Browsing by Author "Frick, Kyle"

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    Cardiogenic shock following cardiac tamponade and Takotsubo in COVID-19
    (Future Medicine, 2020) Torabi, Asad J.; Villegas-Galaviz, Josue; Guglin, Maya; Frick, Kyle; Rao, Roopa; Medicine, School of Medicine
    Introduction: Takotsubo is often described as stress-induced cardiomyopathy and is a known cause of heart failure. Objective: Review the clinical course of a young coronavirus disease 2019 (COVID-19) patient who developed Takotsubo following cardiac tamponade. Case presentation: A 42-year-old woman presented to the emergency department with fever, altered mental status and hypoxia. She was ultimately found to be in cardiac tamponade and within 2 hours of a pericardiocentesis she developed Takotsubo and was in cardiogenic shock. Her family decided to place her on comfort measures and she died the same day. Discussion: This case illustrates the increasing number of cardiovascular complications being reported in COVID-19 and highlights the importance of clinicians to be aware of these challenges. Conclusion: Here, we report a distinct presentation of cardiogenic shock in a young COVID-19 patient. The rapid onset of her suspected Takotsubo and the severity of her disease were striking features in this case.
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    Chronic Low-Level Vagus Nerve Stimulation Reduces Stellate Ganglion Nerve Activity and Paroxysmal Atrial Tachyarrhythmias in Ambulatory Canines
    (Office of the Vice Chancellor for Research, 2011-04-08) Shen, Mark J.; Shinohara, Tetsuji; Park, Hyung-Wook; Frick, Kyle; Ice, Daniel S.; Choi, Eue-Keun; Han, Seongwook; Sharma, Rahul; Shen, Changyu; Fishbein, Michael C.; Chen, Lan S.; Lopshire, John C.; Zipes, Douglas P.; Lin, Shien-Fong; Chen, Peng-Sheng
    Introduction: Left sided low-level vagus nerve stimulation (LL-VNS) is used clinically for epilepsy and depression. We hypothesize that LL-VNS can suppress sympathetic outflow and reduce atrial tachyarrhythmias in ambulatory dogs. Methods: We implanted in 12 dogs a neurostimulator in left cervical vagus nerve and a radiotransmitter for continuous recording of left stellate ganglion nerve activities (SGNA), left thoracic vagal nerve activities (VNA) and electrocardiograms. The first 6 dogs (Group 1) underwent 1 week continuous LL-VNS. Another 6 dogs (Group 2) underwent intermittent rapid atrial pacing followed by active or sham LL-VNS on alternate weeks. Results: Integrated SGNA was significantly reduced during LL-VNS (7.8±0.9 mV-s vs. 9.4±0.9 mVs at baseline, P<0.05) in Group 1.The reduction was most apparent from 7 to 9 AM, (31% reduction, 10.8±2.5 mV-s versus 15.6±2.9 mV-s at baseline, P<0.01), along with a significantly reduced heart rate (P<0.05). SGNA-induced heart rate acceleration averaged 107.9±9.0 bpm during LL-VNS and 129.2±9.3 bpm at baseline (P<0.05). LL-VNS did not change VNA. The tyrosine hydroxylase-positive nerve structures in the left stellate ganglion were 99,684±22,257 µm2/mm2 in LL-VNS dogs and 186,561±11,383 µm2/mm2 (P<0.01) in normal control dogs. In Group 2, the frequencies of paroxysmal atrial fibrillation and atrial tachycardia during active LLVNS were 1.4±2.5/d and 8.0±5.8/d, respectively, significantly lower than during sham stimulation (9.2±6.2/d, P<0.01 and 22.0±4.4/d, P<0.001, respectively). Conclusion: LL-VNS suppresses SGNA and reduces the incidences of paroxysmal atrial tachyarrhythmias in ambulatory dogs. Significant neural remodeling of the left stellate ganglion is evident one week after cessation of chronic LL-VNS.
