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How do I mount my device in the Pulse Duplicator or HiCycle?

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The Valve Mounting Procedure describes the method for moulding silicone device holder rings and mounting devices for the ViVitro Labs Pulse Duplicator, HiCycle, and RWT. This method allows the device to be mounted and removed without altering or damaging the device. For information on how to purchase pre-made, custom device holders, please contact info@vivitrolabs.com.

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How do I maintain and change bellows for the ViVitro Labs HiCycle?

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The Bellows Change Procedure describes the method for maintaining and changing bellows for the ViVitro Labs HiCycle. This method helps optimize durability testing by preventing and minimizing equipment downtime. If the recommendations in the wear prevention section are adhered to, the latest generation of bellows has been shown to last over 200 million cycles. This means the act of replacing bellows will be seldom conducted.

ViVitro Labs offers service agreements and contract routine onsite maintenance services. However, if you prefer to perform this and other regular maintenance on your HiCycle internally, the Bellows Change Procedure describes the best methods to do so. (more…)


Operations and Maintenance Instructions for Carolina Medical Electromagnetic Flowmeter Model 501 & 501D

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Use this link to download a copy of the Operations and Maintenance Instructions for Carolina Medical Electromagnetic Flowmeter Model 501 & 501D supplied with ViVitro Labs equipment.

 


FAQ: How to confirm your flow meter is working properly

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Whether you’re getting unexpected results or new to the system and want to confirm you’re calibrating the flow measurement in ViViTest correctly, there is a quick, easy check to verify the operation of the flow measuring system used with the ViVitro Labs pulse duplicator.

This step can be done after calibration or in place of performing a calibration. Set-up the pulse duplicator as it would be for flow calibration (section 6.3 of the pulse duplicator user manual). Remember to remove all air from the VIA and bubbles from ventricle chamber. There needs to be a direct connection between the SuperPump and the test fluid, with no compliant elements in the flow path.

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Figure 1. Pulse duplicator setup for flow calibration in aortic (left) or mitral (right) configuration.

Set the waveform in ViViTest to Sine50. With the system static and ViViTest in Acquire mode, re-zero the sensors. Dial up the stroke volume to your intended test conditions (typically we do this at 75 mL/stroke for 70 BPM). Confirm that the stroke volume on the SuperPump controller matches the stroke volume displayed in ViViTest within ± 0.3 mL. If these values do not match, perform the ViViTest pump calibration as per Appendix E of the Pulse Duplicator User Manual. If these values do match, acquire 10 cycles and save an acq. file. Stop the pump and check that the flow zero hasn’t drifted.

Open this acq. file in the Analyze tab. Display all waveforms and click off the other traces so only the 10 cycles of the flow waveform are displayed. Move the flow markers to isolate the positive and negative portions of the waveform. This can be done several ways, but we do this by marking the positive portion as the closing volume and the negative portion as the leakage volume – this way, the values are displayed right on the user interface, without having to open the data table to see forward flow volume.

For an aortic collection, closing volume is captured between the f2 and f3 markers and leakage volume, between f3 and f4. Ensure the f1 marker stays to the left of f2. See figure 2 below for an example. For a mitral collection, closing volume is between f1 and f2 and leakage volume is between f2 and f3. Ensure the f4 marker stays to the right of f3.

Figure 2. Flow markers and results for an aortic flow verification check.

Figure 2. Flow markers and results for an aortic flow verification check.

The volume captured by the absolute values of the positive and negative flow portions should match the controller stroke volume within ± 1.0 mL. If they do not, perform the flow calibration again. If these values still don’t match, contact us at support@vivitrolabs.com if you need assistance with troubleshooting.


Using the ViVitro Pulse Duplicator for Right Heart Testing

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This FAQ discusses configuration considerations when adapting the ViVitro Pulse Duplicator Model Left Heart flow loop to enable right heart testing.

