Questions tagged [cardiology]

The study of the physiology and pathology of the heart and the cardiovascular system.

74 questions with no upvoted or accepted answers
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350 views

Effect of Aging on SA node's sympathetic fibers

I am trying to understand the effect of aging on the sympathetic fibers of SA node. I know that aging shifts the vagal curve to left in frequency due to aging. However, I am interested if aging has ...
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1answer
1k views

What's so special about Chassaignac tubercle?

1-How does massaging of carotid artery at chassaignac tubercle( anterior tubercle of transverse process of C6 vertebra ) can relieve the symptoms of Supraventricular Tachycardia? My attempt: I think ...
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135 views

Evolutionary explanation of the bicuspid on the left and tricuspid on the right

The left heart handles more pressure and logically it would make sens to have a valve with three leafs on the left (If I had got to choose, I'd have put three on both sides). Other than being more ...
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284 views

Understanding beat annotations of arrhythmia ECG dataset

I'm trying to understand the rhythm changes in the MIT BIH dataset. In annotations, there are 2 main types. Beat annotations and rhythm annotations. Rhythm annotations (aux_notes field) contains ...
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23 views

Why does the posterior region and the right ventricle of the heart are not well represented in standard 12 leads?

When assessing an ECG we divide our 12-lead into four main contiguous lead groups: inferior, lateral, septal, and anterior. Regions not well represented on a standard 12-lead are the posterior region ...
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951 views

Why is there a structural difference between the bicuspid and tricuspid valve?

There are three cusps in the tricuspid valve and only two in the bicuspid valve? Why is there such a structural difference? Does it have anything to do with that there is oxygenated blood on the left ...
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0answers
109 views

How do cellphones calculate heart rate?

How do cellphones calculate heart rate ? I understand that the cameras there try to count undulation in blood flow, but is the method of calculation same as that of professional SpO2 monitors ?
3
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2answers
919 views

What is the effect of persistent hypothermia on cardiac performance?

I define persistent hypothermia in this thread about the mechanisms of persistent hypothermia. The Graph of Katzung et al. in Pharmacology about Heart Failure: I am thinking which parts here are ...
2
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0answers
58 views

How can I simulate heart electrical activity in a 2D plane?

I am not a biologist/medical student, I study software engineering. But I really like when medicine and engineering hold their hands together to achieve great things. As a side/toy project, I was ...
2
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0answers
299 views

What drives max heart rate on beta blockers?

In a healthy human being, the increase in heart rate from rest to around 100 to 110 beats per minute at low intensity exercise is due to withdrawal of the parasympathetic nervous system's influence. ...
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88 views

How much do arteries expand during pulse?

Arteries expand during a pulse. The amount of expansion may differ from artery to artery. How much do arteries expand? I understand it might be a range. Inform the same. Even values specific to some ...
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206 views

Why does fetal distress (hypoxia) cause bradycardia?

In a non stress test performed in the labor room, fetal bradycardia is a danger sign indicating fetal distress (hypoxia). Why does fetal hypoxia cause bradycardia while hypoxia in adults cause ...
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0answers
22 views

Why are valves preferentially affected in endocarditis?

The inside of the heart is covered by endothelium throughout. Why are valves predisposed to endocarditis? I know it can affect other structires like the septum, chordae etc. But why the valves? ...
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116 views

Plaque rupture flow chart reading

I am having a bit of trouble interpreting flow charts given in my biology question sets. Given the following stimulus The Question is : In which of the following options does each substance play ...
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0answers
646 views

Why do earthworms have 4 hearts?

I was reading about earthworms and came to know that they have 4 hearts. Why is there a need for a 4 heart system? What advantages would it have over a 1 heart circulatory system except for pumping ...
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0answers
46 views

Neural correlates of the function of the cardiovascular system?

