PULMONARY ARTERY CATHETERISATION,

TRANSOESOPHAGEAL ECHOCARDIOGRAPHY &2DECHOCARDIOGRAPHY

MODERATOR: DR.MANJUNATHBY: DR. ARATI M. BADGANDI

PULMONARY ARTERY PULMONARY ARTERY CATHETERISATIONCATHETERISATION

Increased amount of diagnostic information obtained in critically ill patients.

With increasing number of patients with multisystem organ dysfunction undergoing cardiac procedures, PAC monitoring prevalent in cardiac surgical settings.

Understanding of PA catheterization therefore essential for anesthesiologists.

1 of main reasons for measuring PCWP & PADP - estimates of LAP, in turn an estimate of LVEDP.

LVEDP - index of LVEDV - correlates well with LV preload.

PAC PLACEMENT

Right IJV technique of choice - direct path to RA. Placement through subclavian vein introducers

complicated by kinking of catheter when sternum is retracted during cardiothoracic surgery.

Considerations for insertion site of a PA catheter - same as CVP catheters.

Passage of PAC from vessel introducer to PA - accomplished by monitoring pressure waveform from distal port of catheter/under fluoroscopic guidance.

Waveform monitoring - common technique for perioperative heart catheterization.

Std PAC 7-9Fr circumference, 110 cm in length marked at 10-cm intervals, with 4 internal lumens.

Distal port at catheter tip for PAP.

2nd 30 cm more proximal – for CVP.

3rd leads to balloon near tip.

4th houses wires for temperature thermistor, end just proximal to balloon.

Requires aid of a skilled assistant.

Before insertion, PAC passed through sterile sheath - attaches to hub of introducer for sterile manipulation of position.

Assistant attaches distal & proximal port hubs to pressure transducers, flushes to ensure proper function & remove air from system.

Balloon tested by filling it completely with 1.5 mL of air from volume-limited syringe - ensure symmetry of expansion & patency.

Air-filled balloon at tip of catheter serves to “float” catheter forward with BF through RH chambers into proper position in PA.

Important to check assembly for proper function.

When tip of PAC held near heart level, recorded pressure should be 0 mm Hg, confirming transducer was correctly adjusted.

Catheter tip raised up straight to create a 30-cm-tall vertical fluid column, which should produce a pressure of 22 mm Hg (= 30 cm H2O) on bedside monitor.

Slightly larger skin nick (than for CVP) -accommodate large-bore introducer sheath with hemostasis valve at outer end & side-arm extension for IV access.

Tapered-tip, stiff dilator stylet placed inside introducer sheath to facilitate passage into vein.

Utmost care when introducing large dilator-cannula assembly by advancing only to depth required to enter vein, & threading introducer into vein.

Guidewire & dilator are removed, introducer sheath is sutured in place.

PAC is inserted through hemostasis valve of introducer to depth of 20 cm or approximately 5 cm beyond tip of introducer sheath.

Characteristic CVP waveform should be visible.

Curvature of PAC should be oriented to point just leftward of sagittal plane (11-o’clock position as viewed from patient's head) to facilitate passage through anteromedially located TV.

Balloon is inflated, catheter is advanced into RA; through TV, RV and PV; into PA; finally into wedge position.

Crossing PV, dicrotic notch appears in pressure waveform - sudden increase in DBP.

PCWP tracing - by advancing catheter 3-5cm till change in waveform & drop in measured mean pressure.

Deflation of balloon - reappearance of PA waveform & increase in mean pressure value.

Characteristic waveforms from each location confirms proper catheter passage & placement.

After PAWP measured, balloon deflated & PAP waveform should reappear.

Wedge pressure obtained as needed by reinflating balloon & allowing catheter to float distally until PA occlusion occurs again.

Tip of PAC advances to smaller pulmonary artery each time balloon is inflated to measure wedge pressure.

