(A site map is at the bottom of each page)

[ The following is excerpted, with permission, from the Manual for Stress Echo by Larry DeBord. ]

The following is a partial listing what can go wrong in the performance of the exam. Be prepared to suffer through many "technically sub-optimal" studies, as we euphemistically and defensively call them.

• The equipment may be cabled together incorrectly, or the cables are damaged.  Look for broken connectors, frayed wires. It would seem unnecessary to warn against walking on your cables, but I have visited labs in major hospitals that did exactly that. I watched one tech cuss the equipment because it would not trigger.  She then remembered, apparently, the usual cause for this problem and very, very carefully tapped on the ECG cable's connection to the framegrabber until it appeared to make connnection.  Pulling her hands away carefully so as not to disturb the delicate link, she returned to imaging.  I wondered how long that ceremony had been observed.

• Because the ECG signal is imperfect, it can cause many unwanted triggers. Large T-waves and P-waves, for instance, can trigger the acquisition sequence as well as R-waves, giving us nonsense loops comprised of parts of diastole and parts of systole. Other unwanted triggers are provided by wandering baselines, 60 cycle noise, muscle artifact, PVC’s and pacemaker spikes. Wandering baseline and muscle artifact are the most common causes of poor triggering (or no triggering). Before beginning exercise, look at the trigger indicator to insure that the TTL is functioning properly. (This indicator may be a flashing red light on the reset button or blinking heart in the status line or blinking heart in PLW’s status box) If it isn’t, check all the leads.

• On my system the TTL is generated from the four limb leads and V5. If the R-wave isn’t twice the amplitude of the T-wave and at least 1mV in amplitude, the TTL will be inconsistent and faulty. In such cases I relocate the V5 electrode to increase the size of the R-wave. Check your system and determine which leads contribute to the TTL and experiment with relocating electrodes. Write any re-locations on the ECG print out. your electrocardiograph may have provisions for changing the leads from which the TTL is constructed.

• Obviously good skin preparation is essential. Extra time spent on this step will reduce problems.

• Place V2 high, adjacent to the left arm lead to leave the parasternal window accessible. Drop the V3, V4, V5, V6 and left leg electrodes lower on the chest wall to allow access to the apical windows. This is particularly true of tall patients, older patients and status post CABG patients who often have lower windows.

• The Pickwickian patient presents a challenge. If the electrodes are placed on his rolling, bouncing masses, we get equally rolling, bouncing baselines. We try to keep the electrodes above this problem, along the last rib just below our windows. Fortunately, their hearts are usually tipped upward with consequent higher apical windows.

• Pacemakers can be troublesome. It may be difficult to get a good tracing if the electrodes are near the unit. When the patient holds his breath, sinus rhythm may be sporadically lost to the paced rhythm causing irregular contractions that should not be used in diagnosis. With exercise, a paced rhythm frequently resolves to sinus making triggering possible.

• If the spike triggers the frame grabber early, end systole will be missed. You may solve this by using an appropriately long trigger delay at REST, but this probably will not work during exercise because, as mentioned above, the paced rhythm may convert to sinus, necessitating a quick return to the initial trigger delay.

• Use caution when interpreting the septum that has a pacer wire: the distal septum may be hypokinetic but it is due to the implanted wire, not to ischemia.

• Ectopic beats; may create erratic wall motion that can be misread.

• Bigeminy presents an interesting problem - none of the beats are "normal." One QRS follows a delay, the next comes too early. One beat may appear hyper-contractile, the other hypocontractile.

 

• Patient's failure to achieve a suitable level of stress.

• Loss of imaging windows due to patient position, respiratory interference, cardiac motion, etc. If all the apical windows disappear in the PEAK mode, take several PSSA views at various planes from proximal to apical. It is in these cases that you are happy to have the left lateral decubitus of the IMPOST stage.

• Extreme cardiac motion makes imaging difficult.

• Respiratory motion.

• Imaging technique (truncated views, too medial, too lateral, tipped posterior, tipped anterior, any of a hundred things!

• Lack of patient cooperation, inability (or refusal) to pedal, could not understand English. Stubborn, impatient, angry.

• Non-echogenic patients; obesity, smokers, COPD, barrel chest, breast implants, broken arms, broken ribs, shrapnel, overly sensitive ribs, narrow intercostal spaces, and mystical forces all contribute to the frustration.

• Bundle branch blocks can confuse the reading of the septum.

• Some papillary muscles are so large they conceal or confuse the endocardial edge and make reading difficult. This is frequently seen in the lateral wall of the AP-4 and the inferior wall of the AP-3. Sometimes very slight rotation of the transducer will eliminate the pap, allowing a clearer view of the wall’s motion

• Over-reading segments that may be "normally slow" to that individual, the distal septum of the PSLA, for example

• Technologist fatigue. A very real factor that should be considered when he/she is overworked, laboring without breaks in a windowless room, no lunch, pressures to attend to other duties, etc.

• The gods were angry, the music was all wrong, the doctor was wrong, too many phone interruptions, too many people looking over my shoulder, tech underpaid, room too hot, room too cold, trying to get out early for a dinner date, fingers wrinkling from being in gel too long, hungry, can’t think, can’t image, need to pee, wrist hurts, back hurts, head hurts, eyes hurt, butt hurts, patient had dog breath, ran out of tape, ran out of memory, ran out of gel, ran out of steam.*

*Excuses I’ve used.

  Model 1000 Supine bike stress echo bed
  Model 400 Resting and Post Treadmill Bed
  Model 500 Resting and Post Treadmill Bed
  Features, Accessories, Options
  Imaging Access Window
  The Bundle Block
  Electrical & Mechanical Features
  Ergometers
  Mattress & Vinyl colors
  Arm Support
  Delivery, Installation & Warranty
  Contact Redbud with questions
  Obtain a Bid
  Stress Echo Techniques, Literature
  Return to top of page
  Home - Table of Contents