CARDIAC PRESSURES

CARDIAC PRESSURES17 DECEMBR 2015POST GRADUATE CENTREMUNADIA MOHAMED

The word HEMODYNAMIC is derived from two Greek words meaning blood and power, which literally means Blood movement The study of the circulatory system.

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HEMODYNAMIC PRINCIPLESEvery electrical activity is followed normally by a mechanical function (either contraction or relaxation) resulting in a pressure wave.

The timing of mechanical events can be obtained by looking at the ECG and corresponding pressure tracings.

The amplitude and duration influenced by both mechanical and physiological parameters (Force of contraction of a chamber , Heart rate and respiration).

The word HEMODYNAMIC is derived from two Greek words meaning blood and power, which literally means Blood movement The study of the circulatory system.

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CARDIAC PRESSURESBlood pressure is measured in various parts of the circulatory system, most notably in the chambers of the heart.Pressure is defined as the force per area hence what is measured is the pressure exerted on the blood by the heart and the force of the pumping action of the heart.A fluid filled catheter is attached to the pressure transducer. The wave is transmitted from the catheter tip to the transducer by fluid column in the catheter.

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ELIMINATION OF SOURCES OF ERRORCalibrated pressure transducerBubble freeLow density liquid (e.g. NaCl 0.9%)Mid Chest level

WIGGERS DIAGRAM

WIGGERS DIAGRAM

MEAN ARTERIAL PRESSUREMean Arterial Pressure (MAP) is defined as the average arterial blood pressure during a cardiac cycle.It reflects the hemodynamic perfusion pressure of all vital organs.MAP = [ ( 2x Diastolic ) + Systolic ] / 3A MAP of at least 60 is necessary to perfuse the coronary arteries, brain and kidneys.Normal Range : 70 100mmHg

MEAN ARTERIAL BLOOD PRESSURE

AORTIC PRESSUREThe Aortic pressure shows the amount of contractile force under which the blood has entered the systemic circulation.Similar in shape to the pulmonary artery waveform with a higher amplitude and no respiratory waveform ( normally).Normal Values:SYSTOLIC: 100 140 mmHgEND DIASTOLIC : 60 90mmHgMEAN PRESSURE: 70 100mmHg

AORTIC PRESSURE

PULMONARY ARTERYThe pulmonary artery channels blood from the right heart into the lungs. During systole, when the pressure in the right ventricle exceeds that of the pulmonary artery the pulmonic valve opens and there is a rapid rise in pressure.The systolic peak corresponds to onset of the T wave on the ECG.At end of systole with the onset of ventricular relaxation, the pulmonic valve closes, reflected in the dicrotic notch.

Normal Range:SYSTOLIC: 15 -30 mmHgEND DIASTOLIC : 3 12 mmHgMEAN PRESSURE: 9 - 16mmHg

PULMONARY ARTERY

Cont..High pulmonary artery pressures seen with:Pulmonary EmboliMV StenosisCOPDPulmonary HypertensionLeft Ventricular FailurePeripheral PA Stenosis

VENTRICULAR PRESSURESRight and left ventricular morphology is similarDiffers with respect to the magnitude of pressure.

RIGHT VENTRICLE:The function of the right ventricle is to pump venous blood into the pulmonary circulation. The mechanical systole begins at the end of QRS complex on the ECG.The RVEDP, is the pressure in the ventricle when the atrium has completed its contraction and the tricuspid valve closes just as the ventricular contraction begins.RVEDP indicates how well the ventricle is filling, how well hydrated the patient is and how elastic myocardium is.

RV Waveform

VENTRICULAR PRESSURESLEFT VENTRICLE:The left ventricle is responsible for generating enough contractile force to pump blood throughout the body. The LVEDP is the pressure at the end of diastole in LV. Corresponds to the R Deflection of the QRS complex.High LVEDP caused by:Aortic valve insufficiencyAbnormal Diastolic functionNormal Values:SYSTOLIC: 100 - 140 mmHgEND DIASTOLIC : 3 - 12 mmHg

LV waveform

VENOUS PRESSURES

RIGHT ATRIAL PRESSURE3 Positive deflections (a, c and v waves)2 negative deflections (x, y)The A wave is caused by a rise in pressure in the atrium during atrial contraction, follows the P wave on the ECG. Height depends on force of contraction and resistance to RV filling.The x descent follows the A wave.Relaxation of the atrium (Pressure in the atrium falls).

RIGHT ATRIAL PRESSUREThe c wave : As the pressure in the ventricle increases the tricuspid valve closes, which causes a small increase in the pressure in atrium. The c wave is found in line with the end of the QRS complex on the ECG.The v wave : When atrial contraction is completed and TV is closed, the pressure in atrium falls. Followed by passive atrial filling.Height depends on RA compliance and amount of blood returning from periphery. Smaller than a wave

VENOUS PRESSURESThe y descent: After the v waveDuring ventricular relaxation phase, the pressure in the right ventricle falls below that of the right atrium and the tricuspid valve opens emptying blood into the RV.The atrial pressure decreases, causing a downstroke in the waveform, known as the y descent.Normal Values:Mean: 0 8mmHgA wave: 2 10mmHgV wave: 2 10mmHg

PULMONARY CAPILLARY WEDGE PRESSURE

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PULMONARY CAPILLARY WEDGE PRESSURESimilar to LA pressure waveform.Objective is to position the catheter to measure the pressure on the left heart side of the pulmonary tree by temporarily obstructing proximal blood flow from the right heart by balloon-tipped catheter. A wave is found near the QRS complex.

Causes of error.PCW = LA pressure, except when PVR is increased.Damped and delayed due to transmission through the lungs.Not properly occluded capillary or not proper position.

CARDIAC PRESSURES

CARDIAC PRESSURES

RESISTANCE

Pulmonary Vascular ResistanceTotal Peripheral Resistance (TPR) is vascular resistance to the systemic circulation.Resistance is P/FlowPeripheral Vascular Resistance (PVR) is vascular resistance of the pulmonary circulation.

PVR = PA mean PCW mean /Qp

RESISTANCE

Systemic Vascular ResistanceResistance = P/FlowSystemic circulation is a high resistance, high pressure circuitPulmonary circulation is a low resistance, low pressure circuit.SVR = RA mean Ao mean/Qs

REFERENCES1. A Manual For Cath Lab Personnel 3rd Edition, 2000, Watson, S ; Gorski K.A K.L. Gould, R.L. Kirkeeide, M. Buchi Coronary flow reserve as a physiologic measure of stenosis severity J Am Coll Cardiol, 15 (1990), pp. 459474http://content.onlinejacc.org/article.aspx?articleid=2474632&resulthttp://circimaging.ahajournals.org/content/6/6/881.abstractHand book of cardiac hemodynamic and function Jonathon Leipsic, MDand James K. Min, MD 2004 5th edition. CA USA.http://www.cathlabdigest.com/article/Test-Your-Hemodynamic-Knowledge-Part-II%E2%80%93-Answer-Keyhttp://www.invasivecardiology.com/

LIGHT BULB MOMENTS

What is the pathology of above tracing ?

Question 1.

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Question 2.

What is the pathology of above tracing ?

AnswerAS with PDA. Catheter pulls back from LV-AO (with35 mm gradient) then through PDA, into PA (with 13 mm gradient) and finally into RV.

CARDIAC PRESSURES