Paul Iaizzo - Profile on Academia.edu (original) (raw)

Papers by Paul Iaizzo

American Journal of Respiratory and Critical Care Medicine, 2019

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Assessments of Chamber Volumes within Perfusion‐Fixed Human Hearts: Direct Measurements versus 3D Volume Reconstructions

The FASEB Journal, 2012

Data from: American black bears perceive the risks of crossing roads

Roadways may negatively impact wildlife species through vehicular-related mortality and spatial d... more Roadways may negatively impact wildlife species through vehicular-related mortality and spatial displacement or obstruction. Here we investigated physiological responses, which provide insights into the animal’s perception of its environment. We deployed GPS-collars in combination with cardiac biologgers on American black bears (Ursus americanus; 18 bear-years) in areas with differing road densities across Minnesota, USA. We tested whether bears exhibited acute stress responses, as defined by significant increases in heart rate (HR), associated with road crossings. Maximum HR between successive telemetry locations were, on average, 13 bpm higher when bears were known to cross a road. They crossed a road, on average, once per day. Different demographic groups (males, females with and without cubs) responded similarly. We found stronger HR responses when crossing high-traffic roads relative to low-traffic in half of the bear-year combinations we sampled. Bears crossed high-traffic roads mainly at night, but low traffic roads during daylight. Bear HRs first became elevated when 73−183 meters away from roadways. Our findings suggest that roadways act as an acute stressor, but the magnitude of the stress response appears to be mild. Elevated HRs may reflect an increased vigilance and recognition of threat when preparing to cross a road. Bears’ recognition and alertness to human-related threats is adaptive for living in human-altered landscapes

Poster: Measurement of Biomechanical Properties of Tissues Under Uniaxial Stress

2021 Design of Medical Devices Conference, 2020

Brain-inspired (neuromorphic) systems realize biological neural principles with Spiking Neural Ne... more Brain-inspired (neuromorphic) systems realize biological neural principles with Spiking Neural Networks (SNN) to provide high-performing, energy-efficient frameworks for robotics, artificial intelligence, and adaptive control. The Neural Engineering Framework (NEF) brings forth a theoretical framework approach for the representation of high-dimensional mathematical constructs with spiking neurons for the implementation of functional large-scale neural networks. Here, we explore the utilization of neuromorphic adaptive control for circadian modulated cardiac pacing by examining the neuromorphic representation of high-dimensional cardiac data. For this study, we have utilized a model from a data set acquired from an American black bear during hibernation. Black bears in Minnesota will hibernate for 4-6 months without eating and drinking while losing little muscle mass and remain relatively normothermic throughout the winter [10]. In the current study, we obtained EEG and ECG data from...

Science Advances, 2020

3D printed patient-specific aortic root models with internal sensor arrays can augment the planni... more 3D printed patient-specific aortic root models with internal sensor arrays can augment the planning of medical procedures.

2018 Design of Medical Devices Conference, Apr 9, 2018

Annals of Biomedical Engineering, 2018

Ablation is a common procedure for treating patients with cancer, cardiac arrhythmia, and other c... more Ablation is a common procedure for treating patients with cancer, cardiac arrhythmia, and other conditions, yet it can cause collateral injury to the respiratory diaphragm. Collateral injury can alter the diaphragm's properties and/or lead to respiratory dysfunction. Thus, it is important to understand the diaphragm's physiologic and biomechanical properties in response to ablation therapies, in order to better understand ablative modalities, minimize complications, and maximize the safety and efficacy of ablative procedures. In this study, we analyzed physiologic and biomechanical properties of swine respiratory diaphragm muscle bundles when exposed to 5 ablative modalities. To assess physiologic properties, we performed in vitro tissue bath studies and measured changes in peak force and baseline force. To assess biomechanical properties, we performed uniaxial stress tests, measuring force-displacement responses, stress-strain characteristics, and avulsion forces. After treating the muscle bundles with all 5 ablative modalities, we observed dose-dependent sustained reductions in peak force and transient increases in baseline force-but no consistent dose-dependent biomechanical responses. These data provide novel insights into the effects of various ablative modalities on the respiratory diaphragm, insights that could enable improvements in ablative techniques and therapies.

IEEE Transactions on Biomedical Engineering, 2019

The ability to monitor catheter contact force (CF) plays a major role in assessing radiofrequency... more The ability to monitor catheter contact force (CF) plays a major role in assessing radiofrequency ablation, impacting lesion size and arrhythmia recurrence, and dictating ablation duration and/or overall patient safety. Our study sought to determine the relative CFs required to elicit reproducible monophasic action potential (MAP) recordings. Methods: The study utilized 4 swine in which: 1) median sternotomies were performed and MAPs were collected from 7 ventricular locations on the epicardial surface of each heart, and 2) a subset of endocardial signals was recorded from a reanimated heart. In these studies, the initial elicitation and then loss of stable MAP waveforms were recorded, as were their associated catheter CFs (n = 371). Results: Mean CF at the onset of stable MAP recordings was 14.2 ± 2.9g for epicardial and 16.6 ± 2.5g for endocardial locations. Across epicardial locations, no significant differences in CF were required to elicit MAPs. Additionally, endocardial and epicardial CFs for MAPs did not significantly differ for respective locations, i.e. right ventricular septum endocardial versus epicardial. In our study, the catheter CFs required to elicit MAPs were within optimal ranges previously reported for eliciting clinically viable radiofrequency ablations. Conclusion: We believe that MAP recordings could complement CF measurements with electrical data, providing additional clinical feedback for physicians performing cardiac ablation. Significance: If applied clinically, MAP recordings could potentially improve ablation outcomes in patients with cardiac arrhythmias.

