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

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How are isovolumetric contraction and afterload related in the cardiac cycle?

In the cardiac cycle isovolumetric contraction occurs and causes a pressure gradient. The "afterload" is the pressure exerted on the ventricle from the artery. Is the afterload the cause of ...
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19 views

Determination of Ageing by ECG inclusions/exclusions?

I am studying ageing and considering ECG signal because of its high sensitivity in theory (escardio). Some factors Sensitivity Gender Medical treatment ... Benchmark: RTG dental + wrist ...
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55 views

Why do changes in preload not cause changes in end systolic pressure?

I am trying to understand why changes in preload do not cause concomitant changes in end systolic pressure. If you have preload enhancement than this should lead to an increase in cardiac ...
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11 views

ECG Calibration by Infusion Pump?

I am trying to understand how to calibrate 5-lead ECG device with an infusion pump before the human calibration as described here. The system uses 5 electrodes (RA, RL, LA, LL and Chest). The monitor ...
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68 views

Is blood pressure in the aorta and brachial artery the same or different?

Does the blood pressure at the root of aorta equal the blood pressure in the brachial artery? I've heard it does, but it doesn't quite seem to make sense as I'd think the blood pressure would be ...
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8 views

What is the realationship between arterial pressure and stroke volume

Frank-Starling Law says , When keep const Pvp (pulmonary venous pressure) and T ( heart period) and we increase Psa(aortic pressure or arterial pressure), Vd(end-diastolic volume) and Vr(residual ...
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149 views

How does sepsis affect heart function?

I have intuition that sepsis with infection can cause: spastic functioning of heart during systole heart working spontaneously in snatches during systole atrial fibrillation first contraction of ...
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70 views
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15 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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4k views

How do inward rectifier potassium channels work in the heart?

Apparently in cardiomyocytes, there is an inward rectifying potassium channel that operates during phase 4 of the cardiomyocyte action potential. I have heard that despite this potassium channel ...
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125 views

Cancer in myogenic heart cells? [duplicate]

Why cancer does not occur in myogenic heart cells? Is there any special ability in heart cells to resist cancer ?
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65 views

Persistent HPV and CVD in Women?

Cardiovascular disease is the number one morbidity factor of women. I am studying the relationship between persistent HPV infection and CVD (Cardiovascular Disease) in inadequate immune responses. ...
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5k views

Why is defibrillation in asystole (“flat line”) useless?

In most popular medical dramas, when a patient has a cardiac arrest and "flatlines" the doctors many times use a defibrillator to "shock the heart back into rhythm'. I know that actually, the proper ...
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9 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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30 views

How are cardiac cells stimulated by an action potential?

Why, and how, does the action potential of one cell in the heart stimulate an action potential in the next cell? I'm interested in an answer with citation.
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21 views

What does the term pre potential mean in the pacemaker cells of the heart?

I recently read about the concept of the pacemaker potential in the heart . In this what does the term pre potential refer to ? Is it the same as the pacemaker potential. This is because one of the ...
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28 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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705 views

How long do the periods of systole and diastole last?

The background to this is i'm doing some work using ECGs for an animation of the heart and i'm having trouble defining the end points of these periods, particularly diastole. Currently, the only ...
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5 views

How much potential from heart reaches the chest

I learn about the ECG waveform of heart potential.How much voltage will actually reach our skin which is developed in the heart(from Sinoatrial node).What will be the approximate voltage range when it ...
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311 views

How can heart disease cause dizziness after eating?

I have been reading several articles explaining dizziness after eating (see here and here), and both articles gloss over something that I found pretty remarkable. Both articles claim that "heart ...
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2answers
5k views

Why there is a very high drop in pressure from arteries to arterioles?

Laplace law explains why the pressure is the same in aorta and arteries (100). I am thinking why there is so big drop in pressure when going from arteries to arterioles (40-60). Why there is a great ...
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47 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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60 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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111 views

Normal ECG/EKG Measurement?

I'm getting started using ECG using a 3 lead system by iWorx. I have place the leads on my two wrists and the ground on my ankle and have recorded some data into the provided LabScribe 3 software ...
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53 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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448 views

Bernoulli’s Principle in the Cardiovascular System

Below are graphs which illustrate the cross-sectional area, velocity, and fluid pressure through each vascular segment of the cardiovascular system. It makes sense that velocity and cross-sectional ...
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135 views

Explanation of ECG in MI using an electrostatic model

I found a paper presenting an electrostatic model to explain the ECG recorded in various leads. This model essentially calls for considering the depolarization wavefront to be the major contributing ...
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35 views

Physiology of tricuspid and bicuspid(mitral) valves

The tricuspid and bicuspid valves are atrioventricular valves. Both are valves that prevent backflow of blood pumped from the atria to the ventricles. However, the former has 3 "flaps" while the ...
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147 views

Does our heart stop when we sneeze?

