Staying Connected - April 2010

ECG Leads and Leadwires

One of the products that Affinity has manufactured since its founding is ECG leadwires.


Leadwires connected to snap
electrodes on patient’s chest


Male stud on ECG electrode

ECG Leadwires make an electrical connection between an ECG electrode and a monitoring device.  In some instances, they will extend directly from the electrode to the monitor and in other instances. they may connect between the electrode and a patient cable.  In either case, the leadwires role is to accurately transmit an ECG signal.


Female snap connector attaches
to stud on patient electrode

The Patient End

The patient end of a leadwire normally connects to an ECG electrode.  ECG electrodes commonly have a male stud that is either metallic or is coated with a conductive material.  The most common connection to the electrode stud is a female snap connector.

Attached or Replaceable Leadwires

Leadwires may be permanently attached to a patient cable or may be replaceable.  In the instance where leadwires are permanently attached to the patient cable, they are typically very robust being designed to last as long as the entire cable assembly.  An advantage of this type arrangement is that leadwires do not detach and cannot become misplaced.  A cable assembly with permanently attached leadwires is often referred to as a one-piece cable.


Example of a one-piece cable assembly
with permanently attached leadwires

Replaceable leadwires may plug into a cable assembly or directly into a monitoring device.  If the monitor is either worn by the patient or can be placed within a few feet of the patient, direct connecting leadwires can be used.  If the monitoring device is more than a few feet from the patient, it is common to employ a longer cable assembly into which leadwires are plugged.


Unshielded DIN-style leadwire
being plugged into cable yoke

DIN or AAMI Plugs

Leadwires can be either shielded or unshielded.  For unshielded leadwires, it is most common for the device end to have a DIN-style safety plug.  For shielded leadwires, the AAMI-style twin-pin plug is commonly used.  Besides these two standard configurations, device manufacturers use a variety of custom or proprietary configurations.

Tensile Strength

Tensile strength is a measure of the force required to pull something such as wire to the point where it breaks.  Tensile strength is typically an important specification for leadwire.  ANSI/AAMI EC53 section 4.5.6 specifies reusable leadwires have a minimum tensile strength of 10 lbs.  Depending upon the way the leadwire will be used and how long it is expected to last, a higher tensile strength may be desirable.


Tensile strength of leadwire material
and termination to snap assembly must
be higher than snap retention force

It is common for clinical users to remove the snap connector from an electrode by pulling on the leadwire.  Because of this, it is important that the tensile strength of the leadwire material and the termination to the snap assembly be greater than the snap-off force required to disconnect the lead from an electrode.

Higher tensile strength may be achieved by using higher-strength copper alloy conductor material, tinsel conductors wrapped around a strength member, or larger diameter conductor material.  An evaluation of how the leadwire will be used in extreme situations may help determine the tensile strength required.

Durability

Leadwire durability can vary greatly from disposable wires, meant to be used once, to leadwires designed to be used for several years.  Leadwire durability is based on multiple factors including:

  • Type of conductor material – tinsel wire wrapped around a strength member offers excellent strength and flexibility
  • Conductor material – copper alloys offer increased tensile strength and flex life
  • Gauge of conductor – comparing the same material, the larger diameter the conductor, the higher the strength and durability
  • Type of shielding – a braided shield adds the greatest amount of strength.  However, in high-flex situations, a braided shield can deteriorate and abrade the jacket leading to failure
  • Jacket material used over conductor material – for a given jacket thickness, polyurethane is generally considered the most durable material
  • Termination method – additional strength and durability can be achieved by adding splice bands or adhesive to solder or crimp terminations

It is evident from the above that the durability of leadwires is influenced by a number of factors.  Because of this, the required durability of leadwires should be addressed early in the design process so that the appropriate materials and manufacturing methods can be used.

Flex Life

One measure of durability is flex life.  ANSI/AAMI EC53 specifies minimum flex life of either end of a leadwire to be 500 cycles.  If leadwires will be used several times a day, leads that only meet the minimum flex life requirement of 500 cycles would likely last far less than a year, even if used for resting ECG tests.


