BIOLOGY 2A03 Lecture Notes - Lecture 22: Mean Arterial Pressure, Korotkoff Sounds, Qrs Complex

Question 1. Increased peripheral edema could be caused by:

a. blocked lymph vessels

b. decreased capillary blood pressure

c. increased concentration of albumin in the blood

d. slowed heart rate

Question 2. The pulse pressure of a healthy student is most likely to be:

a. 5 mm Hg

b. 30 mm Hg

c. 95 mm Hg

d. 120 mm Hg

Question 3. beta-blockers inhibit the activity of beta-adrenergic receptors and change the function of the heart by:

a. increasing heart rate and increasing contractility

b. increasing heart rate and decreasing contractility

c. decreasing heart rate and increasing contractility

d. decreasing heart rate and decreasing contractility

Question 4. In cardiac pacemaker cells, the L-type calcium channels:

a. open during diastole

b. close when the membrane potential rises above threshold

c. are located in the cell membrane

d. pump Ca2+ ions into the sarcoplasmic reticulum

Question 5. Dr. Campbell used an elliptical trainer for 40 minutes at the gym. Although the workload remained constant, Dr. Campbell’s heart-rate rose to 150 beats per minute during the first 5 minutes, stayed at that level for the next 25 minutes and then started to rise. It was 180 beats per minute at the end of the exercise period.

What was the time interval between QRS complexes when Dr. Campbell’s heart rate was 180 beats per minute?

a. 3.3 ms

b. 33 ms

c. 333 ms

d. 3333 ms

Question 6. In the question 5 above, Dr. Campbell’s heart rate is most likely to have risen during the last 10 minutes of exercise because his:

a. lungs were becoming congested

b. atrial cells were fatigued

c. extracellular Ca2+ concentration had increased

d. hematocrit increased due to sweating

Question 7. A Physiology student is sitting still in a cold igloo. After 30 minutes, she stands up, walks slowly around the igloo, and suddenly starts to shiver.

The student preserved their core temperature while they were sitting by:

a. depressing their Frank-Starling mechanism

b. decreasing the extracellular Ca2+ concentration

c. relaxing smooth muscles in their peripheral circulation

d. increasing the resistance of arterioles in their arms and legs

Question 8. In the question 7 above, the student started to shiver soon after walking because:

a. their atria started to fibrillate

b. their ventricles started to fibrillate

c. blood moved to the periphery, became cold, and chilled the core when it returned to the chest

d. the ATP concentration in their skeletal muscles had dropped to zero

Please use the following scenario for answering the questions 9 and 10.

A newly discovered drug binds to myosin molecules in cardiac muscle (and nowhere else) and increases the probability that myosin molecules in ventricular cells will bind to actin filaments when the intracellular Ca2+ concentration rises. The drug is being tested as a potential therapy for patients with heart failure.

Question 9. This drug might help people who have low cardiac output by:

a. increasing peripheral resistance

b. increasing the force developed by ventricular cells

c. increasing the isovolumic contraction time

d. increasing heart rate

Question 10. The increased binding of cardiac myosin molecules to actin might prevent the drug from being a useful treatment by:

a. slowing ventricular relaxation

b. decreasing the duration of systole

c. decreasing resistance of capillaries

d. slowing heart rate

Medical History:
A 31 yr old man, a two pack per day smoker, presented to the emergency department complaining of sudden-onset, 10/10 crushing substernal chest pain associated with shortness of breath and diaphoresis that began 30 min prior to arrival. He had no previous history of cardiovascular disease.
Physical exam: Height 192 cm, weight 153.8 kg, BMI 41.6 kg · m–2 (class III obesity); blood pressure 178/101 mmHg, pulse 75 beats · min–1, respiratory rate 20 breaths · min–1, temperature 36.7 ∞C; normal heart sounds, lungs clear to auscultation, normal peripheral pulses
Electrocardiogram: Normal sinus rhythm, rate 72 beats · min–1; ST-segment elevation V1-V4
Chest radiograph: Normal Blood work: Elevated cTn and CK-MB; glucose normal; blood lipids: total cholesterol 200 mg · dl–1, HDL-C 45 mg · dl–1, LDL-C 134 mg · dl–1, triglycerides 104 mg · dl–1
Chest CT: No evidence of aortic dissection Echocardiogram: Left ventricular ejection fraction 45%, hypokinesis of the anteroseptal wall, borderline left ventricular enlargement, normal diastolic function, normal cardiac valves

Diagnosis:
Acute anterior wall STEMI.