IEEE Transactions on Biomedical Engineering, 2018

Ablative treatments can sometimes cause collateral injury to surrounding muscular tissue, with im... more Ablative treatments can sometimes cause collateral injury to surrounding muscular tissue, with important clinical implications. In this study, we investigated the changes in muscle physiology of the human vastus lateralis when exposed to 3 different ablation modalities: radiofrequency ablation, cryoablation, and microwave ablation. Methods: We obtained fresh vastus lateralis tissue biopsy specimens from 9 patients (age range: 29 to 73 years) who were undergoing testing for malignant hyperthermia. Using leftover tissue, we prepared 46 muscle bundles that were tested in tissue baths before and after ablation. Results: After ablation with all 3 modalities, we noted dosedependent sustained reductions in peak force (strength of contraction), as well as transient increases in baseline force (resting muscle tension). But, over the subsequent 3-hr recovery period, peak force improved, and baseline force consistently recovered to below its pre-ablation levels. Conclusion: The novel in vitro methodologies we developed to investigate changes in muscle physiology after ablation can be used to study a spectrum of ablation modalities and also to make headto-head comparisons of different ablation modalities. Significance: As the role of ablative treatments continues to expand, our findings provide unique insights into the resulting changes in muscle physiology. These insights could enhance the safety and efficacy of ablations and help individuals design and develop novel medical devices.

Conservation Physiology, 2018

Unmanned aircraft systems (UAS; i.e. 'drones') provide new opportunities for data collection in e... more Unmanned aircraft systems (UAS; i.e. 'drones') provide new opportunities for data collection in ecology, wildlife biology and conservation. Yet, several studies have documented behavioral or physiological responses to close-proximity UAS flights. We experimentally tested whether American black bears (Ursus americanus) habituate to repeated UAS exposure and whether tolerance levels persist during an extended period without UAS flights. Using implanted cardiac biologgers, we measured heart rate (HR) of five captive bears before and after the first of five flights each day. Spikes in HR, a measure of stress, diminished across the five flights within each day and over the course of 4 weeks of twice-weekly exposure. We halted flights for 118 days, and when we resumed, HR responses were similar to that at the end of the previous trials. Our findings highlight the capacity of a large mammal to become and remain habituated to a novel anthropogenic stimulus in a relatively short time (3-4 weeks). However, such habituation to mechanical noises may reduce their wariness of other human threats. Also, whereas cardiac effects diminished, frequent UAS disturbances may have other chronic physiological effects that were not measured. We caution that the rate of habituation may differ between wild and captive animals: while the captive bears displayed large initial spikes in HR change (albeit not as large as wild bears), these animals were accustomed to regular exposure to humans and mechanical noises that may have hastened habituation to the UAS.

Tissue Necrosis Associated With Chemical Ablations1

Journal of Medical Devices, 2016

Heart rhythm : the official journal of the Heart Rhythm Society, 2014

Phrenic nerve injury, both left and right, is considered a significant complication of cryoballoo... more Phrenic nerve injury, both left and right, is considered a significant complication of cryoballoon ablation for treatment of drug-refractory atrial fibrillation, and functional recovery of the phrenic nerve can take anywhere from hours to months. The purpose of this study was to focus on short periods of cooling to determine the minimal amount of cooling that may terminate nerve function related to cryo ablation. Left and/or right phrenic nerves were dissected from the pericardium and connective tissue of swine (n = 35 preparations). Nerves were placed in a recording chamber modified with a thermocouple array. This apparatus was placed in a digital water bath to maintain an internal chamber temperature of 37°C. Nerves were stimulated proximally with a 1-V, 0.1-ms square wave. Bipolar compound action potentials were recorded proximal and distal to the site of ablation both before and after ablation, then analyzed to determine changes in latency, amplitude, and duration. Temperatures ...

