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CARDIAC PHYSIOLOGY& ANAESTHETIC CONSIDERATIONS
By- Dr. Armaan Singh
Heart
Hollow Located within the mediastinum of the thoraxDistal end extends downward to the left forming apex at the
fifth intercostal space.
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HEART STRUCTURE ANATOMICALLY ONE ORGAN FUNCTIONALLY DIVIDE INTO RT. & LT PUMPSFOUR VALVES WITH UNIDIRECTIONAL FLOW
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Pulmonaryand SystemicBloodflow
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The heart consists of three different layers
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Coronary supplyInferior Rt coronary
Anteroseptal Lt ant descening
Anteroapical Lt ant desceding( distal)
Anterolateral Circumflex
Posterior Rt coronary artery
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CARDIAC ACTION POTENTIALl
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ME
MB
RA
NE
PO
TE
NT
IAL
(m
V)
-90
0
0
12
3
4
TIME
PHASE0 = Rapid Depolarization (inward Na+ current) 1 = Overshoot2 = Plateau (inward Ca++ current)
3 = Repolarization (outward K+ current)4 = Resting Potential
Mechanical Response
PACEMAKERS (in order of their inherent rhythm)
• Sino-atrial (SA) node• Atrio-ventricular (AV) node• Bundle of His• Bundle branches• Purkinje fibers
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AtrioVentricular Node
Sinoatrial Node
Atrioventricular Bundle
Purkinje Fibers
Heart Conduction System
INITIATION & CONDUCTION OF THE CARDIAC IMPULSE
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Heart Actions• Atrial systole is when the atria contract while the ventricles
relax which is called ventricular diastole.• Thus systolic and diastolic blood pressure.• This series of contraction and relaxation is called a cardiac
cycle.
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LATE DIASTOLE
ATRIALSYSTOLE
ISOMETRIC VENTRICULARCONTRACTION
VENTRICULAR EJECTION
ISOMETRICVENTRICULARRELAXATION
EVENTS IN CARDIAC CYCLE
DIASTOLE
CARDIAC CYCLE
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Atr
ial
Syst
ole
Mitral Closes
Isov
olum
ic c
ontr
act.
Aortic opens
S1
Rap
id E
ject
ion
Red
uced
Eje
ctio
n
Isov
olum
ic R
elax
.
Aorticcloses
Rap
id V
entr
icul
arF
illi
ng
Mitralopens
S2
Red
uced
Ven
tric
ular
Fi
llin
g
Atr
ial
Syst
ole
CARDIAC OUTPUT• DEFIND AS VOLUME OF BLOOD PUMPED BY HEART/MIN• CO = SV X HR • SV IS VOLUME PUMPED PER CONTRACTION• average cardiac output would be 5L.min-1 for a human male
and 4.5L.min-1 for a female.
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CARDIAC OUTPUT AND THE FICK PRINCIPLE
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BODY O2 CONSUMPTION
250mlO2/min
PaO2
190mlO2/l blood
PvO2
140mlO2/l blood
PULMONARYARTERY
PULMONARYVEIN
CARDIAC OUTPUT=O2 CONSUMPTION (ml/min)
PaO2- PvO2
Pulmonary capillaries
Lungs
Pulse
• Pressure wave move along the artery wall which are pliable
• usually measured in beats per minute • normal range from 60 to 100 beats per minute
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Factors Influencing the Pulse• Stroke volume
• Rate of ejection
• Distensibility of peripheral arteries
• Peripheral resistance
• Pulse rate
• Pulse pressure
• Size of the vessel
• Distance from the heart
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Pulsus Parvus
• The pressure is diminished, and the pulse feels weak and small, seen in - restrictive pericardial disease, hypovolemia, mitral stenosis
• Pulsus Parvus et Tardus (weak and delayed): →Aortic Stenosis
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Bisferiens Pulse
• Increased arterial pulse with a double systolic peak. • Causes : AR
• HCM
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Bigeminal Pulse
• characterized by groups of two heartbeats close together followed by a longer pause. The second pulse is weaker than the first
• Causes: severe HF, hypovolemic shock, cardiac tamponade)
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Pulsus Alternans
arterial pulse waveform showing alternating strong and weak beats
• Causes:• Left ventricular failure • severe AR
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Pulsus Paradoxus
• Pressure drop > 20 mmHg during inspiration.• Normally, systolic arterial pressure falls 8-12 mmHg during
inspiration.• Causes:• Cardiac Tamponade• COPD, hypovolemic shock
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BLOOD PRESSURE• DEFINE AS PRESSURE OF BLOOD AGAINST THE WALL OF MAIN
ARTRIES• HIGHEST DURING SYSTOLE N LOWEST DURING DIASTOLE• MEASURED BY SPHYGMOMANOMETER @ BRACHIAL ARTERY
OF ARM
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Blood Pressure (BP): Measurements
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Figure 15-7: Measurement of arterial blood pressure
CLASSIFICATION
Category Systolic Diastolic
hypotension <90 <60
normal 90 – 119 60 - 79
prehypertesion
120 - 139 80 - 89
stage1ht 140 - 159 90 - 99
stage2ht >160 >100By- Dr. Armaan Singh
Pulse and Mean Arterial Pressures
• Pulse pressure = Systolic –Diastolic• Mean arterial pressure (MAP) = Diastolic +
1/3 pulse pressure
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EJECTION FRACTION• Ejection fraction (Ef) is the fraction of the end-diastolic
volume that is ejected with each beat• it is stroke volume (SV) divided by end-diastolic volume (EDV):
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EJECTION FRACTION• In a healthy man, the SV is approximately 70 ml and the left
ventricular EDV is 120 ml, giving an ejection fraction of 70/120, or 0.58 (58%).
• Healthy individuals typically have ejection fractions between 50% and 65%
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METHODS OF EF MEASUREMENT • CARDIAC CATHETRISATION
• RADIONUCLEOTIDE STUDIES
• ANGIOCARDIOGRAPHY
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CARDIAC INDEX
• Cardiac index (CI) is a vasodynamic parameter that relates the cardiac output to body surface area
• unit of measurement is (l/min/m2) • normal range of cardiac index is 2.6 - 4.2 L/min per square meter.
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ANAESTHETIC CONSIDERATION• Halothaane isoflurane and enflurane depress SA node automaticity.
• IV induction agent have limited effect on usual clinical doses.• Opioids can depress cardiac conduction.• LA associated with systemic toxicity.
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GOALS OF ANAESTHESIA IN CVS DISEASES• PREMEDICATE BY BZP’S• BLUNT RESPONSE BY LARYGOSCOPY N INTUBATION• AVOID TACHYCARDIA• AVOID HYPOCAPNIA
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THANK YOU
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FOR MORE MEDICAL PRESENTATIONS VISITSlideshare/Dr. Armaan Singh