Ventricular tachycardia.docx

8/15/2019 Ventricular tachycardia.docx

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Ventricular tachycardia (VT) is ≥ 3 consecutive ventricular beats at a rate

≥ 120 beats/min. Symptoms depend on duration and vary rom none to

palpitations to hemodynamic collapse and death. !ia"nosis is by #$%.Treatment o more than brie episodes is &ith cardioversion or

antiarrhythmics dependin" on symptoms. ' necessary lon"termtreatment is &ith an implantable cardioverter deibrillator.

Some e*perts use a cuto rate o ≥ 100 beats/min or VT. +epetitiveventricular rhythms at slo&er rates are called accelerated idioventricular

rhythms or slo& VT, they are usually beni"n and are not treated unless

associated &ith hemodynamic symptoms.

-ost patients &ith VT have a si"niicant heart disorder particularly prior-' or a cardiomyopathy. #lectrolyte abnormalities (particularly

hypoalemia or hypoma"nesemia) acidemia hypo*emia and adverse

dru" eects contribute. The lon" T syndrome (con"enital or acuired) isassociated &ith a particular orm o VT torsades de pointes.

VT may be monomorphic or polymorphic and nonsustained or sustained.

-onomorphic VT results rom a sin"le abnormal ocus or reentrant

path&ay and has re"ular identicalappearin" +S comple*es.olymorphic VT results rom several dierent oci or path&ays and is thus

irre"ular &ith varyin" +S comple*es. onsustained VT lasts 30 sec,

sustained VT lasts ≥ 30 sec or is terminated sooner because ohemodynamic collapse. VT reuently deteriorates to ventricular

ibrillation and thus cardiac arrest (see $ardiac 4rrest).

Symptoms and Signs

VT o short duration or slo& rate may be asymptomatic. Sustained VT is

almost al&ays symptomatic causin" palpitations symptoms o

hemodynamic compromise or sudden cardiac death.

Diagnosis

• #$%

!ia"nosis is by #$% (see 5i". 167 8road +S ventricular tachycardia. ).4ny &ide +S comple* tachycardia (+S ≥ 0.12 sec) should beconsidered VT until proved other&ise. !ia"nosis is supported by #$%

indin"s o dissociated &ave activity usion or capture beats uniormity

o +S vectors in the V leads (concordance) &ith discordant T&avevector (opposite +S vectors) and a rontalplane +S a*is in the

north&est uadrant. !ierential dia"nosis includes supraventricular

tachycardia conducted &ith bundle branch bloc or via an accessory

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path&ay (see Table 37 -odiied 8ru"ada criteria or ventricular

tachycardia. ). 9o&ever because some patients tolerate VT surprisin"ly

&ell concludin" that a &elltolerated &ide +S comple* tachycardiamust be o supraventricular ori"in is a mistae. :sin" dru"s appropriate

or supraventricular tachycardia (e" verapamil

diltia;em

) in patients &ith VT may cause hemodynamic collapse and death.

5i". 16

8road +S ventricular tachycardia.

The +S duration is 1


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sometimes class ' or class ''' antiarrhythmics

• =on"term7 :sually an implantable cardioverterdeibrillator

Acute:

Treatment depends on symptoms and duration o VT. 9ypotensive VT

reuires synchroni;ed directcurrent cardioversion &ith ≥ 100 >oules.Stable sustained VT can be treated &ith 'V class ' or class ''' dru"s (see

Table 17 4ntiarrhythmic !ru"s (Vau"han ?illiams $lassiication) ).

=idocaine

acts uicly but is reuently ineective. ' lidocaine

is ineective 'V procainamide

may be "iven but it may tae up to 1 h to &or. 5ailure o 'V

procainamide

is an indication or cardioversion.

onsustained VT does not reuire immediate treatment unless the runs arereuent or lon" enou"h to cause symptoms. 'n such cases

antiarrhythmics are used as or sustained VT.

Long-term:

The primary "oal is preventin" sudden death rather than simplysuppressin" the arrhythmia. 't is best accomplished by use o an

implantable cardioverterdeibrillator ('$!@see 'mplantable cardioverterdeibrillators ('$!s)). 9o&ever the decision about &hom to treat iscomple* and depends on the estimated probability o liethreatenin" VTs

and the severity o underlyin" heart disorders (see Table A7 'ndications or

'mplantable $ardioverter!eibrillators in Ventricular Tachycardia andVentricular 5ibrillation ).

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=on"term treatment is not reuired &hen the inde* episode o VT

resulted rom a transient cause (e" durin" the A6 h ater onset o -') or areversible cause (acidbase disturbances electrolyte abnormalities

proarrhythmic dru" eect).

'n the absence o a transient or reversible cause patients &ho have had an

episode o sustained VT typically reuire an '$!. -ost patients &ithsustained VT and a si"niicant structural heart disorder should also receive

a Bblocer. ' an '$! cannot be used amiodarone

may be the preerred antiarrhythmic or prevention o sudden death.

8ecause nonsustained VT is a marer or increased ris o sudden death in patients &ith a structural heart disorder such patients (particularly those

&ith an e>ection raction 0.3C) reuire urther evaluation. Such patients

should receive an '$!.

?hen prevention o VTs is important (usually in patients &ho have an

'$! and are havin" reuent episodes o VT) antiarrhythmics ortranscatheter radioreuency or sur"ical ablation o the arrhythmo"enic

substrate is reuired. 4ny class 'a 'b 'c '' or ''' dru" can be used.8ecause Bblocers are sae they are the irst choice unless

contraindicated. ' an additional dru" is reuired sotalol

is commonly used then amiodarone

.

