558
`
`SECTION VII INTER VENTIONAL TECHNIQUES
`
`restriction
`
`passage of the balloon into the guiding catheter
`down the proximal vessel and across the lesion
`Once the dilatation catheter has been posi
`tioned within the target stenosis the balloon is
`screw-powered
`inflated progressively using
`handheld inflation device equipped with
`pres
`sure dial At low pressure i.e to
`atm or
`30 to 60 psi the balloon typically has an hour
`due to its central
`glass appearance
`by the coronary stenosis being treated In soft
`lesions this restriction or waist may expand
`as pressure is gradually increased allowing the
`balloon to assume its full cylindrical shape in
`more rigid lesions the restriction may remain
`the balloon expands abruptly at
`prominent until
`stenosis yield pressure that may be any
`and 10 atm 60 to 150 psi
`where between
`28 Some operators increase pressure rapidly
`until all balloon deformity resolves in the hope
`that pushing rigid lesions to higher pressure will
`produce further balloon expansion but
`this in
`creases the risk of dissection when
`fibrotic or
`calcified plaque yields suddenly With the avail
`ability of effective tools for dealing with such
`fibrotic or calcific plaques i.e the Rotablator
`see Chapter 24 one must then consider whether
`plaque that resists ex
`is preferable to treat
`than
`pansion at 10 atm by rotablation rather
`pushing to the pressures 15 to 20 atm or 225
`to 300 psi Fig 23.5 that may be required for
`full dilation Calcified or fibrotic rigid stenoses
`resist expansion at conventional pressures but
`elastic usually eccentric stenoses are also prob
`lematic These lesions allow full balloon expan
`then tend to recoil
`low pressures but
`sion at
`promptly once the balloon is deflated This type
`of lesion was once treated by repeated inflations
`or cautious use of oversized balloons but
`they
`are now treated routinely by stenting with or
`without prior debulking by directional atherec
`tomy The cutting balloon its surface modi
`fied by the application of three to four micro
`scopic blades that protrude slightly above
`the
`balloon surface when inflated has also been
`used for fibrotic or elastic lesions 29
`Despite the more than 20-year history of bal
`little objective sci
`loon angioplasty there is still
`ence behind the speed and maximal pressure
`dilatation balloon The classic
`used to inflate
`
`it
`
`to
`
`approach is to go deliberately over 10 to 15
`pressure that resolves the balloon
`seconds to
`waist and then maintain that pressure for min
`ute On the other hand some operators prefer
`inflation and are prepared to
`slower
`speed of
`tolerate mild persistent balloon defonnities that
`atm
`have failed to resolve at moderate
`pressure 30 Fig 23.6 although the evidence
`inconclushe 31
`for improved outcome is still
`In addition to this operator-to operator variabil
`ity in inflation speed there is wide variation in
`the duration of inflation Early data from Kalten
`bach et al 32 suggested that
`inflations of
`minute might offer more benefit
`than the 30-
`second inflations used in the early l980s Even
`longer 15-minute inflations with
`perfusion
`balloon may produce slightly better acute re
`in long-term patency
`sults with no difference
`10
`
`inflation strategy is selected the re
`Whatever
`sponse of each lesion to balloon dilatation must
`then be assessed individually so that the dilata
`tion protocol can be tailored to achieve the best
`possible result The most common way to assess
`lesion response to balloon dilatation is repeat
`the guiding
`performed through
`angiography
`catheter By leaving the exchange-length guide-
`wire in place during such angiography access
`to the distal vessel and the ability to perform
`intervention e.g repeat balloon in
`flation stent placement are maintained Com
`lumen would
`plete normalization of the vessel
`be the ideal end result of coronary angioplasty
`Given the mechanism of angioplasty see later
`success
`discussion the more.typical result of
`30% residual diameter steno
`ful angioplasty is
`3-mm vessel with
`sis i.e 1.9-mm lumen in
`some degree of intimal disruption reflected as
`localized haziness filling defect or dissection
`The operator must decide whether
`this result is
`is needed