Treatment:
1. Emergent cardiac catheterization (began 46 min after initial presentation to the hospital): total occlusion of the proximal left anterior descending (LAD) coronary artery, mild diffuse narrowing of the circumflex and right coronary arteries. The LAD occlusion was treated with thrombectomy, percutaneous coronary angioplasty, and placement of a drug-eluding stent, with good result.
2. Medical treatment: Aspirin, heparin, intravenous nitroglycerin, clopidogrel, abciximab, atorvastatin, carvedilol, lisinopril, nicotine patch.
3. Nicotine dependence consultation.
4. Referral to outpatient cardiac rehabilitation. Complications: None Hospital dismissal: Occurred approximately 48 h after admission; appointments made to see primary physician and to begin outpatient cardiac rehabilitation program in 5 d; follow-up blood work, ECG, and cardiology appointment in 8 wk Dismissal medications: Carvedilol, aspirin, clopidogrel, lisinopril, nicotine patch, simvastatin

Outpatient Exercise Test Results (Performed 8 D after Hospital Dismissal)
8.0 min duration (treadmill), normal blood pressure and electrocardiographic responses, peak heart rate 164 beats · min–1, V.O2peak = 3.04 L · min−1 (20.8 ml ∑ kg−1 ∑ min−1; 47% of expected), no angina reported
Exercise Prescription:
Outpatient cardiac rehabilitation program: Began 5 d after hospital dismissal; initial evaluations included assessments of neuromuscular function (normal), depression (normal), and potential sleep apnea (abnormalBerlin questionnaire, abnormal overnight oximetry resulted in referral for a sleep consultation); meeting with registered dietitian.
Exercise prescription: Goals included weight loss, increased aerobic and muscular fitness; frequency of three supervised sessions per week in cardiac rehabilitation facility plus three or four independent sessions per week (total frequency of six or seven sessions each week); average intensity using target heart rate 130 to 140 beats · min–1 (60-70% heart rate reserve), RPE 12 to 14; high-intensity intervals (to begin 2 wk after starting cardiac rehabilitation) using RPE 17, heart rate <160 beats · min–1; duration initially set at 10 to 15 min (not including warm-up, cool-down, strength training), gradually increasing to 45 to 60 min per session; types of exercise to include outdoor or treadmill walking, elliptical trainer; resistance training (to begin 2 wk after starting cardiac rehabilitation) using free weights and weight machines, initially one set of 8 to 15 slow repetitions, exercises for the major muscle groups, two or three sessions per week; lifestyle or general physical activity including walking short distances during the day, yard work, physical activity at work (return to work as restaurant equipment installer 4 wk after myocardial infarction).

Outcomes from 11 WK of Cardiac Rehabilitation Program
Medication compliance: Excellent (self-report) Exercise training: Frequency six or seven sessions per week (two or three supervised sessions per week); aerobic exercise duration 50 to 60 min per session; aerobic interval training two or three sessions per week (initially treadmill grade walking for 30 s progressing to slow jogging on treadmill for up to 4 min, three to five high-intensity intervals per session); resistance training two or three sessions per week, two or three sets of 8 to 15 repetitions, major muscle groups. Body weight: Stopped eating fast food and desserts, had more fruit, vegetables, poultry, fish; weight loss = 20.8 kg (BMI still excessive, 33.8 kg · m–2). Repeat cardiopulmonary exercise test: 10.5 min duration (treadmill), normal blood pressure and electrocardiographic responses, peak heart rate 162 beats · min–1, V.O2peak = 4.16 L · min−1 (31.2 ml ∑ kg−1 ∑ min−1; 71% of expected), 37% increase in V.O2peak (L · min−1), no angina reported. Tobacco use: One or two cigarettes daily. Blood pressure: 126/80 mmHg. Blood lipids: Total cholesterol 126 mg · dl–1, HDL-C 33 mg · dl–1, LDL-C 80 mg · dl–1, triglycerides 65 mg · dl–1. Recommendations: Stop smoking; continue medications, exercise program, and heart-healthy eating habits; continue efforts for weight loss; return appointment with cardiac rehabilitation team in 3 mo.

Discussion:
This patient was extremely young and was fortunate to realize the importance of promptly seeking medical attention with the onset of symptoms. His hospital course included standard diagnostic testing for acute myocardial infarction with subsequent timely coronary angiography with PCI of the infarct-related artery. Fortunately he did not develop serious complications and was discharged from the hospital after only 2 d. He enrolled in outpatient cardiac rehabilitation 1 wk after his MI. Of concern, he was markedly obese and may have had obstructive sleep apnea based on his abnormal Berlin questionnaire; he was referred for further evaluation in the Sleep Clinic. His course during rehabilitation was very favorable, and he did not experience post-infarction angina. He was successful in exercise and weight loss and demonstrated a remarkable increase in aerobic capacity. His challenge will be to continue taking his medications, stop smoking completely, eat a healthy diet, maintain his exercise program, and control his other coronary risk factors.

