FIGURE 4 - uploaded by Robert S Keynton
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Sample of normalized ECG tracing measured with subcutaneous (bottom) and epicardial (top) leads during normal daily activity (left) and treadmill exercise (right) in a bovine model.
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A counterpulsation device (Symphony) that works synchronously with the native heart to provide partial circulatory support was developed to treat patients with advanced heart failure. Symphony is implanted in a ‘pacemaker pocket’ without entry into the chest, and requires timing with ECG for device filling and ejection. Surface leads are limited to...
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... and epicardial ECG (2,818 thirty- second data epochs) were recorded at rest and 24 data epochs (15-20 min each) were recorded during tread- mill exercise for an aggregated total of 32 h of recorded data for all six animals (Fig. 4, left). QRS detection with subcutaneous leads demonstrated a ‡95% sensitivity and ‡95% positive predictive value (PPV) in a bovine model during normal daily activities (Table 1). QRS detection with the subcutaneous leads demonstrated a ‡90% sensitivity and ‡90% positive predictive value during treadmill exercise (Fig. 4, right). These data ...
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... data for all six animals (Fig. 4, left). QRS detection with subcutaneous leads demonstrated a ‡95% sensitivity and ‡95% positive predictive value (PPV) in a bovine model during normal daily activities (Table 1). QRS detection with the subcutaneous leads demonstrated a ‡90% sensitivity and ‡90% positive predictive value during treadmill exercise (Fig. 4, right). These data also demonstrated that during exercise, noise and motion artifacts did not signifi- cantly distort the ECG waveform or impair the QRS detection rate with subcutaneous leads. None of the subcutaneous lead pairs showed a statistically signifi- cant difference in positive predictive value or sensitiv- ity compared to the ...
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Introduction
Bleeding is the most frequent adverse event in patients with continuous flow mechanical circulatory support (CF-MCS) and has been linked to the occurrence of acquired von Willebrand syndrome (aVWS). MCS devices cause an increased shear-induced proteolysis of von Willebrand factor (VWF) by ADAMTS13, leading to aVWS. Hence, specifically...
Citations
... 49,53 The pump body is to be placed in the pacemaker-like pocket in the infraclavicular fossa of the right side of the patient and connected to the subclavian artery with a single short graft. 48,53,54 The counter-pulsation of the pump was controlled by ECG signals. 53 The Symphony, in comparison to a 40-mL IABP, was capable of providing higher overall coronary, carotid, and aortic flows and eliminating retrograde flow. ...
It has been reported that long-term use of continuous-flow mechanical circulatory support devices (CF-MCSDs) may induce complications associated with diminished pulsatility. Pulsatile-flow mechanical circulatory support devices (PF-MCSDs) have the potential of overcoming these shortcomings with the advance of technology. In order to promote in-depth understanding of PF-MCSD technology and thus encourage future mechanical circulatory support device innovations, engineering perspectives of PF-MCSD systems, including mechanical designs, drive mechanisms, working principles, and implantation strategies, are reviewed in this article. Some emerging designs of PF-MCSDs are introduced, and possible elements for next-generation PF-MCSDs are identified.
... The Symphony is a 30-mL sac that is connected to the subclavian artery through a vascular anastomosis and is implanted in a subcutaneous pocket on the right anterior chest. 14,15 Counterpulsation devices require a reliable ECG signal for timing inflation and deflation of balloon or sac [16][17][18][19][20][21][22][23] . Synchronous timing for chronic counterpulsation therapy with temporary/surface leads may be a significant clinical challenge 16 due to motion artifact and frequent need to replace surface electrodes. ...
... The LEMO connectors have a threaded enclosure as well as an extended end to provide strainrelief. 16,22,23 Experimental procedures were approved by the UofL Institutional Animal Care and Usage Committee (IACUC). ...