The ViVitro Pulse Duplicator is composed of the clear acrylic Model Left Heart, SuperPump, Flow Measuring System, and ViViTest data acquisition system. This flexible piece of testing equipment simulates physiological pulsatile flow in the heart using customizable waveform control, peripheral resistance, and compliance while allowing clear device visibility as well as pressure and flow measurement and user-friendly data collection.

Initially the system was designed to mimic conditions of the left side of a heart with the intent of testing prosthetic heart valves. However, since its inception, the ViVitro Pulse Duplicator has also been customized to perform hydrodynamic testing on a variety of novel cardiovascular devices. One common custom use of the Pulse Duplicator system is for Right Heart applications.

Six areas to consider when configuring the standard ViVitro Labs Pulse Duplicator for Right Heart testing:

  • Peripheral Resistance: The pressures in the Right Heart are significantly lower than those in the Left Heart. As shown in Figure 1, in order to reach the lower pressures of right heart conditions, it may be necessary to replace the Peripheral Resistance Controller from the flow loop with a simple pinch valve.

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Figure 1. Standard Peripheral Resistance Controller (left) Pinch valve for resistance control of right heart conditions (right).

 

  • Heat Exchanger: Similar to the Peripheral Resistance, the heat exchanger may require a substitution to obtain the necessary right heart pressures. Shown in Figure 2, ViVitro Labs offers a low pressure drop heat exchanger which, while being less efficient, allows the Pulse Duplicator to achieve right heart conditions

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Figure 2. Standard heat exchanger (A) with higher efficiency and pressure drop. Low pressure drop heat exchanger (B) with lower efficiency and pressure drop.

  • Compliance: The system compliance will affect the shape of the pressure waveform, including the spread of systolic and diastolic pressures. As with the left heart, for some conditions it may be necessary to adjust compliance volumes to reach the desired pressure waveforms. See Figure 3 and the Pulse Duplicator User Manual for more details on system compliance.

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Figure 3. Compliance options for pressure waveform control. The aortic root (taller) and Windkessel (shorter) compliance tanks along with other options (not shown) may be necessary.

  • Static Head: The static pressure created by fluid in the atrium will have a large effect on the systemic pressures in the system if right heart conditions are being targeted. It may be necessary to control this height to obtain consistent results. As shown in Figure 4, a line in the atrium chamber may be useful. For hypotensive conditions this fluid should be dropped as low as possible.

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Figure 4. Controlling fluid level in the atrium chamber to control static pressure.

  • Right Ventricle Outflow Tract (RVOT): Since the glass aorta for the standard ViVitro Labs Pulse Duplicator may not simulate the desired anatomy of the RVOT, the Aortic Conduit Mount (ACM) may be an effective alternative. Essentially, the ACM can be used to mount custom ventricle outflow tracts desired to emulate test site physiology. See Figure 5 below.

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Figure 5. Model silicone aortic root mounted in the ACM accessory for the ViVitro Labs Pulse Duplicator.

  • ViViTest Software: Currently, ViViTest software (for use with the Pulse Duplicator) utilizes specific terminology for Left Heart applications, mainly in reference to valve sites (aortic and mitral). This software is still effective for Right Heart testing, as all the pressure and flow measurement locations and subsequent calculations are still relevant. Just keep in mind that references to the aortic and mitral valves apply to the pulmonic and tricuspid valves, respectively. For a screenshot of the ViViTest user interface, see Figure 6 below.

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Figure 6. ViViTest software user interface.


Connecting transducers and third party devices

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Connecting transducers and third party devices to ViVitro equipment is easy and straightforward in ViVitro Labs test equipment. We often get asked about the pressure transducers and flow meter used in our Pulse Duplicator and HiCycle products. They were selected based on performance, accuracy and relative low cost.  This allows them to be disposed of, or cleaned, when used with various blood analogues.

As the system gets modified and adopted for non-valve applications, the provided transducers may no longer be ideal. ViViTest software and Data Acquisition System are designed to accommodate any third party pressure and flow measurement tools which are capable of an analog output.

