CARDIAC CYCLE AND JVP
DEPARTMENT OF MEDICINE M V J MEDICAL COLLEGE & R H CHAIRPERSION: PROF: DR .SADASHIVAIAH PRESENTATOR: DR.M.RAMESH BABU
OUT LINEINTRODUCTIONDEFINITIONANATOMY OF THE HEART NORMAL CADIAC CYCLE CAUSES OF ALTERATION IN THE CARDIAC CYCLEJVP DEFINITIONANATOMY AND PHYSIOLOGYMEASUREMENT OF JVPWAVE FORMS OF J VPABNORMAL WAVE FORMS AND CONDITION CAUSING IT
DEFINITION
The cardiac events that occur from the beginning of one heart beat to the beginning of the next are called the cardiac cycle.
CARDIAC CYCLE CONTINUED…. Each cycle is initiated by spontaneous
generation of an action potential in the sinus node.
This node is located in the superior lateral wall of the right atrium near the opening of the SVC,and the action potential travels from here to both atria and then through the a-v bundle into the ventricles.
CONDUCTION SYSTEM
SAN
ANT I/N TRACT OF BACHMAN
MIDDLE I/N TRACT OF
WENCKEBACH
POST I/N TRACT OF THOREL
AVN
LBB
RBB LAF LPF
BUNDLE OF HIS
PURKINJE SYSTEMMyocardium
CONTINUED.. There is a delay of more than 0.1 sec
during the passage of the cardiac impulse from the atria into the ventricles.
This allow the atria to contract ahead of ventricular contraction
The atria acts as a primer pumps for the ventricles.
AP IN A VENTRICULAR MUSCLE FIBRE
Phase 0 : rapid depolarization – opening of fast Na channels Phase 1 : rapid repolarisation – closure of Na channels Phase 2 : Plateau – slow prolonged opening of Ca channels Phase 3 : final repolarisation – rapid efflux of k+ channels Phase 4 : RMP (-85 to -90 mv) – opening of K channels
DIASTOLE AND SYSTOLE The caridac cycle consist of a period of relaxation
called diastole,during which the heart fills with the blood, fallowed by a period of contraction called systole.
Duration of cardiac cycle is the reciprocal of the heart rate.
If H.R -72/min, the duration of c. cycle -1/72 beats/min – about 0.0139 min/beat,or 0.833sec/beat
Duration of systole is 0.3 sec Duration of diastole is 0.5 sec
EFFECT OF HEART RATE ON DURATION OF CARDIAC CYCLE
When heart rate increases, the duration of cardiac cycle decreases , including the contraction and relaxation phases.
The period of systole decreases but not by as great a percentage as diastole.
The heart beating at a very fast rate does not remain relaxed along enough to allow complete filling of the cardiac chambers before the next contraction.
ATRIA AS PRIMER PUMPS About 80% of the blood flows directly
through the atria into the ventricles even before the atria contract.
Atrial contraction usally cause an addition 20% filling of the ventricles.
Normally atria has the capability of pumping 300-400% more blood than is required by the resting body.
CARDIAC CYCLE AND EVENTS
EVENTS OF CARDIAC CYCLE Filling of the ventricles during the
diastole. Period of rapid filling of the ventricles
lasts for about 1/3 rd of diastole. middle 1/3 rd only small amount of
blood normally flows into ventricles, during last 1/3 rd of diastole atria
contracts and give additional inflow for about 20%.
EMPTYING OF THE VENTRICLES DURING SYSTOLEPERIOD OF ISOVOLUMIC CONTRACTION
The ventricular pressure rises abruptly causing the a-v valves to close.
Additional 0.02-0.03sec is required for the ventricle to build up sufficient pressure to push the semilunar valves.
In this period contraction starts but no emptying. So called isovolumic or isometric contraction.
PERIOD OF EJECTION
When the L V pressure raises slightly > 80mm hg ( R V pressure >8mm hg ), the ventricular pressure pushes the semilunar valves open..
Period of rapid ejection –70% during first 1/3rd remaining 30% emptying during next 2/3rd –period of slow ejection.
PERIOD OF ISOMETRIC RELAXATION At the end of systole,ventricular relaxation
begins suddenly,allowing both the R & L intraventricular pressures to decrase rapidly.
Elevated pressures in the large arteries ,immediately push blood backward towards the ventricles, which snaps the semilunar valves to close.
Another 0.03-0.06sec requires for full relaxation of the ventricles (isovolumic relaxation).
A-v valves opens to begin a new cycle.
END DIASTOLIC VOLUME, END SYSTOLIC VOLUME & SYSTOLIC VOLUME OUTPUT
During diastole filling to about 110-120ml,this volume called end diastolic volume.
Ventricles emptying during systole ,the decreases to about 70ml- called the stroke volume output.
Remaining volume in each ventricle about 40-50ml is called end systolic volume.
The fraction of the end diastolic volume that is ejected is called the ejection fraction ~60%.
CONT… When heart contracts strongly, the ESV
can be decreased to as little as 10-20ml. When large amount of blood flow into the
ventricles during diastole, the ventricular EDV can become as great as 150-180ml in healthy heart.
