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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0answers
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 ...
5
votes
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 ...
5
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0answers
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 ...
4
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0answers
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 ...
3
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0answers
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 ...
3
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0answers
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 ...
3
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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
votes
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
votes
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. ...
2
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0answers
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 ...
2
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0answers
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 ...
2
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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? ...
2
votes
0answers
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 ...
2
votes
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 ...
2
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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, ...
2
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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
votes
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 ...
2
votes
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 ...
2
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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 ...
1
vote
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 ...
1
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0answers
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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0answers
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.
1
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0answers
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 ...
1
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0answers
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 ...
1
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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 ...
1
vote
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 ...
1
vote
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 ...
1
vote
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 ...
1
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0answers
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 ...
1
vote
0answers
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 ...
1
vote
0answers
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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0answers
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 ...
1
vote
0answers
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 ...
1
vote
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 ...
1
vote
0answers
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.
1
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0answers
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 ...
1
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0answers
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 ...
1
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0answers
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 (...
1
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0answers
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 ...
1
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0answers
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 ...
1
vote
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 ...
1
vote
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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0answers
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 ...
1
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0answers
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 ...
1
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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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0answers
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 ...
1
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0answers
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 ...
1
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0answers
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 ...