In some, tip migrates distally without balloon inflation – esp.in CPB - repeated cardiac manipulations & temperature changes, altering stiffness of PAC.

Proper catheter position ensured by frequent observation of pressure waveform.

Using right IJV approach, RA entered at 25-35 cm, RV at 35-45 cm, PA at 45-55 cm, & PCWP at 50-60 cm in most patients.

When other sites chosen for PAC placement, additional distance is required. (extra 5-10 cm from left IJV & left & right EJV, 15 cm from femoral veins, 30-35 cm from antecubital veins.

Balloon inflated only for short periods to measure PCWP.

If RV waveform not observed after inserting catheter 40 cm, coiling in RA is likely.

Similarly, if PA waveform not observed after inserting catheter 50 cm, coiling in RV has probably occurred.

Balloon should be deflated, catheter withdrawn to 20 cm, & PAC floating sequence repeated.

If PAWP trace appears without balloon inflation/partial inflation, balloon should be deflated & PAC withdrawn several cm to reduce risk of pulmonary vascular injury.

Although external protective sleeve covering PAC intended to maintain sterility during minor adjustments, does not exclude contamination.

PACs should be manipulated only as necessary to maintain proper location.

Many clinicians believe that PAC should be inserted before induction of anesthesia.

Studies showed PAC insertion in awake patient - no MI/deleterious hemodynamic changes after preanesthetic medication & continuation of preoperative cardiac medications.

CXR postoperatively in all patients to check position of PA catheter.

Tip of PAC should be within 2 cm of the cardiac silhouette on std AP CXR.

Location also checked by TEE image of catheter in RA, RV & PA.

ADDITIONAL GUIDELINES Air-filled balloon floats to nondependent regions

as it passes through heart into pulmonary vasculature (patient head down aids flotation past TV).

Tilting patient to right side & placing head up - encourage flotation out of RV.

Deep inspiration during spontaneous ventilation increases venous return & RV output transiently - catheter flotation in patient with low CO.

If initially difficult to place, may be positioned easily when hemodynamic conditions change - after induction of GA & positive-pressure.

INDICATIONS Considerable controversy regarding risk/benefit ratio of

PACs. Routine use indicated in high-risk patients (e.g., ASA 4

or 5) & high-risk procedures (e.g., where large fluid changes/ hemodynamic disturbances expected).

The setting is important - evidence that inadequate training or experience increases risk for complications.

COMPLICATIONS Include almost all occurring with CVP placement

ARRHYTHMIAS Most common- transient arrhythmias, especially

PVCs. Positional maneuver 5-degree head-up & right lateral

tilt – statistically less malignant arrhythmias (compared to Trendelenburg position) during insertion.

Complete Heart Block In preexisting left bundle-branch block LBBB. Due to electrical irritability from PAC tip causing

transient RBBB as it passes through RV outflow tract. Imperative to have an external pacemaker

immediately available/use a pacing PAC in such patients.

ENDOBRONCHIAL HAEMMORHAGE

Iatrogenic rupture of PA - common since advent of PAC monitoring in ICU & operating room.

Several risk factors: advanced age, pulmonary HTN, MS, female sex, Coagulopathy, Distal placement of catheter, Balloon hyperinflation.

Balloon inflation in distal PAs - PA rupture due to high pressures generated by it.

Hypothermic CPB increases risk (distal migration of catheter tip with movement of heart & hardening of PA catheter) - common practice to pull PA catheter back 3-5 cm when CPB instituted.

Hallmark of PAC-induced PA rupture –hemoptysis, life-threatening exsanguination/hypoxemia.

CXR reveals hemothorax/new infiltrate near tip of distally positioned PAC.

Diagnosis made by wedge angiogram - radiopaque dye inj through wedged PAC extravasates into parenchyma - identifies site of arterial disruption.

Protection of uninvolved lung prime importance - tilting patient toward affected side, placement of DLT/lung-separation maneuvers to protect contralateral lung.

