Cardio Vascular System Pathological YouTube Lecture Handout

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Pathological Arrhythmias/Tachyarrhythmias

Caused by:

Ectopic Focus

Extra systole or premature beat. If discharge is occasional.

Can be:

Atrial Extrasystole

Vevtricular Extrasystole

Cardiac Arrhythmia

Caused by

  • Ectopic focus discharging repetitively & rate is higher than SAN
  • Circus movement

Ectopic Foci

Illustration: Ectopic Foci

Circus Movement

1. Wave of excitation continue to travel indefinitely in myocardium

2. Retrograde conduction due to transient block in bundle of HIS

3. Wolff-Parkinson-White Syndrome

Circus Movement

Illustration: Circus Movement
Illustration: Circus Movement
Illustration: Circus Movement

Atrial Arrhythmias

Following

  • Atrial extrasystole – atrial premature cont. are frequently present in healthy persons
  • Paraoxysmal atrial Tachycardia
  • Atrial flutter
  • Atrial fibrillation
Illustration: Atrial Arrhythmias

Pulse Deficit

  • Definition - A deficit of pulse in relation to heart rate is called pulse deficit.
  • Causes:
    • Premature contraction
    • Atrial fibrillation

Premature Contraction

  • During premature contraction, heart contracts ahead of time & if ventricles are not filled properly stroke volume decreases & in such cond. pulse wave passing to periphery may be so weak that it is not felt at the radial artery.

Atrial Fibrillation

  • Irregular adequate filling of ventricles results in pulse deficit

Atrial Flutter

Illustration: Atrial Flutter

Atrial Fibrillation

Illustration: Atrial Fibrillation

Ventricular Arrhythmias

  • Ventricular tachycardia – Broad, bizarre QRS complex
  • Ventricular Flutter, Ventricular Fibrillation – Clinically ventricular asystole

Ventricular Tachycardia

Illustration: Ventricular Tachycardia

Ventricular Fibrillation

Illustration: Ventricular Fibrillation
Illustration: Ventricular Fibrillation

Fibrillatory waves

Illustration: Ventricular Fibrillation

Paroxysmal Tachycardia

  • Is a bout of tachycardia which begins & ends suddenly (paroxysm = a sudden outburst)
  • A bout can last for several minutes

Types – Depending on the Site of Ectopic Focus

1. Paroxysmal Atrial (atrial rate = 160 - 220/min) Tachycardia

2. Atrioventricular junctional Tachycardia (atrial rate = 120 - 200/min)

3. Ventricular Tachycardia (ventricular rate = 140 - 220/min)

Paroxysmal supraventricular Tachycardia includes Atrial & Junctional Tachycardia

Myocardial Ischemia

  • Myocardial ischaemia -Is interruption in blood supply of heart.
  • Irreversible changes & death of muscle cells
Illustration: Myocardial Ischemia

ECG Changes in MI

Table of ECG Changes in MITable of ECG Changes in MI
Defect in infarcted CellsEcg changes in over lying leads
1. Rapid RepolarizationST seg elevation
2. Decreased RMPST seg elevation
3. Delayed DepolarizationST seg elevation

ECG Findings in MI

Findings in ant. Infarct:

Table of ECG Findings in MI Table of ECG Findings in MI
TimeChangesLeads
Hrs aft. Inf.ST ele.

ST dep.

I, aVL &

II, III& aVF

Hrs to daysQ waveI, aVL, &
WeeksQ wave & QS complex ST seg. becomes isoelectric T wave invertedpersists
Late yearsQS complex persists,T wave normal
Illustration: ECG Findings in MI

Contiguous Leads

Illustration: Contiguous Leads

ECG – Ionic Changes

Hyperkalemia (↑K+ ) -Dangerous & lethal

  • Tall & peaked T wave
  • Prolongation of QRS complex
  • Paralysis of atria
  • Vent. Arrhythmias
  • RMP decreases
Illustration: ECG – Ionic Changes

ECG in Hypokalemia

  • Hypokalemia (↓K+ ) -less dangerous
  • PR interval prolonged
  • U wave prominent
  • T wave invertion in chest leads
Illustration: ECG in Hypokalemia

Hypercalcemia

Hypercalcemia (↑Ca++ )

  • Enhances myocardial contractility
  • Heart stops in systole

(Clinically this level is not reached)

  • Hypercalcemia (↓Ca++ )
  • Seg. prolonged

Effect of Sodium

  • Sodium level has little effect
  • ↓Na+ … Low voltage ECG

ECG: Uses

  • Detection of HR
  • Ectopic focus
  • Heart block
  • MI
  • Axis deviation
  • Electrolyte imbalance
  • Research

ECG Limitation

  • False negative
  • False positive

HIS Electrogram

Illustration: HIS Electrogram

Cardiac Cycle

Includes various changes in heart from beat to beat

  • Mechanical changes/cardio dynamics
  • Electrical changes

Events During Cardiac Cycle

Atria & ven. are two separate units connected by conducting tissue only Main events are

  • Atrial contraction
  • Atrial relaxation
  • Ventricular contraction
  • Ventricular relaxation

Atrial Cycle

  • Total duration of one cycle is 0.8 sec (HR 75/mit)
  • Atrial cycle
    • Atrial systole … 0.1 sec
    • Atrial diastole … 0.7 sec

