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

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Cancer in myogenic heart cells?

Why cancer does not occur in myogenic heart cells? Is there any special ability in heart cells to resist cancer ?
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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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95 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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21 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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106 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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19 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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79 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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44 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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13 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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58 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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20 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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377 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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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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64 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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174 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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6k 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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61 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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82 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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118 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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97 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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163 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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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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35 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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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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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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65 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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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 ...
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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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Why is heart failure treated as more critical than kidney failure?

The heart pumps the blood to supply tissues and kidney always filters the blood to remove urea,extra water and etc. And all these are vital,so the kidney is as important as heart: and my question is: ...
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948 views

Arm at Heart Level when Measuring Blood Pressure

How come that one's arm has to be at heart level so that the blood pressure can be measured accurately. I've tried researching this question, but most answers to it were just "if the arm is above the ...
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148 views

How can we measure cardiac output?

I could find a way which could find it by body oxygen consumption and there is another way to measure it by injecting drugs — measuring cardiac output by the so-called “indicator dilution method,” a ...
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What's Incomplete atrioventricular heart block (AV)? [closed]

This is unclear for me and I can not understand differences between complete and incomplete atrioventricular heart block.also I want an electrocardiograph of incomplete atrioventricular heart block.
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129 views

What’s the reason for isovolumic contraction and isovolumic relaxation?

During cardiac cycle, there are two periods in which the heart volume doesn’t change, but there is a change in tension/pressure. It takes about 0.25-0.35 second to achieve this change. I searched in ...
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80 views

Biphasic T wave caused by digitalis toxicity

Digitalis is a drug that can be used during coronary insufficiency to increase the strength of cardiac muscle contraction. But when overdosages of digitalis are given, depolarization duration ...
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79 views

Why is pericardium muscle repolarizated earlier than endocardium? [closed]

I was reading about heat muscle contraction and I read: The endocardium depolarization happens earlier than pericardium , but pericarduim repolarization happens earlier, therefore the T wave in ...
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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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144 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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59 views

Heart Rate being normal when under treatment for the bends

When you surface from diving too quickly; you get "bends" - these are caused by gas bubbles forming in your lungs (especially nitrogen). This causes breathing problems if not treated since the bubbles ...
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How to measure Na/K channel activation at the membrane level?

Assume that there are two different signals occurring on the ECG - during depolarization and repolarization in the standard ECG. I was advised not to use the standard ECG in measuring the exact ...
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Speed of effective lymphatic drainage?

Lymphatic drainage occurs from many portions of the body: To venous angle: head axillary lymph nodes hands abdomen legs (I think legs' drainage goes through abdomen) The speed of the lymph ...
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Why is sarcoma more prevalent and common in right heart?

Ewing's sarcoma or Ewing sarcoma is a malignant small, round, blue cell tumor. It is a rare disease in which cancer cells are found in the bone or in soft tissue. It is more common in right heart than ...
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344 views

How does vasoconstriction/vasodilation change blood pressure?

Background: I am coming at this question from an electrical engineering background, and I feel like I am missing certain assumptions that are going into the statement found in my physiology textbook, ...
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142 views

What is the name of the condition where no pacemaker cells are active in the heart for a short-time?

Assume that the heart is beating, but no pacemaker cells are working for at least 15 seconds. This would be a very long compensatory pause if extrasystole started it. There may be some low frequent ...
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85 views

What shows how healthy someone is by their heart rate? [closed]

What shows how healthy someone is by their heart rate - how low it is at resting pulse or how low it is during exercise or how large the difference is between the resting rate and rate with load? Any ...
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2answers
119 views

Why can't we defibrillate the heart within 1 minute after ventricular fibrillation by electroshock?

We mostly can defibrillate the heart before 1 min of ventricular fibrillation by electroshock.Then we often can't do defibrillate it with electroshock. What's the reason and What's the best way to ...
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Why do the size of the phase 1 notch vary among cardiac cells?

The size of the phase 1 notch varies among cardiac cells. It is prominent in myocytes in the epicardial and midmyocardial regions of the left ventricular wall and in ventricular Purkinje fibers. ...
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52 views

Is the molecule nitric oxide responsible for healing blood vessels?

Is the molecule nitric oxide responsible for healing blood vessels? How does nitric oxide heal the blood vessels? I watched a documentary about the healing effects of nitric oxide. In the video I ...
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214 views

Why don't we see turbulence in the aorta even in normal situations?

I read about the Windkessel effect. Then I read about pulse pressure waves getting reflected from the periphery. If the pulse pressure wave is reflected during diastole and at the same time blood is ...
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What does irregular heartbeat mean in simple language?

I bought a blood pressure monitor (A&D UA-851) which has the option to measure irregular heartbeat. I do understand what 'irregular' means, but why do irregular heartbeats happen and what are ...