By both Increasing EDV and decreasing ESV,the stroke volume output can be increased to more than double normal.
FUNCTIONS OF THE VALVES A.V. valves prevent blood flow from the
ventricles to atria during systole. Semilunar valves prevent blood flow from the
large arteries into ventricles during diastole. These valves open & closes passively,they
closes when back ward pressure gradient pushes, opens when the gradient forces blood in the forward direction
Thin A.V valves require no backflow, semilunar valves require rapid backflow for few mill.sec.
FUNCTIONS OF PAPILLARY MUSCLES
The papillary muscles contract when the ventricular walls contract, but they do not help the valves to close.
They pull the vanes of valves inward toward the ventricles to prevent their bulging.
If chorda tendinea ruptures the valves bulges far backward,results in severe or lethal cardiac incapacity.
SEMILUNAR VALVES
The high pressures in the arteries at the end of systole cause the semilunar valves to snap to the closed position.,much softer closer.
Smaller openings ,the ejection through the aortic and pulmanary valves is far greater than that through the a-v valves.
Strong yet pliable fibrous tissue base to withstand the extra physical stress.
VENTRICULAR PRESSURE- VOLUME LOOP
a – Ventricular filling 1 – Mitral valve closesb – isovol contraction 2 – Aortic valve opensc – ejection 3 – Aortic valve closesd – isovol relaxation 4 – Mitral valve opens
The filling phase moves along the end-diastolic pressure-volume relationship (EDPVR)
The slope of the EDPVR is the reciprocal of Ventricular Compliance
The maximal pressure that can be developed by the ventricle at any given left ventricular volume → end-systolic pressure-volume relationship (ESPVR), which represents the inotropic state.
↓ slope of ESPVR i.e. ↑ ESV
Compensatory rise in preload i.e. ↑ EDV
↓ SV
↓ EF
↓ Work
↑ EDP
Impaired ventricular contraction
SYSTOLIC DYSFUNCTION
Reduced venous return / compliance / relaxation (lusitropy)
↓ EDV
↓ SV
↓ or = EF
↓ Work
↑ EDP
DIASTOLIC DYSFUNCTION
Impaired LV filling
↓ EDV
↓ afterload ; ↓ ESV
↓ SV and CO
MITRAL STENOSIS
Afterload on LV ↓ Outflow resistance is ↓
EDV and EDP ↑
↑ SV
↓ EF
MITRAL REGURGITATION
High outflow resistance; LV emptying impaired
↑ Peak systolic pressure; ↑ afterload
↓ SV
↑ ESV
↑ EDV
AORTIC STENOSIS
No true isovolumetric relaxation
Blood from aorta to ventricle throughout diastole
↑ EDV
↑ SV (if no failure)
↑ ESV and ↓ SV in failure
AORTIC REGURGITATION
ECG TO THE CARDIAC CYCLE
ECG TO THE CARDIAC CYCLE
In Atrial systole Heart sounds - S 4 – pathological. Vibration of the ventricular wall during atrial contraction. Heard in ‘stiff’ ventricle like in hypertrophy and in elderly. Also heard in massive pulmonary embolism, cor pulmonale, TR In isometric contraction Heart Sounds – S1 : closure of the AV valves. Normally split as mitral valve closure preceeds tricuspid valve closure.
In Ejection Heart sounds – none In Isovolumic relaxation Heart sounds – S2 : closure of the
semilunar valves. Normally split because aortic valve closes slightly earlier than the pulmonary valve Heart sounds - S3 - Pathological in adults. Seen in dilated congestive heart failure, MI, MR, severe hypertension. Normal in children
DEFINITION Jugular Venous Pulse: defined as the oscillating top of
vertical column of blood in right IJV that reflects pressure changes in Right Atrium in cardiac cycle.
Jugular Venous Pressure: Vertical height of oscillating
column of blood.
WHY INTERNAL JUGULAR VEIN? IJV has a direct course to RA. IJV is anatomically closer to RA. IJV has no valves( Valves in EJV prevent
transmission of RA pressure) Vasoconstriction Secondary to
hypotension ( in CCF) can make EJV small and barely visible.
WHY RIGHT INTERNAL JUGULAR VEIN? Right jugular veins extend in an almost
straight line to superior vena cava, thus favouring transmission of the haemodynamic changes from the right atrium.
The left innominate vein is not in a straight line and may be kinked or compressed between Aortic Arch and sternum, by a dilated aorta, or by an aneurysm.
The patient should lie comfortably during the examination.
Clothing should be removed from the neck and upper thorax.
Patient reclining with head elevated 45 °
Neck should not be sharply flexed.
Examined effectively by shining a light tangentially across the neck.
There should not be any tight bands around abdomen
METHOD OF EXAMINATION
the level of venous pressure.
the type of venous wave pattern.
OBSERVATIONS MADE
Using a centimeter ruler, measure the vertical distance
between the angle of Louis (manubrio sternal joint) and the
highest level of jugular vein pulsation.