`adequate or whether further treatment
`frequently can be ob
`Some additional benefit
`tained by repeated or more prolonged balloon
`minutes rather
`than the
`inflation i.e
`usual minute which may require use of per
`fusion balloon to attenuate associated myocar
`larger balloon may provide
`ischemia
`dial
`greater lumen enlargement This possibility can
`be explored by exploiting any compliance in the
`
`additional
`
`to
`
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`

`CHAPTER 23 CORONARY ANGIOPLASTY
`
`559
`
`atm or 30 psi Left top Long calcified
`FIG 23.6 Demonstration of low-pressure balloon inflation
`lesion in the middle left anterior descending coronary artery small arrows Left center Rotablator
`.75 mm arrow being advanced across the lesion Left bottom Result after application of
`burr
`in lumen long arrow Right top Low-
`Rotablator shows residual stenosis despite improvement
`30 mm balloon shows full expansion of the balloon at either end of the
`2.5
`pressure inflation of
`the lesion arrows Right bottom Despite absence
`lesion but tubular mild constriction throughout
`postdilation angiogram shows excellent
`luminal patency without dissection
`of full balloon inflation
`open arrow Although higher inflation pressure might have produced further lumen enlargement it
`local dissection resulting in the need for stent
`would probably have caused prominent
`implantation
`despite the unfavorable small caliber and long length of
`lesion
`the target
`
`initial balloon e.g inflating it
`to higher pres
`atm or by using
`than
`sure such as 10 rather
`the next-larger balloon size In doing so how
`ever one must weigh any potential
`benefits
`against the clear risk of using an oversized bal
`larger balloon
`loon Although dilatation with
`it also may in
`may improve luminal caliber
`crease the risk of producing
`large dissection
`leading to abrupt vessl closure 26 This cre
`clear dilemma however because better
`is frequently the enemy of good Striving for
`luminal enlargement with balloon an
`perfect
`gioplasty not uncommonly led to conversion of
`
`ates
`
`fair result to one who had to go
`patient with
`to immediately to the operating room for treat
`dissection caused by one more bal
`ment of
`loon inflation
`In the stent era of course much less emphasis
`is placed on pushing the results of balloon angio
`plasty to the maximum Most
`lesions that can
`be stented are stented Even if stenting is not
`planned the mere availability of stenting to treat
`dissection has helped improve
`balloon-induced
`the results of balloon angioplasty by allowing
`to push for the best result knowing
`the operator
`that stenting is always available to fine-tune the
`
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`

`560
`
`SECTION VII INTER VENTIONAL TECHNIQUES
`
`there is persistent stenosis
`angioplasty results if
`of more than 20% or to repair balloon induced
`dissection It remains uncertain what percentage
`provi
`of patients must be stented for such
`results ap
`sional stent strategy to have
`its
`stenting see also
`proach those of preemptive
`Chapter 25 In trials evaluating
`provisional
`stenting upwards of 40% of balloon angioplasty
`patients received stents before short and long-
`term results were as good as those in patients
`who underwent preemptive stenting see Chap
`ter 25 But even stenting in the approximately
`15% of patients with the worst angioplasty out
`comes has substantially improved the results of
`and
`both acute
`success
`balloon angioplasty
`long-term freedom
`as well as
`complications
`from clinical and angiographic restdnosis in the
`control arm of trials comparing new devices
`to balloon angioplästy performed after the 1994
`in the
`of widespread
`introduction
`stenting
`United States In the current view the best posi
`tion for stand-alone balloon angioplasty is in le
`sions that are poorly suited to stentingvessels
`smaller than 2.5 mm with lesions longer than
`30 mm particularly in patients with diabetes
`
`mellitus
`Given the importance of achieving the best
`result and the uncertainty
`acute angiographic
`the acute result as as
`about
`the adequacy of
`number of other tech
`
`sessed angiographically
`niques have been employed to grade the quality
`years of
`In the initial
`of an arigioplasty
