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Frank Starling

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https://www.readbyqxmd.com/read/29155072/a-protocol-to-study-ex-vivo-mouse-working-heart-at-human-like-heart-rate
#1
Han-Zhong Feng, Jian-Ping Jin
Genetically modified mice are widely used as experimental models to study human heart function and diseases. However, the fast rate of normal mouse heart at 400-600bpm limits its capacity of assessing kinetic parameters that are important for the physiology and pathophysiology of human heart that beats at a much slower rate (75-180bpm). To extend the value of mouse models, we established a protocol to study ex vivo mouse working hearts at a human-like heart rate. In the presence of 300μM lidocaine to lower pacemaker and conductive activities and prevent arrhythmia, a stable rate of 120-130bpm at 37°C is achieved for ex vivo mouse working hearts...
November 16, 2017: Journal of Molecular and Cellular Cardiology
https://www.readbyqxmd.com/read/29154423/the-contractile-adaption-to-preload-depends-on-the-amount-of-afterload
#2
Hanna Schotola, Samuel T Sossalla, André Renner, Jan Gummert, Bernhard C Danner, Peter Schott, Karl Toischer
AIMS: The Frank-Starling mechanism (rapid response (RR)) and the secondary slow response (SR) are known to contribute to increases contractile performance. The contractility of the heart muscle is influenced by pre-load and after-load. Because of the effect of pre-load vs. after-load on these mechanisms in not completely understood, we studied the effect in isolated muscle strips. METHODS AND RESULTS: Progressive stretch lead to an increase in shortening/force development under isotonic (only pre-load) and isometric conditions (pre- and after-load)...
November 2017: ESC Heart Failure
https://www.readbyqxmd.com/read/29061119/computer-controlled-closed-loop-drug-infusion-system-for-automated-hemodynamic-resuscitation-in-endotoxin-induced-shock
#3
Kazunori Uemura, Toru Kawada, Can Zheng, Meihua Li, Masaru Sugimachi
BACKGROUND: Hemodynamic resuscitation in septic shock requires aggressive fluid replacement and appropriate use of vasopressors to optimize arterial pressure (AP) and cardiac output (CO). Because responses to these drugs vary between patients and within patient over time, strict monitoring of patient condition and repetitive adjustment of drug dose are required. This task is time and labor consuming, and is associated with poor adherence to resuscitation guidelines. To overcome this issue, we developed a computer-controlled closed-loop drug infusion system for automated hemodynamic resuscitation in septic shock, and evaluated the performance of the system in a canine model of endotoxin shock...
October 23, 2017: BMC Anesthesiology
https://www.readbyqxmd.com/read/29060112/synergy-of-first-principles-modelling-with-predictive-control-for-a-biventricular-assist-device-in-silico-evaluation-study
#4
Vivian C A Koh, Yong Kuen Ho, Michael C Stevens, Robert F Salamonsen, Nigel H Lovell, Einly Lim
Control for dual rotary left ventricular assist devices (LVADs) used as a biventricular assist device (BiVAD) is challenging. If the control system fails, flow imbalance between the systemic and the pulmonary circulations would result, subsequently leading to ventricular suction or pulmonary congestion. With the expectation that advanced control approaches such as model predictive control could address the challenges naturally and effectively, we developed a synergistic first principles model predictive controller (MPC) for the BiVAD...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/29038355/isolated-heart-model-demonstrates-evidence-of-contractile-and-diastolic-dysfunction-in-right-ventricles-from-rats-with-sugen-hypoxia-induced-pulmonary-hypertension
#5
Evandro M Neto-Neves, Andrea L Frump, Alexandra Vayl, Jeffrey A Kline, Tim Lahm
Although extensively used for the study of left ventricular function, limited experience exists with the isolated heart model in the evaluation of right ventricular (RV) function. In particular, no published experience exists with this tool in sugen/hypoxia-induced pulmonary hypertension (SuHx-PH), a frequently used model of severe and progressive PH We sought to characterize markers of RV contractile and diastolic function in SuHx-PH and to establish their relationship with markers of maladaptive RV remodeling...
