Sometimes when the heart skips a beat, it is the result of outside circumstances—a good scare, a near miss, or love at first sight. Sometimes, however, when the heart misses a beat, particularly with some regularity, the implication is more literal and potentially problematic. Today, physicians often discover whether their patients’ hearts are really “broken” in the electrophysiology (EP) lab.
An electrophysiology study of the heart provides an analysis of the muscle’s electrical activity as it relates to the heartbeat. From this, physicians can often produce evidence of a signal conduction problem (if one exists) and a diagnosis. Mapping systems help to pinpoint exactly where the misfire(s) lie, while implantable devices and ablation technologies offer potential treatment.
The procedures are invasive, but less so than surgery, and they have become a valid option for both young and older patients. As the volume of protocols and patients within this modality has increased, the technology has improved.
Approximately 2 decades ago, the EP lab was the simplest, oldest, or least expensive unit in the hospital. “Today, the instrumentation and physician techniques have expanded to the point where the current EP labs are the most expensive of the cath labs with the highest level of imaging and interventional equipment,” says C. Wayne Hibbs, CCE, president of LifeStructures Technology Planning, Indianapolis.
Sick At Heart
Originally, EP studies were conducted on young patients who exhibited congenital conduction defects. “Since that time, the patient population has greatly expanded to include older adults, who have had infarctions that have disrupted the normal conduction path of the heart,” Hibbs says.
Diagnosing a conduction problem is the first of three components in the electrophysiology process, according to Hibbs. To perform an EP study, small catheters, with multiple sensors, are threaded into the heart through a vein in the groin or arm. Fluoroscopy is often used to help guide the movement; for more complex procedures, CT-guided imaging may be employed.
Once the catheters are in place, electrical signals are used to stimulate nerve conduction through the heart. Electrical data and electrocardiogram (EKG) readings are captured by the system and used to evaluate heart performance, identifying any arrhythmia, fibrillation, or other abnormality. The internal measurements yield more information than external EKGs.
Once an aberration is confirmed, the next step is to identify what specifically is wrong with the beat. To accomplish this, mapping systems are typically used to capture data simultaneously from 20 to 80 points within the heart. Measurements are taken during the heart’s natural beat and then while using electrical stimulation that overrides the patient’s rhythm.
“You can stimulate the heart from different points inside of it to see if you can identify where the miscommunication or rhythm aberration is happening,” Hibbs says.
EKG readings are used to evaluate heart performance.
The data can then be used to create a 3D image of the heart that helps to pinpoint where the problem lies. “Rather than the doctor looking at 20 EKGs running across the inside of the heart at the same time and trying to see which ones are out of sync with the others, the software will take the x-ray and plot the points of the heart,” Hibbs says.
Treatment options include implantable devices, such as pacemakers and defibrillators, as well as ablation. Both types of procedures can be performed in the EP lab and are carefully monitored using electrical and visual data.
Ablation protocols typically use radio frequency or cryogenic technologies to eliminate the spot where the conduction encounters a problem and to restore the patient’s natural rhythm. The procedure, which once took 4 to 6 hours to complete, can now be performed within an hour to an hour-and-a-half and tends to have a higher success rate, according to Hibbs.
In the Right Place
The increased efficiency and effectiveness stem from the integration of electrophysiology testing with imaging, which facilitates physician efforts to diagnose and correct abnormal heart rhythms. Electroanatomic mapping has been in use for about 10 years; the use of CT-guided imaging for roughly 5, according to Anil Yadav, MD, associate professor of clinical medicine at the Krannert Institute of Cardiology located in Indianapolis.
“I think development will continue in that direction,” Yadav says. “The technology will increasingly use imaging modalities in order to visualize the intracardiac structures in 3D and real time as we do the procedures to better guide our catheters to modify the electrical circuits even more accurately, especially in complex procedures such as ablation for atrial fibrillation and ventricular tachycardia.”
Today’s EP labs may offer observation as single plane or biplane and may or may not also incorporate stereotaxis technology. Single-plane systems display one image at a time; biplane labs offer two views simultaneously, such as the right and left side of the heart; and stereotaxis technology employs magnetic-guided catheters and remote computer control to more precisely guide and place the catheters.
Physicians tend to prefer the technologies they have been trained on and have worked with, but cost, case type, integration, footprint, and future capabilities are also criteria typically considered in the purchase of new EP technologies.
“In instances where you’re doing largely device-based procedures, meaning pacemakers and defibrillators, single plane would be just fine,” Yadav says. “But I think that if one is entertaining more complex ablative procedures, than biplane cath labs would be preferable.”
Unfortunately, however, cost can be a prohibitive factor as it increases with each upgrade. Hibbs notes that single-plane labs run $800,000 to $1.2 million, biplane systems cost $1.5 million to $2.2 million, and for stereotaxis capabilities add another $1 million.
As a result, many labs adapt for more complex procedures by using single-plane systems that can rapidly move between two views. Complex procedures also require more imaging options, such as software that can accommodate CT, MR, and ultrasound images. Like CT, MR and ultrasound have the potential to offer real-time guidance assistance, while focused ultrasound can be used for ablations.
Best Interests at Heart
“The facility itself should have the ability to use other modalities, such as magnetic resonance imaging, because the field may be headed in that direction,” Yadav says. “As long as the facility has the ability to incorporate other modalities, it will be better served because the equipment will be less likely to become obsolete.”
