status were greater than 4 METS, I would –
      
      • proceed with surgery without further testing.
   2. If, however, her function capacity were poor (< 4 METs) or unknown (e.g. sedentary lifestyle), I would –
      
      • consult with the surgeon and patient in an attempt to determine if the results of further cardiac testing would alter her care
        
        • (e.g. would the surgeon still proceed with surgery or would the patient agree to undergo prior CABG or percutaneous coronary intervention).
        • If it were decided that positive test results would alter the management plan, I would –
2. consider pharmacologic stress testing (e.g. dobutamine stress echocardiography) to identify any myocardium at risk.

Question 4

What testing would you recommend to assess her risk for cardiac ischemia?

(A 68-year-old, 72 kg, woman with a history of recurrent unilateral transient ischemic attacks (TIAs) over the past week, presents to the operating room for urgent left carotid endarterectomy (CEA). Her medical history is significant for a myocardial infarction one year ago, poorly controlled chronic hypertension, heart failure, diabetes mellitus, and 40 years of tobacco abuse. Additionally, she continues to experience orthopnea and occasional exertional angina. Her medications include digoxin, furosemide, propranolol, aspirin, NPH insulin, and NTG as needed.)

Answer 4

Since she is having frequent TIAs placing her at increased risk of stroke,

I would only delay surgery for more extensive cardiac evaluation if I believed the cardiac risk outweighed the benefits of immediate surgery, and if it were determined that a positive test result would alter the management plan.

In such a case, testing that would measure cardiac function at rest and under stress, such as dobutamine stress echocardiography or an Adenosine Thallium stress test, would provide helpful information that may alter the surgical and/or anesthetic plan.

In the case of severe carotid artery disease and severe coronary artery disease, the surgeon may consider a combined procedure, with CABG and CEA performed under on anesthetic, or staging the procedures one after the other.

Question 5

When would cardiac revascularization be indicated prior to CEA?

(A 68-year-old, 72 kg, woman with a history of recurrent unilateral transient ischemic attacks (TIAs) over the past week, presents to the operating room for urgent left carotid endarterectomy (CEA). Her medical history is significant for a myocardial infarction one year ago, poorly controlled chronic hypertension, heart failure, diabetes mellitus, and 40 years of tobacco abuse. Additionally, she continues to experience orthopnea and occasional exertional angina. Her medications include digoxin, furosemide, propranolol, aspirin, NPH insulin, and NTG as needed.)

Answer 5

While prior CABG or PTCA may improve the cardiac outcome in patients with severe cardiac disease, it may increase the risk of perioperative stroke (since the patient is undergoing the cardiac procedure without first surgically addressing significant carotid disease).

On the other hand, while proceeding with carotid endarterectomy prior to performing CABG or PTCA may reduce the risk of stroke, it may be associated with increased cardiac morbidity.

Since there is insufficient evidence to show improved outcomes with either a combined procedure (performing both CEA and CABG at the same time) or staged procedures (performing one procedure first and the other procedure at a later date),

the decision should be made in conjunction with the vascular surgeon and a cardiologist, taking into consideration the relative severity of the disease processes, the skill of the surgeon, and institution-specific outcomes.

Question 6

What anesthetic technique would you use for this case?

(A 68-year-old, 72 kg, woman with a history of recurrent unilateral transient ischemic attacks (TIAs) over the past week, presents to the operating room for urgent left carotid endarterectomy (CEA). Her medical history is significant for a myocardial infarction one year ago, poorly controlled chronic hypertension, heart failure, diabetes mellitus, and 40 years of tobacco abuse. Additionally, she continues to experience orthopnea and occasional exertional angina. Her medications include digoxin, furosemide, propranolol, aspirin, NPH insulin, and NTG as needed.)

Answer 6

(For this question, when you make your case, Dr. George encourages you to address both sides. Pros/Cons of regional anesthesia)

While there is no evidence that either general or regional anesthesia is superior for CEA,

my preference would be to perform regional anesthesia due to this patient’s significant cardiac disease.

However, recognizing that phrenic nerve paresis is commonly associated with cervical plexus blockade, I would first ensure the absence of severe pulmonary disease prior to deciding to employ regional anesthesia

(the loss of diaphragmatic function on the side of phrenic nerve paresis may not be well tolerated by patients with severe pulmonary disease).

Regional anesthesia would potentially be beneficial for a patient with cardiac disease because it would –

• provide greater hemodynamic stability,
• avoid the myocardial depression associated with general anesthesia,
• avoid the need for tracheal intubation and the associated sympathetic response, and
• reduce the need for vasopressor administration with its associated increase in afterload.