Are there any known neural correlates of the function of the cardiovascular system? I'm looking for research results that use standard brain imaging techniques (e.g. electroencephalography, ...
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0answers
103 views

ECG of heart transplant patients

I am studying ECGs of heart transplant patients. The difficult thing is that there is so little available data publicly. I must apply for data in my universities. It would be also great if ...
2
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0answers
383 views

To define the total Resistance of Systemic Blood Circulation

Some systems are in parallel. For instance, the resistance of lungs $R_{\text{lungs}}$. Assume here for simplicity that these parallel systems can be handled linearly. We also consider only Total ...
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0answers
58 views

If a receptor is inhibited throughout embryogenesis, could there be observable phenotypic differences in the adult?

So I read a journal article entitled "Maternal hypoxia and caffeine exposure depress fetal CV function during primary organogenesis" (Momoi, et al., 2012) and in essence the article speaks of the ...
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0answers
73 views

Can we make any judgements about sleep or readiness to sleep from a heart rate metric and/or pulse oxymetry?

I'm looking at inexpensive and un-intrusive ways to quantify the state of human body/mind . One of these is Actigraphy, which is a study of human motion over time. This can be done with an iPhone ...
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0answers
13 views

Is there a way to derive Bazett's formula to correct QT interval in ECG?

As we know that QT interval in ECG is a function of heart rate (HR) and to comment on the pathology associated with altered QT interval, we must neutralise the effect of HR. For this Bazett's formula ...
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17 views

Understanding the ECG waveform with respect to Lead Positions

I am really confused about the Representation of potential in an ECG graph. First i will ask what is on the vertical axis? (I guess it is electrical potential in millivolts) But again it changes for ...
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36 views

How much blood do we have when the heart first starts to beat?

How much blood do we have when the heart beats for the first time? It should be between the third and fourth week of embryonic life.
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28 views

Why does a stronger heart cause blood pressure go down

Intuitively, why does a stronger heart cause blood pressure to go down? The answers I've found from a cursory google search seem to indicate that it has to "work less hard" to pump the blood and that ...
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17 views

Correlation seen with low billirubin levels but not the gene that causes Gilbert's syndrome

I was reading the following study on associations between bilirubin and CAD (coronary artery disease). They looked at the bilirubin association, and the genes that cause Gilbert's syndrome, which ...
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0answers
26 views

Vasoconstriction and blood flow

The resistance in a blood vessel is equal to the pressure difference divided by the blood flow. Let us now say that a sympathomimetic causes vasoconstriction which increases the resistance. Does this ...
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0answers
31 views

Is the medium which transmits the electrical impulse through the heart different to a nerve?

According to Nerve A nerve is an enclosed, cable-like bundle of nerve fibres called axons Being an Axon An axon (from Greek ἄξων áxōn, axis), or nerve fiber, is a long, slender projection of a ...
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1answer
78 views

ECG detection using minimal number of electrodes

Disclaimer: Hello, I'm someone from an electrical engineering background, so this question may sound dumb. I wish to make a wearable ECG monitoring device for arrhythmia detection. Since the device ...
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0answers
89 views

How does alcohol interact with sympathomimetics to affect the cardiovascular system?

There is a fair amount of information on the cardiovascular effects of alcohol, and of sympathomimetics. How do they work? And how do their mechanisms interact? We know that similar pathologies ...
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187 views

How to obtain normalised ECG given ECG readings across lead 1, 2, and 3?

I saw this youtube video on ECG readings and cardiac dipole vector locus of the heart across the three leads. Posting screenshots from it: My question is how to obtain the graph (2nd image) from the ...
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56 views

Pain and Angina Pectoris

What causes pain in an angina pectoris? Ok, heart muscles may lack oxygen, but what is the role of pain here? Is it being beneficial? I'd like to know the physiological process of induction of pain ...
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52 views

effect of arterial vasocontriction on the pressure in arteries

if experimentally one induces smooth muscle contraction on an artery and cause it to constrict, keeping the cardiac output same and also the arteriolar resistance(total peripheral resistance) the same ...
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102 views

law of laplace and pressure developed in arteries

in arterioles the pressure depends on the impedance of the vessel(elasticity and youngs modulus) cardiac output pre arteriolar resistance what i want to ask is will the pressure also depend on law of ...
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30 views

How does heart rate change when entering N1 sleep?