`result
`PTCA operators relied heavily on the transste
`notic gradient as an index of dilatation adequacy
`postdilation pressure difference of less
`seeking
`than 15 mm Hg betweefl
`the aortic pressure
`measured through the guiding catheter and the
`pressure measured
`coronary
`artery
`the dilatation catheter In
`through the tip of
`is compli
`practice measurement of the gradient
`cated by the presence of the dilatation catheter
`within the stenosis and the small size of the dila
`lumen these
`tation catheter
`factors together
`with the switch to low-prOfile over-the-wire dii
`ätation catheters led to abandonment of the gra
`dient measurement by 1988 33 There has been
`reawakened interest based on the
`some recent
`availability of newer solid-state pressure-mea
`
`distal
`
`suring guidewires that can be used to assess the
`transstenotic gradient at baseline flow and dur
`ing maximal hyperemia 34
`The fractional flow reserve FFR is defined
`as the ratio of distal coronary pressure to aortic
`pressure during adenosine-induced
`hyperemia
`goal FFR greater than
`see Chapter 18 with
`successful angioplasty The same
`0.95 after
`be done
`type of physiologic assessment can
`using Doppler flow-measuring guidewires to as
`flow ratios or coronary
`sess diastolic/systolic
`flow reserve CFR as an index of baseline lesion
`confirmation of adequate dila
`significance and
`tion Alternatively intravascular ultrasound
`IVUS see Chapter 19 can more accurately
`measurd lumen diameter
`and cross-sectional
`in pro
`area after dilation IVTJS has been helpful
`or
`such as directional atherectomy
`cedures
`stenting where additional dilation is likely to
`provide further improvement in luminal caliber
`It has provided important mechanistic
`insights
`is not used in more
`into balloon angioplasty but
`than 10% to 15% of routine clinical cases be
`time and expense
`cause of the added procedural
`In most laboratories the postdilation angiogram
`remains the gold standard for determining
`result has been obtained
`whether an adequate
`is to perform stand-alone balloon
`and the angiogram shows that
`appropriate attempt at conventional
`technically
`dilatation has produced
`poor result residual
`stenosis greater than 50% prominent dissection
`new
`frank abrupt closure secondary use of
`stent is indicated
`device such as
`Once adequate dilatation is deemed to have
`is common to withdraw the
`been achieved it
`balloon catheter completely from the guiding
`catheter The exchange-length guidewire is then
`for several thin-
`left across the dilated segment
`utes while the treated esse1 is observed over
`several minutes for angiographic deterioration
`through the guiding catheter with the
`Injections
`balloon removed provide excellent angiographic
`visia1ization while the indwelling guidewire
`provides easy access to the dilated segment
`to
`permit readvancement of the balloon if needed
`such
`With more predictable
`interventions
`as
`stenting however
`single set of postprocedure
`
`angioplasty
`
`If
`
`the intent
`
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`

`CHAPTER 23 CORONARY ANGIOPLASTY
`
`561
`
`angiograms in orthogonal views is usually suffi
`cient to document
`suitable result injhe treated
`lesion and the absence of dissections 6i branch
`occlusions in the adjacent portions of the vessel
`Once stability ofthe dilated segment has been
`the guidewire is withdrawn and
`established
`other significant lesions are dilated similarly or
`recovery area
`is transferred to
`the patient
`
`POSTPROCEDURE MANAGEMENT
`
`less
`
`administered
`during
`Although the heparin
`PTCA was once reversed to allow immediate
`removal of the femoral sheaths it lat became
`routine to leave the sheaths in place overnight
`with continued heparin infusion perfusion of the
`30 mL/hr
`and
`lumen Intra-flow II
`sheath
`monitoring for distal limb ischemia This prac
`tice allowed prompt vascular reaccess should de
`layed abrupt closure occur 35 In current
`inter
`however
`such
`delayed
`practice
`ventional
`abrupt closure occurs so infrequently well
`than 1% that most laboratories now remove the
`sheaths later the same day as soon as the heparin
`effect wears off There is no evidence that pro
`longed postprocedure heparin infusion improves
