A blog about what is new (and old) in the world of active implantable medical devices

Monthly Archives: May 2021

Bivacor Raises $22M to Start Human Trials of its Total Artificial Heart

Posted on by Posted in AIMD Business, Bivacor, Circulatory Support, Heart Failure (CHF)

Image Credit: Bivacor

Houston-based Bivacor, which was founded in 2008, has raised a total of $22M through a $19M series B funding round (co-led by Cormorant Asset Management and OneVentures) and a $3M NIH small-business grant from the National Heart, Lung and Blood Institute.  This money will be used to continue testing Bivacor’s Total Artificial Heart and expand the company’s workforce, as it prepares to begin its first human trials.

The device is unique in that it features a single moving part.  Two centrifugal impellers placed on a single rotor provide perfusion to the left and right sides of the body.  According to the company, active magnetic levitation provides precise, stable operation with no mechanical wear, while the device’s patented left-right flow-balancing system allows dynamic adaptation to changes in the patient’s physiology.

The centrifugal pump is powered by an external battery and controller connected via a transcutaneous cable. According to Bivacor, the device is small enough for a child but also powerful enough for a physically active adult.

Bivacor website: www.bivacor.com

FDA Publishes Guidance on Testing and Labeling Medical Devices for MRI Safety

Posted on by Posted in AIMD Business, MRI-safe

FDA published yesterday a final guidance document which provides recommendations on testing to assess the safety and compatibility of medical devices in the Magnetic Resonance (MR) Environment and the recommended format for Magnetic Resonance Imaging (MRI) Safety Information in medical device labeling.

This new guidance supersedes FDA’s 2014 guidance “Establishing Safety and Compatibility of Passive Implants in the Magnetic Resonance (MR) Environment.”  The new guidance applies to all medical devices that might be used in the MR environment. This includes all implanted medical devices, medical devices that are fastened to or carried by a patient (e.g., external insulin pump, pulse oximeter), medical devices that would reasonably be anticipated to enter the MR environment during clinical care, and all medical devices that are intended to enter the MR environment.

For active implantable medical device (AIMDs), the guidance makes reference to ISO/TS 10974 “Assessment of the safety of magnetic resonance imaging for patients with an active implantable medical device.”

Endotronix Reaches 100 Implants of the Cordella™ Pulmonary Artery Pressure Sensor

Posted on by Posted in Endotronix, Heart Failure (CHF), Sensors, Telemetry

Endotronix, a privately held company based in Illinois, recently announced that it had reached 100 implants of the Cordella™ Pulmonary Artery Pressure Sensor.  These sensors provide heart pressure readings to the Cordella™ Heart Failure System to empower clinicians to proactively adjust therapy and medications remotely without the need for office visits.

According to the announcement:

“The Cordella System enables scalable remote heart failure management and aims to increase guideline directed medical therapy (GDMT) adherence and provide early detection of worsening heart failure. The platform consists of a comprehensive patient management system that securely collects non-invasive daily health data, coupled with a seamlessly integrated, next-generation implantable PA pressure sensor. Together, they deliver the necessary information for clinicians to proactively titrate medications and improve patient care between office visits while supporting reimbursement for care delivery activities.”

The Cordella PA implantable sensor is still an investigational device.

Endotronix website: endotronix.com

 

Papers Supporting MR-Conditional IPG/Lead Mix-and-Match Presented at ISMRM 2021

Posted on by Posted in Impulse Dynamics, MRI-safe, My Portfolio

My colleagues and I presented yesterday two posters at the meeting of the International Society for Magnetic Resonance in Medicine (ISMRM).  In these papers we provide support for the idea that MR-conditional leads from one system can be matched with MR-conditional IPGs from a different system without compromising safety related to RF-induced heating .

D. Prutchi, J. Meyers, R. Shehada, RF Impedance of MR-Conditional Pacemaker Leads when Connected to Implantable Pulse Generators from Different MR-Conditional Systems, ISMRM 2021, Poster 1701_2281, Paper

In this paper,we demonstrate that at 63.87 MHz the RF impedance of IPGs is minimal relative to that of the leads, which dominates the overall impedance of the implantable system. Accordingly, mixed hybrid systems composed of MR-Conditional leads and any MR-Conditional IPG are expected to have a comparable overall impedance and consequently produce the same RF-induced heating as their corresponding original systems specified by the manufacturers.