Moreover, it allows for –

• continuous neurologic assessment of an awake patient, which is –
  
  • considered the most sensitive method of detecting cerebral ischemia and
  • aids in more selective carotid artery shunting.

Finally, there may be –

• reduced hospital costs associated with the use of regional anesthesia, and randomized trials have shown
• a reduced incidence of postoperative wound hematoma.

There are, however, disadvantages of regional anesthesia including –

• limited access to an unsecured airway (should conversion to general anesthesia become necessary),
• an inability to deliver pharmacologic agents for cerebral protection without first securing the airway, and
• the need for a high level of patient cooperation.

Moreover, I would avoid regional anesthesia when:

1. there was a strong patient preference for general anesthesia,
2. there is a language barrier that would make communication with the patient unacceptably difficult,
3. the patient’s anatomy was such that more aggressive submandibular retraction would likely be required (i.e. short neck and/or higher than normal carotid bifurcation).

Clinical Notes:

• General Anesthesia
  
  • Benefits:
    
    • Provides for a still patient and operative field
    • More Definitive control of the patient’s airway and ventilation
    • Preserves the option to utilized pharmacologic intervention for brain protection
  • Disadvantages:
    
    • Takes away the ability to perform repeated neurologic exams
    • Potentially leads to greater hemodynamic instability secondary to induction, intubation, and extubation
• Regional Anesthesia:
  
  • Sometimes regional anesthesia is insufficient because the patient’s carotid disease extends so high that the incision must be extended into tissues innervated by cranial nerves.
  • Sympathetic afferent carotid innervation of the carotid sheath results in pain for many patients despite adequate regional anesthesia (the surgeon may need to inject local into the carotid sheath).
  • Adjusting the retractor, local anesthetic supplementation, or a mandibular nerve block may be required when patients experience pain in the jaw, molar teeth, or ear.

Question 7

Would you administer any premedications for this case?

(A 68-year-old, 72 kg, woman with a history of recurrent unilateral transient ischemic attacks (TIAs) over the past week, presents to the operating room for urgent left carotid endarterectomy (CEA). Her medical history is significant for a myocardial infarction one year ago, poorly controlled chronic hypertension, heart failure, diabetes mellitus, and 40 years of tobacco abuse. Additionally, she continues to experience orthopnea and occasional exertional angina. Her medications include digoxin, furosemide, propranolol, aspirin, NPH insulin, and NTG as needed.)

Answer 7

Preoperative anxiety can lead to detrimental effects on the heart, such as increases in heart rate, systemic vascular resistance, and myocardial oxygen consumption.

Fortunately, in most cases, reassurance obviates the need for sedative premedications that can lead to delayed emergence and delayed postoperative neurological examination.

If, however, the patient were anxious, I would consider a small amount of narcotic prior to line placement.

Additionally, I would administer any chronic cardiovascular medications that the patient had not taken at home (the perioperative discontinuation of aspirin is associated with an increased incidence of MI and TIA in patients undergoing carotid endarterectomy).

• (Note – would avoid anxiolytic if possible.*
• – Consider B-blocker in consultation with cardiologist (because of CHF).*

Question 8

Xtra Q – Which monitors would you place?

• (See #4 in long form)*
• (A 68-year-old, 72 kg, woman with a history of recurrent unilateral transient ischemic attacks (TIAs) over the past week, presents to the operating room for urgent left carotid endarterectomy (CEA). Her medical history is significant for a myocardial infarction one year ago, poorly controlled chronic hypertension, heart failure, diabetes mellitus, and 40 years of tobacco abuse. Additionally, she continues to experience orthopnea and occasional exertional angina. Her medications include digoxin, furosemide, propranolol, aspirin, NPH insulin, and NTG as needed.)*

Answer 8

5-lead EKG, ST-segment analysis, neuromonitoring… see Long Form Q#4

Question 9

Xtra Q – What is the significance of a digoxin level of 2.2?

(See UBP 2.8 - CABG)

(A 68-year-old, 72 kg, woman with a history of recurrent unilateral transient ischemic attacks (TIAs) over the past week, presents to the operating room for urgent left carotid endarterectomy (CEA). Her medical history is significant for a myocardial infarction one year ago, poorly controlled chronic hypertension, heart failure, diabetes mellitus, and 40 years of tobacco abuse. Additionally, she continues to experience orthopnea and occasional exertional angina. Her medications include digoxin, furosemide, propranolol, aspirin, NPH insulin, and NTG as needed.)

Answer 9

If you do not necessarily know therapeutic specific level… you can say – I do know that if it is in the toxic level, then…

(This question is asked to practice answering something you do not know specifically – unlikely to be asked this way…)