Exercise Stress Testing & Ambulatory Monitoring

Objective 1.1.5 — Determine step-by-step procedures to perform an exercise stress test, a Holter monitor application, and an event monitor application.

This lesson is procedural. It splits into two halves: the Graded Exercise Test (GXT) done in a controlled clinical setting, and ambulatory monitoring (Holter and event monitors) that travels home with the patient.

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Part 1 — Exercise Stress Testing

What it is

The exercise stress test — also called a Graded Exercise Test (GXT) — is one of the most frequent non-invasive modalities used to assess patients with suspected or proven cardiovascular disease. Exercise is used as a physiologic stress to expose:

• Cardiovascular abnormalities not present at rest
• Adequacy of cardiac function

Used mainly to estimate prognosis and determine functional capacity, the likelihood and extent of CAD, and the effects of therapy.

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Indications

The most frequent indication is establishing the diagnosis of Coronary Artery Disease (CAD). The test provides diagnostic and prognostic information — but prognosis must be considered alongside the patient's risk status.

Patient populations & syndromes

• Asymptomatic population
• Symptomatic patients
• Silent myocardial ischemia
• Acute coronary syndromes
• Myocardial infarction
• Congestive heart failure

Evaluation of arrhythmias and devices

• Ventricular arrhythmias
• Supraventricular arrhythmias
• Atrial fibrillation
• Sinus node dysfunction
• Atrioventricular block
• Left and right bundle branch block
• Pre-excitation syndrome
• Cardiac pacemakers and ICDs (implantable cardioverter-defibrillator devices)

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Absolute Contraindications

Do not stress test if any of the following are present:

• Recent significant change in the rest ECG suggestive of significant ischemia or another acute cardiac event
• Acute systemic infection with fever, body aches
• Acute MI (within 2 days)
• High-risk unstable angina
• Uncontrolled cardiac arrhythmias
• Symptomatic severe aortic stenosis
• Uncontrolled symptomatic heart failure
• Acute pulmonary embolus or pulmonary infarction
• Acute myocarditis or pericarditis

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Physiology / Etiology

At fixed submaximal workloads below the anaerobic threshold, steady-state conditions are usually reached after the second minute of exercise. After that, heart rate, cardiac output, blood pressure, and pulmonary ventilation hold reasonably constant.

As exercise progresses:

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Exercise Protocols

In general, 8 to 12 minutes of continuous progressive exercise — long enough to elevate myocardial oxygen demand to the patient's maximal level — is optimal for diagnostic and prognostic purposes. The protocol should include a suitable recovery / cool-down period.

If the protocol is too strenuous for the patient, the test must be terminated early and is inconclusive.

Protocol comparison

Treadmill technique tip

The protocol should match the patient's physical capacity and the purpose of the test.

Do not let the patient grasp the front handrails during exercise. Functional capacity can be overestimated by as much as 20% when handrail support is permitted.

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GXT Procedure — Patient Prep

• Pre-test instructions — patients should not eat, drink, or smoke before the test (per facility guidance)
• Perform a brief history and physical examination
• Advise the patient about the risks and benefits of the procedure
• Do not perform the test on patients who are markedly hypertensive or hypotensive
• Obtain a written consent form — signed by patient, physician, and technician
• Record a standard 12-lead ECG with the patient in multiple positions
• Instruct the patient on how to perform the test
• Display a minimum of 3 leads continuously throughout the test
• Record HR, BP, and ECG at the beginning and end of each exercise stage

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During the GXT — ECG Observations

ST-segment displacement may only appear during exercise. The patient should not leave until the ECG returns to baseline.

ST Segment Depression — Thresholds

• ≥ 0.1 mV (1 mm) depression at rest = ischemia; if present, the exercise ECG becomes less specific and myocardial imaging should be considered.
• 0.5 mm depression in V2 and V3 also signifies ischemia.
• Exercise-induced ST-segment depression does not localize the site of myocardial ischemia and does not indicate which coronary artery is involved.

Upsloping ST Segments

• J-point depression is a normal finding during maximal exercise.
• Rapid upsloping ST (> 1 mV/sec) depressed < 0.15 mV (1.5 mm) at the J point → normal.
• Slow upsloping ST depressed ≥ 0.15 mV (1.5 mm) at 80 ms after the J point → abnormal.

ST-Segment Elevation

• Development of ≥ 0.10 mV (1 mm) J-point elevation is abnormal.
• Occurs more frequently in patients with anterior MI.

T-Wave Changes

T-wave morphology can be influenced by several factors during exercise — interpret in context.

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During the GXT — Non-ECG Observations

Maximal Work Capacity

One of the most important prognostic measurements obtained.

• In healthy individuals — influenced by familiarization with the equipment, level of training, and environmental conditions.
• In patients with known or suspected CAD — limited exercise capacity is associated with an increased risk of fatal and nonfatal cardiovascular events (acute coronary syndromes, stroke), regardless of age, sex, race, or abdominal adiposity.