October 2017: Physiological Reports
https://www.readbyqxmd.com/read/28912258/frank-starling-mechanism-and-short-term-adjustment-of-cardiac-flow
#6
José Guilherme Chaui-Berlinck, Luiz Henrique Alves Monteiro
The Frank-Starling Law of the heart is a filling-force mechanism (FFm), a positive relationship between the distension of a ventricular chamber and its force of ejection, and such a mechanism is found across all the studied vertebrate lineages. The functioning of the cardiovascular system is usually described by means of the cardiac and vascular functions, the former related to the contractility of the heart and the latter related to the after-load imposed to the ventricle. The crossing of these functions is the so-called operation point, and the FFm is supposed to play a stabilizing role for the short-term variations in the working of the system...
September 14, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28891509/role-of-the-medullary-lateral-tegmental-field-in-sympathetic-control
#7
Michael George Zaki Ghali
The sympathetic nervous system maintains and regulates arterial pressure and tissue perfusion, via control of cardiac output and vasomotor tone. Sympatho-vascular-mediated increases in blood pressure are effected by arterioloconstriction, which causes an increase in afterload, and/or venoconstriction, which increases venous return, left ventricular preload, and consequently, the force of cardiac contraction via Frank-Starling mechanisms; withdrawal of sympathetic drive elicits reciprocal effects. Spinalization reduces mammalian arterial pressure to 40-50 mm Hg consequent to the elimination of descending medullary pre-sympathetic bulbospinal drive to preganglionic sympathetic fibers in the intermediolateral cell column of the spinal cord...
2017: Journal of Integrative Neuroscience
https://www.readbyqxmd.com/read/28881022/getting-help-from-frank-and-starling-and-coats-and-bowditch-to-augment-blood-flow-in-heat-stressed-older-adults
#8
Nisha Charkoudian
No abstract text is available yet for this article.
October 15, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28857904/in-vivo-evaluation-of-physiologic-control-algorithms-for-left-ventricular-assist-devices-based-on-left-ventricular-volume-or-pressure
#9
Gregor Ochsner, Markus J Wilhelm, Raffael Amacher, Anastasios Petrou, Nikola Cesarovic, Silvan Staufert, Barbara Röhrnbauer, Francesco Maisano, Christofer Hierold, Mirko Meboldt, Marianne Schmid Daners
Turbodynamic left ventricular assist devices (LVADs) provide a continuous flow depending on the speed at which the pump is set, and do not adapt to the changing requirements of the patient. The limited adaptation of the pump flow (PF) to the amount of venous return can lead to ventricular suction or overload. Physiologic control may compensate such situations by an automatic adaptation of the PF to the volume status of the left ventricle. We evaluated two physiologic control algorithms in an acute study with eight healthy pigs...
September 2017: ASAIO Journal: a Peer-reviewed Journal of the American Society for Artificial Internal Organs
https://www.readbyqxmd.com/read/28834724/omecamtiv-mecarbil-abolishes-length-mediated-increase-in-guinea-pig-cardiac-myofiber-ca-2-sensitivity
#10
Sampath K Gollapudi, Sherif M Reda, Murali Chandra
Omecamtiv mecarbil (OM) is a pharmacological agent that augments cardiac contractile function by enhancing myofilament Ca(2+) sensitivity. Given that interventions that increase myofilament Ca(2+) sensitivity have the potential to alter length-dependent activation (LDA) of cardiac myofilaments, we tested the influence of OM on this fundamental property of the heart. This is significant not only because LDA is prominent in cardiac muscle but also because it contributes to the Frank-Starling law, a mechanism by which the heart increases stroke volume in response to an increase in venous return...
August 22, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28734919/some-laws-were-not-made-to-be-broken-when-frank-starling-reserve-is-lost-in-heart-failure
#11
EDITORIAL
Barry A Borlaug, Yogesh N V Reddy
No abstract text is available yet for this article.