Ensuring adequate oxygenation & ventilation.

PEEP applied to affected lung may help control hemorrhage.

Anticoagulation should be reversed unless patient must remain on CPB & bronchoscopy performed to localize & control bleeding.

Bronchial blocker into involved bronchus to tamponade bleeding.

Many require surgical therapy - oversewing involved PA/or resecting involved segment/lobe/lung.

Pulmonary Infarction Rare - Embolization of thrombus on PAC.

Catheter Knotting and Entrapment Due to coiling within RV. Insertion of appropriately sized guidewire under

fluoroscopic guidance - unknotting. Or knot tightened & withdrawn percutaneously with

introducer (if no intracardiac structures entangled). If cardiac structures eg. papillary muscles, entangled in

knotted PAC - surgical intervention may be required.

Valvular Damage Withdrawal of catheter with balloon inflated - injury to

TV/PV. Placement of PAC with balloon deflated - increases risk

of passing between chordae tendineae.

PHYSIOLOGIC CONSIDERATIONS, PREDICTION OF LV FILLING PRESSURES

PAC - measurement of variety of hemodynamic variables, including CO, mixed venous oxygen saturation, & most important, PADP PCWP.

Used to estimate LV filling pressure &, in combination with other clinical information - helps guide administration of fluid & vasoactive drugs.

When PAC floats to wedge position, inflated balloon isolates distal pressure-monitoring orifice from upstream PAP.

Continuous static column of blood connects wedged PAC tip to junction of Pulmonary vein & LA.

Wedging thus extends catheter tip to measure pressure at point at which blood flow resumes on venous side of pulmonary circuit.

As resistance in large pulmonary veins negligible, PAWP - accurate, indirect measurement of pulmonary venous pressure & LAP.

PADP often used as alternative to PAWP - estimate LVFP.

Acceptable in normal circumstances (when pulmonary venous resistance is low, pressure in PA at end of diastole equilibrates with downstream pressure in pulmonary veins & LA.)

PADP – advantage - available for continuous monitoring, while PAWP measured only intermittently.

For PADP/PAWP to be valid estimate of LVFP, column of blood connecting tip of wedged catheter & draining pulmonary vein must be continuous & static.

At microcirculatory level, channel consists of pulmonary capillaries subject to external compression by surrounding alveoli.

West & colleagues - 3-zone model of pulmonary vasculature based on gravitationally determined relationships between relative pressure in PAs, pulmonary veins, & surrounding alveoli.

In West zone 1, alveolar pressure > PA & pulmonary veins, while in zone 2, it is intermediate between these two pressures.

PAC positioned in zone 1 & 2 - highly susceptible to alveolar pressure, & measurements reflect alveolar or airway pressure rather than LVFP.

Tip of PAC must lie in zone 3 for PAWP measurements to be accurate.

Supine position favors zone 3 condition - confirmed by radiographic studies.

In lateral/semi-upright position, zone 2 may expand significantly.

Zones 1 & 2 more extensive when LAP is low, when PAC tip is located vertically above LA, or when alveolar pressure is high.

Clues to incorrectly positioned PAC: 1.absence of normal PAWP a & v waves, 2.marked respiratory variation in PAWP, 3.PADP > PAWP measurement without excessively tall

a/v waves on trace

NORMAL PA WEDGE PRESSURE WAVEFORMS

In SVC/RA, CVP waveform observed, with a, c, v waves & low mean pressure.

Here PAC balloon inflated & catheter advanced until crosses TV to record RVP - rapid systolic upstroke, wide pulse pressure, low diastolic pressure.

Next enters RV outflow tract & floats past PV into main PA.

PVCs common during this period - balloon-tipped catheter strikes RV infundibular wall.

Entry into PA - step-up in diastolic pressure, change in waveform morphology.

May be difficult to distinguish RVP from PAP, if only numeric values examined.

Observation of waveform & diastolic contours allows differentiation.