I would like to know how the heart rate changes as a person enters N1 (NREM 1) sleep from a wakeful state. The focus is on entering N1, and it would be great to have time-series data to see the ...
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0answers
42 views

Do blood vessels expand during angiogenesis?

I know that there are two usual ways of creating new blood vessels: A new vessel sprouts from the wall of an old one, A wall of cells grows down the middle of a vessel, splitting it into two. I also ...
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64 views

Different number of flaps in heart valves

Can anyone tell me why the different valves of heart have different number of flaps is it in any way related to evolution of homo sapiens.
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38k views

Exsanguination Time from Damage to Major Arteries

For a game project, I need to study how much blood loss is suffered when the major arteries of the human body are severed. I believe there are medical textbooks that have collected data on blood ...
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40 views

State of voltage gated sodium channels in depolarised potentials

Case 1 We learn in Physiology that during the depolarization phase in the membrane, more sodium channels tend to open as the membrane potential increases i.e., less negative. This is a kind of ...
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70 views

How much Cardiomyocyte Move in Relation to its Neurons?

I am trying to estimate how much cardiomyocyte and its things (mitochondria) move in relation to neurons Movement of neurons (1) Movement of cardiomyocytes Movement of cardiomyocytes' mitochondrias (...
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51 views

Pathogenesis of Cardiac Atypia?

I am studying the pathogenesis of atypia in cardiac cells where the etiology is most commonly irritation or infection and where the precancerous risk depends on the context of diagnosis. This fact ...
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39 views

Membrane conductance in phase 1 of the cardiac action potential

Correct me if I am wrong, but in phase 1 of the cardiac action potential (for ventricle cells) there is flow of potassium ions due to the opening of transdent potassium channels. To me this would ...
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0answers
279 views

Reasons for strange heart rate graph following exercise (line going up and down)?

Following a 2 minute general jumping and movement exercise designed to involve the entire body, the pulse was taken every minute for ten seconds. Strangely, the graph appears to jump up and down, for ...
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0answers
34 views

How can hyperplasia occur in non-fetal hypokinesis?

I have read that the hypoplasia can occur in fetal hypertrophic cardiomyocytes. However, I am interested if this can be theoretically be possible in non-fetal cardiomyocytes which are hypokinetic. I ...
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0answers
81 views

Can bigger persons generally resist g-forces better?

I've seen a claim that bigger persons generally resist g-forces worse than smaller in an undergraduate biology book. However this claim was supported by the argument that blood has to travel a longer ...
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66 views

Public Pacemaker database online?

I am looking for any database about pacemakers with the leads atria A right ventricle VR left ventricle VL I did not find any in Physionet. Is there any anonymous data about different situations ...
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80 views

Recovering Coma patient with theoretical full knowledge of heart function

In coma, there is the medullary depression (stage of agony). Spontaneous respiration and circulation cease i.e. vasomotor center. There is no full circulatory and respiratory support. Assume you ...
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0answers
969 views

How is Calcium regulated in myocardic AP and plateau phase?

The plateau phase is maintained by influx of calcium and outflux of potassium in the second stage: My conjecture is that calcium transforms between two phases ionated phase (free calcium from i/c SR ...
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789 views

What is the nature of action potentials in autonomic nervous system?

My conjecture is that the natures of sympathetic and parasympathetic action potentials are different. My findings propose me that sympathetic action potential is little longer lasting than ...
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238 views

What are the mechanisms of disabling extrinsic control of heart?

I started this thread by thinking this question but I developed it further below What is the mechanism maintaining refractory period of pacemakers? My conjecture is that the mechanism is the ...
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83 views

Which reflex arcs work in Heart with extrasystoles?

I am researching what is triggering the extrasystoles - initial idea from this thread about Which ionic channels of Pacemakers can work in very low frequencies in extrasystole? I am interested in the ...