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
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
Atrial Arrhythmias
Following
- Atrial extrasystole β atrial premature cont. are frequently present in healthy persons
- Paraoxysmal atrial Tachycardia
- Atrial flutter
- Atrial fibrillation
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
Atrial Fibrillation
Ventricular Arrhythmias
- Ventricular tachycardia β Broad, bizarre QRS complex
- Ventricular Flutter, Ventricular Fibrillation β Clinically ventricular asystole
Ventricular Tachycardia
Ventricular Fibrillation
Fibrillatory waves
Paroxysmal Tachycardia
- Is a bout of tachycardia which begins & ends suddenly (paroxysm = a sudden outburst)
- A bout can last for several minutes
Types β 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
ECG Changes in MI
Defect in infarcted Cells | Ecg changes in over lying leads |
---|---|
1. Rapid Repolarization | ST seg elevation |
2. Decreased RMP | ST seg elevation |
3. Delayed Depolarization | ST seg elevation |
ECG Findings in MI
Findings in ant. Infarct:
Time | Changes | Leads |
---|---|---|
Hrs aft. Inf. | ST ele. ST dep. | I, aVL & II, III& aVF |
Hrs to days | Q wave | I, aVL, & |
Weeks | Q wave & QS complex ST seg. becomes isoelectric T wave inverted | persists |
Late years | QS complex persists, | T wave normal |
Contiguous Leads
ECG β Ionic Changes
Hyperkalemia (βK+ ) -Dangerous & lethal
- Tall & peaked T wave
- Prolongation of QRS complex
- Paralysis of atria
- Vent. Arrhythmias
- RMP decreases
ECG in Hypokalemia
- Hypokalemia (βK+ ) -less dangerous
- PR interval prolonged
- U wave prominent
- T wave invertion in chest leads
Hypercalcemia
Hypercalcemia (βCa++ )
- Enhances myocardial contractility
- Heart stops in systole
(Clinically this level is not reached)
- Hypercalcemia (βCa++ )
- Seg. prolonged
Effect of Sodium
- Sodium level has little effect
- βNa+ β¦ 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
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 β¦ 0.1 sec
- Atrial diastole β¦ 0.7 sec
Ventricular Diastole
- Diastole β¦ 0.5 sec
- Protodiastolic phase β¦ 0.04 sec
- Isovolumic relaxation β¦ 0.08 sec
- First rapid filling β¦ 0.10 sec
- Slow filling/diastasis β¦ 0.18 sec
- Last rapid filling β¦ 0.10 sec
Changes During Cardiac Cycle
- Mechanical changes
- Valvular changes
- Pressure changes in
- Atria
- Ventricles &
- Aorta
- Volume changes in ventricles
CARDIAC CYCLE
CARDIAC CYCLE
CARDIAC CYCLE
CARDIAC CYCLE
CARDIAC CYCLE
CARDIAC CYCLE
Ventricular Cycle - Systole
- Systole β¦ 0.3 sec
- Isometric/isovolumic contraction- 0.05 sec
- Rapid/maximum ejection β¦ 0.10 sec
- Reduced ejection β¦ 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 β¦ Systolic period
- Period between II & I β¦ Diastolic period
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 β¦ Lubb
- Duration β¦ 0.15 sec
- Frequency β¦ 25 β¦ 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 β¦ 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 βdupβ
- Duration β¦ 0.12 sec
- Frequency β¦ 50 Hz.
Auscultation β Best at Aortic & Pulmonary Areas
- Aortic Area β¦ Rt. II ICS near the sternum
- Pulm. Area β¦ Lt. II ICS near the sternum
Splitting of -II HS
- It has two components Aortic & Pulmonary Normal splitting
- During inspiration β¦ 0.04 sec
- During expiration β¦ 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
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
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