The upper limit of normal is 4 cm above the sternal angle,.
Add 5 cm to measure central venous pressure since right
atrium is 5 cm below the sternal angle. Normal CVP is < 9 cm H2O
THE LEVEL OF VENOUS PRESSURE
The level of venous pressure
The normal JVP reflects phasic pressure changes in the right atrium and consists of three positive waves and two negative troughs
Simultaneous palpation of the left carotid artery aids the examiner in relating the venous pulsations to the timing of the cardiac cycle.
NORMAL PATTERN OF THE JUGULAR VENOUS PULSE
Venous distension due to RA contraction Retrograde blood flow into SVC and IJV occurs just after the P of ECG,preceeds S1 Precede Carotid pulse
a wave
The x descent: is due to X Atrial relaxation X` Descent of the floor of the right
atrium during right ventricular systole. Begins during systole and ends before S2
The c wave: Occurs simultaneously with the carotid
pulse Artifact by Carotid pulsation Bulging of TV into RA during ICP
‘V’ WAVE
Rising right atrial pressure when blood flows into the right atrium during ventricular systole when the tricuspid valve is shut.
Synchronous with Carotid pulse Begins in late systole, Peaks after S2 and ends in
early diastole
The decline in right atrial pressure when the tricuspid valve reopens in early diastole.
It begins and ends during diastole.
Y DESCENT
The x descent occurs just prior to the second heart sound (during systole) , while the y descent occurs after the second heart sound (during diastole).
Normally X descent is more prominent than Y descent. Y descent is only sometimes seen during diastole. Descents are better seen than positive waves.
The a wave occurs just before the first sound or carotid pulse and has a sharp rise and fall.
The v wave occurs just after the arterial pulse and has a slower undulating pattern.
The c wave is never seen normally.
IDENTIFYING WAVE FORMS
A. Low jugular venous pressure
1. Hypovolaemia.
ABNORMALITIES OF JUGULAR VENOUS PULSE
1. Intravascular volume overload conditions Right heart failure Valvular Heart Disease with CCF Cardiomyopathy with CCF 2. Constrictive pericarditis.3. Pericardial effusion with tamponade
B. ELEVATED JUGULAR VENOUS PRESSURE
Increased
Resistance to RV Filling.
Tricuspid stenosisR Heart Failure PS PAH
ELEVATED “A” WAVE
Atrial-ventricular Dissociation
(atria contract against
a closed tricuspid valve)
Complete heart block
Ventricular tachycardia
Ventricular pacingJunctional rhythmJunctional
tachycardia.
CANNON “A” WAVE
ABSENT ‘A’ WAVE 1. Atrial fibrillation
1. Tricuspid regurgitation.2. Right ventricular failure.3. Restrictive cardiomyopathy.4. Cor Pulmonale
ELEVATED “V” WAVE
Absent X Decsent CV/ Regurgitant Wave Has a rounded contour
and a sustained peak Followed by a rapid
deep Y descent Amplitude of V
increases with inspiration.
Cause subtle motion of ear lobe with each heart beat
TRICUSPID REGURGITATION
ASDProminent X descent
followed by a large V wave
M ConfigurationIndicates a large L-R
shuntWith PAH A wave
becomes more prominent.
“A” WAVE EQUAL TO “V” WAVE
1. Cardiac tamponade.2. Constrictive Pericarditis3. RVMI4. Restrictive Cardiomyopathy5. Atrial septal defect
Blunted “x” descent1. Tricuspid regurgitation.2. Right atrial ischaemia
PROMINENT “X” DESCENT
PROMINENT “Y” DESCENT
1. Constrictive pericarditis. 2. Tricuspid regurgitation.
Absent “y” descent1. Cardiac tamponade.
2. Right ventricular infarction3. Restrictive Cardiomyopathy
Slow “y” descent1. Tricuspid stenosis.2. Right atrial myxoma.
M shaped contour Prominent X and Y descent (FRIEDREICH`SIGN) Y descent is prominent as ventricular filling is
unimpeded during early diastole. This is interrupted by a rapid raise in pressure as
the filling is impeded by constricting Pericardium The Ventriclar pressure curve exhibit Square Root
sign
CONSTRICTIVE PERICARDITIS.
A positive response is defined by a sustained rise of more than 3cm in jvp for at least 15s after release of the hand.
Most common cause of a positive test is RHF Positive test in: Borderline elevation of JVP Silent TR Latent RHF False positive: Fluid overload False Negative: SVC/IVC obstruction Budd Chiari syndrome Positive Test imply SVC and IVC are patent
ABDOMINO-JUGULAR REFLUX
Failure of decline in JVP during inspiration. Constrictive Pericarditis Severe RHF Restrictive Cardiomyopathy Tricuspid Stenosis
KUSSMAUL’S SIGN
BIBLIOGRAPHY Ganong’s textbook of Physiology Guyton’s book of Physiology Harrison’s principles of Internal
Medicine Textbook of Cardiology by Jonathan
Abraham Hurst textbook of Cardiology
THANK YOU