October 2017: JACC. Cardiovascular Imaging
https://www.readbyqxmd.com/read/28722695/cardiac-cycle-efficiency-and-dicrotic-pressure-variations-new-parameters-for-fluid-therapy-an-observational-study
#12
Antonio Messina, Salvatore M Romano, Eleonora Bonicolini, Davide Colombo, Gianmaria Cammarota, Marco Chiostri, Francesco Della Corte, Paolo Navalesi, Didier Payen, Stefano Romagnoli
BACKGROUND: During a fluid challenge, the changes in cardiac performance and peripheral circulatory tone are closely related to the position of the ventricle on the Frank-Starling curve. Some patients have a good haemodynamic response to a fluid challenge, others hardly any response. The early haemodynamic effects of a fluid challenge could predict the final response before the entire fluid volume has been administered. OBJECTIVE: To assess whether a multivariate logistic regression model, including pulse pressure variation (PPV), cardiac cycle efficiency (CCE), arterial elastance and the difference between the dicrotic pressure and both systolic and mean arterial pressure (SAP - Pdic and MAP - Pdic) can predict cardiac responsiveness early during a fluid challenge in comparison with the standard procedure described elsewhere...
November 2017: European Journal of Anaesthesiology
https://www.readbyqxmd.com/read/28717163/titin-mediated-thick-filament-activation-through-a-mechanosensing-mechanism-introduces-sarcomere-length-dependencies-in-mathematical-models-of-rat-trabecula-and-whole-ventricle
#13
Lorenzo Marcucci, Takumi Washio, Toshio Yanagida
Recent experimental evidence in skeletal muscle demonstrated the existence of a thick-filament mechanosensing mechanism, acting as a second regulatory system for muscle contraction, in addition to calcium-mediated thin filament regulation. These two systems cooperate to generate force, but the extent to which their interaction is relevant in physiologically contracting muscle was not yet assessed experimentally. Therefore, we included both regulatory mechanisms in a mathematical model of rat trabecula and whole ventricle...
July 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28701680/right-ventricular-end-diastolic-pressure-is-a-key-to-the-changes-in-cardiac-output-during-adaptive-servo-ventilation-support-in-patients-with-heart-failure
#14
Teruhiko Imamura, Koichiro Kinugawa
Adaptive servo-ventilation (ASV) is a recently-developed non-invasive therapy that improves the clinical course of heart failure (HF) patients. However, the precise hemodynamic response and predictors of ASV therapy remain uncertain. Overall, 69 patients with New York Heart Association HF class II-IV underwent 10-minute ASV testing along with hemodynamic studies. Among them, 21 (30%) achieved an acute response, which was defined as an increase in the cardiac index (CI) during ASV. ΔLeft ventricular end-diastolic pressure (LVEDP) did not correlate with ΔCI, whereas Δtransmural LVEDP, which was calculated by subtracting right ventricular end-diastolic pressure (RVEDP) from LVEDP, and ΔCI were positively correlated, similar to the ascending limb of Frank-Starling's law (P = 0...
August 3, 2017: International Heart Journal
https://www.readbyqxmd.com/read/28659550/significant-prognostic-value-of-acute-preload-stress-echocardiography-using-leg-positive-pressure-maneuver-for-patients-with-symptomatic-severe-aortic-stenosis-awaiting-aortic-valve-intervention
#15
Hiroki Matsuzoe, Kensuke Matsumoto, Hidekazu Tanaka, Yutaka Hatani, Keiko Hatazawa, Hiroyuki Shimoura, Junichi Ooka, Hiroyuki Sano, Keiko Ryo-Koriyama, Toshiro Shinke, Hirotsugu Yamada, Yutaka Okita, Ken-Ichi Hirata
BACKGROUND: Although aortic valve intervention is recommended for virtually all symptomatic patients with aortic stenosis (AS), how urgently the intervention should be performed remains controversial. The aim of this study was thus to determine whether the preload reserve in response to leg-positive pressure (LPP) maneuver could serve for decision-making for AS patients awaiting aortic valve intervention.Methods and Results:Sixty-eight patients with symptomatic AS, who were referred for aortic valve intervention, were recruited...