Is it fact or myth that our heart stops beating for moments when we sneeze? If it is fact, what drives the heart to start beating again?
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24 views

Any databases with AAMI ECG and ECHO?

There is no AAMI 12-lead ECG databases available online. All of them have problems. I and my friends finally finalised our tests with St Petersburg. It is not AAMI. So the next step is to search ...
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83 views

Can systemic intravascular thrombosis cause brain infarction?

I wonder if the thrombus can pass through the brain-blood barrier because I think small molecules like O2, CO2 and ethanol can pass it. Probably, in some diseases where the permeability of the barrier ...
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114 views

How does amiodarone act as an alpha and beta blocker?

Amiodarone is potassium channel blocker but also voltage-gated Na+ channel blocker according to Pubchem. However, upon reading my notes I discovered Amiodarone blocks potassium channels and block ...
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16 views

What does this sentence about angina mean?

I do not understand this sentence Angina can be treated ambulatory (in out-patient) in stable angina. I think ambulatory refers to ambulatory ECG monitoring. So I understand this that you can ...
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219 views

Why is Electrical Cardioversion contraindicated in AF and Digitalis Poisoning?

I am thinking why electrical cardioversion is contraindicated in atrial fibrillation with digitalis toxicity/poisoning. Cardiac digitalis is also called digoxin and cardiac glycoside. It is ...
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31 views

Is missing Q wave characteristic for Wolff-Parkinson-White Syndrome?

No my study books says about that no Q waves in WPW syndrome. They are about wide QRS complex often however. I heard today that the characteristic property of WPW is often a missing Q wave, like here ...
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416 views

How is the blood volume of a living organism measured without killing it?

How is the blood-volume of an organism measured without killing it? Note:The blood-volume of an organism is defined as the total volume of blood present inside that organism.
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53 views

Is PTB ECG Diagnostic Database AAMI standard?

The PTB database can be found here. There has been only one publication about the database in the recent 15 years which list challenges in the database. You can review the ECGs (electrocardiogram) ...
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68 views

Calling for Free Online Data for Paediatric ECG?

I need free online data about heart murmurs to study these: heart murmur frequency , S2 heart sound frequency and its split, murmur timing, and duration, murmur intensity, S3 sound presence and ...
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196 views

To get Standard ECG from PhysioNet?

I am trying to get standard ECG by using PhysioNet's ATM with parameters but I get It should be something like How can you get complete standard 12-lead ECG out of Physionet database?
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9k views

How does sodium in one's diet affect blood pressure?

Due to high blood pressure, my doctor has recommended I go on a low-sodium diet. So, that got me wondering what it is about sodium that drives this recommendation? What does sodium do to a body ...
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1answer
86 views

How can a heart of human work if one of its valve is not working?

Yesterday I went to a hospital and heard a doctor say that one of the heart valves of a patient is not working. However, the patient was still alive and was healthy; the patient could walk and talk ...
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133 views

Why can we control our breath rate but not our heart rate? [closed]

Even though we cannot survive for more than few minutes if we stop breathing or if our heart stops, why is it so that our heart beat is controlled involuntarily while breathing can be voluntarily ...
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139 views

Similarity between a heart attack and a spasm

When someone is having a heart attack, could it be considered , in some situations, a spasm? Below, I have written how I believe the process may work. The heart is basically a muscle working ...
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132 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 ...
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36 views

Cardiology: What are the cause and effects of sympathetic stimulation to the heart

When fight or flight response is triggered, the sympathetic stimulation causes an increase in the muscle tension throughout the body and this increases the venous return to the heart. What is the ...
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1answer
59 views

What is the insight of Frank Starling law of the heart?

The Frank Starling law appears to be a trivial observation: stroke volume is directly related to the end diastolic volume In everyday language, as more blood fills the heart, the heart pumps more ...
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31 views

What causes a small bump in the arterial pressure plot?

In my book there is a plot of the arterial pressure against time. From the plot, during heart contraction, there is greater pressure on the artery and during heart relaxation, there is lower amount ...
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228 views

Is the amount of blood that flows through every vein and artery per minute really a constant?

I was listening lectures from Mark Saltzman via Open Yale Courses. Now, if I did not understand him wrong, he said that the amount of blood that travels through every vein and artery in our bodies per ...
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108 views

Is hands-only CPR as effective as traditional CPR?

Is hands-only CPR as effective as traditional CPR ? Wouldn't 30 chest compressions + 2 rescue breaths be more effective if the person doesn't have a pulse AND not breathing? From my understanding ...
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298 views

Why do humans need a heart? [closed]

When I looked up the function of the heart, it says the heart pumps blood throughout the body. But the blood is already throughout the body, as it is recycled back to the heart. It is a chick-egg ...