`outcome 36 and there are compelling data that
`same-day ACT guided sheath removal has low
`and
`ered the incidence of femoral complications
`facilitated next-morning discharge The current
`standard is thus to give no further heparin after
`an uncomplicated procedure that has had
`good
`result and then to perform same-
`angiographic
`removal once the ACT has fallen
`day sheath
`below 160 seconds When angioplasty
`is per
`formed with 7F or 8F sheaths control of
`the
`arterial puncture site during sheath removal can
`be achieved with the same manual compression
`techniques used for diagnostic catheterizations
`With larger sheaths or more intense anticoagu
`lation protocols however prolonged compres
`sion more than 30 minutes may be required
`this is better performed ith the use of me
`chanical aid such as Femo-stop USCI or Corn
`pressar Instromedix Sari Diego CA The other
`alternative is to perform immediate sheath re
`moval
`full heparinization by
`in the setting of
`
`tients
`
`using one of the several arterial puncture sealing
`devices now available see Chapter
`After sheath removal
`typically re
`the patient
`for 18 to 24 hours and then
`mains at bedrest
`ambulates before discharge On discharge pa
`calcium channel
`are usually given
`weeks longer if required for an
`blocker
`for
`other indication such as hypertension and aspi
`rin 325 mg/day indefinitely Patients who re
`additional
`ceived
`given
`also
`stent
`are
`therapy ticlopidine or clopidogrel
`antiplatelet
`to weeks With
`good angiographic result
`for
`in the treated lesions marked jelief of ischemic
`symptoms should be expected unless other sig
`nificant disease has been left behind In the pa
`tient with multivessel disease see later discus
`to evaluate
`sion it may be particularly helpful
`the postangioplasty physiologic state by maxi
`few weeks after
`in the first
`mal exercise test
`i.e predischarge exercise
`discharge Earlier
`routine basis
`testing was once performed on
`but has now been largely abandoned due to the
`for groin rebleeding delay of dis
`potential
`charge or the small risk of precipitating throm
`botic closure of the dilatation site Patients may
`return to full activity within 72 hours by which
`time the groin puncture site should have healed
`sufficiently to allow even brisk physical activity
`to have no anginal
`Patients should expect
`symptoms early after discharge Ongoing angi
`nal symptoms suggest persistent untreated dis
`the treatment site On
`poor result at
`ease or
`symptomatic relief fol
`the other hand initial
`lowed by recurrence of symptoms after
`to
`the dilated seg
`months suggests restenosis of
`or more years
`ment Recurrence of symptoms
`suggests progres
`after successful angioplasty
`sion of disease at another site Along with educa
`tion regarding these possibilities and their pro
`repeat exercise testing and
`posed management
`catheterization with the possibility of more
`intervention or bypass surgery the
`catheter
`acute angioplasty admission should be viewed as
`an opportunity to educate tFie patient and family
`in lifestyle or drug therapy to
`about changes
`control hypertension or lipid abnormalities and
`to reduce the risk for the progression of athero
`sclerotic disease 37
`
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`

`562
`
`SECTION VII INTER VENTIONAL TECHNIQUES
`
`MECHANISM OF PERCUTANEOUS
`TRANSLUMINAL CORONARY
`ANGIOPLASTY
`
`to the original explanation pro
`According
`and by Gruent
`posed by Dotter and Judkins
`the enlargement of the vessel lumen
`zig et al
`after angioplasty was ascribed to compression
`of the atheromatous plaqueakin to footprints
`in the snow In fact
`true plaque compression
`the observed im
`for the minority of
`accounts
`provement 38 Extrusion of liquid components
`from the plaque does permit some compression
`of soft plaques but contributes minimally to im
`in more fibrotic lesions even when
`provement
`balloon inflation is prolonged to minute Ab
`in plaque volume
`reduction
`sent significant
`improvement after PTCA seems
`most
`luminal
`to result from plaque redistributionmore like
`footprints in wet sand Some of this takes place
`by longitudinal displacement of plaque upstream
`and downstream from the lesion Most improve-
`
`should theoretically
`