Leadwires used for stress testing
need to be more durable than
those used for resting ECGs

For leadwires that are permanently attached to an ECG cable that is used in a busy clinical setting such as a stress lab in a hospital, a much higher flex life will likely be required.

Electrode Connection Retention Force

Where snap connectors are used on the patient end of a leadwire, the amount of force necessary to un-snap or disconnect the leadwire from the electrode is important.  If the retention force is too low, the leadwire may disconnect inadvertently.  If the retention force is too high, the leadwire may pull loose from the snap assembly before the snap detaches from the electrode.

Sterilization

Where leadwires are required to be sterilized, the method of sterilization is important in determining what materials are appropriate.  ANSI/AAMI EC53 compliant leadwires should withstand a minimum of 10 Ethylene Oxide cycles.  PVC, TPE and TPU materials all withstand EO and Gamma sterilization well.  Of the three materials most commonly used to jacket leadwires, only TPE offers good autoclave sterilization performance.


Color coded, pre-printed inserts
comply with AHA and IEC labeling
requirements for patient leads

Labeling

Medical leadwires require labeling and marking for identification and to comply with regulatory standards.  Labeling and marking requirements are established in CFR Title 21 Sec. 820.120 “Device labeling.”  Additional labeling requirements for ECG cables and lead sets are detailed in ANSI/AAMI EC13, EC53 and IEC 60601-2-47.  Details include color coding and designations for patient electrode connections.

 One of the methods that Affinity uses to label leadwires is to use pre-printed inserts.  These colorful labels are inserted into pockets molded into snaps or banana plug connectors using a permanent adhesive.  Affinity’s proprietary inserts are a convenient way to comply with AHA and IEC labeling requirements and also simplify lead identification.

Leadwires can conform to AAMI EC53 labeling requirements by molding lead designations into appropriately colored electrode connectors.  This method is most common when the electrode connection is a snap connector.  One advantage of molded markings is that they are permanent and add no additional cost to the product.  One disadvantage of molded markings is that they are not as easy to read due to it being the same color as the molded part.

Summary

ECG leadwires are an important part of the link between a patient and a monitoring device.  Whether used independently or in conjunction with a cable assembly, leadwires should offer consistent and reliable performance.

The Affinity team has decades of experience and expertise in designing and manufacturing medical leadwires and cable assemblies.  For additional information or to discuss any aspect of medical leadwire or cable design, please contact the Affinity Engineering Team.

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Meet Cesar Jara – Customer Care Coordinator


Affinity Customer Care
Coordinator Cesar Jara

JCesar Jara began his career at Affinity just over 8 months ago as an additional Customer Care Coordinator.    He joined Candy Golding and Suzann Sitka as one of main points-of-contact for Affinity’s OEM partners.

Cesar started working for CompUSA while in school as a cashier when he was seventeen.  Six months later he was promoted to Customer Service Representative but shortly thereafter the company went out of business.  His next position was with an outdoor advertising and sign company as an Assistant Project Coordinator.  Within a few months, he was promoted to Sales Account Coordinator, but his position was eliminated when the company had to downsize due to the recession.

“Cesar is young, has a lot of energy and is enthusiastic about everything he does” said Affinity Business Development Manager, Hank Mancini.  “We interviewed a lot of good people for the Customer Care Coordinator position and are very happy that we chose Cesar.”

Discussing his job at Affinity, Cesar said, “I enjoy coming to work every day.  The reason why is because it doesn’t feel like work: it feels just like home.  Everyone is helpful and supportive as I strive to learn about our products and the needs of our OEM partners, especially my amazing supervisor, Candy Golding.”

Cesar lives in Diamond Bar with his father, mother, two sisters and one of his brothers.  He has a younger brother in the U.S. Air Force who is stationed in Okinawa, Japan.

For hobbies, Cesar enjoys paintball shooting, snowboarding and going to the driving range to hit golf balls, which he says helps reduce stress.  His idea of a great weekend is to have no worries, no stress and to not have a lot of yard work to do.