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    Hepatic Ischemia/Reperfusion Injury After Liver Transplantation Is Not Associated with Early Impairment of Left Ventricular Ejection Fraction
    (International Scientific Information, 2022-12-13) Rokop, Zachary P.; Frick, Kyle; Zenisek, Joseph; Kroepfl, Elizabeth; Mihaylov, Plamen; Patidar, Kavish R.; Nephew, Lauren; Mangus, Richard S.; Kubal, Chandrashekhar; Surgery, School of Medicine
    Background: Early myocardial dysfunction is a known complication following liver transplant. Although hepatic ischemia/reperfusion injury (hIRI) has been shown to cause myocardial injury in rat and porcine models, the clinical association between hIRI and early myocardial dysfunction in humans has not yet been established. We sought to define this relationship through cardiac evaluation via transthoracic echocardiography (TTE) on postoperative day (POD) 1 in adult liver transplant recipients. Material/Methods: TTE was performed on POD1 in all liver transplant patients transplanted between January 2020 and April 2021. Hepatic IRI was stratified by serum AST levels on POD1 (none: <200; mild: 200–2000; moderate: 2000–5000; severe: >5000). All patients had pre-transplant TTE as part of the transplant evaluation. Results: A total of 173 patients underwent liver transplant (LT) between 2020 and 2021 and had a TTE on POD 1 (median time to echo: 1 day). hIRI was present in 142 (82%) patients (69% mild, 8.6% moderate, 4% severe). Paired analysis between pre-LT and post-LT left ventricular ejection fraction (LVEF) of the entire study population demonstrated no significant decrease following LT (mean difference: −1.376%, P=0.08). There were no significant differences in post-LT LVEF when patients were stratified by severity of hIRI. Three patients (1.7%) had significant post-transplant impairment of LVEF (<35%). None of these patients had significant hIRI. Conclusions: hIRI after liver transplantation is not associated with immediate reduction in LVEF. The pathophysiology of post-LT cardiomyopathy may be driven by extra-hepatic triggers.
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    MiR-150 attenuates maladaptive cardiac remodeling mediated by long noncoding RNA MIAT and directly represses pro-fibrotic Hoxa4
    (American Heart Association, 2022) Aonuma, Tatsuya; Moukette, Bruno; Kawaguchi, Satoshi; Barupala, Nipuni P.; Sepúlveda, Marisa N.; Frick, Kyle; Tang, Yaoliang; Guglin, Maya; Raman, Subha V.; Cai, Chenleng; Liangpunsakul, Suthat; Nakagawa, Shinichi; Kim, Il-man; Anatomy, Cell Biology and Physiology, School of Medicine
    Background: MicroRNA-150 (miR-150) plays a protective role in heart failure (HF). Long noncoding RNA, myocardial infarction-associated transcript (MIAT) regulates miR-150 function in vitro by direct interaction. Concurrent with miR-150 downregulation, MIAT is upregulated in failing hearts, and gain-of-function single-nucleotide polymorphisms in MIAT are associated with increased risk of myocardial infarction (MI) in humans. Despite the correlative relationship between MIAT and miR-150 in HF, their in vivo functional relationship has never been established, and molecular mechanisms by which these 2 noncoding RNAs regulate cardiac protection remain elusive. Methods: We use MIAT KO (knockout), Hoxa4 (homeobox a4) KO, MIAT TG (transgenic), and miR-150 TG mice. We also develop DTG (double TG) mice overexpressing MIAT and miR-150. We then use a mouse model of MI followed by cardiac functional, structural, and mechanistic studies by echocardiography, immunohistochemistry, transcriptome profiling, Western blotting, and quantitative real-time reverse transcription-polymerase chain reaction. Moreover, we perform expression analyses in hearts from patients with HF. Lastly, we investigate cardiac fibroblast activation using primary adult human cardiac fibroblasts and in vitro assays to define the conserved MIAT/miR-150/HOXA4 axis. Results: Using novel mouse models, we demonstrate that genetic overexpression of MIAT worsens cardiac remodeling, while genetic deletion of MIAT protects hearts against MI. Importantly, miR-150 overexpression attenuates the detrimental post-MI effects caused by MIAT. Genome-wide transcriptomic analysis of MIAT null mouse hearts identifies Hoxa4 as a novel downstream target of the MIAT/miR-150 axis. Hoxa4 is upregulated in cardiac fibroblasts isolated from ischemic myocardium and subjected to hypoxia/reoxygenation. HOXA4 is also upregulated in patients with HF. Moreover, Hoxa4 deficiency in mice protects the heart from MI. Lastly, protective actions of cardiac fibroblast miR-150 are partially attributed to the direct and functional repression of profibrotic Hoxa4. Conclusions: Our findings delineate a pivotal functional interaction among MIAT, miR-150, and Hoxa4 as a novel regulatory mechanism pertinent to ischemic HF.