`results from con
`ment
`in the lumen however
`the entire vessel seg
`trolled overstretching of
`ment by the PTCA balloon This stretching leads
`to fracture of the intimal plaque partial disrup
`the media and adventitia with conse
`tion of
`quent enlargement of both the lumen and the
`overall outer diameter of the vessel 38 Fig
`full-sized balloon
`23.7 Although use of
`balloon/artery ratio of
`eliminate all narrowing at the treatment site the
`overstretched
`vessel wall
`invariably exhibits
`elastic recoil 3940 after balloon deflation as
`well as some degree of local vasospasm 41
`These processes
`typically leave the stretched
`30% residual stenosis i.e 2-
`vessel with
`mm lumen in 3-mm vessel that has been dilated
`3-mm balloon Newer devices such as
`with
`stenting or directional atherectomy are able to
`provide lower 0% to 10% rather
`than 30%
`residual stenosis by reducing or
`postprocedural
`even eliminating this elastic recoil and vascular
`tone
`
`ii
`
`AB
`
`FIG 23.7 Proposed mechanism of angioplasty
`Deflated balloon positioned across stenosis
`the balloon catheter within the stenotic segment causes cracking of
`the intimal plaque
`Inflation of
`the vessel
`the media and adventitia and expansion of the outer diameter of
`After
`stretching of
`residual stenosis of 30%
`balloon deflation there is partial elastic recoil of the vessel wall
`leaving
`and local plaque disruption that would be evident as haziness of the lumen contours on angiography
`From Willerson JT ed Treatment of heart diseases New York Gower Medical 1992
`
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`CHAPTER 23 CORONARY ANGIOPLASTY
`
`563
`
`FIG 23.8 Normal healing of percutaneous transluminal coronary angioplasty PTCArelated coro
`the immediate post-PTCA angiogram
`nary dissection Compared with the baseline angiogram
`the left anterior descending coronary artery lumen with two small filling
`shows enlargement
`of
`months later
`Follow-up angiogram
`coronary dissection
`defects typical of an uncomplicated
`luminal caliber with complete healing of the localized dissection From Bairn
`shows preservation of
`ed Harrisons principles of
`DS Percutaneous transluminal coronary angioplasty In Braunwald
`internal medicine update VI New York McGraw-Hill 1985
`
`In ldition to wrestling with tendencies of the
`the
`deeper vessel wall
`to exhibit elastic recoil
`operator also must contend with the problems
`produced by localized trauma to more superfi
`cial plaque components This trauma is apparent
`the lumen
`as an almost universal haziness of
`margin in the post-PTCA angiogram reflecting
`superficial plaque injury 42 Greater degrees of
`disruption are reflected by intimal filling defects
`Fig 23.8 contrast
`vessel
`outside the
`caps
`lumen or spiral dissections that may interfere
`with antegrade blood flow Fig 23.9 This local
`IVUS on an
`been
`seen
`on
`disruption has
`gioscopy and on histologic examination of post
`and its extent
`mortem angioplasty
`specimens
`correlates with the risk of an occlusive complica
`tion 43 see Abrupt Closure Given
`the
`amount of angioblasty that
`takes place it
`remarkable that dislodgment and distal emboli
`zation of plaque fragments seemed to be infre
`quent in both experimental studies 44 and most
`early angioplasty procedures Disruption of the
`plaque however may clearly lead to emboliza
`
`is
`
`debris
`
`in
`
`atherosclerotic
`patients
`tion of
`vein by
`undergoing dilatation of
`saphenous
`pass graft and in those with large thrombi adher
`to the lesion 45 In these patient distal em
`ent
`large more than mm plaque
`
`bolization of
`
`reduction
`
`as an abrupt
`is usually manifested
`elements
`cutoff of flow in the embolized distal vessel
`In contrast microembolization of plaque debris
`thrombus may be more common
`or adherent
`than suspected 46 and may contribute to post-
`procedure chest pain and enzyme elevation In
`2% to 5% of angioplasties particularly of vein
`in patients with
`grafts or platelet-rich thrombi
`there may be
`recent myocardial infarction
`in antegrade flow with
`dramatic
`ischemia chest pain
`manifestations
`of severe
`ST-segment elevation This may be caused by
`including seroto
`release of vasoactive agents
`nm which may cause intense arteriolar vaso