During diastole, PAP falls due to interruption of flow during PV closure & pressure in RV increases due to of filling from RA.

PAP upstroke slightly precedes radial artery pressure upstroke due to longer duration of LV isovolumic contraction, & time for propagation of pressure wave to distal monitoring site.

PCWP - indirect measurement of pulmonary venous pressure & LAP - should resemble these waveforms, with characteristic a, v waves, x & y descents

Due to interposition of pulmonary vascular bed between PAC tip & LA, PCWP delayed representation of LAP.

160 msec for LAP pulse to traverse pulmonary veins, capillaries, arterioles & arteries.

Due to delay, PCWP a wave follows ECG R wave in early ventricular systole (though a wave end-diastolic event)

To recognize prominent a/v waves in PCWP, not necessary to inflate PAC balloon.

Tall LA a/v waves distorts normal PAP waveform, with a wave inscribed at onset of systolic upstroke & v wave distorting dicrotic notch.

Once waves identified by wedging PAC & comparing PAP & PCWP traces - follow PCWP a & v waves in unwedged PAP rather than repeatedly inflating balloon.

SUMMARY PAWP measured with a balloon-tipped PAC -

delayed, damped estimate of LAP by measuring pressure near junction of pulmonary veins & LA.

Mean wedge pressure should be < mean PAP; otherwise, blood would not flow in an antegrade direction.

PAWP waveform should display small but visible a & v waves if pressure trace is displayed with sufficient gain & resolution on monitor.

ABNORMAL PCWP & PAWP WAVEFORMS

As PAC is longer & passes through cardiac chambers prone to distortions from clot/air bubbles, & motion-related artifacts.

Artifactual spikes - unique morphology & timing. At onset of systole, TV closure accompanied by RV

contraction & ejection - excessive catheter motion most common artifact.

Simultaneous with CVP c wave, may produce artificially low pressure/pressure peak.

Repositioning solves problem.

When balloon overinflated & occludes lumen orifice, termed overwedging – distal PAC migration & eccentric balloon inflation, forcing tip against vessel wall.

Catheter records gradually rising pressure caused by continuous flush system & builds up pressure against obstructed distal opening.

If PAC migrated to more distal position, possible for overwedging without balloon inflation.

Overwedged pressure - devoid of pulsatility, higher than expected, & rises continuously to flush pressure. (Such pattern prompt corrective action.)

When wedge tracing appears during partial balloon inflation - suggests PAC inappropriately located in a smaller, distal branch of PA.

PAC withdrawn before overwedging results in vascular injury/pulmonary infarction.

Pathophysiologic conditions involving LH chambers/valves produce characteristic changes in PA & wedge pressure waveforms.

Tall v wave of MR begins in early systole. Fusion of c & v waves, obliteration of systolic x

descent as isovolumic phase of LV systole eliminated (retrograde ejection of blood into LA).

As prominent v wave of MR generated during ventricular systole, mean wedge pressure overestimates LV filling pressure.

Consequently, in severe MR, LVEDP best estimated by measuring wedge pressure before onset of regurgitant v wave).

Larger the v wave, more the regurgitant v wave distorts PA waveform by giving bifid appearance & obscuring normal end-systolic dicrotic notch.

Giant v waves in VSDs not due to retrograde flow, rather excessive antegrade systolic flow into LA due to intracardiac shunt.

Compared to MR (distorts systolic part of waveform), MS alters diastolic part.

Holodiastolic pressure gradient across MV - increased mean wedge pressure, slurred early diastolic y descent, & tall end-diastolic a wave.

Similar abnormalities in LA myxoma/obstruction to mitral flow.

Increased LV stiffness (e.g., LV infarction, pericardial constriction, AS, & systemic HTN) - changes in wedge pressure as seen in MS.

Here, mean wedge pressure increased & trace displays prominent a wave, but y descent remains steep (as no obstruction to flow across MV).

