A Research Method For Detecting Transient Myocardial Ischemia In Patients With Suspected Acute Coronary Syndrome Using Continuous ST-segment Analysis

The aim of this procedure is to identify transient myocardial ischemia among patients with suspected acute coronary syndrome, even when asymptomatic using continuous 12 lead ELECTROCARDIOGRAPHIC or ECG monitoring. Patients with suspected nons, STEMI, or unstable angina are identified as they're admitted to the emergency department, telemetry department, or cardiac intensive care unit. A 12 lead ECG Holter monitor and a routine bedside ECG monitoring system are applied.

Monitoring is maintained throughout a patient's entire hospitalization. The systems are regularly checked to ensure that the skin electrodes and lead wires have not been moved or misplaced. Finally, the stored ECG data is downloaded from the halter's flashcard to a computer for offline analysis.

Analysis of the data reveal. The presence of transient myocardial ischemia as evidenced by ST segment changes either elevation or depression during continuous 12. Lead ECG monitoring Myocardial ischemia is often clinically silent, meaning common symptoms associated with acute coronary syndrome such as chest or arm or jaw pain do not always occur.

Since many current bedside ECG monitors assess fewer than 12 ECG leads, ischemia will be missed if it occurs in those not being monitored. Today, we will show you a method that can help identify transient myocardial ischemia in both patients who may be asymptomatic and in those who may not be responding to anti ischemic therapies. This method can also be applied to the detection of arrhythmias and lengthening of QT intervals Demonstrating the procedure.

Today will be Denise Loranger, a registered nurse from my lab Prior to performing this procedure, obtain informed consent from the patient. The patient should be undergoing hospital bedside monitoring, which should have been applied and started by the patient's bedside nurse to minimize ECG artifact and noise. During Holter monitoring, a mason like or electrode configuration is used in which limb lead electrodes are placed on the torso rather than the distal extremities.

Begin by identifying landmarks on the patient's chest for accurate lead placement. If necessary. Clip chest hair at specific torso locations in order to make adequate contact with the skin electrode.

Perform this step with caution. Many of these patients receive anticoagulation therapy and are therefore prone to bleeding. Prepare the skin of the torso by wiping the skin with alcohol prep pads.

Then using gauze pads, briskly dry the skin to ensure optimal electrode contact. Using indelible ink, mark the skin electrode sites to ensure that they can be returned to the correct location if they fall off or are removed for a procedure such as an echocardiogram or chest x-ray. Here, radiolucent skin electrodes are applied to avoid removal for radiographic procedures.

Since both the hospital bedside monitor and the research Holter recorder will be used in this study, two ECG skin electrodes will be needed at each site. Before placing the electrodes, connect the lead wires to each of them. This will prevent unnecessary pressure on the chest.

Next place the electrodes on the patient's chest. Note that in women electrode V three should be placed on top of the breast tissue as shown here. Electrodes V four and V five should be placed immediately below a pendulum breast so that the breast lies on top of the electrode to ensure accurate placement and prevent motion artifact.

Once all of the electrodes have been placed, attach a lead wire cable to the Holter monitor. Insert a battery and close the monitor lid. Next arrow through the prompts and enter the patient's unique research identification number.

Select record to start ECG monitoring. The screen should display the time recording and the subject Id.Place the Holter recorder in a monitor pouch and hang the pouch around the neck with a lanyard or place the pouch in the gown pocket to obtain positional ECGs. For analysis, have the patient lie down on his or her back.

The patient should remain in the supine position quietly for at least one minute to avoid generating motion artifact. Next, have the patient roll onto his or her right side and again, have the patient remain in this position quietly for at least one minute. Finally, have the patient roll onto his or her left side, and as before, have the patient remain in this position quietly for at least one minute.

Place a torso diagram showing the correct electrode positions at the patient's bedside as a resource for the hospital staff along with some extra skin electrodes in case they need to be replaced. When the research staff are present at the hospital, check the electrode placement every two hours and at the end of the day, ensure that monitoring is maintained overnight. If any skin electrodes are removed for a procedure, they should be immediately replaced.

If the patient goes to the cardiac catheterization laboratory, connect the radiolucent lead wires to the skin electrodes so the TCG monitoring can be maintained during the catheterization procedure to ensure continuous monitoring to minimize bias. Initial assessment of the ECG data is done without knowledge of clinical data. At the completion of monitoring, load the compact flashcard from the ECG Holter recorder onto the flashcard reader of an H scribe research computer.

Select an empty folder and insert the flashcard and select connect to compact flash. Then select, acquire the data. A patient information window will appear.

Ensure the subject's unique and de-identified ID has been entered as well as the research ID number, and then select auto scan. Once analyzed, the subject's data will appear in the profile window. Ensure the data has been downloaded by assessing the expected time of monitoring.

Return to the main patient screen, select an empty folder, and erase the flashcard for future use. Using the H scribe arrhythmia analysis software, prepare the data for analysis by identifying and labeling each QRS complex. To do this, select the templates tab and choose leads two V one and V five.

Look for true ventricular beats. Then look for non ventricular beats and relabel with the correct waveform label. In this example, QRS complexes labeled as ventricular are changed to the correct label of artifact.

These same steps should be done for normal and superventricular templates as well. The H scribe software is programmed to identify transient myocardial ischemia using the standard definition, which is an ST elevation or depression of greater than or equal to 100 microvolts in two or more. ECG leads lasting for at least 60 seconds.

