AUTOMATIC RECORDING
Holter monitoring has been used by a number of anesthesiologists
to document the perioperative incidence of arrhythmias and ischemia. In Holter monitoring,
electrocardiographic information from one or two bipolar leads
Figure 34-25
Right bundle branch block in association with left anterior
hemiblock. Notice the RsR' pattern in V1
and the wide S in the lateral
leads. The axis of the initial QRS vector is -88 degrees. (From Thys DM,
Kaplan JA: The ECG in Anesthesia and Critical Care. New York, Churchill Livingstone,
1987.)
is recorded by a miniature magnetic tape recorder. Up to 48 hours of electrocardiographic
signals can be collected. Subsequently, the tape is processed by a playback system,
and the electrocardiographic signals are analyzed. On most modern systems, the playback
unit includes a dedicated computer for rapid analysis of the data and automatic recognition
of arrhythmias.
A significant early obstacle to the widespread use of conventional
Holter monitoring in the perioperative period was the delayed, retrospective analysis
and interpretation. This limitation was overcome by real-time Holter monitors.
They record specific electrocardiographic segments for later playback, analyze the
rhythm and ST segment in
Figure 34-26
Right bundle branch block with left posterior hemiblock.
Notice the wide S in the lateral leads and the rR' pattern in V1
. The
axis of the initial QRS vector is +166 degrees. (From Thys DM, Kaplan JA:
The ECG in Anesthesia and Critical Care. New York, Churchill Livingstone, 1987.)
Figure 34-27
Trifascicular block. The PR interval is 232 msec, and
a right bundle branch block is identified. The axis of the QRS vector is -85 degrees,
indicating a left anterior hemiblock. (Adapted from Thys DM, Kaplan JA:
The ECG in Anesthesia and Critical Care. New York, Churchill Livingstone, 1987.)
real time, and alert the user to acute perturbations.[98]
A report on validation testing of the SEER real-time digital Holter device (Marquette
Electronics) found it highly accurate in detecting ST-segment deviations.[99]
These results were obtained with digitally simulated electrocardiographic data,
and accuracy in the clinical setting remains to be validated. A different device,
the Q-Med (Q-Med, Inc., Clark, NJ), is a small, continuous electrocardiographic recording
device that has been used in patients undergoing cardiac and noncardiac surgery.
[100]
[101]
The
device records the electrocardiographic signals, performs an automatic analysis of
the electrocardiographic tracing, and sounds an alarm when ischemic changes are recognized.
Abnormal events are selectively stored and are subsequently retrievable. Despite
significant technical progress, Holter monitoring continues to be limited primarily
to clinical investigations.