Advanced MS often coexisting AF, a wave not present in many.

MI detected with PAC in several ways. Ischemia impairs LV relaxation - diastolic

dysfunction, characteristic of demand ischemia. Impaired ventricular relaxation - less compliant LV -

increased LVEDP. Increased LA & wedge pressure, & changes in

morphology of waveforms, with phasic a & v wave more prominent as diastolic filling pressure increases.

In LV ischemia, tall wedge pressure a wave produced by end-diastolic atrial contraction into stiff, incompletely relaxed LV.

Systolic dysfunction - hallmark of supply ischemia, caused by sudden reduction/cessation of coronary BF to region of myocardium.

With severe systolic dysfunction, changes in global LV contractile performance may be detected by hemodynamic monitoring.

As EF falls significantly, LVEDV & P rise, & systemic arterial hypotension & elevated pulmonary diastolic & wedge pressure develop.

When LV distorted/ region of ischemic myocardium underlies papillary muscle - acute MR, termed “papillary muscle ischemia”/“functionalMR.”

Most important problem in PAC monitoring - discerning correct pressure measurement in patients receiving PPV/labored spontaneous respiration/causes of greatly increased intrathoracic pressure.

During PPV, inspiration increases PA & wedge pressure.

By measuring pressures at end-expiration, confounding effect of inspiratory increase in intrathoracic pressure minimized.

Forceful inspiration during spontaneous ventilation - opposite effect, but measurement of pressures at end-expiration eliminates confounding factor.

PACs are multipurpose, provide wide range of supplementary features for therapeutic & diagnostic applications.

Some catheters have added lumen often used as venous infusion line that opens either 20 or 30 cm from the catheter tip.

Others - specific modifications for monitoring continuous CO, RH function, or mixed venous oximetry – expanding types of physiologic information available to those caring for critically ill patients.

Specialized PACs allow temporary endocardial pacing/intracardiac ECG recording & may have combinations of electrodes permanently implanted along its length to allow bipolar ventricular, atrial, or AV pacing.

Others have special lumen that opens in RV, through which thin bipolar wire may be introduced for endocardial ventricular pacing/have separate atrial & ventricular lumens for passage of two pacing wires for bichamber sequential pacing.

Properties of Ultrasound Imaging Techniques Equipment Complications Technique of Probe Passage Anatomy & Views Clinical Applications Intraoperative Indications

In early 1980s, when TEE first used in OR - assessment of global & regional LV function.

Numerous technical advances: biplane & multiplane probes; multifrequency probes; enhanced scanning resolution; color flow, pulsed wave & continuous wave

Doppler; automatic edge detection; Doppler tissue imaging; 3D reconstruction; Digital image processing.

In echo, heart & great vessels insonated with ultrasound (above human audible range).

Ultrasound sent into thoracic cavity, partially reflected by cardiac structures, from which - distance, velocity & density of objects within chest derived.

Wavelength, Frequency, and Velocity Ultrasound beam – continuous/intermittent

train of sound waves emitted by transducer/wave generator, composed of density/ pressure waves & can exist in any medium (exception of vacuum).

Waves characterized by their wavelength, frequency & velocity.

Wavelength - distance between two nearest points of equal pressure/density in an ultrasound beam.

Velocity - speed at which the waves propagate through a medium.

As waves travel past fixed point in ultrasound beam, pressure cycles regularly between high & low value. Number of cycles/s (Hertz) - frequency.

Ultrasound - frequencies above 20,000 Hz (upper limit of human audible range).

Propagation velocity = frequency X length

Piezoelectric crystals convert energy between ultrasound & electrical signals.

When presented with a high-frequency electrical signal, these crystals produce ultrasound energy, directed toward areas to be imaged.

Short ultrasound signal is emitted from the piezoelectric crystal.

After ultrasound wave formation, crystal “listens” for returning echoes for given period of time & pauses before repeating cycle.