Cesar spends time in manufacturing
learning Affinity’s products

Cesar also does volunteer work as a Chaplain for the State of California.  He volunteers for both the Los Angeles County Sherriff’s Department and the Los Angeles County Probation Department where he works with men and teenagers who have had problems.  “I try to be a role model and have a positive influence in their lives” said Cesar.  “One of the greatest challenges is helping them change old habits and realize that their life is full of potential and opportunities.”

When asked what the biggest challenge he encountered when he stepped into his Customer Care role at Affinity, Cesar answered, “The language and terms!  At first, I didn’t know what everyone was talking about.  It took a while for me to learn the technical terms I needed to do my job effectively.  I am still learning every day!”

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Multi-Channel Cables


Patients often connected to more than
one device using multiple cables making
cable management a consideration

Hospital patients are often simultaneously monitored for multiple physiological parameters. This typically means that there are three or more cables connected between equipment and the patient.  Add to this an IV line and possibly an oxygen line, there can be a “tangle of wires” as one nurse described it.

One option to reduce the number of lines running to the patient is to use a cable management system where one cable carries signals from different sensors on the patient to different inputs on monitoring devices.  The typical configuration is one trunk cable with multiple monitor connectors on one end and multiple sensor connectors on the distal end.

Affinity Medical Technologies has developed and manufactures a number of variations of multi-channel cable systems including bifurcated and trifurcated versions.


Affinity Trifurcated cable
carries three discrete signals
on a single trunk cable

The design and configuration of the cable material is dictated by the number and type signals it is required to carry.  Many multi-channel cables are complex constructions with multiple discrete cables housed within the outer jacket.  They are essentially, cables within a cable.

The Affinity Medical engineering team can assist with design of cable management systems.  Contacting us early in your product development cycle allows you to take maximum advantage of our experience and expertise in cable design.

If you would like to see a sample of an Affinity bifurcated or trifurcated multi-channel cable, contact Affinity Medical Customer Care at +1 949-477-9495 or email to customercare2@affinitymed.com.

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Announcements, Information, and Trivia


Remember May 9th is Mothers Day!

Mother’s Day – the second Sunday in May

Mother’s Day will be celebrated this year on Sunday, May 9th in the United States.

Mother's Day was established by Anna Marie Jarvis, following the death of her mother on May 9, 1905.  A small service was held two years later in May in Grafton West Virginia where Anna's mother had been a Sunday School Teacher.  With the help of successful merchant, John Wanamaker, a larger service was held the following year in the auditorium of Wanamakers store in Philadelphia.

Mother’s Day was declared an official holiday by the state of West Virginia in 1910, and the rest of the states quickly followed.  On May 8, 1914, the U.S. Congress passed a law designating the second Sunday in May as Mother's Day.  On May 9, 1914, President Woodrow Wilson issued a proclamation, declaring the first national Mother's Day as a day for American citizens to show the flag in honor of those mothers whose sons had died in war.

Affinity’s 13th Anniversary

Affinity Medical will celebrate its 13th anniversary on Monday, May 17th.  We will be open as usual but will offer an extended lunch break for an employee celebration.

Heart Rhythm Society (HRS) 2010

Affinity will once again exhibit at the Heart Rhythm Society meeting which will be held in Denver.  The Technical Exposition will be open Thursday and Friday, May 13th and 14th from 9:00 AM to 5:00 PM and Saturday, the 15th, from 9:00 AM until Noon.  Affinity’s booth is number is1916.

Mary Phillipp, Bob Frank, Hank Mancini and Linda Snyder will be staffing our booth at various times and we welcome all visitors.  If you would like to schedule an appointment at a specific time, please click on the following link: hmancini@affinitymed.com to send an email.




Suzann Sitka, Cesar Jara and Candy Golding
- the Affinity Customer Care Team

Affinity Customer Care -
Hours of Operation

Affinity Medical Technologies Customer CCare specialists are available to assist you from 7:00 A.M. until 4:00 P.M., U.S. Pacific Time, except holidays.

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Affinity Medical Technologies

1732 Reynolds Ave
Irvine, CA 92614  USA
Phone: +1 949 477 9495
Fax: +1 949 477 9499
Email: CustomerCare2@affinitymed.com
Website: www.affinitymed.com