cardiovascular system
DESCRIPTION
This PPT is on Cardiovascular System ,prepared By Dr.A.R.Joshi & uploaded by Prof.Dr.R.R.Deshpande on 25-8-13TRANSCRIPT
CARDIOVASCULAR SYSTEM
BY
Dr. A.R. JOSHI
PROFESSOR OF PHYSIOLOGY
CARDIOVASCULAR SYSTEM
Properties of Cardiac Muscle1. Autorhythmicity2. Conductivity3. Contractility4. Excitability5. All or none law6. Long refractory period
Electrodes (leads).
Amplifier
Recording unit
Bipolar leads – I, II, III.
Unipolar leads –
Limb leads – aVR , aVL , aVF
Chest leads – V1 to V6.
P- Wave- Depolarization of atria
QRS Complex- Depolarization of ventricles
T- Wave – Repolarization of ventricles
PR interval – AV conduction time• (0.12 – 0.16 Sec.)
QT interval – Ventricular systole• (0.26 – 0.30 Sec)
TP interval – Ventricular diastole• (0.46 – 0.50 Sec)
ST- Segment should be iso-electric
Diagnosis of arrhythmias & heart blocks.
Diagnosis of hypertrophy. Diagnosis of IHD. Diagnosis of other diseases like
electrolyte imbalance, pericarditis etc.
NERVE SUPPLY OF HEART
Autonomic Nervous SystemSympathetic supply( T1 to T5 )Effects of stimulation(Due to Noradrenalin and Adrenalin )1. Increase in Heart rate2. Increase in Force of contraction3. Increase in Excitability4. Increase in Conductivity(Effects blocked by alpha & beta blockers)
PARA SYMPATHETIC SUPPLY(Lt. & Rt. Vagus)
Effects of Stimulation :(Due to Acetyl Choline )1. Decrease in Heart rate2. Decrease in Force of contraction3. Decrease in Excitability4. Decrease in Conductivity
(All effects reverted by Atropine which blocks muscarinic 2 receptors)
CARDIAC CYCLE Total time – 0.8 sec when HR -75/min.
Events :Atrial events :
1. Atrial systole 0.1 sec2. Atrial diastole 0.7 secVentricular events : 1. Ventricular systole 0.3 sec2. Ventricular diastole 0.5 sec
VENTRICULAR SYSTOLE(contraction)
Events :1. Isovolumetric contraction phase2. Maximum ejection phase 3. Reduced ejection phase (First Heart sound occurs at beginning of Iso-volumetric contraction phase)
VENTRICULAR DIASTOLE(relaxation)
Events :1. Protodiastole2. Isovolumetric relaxation phase3. First rapid filling phase4. Diastasis5. Last rapid filling phase (Second heart sound occurs at beginning
of Isovolumetric relaxation phase )
FIRST HEART SOUNDCauses :
1. Closure of A-V valves 2. Contraction of Ventricles 3. Ejection of blood in big vessels
Peculiarities 1. Like LUBB
2. Intensity high & pitch low 3. More duration 4. Best heard at apex 5. Best heard with diaphragm 6. Coincides with carotid pulse
SECOND HEART SOUNDCauses :
1. Closure of S-L valves 2. Relaxation of Ventricles 3. Regurgitation of blood in big vessels
Peculiarities : 1. Like DUP
2. Intensity low & pitch high 3. Short duration 4. Best heard at base 5. Best heard with bell 6. Comes after carotid pulse
REGULATION OF HEART RATE
1. Nervous factors2. Hormonal factors3. Local factors4. Reflexes : Cardio acceleratory reflex
Cardio inhibitory reflex5. Miscellaneous factors like body temp.