The first step in connecting a third party measurement device is to locate the correct port on the I/O module. Channel 1, 2 and 3 are for pressure signals and channel 5 is for a flow signal. The maximum signal which can be applied is +/-10VDC.

Once they are connected and powered on, start ViViTest on your PC. You will need to select the calibration tab to set the DC offset (if present) and perform a calibration. This calibration wizard will walk you through adjusting the inputs to display correctly in ViViTest and to match the known outputs of our SuperPump AR.

Once the calibration is complete, the pressure and flow data shown in the Acquire tab will be accurate and ready for collection.

If you have any questions about connecting transducers or third party devices to ViVitro equipment, or our products in general please contact support@vivitrolabs.com for more details.


TIP: Using the ViVitro Labs Pulse Duplicator for Right Heart & Full Heart Simulation

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A common question that arises regarding custom use of the Pulse Duplicator system is whether it can be used for Right Heart and Full Heart applications. This PDF by Marshal Kilduff will address this question by noting configurations to the Model Left Heart flow loop to enable right heart testing, as well as how to connect two Pulse Duplicators to allow full heart testing.


How to effectively resolve CAPA in the Accredited Lab

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QA/RA Director, Vesna Janic, and ViVitro GM, Gerry Wight, review pump head in manufacturing.

QA/RA Director, Vesna Janic, and ViVitro GM, Gerry Wight, review a VIA in manufacturing.

ViVitro Labs Inc (ViVitro) is accredited by A2LA and conforms to ISO 17025- General Requirements for the Competence of Testing and Calibration laboratories. For the current scope of ViVitro accreditation please visit A2LA website.

One of the key aspects of ISO 17025 Quality Management System (QMS) is the Corrective and Preventive Action process (CAPA). The standard requires that we have a policy (which is part of our Quality Manual) and standard operating procedure (SOP) for handling CAPAs. In addition, a clear designation of the authority for monitoring and implementing CAPAs has to be identified.

In general, any employee can create a CAPA. An important aspect of recording CAPAs is to clearly and concisely describe the issue that has occurred (corrective) or potential issue (preventive). For Management it is critical to nurture a company culture that is oriented to not only point out issues but also come up with constructive and timely solutions. Team work between Management, QA and lab personnel is integral to successful handling of CAPA. Determining root cause of the issue and outlining clear actions is definitely more successful with a team approach. However, usually QA personnel take leadership role in moving CAPA process forward.

The key for a successful CAPA system and the best way to resolve CAPA is having Management support and consistent follow up (and follow up, follow up…)  so that issues don’t slip trough the cracks. QA team plays main role providing guidance to both Management team and personnel working on CAPA.  Never give up!


Benefits of Renting or Leasing Medical Device Test Equipment

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ViVitro Labs customers can now lease, rent or purchase cardiovascular test equipment. While renting or leasing test equipment is relatively commonplace in a variety of industries, medical device manufacturers have preferred to purchase test equipment outright.  The medical industry is now discovering the benefits of leasing/renting test equipment.  These benefits include:

Try before buying

With the variety of solution offerings in the Cardio Vascular Test Equipment market, buyers want to ensure they are purchasing the best equipment for their application.  Leasing allows users to test drive a solution and ensure the product will meet their requirements before incurring capital costs.

Free up cash flow

We all know that in running a business cash flow is king.  This is nowhere more important that for small medical device start-up firms.  In many cases it will be years before entering the market place with a commercially approved device.  Maintaining good cash flow can be achieved more easily by potentially leasing or renting large capital cost equipment such as test gear.  Development projects frequently change scope and purchased equipment may not be applicable for future projects, tying up valuable capital for long periods of time.

Latest Equipment Offerings

Continuous changes to advanced medical test equipment can make the solution you purchase less capable then the latest model available from production.  By leasing or renting your solution the Research and Development team is working with the latest available system.  Typically equipment that is returned from a lease or rental agreement completion is modified to incorporate the latest capabilities from the manufacturer.  In certain cases, custom modifications can be requested when leasing medical test equipment to achieve maximum results during the lease period.

