Exercise in Chronic Disease: Cardiopulmonary and Metabolic.
Chapter 14 Case Study A Subjective Medical History
Ms. RW is a 58 yr old white woman with no prior history of heart disease. She has hypertension under good control with medications and was diagnosed with diabetes 15 yr ago. Her last fasting blood sugar was 234, and her HbA1c was 8.7. She is a former smoker (quit 10 yr ago) and leads a rather sedentary lifestyle as a computer analyst for a large local corporation. Over the past 3 mo she has started to notice increased shortness of breath when climbing two flights of stairs at work; at the top of the stairs, she feels some moderate chest pressure that resolves in a couple of minutes after she sits down at her desk. Her primary care physician sends her for a routine exercise stress test.Objective and Laboratory Data Exercise Test Results
Resting ECG: appears normal
Heart rate: 65 beats · min–1
Blood pressure: 138/92 mmHg
Heart and lung sounds: within normal limits
Ms. RW exercises on a standard Bruce protocol. At 4:30 there is some horizontal ST depression, about 1 mm in inferior and lateral leads; by peak exercise (5:20) it is about 2 mm downsloping in the same leads, and she is developing the chest pressure she described in her symptom history. ECG changes resolve by 10 min of recovery, and symptoms resolve in about 5 min of recovery.Assessment and Plan Diagnosis
Principal diagnosis: Severe two-vessel CAD. Stenting was performed to 95% proximal left anterior descending coronary artery (LAD) lesion; Ms. RW’s 75% distal left circumflex lesion was not a candidate for revascularization at the time of the procedure.
Medications: Metoprolol 50 mg twice daily, lisinopril 10 mg once daily, aspirin, Plavix, and simvastatin.Exercise Prescription
A referral for cardiac rehabilitation was placed by her cardiologist and was to start as soon as she was able to set it up after hospitalization.
- Resting heart rate: 54 beats · min–1
- Resting blood pressure: 112/64 mmHg
Initial exercise program:
- Treadmill walking = 2.0 mph (3.2 kph), 0% grade for 10 min
- Combined arm and leg ergometry = 100 W for 10 min
- Upright stationary leg ergometry = 30 to 50 W for 10 min
- Short circuit of resistance machines = one set of six exercises for 10 repetitions
Ms. RW completed 6 wk in the program at the following workloads:
- Treadmill walking = 2.7 mph (4.0 kph), 3% grade for 10 min
- Combined arm and leg ergometry = 100 to 125 W for 10 min
- Upright stationary leg ergometery = 100 to 125 W for 10 min
- Rowing = 50 to 75 W for 10 min
- Short circuit of resistance machines = two or three sets of eight exercises for 10 repetitions
- Exercise heart rate: 100 to 110 beats · min–1
- Exercise rating of perceived exertion: 12 to 14
The remainder of the program was uneventful. The patient completed a total of 12 wk from the start of the program and returned to her home exercise program and activities of daily living.Case Study Discussion Questions
- What changes may have to be made to Ms. RW’s exercise regimen in view of the residual 75% blockage in her left circumflex coronary artery?
- If she hits a plateau in her ability to increase her intensity of cardiovascular exercise that is not due to further complications with her heart, what issues may be limiting her ability to increase exercise intensity?
Case Study B Subjective Medical History
Mr. XN, a 60 yr old SE Asian male, was referred via dialysis unit for cardiac rehabilitation after PCI. He had severe dyspnea and chest pain on mild exertion. He had a 6 mo dialysis history. Body mass was 70 kg. Resting echo revealed left ventricular ejection fraction of 12%. Hemoglobin was 10g · dL–1.
Medications: Carvedilol 25 mg daily, enalnopril 20 mg once daily, aspirin, Plavix, and atorvastatin.Objective and Laboratory Data Stress Echo
Baseline: Cycled at 60 rpm starting at 10 W, increasing 10 W min–1. Finished after 6.15 min at 70 W. Peak V̇O2 12.9 mL · kg–1 · min–1.
Baseline: Severe LV dysfunction 12.1%, Diastology E/A 0.66, DT 355 ms, E/e’ 19.1Assessment and Plan Exercise Prescription and Interventions
Exercise rehabilitation, EPO administration to address anemia due to renal failure, revascularization (PCI).
- We know that mean peak V̇O2 (for a 70 kg person this is only a peak of 840 mL O2!) of heart failure patients in exercise studies is around 12-13 mL · kg–1 · min–1 or 3.7-4.0 METs* (Smart 2004 AJM).
- So moderate intensity @40-60% would require the patient to exercise at 5.0-7.2 mL · kg–1 · min–1 or 1.4-2.1 METs, which for a 70 kg person is equivalent to cycling at a low wattage of 25 W. However to obtain benefits we would like the person to cycling continually for 15-20 min, building over several weeks to perhaps 30 min. Mr. XN, however, could only manage 5-6 min continuous cycling at the outset so we adopted another approach.
- High intensity@ 85-95% would be 10.9 mL · kg–1 · min–1 (85% peak V̇O2) or 3.1 METs, this is equivalent to cycling at 42 W (illustrating the importance of having cycling equipment that can be titrated to within 2 W accuracy).
- Difference between moderate and high intensity is approximately 1.0 MET (which is relatively small).
- With recovery between intervals in HIT—to attenuate physical stress of 3 min at rest or preferably recovery at about 30-40% peak V̇O2 (initially), as Mr. XN improves we would challenge them to recover at 40-60% peak V̇O2.
- Easily below the requirements of independent living (5.5 METs) so training at high intensity will not likely expose people (with chronic disease) to efforts they are not already routinely experiencing multiple times daily.
|Base||8 wk||16 wk||52 wk|
|Minnesota Living with Heart Failure Total ScoreMax 30||27||23||20||21|
Case Study Discussion Questions
- Do you think Mr. XN would be eligible for a heart transplant? Please justify your answer.
- Do you think Mr. XN should have had CABS? Please justify your answer.
- With respect to his change in cardiac function baseline to 52 wk, do you think this is typical?
- What might explain why relative change in peak V̇O2 at 52 wk was much less than the relative change in cardiac function?
- Was the change in Minnesota score clinically significant?
|From J.K. Ehrman, P.M. Gordon, P.S. Visich, and S.J. Keteyian, Clinical Exercise Physiology Web Resource, 4th ed. (Champaign, IL: Human Kinetics, 2019).|