CLINICAL EXAMINATION OF ARTERIAL PULSE
1. Rate2. Rhythm3. Volume4. Force5. Tension6. Equality7. Condition of vessel wall8. Peripheral pulsations9. Apex–pulse co-relation
CARDIAC OUTPUT
1. Stroke Volume (70 ml)2. Minute volume=S.V x H.R.(5 litres/min.)3. End systolic volume (60 ml)4. End diastolic volume (130 ml)5. Ejection systolic fraction (0.55)
=Stroke volume/End diastolic volume (Criterion of cardiac fitness )
FACTORS AFFECTINGSTROKE VOLUME
Venous return (Input factors) :1. Muscle pump2. Respiratory pump3. Blood volume4. Pressure gradient5. Venous tone
FORCE OF CONTRACTRION(Output factors)
1. Nervous factors2. Hormonal factors3. Frank-Starling’s law4. Coronary perfusion5. Diastolic period
CAUSES OF CARDIAC FAILURE
1. Ischaemic 2. Hypertensive 3. Valvular 4. Cardiomyopathies
RIGHT HEART FAILURECauses : COPD
Ischaemia Pulmonary valve diseases Secondary to chronic LVF
Effects: Pitting oedema over feet Prominent neck veins Liver enlargement & ascitis Hepato-jugular reflex present
LEFT HEART FAILURE
Causes : Hypertension Ischaemia Aortic valve diseases
Effects : Pulmonary oedema Basal crepitations Pulsus alternans
(Preferably with hospitalization)
1. Treat the basic cause 2. Oxygenation3. Salt restricted diet 4. Cardiotonic drugs like digitalis5. Drugs to reduce load on heart like diuretics
TREATMENT OF CARDIAC FAILURE
PHYSIOLOGICAL VARIATION
1. Age
2. Sex
3. Exercise
4. Posture
5. Diurnal
6. Mental stress
7. High altitude
FACTORS AFFECTING B.P.
Systolic B.P. depends upon Cardiac output
Diastolic B.P. depends upon Peripheral Resistance, which depends upon-
● Diameter of blood vessel
● Elasticity of blood vessel
● Viscosity of blood
● Velocity of blood
● Length of blood vessel
REGULATION OF B.P.
Short term regulation : Nervous regulation
1. Baroreceptors 2. Chemoreceptors 3. CNS ischemic response Hormonal regulation1. Renin angiotensin2. Catecholamines3. ADH
REGULATION OF B.P.(cont.. )
Intermediate :
1. Vascular stress relaxation
2. Capillary fluid shift mechanism
Long term :
1. Role of aldosterone
2. Role of kidney
HYPERTENSION
Definition :Types : 1. Primary
2. Secondary
Predisposing factors for primary hypertension : 1. Age 2. Sex 3. Heredity 4. Life style(Diet,sedentary work,stress,habits) 5. D.M. and obesity
HYPERTENSION (cont.. )
Symptomatology : ● Asymptomatic ● Classical symptoms ● Complications LVF Encephalopathy and stroke Nephropathy Retinopathy
TREATMENT OF PRIMARY HYPERTENSION
● Mild hypertension :
Life style modification Salt, fat and sugar restriction Tranquillizers if required
● Moderate hypertension : All above Diuretics
● Severe hypertension: All above
Anti hypertensives
ANTIHYPERTENSIVE DRUGS
1. Beta blockers e.g.atenolol
2. Calcium channel blockers e.g.amlodipine
3. ACE inhibitors e.g.captopril
4. Angiotensin receptor blockers e.g.losartan
5. Alpha receptor blockers e.g.doxazocin
SHOCKPersistent hypotension leading to
inadequate tissue perfusion.Types :1. Hypovolemic
2. Cardiogenic 3. Anaphylactic 4. Neurogenic 5. Septic
STAGES OF HYPOVOLEMIC
SHOCK
1. Compensatory : Blood loss upto 500ml
(All B.P.regulating mechanisms working to maximum)
2. Progressive : Blood loss upto 1 litre
(External help in form of fluid or blood transfusion )
3. Irreversible : Blood loss more than 1 litre
(Harmful positive feedback sets in )
PRINCIPLES OF TREATMENT
1. Hospitalization
2. Replacement therapy
3. Drugs e.g dopamine
4. Treatment of complications
e.g renal failure
PECULARITIES OF CORONARY CIRCULATION
(Normal flow –250 ml per min )
1. End arteries2. Filled in diastole3. High capillary density4. A-V difference of oxygen is high5. Local factors regulate blood flow6. Presence of beta receptors7. Energy derived from fatty acids
PECULARITIES OF PULMONARY CIRCULATION
( Normal flow –5lits per min )
1. Low pressure system2. No tissue fluid formation3. Distensible4. Nerves and hormones have no effect5. Hypoxia causes vasoconstriction6. Less blood flow to apex and more to base7. Rich lymphatic supply