Counterpulsation devices (CPD) require an accurate, reliable electrocardiogram (ECG) waveform for triggering inflation and deflation. Surface electrodes are for short-term use and transvenous/epicardial leads require invasive implant procedure. A subcutaneous ECG lead configuration was developed as an alternative approach for long-term use with timing mechanical circulatory support (MCS) devices. In this study, efficacy testing was completed by simultaneously recording ECG waveforms from clinical-grade epicardial (control) and subcutaneous (test) leads in chronic ischemic heart failure (IHF) calves implanted with CPD for up to 30 days. Sensitivity and specificity of CPD triggering by R-wave detection was quantified for each lead configuration. The subcutaneous leads provided 98.9% positive predictive value and 98.9% sensitivity compared to the epicardial ECG leads. Lead migration (n=1) and fracture (n=1) were observed in only two of forty implanted leads, without adversely impacting triggering efficacy due to lead redundancy. These findings demonstrate the efficacy of subcutaneous ECG leads for long-term CPD timing and potential use as an alternative method for MCS device timing.
The ventricular electrocardiogram (v-ECG) was developed for long-term monitoring of heartbeats in patients with a left ventricular assist device (LVAD) and does not normally have the functionality necessary to detect additional heart irregularities that can progress to critical arrhythmias. Although the v-ECG has the benefits of physiological optimization and counterpulsation control, when abnormal heartbeats occur, the v-ECG does not show the distinct abnormal waveform that enables easy detection of an abnormal heartbeat among normal heartbeats on the conventional ECG. In this study, the v-ECGs of normal and abnormal heartbeats are compared with each other with respect to peak-to-peak voltage, area, and maximal slopes, and a new method to detect abnormal heartbeats is suggested. In a series of animal experiments with three porcine models (Yorkshire pigs weighing 30–40 kg), a v-ECG and conventional ECG were taken simultaneously during LVAD perfusion. Clinical experts found 104 abnormal heartbeats from the saved conventional ECG data and confirmed that the other 3159 heartbeats were normal. Almost all of the abnormal heartbeats were premature ventricular contractions (PVCs), and there was short-term tachycardia for 3 s. A personal computer was used to automatically detect abnormal heartbeats with the v-ECG according to the new method, and its results were compared with the clinicians' results. The new method found abnormal heartbeats with 90% accuracy, and less than 15% of the total PVCs were missed.
This paper describes a new implantable measurement system, further developed from an implantable measurement device implemented earlier at Tampere University of Technology (TUT), to assess the psychophysiological state of well-being of dairy-cattle. By measuring single-channel Electrocardiogram (ECG), body temperature and cattle activity we provide veterinarians and animal scientists with a tool to assess cattle stress levels and well-being. This information can, for example, be linked to cattle milk production. The new device processes the ECG signal in real-time to derive the heart rate along with a wireless radio frequency transmission of the data from the implant to a receiver device attached near or on the cattle. By collecting the data through a wireless link we are able to extend the recording period from three weeks of the earlier version of the device up to 3 months. The algorithm for the ECG peak detection is a modified version of the Pan-Tompkins algorithm optimized for cattle application with ECG recordings based on several hundred hours of data collected from previous experiments and recordings. The implantable system was tested with in vivo trials in April 2012.
Ventricular assist devices (VADs) have been used successfully as a bridge to transplant in heart failure patients by unloading ventricular volume and restoring the circulation. An artificial vasculature device (AVD) is being developed that may better facilitate myocardial recovery than VAD by controlling the afterload experienced by the native heart and controlling the pulsatile energy entering into the arterial system from the device, potentially reconditioning the arterial system properties. The AVD is a valveless, 80 ml blood chamber with a servo-controlled pusher plate connected to the ascending aorta by a vascular graft. Control algorithms for the AVD were developed to maintain any user-defined systemic input impedance (IM) including resistance, elastance, and inertial components. Computer simulation and mock circulation models of the cardiovascular system were used to test the efficacy of two control strategies for the AVD: 1) average impedance position control (AIPC)-to maintain an average value of resistance during left ventricular (LV) systole and 2) instantaneous impedance force feedback (IIFF) and position control (IIPC)-to maintain a desired value or profile of resistance and compliance. Computer simulations and mock loop tests were performed to predict resulting cardiovascular pressures, volumes, flows, and the resistance and compliance experienced by the native LV during ejection for simulated normal, failing, and recovering LV. These results indicate that the LV volume and pressure decreased, and the LV stroke volume increased with decreasing IM, resulting in an increased ejection fraction. Although the AIPC algorithm is more stable and can tolerate higher levels of sensor errors and noise, the IIFF and IIPC control algorithms are better suited to maintain any instantaneous IM or an IM profile. The developed AVD impedance control algorithms may be implemented with current VADs to promote myocardial recovery and facilitate weaning.
