Human Heart

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Human Heart ECG

HUMAN HEART

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INDEX

• HUMAN HEART ( introduction )
• PARTS OF HEART
• HOW HEART FUNCTIONS
• ECG
• HEART DISODERS
• POWER PACK

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HUMAN HEART

• Heart is hollow muscular organ that receives
  blood from the veins and propels it into and
  through the arteries.
• It is situated behind the lower part of the
  breastbone, extending more to the left of the
  midline than to the right.
• It is roughly conical in shape, with the base
  directed upwards, to the right, and slightly
  backwards the apex touches the chest wall
  between the fifth and sixth ribs.
• The heart is held in place principally by its
  attachment to the great arteries and veins, and
  by its confinement in the pericardium, a
  double-walled sac with one layer enveloping the
  heart and the other attached to the breastbone,
  the diaphragm, and the membranes of the thorax.

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HOW HEART BEATS

• Human heart is a myogenic as it generated its own
  impulse.
• Heart has 4 chambers to prevent mixing of
  oxygenated blood from deoxygenated blood.
• O2 rich blood from the lungs comes to left atrium
  , left atrium relaxes when it is collecting this
  blood . It then contracts and pushes all blood to
  left ventrilcle when it relaxes then it contracts
  to pump out blood to body .
• De-oxygenated blood comes from the body to the
  right artium of heart as it expands , then right
  artium contracts pumps blood to right ventricle
  as it relaxes then it contracts to pump out blood
  to lungs for oxidation of blood.

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• The right side of the heart is to collect
  de-oxygenated blood, in the right atrium, from
  the body (via superior and inferior vena cavae)
  and pump it, via the right ventricle, into the
  lungs (pulmonary circulation) so that carbon
  dioxide can be dropped off and oxygen picked up
  (gas exchange).
• This happens through the passive process of
  diffusion. The left side (see left hear) collects
  oxygenated blood from the lungs into the left
  atrium. From the left atrium the blood moves to
  the left ventricle which pumps it out to the body
  (via the aorta).
• Starting in the right atrium, the blood flows
  through the tricuspid valve to the right
  ventricle. Here, it is pumped out the pulmonary
  semilunar valve and travels through the pulmonary
  artery to the lungs. From there, blood flows back
  through the pulmonary vein to the left atrium. It
  then travels through the mitral valve to the left
  ventricle, from where it is pumped through the
  aortic semilunar valve to the aorta.
• The aorta forks and the blood is divided between
  major arteries which supply the upper and lower
  body. The blood travels in the arteries to the
  smaller arterioles and then, finally, to the tiny
  capillaries which feed each cell. The
  (relatively) deoxygenated blood then travels to
  the venules, which coalesce into veins, then to
  the inferior and superior venae cavae and finally
  back to the right atrium where the process began.

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ELECTROCARDIOGRAPHY (ECG)

• Electrocardiography (ECG or EKG) is a
  transthoracic interpretation of the electrical
  activity of the heart over time captured and
  externally recorded by skin electrodes .It is a
  noninvasive recording produced by an
  electrocardiographic device to electrical
  activity, cardio, Greek for heart, and graph, a
  Greek root meaning "to write".
• display indicates the overall rhythm of the heart
  and weaknesses in different parts of the heart
  muscle.
• It is the best way to measure and diagnose
  abnormal rhythms of the heart ,particularly
  abnormal rhythms caused by damage to the
  conductive tissue that carries electrical
  signals, or abnormal rhythms caused by
  electrolyte imbalances.
• the ECG can identify if the heart muscle has been
  damaged in specific areas, though not all areas
  of the heart are covered. The ECG cannot reliably
  measure the pumping ability of the heart .

showing a patient connected to the 10 electrode
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INVENTION OF ECG

• Alexander Muirhead is reported to have attached
  wires to a feverish patient's wrist to obtain a
  record of the patient's heartbeat while studying
  for his Doctor of Science (in electricity) in
  1872 at St Bartholomew's Hospital.
• This activity was directly recorded and
  visualized using a Lippmann capillary
  electrometer by the British physiologist John
  Burdon Sanderson.
• The first to systematically approach the heart
  from an electrical point-of-view was Augustus
  Waller, working in St Mary's Hospitalin
  Paddington, London
• An initial breakthrough came when Willem
  Einthoven working in Leiden, The Netherlands,
  used the string galvanometer that he invented in
  1903.
• This device was much more sensitive than both the
  capillary electrometer that Waller used and the
  string galvanometer that had been invented
  separately in 1897 by the French engineer Clément
  Ader.
• He was awarded the Nobel Prize in Medicine for
  his discovery.

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ECG ( graph paper )

• Timed interpretation of an ECG was once incumbent
  to a stylus and paper speed. Computational
  analysis now allows considerable study of heart
  rate variability.
• A typical electrocardiograph runs at a paper
  speed of 25 mm/s, although faster paper speeds
  are occasionally used. Each small block of ECG
  paper is 1 mm2.
• At a paper speed of 25 mm/s, one small block of
  ECG paper translates into 40 ms. Five small
  blocks make up one large block, which translates
  into 200 ms.
• There are five large blocks per second. A
  diagnostic quality 12 lead ECG is calibrated at
  10 m/V, so 1 mm translates into 0.1 mV.
• A calibration signal should be included with
  every record. A standard signal of 1 mV must move
  the stylus vertically 1 cm, that is two large
  squares on ECG paper.