Questions:
1. What were this patient’s coronary risk factors?

2. What clinical tests were used to make the diagnosis of an acute ST-segment elevation anterior wall myocardial infarction?

3. What classes of cardiovascular medications were prescribed for this patient?

4. Compare the two cardiopulmonary exercise tests for this patient. What were the similarities? What were the differences?

5. Review the patient’s exercise prescription and program. Were the established goals achieved? Would you alter the exercise program in any fashion?

6. How effective was the patient in controlling his coronary risk factors by the time he completed 11 wk in the outpatient cardiac rehabilitation program?

7. What is his most important remaining coronary risk factor?

8. What component of the recommendations given to him at the completion of 11 wk of cardiac rehabilitation will potentially help him in sustaining his efforts at secondary prevention?

Medical History and Physycal E x a m i n a t i o n:
At age 7, Mr. AT suffered a series of seizures, and after a physical e x a m, lab tests, and electroencephalography, he was diagnosed with epilepsy and put on epileptic medication. He has gained 25 lb (11 kg) over the last 2 yr. He complains about excessive postural sway and loss of balance while walking and therefore uses his father’s cane. He has no history of smoking or alcohol consumption, but he has a familial history of diabetes. At a recent physical e x a m his low-density lipoprotein cholesterol (LDL-C) was 178 mg · dl−1, high-density lipoprotein (HDL) was 61 mg · dl−1, fasting glucose was 88 mg · dl−1, and waist circumference was 42 in. (107 cm). He is currently on Carbatrol (carbamazepine) and baclofen.

Diagnosis:
Mr. AT, now 28 yr old, was born prematurely along with his twin sister at 34 wk. His mother experienced a severe infection early in her pregnancy and was hospitalized for several days; upon birth he had an Apgar score of 4. At age 1 he was diagnosed with spastic hemiplegia.

Exercise Test Results:
Because Mr. AT is ambulatory but has balance difficulties, leg cycle ergometry was chosen as the method of aerobic exercise testing. His resting blood pressure and heart rate in a seated position were 134/80 mmHg and 82 beats · min−1, respectively. A small face mask was used to provide an adequate seal. A toe clip on his right side was used to maintain proper foot positioning on the pedals, and an adaptive glove was used to help his right hand grip the handlebar throughout the test. Mr. AT performed a 2 min warm-up without resistance. The leg cycle ergometry test began at 25 W at a cadence of 50 to 60 rpm. The protocol consisted of 2 min stages with an increase of 15 W per stage. The following data were collected during the exercise test.
The exercise test was terminated at 5:15 because of increased hip adductor spasticity and inability to maintain speed of 50 rpm, and by request of the participant because of shortness of breath. No signs of electrocardiogram abnormalities were present during the test. His V.O2 at 5:00 was 16 ml · kg−1 · min−1. The RER was <1.00 and the heart rate and V.O2 failed to reach peak. This was not a valid peak V.O2 test.
Because of the termination of the clinical leg cycle ergometry test, a more functional approach was chosen. The Timed Get Up and Go test was used as a baseline measure. This test used the following protocol.
Test Instructions
1. Starting position: Sit upright against the chair.
2. Stand up from the chair (time start).
3. Move quickly along the line toward the opposite end.
4. Touch the end and pivot back toward the chair.
5. Move quickly all the way back to the chair.
6. Pivot.
7. Sit back down (time end).
The total distance was 10 ft (3.05 m). The test was performed three times. Mr. AT’s scores were 42 s, 38 s, and 40 s. (A score over 30 s suggests a higher risk of falls.) Mr. AT used his assistive device during all testing.

Exercise Prescription:
Using the information presented in the medical history and exercise testing sections and in tables 27.9 through 27.11, develop an exercise prescription that encompasses aerobic, strength, flexibility, and neuromuscular training. Consider the different modes for each of the exercise training domains and the frequency, duration, intensity, and progression of each.

Questions:
1. How would the clinical exercise physiologist best determine the appropriate resistance levels to prescribe for this person?

2. What factors represented in the ICF model should the clinical exercise physiologist take into consideration to increase the adherence level and success of this client?

3. What fall prevention strategies should be incorporated into the exercise prescription for an individual who is at increased risk for falls?

4. Is the assistive device described in this case study appropriate for use by Mr. AT?

5. How should the clinical exercise physiologist incorporate weight loss strategies into the goals for this client?