In addition to proper foresight, facilities should also consider the systems themselves in terms of features, ease of use, and footprint. “Stereotaxis systems require a lot of space right around the patient where the doctor would like to be standing,” Hibbs says.
Hibbs recommends that buyers evaluate the imaging and data mapping separately. “Standardization of vendors is often a selection to improve staff training and service experience. But the data mapping systems need to be evaluated on clinical performance and the cost of supplies and catheters,” he says.
Reliability, warranty, company reputation, and database integration also play a role in outfitting an EP lab. “Images are not typically saved to the PACS network,” Hibbs says. “The graphic diagnostic and therapeutic assessment and results are typically compiled into a procedure report and saved into the patient electronic medical record (EMR). The best equipment compiles the results and generates a report with the patient’s preprocedure and postprocedure conduction pathways.” Hibbs notes that the reports are not yet standardized.
Integration with the EMR has three major benefits, according to Yadav: Information capture, data security and HIPAA compliance, and reimbursement. “Future reimbursement will be directly linked to electronic medical records,” Yadav says.
More importantly, however, easy access to the information can improve both actual care and its cost by reducing the need for repeat procedures as well as the time to result. “Early access to procedures that have been done on the patient provides more efficient care to the patient,” Yadav says.
Know By Heart
Similarly, early involvement of clinical/biomedical engineering in the purchase and setup of an EP lab can help to speed installation and effective implementation. “One of the things we would always like to have input on is how the room is physically laid out,” Hibbs says.
Rather than just add EP equipment to a regular cath lab, as is typically done, biomeds can help with the layout to prevent the electrical noise that can occur with a more random setup. Because of the extra equipment and procedures, the design of an EP lab is more advanced than that for a regular cath lab.
“We spend a lot of time after the rooms are installed just trying to go in and clean up the background noise,” Hibbs says. “Whereas if we were involved earlier in the room design, we could usually eliminate a lot of those problems during construction instead of after the installation.”
Learn By Heart
Electrophysiology studies (EPS) provide information about the electrical conduction system of the heart, which controls the beat, which controls the flow of blood through the body. Normally, the heart beats 60 to 100 times per minute. Abnormal rhythms (arrhythmias or dysrhythmias) can, therefore, create problems.
Healthy hearts conduct signals in the same way. The initial stimulus originates in the sinoatrial (SA) node, also known as the “natural pacemaker,” located in the right atrium (or right upper chamber). The signal is then sent to the atrioventricular (AV) node via special conducting pathways, where it pauses before continuing down to the ventricles, the two lower chambers of the heart, through the bundle of His.
The break permits the atria to contract first, followed by the ventricles, which pushes the blood from the upper chambers of the heart into the lower chambers and eventually through the body.
Problems can occur anywhere along the conduction path and are typically classified according to origin and, in some cases, the change in pace as well. Supraventricular arrhythmias are based in the atria, while ventricular arrhythmias originate in the ventricles. Bradyarrhythmias cause beats slower than normal, while tachycardias increase the beat rhythm. The abnormality may express physical symptoms, or it may not—hence, the importance of the internal measurements provided by the EPS.
Beyond installation complications, the systems are fairly reliable. “Like anything else, you have to stay on top of it to keep them reliable,” says Ronnie McBride, CBET, clinical equipment specialist III at the Wake Forest University Baptist Medical Center in Winston-Salem, NC. “You want to make sure the hard drives are running OK and the computer is rebooted. We reboot each of our systems once a day to make sure we keep the buffers cleaned out.”
In general, although manufacturer dependent, the systems are fairly reliable. “Many of the problems that occur are due to small technical glitches and not necessarily a profound problem with the equipment—a switch is not turned a certain way or a setting is incorrect,” Yadav says.
However, when a problem does exist, repair or maintenance can be slow. “EP systems can be very heavy time consumers when you are having issues or attaching software and security patches,” McBride says.
At Wake Forest, the biomed team handles EP service and maintenance in-house, troubleshooting all problems, whether to do with cabling, grounding, noise, connections, or the computer systems. “You have a lot of heavy duty-video going on simultaneously—fluoro video, review video, real-time video—and the doctor is reviewing everything simultaneously. So we have to make sure these systems are going to present the video signals and the patient signals correctly all the time,” McBride says.
Because the systems talk over the backbone of the IS system, clinical/biomedical engineering must often work with IT. “You have to make sure the EP systems are communicating with the INW [invasive network] server, where the patient studies are stored,” McBride says.
Troubleshooting problems becomes easier with more knowledge about the systems. “You may have six or seven pieces of equipment made by six or seven different manufacturers, and putting that together to make an EP lab requires good knowledge of all the systems,” Yadav says. “Having a high-quality biomedical engineer available to help troubleshoot and integrate the information is very much required in the EP lab setting.”
McBride concurs, “If a biomed is going to be working on EP systems, my strongest advice would be to learn everything possible about them and spend as much time in cases with the doctor and the nurses while they are doing studies to learn everything about it. If you learn the clinical side, it will help with the technical.” And it will help to win the hearts of both clinicians and patients (figuratively and literally, respectively).
Renee Diiulio is a contributing writer for 24×7. For more information, contact .