FEASIBILITY OF A NEW NON INVASIVE METHOD FOR THE EVALUATION OF CORONARY BLOOD FLOW IN CORONARIES: TRANSTHORACIC CONVERGENT COLOR DOPPLER MODE ALONG WITH PHARMACOLOGICALLY INDUCED HEART RATE LOWERING

alpha-Adrenergic control of the oxygen delivery to the myocardium during exercise was investigated in eight conscious dogs instrumented for chronic measurements of coronary blood flow, left ventricular (LV) pressure, aortic blood pressure, and heart rate and sampling of arterial and coronary sinus blood. After alpha-adrenergic receptor blockade a standard exercise load elicited a significantly greater increase in heart rate, rate of change of LV pressure (LV dP/dt), LV dP/dt/P, and coronary blood flow than was elicited in the unblocked state. In contrast to the response pattern during control exercise, there was no significant change in coronary sinus oxygen tension (PO2), myocardial arteriovenous oxygen difference, and myocardial oxygen delivery-to-oxygen consumption ratio. It is concluded that the normal relationship between myocardial oxygen supply and oxygen demand is modified during exercise after alpha-adrenergic blockade, whereby oxygen delivery is better matched to oxygen consumption. These results indicate that the increase in coronary blood flow and oxygen delivery to the myocardium during normal exercise is limited by alpha-adrenergic vasoconstriction.

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Computational Analysis of Coronary Blood Flow: The Role of Asynchronous Pacing and Arrhythmias

Mathematics ◽

10.3390/math8081205 ◽

2020 ◽

Vol 8 (8) ◽

pp. 1205

Author(s):

Timur Gamilov ◽

Philipp Kopylov ◽

Maria Serova ◽

Roman Syunyaev ◽

Andrey Pikunov ◽

...

Keyword(s):

Heart Rate ◽

Blood Flow ◽

Coronary Blood Flow ◽

Long Qt Syndrome ◽

Premature Ventricular Contraction ◽

Cardiac Pacing ◽

Long Qt ◽

Computational Evaluation ◽

Qt Syndrome

In this work we present a one-dimensional (1D) mathematical model of the coronary circulation and use it to study the effects of arrhythmias on coronary blood flow (CBF). Hydrodynamical models are rarely used to study arrhythmias’ effects on CBF. Our model accounts for action potential duration, which updates the length of systole depending on the heart rate. It also includes dependency of stroke volume on heart rate, which is based on clinical data. We apply the new methodology to the computational evaluation of CBF during interventricular asynchrony due to cardiac pacing and some types of arrhythmias including tachycardia, bradycardia, long QT syndrome and premature ventricular contraction (bigeminy, trigeminy, quadrigeminy). We find that CBF can be significantly affected by arrhythmias. CBF at rest (60 bpm) is 26% lower in LCA and 22% lower in RCA for long QT syndrome. During bigeminy, trigeminy and quadrigeminy, respectively, CBF decreases by 28%, 19% and 14% with respect to a healthy case.

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Nutritional circulation in the heart -I. Effect of change in heart rate on myocardial oxygen consumption and nutritional circulation with constant total coronary blood flow

Life Sciences ◽

10.1016/0024-3205(69)90044-7 ◽

1969 ◽

Vol 8 (21) ◽

pp. 1151-1162 ◽

Cited By ~ 2

Author(s):

P. Somani ◽

A.R. Laddu ◽

H.F. Hardman

Keyword(s):

Heart Rate ◽

Blood Flow ◽

Oxygen Consumption ◽

Coronary Blood Flow ◽

Myocardial Oxygen Consumption

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Design of a phantom device with a safety system based on a non-invasive method of monitoring blood flow within an operator's arm

10.1109/mmar49549.2021.9528428 ◽

2021 ◽

Author(s):

Kamil Kamienski ◽

Maciej Recko ◽

Kazimierz Dzierzek

Keyword(s):

Blood Flow ◽

Safety System ◽

Non Invasive ◽

Invasive Method

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Trends in Heart Rate and Heart Rate Variability during Pregnancy and Three Months Postpartum: Continuous Monitoring in a Free-Living Context (Preprint)

10.2196/preprints.33458 ◽

2021 ◽

Author(s):

Fatemeh Sarhaddi ◽

Iman Azimi ◽

Anna Axelin ◽

Hannakaisa Niela-Vilen ◽

Pasi Liljeberg ◽

...

Keyword(s):