This cycle length - pulse repetition frequency (PRF) - long enough to provide time for signal to travel to & return from a given object.

PRFs vary from 1-10 kHz, resulting in 0.1-1.0ms intervals between pulses.

When reflected waves return to piezoelectric crystals, converted into electrical signals - appropriately processed & displayed.

Electronic circuits measure time delay between emitted & received echo (speed of ultrasound through tissue constant, time delay converted into precise distance between transducer & tissue).

M Mode Density & position of all tissues in path of a

narrow ultrasound beam (i.e., along a single line) displayed as scroll on video screen.

Scrolling produces updated, continuously changing time plot of studied tissue section, several seconds in duration.

Timed motion display (normal cardiac tissue always in motion) - M mode.

Limited part of heart observed at one time & image requires considerable interpretation, not currently used as primary imaging technique.

Useful for precise timing of events within cardiac cycle & often used in combination with color flow Doppler imaging for & timing of abnormal flows.

2D Mode By rapid, repetitive scanning along many

different radii within area in shape of a fan (sector), echo generates 2D image of section of the heart.

Image is an anatomic section & can be easily interpreted.

Info on structures & motion in plane of 2D scan updated 30-60 times/second.

Repetitive update produces “live” (real-time) image of heart.

Scanning 2D echo devices image heart by using mechanically-steered transducer/electronically-steered ultrasound beam (phased-array transducer).

Doppler Techniques Most modern scanners combine Doppler

capabilities & 2D imaging capabilities. After desired view of heart obtained by 2D echo,

Doppler beam (represented by a cursor) superimposed.

Operator positions cursor as parallel as possible to assumed direction of BF & empirically adjusts direction of beam to optimize audio & visual representations of reflected Doppler signal.

4 ways to measure blood velocities: pulsed wave high repetition

frequency continuous wave color flow

Color Flow Mapping Doppler scanners - real-time BF within heart as

colors while showing 2D images in black & white.

In addition to showing location, direction, & velocity of cardiac BF, images produced allow estimation of flow acceleration & differentiation of laminar & turbulent BF.

Location in heart where scanner has detected flow toward transducer (top of image sector) is assigned color red.

Color assignment arbitrary, determined by equipment manufacturer & user's color mapping. Flow away from direction of top assigned color blue.

In most common color flow coding scheme, faster the velocity (up to a limit), more intense is color.

Flow velocities that change by more than a preset value within a brief time interval (flow variance) have color green added to red/blue.

Rapidly accelerating laminar flow (change in flow speed) & turbulent flow (change in flow direction) satisfy criteria for rapid changes in velocity.

Brightness of red/blue colors at any location & time is usually proportional to corresponding flow velocity while hue is proportional to temporal rate of change of velocity.

Contrast Echocardiography RBCs scatter ultrasound waves weakly - black

appearance on ultrasound examination. Contrast echo - by injecting nontoxic solutions

with microbubbles (shell surrounding gas). Microbubbles - additional gas-liquid interfaces -

substantially increase strength of returning signal, used to define endocardial borders, optimize Doppler envelope signals & estimate myocardial perfusion.

Contrast echo used to image intracardiac shunts, valvular incompetence, pericardial effusions.

Initial contrast agents - agitated free air in saline or blood/saline solution, (large & unstable, unable to cross pulmonary circulation;effective only for RH contrast).

Due to thin shell, gas quickly leaked into blood with resultant dissolution.

Agents with longer persistence subsequently developed.

All TEE probes - multifrequency transducer mounted on tip of gastroscope housing.

Majority echo examination performed using ultrasound between 3.5-7 MHz.

Tip directed by adjustment of knobs placed at proximal handle.

Most adult probes - two knobs; 1 allows anterior & posterior movement, & other permits side-to-side motion.

Multiplane probes also include control to rotate echocardiographic array from 0-180 degrees.

With ability to advance & withdraw probe & to rotate it, many echo windows are possible.

