Browsing by Subject "Tachycardia"

Now showing 1 - 3 of 3
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    Response of Various Conduit Arteries in Tachycardia- and Volume Overload-Induced Heart Failure
    (Public Library of Science, 2014-08-15) Lu, Xiao; Zhang, Zhen-Du; Guo, Xiaomei; Choy, Jenny Susana; Yang, Junrong; Svendsen, Mark; Kassab, Ghassan; Surgery, School of Medicine
    Although hemodynamics changes occur in heart failure (HF) and generally influence vascular function, it is not clear whether various HF models will affect the conduit vessels differentially or whether local hemodynamic forces or systemic factors are more important determinants of vascular response in HF. Here, we studied the hemodynamic changes in tachycardia or volume-overload HF swine model (created by either high rate pacing or distal abdominal aortic-vena cava fistula, respectively) on carotid, femoral, and renal arteries function and molecular expression. The ejection fraction was reduced by 50% or 30% in tachycardia or volume-overload model in four weeks, respectively. The LV end diastolic volume was increased from 65 ± 22 to 115 ± 78 ml in tachycardia and 67 ± 19 to 148 ± 68 ml in volume-overload model. Flow reversal was observed in diastolic phase in carotid artery of both models and femoral artery in volume-overload model. The endothelial function was also significantly impaired in carotid and renal arteries of tachycardia and volume-overload animals. The endothelial dysfunction was observed in femoral artery of volume-overload animals but not tachycardia animals. The adrenergic receptor-dependent contractility decreased in carotid and femoral arteries of tachycardia animals. The protein expressions of NADPH oxidase subunits increased in the three arteries and both animal models while expression of MnSOD decreased in carotid artery of tachycardia and volume-overload model. In conclusion, different HF models lead to variable arterial hemodynamic changes but similar vascular and molecular expression changes that reflect the role of both local hemodynamics as well as systemic changes in HF.
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    Subcutaneous nerve activity is more accurate than heart rate variability in estimating cardiac sympathetic tone in ambulatory dogs with myocardial infarction
    (Elsevier, 2015-07) Chan, Yi-Hsin; Tsai, Wei-Chung; Shen, Changyu; Han, Seongwook; Chen, Lan S.; Lin, Shien-Fong; Chen, Peng-Sheng; Department of Medicine, IU School of Medicine
    BACKGROUND: We recently reported that subcutaneous nerve activity (SCNA) can be used to estimate sympathetic tone. OBJECTIVE: The purpose of this study was to test the hypothesis that left thoracic SCNA is more accurate than heart rate variability (HRV) in estimating cardiac sympathetic tone in ambulatory dogs with myocardial infarction (MI). METHODS: We used an implanted radiotransmitter to study left stellate ganglion nerve activity (SGNA), vagal nerve activity (VNA), and thoracic SCNA in 9 dogs at baseline and up to 8 weeks after MI. HRV was determined based on time-domain, frequency-domain, and nonlinear analyses. RESULTS: The correlation coefficients between integrated SGNA and SCNA averaged 0.74 (95% confidence interval [CI] 0.41-1.06) at baseline and 0.82 (95% CI, 0.63-1.01) after MI (P <.05 for both). The absolute values of the correlation coefficients were significantly larger than that between SGNA and HRV analysis based on time-domain, frequency-domain, and nonlinear analyses, respectively, at baseline (P <.05 for all) and after MI (P <.05 for all). There was a clear increment of SGNA and SCNA at 2, 4, 6, and 8 weeks after MI, whereas HRV parameters showed no significant changes. Significant circadian variations were noted in SCNA, SGNA, and all HRV parameters at baseline and after MI, respectively. Atrial tachycardia (AT) episodes were invariably preceded by SCNA and SGNA, which were progressively increased from 120th, 90th, 60th, to 30th seconds before AT onset. No such changes of HRV parameters were observed before AT onset. CONCLUSION: SCNA is more accurate than HRV in estimating cardiac sympathetic tone in ambulatory dogs with MI.
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    Supraventricular Tachycardia and Sinus Rhythm with Contralateral Bundle Branch Block Patterns
    (Korean Society of Cardiology, 2014) Han, Seongwook; Miller, John M.; Das, Mithilesh Kumar; Medicine, School of Medicine
    A contralateral bundle branch block (BBB) aberration during tachycardia with a preexisting BBB strongly suggests the presence of ventricular tachycardia. We report on a middle-aged, female patient presented with wide QRS tachycardia. The patient had orthodromic atrioventricular tachycardia with a left BBB aberration in the presence of a preexisting right BBB due to an abnormal His-Purkinje system. We learned that the contralateral BBB aberration with supraventricular tachycardia could be seen when the His-Purkinje system was abnormal.