`spasm of the distal microvasculature or by liber
`very large number of microemboli that
`ation of
`physically plug the distal microcirculation It
`important to distinguish this no-reflow phe
`nomenon from more proximal causes of flow
`throm
`restriction dissection spasm proximal
`bosis because the no-reflow phenomenon can
`usually be quickly reversed by administration
`calcium channel
`of low doses of intracoronary
`blockers e.g 100 pg of verapamil or 500 1ag
`of diltiazem into the distal vessel 4748 Oth
`ers have reported reversal with distal
`injections
`of other vasodilators such as adenosine or nitro
`prusside but the syndrome is usually not respon
`
`is
`
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`

`564
`
`SECTION VII INTER VENTIONAL
`
`TECHNIQUES
`
`reclosure The appearance of
`right coronary
`FIG 23.9 Coronary dissection leading to abrupt
`coronary angioplasty with an evident
`localized
`and immediately after
`artery stenosis before
`the patient experienced chest
`dissection Within 15 minutes after removal of the dilatation catheter
`pain associated with inferior ST-segment elevation and angiographic evidence of progressive dissec
`in 1980 when this case was done
`Standard management
`tion with impeded antegrade flow
`consisted of emergency bypass surgery which was accomplished without complication Current
`to recross the lesion and tack down the dissection by repeat balloon
`practice would be to attempt
`stent From Baim DS Percutaneous translurriinal angioplasty
`inflation or more likely to place
`guide toward improved results Cardiovasc IntervenRadiol
`analysis of unsuccessful procedures as
`
`1982
`
`sive to nitrates When drug therapy is not effec
`tive at restoring normal flow the patient with
`no reflow will almost certainly go on to sustain
`substantial MI and consideration
`should be
`to intraaortic balloon counterpulsation
`given
`support In patients with vein graft disease alter
`native approaches distal occlusion
`aspiration
`devices or debris filters
`are being investigated
`see
`this problem before it occurs
`to prevent
`Chapter 24
`theoretical possibility with
`Although it
`local stretching trauma frank vessel
`sufficient
`rupture has turned out to be
`rare consequence
`balloon angioplasty bar
`during conventional
`ring the use of significantly oversized balloons
`49 Such vessel perforation is more common
`approximately 1% incidence when new ather
`ectomy devices such as directional atherectomy
`rotational atherectomy or laser angioplasty are
`used 50 see Chapter 24
`
`is
`
`ACUTE RESULTS OF ANGIOPLASTY
`
`Early published data on coronary angioplasty
`derive moStly from the 3000-patient
`success
`
`NHLBI Angioplasty Registry which collected
`1977
`and
`all procedures performed between
`September of 1981 51 Although case selection
`in the registry focused on ideal PTCA candi
`datesthose with proximal discrete concen
`stenoses of
`tric subtotal noncalcified
`single
`vesselthe primary success rate of 63% would
`by current stan
`be considered disappointing
`dards The main explanations
`for this low rath
`were failure to cross the lesion with the dilata
`tion system 29% of cases and failure to dilate
`the lesion adequately once having crossed it
`12% of cases These failures resulted from two
`factors the relative lack of experience of opera
`registry the
`the
`tors contributing cases
`learning curve and the use of original Gruen
`tzig fixed-wire dilatation catheters which had
`comparatively high
`limited maneuverability
`deflated balloon profile and
`low peak inflation
`
`to
`
`pressure
`Despite the inclusion of patients with more
`im
`anatomy progressive
`coronary
`difficult
`in equipment with widespread avail
`provement
`ability of steerable guidewires since 1983 has
`
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`

`CHAPTER 23 CORONARY ANGIOPLASTY
`
`565
`
`undergoing
`
`allowed progressive improvement in the primary
`The
`rate of coronary angioplasty
`success
`second PTCA registry enrolled patients at 14
`centers between 1985 and 1986 52 with
`suc
`cess rate of 90% Moreover analysis of compli
`cations in the 19851986 registry 53 shows
`reduction in the incidence of emer
`concomitant
`gency bypass surgery from 5.8% to 3.5% and
`reduction in the mortality rate for patients with