J. Meyers, D. Prutchi, R. Shehada, Input Impedance Comparison of MR-Conditional Cardiac Implantable Pulse Generators at the 1.5T MR Frequency of 63.87 MHz, ISMRM 2021, Poster 2311, Paper

In this study, we measured the impedance at 63.87 MHz of several MR-conditional IPGs from different manufacturers to assess the role of the IPG in determining the RF-induced heating at the lead electrodes.  From the narrow impedance range measured, we suggest that the IPG component of an MR-Conditional system could be interchanged without compromising safety.

We also presented the following poster:

D. Prutchi, J. Meyers, R. Shehada, Importance of Pacemaker Lead Preconditioning for MR Safety In-Vitro Studies, ISMRM 2021, Poster 2282, Paper

In this study we investigated the change in the RF filtering characteristics of the leads of active implantable medical devices (AIMDs) as body fluids seep into the leads during the initial post implant period.  Our findings indicate that the RF characteristics change dramatically with fluid absorption, making it necessary to precondition the leads by soaking in isotonic saline solution to simulate the in-vivo scenario when conducting in-vitro MR safety testing. Furthermore, leads designed with RF-attenuating lumped inductances must consider the effect of fluid absorption on changing the peak RF attenuation frequency.

Intermedics’ 1995 Res-Q ACD

Posted on by Posted in Cardioversion/Defibrillation, History, Intermedics (1974-1999), Museum, Tachycardia

In December of 1995 FDA approved the Res-Q ACD.  This was Intermedics’ first implantable defibrillator.  The abdominal-implant device was a relatively late-comer, and large for the time (230 g), but it did offer the highest energy output (40 Joules).  Another unique feature of the ResQ device was that it provided a connectorized sterile package which allowed complete pre-implant testing, thereby reducing the need for additional equipment.

Acknowledgement:  Thanks to Tim Carroll and Randy Armstrong at Velentium for allowing me to take a picture of this device in their collection.

Intec’s AID – The Very First Implantable Defibrillators

Posted on by Posted in Cardioversion/Defibrillation, History, Museum, Stephen Heilman, Tachycardia

Intec AID-B. (c) 2021 David Prutchi, PhD.

Conceived by physicians Michel Mirowski and Morton Mower, and supported by Dr. Stephen Heilman, the first automatic implantable defibrillator was developed and manufactured under the name of “AID” by Medrad/Intec Systems in Pittsburgh, PA.

It was encased in titanium and hermetically sealed with a laser beam weld. It had a volume of 145 ml and weighed 250 gm. The device was powered by lithium batteries which had a projected monitoring life of 3 years or a discharge capability of 100 shocks.

The ICD was designed to detect ventricular fibrillation and sinusoidal ventricular tachycardia, and it attempted to using a truncated exponential 25 Joules pulse.  The device could recycle three times during a single episode with the third and fourth pulses delivered at 30 Joules.

The device was meant to be connected to electrodes made from titanium and coated with silicone rubber. One defibrillating electrode was located intravascularly in the superior vena cava (SVC) at the right atrial junction. The second electrode had the configuration of a rectangular patch or a cup and was positioned over the cardiac apex.

First implants of the device were conducted at the Johns Hopkins Hospital in Baltimore in 1980.  These devices were not programmable and manufactured on an individual basis.  The AID was then improved with rate-counting circuitry and could synchronize shocks with the R-wave.  Efforts were also made to reduce the recycling time after a failed shock.  The new device was called the AID-B (shown in the picture), but was still manufactured according to individual specifications.

Circuitry of the AID-B implantable defibrillator. From: PJ Troup, “Implantable Cardioverters and Defibrillators”, Current Problems in Cardiology, Volume 14, Issue 12, December 1989.

Acknowledgement:  Thanks to Tim Carroll and Randy Armstrong at Velentium for allowing me to take a picture of this device in their collection.