Another feature common to most probes is temperature sensor to warn of possible heat injury from transducer to esophagus.

Adult probes multiplane (variable orientation of scanning plane) & pediatric probes multiplane/biplane (transverse & longitudinal orientation, parallel to shaft).

Adult probes usually have length of 100 cm, 9-12 mm in diameter.

One limitation of TEE - structures very close to probe are seen only in very narrow sector.

Tips vary in shape & size (1-2 mm wider than shaft). Size of probes requires patient to weigh at least 20 kg.

Adult probes contain 32-64 elements/scanning orientation - image quality directly related to number of elements used.

Pediatric probes mounted on narrower, shorter shaft with smaller transducers, used in patients as small as 1 kg.

Feature often available - ability to alter scanning frequency (lower frequency, such as 3.5 MHz, has greater penetration & more suited for transgastric view) - increases Doppler velocity limits.

Conversely, higher frequencies yield better resolution for detailed imaging.

Absolute contraindications to TEE in intubated patients:

Oesophageal stricture Diverticula Tumor Recent suture lines Known esophageal interruption. Relative contraindications: Symptomatic hiatal hernia Oesophagitis Coagulopathy Oesophageal varices Unexplained upper GI bleeding

Usual technique - place well-lubricated probe in posterior portion of oropharynx with transducer element pointing inferiorly & anteriorly.

Stabilized by looping controls & proximal portion of probe over operator's neck & shoulder.

Left hand elevates mandible by inserting thumb behind teeth, grasping submandibular region with fingers & gently lifting.

Probe advanced against slight even resistance, till loss of resistance detected as tip of passes inferior constrictor muscle (occurs 10 cm past lips in neonates & 20 cm past lips in adults).

Further manipulation under echo guidance.

Difficult TEE probe insertion may be caused:

probe tip abutting the pyriform sinuses, vallecula, posterior tongue,

esophageal diverticulum. Overinflation of ETT tube cuff could obstruct

passage.

Maneuvers that aid passage: changing the neck position, realigning TEE probe, applying additional jaw thrust. may be passed with assistance of DL.

LV carefully examined for global & regional function using multiple transducer planes, depths, rotational & angular orientations.

Analysis of segmental function based on qualitative visual assessment - following grading system of LV wall thickness & motion (endocardial border excursion) during systole:

1 = normal (>30% thickening); 2 = mild hypokinesis (10% to 30% thickening); 3 = severe hypokinesis (<10% thickening); 4 = akinesis (no thickening); 5 = dyskinesis (paradoxical motion).

CVS function - global indices of muscle contraction /regional indices described by segmental wall motion, is assessed by analyzing moving echocardiographic images.

Assessment of global & regional ventricular function cornerstone for evaluating patients with ischemic heart disease (IHD).

Dynamic assessment of ventricular function with echocardiography is based on derived indices of muscle contraction and relaxation.

Echo indices of LV function that incorporate endocardial border outlines and Doppler techniques can be used to estimate CO, stroke volume (SV), ejection fraction (EF), and parameters of ventricular relaxation and filling.

Global LV performance is directly related to preload, contractility, and afterload.

CO reflects systolic function and is an important factor in oxygen delivery.

Alteration in LV diastolic function may result from systolic dysfunction or, in as many as 40% of patients, may be the primary and main etiology of cardiac failure

Visual Estimation of Function

Estimations of global ventricular function performed in short-axis view of LV (additional info can be gained by assessing long-axis views of LV).

Observer examines end-diastolic image & compares it with end-systolic frame to determine degree of ejection. Rate of ejection is also estimated.

RWMAs identified on visual inspection of echocardiographic images by anesthesiologists.

Preload/Diastolic Function

Estimated by measuring LH filling pressures (PCWP, LAP, LVEDP), in echo determined by measuring LVED dimensions.

ED dimensions better index of preload than PCWP.