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ECG ( graph paper )
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PLACEMENT OF LEADS
Electrode label Electrode placement
RA On the right arm, avoiding bony prominences.
LA In the same location that RA was placed, but on the left arm this time.
RL On the right leg, avoiding bony prominences.
LL In the same location that RL was placed, but on the left leg this time.
V1 In the fourth intercostal space (between ribs 4 5) just to the right of the sternum (breastbone).
V2 In the fourth intercostal space (between ribs 4 5) just to the left of the sternum.
V3 Between leads V2 and V4.
V4 In the fifth intercostal space (between ribs 5 6) in the mid-clavicular line (the imaginary line that extends down from the midpoint of the clavicle (collarbone).
V5 Horizontally even with V4, but in the anterior axillary line. (The anterior axillary line is the imaginary line that runs down from the point midway between the middle of the clavicle and the lateral end of the clavicle the lateral end of the collarbone is the end closer to the arm.)
V6 Horizontally even with V4 and V5 in the midaxillary line. (The midaxillary line is the imaginary line that extends down from the middle of the patient's armpit.)
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PLACEMENT OF LEADS IN BODY FIGURE
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Waves and intervals

• A typical ECG tracing of the cardiac cycle
  (heartbeat) consists of a P wave, a QRS complex,
  a T wave, and a U wave which is normally visible
  in 50 to 75 of ECGs.
• The baseline voltage of the electrocardiogram is
  known as the isoelectric line.
• Typically the isoelectric line is measured as the
  portion of the tracing following the T wave and
  preceding the next P wave.

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Feature Description Duration
P During normal atrial depolarization, the main electrical vector is directed from the SA node towards the AV node, and spreads from the right atrium to the left atrium. This turns into the P wave on the ECG. 80ms
PR The PR segment connects the P wave and the QRS complex. This coincides with the electrical conduction from the AV node to the bundle of His to the bundle branches and then to the Purkinje Fibers. This electrical activity does not produce a contraction directly and is merely traveling down towards the ventricles and this shows up flat on the ECG. 50 to 120ms
QRS The QRS complex is a recording of a single heartbeat on the ECG that corresponds to the depolarization of the right and left ventricles. 70 to 110ms
ST The ST segment connects the QRS complex and the T wave. 80 to 120ms
T The T wave represents the repolarization (or recovery) of the ventricles. The interval from the beginning of the QRS complex to the apex of the T wave is referred to as the absolute refractory period. The last half of the T wave is referred to as the relative refractory period (or vulnerable period). 160ms
PR The PR interval is measured from the beginning of the P wave to the beginning of the QRS complex. 120 to 200ms
ST ST interval is measured from the J point to the end of the T wave. 320ms
QT The QT interval is measured from the beginning of the QRS complex to the end of the T wave. 300 to 430ms

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Future applications of ECG

• In the future, researchers hope to simplify the
  ECG to a larger encyclopedic audience. Technology
  now allows deployment of temporary and permanent
  cardiac electrodes in a plurality of anatomic
  positions capable of novel ECGs unimpeded by the
  skin or thoracic cage.
• ECGs can be as variable as fingerprints to a
  trained observer. Patterns may be appreciated and
  computational analysis may illuminate the process
  of heterogeneity detection and to augment the
  clinical evidence supporting the validity of ECG
  heterogeneity as a predictor of arrhythmia.
• The electrocardiogram is fundamentally an
  interpretative entity but allows interventional
  measures, see Interventional Cardiology. Someday
  soon, implantable devices may be programmed to
  measure and track heterogeneity. These devices
  could potentially help ward off arrhythmias by
  stimulating nerves such as the vagus nerve, by
  delivering drugs such as beta-blockers, and if
  necessary, by defibrillating the heart.

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HEART DISORDERS

• HYPERTENSION ( high bp )
• the blood pressure more than normal (120/80
  mmhg) is called hypertension. high blood pressure
  affects the vital organs like brain and kidney.
• ANGINA (angina pectoris )
• A symptom of acute chest pain appears when
  not enough oxygen is reaching the heart muscle .
  It is common among the middle-age and elderly
  peoples . It occurs due to the conditions that
  effect the blood flow
• HEART FAILURE
• The state of heart when it is not pumping
  blood efficiently enough to meet the needs of the
  body . The person suffering from this disease
  has reduced exercise capacity.
• CORONARY ARTERY DISEASE ( CAD )
• CAD arteries undergo artherosclerosis .
  There is deposition of calcium , fats , and
  fibrous tissue which results in narrowing of the
  arterial lumen .The defect can be treated through
  angioplasty , stent and bypass surgery.

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POWER PACKS
The human heart is about the size of a closed
fist.
The average human heart, beating at 72 beats per
minute, will beat approximately 2.5 billion times
during an average 66 year lifespan.
ANATOMY OF HEART

• MORPHOLOGICAL TYPES OF HEART IN
  ORGANISMS
• CHAMBERD - eg , vertebrate and some
  noncephalopod molluscs .
• AMPULLAR - eg, crustaceon , insects and
  cephalopod .
• TUBULLAR - eg , many arthropods .
• PULSATING - eg , annelids, amphioxus ( a typical
  heart is absent ) .
• LYMPH HEART- eg , two pairs present in frog .

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THE END