The document summarizes key aspects of cardiac catheterization procedures for measuring hemodynamics. It describes the normal cardiac cycle and pressure waveforms. Measurement techniques are outlined for pressures, cardiac output, vascular resistance, and valvular stenosis and regurgitation. Pressure transducers, thermodilution, and Fick methods are discussed for cardiac output. Shunt determinations and quantification using oximetry are also summarized.

1. CATH HEMODYNAMICS
Presenter – Dr Virbhan Balai
Moderator –Y.K Arora

2. Cardiac cycle
• The first stage, " diastole," is when the semilunar
valves (the pulmonary valve and the aortic valve) close,
theatrioventricular (AV) valves (the mitral valve and the tricuspid
valve) open, and the whole heart is relaxed.
• The second stage, "atrial systole," is when the atrium contracts, and
blood flows from atrium to the ventricle.
• The third stage, "isovolumic contraction" is when the ventricles
begin to contract, the AV and semilunar valves close, and there is no
change in volume.
• The fourth stage, "ventricular ejection," is when the ventricles are
contracting and emptying, and the semilunar valves are open.
• During the fifth stage, "isovolumic relaxation time", pressure
decreases, no blood enters the ventricles, the ventricles stop
contracting and begin to relax, and the semilunar valves close due to
the pressure of blood in the aorta.

7. HEMODYNAMIC DATA
The hemodynamic component of the cardiac
catheterization procedure-
Pressure measurements
Measurement of flow (e.g., cardiac output, shunt
flow, flow across a stenotic orifice, regurgitant
flow, and coronary blood flow)
Determination of vascular resistance.

8. Pressure Measurement Systems
• Fluid-Filled Systems. Intravascular pressure is
typically measured with the use of a fluid-filled
catheter attached to a pressure transducer.
• The pressure wave is transmitted from the tip of
the catheter to the transducer by the fluid
column within the catheter.
• Most pressure transducers are disposable
electrical strain gauges. The pressure wave
distorts the diaphragm or wire within the
transducer. This energy

9. The pressure transducer must be calibrated
against a known pressure, and establishment of
a zero reference must be undertaken at the start
of the catheterization procedure.
To “zero” the transducer, the transducer is
placed at the level of the atria, which is
approximately midchest.

10. Micromanometer Catheters. Commercially
available high-fidelity micromanometer
systems have both an end hole and side holes
to allow over-the-wire insertion into the
circulation while also permitting angiography.
Catheters that have two transducers separated
by a short distance are useful for accurate
measurement of gradients across valvular
structures and within ventricular chambers.

11. Normal Pressure Waveforms

13. Atrial Pressure
The right atrial pressure waveform has three positive
deflections, the a, c, and v waves.
The a wave is due to atrial systole and follows the P
wave on the ECG.
The height of the a wave depends on atrial contractility
and resistance to RV filling.
The x descent fo- represents relaxation of the atrium
and downward pulling of the tricuspid annulus by RV
contraction.
The x descent is interrupted by the c wave, which is a
small positive deflection caused by protrusion of the
closed tricuspid valve into the right atrium.

14. The v wave - represents RV systole.
The y descent occurs after the v wave and
reflects opening of the tricuspid valve and
emptying of the right atrium into the right
ventricle.

15. Normal Pressure

18. Normal right- and left-sided heart
pressures

19. Ventricular Pressure
RV and LV waveforms are similar in morphology.
They differ mainly with respect to their
magnitudes.
The durations of systole and isovolumic
contraction and relaxation are longer and the
ejection period is shorter in the left than in the
right ventricle.
There may be a small (5 mm Hg) systolic gradient
between the right ventricle and pulmonary artery.

20. Pathologic Waveforms

32. Cardiac Output Measurements
• Thermodilution
• Fick methods.

33. Fick Method. The Fick principle estimates
cardiac output by using the assumption that
pulmonary blood flow (PBF) is equal to
systemic blood flow (SBF) in the absence of
an intracardiac shunt.

34. Thermodilution cardiac output curves

36. Fick cardiac output (liters/) min=
Oxygen consumption (mL/ min)
A-V02 x1.36xHgb x10
Where A-VO2 is the arterial-venous oxygen
saturation difference, Hgb is the hemoglobin
concentration (mg/dL), and the constant 1.36
is the oxygen-carrying capacity of hemoglobin
(expressed in mL O2/g Hgb).

37. Angiographic Cardiac Output
Angiographic cardiac output and stroke
volume are derived from the following
equations:
Stroke volume =EDV -ESV
Cardiac output = EDV- ESV
Heart rate

38. Determination of Vascular Resistance.

40. • Total pulmonary resistance (TPR):
• TPR = 80(PAm )
Qp

41. Evaluation of Valvular Stenosis
Determination of Pressure Gradients
Aortic Stenosis
Transvalvular pressure gradient is best
measured with a micromanometer catheter and
simultaneous recordings in the left ventricle
and supravalvular aorta.
A dual-lumen pigtail catheter is the most
commonly used and preferred catheter.

42. GENERAL PRINCIPALE
Intermittent frequent flushing of the lumen with heparinized saline

44. Femoral artery pressures should not be used to measure the aortic valve
gradient because peripheral amplification may cause a false decrease in
gradient.

45. Catheters with side holes should be used because damping can
occur with an end-hole catheter.

47. The peak-to-peak gradient measured in the
catheterization laboratory is generally lower
than the peak instantaneous gradient measured
in the echocardiography laboratory.

48. Patients with fixed obstruction (either valvular stenosis or fixed subvalvular
stenosis) will demonstrate a parvus and a tardus in the upstroke of the aortic
pressure,
Right, The left ventricular pressure also has a late peak because of the
mechanism of this dynamic obstruction. LA indicates left atrium.