Submaximal Exercise

Diagnostic/prognostic interpretation requires consideration of maximal work capacity. If a patient cannot reach at least 85 – 90% of age-predicted maximum, the level of exercise may be inadequate to test cardiac reserve.

Non-diagnostic test — patient unable to reach 85–90% of age-predicted max. Common in peripheral vascular disease, orthopedic limitation, neurologic impairment, or poor motivation. Pharmacologic stress imaging (vasodilator nuclear stress test, inotrope stress echo) should be considered instead.

Chest Discomfort

Helpful when diagnosing the patient's symptoms.

• The exercise level may exceed the patient's daily activity level, causing angina.
• Exercise-induced chest discomfort usually occurs after the onset of ischemic ST-segment abnormalities and may be associated with diastolic hypertension.
• In some patients, chest discomfort may be the only sign that obstructive CAD is present.
• In chronic stable angina, exercise-induced chest discomfort/pain occurs less frequently than ischemic ST depression.

Blood Pressure (BP)

Heart Rate (HR)

Heart Rate Recovery (HRR)

There is some controversy about optimal patient position in the recovery phase.

Abnormal HRR = a slow deceleration of heart rate after exercise stops. HRR = HR peak − HR one minute later

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Reasons to Terminate the GXT

• Drop in systolic BP > 10 mmHg from baseline BP
• Moderate to severe angina
• Ataxia, dizziness, near-syncope
• Cyanosis
• Technical difficulties monitoring ECG or BP
• Subject's desire to stop
• Sustained ventricular tachycardia
• ST elevation (≥ 1.0 mm) in leads without diagnostic Q waves (other than V1 or aVR)

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Emergency Equipment

A crash cart and defibrillator must be readily available at all times. The cart and supplies should be checked daily.

Appropriate medications must be on hand to treat:

• Cardiac arrhythmias
• AV block
• Hypotension
• Persistent chest pain

Start an IV line in high-risk patients.

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Part 2 — Holter and Event Monitoring

Objective — Determine step-by-step procedures for performing Holter and event monitoring tests.

Holter Monitor

Also known as an Ambulatory Electrocardiographic Recording.

A small, wearable continuous ECG recorder that captures heart rhythm while the patient performs normal daily activities. Records for a 24 – 72 hour period (specified in the physician's orders).

Indications

• Syncope
• Dizziness
• Palpitations
• Physical examination
• Arrhythmias
• Preoperative arrhythmia evaluation
• Valvular heart disease
• Post-MI patients

Patient Prep — Holter

1. Clean the electrode sites — shave any necessary chest hair.
2. Use gauze or an abrasive pad with cleanser to remove oils, lotions, and excess skin cells.
3. Hook up electrodes per the accompanying diagram.
4. Connect the cable into the monitor.
5. Insert batteries to power on the Holter and obtain a baseline reading.
6. Confirm the monitor has an ECG baseline, is on, and displays today's date before the patient leaves.

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Event Monitor

When 24–72 hours of Holter recording is insufficient to capture the cause of the patient's symptoms, longer-term monitoring is needed. Event monitors are about the size of a pager and are kept for up to 30 days.

During the wear period, digital recordings are made during symptomatic episodes and transmitted to a receiving station over standard phone lines at the patient's convenience.

Highly effective at documenting infrequent events, but recording quality is more variable than with a Holter recorder.

How loop recorders work

• Records continuously, but only a small window of time stays in memory at any moment.
• When the patient presses the event button, the current window is frozen while the device continues recording for another 30 to 60 seconds (configurable).
• Stores more than 30 seconds of ECG before the patient activates the recording (pre-event memory).

Manual vs automatic activation

• Manual systems — patient must press the button. If syncope occurs without warning and the patient cannot actuate the device, no diagnostic information is captured.
• Auto-trigger systems — device begins recording automatically when heart rate falls outside predetermined parameters.

Cell-phone-enabled systems

Some systems incorporate cellular technology that automatically notifies a central monitoring facility when conditions are met (e.g., extreme bradycardia or tachycardia). The information is then transmitted via internet/report to the physician for prompt diagnosis and treatment.

Patient Prep — Event Monitor

Same steps as the Holter — clean and shave the sites, attach electrodes per diagram, power on, verify baseline, confirm date before patient leaves.

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Patient Education — Do's and Don'ts

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High-Yield Recap

Stress test essentials

Reasons to terminate (memorize cold)

SBP drops > 10 mmHg · moderate-severe angina · ataxia / dizziness / near-syncope · cyanosis · technical issues · patient asks to stop · sustained VT · ST elevation ≥ 1 mm in non-diagnostic-Q leads (not V1 or aVR).

Ambulatory monitoring at a glance

Patient instructions (both monitors)

• ✅ Normal daily activities
• ❌ No showers, no baths, no getting wet (sweat is the only exception)
• ❌ Don't tamper with the recorder
• ❌ Don't pull or disturb the electrodes — that causes artifact