Maintenance

Let’s not forget that expenditures for test equipment do not end with a purchase.  Service and maintenance must be considered when budgeting for such a purchase.  With a lease or rental the equipment is maintained and serviced by the manufacturer.  This not only reduces budgets but it also reduces potential down time and ensures the equipment will be serviced correctly by authorized and trained individuals using approved components.


10 ways ViVitro Pulse Duplicator and HiCycle compare to equipment built in-house

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People often ask, “Why buy a ViVitro Pulse Duplicator or HiCycle when I could build something myself?  How do they compare to equipment built in-house ?” My initial reaction is always similar to that of Dominik Obrist: “It’s more complicated than you think.”  Dominik speaks from experience.

“Complicated” is actually short hand for “takes time, requires expertise, and ends up costing more.”  Here is my top 10 list of reasons why you should outsource the purchase of Pulse Duplicator and Durability testing equipment instead of doing it yourself:

  1. Ease of Use – First of all ViVitro Pulse Duplicator or HiCycle equipment will hands down be more user friendly and easier to use than any in-house system. This is especially important if you are trying to get fast, repeatable, and consistent results from technicians or students. Simplicity is an inherent design criteria from the device mounting, to the data acquisition system, and software.
  2. Reliability – When you need results in a hurry you can depend on our equipment.  Our Pulse Duplicator and HiCycle products work day in day out in countries around the world and have a proven track record of reliability. If in the unlikely event you manage to damage the equipment, see my next point…
  3. Repairs- When ViVitro Pulse Duplicator or HiCycle equipment breaks you can immediately call on extra resources to get the issue resolved right away.  For example, we inventory parts that can be easily dropped in if anything fails.  Will a homemade Pulse Duplicator or Durability Tester system give you that peace of mind? Download our Maintenance Brochure
  4. Reputation – When you report results from a ViVitro Pulse Duplicator or HiCycle system, regulators, reviewers and academics around the world know exactly what that means and how it was measured. If you do the same with your own system you will likely receive a plethora of questions trying to understand how your measurements were conducted.  Check out our citations page for a sampling of publications that use our equipment.
  5. Qualification – Many users struggle to validate that their in-house equipment is working properly. With ViVitro you can call in expertise to make sure your installed system is working to spec. Download our Qualification Brochure
  6. Training – If you have user turnover (be it employee or student), you can call in experts or access online information to get their replacements up and running right away. We invest in a variety of user manuals and training materials which in-house systems will not have. Download our Training Brochure
  7. Cost – Researchers sometimes believe that a simple home built Pulse Duplicator or Durability Tester system could be made for less.  First, factor in the time someone will spend developing their own test equipment instead of focusing on advancing their device. Combine that with the one-off machining costs for a “prototype”, and add overhead costs (which are often neglected) like documentation, user manuals etc.  ViVitro Pulse Duplicator and HiCycle equipment quickly become a very cost effective way to accelerate your development.
  8. Flexibility – If your needs change, ViVitro Pulse Duplicator and HiCycle equipment have a variety of accessories to grow with your development. Our platform of testers makes it easy to transition your device from pulsatile testing to durability testing and back. The look and feel of ViVitro Pulse Duplicator and HiCycle equipment and software is consistent from product to product. Once you know how to use one, it is intuitive to work another.  If you grow and need more capacity it can be order by phone or email.
  9. Consistency – If you ever require independent results from an ISO 17025 accredited test lab, you can come back to ViVitro to evaluate your device with no surprises due to equipment differences.
  10. Looks- As an engineer, my opinions on esthetics are somewhat suspect, but ViVitro systems look professional and impressive to visitors and investors. Home built systems often place no emphasis on appearance and deliver limited visual credibility.

Rob Fraser
Lab Manager, MSc.
ViVitro Labs Inc