49. Mitral Stenosis
 The most accurate means of determining the mitral valve gradient is direct
measurement of left atrial pressure by the transseptal technique with
simultaneous measurement of LV pressure.
 Pulmonary capillary wedge pressure is usually substituted for left atrial
pressure because it is more readily obtained.
 Pulmonary wedge pressure may systematically overestimate left atrial
pressure by 2 to 3 mm Hg, thereby increasing the measured mitral valve
gradient.
 Improperly wedged catheters resulting in damped pulmonary artery
pressure recordings further overestimate the severity of mitral stenosis.
 If accurate positioning of the catheter in the wedge position is in doubt, the
position can be confirmed by slow withdrawal of blood for oximetric
analysis.
 Oxygen saturation equal to that in the systemic circulation confirms the
wedge position.

50. Optimally performed with a large-bore end-hole catheter.
measurement.
Right, small-lumen thermodilution catheter. damped pulmonary
artery pressure.

51. The gradient using a pulmonary artery wedge pressure will frequently
overestimate the true transmitral gradient.

53. Right-Sided Valvular Stenosis
In pulmonic stenosis, the valve gradient is
obtained by catheter pull-back from the
pulmonary artery to the right ventricle or by
placement of separate catheters in the right
ventricle and pulmonary artery.
Multi lumen catheters can also be used for
simultaneous pressure recordings.
Tricuspid valve gradients should be assessed with
simultaneous recording of right atrial and RV
pressure.

55. Left, In this patient with restrictive cardiomyopathy, there is a drop in left
ventricular pressure and a drop in right ventricular pressure during inspiration
(Insp).
Right, In this patient with constrictive pericarditis, there is ventricular
discordance, with an increase in right ventricular pressure and a decrease in
left ventricular pressure during inspiration.

57. Calculation of Stenotic Valve Orifice
Areas
 Flow (F) and orifice area (A) are related by the fundamental formula
F=cAV
 Hence,
A= F/cV =
 The maximal discrepancy between the actual mitral valve area and
calculated values was just 0.2 cm2 when the constant 0.85 was used.
 No data were obtained for aortic valves, a limitation noted by the
Gorlins, and a constant of 1.0 was assumed.

59. Assessment of Valvular Regurgitation
According to ACC/AHA guidelines,
hemodynamic evaluation of either aortic or
mitral regurgitant lesions is recommended as
a class I indication when pulmonary artery
pressure is disproportionate.

60. Visual Assessment of Regurgitation
Valvular regurgitation may be assessed
visually by determination of the relative
amount of radiographic contrast medium that
opacifies the chamber proximal to its injection.
Estimation of regurgitation depends on the
volume of regurgitant, as well as on the size
and contractility of the proximal chamber.

61. Sellers and colleagues

62. Regurgitant Fraction
 A gross estimate of the degree of valvular regurgitation may be
obtained by determination of the regurgitant fraction (RF).
 The difference between angiographic stroke volume and forward
stroke volume can be defined as the regurgitant stroke volume.
Regurgitant stroke volume =Angiographic stroke volume - Forwa
rd stroke volume
 The RF is the portion of the angiographic stroke volume that does
not contribute to net cardiac output.
 When compared with visual interpretation, 1+ regurgitation is
roughly equivalent to an RF of 20% or less, 2+ to an RF of 21% to
40%, 3+ to an RF of 41% to 60%, and 4+ to an RF of greater than
60%.

63. Shunt Determinations
 Normally, PBF and SBF are equal.
 Unexplained pulmonary artery oxygen saturation exceeding
80% should raise suspicion for a left-to-right shunt,
 Unexplained arterial desaturation (<93%) may indicate a
right-to-left shunt.
 Arterial desaturation commonly results from alveolar
hypoventilation and associated “physiologic shunting,”
causes of which include oversedation from premedication,
pulmonary disease, pulmonary venous congestion,
pulmonary edema, and cardiogenic shock.
 If arterial desaturation persists after the patient takes several
deep breaths or after administration of 100% oxygen, a
right-to-left shunt is likely.

64. Oximetric Method
The oximetric method is based on blood sampling
from various cardiac chambers for determination
of oxygen saturation.
If the difference in oxygen saturation between
these samples is 8% or greater, a left-to-right
shunt may be present.
Oxygen saturation in the IVC is higher than in the
SVC because the kidneys have lower oxygen
extraction relative to their blood flow than other
organs do.

65. A full saturation run obtains samples from the
high and low IVC; high and low SVC; high,
middle, and low right atrium; RV inflow and
outflow tracts and midcavity; main pulmonary
artery; left or right pulmonary artery;
pulmonary vein and left atrium, if possible;
left ventricle; and distal aorta.

66. Shunt Quantification

67. If a pulmonary vein is not sampled, systemic
arterial oxygen saturation may be substituted,
assuming that it is 95% or greater.
If systemic arterial saturation is less than 93%, a
right-to-left shunt may be present.
If arterial desaturation is present but not
secondary to a right-to-left shunt, systemic
arterial oxygen content is used.
If a right-to-left shunt is present, pulmonary
venous oxygen content is calculated as 98% of the
oxygen capacity.

70. A ratio of less than 1.5 indicates a small left-
to-right shunt.
A ratio of 1.5 to 2.0, a moderate-sized shunt.
A ratio of 2.0 or higher indicates a large left-
to-right shunt.
A flow ratio of less than 1.0 indicates a net
right-to-left shunt.

73. Pharmacologic Maneuvers

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