June 28, 2017: Circulation Journal: Official Journal of the Japanese Circulation Society
https://www.readbyqxmd.com/read/28639137/the-frank-starling-law-a-jigsaw-of-titin-proportions
#16
REVIEW
Vasco Sequeira, Jolanda van der Velden
The Frank-Starling Law dictates that the heart is able to match ejection to the dynamic changes occurring during cardiac filling, hence efficiently regulating isovolumetric contraction and shortening. In the last four decades, efforts have been made to identify a common fundamental basis for the Frank-Starling heart that can explain the direct relationship between muscle lengthening and its increased sensitization to Ca(2+). The term 'myofilament length-dependent activation' describes the length-dependent properties of the myofilaments, but what is(are) the underlying molecular mechanism(s) is a matter of ongoing debate...
June 2017: Biophysical Reviews
https://www.readbyqxmd.com/read/28571718/effects-of-simulated-ischemia-on-the-transmural-differences-in-the-frank-starling-relationship-in-isolated-mouse-ventricular-cardiomyocytes
#17
REVIEW
Anastasia Khokhlova, Gentaro Iribe, Yohei Yamaguchi, Keiji Naruse, Olga Solovyova
The electrical and mechanical functions of cardiomyocytes differ in relation to the spatial locations of cells in the ventricular wall. This physiological heterogeneity may change under pathophysiological conditions, providing substrates for arrhythmia and contractile dysfunctions. Previous studies have reported distinctions in the electrophysiological and mechanical responses to ischemia of unloaded subendocardial (ENDO) and subepicardial (EPI) single cardiomyocytes. In this paper, we briefly recapitulated the available experimental data on the ischemia effects on the transmural cellular gradient in the heart ventricles and for the first time evaluated the preload-dependent changes in passive and active forces in ENDO and EPI cardiomyocytes isolated from mouse hearts subjected to simulated ischemia...
May 29, 2017: Progress in Biophysics and Molecular Biology
https://www.readbyqxmd.com/read/28543923/sex-differences-in-fitness-and-cardiac-function-during-exercise-in-adolescents-with-chronic-fatigue
#18
Paolo T Pianosi, Eric Emerling, Kristin C Mara, Amy L Weaver, Philip R Fischer
Females demonstrate less robust Frank-Starling mechanism with respect to cardiac preload than males at rest. We asked whether this phenomenon would also affect cardiac performance during exercise. We hypothesized that stroke volume (SV) response to exercise would be more limited in deconditioned females such that cardiac output would be mainly rate dependent, compared with males. We conducted a chart audit of clinical exercise tests performed by adolescents with chronic fatigue. Oxygen uptake (VO2 ) was measured breath-by-breath at rest and during cycle ergometry, while cardiac output was measured by acetylene rebreathing at rest plus 2-3 sub-threshold workloads...
May 24, 2017: Scandinavian Journal of Medicine & Science in Sports
https://www.readbyqxmd.com/read/28515459/associations-between-left-ventricular-cavity-size-and-cardiac-function-and-overload-determined-by-natriuretic-peptide-levels-and-a-covariance-structure-analysis
#19
Jun Yoshida, Makoto Kawai, Kosuke Minai, Kazuo Ogawa, Takayuki Ogawa, Michihiro Yoshimura
The effects of left ventricular (LV) cavity size on cardiac function and overload have not yet been fully elucidated. We performed a covariance structure analysis and drew theoretical path models to clarify the effects of hemodynamic parameters on the stroke volume index (SVI) as a marker of cardiac function and on the plasma B-type natriuretic peptide (BNP) level as a marker of cardiac overload. We simultaneously measured various hemodynamic parameters and the BNP levels during cardiac catheterization in 1,715 inpatients of our institution...
May 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28471573/immunity-life-and-dancing-starlings-a-physician-s-perspective
#20
Dani Bercovich, Geoffrey Goodman, M Eric Gershwin
Immune function is the most basic physiological process in humans and indeed throughout the animal kingdom. Interestingly, the vast majority of textbooks of physiology do not include a chapter on immunity. Our species survival is dependent on the diversity of the immune response and the ability for antigen presentation and effector mechanisms to be enormously promiscuous. As physicians, we are likely all too aware of how brief our life span is and the myriad of diseases and events that shorten it. It is not surprising that we question where our life comes from and our relationship within the universe...
August 2016: Israel Medical Association Journal: IMAJ
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