Imaging of a coronary artery stent implantation within an isolated human heart

Journal of cardiovascular translational research, 2012

Currently, over 16 million Americans have coronary artery disease (CAD). Consequently, almost eig... more Currently, over 16 million Americans have coronary artery disease (CAD). Consequently, almost eight million Americans have suffered a myocardial infarction (MI). One method of treating CAD and MI is the implantation of an expandable stent within a compromised artery (for example, one partially occluded by atherosclerotic plaque). In 2007 alone, approximately 560,000 Americans received a coronary stent implantation [1]. Novel imaging of the implantation of a coronary artery stent has potential educational benefits for physicians, design engineers, and patients to better understand such procedures and the devices. We employed Visible Heart® methodologies [2] to obtain endoscopic footage of a coronary artery stent implantation within a reanimated human heart. This experimental approach provides unique imaging of the device–tissue interface that can be used for device development to address related issues, such as vessel perforation and stent dislodgement, which cannot be seen as well on fluoroscopy. The endoscopic imaging modality can then be used to evaluate emerging stent technologies. Furthermore, such images could be employed as useful training tools for cardiac interventionalists as well as educational means for explaining these procedures to patients. Method

Noninvasive estimation of three-dimensional cardiac electrical activities from body surface potential maps

Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2008

A noninvasive three-dimensional (3D) cardiac electrical imaging (3DCEI) approach, which can estim... more A noninvasive three-dimensional (3D) cardiac electrical imaging (3DCEI) approach, which can estimate the location of the initiation site (IS) of activation and the resultant 3D activation sequence (AS) from body surface potential maps (BSPMs), was validated in an intact large mammalian model (swine) during acute ventricular pacing. Body surface potential mapping and intracavitary noncontact mapping (NCM) were performed simultaneously during pacing from both right ventricular (RV) sites (intramural) and left ventricular (LV) sites (endocardial). Subsequent 3DCEI analyses were performed on the measured BSPMs. In total, 5 RV and 5 LV sites from control and heart failure animals were paced. The averaged localization error of the RV and LV sites were 7.0+/-1.1 mm and 6.6+/-1.9 mm, respectively. The endocardial ASs as a subset of the estimated 3D ASs by 3DCEI were consistent with those reconstructed from the NCM system. The present experimental results demonstrate that the noninvasive 3DC...

Effect of pacing site on systolic mechanical restitution curves in the in vivo canine model

Cardiovascular engineering (Dordrecht, Netherlands), 2007

Pacing site is known to influence the contractile state of the ventricle. Non-physiologic pacing ... more Pacing site is known to influence the contractile state of the ventricle. Non-physiologic pacing sites such as the right ventricular apex (RVA) or left ventricular freewall (LVFW) have been shown to decrease the contractile state of normal myocardium, due to abnormal electrical propagation. The impact of pacing at these sites may alter mechanical restitution (MR), a fundamental cardiac property involving the electro-mechanical regulation of contraction. This, in turn, may affect cardiac function. The present study was conducted to determine if pacing site alters the time constant of MR: tau. Anesthetized canines (n = 6) were acutely paced at four sites: right atrium (RA), RVA, right ventricular septum (RVS), and LVFW. MR data was captured by the S1-S2 pacing protocol and used to create MR curves, generating a restitution time constant, tau, at each site. No significant difference in tau was found between pacing sites. A linear regression analysis of MR curves revealed that there was...

Conus Arteriosus as an Alternate Pacing Site

Journal of Medical Devices, 2013

Anatomy and Physiology of the Cardiac Conduction System

Cardiac Electrophysiology Methods and Models, 2010

The intrinsic conduction system of the heart is comprised of several specialized subpopulations o... more The intrinsic conduction system of the heart is comprised of several specialized subpopulations of cells that either spontaneously generate electrical activity (pacemaker cells) or preferentially conduct this excitation throughout the four chambers of the heart in a coordinated fashion. This chapter will discuss some of the details of this anatomy as well as physiological properties of the system. The cardiac action potential underlies signaling within the heart, and various myocyte populations elicit signature waveforms. The recording or active sensing of these action potentials is important in both research and clinical arenas. This chapter aims to provide a basic understanding of the cardiac conduction system, so the reader has a foundation for future research and reading on this topic. The information in this chapter is not comprehensive and should not be used to make decisions related to patient care.

Left-Sided Epicardial Pacing Via A Transvenous Lead Delivery

Journal of Medical Devices, 2012

Journal of the American College of Cardiology, 2013

Background: Phrenic nerve stimulation (PNS) occurs during left-sided lead implantations within th... more Background: Phrenic nerve stimulation (PNS) occurs during left-sided lead implantations within the coronary venous system in over a third of patients. An understanding of left phrenic nerve anatomy in relation to the coronary veins is essential for reducing PNS. Methods: We obtained computed tomography (CT) scans while injecting contrast into the coronary veins of 13 perfusion-fixed human hearts with the pericardium and left phrenic nerve intact. In order to visualize the location of the phrenic nerve under CT, we glued a radiopaque wire to the nerve. We then created 3D models of the anatomy, displayed in Figure 1, and measured relevant anatomical parameters (Materialise, Leuven, Belgium). Results: Table 1 presents the mean and standard deviations of various parameters relating to areas where the phrenic nerve centerline intersects with the underlying venous centerlines. The nerve intersected the closest to the left marginal veins, which are typically targeted for left-sided lead implantations. Conclusions: We found that the phrenic nerve overlaps a left marginal vein in over half of the specimens in this sample. We will continue to expand this novel anatomical database to provide further insights for PNS reduction during left-sided pacing.