`disease SVD from 0.85% to
`single-vessel
`0.2% although overall procedural mortality re
`mained close to 1% because of the inclusion of
`greater numbers of patients with multivessel dis
`ease In the late 1980s and early 1990s success
`85% of patients
`was
`obtained
`in roughly
`angioplasty with major
`balloon
`occurring in roughly 6% of pa
`complications
`tients and including death in 1.5% Q-wave Ml
`in 1.5% and emergency surgery in 3% These
`outcomes 1ave improved further with the intro
`duction of new deviceslate 1990s with acute
`success rising to more than 95% and
`procedural
`falling to roughly
`major adverse cardiac events
`3% death 1% emergency surgery 0.7% and
`Q-wave or large nonQ wave MI 1.3%
`an
`angio
`Anatomic
`improvement
`graphically successful PTCA correlates with
`elimination of angirial symptoms and improved
`function on atrial pacing or conventional exer
`cise testing 5455 Studies using thermodilu
`tion videodensitometry and Doppler flow mea
`surement have shown restoration of coronary
`flow reserve after successful coronary angio
`plasty although full normalization may take
`to return see Chapter 18
`matter of weeks
`
`after
`
`COMPLICATIONS
`
`As
`
`specialized form of cardiac catheteriza
`is attended by the
`tion coronary angioplasty
`usual risks related to invasive cardiac procedures
`to diagnostic proce
`see Chapter
`In contrast
`dures the larger-caliber guiding catheter used
`for angioplasty is more likely to result in damage
`to the proximal coronary artery and to cause
`the catheter in
`local bleeding complications
`troduction site Selective advancement of guide-
`
`at
`
`wires and dilatation catheters into diseased coro
`nary arteries may lead to vessel
`
`injury if
`
`they
`
`too aggressively The most
`are manipulated
`common complications of coronary angioplasty
`injury at the dil
`however relate directly to local
`atation site caused as part of the angioplasty pro
`cess 56 as described in the section concerning
`mechanisms se earlier discussion
`
`Coronary Artery Dissection
`
`Although plaque dissection may be caused by
`overly vigorous attempts to pass the guidewire
`tortuops stenotic lumen most dissec
`through
`tions are the result of the controlled injury
`induced intentionally by inflation of the dilata
`tion catheter 3738 In fact
`localized dissec
`tions can be found routinely in animal or cadav
`and
`are evident
`eric models of angioplasty
`angiographically in approximately one half of
`immediately after angioplasty 42
`patients
`When these dissections are small and nonpro
`gressive and do not interfere with antegrade flow
`they have no clinical conse
`in the distal vessel
`quence other than transient mild pleuritic chest
`as soon as
`discomfort Follow up angiography
`weeks after the angioplasty procedure usually
`demonstrates complete healing of the dissected
`segment Fig 23.8 although localized forma
`the site of dissection has
`tion of aneurysm at
`been described 5758
`
`occasionally
`
`Abrupt Closure
`
`Although small dissections may be well toler
`ated large progressive dissections may interfere
`with antegrade flow and lead to total occlusion
`phenomenon known as
`of the dilated segment
`abrupt closure Fig 23.9 With the use of bal
`loon angioplasty alone before the advent of new
`abrupt closure occurred in approxi
`devices
`mateli 5% of patients as the result of compres
`sion of the true lumen by the dissection flap 43
`with superimposed thrombus formation platelet
`or vessel spasm In one study 59
`adhesion
`dissections were evident angio
`postangioplasty
`graphically in 40% of dilated lesions with spiral
`dissectioris 51 in 3.5% of patients
`type
`The presence of
`dissection increased
`type
`the risk of frank or threatened abrupt closure
`than 50% with re
`
`stenosis greater
`
`residual
`
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`
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`

`566
`
`SECTION VH INTER VENTIONAL TECHNIQUES
`
`duced antegrade flow from baseline of 6.1%
`to 28% This finding supports the earlier find
`ings of Ellis et al 60 showing
`five fold in
`crease in abrupt closure with postprocedure dis
`section and stressing the relative importance of
`the postprocedure result as opposed to prepro
