Heart as a PumpDepartemen FisiologiFakultas Kedokteran Universitas Sumatera Utara

CARDIAC CYCLE

SystoleIso-volumetric contraction : Contraction begins but valves still closed.Tension develops but no shortening of cells.Pressure builds up until pressures in left and right ventricles > aorta (80 mm Hg) and pulmonary artery (10 mm Hg) (lasts about 0.05 s).Ventricular ejection:Pventricles > Paortic/pulmonary trunk.Semilunar valves open (aortic and pulmonary).Muscle cells shorten.Blood expelled: end systolic volume (ESV) remains.

Left Atrial Pressure (7/0 mmHg)Filling

Left Ventricular Pressure (120/0 mmHg)Filling

Aortic Pressure (120/80 mmHg)Filling

Heart SoundsNormally heard by a stethoscopeFirst sound : low, slightly prolonged lub, caused by closure of mitral and tricuspid valves, at ventricular systole. Duration 0.15 s & fequency 25-45 Hz.Second sound ; shorter, high-pitched dup, caused by closure aortic and pulmonary valves, after end of ventricular systole. 0.12 s & 50 Hz.

Third sound : soft, low-pitched, at one-third diastole, period rapid ventricular filling , due to inrush of blood. In young individuals. 0.1 s.Fourth sound : when atrial pressure is high and ventricle is stiff in ventricular hypertrophy , due to ventricular filling, before first sound.

Murmurs or Bruitsabnormal sounds heard in various parts of the vascular system.Bruits heard over a large, highly vascular goiter, over carotid artery when its lumen is narrowed & distorted by atherosclerosis.Murmurs heard over aneurysmal dilation of large arteries, an arteriovenous (A-V) fistula, or patent ductus arteriosus.

Soft systolic murmur are common in individuals, escpecially in children, who have no cardiac disease.Systolic murmurs are also common in anemic patients as a result of low viscosity of blood and rapid flow.

Cardiac Output (CO)Volume darah yang dipompakan ventrikel dalam unit waktuCO = HR X SVContoh :HR (denyut jantung) = 70 X/1mnt SV (stroke volume) = 70 ml/1 XCO = 70 X 70 ml = 4.900 ml/1 menit

CO laki-laki +/- 5,5 ltr/menit wanita +/- 4,15ltr/menit

Distribusi Cardiac OutputCardiac OutputKonsumsi oksigen

Some Definitions

Heart Rate: 60-100 beats/minnumber of contractions per unit time.Stroke Volume: 70-80 mlvolume pumped by a ventricle in one contraction.Cardiac Output: 5-5.5 l/minflow rate out of the heart, volume pumped per unit time. Cardiac Output = Heart Rate x Stroke VolumeVenous return:5-5.5 l/minflow rate into the heart.Diastole: Relaxation of the heart.Systole: Contraction of the heart Diastolic pressure:80 mmHglowest systemic arterial pressure, during diastole.Systolic pressure:120 mmHghighest systemic arterial pressure, during systoleBlood volume5 l

CARDIAC OUTPUTMethod of Measurementdirect Fick method and indicator dilution methodFicks principle : Amount of a substance taken up by an organ (whole body) per unit time = arterial level of the substance minus venous level (A V difference) times blood flow.

Cardiac index = cardiac output per square meter of body surface , averages 3,2 L

Indicator dilution techniqueCardiac output = amount of indicator injected divided by its average concentration in arterial blood after a single circulation through the heart.thermodilution, indicator used is cold saline

Cardiac Output in Various Conditions

Factors Controlling Cardiac Output

Cardiac accelerator action of catecholamines liberated by sympathetic stimulation : chronotropic action, whereas their action on the strength of cardiac contraction : inotropic action.force of contraction of cardiac muscle is dependent upon its preloading and its afterloading. preload is the degree to which the myocardium is stretched before it contracts (= EDV)afterload is the resistance against which blood is expelled (= Aortic Pressure & MAP)

Relation of Tension to Length in Cardiac Muscle Starling's law of the heart or Frank-Starling law = "energy of contraction is proportional to the initial length of cardiac muscle fiber." = relation between ventricular stroke volume and end-diastolic volume

= Length of muscle fiber = preload

Kurva Frank StarlingStroke volumeEnd Diastolic VolumeNormalStimulasi AdrenergikFungsi jantungSyok Kardiogenik

PRESSUREDIASTOLICPRESSURE CURVESYSTOLIC PRESSURE CURVEHEARTEnd Diastolic VolumeEnd Systolic VolumeIsovolumetricPhaseIsotonic (Ejection) PhaseStrokeVolumePre-loadAfter-load

PRESSUREDIASTOLICPRESSURE CURVESYSTOLIC PRESSURE CURVEHEARTEnd Diastolic VolumeEnd Systolic VolumeIsovolumetricPhaseIsotonic (Ejection) PhaseStrokeVolumePre-loadAfter-loadINCREASEDCONTRACTILITY

PRESSUREDIASTOLICPRESSURE CURVESYSTOLIC PRESSURE CURVEHEARTEnd Diastolic VolumeEnd Systolic VolumeIsovolumetricPhaseIsotonic (Ejection) PhaseStrokeVolumePre-loadAfter-loadDECREASEDCONTRACTILITY

PRESSUREDIASTOLICPRESSURE CURVESYSTOLIC PRESSURE CURVEHEARTEnd Diastolic VolumeEnd Systolic VolumeIsovolumetricPhaseIsotonic (Ejection) PhaseStrokeVolumePre-loadAfter-loadINCREASEDFILLING

Myocardial Contractility

Kondisi Jantung NormalKontraksi reguler dan sinkron Katup jantung (normal)Kontraksi kuat Pengisian adequat (diastole)

Kondisi Jantung NormalKontraksi reguler dan sinkron Katup jantung (normal) Kontraksi kuat Pengisian adequat (diastole)Aritmia

Stenose, Regurgitasi

Failure

abnormal filling

Let it beat!

**