ViVitro News

 

How do I sterilize ViVitro equipment?

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You can obtain various sterility assurance levels with our products. Many customers successfully use our products for a variety of different sterile applications. The attached PDF provides a table showing all of the standard wetted materials contained in ViVitro products.


What spare parts should I have on hand for my SuperPump?

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We recommend this list of parts be stocked by a lab using the ViVitro SuperPump.

Quantity Code Description
1 SPM043.1 Piston Seal
1 SPM072 O-Ring Dash 235
1 10084 O-Ring Dash 355
1 SPM100 O-Ring Dash 70
1 9534 7/8″ ID O-Ring Shore A-70

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.

fig-1-leftfig-1-right

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

fig-2

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.

fig-3

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.

fig-4

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.

fig-5

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.

fig-6

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 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 Marshall 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!