Ventricular Diastole

  • Diastole … 0.5 sec
  • Protodiastolic phase … 0.04 sec
    • Isovolumic relaxation … 0.08 sec
    • First rapid filling … 0.10 sec
    • Slow filling/diastasis … 0.18 sec
    • Last rapid filling … 0.10 sec

Changes During Cardiac Cycle

  • Mechanical changes
  • Valvular changes
  • Pressure changes in
    • Atria
    • Ventricles &
    • Aorta
  • Volume changes in ventricles
Illustration: Changes During Cardiac Cycle
Illustration: Changes During Cardiac Cycle

CARDIAC CYCLE

Illustration: CARDIAC CYCLE

CARDIAC CYCLE

Illustration: CARDIAC CYCLE

CARDIAC CYCLE

Illustration: CARDIAC CYCLE

CARDIAC CYCLE

Illustration: CARDIAC CYCLE

CARDIAC CYCLE

Illustration: CARDIAC CYCLE

CARDIAC CYCLE

Illustration: CARDIAC CYCLE

Ventricular Cycle - Systole

  • Systole … 0.3 sec
    • Isometric/isovolumic contraction- 0.05 sec
    • Rapid/maximum ejection … 0.10 sec
    • Reduced ejection … 0.15 sec

Valvular Changes

Changes are in

  • AV valve (atrioventricular)
    • Mitral (bicuspid)
    • Tricuspid
  • Semilunar valves
    • Aortic
    • Pulmonary

Heart Sounds

Heart Sounds β€” total 4 types

  • I, II, III, & IV
    • I & II heard by stethoscope
    • III & IV picked by phonocardiography
    • Period between I & II … Systolic period
    • Period between II & I … Diastolic period

I & II Heart Sounds

Illustration: I & II Heart Sounds

I H. S

First heart sound

  • Mechanism of generation:
    • Vibrations of closing valve
    • Turbulance of blood
    • Vibrations of ventricular wall

Two components Mitral & Tricuspid

Characteristics I HS

Are:

  • Prolonged & soft … Lubb
  • Duration … 0.15 sec
  • Frequency … 25 … 45 Hz

Auscultation- Best heard in Mitral & Tricuspid areas

Auscultation- I HS

  • Mitral Area (near apex beat) -Lt. V ICS
  • Slightly inside the mid clavicular line
  • Tricuspid Area -Lt V ICS near sternal border

Significance

  • Marks beginning of systole
  • Duration & intensity indicates condition of myocardium & A-V valves.
  • Proper closure of A-V valves
  • Coincides with R wave of ECG

Abnormalities of I HS

Faint Sound-

  • Weak myocardium
  • PR interval prolonged
  • Calcific mitral stenosis
  • Mitral incompetence

Intense Sound-

  • more force of contraction

Intense Sound (Loud) -

  • more force of contraction
  • Mitral stenosis
  • Short PR interval
  • Splitting of Mitral & Tricuspid by 10 to 30 ms. is normal
  • Split sound … bundle branch block.

II HS

Mechanism of generation;

  • Closure of semilunar valves
  • Oscillation of Aortic & Pulmonary walls
  • Oscillation of blood column in Aorta & Pulmonary artery

Auscultation-II HS

Characteristics: like β€˜dup’

  • Duration … 0.12 sec
  • Frequency … 50 Hz.

Auscultation – Best at Aortic & Pulmonary Areas

  • Aortic Area … Rt. II ICS near the sternum
  • Pulm. Area … Lt. II ICS near the sternum

Splitting of -II HS

  • It has two components Aortic & Pulmonary Normal splitting
  • During inspiration … 0.04 sec
  • During expiration … 0.02 sec

Signifance -II HS

  • Marks end of systole & beginning of diastole
  • Clear sound indicates perfect closure of semilunar valves & there is no (incompetence)
  • Coincides with end of T wave of ECG

Applied Aspects

  • Intensified if Aortic or pulmonary press. Is high
  • Splitting in Bundle branch block
Illustration: Applied Aspects
Illustration: Applied Aspects
Illustration: Applied Aspects

III HS

  • Mechanism- Vibrations of ventricular wall caused by rapidly entering blood
  • Characteristics- Short, soft & low pitched
    • Duration- 0.1 sec
  • Auscultation- Normally not heard with stethoscope, can be recorded
  • Appears between T & P waves of ECG

IV HS

  • Mechanism- Vibration caused by last rapid filling
  • Characteristic- Short & low pitched
  • Duration- 0.03 sec
  • Recorded by phonocardiography
  • Falls between end of P wave & onset of Q wave

Phonocardiogram

  • A microphone is applied to precordium
  • Sounds are amplified & recorded by oscillograph
  • The record is called phonocardiogram
Illustration: Phonocardiogram
Illustration: Phonocardiogram

Murmurs

Definition- are abnormal heart sounds produced during cardiac cycle

Type of murmur Abnormality

Systolic - Aortic/pulmonary Stenosis

Mitral/Tricuspid Insufficiency.

Diastolic - Aortic/Pulmonary Insufficiency. Mitral/Tricuspid Stenosis

Illustration: Murmurs

Cardiac Cycle

Illustration: Cardiac Cycle