In this study, ST segment deviation is measured at 60 milliseconds past the J point from the patient profile screen. Scroll over to the column labeled ST and click on the box with the numbered event ST segment changes meeting. These criteria are identified and labeled by the H scribe and indicated on the analysis summary.

A 12 lead ECG of the event can be viewed and printed. Once selected human oversight to verify whether ischemia is present must be done for any computer generated event. In order to ensure false positive ST segment changes are identified correctly.

To assess ST segment trends for changes suggestive of acute ischemia, select the trend tab in the software. Then under the view tab, select switch trend tables. In this example, the ECG leads are shown on the Y axis.

By scrolling down, one can see the other leads. The time of monitoring is shown on the X axis, and by clicking the mouse specific time intervals can be selected to identify true myocardial ischemia. Any trend suggested of acute ischemia is assessed by obtaining three ECGs.

From the profile screen, select the ST event and then select the trend tab. Select view and switch trend tables to see all 12 ECG leads. Scan the trend for the location of the ST segment changes in this example ST segment elevation in leads two A, v, F, and three.

Next, click the mouse on a segment prior to the s st segment changes. To obtain a pre-event ECG. Next, select the ECG tab.

Then select the strip tool and click the left mouse button to select this ECG annotate the ECG with the statement pre-event. Add this ECG to the patient's file. Select the patient's file and then page down to the pre-event ECG.

Next, select an ECG during the maximum point of ST segment deviation. Next, select the ECG tab. Choose 12 lead.

Then select the strip tool and click the left mouse button to select this ECG annotate the ECG with the statement max event. Add this ECG to the patient's file. Select the patient's file and then page down to the max event ECG.

Next, select an ECG following the event where the S st segment deviation has returned. To baseline, select the ECG tab. Choose 12 lead view.

Then select the strip tool and click the left mouse button to select this ECG annotate the ECG with the statement end event. Add this ECG to the patient's file. Select the patient's file and then page down to the end event, ECG.

Next, examine each of the three ECGs. Any missing ECG data. Data of insufficient quality and false positive ST changes should be excluded from the analysis.

Such data is produced when monitoring is interrupted due to detached lead wires or skin electrodes as shown in this example just prior to 1400, the ST segment trend disappeared in all of the leads when the right ground electrode became detached. When the lead was replaced at 1600, monitoring resumed at which point there was an abrupt change in the ST trend. In general, abrupt and or erratic changes of the ST segment trend often indicate motion artifact and or body position changes rather than myocardial ischemia.

As shown here, this ST segment trend shows false positive ST segment changes due to intermittent ventricular pacer just prior to oh 100. The ST segment trend changes showing ST segment elevation in leads V three, V four, V five, two, A, V, F, and three. This 12 lead ECG was obtained at 0 0 51, 0 2 just prior to the trend change.

Of note, our atrial pacer spikes visible in the last four beats of the ten second rhythm strip. In lead two, this ECG was obtained at 0 1 20 39, where ventricular pacing is now present. Atrial pacing is visible as well.

The result of ventricular pacing is a change of the ST segment from predominantly negative to predominantly positive in LE V three, V four, V five two A VF resulting in ST segment elevation. However, these changes are not due to ischemia, but rather abnormal depolarization and repolarization associated with the ventricular pacer. Once the ECG data is analyzed, the patient's medical record is used to identify dates, times of treatments, medications, and symptoms during the monitoring period.

To verify the results of the ECG analysis, have a second expert analyze the ECG data using the same methodology in a designated proportion of the sample. In the present study, this is performed for 20%of the patients enrolled. In this example, transient myocardial ischemia is shown in a 68-year-old patient who presented with symptoms suggestive of acute coronary syndrome.

Of note, this patient was asymptomatic and the ST segment changes were not detected by the hospital staff. Here, a transient ST segment elevation event is illustrated. Monitoring was initiated just before 1200 and is maintained continuously until 1, 000.

The next day, a 1230, less than one hour after monitoring was initiated. ST segment elevation was seen in leads two A VF and three, which are the bottom three ST segment trends. The pre-event ECG is indicated by arrow A.The maximal ST segment changes are indicated by arrow B and the post-event ECG is indicated by arrow C.These readings show abrupt ST segment elevation in lead two A VF, and three suggestive of complete coronary occlusion that resolves after one hour.

The ST segment trend also shows two additional small but brief ST segment changes in the same leads at 1500 and just before 1800. Because these ST segment changes did not exceed the 100 microvolt threshold required for an ST event, they were not counted as transient ischemic events the following morning, a term 800, this patient was taken to the cardiac catheterization laboratory based on symptoms and elevated troponin levels of 2.5 milligrams per milliliter. A 90%lesion was found in the right coronary artery and a stent was placed.

The ST segment elevation at the end of the monitoring period occurred during the percutaneous coronary intervention procedure, including stent placement and resolved following the procedure. After watching this video, you should have a good understanding of how to initiate, maintain, and analyze 12 lead ECG data obtained with a Holter recorder in order to identify transient myocardial ischemia in patients with suspected acute coronary syndromes. While attempting this procedure, it is important to remember to perform a careful skin prep of the torso before applying the skin electrodes.

It's equally important to make frequent assessments of enrolled patients to ensure accurate and consistent electrode placement After its development. This technique paved the way for researchers in the field of cardiology to explore the usefulness of ECG technology in patients at risk for acute coronary syndromes in both in and outpatient settings.