Clinical Case

Question 1

1. What are the determinants of myocardial oxygen supply?

Answer 1

○ Coronary perfusion is preserved by maintaining both coronary perfusion pressure and length of the diastolic interval.
○ The left coronary artery is perfused during diastole.
○ The right coronary artery is perfused during both diastole and systole.
○ It is important to prevent shortening of the diastolic interval by preventing increases in heart rate.
○ Coronary perfusion pressure is maintained by ensuring normal to high diastolic arterial pressure and normal to low left ventricular end-diastolic pressure (LVEDP).

Question 2

2. Explain the determinants of myocardial oxygen consumption (demand).

Answer 2

1. HR
   • most important parameter
   •Decreasing heart rate increases oxygen supply by prolonging diastole (allowing for more subendocardial perfusion) and decreases oxygen demand
   • Severe bradycardia should be avoided because it causes decreased diastolic arterial pressure and increased LVEDP
2. Myocardial contractility refers to the ability of the heart to generate force at a given preload
   • Decreased myocardial contractility is associated with decreased myocardial oxygen demand, and decreasing myocardial contractility may be beneficial in patients with CAD

Question 3

3. What are the pharmacologic alternatives for treating myocardial ischemia in this patient?

Question 4

Describe the considerations for performing surgery on patients with drug-eluting coronary stents.

Question 5

Is perioperative b-adrenergic blockade indicated for this patient

Question 6

How should this patient be monitored intraoperatively

Answer 6

○ % lead Ecg
○ Echocardiogram
○ A- line
○ CVP
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