TEE for practical reasons, limited to single short-axis view at level of papillary muscles.

2 main signs of decreased preload: (1) decrease in EDA (<5.5 cm2/m2) invariably

reflects hypovolemia; (2) obliteration of end-systolic area (ESA)

accompanies decrease in EDA in severe hypovolemia.

Most obvious limitation of TEE - ischemia cannot be detected during critical periods - induction/ laryngoscopy/ intubation/ emergence/extubation.

In addition, the adequacy of RWMA analysis may be influenced by artifact.

Category I  Heart valve repair  Congenital heart surgery  Hypertrophic obstructive cardiomyopathy  Endocarditis  Acute aortic dissection  Acute, unstable aortic aneurysm  Aortic valve function in the setting of aortic

dissection  Traumatic thoracic aortic disruption  Pericardial tamponade

Category II Myocardial ischemia and coronary artery disease Increased risk of hemodynamic disturbances Heart valve replacement Aneurysms of the heart Intracardiac masses Intracardiac foreign bodies Air emboli Intracardiac thrombi Massive pulmonary emboli Traumatic cardiac injury Chronic aortic dissection Chronic aortic aneurysm

Detection of aortic atheromatous disease as a source of emboli

Evaluating the effectiveness of pericardiectomies Heart-lung transplantation Mechanical circulatory support Category III Other cardiomyopathy Emboli during orthopedic procedures Uncomplicated pericarditis Pleuropulmonary disease Placement of intra-aortic balloon pump,

pulmonary artery catheter Monitoring the administration of cardioplegia

In unsecured airway, TTE is easier to perform than TEE - entirely noninvasive.

TTE uses frequencies lower (1 to 3 MHz) than TEE does to penetrate greater distances inherent in transthoracic technique - previously discussed modalities can be performed with TTE.

Probes are different from linear probes used to identify superficial vascular structures & nerve bundles.

TTE uses three standard “windows” (soft tissue points that avoid interposition of bone between the transducer and heart): parasternal (PS), apical (AP), and subcostal (SC).

Examination begins with patient turned halfway onto left side with left arm elevated alongside head.

Optimal imaging requires ultrasound gel between probe & chest wall.

Parasternal long-axis (PS LAX) cross section is acquired first by placing the probe on the left side of the sternum at the level of 4th ICS & directing ultrasound beam toward patient's right shoulder – shows ME LAX in TEE.

Parasternal short-axis (PS SAX) - rotating transducer 90 degrees clockwise & angling inferiorly toward left hip until RV appears - crescent-shaped structure at top of display & LV in SAX is viewed at bottom – same view as TG SAX in TEE.

Apical window - placing transducer in 4th/5th ICS lateral to nipple line with transducer marker pointing toward the floor.

Appropriate adjustment - apical four-chamber (AP-4C) - apex of heart on top of display & right & LA on bottom – same as ME 4C in TEE.

Apical two-chamber (AP-2C) - rotating transducer 60 degrees counterclockwise – same as ME 2C in TEE - reveals segmental function of anterior & inferior walls of LV.

Apical long-axis (AP LAX) - rotating transducer counterclockwise another 60 degrees until LV outflow tract & AV seen in bottom of display – same as ME LAX in TEE.

Last 2 sections - from subcostal window with patient supine – transducer flat under right costal ridge next to xiphoid, pointed to left shoulder with marker pointing leftward.

Subcostal 4-chamber (SC-4C) – with upper 1/3 of display occupied by liver & heart below - RV free wall contractility & hemodynamically significant pericardial effusion best viewed.

SC IVC cross section - rotating transducer 90 degrees counterclockwise – IVC seen on left side of display as rectangular echolucent structure inside liver connecting to RA.

Allows assessment of RH filling pressure by evaluating size & collapsibility of IVC in spontaneously breathing patients.

When TEE impracticable & CVS status must be evaluated reliably, TTE can provide same info as TEE.