The Heart, Myocardial Cell In Disease

As we began our series of discussion on how the cell can be analyzed to determine disease, we start with the Heart, Myocardial Cell, the principle functional unit of the heart organ.

Click on the image below regarding heart and myocardial cell physiology and pathophysiology.

Heart, Myocardial Cell Physiology; For Every P-wave, a QRS complex should follow; P wave to P-wave are spaced apart by approximately 1.2 to 2.0 seconds during a sinus rhythm.The Electrical System of the HEART; A 12-Lead EKG allows monitoring various walls of the heart to determine which part of the heart muscle, i.e. lateral, anterior, posterior, or septal, that may be damaged due to low or blocked blood supply to the heart muscle cell, or other abnormalityFLOW of Blood Through HEART; Deoxygenated blood comes from the upper and lower parts of the body through the vena caval system; then travels through the right heart, passing through the pulmonary arteries to the lung, and is then returned back as Oxygenated Blood to the left heart via the pulmonary veins, and finally exits the heart through the aortic valve to the rest of the the body.  This pumping cycle is repeated continuously throughout life. Chambers and Valves of the HEART; The closing of the valves gives the heart sounds that are heard during auscultation with stethoscope; The first heart sound (S1) is closing of the Atrial Valves (Tricuspid valve, and Bicuspid or Mitral Valve); and the closing of the semilunar valves (Pulmonary Valve and Aortic Valve) gives the S2 sound.  Any sound between or before those two sounds, such as S3, S4, heart murmur, etc, are abnormal HEART SOUNDS. The valves and closed chambers allow for blood to FLOW in a one direction, with dynamic pressure shifts.

Millions of Americans suffer from heart disease of one type or another. The heart, being a single organ, is one of the most important organs in the human organ systems. The principle function of the heart is to pump blood throughout the circulatory system, creating a positive dynamic mechanical pressure for cells to exchange gaseous substances, like oxygen and carbon dioxide among other, as well as to exchange nutrients, other chemical substances, and cellular waste.  In order for the heart to pump blood throughout the human circulation, it requires a dynamic muscular activity to generate a certain degree of pressure.  Without ceasing, the heart keeps a steady beat, of about 70 beats per minute depending on certain physiological conditions to generate this pressure. A series of electrical pacing, typically under the influence of an internal based electrical nodal system (sinus atrial node, AV node; Bundle of His, Right and Left Bundle Branch, and Purkinje fibers) along with the neural and endocrine systems, create a constant influx and out flux of electrical ions, starting from the atrium, moving to septum, and eventually ventricular myocardium through a sinus rhythm.

Heart Disease can essentially be divided into FOUR main categories: 1) Congenital,where the heart anatomy has abnormal structure that comes about during the fetal stage of human development, such abnormal structural diseases of the heart include abnormal heart valves, septal defects, etc; 2) Electrical, where the rhythm of the heart is dysfunctional due to genetics or other chemically/structurally induced disruption in the electrical flow through the heart; 3)  Coronary, where the blood vessels that supply the heart proper are compromised due in part principally to atherosclerotic plaques or blood clots; and 4) Myocardial, where the muscle of the heart is dysfunctional due to dying heart muscle cells (Myocardial infarction/Acute Heart attack) secondary to lack of oxygen or chemical toxicity,pathogens, cellular infiltrations, inflammation, hypertrophic or hypotrophic heart muscle cell, or scar tissue formation, or abnormal fatty tissue infiltration, for example. The main type of heart disease for adults in the USA which causes high morbidity and mortality, is principally in the myocardium, which is comprised of cardiac type muscle cells. If the heart muscle cell is developmentally, physiologically and structurally sound, then myocardial cells will function appropriately. (For the sake of brevity, the specific nature of how the cardiac muscle cell respond to this influx and out flux of ions, ie. the biochemical nature of cardiac muscle cell contraction is not discussed.  But suffice to say, if genetically sound, this process takes place without disruption.)  The unique electrical system of the heart and the coronary vessels are two components that keep the myocardial cell functioning appropriately.

Screening Exams that patients should know about when determining if their heart is functioning appropriately:

We recommend the following:

1) Patients who are forty (40) years of age or older, should at least have a baseline 12-LEAD, electrocardiogram (EKG) performed to determine if their heart rhythm is appropriate or if there is ischemic heart disease, S-T segment elevation (low flow of blood through coronary vessels, Coronary Artery Disease-CAD), or if there are signs of previous or active heart muscle damage, S-T segment depression,Q-wave, i.e. heart attack/Myocardial infarction, or myocardial hypertrophy from high blood pressure for instance, which would be demonstrated by large, SPIKED, QRS complex.

2)  Patients who have a personal and/or family history of early heart disease, ie heart disease before the age of forty (40) should have baseline 12-LEAD, EKG and other screening exams, including genotyping for genetic risks, done sooner and on a routine basis

3) All adults regardless of age, should be familiar with certain risk factors that place persons at risk of heart disease.  Among others, they include:

a) Male gender at any age, or female gender after age fifty (50)

b) History of tobacco use, or alcohol use, illicit drugs, chemotherapy, etc

c) Diabetes

d) High blood pressure

e) Obesity

f) High Cholesterol

g) Sedentary life-style

h) Clinical or Sub-clinical Hyperthyroidism,Low-TSH hormone (over active thyroid gland) in Female Gender

4) Anyone, REGARDLESS OF AGE,  with symptoms related to chest pain, shortness of breath, dizziness, palpitations, fatigue,fainting, obstructive sleep apnea, etc, should immediately seek the advice of a health care provider for further appropriate diagnostic work-up (including EKG, certain types of laboratory tests, stress tests, Echocardiogram (ECHO), Holter monitor, SLEEP STUDIES while monitoring electrical rhythm of heart, or other heart/vascular scans as appropriate), treatment, and/or management.


You only have ONE heart, and typically ONE shot, during life, to protect it!!


MDC-Atlanta remains committed to keeping patients informed for better quality health care!