Heart Rate ◽

Heart Rate Variability ◽

Pregnant Women ◽

Time Domain ◽

Second Trimester ◽

Third Trimester ◽

Non Invasive ◽

The Third ◽

Invasive Method ◽

Frequency Power

BACKGROUND Heart rate variability (HRV) is a non-invasive method reflecting autonomic nervous system (ANS) regulations. Altered HRV is associated with adverse mental or physical health complications. ANS also has a central role in physiological adaption during pregnancy causing normal changes in HRV. OBJECTIVE Assessing trends in heart rate (HR) and HRV parameters as a non-invasive method for remote maternal health monitoring during pregnancy and three months postpartum. METHODS Fifty-eight pregnant women were monitored using an Internet-of-Things (IoT)-based remote monitoring system during pregnancy and 3-months postpartum. Pregnant women were asked to continuously wear Gear sport smartwatch to monitor their HR and HRV. In addition, a cross-platform mobile application was utilized for collecting pregnancy-related information. The trends of HR and HRV parameters were extracted using reliable data. We also analyzed the trends of normalized HRV parameters based on HR to remove the effect of HR changes on HRV trends. Finally, we exploited hierarchical linear mixed models to analyze the trends of HR, HRV, and normalized HRV parameters. RESULTS HR increased significantly during the second trimester (P<.001) and decreased significantly during the third trimester (P<.01). Time-domain HRV parameters, average normal interbeat intervals (AVNN), standard deviation of normal interbeat intervals (SDNN), root mean square of the successive difference of normal interbeat intervals (RMSSD), normalized SDNN (nSDNN), and normalized RMSSD (nRMSSD) decreased significantly during the second trimester (P<.001) then increased significantly during the third trimester (P<.01). Some of the frequency domain parameters, low-frequency power (LF), high-frequency power (HF), and normalized HF (nHF) decreased significantly during the second trimester (P<.01), and HF increased significantly during the third trimester (P<.01). In the postpartum period, nRMSSD decreased (P<.05), and the LF to HF ratio (LF/HF) increased significantly (P<.01). CONCLUSIONS Our study showed that HR increased and HRV parameters decreased as the pregnancy proceeded, and the values returned to normal after the delivery. Moreover, our results show that HR started to decrease while time-domain HRV parameters and HF started to increase during the third trimester. Our results also demonstrate the possibility of continuous HRV monitoring in everyday life settings.

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Alteration in myocardial oxygen balance during exercise after beta-adrenergic blockade in dogs

Journal of Applied Physiology ◽

10.1152/jappl.1980.49.1.28 ◽

1980 ◽

Vol 49 (1) ◽

pp. 28-33 ◽

Cited By ~ 30

Author(s):

G. R. Heyndrickx ◽

J. L. Pannier ◽

P. Muylaert ◽

C. Mabilde ◽

I. Leusen

Keyword(s):

Heart Rate ◽

Blood Flow ◽

Oxygen Consumption ◽

Myocardial Blood Flow ◽

Coronary Blood Flow ◽

Coronary Sinus ◽

Myocardial Oxygen Consumption ◽

Left Ventricular ◽

Adrenergic Blockade ◽

Oxygen Balance

The effects of beta-adrenergic blockade upon myocardial blood flow and oxygen balance during exercise were evaluated in eight conscious dogs, instrumented for chronic measurements of coronary blood flow, left ventricular pressure, aortic blood pressure, heart rate, and sampling of arterial and coronary sinus venous blood. The administration of propranolol (1.5 mg/kg iv) produced a decrease in heart rate, peak left ventricular (LV) dP/dt, LV (dP/dt/P, and an increase in LV end-diastolic pressure during exercise. Mean coronary blood flow and myocardial oxygen consumption were lower after propranolol than at the same exercise intensity in control conditions. The oxygen delivery-to-oxygen consumption ratio and the coronary sinus oxygen content were also significantly lower. It is concluded that the relationship between myocardial oxygen supply and demand is modified during exercise after propranolol, so that a given level of myocardial oxygen consumption is achieved with a proportionally lower myocardial blood flow and a higher oxygen extraction.

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Abstract P225: Non-invasive Measurement of Renal Blood Flow (RBF) in Different Rat Models by Magnetic Resonance Imaging (MRI)

Hypertension ◽

10.1161/hyp.70.suppl_1.p225 ◽

2017 ◽

Vol 70 (suppl_1) ◽

Author(s):

Cesar A Romero ◽

Robert Knight ◽

Glauber Cabral ◽

Oscar A Carretero

Keyword(s):

Blood Flow ◽

Sham Group ◽

Motion Artifacts ◽

Arterial Stenosis ◽

7 Tesla ◽

Hypertensive Rats ◽

Rat Models ◽

Non Invasive ◽

Sd Rats ◽

Invasive Method

Quantitative measure of RBF provides important information regarding renal physiology and pathology, in different animal’s models. Arterial Spin Labelling-MRI (ASL-MRI) is a non-invasive method to measure blood flow without exogenous contrast media, using arterial water protons labeled by radiofrequency as an endogenous tracer. However, the low signal/noise radio, and the motion artifacts are a challenge for the acquisition of RBF in small animals. Our objective is evaluated the feasibility and reproducibility of the RBF measure by ASL-MRI in different hypertensive rats models. ASL-MRI images were obtained in Sprague-Dawley (SD) rats (200-300g) under inhalation anesthesia using a 7 Tesla Varian MRI system with a spin echo imaging sequence. After 4 days the MRI studies was repeated to evaluate reproducibility, using paired sample T-test and the test-retest reliability (TR) equation. RBF was also measured in in Dahl SS rats on regular chow and spontaneous hypertensive rats (SHR). Additionally we measure the RBF in a set of animals under unilateral nephrectomy (UNx) and renal arterial stenosis (RS) before and after the surgery. Table 1 shows the mean cortical RBF in different rat strains and models. Re-test analysis showed no relevant differences, being the means of differences 9.4±35 ml/min/100g tissue (p=0.58) in SD rats. The TR was 92.4±6%. UNx increase the RBF in 69.1% in comparison with sham group. (p<0.01). After the RS the blood pressure increased and the RBF decrease 56% (p<0.01) in comparison with sham group. ASL-MRI performed with navigator correction and respiratory gating is a feasible and reproducible non-invasive method to measure RBF in several rat models.

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