`cedure clinical or angiographic variables Table
`23.1 on the risk of abrupt closure
`Most abrupt closures after stand-alone bal
`loon angioplasty developed within minutes after
`the final balloon inflation so that it was desir
`for 10 minutes before
`
`able to observe the patient
`
`laboratory Abrupt
`leaving the catheterization
`closure could also occur up to several hours later
`in 0.5% to 1% of cases particularly as the hep
`anticoagulation wore off Under
`those cr
`cumstances it was heralded by severe chest pain
`
`arm
`
`changes usually
`and clear electrocardiographic
`ST-segment elevation similar to those observed
`during prolonged balloon inflation Before 1985
`most patients who experienced abrupt closure of
`major epicardial coronary artery went directly
`to emergency surgery in an effort to minimize
`
`the amount of consequent myocardial damage
`The rate of emergency surgery was 5% to 6%
`but even with emergency surgery within 90 mm
`the onset of vessel occlusion up to
`utes after
`Q-wave MI 61
`50% of patients sustained
`The development of perfusion cathetersin
`balloons with
`fusion catheters or angioplasty
`
`multiple sideholes along their distal shaft
`to
`allow 40 to 60 mL/min of blood to enter proxi
`to the site of occlusion flow through the
`mal
`lumen and reexit into the lumen distal
`central
`to the point of occlusionallowed patients to
`go to the operating room in
`nonischemic state
`Fig 23.4 reducing the incidence of transmural
`infarction during emergency surgery to approxi
`mately 10% 62 Once it was realized that many
`abrupt closures can be reversed by simply re
`advancing the balloon dilatation catheter across
`the lesion to tack up the dissection via re
`peated balloon inflation 35 Fig 23.10 the
`in half
`to roughly
`emergency surgery rate fell
`3% Prolonged balloon inflations
`up to 20
`minutes using an autoperfusion balloon 63 to
`
`FIG 23.10 Reversal of abrupt closure by repeat balloon inflation Eccentric stenosis in the mid-right
`large dissection curved arrow
`coronary artery left arrow dilates center with production of
`focal dye stain open arrow and retarded distal flow Repeat
`0.5-mm-larger balloon
`inflations with
`catheter using inflation durations of up to minutes tacked up the dissection to provide
`stable
`luminal appearance right arrow Approximately 50% of abrupt closure events can be reversed in
`this manner with up to 90% reversal by use of
`coronary stent
`
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`CHAPTER 23 CORONARY ANGIOPLASTY
`
`567
`
`is still
`
`improved the
`
`limit ongoing ischemiafurther
`ability to reverse abrupt closure
`Since 1993 the availability of coronary stents
`has increased the certainty of reversing abrupt
`closure to almost 90% 64 This success
`has
`made it routine to stent any patient with
`large
`preemptive treat
`postprocedure dissection as
`closure even
`threatened
`ment
`for
`abrupt
`is not apparent With
`when flow compromise
`elective stenting of more than 80% of interven
`tional procedures this problem has been largely
`eliminated and emergency surgery rates having
`fallen below 0.5% Beeause emergency surgery
`required in some cases the recommenda
`in place to perform eleciive coronary
`tion is still
`angioplasty only in sttings where the resources
`for prompt emergency bypass surgery are avail
`able 16
`issues of residual ste
`Beyond the mechanical
`is now clear
`that
`nosis and local dissection it
`platelet-rich clots contribute significantly to the
`abrupt closure process The presence of throm
`in
`defect
`bus reflected as
`globular filling
`creases the risk of abrupt closure from 7.2% to
`27.8% 59 The role of thrombus in abrupt clo
`sure is further supported by an increased risk of
`abrupt closure in patients with
`subtherapeutic
`ACT value 20 and by the reduction of ischemic
`bolus
`end points seen in patients treated with
`plus infusion of various platelet Jib/lila integrin
`blockers Table 23.2 17 Although platelets
`may adhere to damaged vessel walls through
`
`is the activation of the 50000
`other receptors it
`to 80000 glycoprotein lib/lila receptors on each
`platelets surface that allows them to bind avidly
`to librinogen to cause platelet aggregation and
`thrombosis Vessels with moderate local dissec
`antegrade f