Transcatheter radioreuency ablation is used most commonly in patients

&ho have VT &ith &elldeined syndromes (e" ri"ht ventricular outlo&tract VT or let septal VT D8elhassen VT verapamil


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sensitive VTE) and other&ise healthy hearts.

Key Points

• 4ny &idecomple* (+S ≥ 0.12 sec) tachycardia should be

considered VT until proved other&ise.

• :nstable patients (e" &ith hypotension chest pain) should have

!$ cardioversion &ith ≥ 100 >oules.

• 'V lidocaine

or 'V procainamide

may be tried i the patient is stable.

• atients &ho had an episode o sustained VT &ithout a transient or

reversible cause typically reuire an '$!.

=ast ull revie&/revision Fuly 2012 by =. 8rent -itchell -!

$ontent last modiied September 2013


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Ventricular septal rupture (VS+) is a rare but lethal complication o myocardial inarction (-').

The event occurs 26 days ater an inarction and oten precipitates cardio"enic shoc .D1E Thedierential dia"nosis o postinarction cardio"enic shoc should e*clude ree ventricular &all

rupture and rupture o the papillary muscles. (See the ima"e belo&.)

Ventricular septal deect (VS!) is deect in interventricularseptum (&all dividin" let and ri"ht ventricles o heart).

To avoid the hi"h morbidity and mortality associated &ith this disorder patients should under"o

emer"ency sur"ical treatment.D2 3 A CE 'n current practice postinarction VS+ is reco"ni;ed as a

sur"ical emer"ency and the presence o cardio"enic shoc is an indication or intervention.D


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support have helped lo&er mortality. 'n addition the development o sur"ical techniues to

repair perorations in dierent areas o the septum has led to improved results.

'n current practice patients under"oin" shunt repair tend to be older and are more liely to havereceived thrombolytic a"ents &hich may complicate repair. 4ter successul repair survival and

uality o lie are e*cellent even in patients older than G0 years.D6E

5or inormation ne&s and $-# activities on heart ailure see the 9eart 5ailure +esource

$enter . 5or patient education resources see the 9eart $enter as &ell as Ventricular Septal!eect and 9eart 4ttac .

Pathophysiology

The septal blood supply comes rom branches o the let anterior descendin" coronary artery the

posterior descendin" branch o the ri"ht coronary artery or the circumle* artery &hen it isdominant. 'narction associated &ith a ventricular septal rupture (VS+) is usually transmural and

e*tensive. 4bout


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This "rim pro"nosis results rom an acute volume overload e*acted on both ventricles in a heart

already compromised by a lar"e -' and occasionally by e*tensive coronary artery disease

($4!) in sites other than that already inarcted. 'n addition superimposed ischemic mitral valvere"ur"itation a ventricular aneurysm or a combination o these conditions may be present

urther compromisin" heart unction. The depressed let ventricular unction commonly leads to

impaired peripheral or"an perusion and death in most patients.

4 e& sporadic reports indicate that some patients &ith medically treated postinarction VS+ liveor several years. 4lthou"h many medical advances have been made in the nonsur"ical treatment

o these patients includin" intraaortic balloon counterpulsation ('48$) these methods have

not eliminated the need or sur"ery.

Epidemiology

+upture o the interventricular septum is an uncommon complication o myocardial inarction

(-'). 4lthou"h autopsy studies reveal an 11H incidence o myocardial ree&all rupture ater

-' septal &all peroration is much less common occurrin" at a rate o appro*imately 12H.

Ventricular septal rupture (VS+) occurs in a ;one o necrotic myocardial tissue usually &ithin

the irst 101A days. $linical studies report an avera"e time o 2.< days rom -' to VS+.

9o&ever some data su""est that initial treatment o -' &ith thrombolytics may aect both the

time bet&een inarction and VS+ and the eventual outcome. #arly use o thrombolytic a"entsmay lead to reopenin" o the occluded vessels thereby reducin" the incidence o VS+.

The a"e ran"e o patients &ho sustain a postinarction VS+ is &ide rom AA to 61 years. -en

are aected more commonly than &omen thou"h VS+ is more common in &omen than &ould be predicted on the basis o the prevalence o coronary artery disease ($4!) alone.

Prognosis

Jperative mortality is directly related to the interval bet&een myocardial inarction (-') and

sur"ical repair. 'n a retrospective analysis o A1 patients treated or postinarction VS! Serpytiset al conirmed that &hereas emale se* advanced a"e arterial hypertension anterior &all acute

-' absence o previous acute -' and late arrival at hospital &ere associated &ith a hi"her ris

o mortality rom acute VS! the time rom the onset o 4-' to operation &as the most

important actor determinin" operative mortality and intrahospital survival.DIE

' repair o a postinarction VS+ is perormed 3 &ees or more ater the inarction mortality isappro*imately 20H, i it is perormed beore this time mortality approaches C0H. The most

obvious reason or this is that the "reater the de"ree o myocardial dama"e and hemodynamic

compromise the more ur"ent the need or early intervention.

?ith the use o an early operative approach most studies sho& an overall mortality o less than

2CH. -ortality tends to be lo&er or patients &ith anteriorly located ventricular septal ruptures


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(VS+s) and lo&est or patients &ith apical VS+s. 5or anterior deects mortality ran"es rom

10H to 1CH, or posterior deects mortality ran"es rom 30H to 3CH.

-ore than C0H o deaths occurrin" ater sur"ery or postinarction VS+ are due to cardiacailure. Sudden death is rare and intractable heart ailure can also occur. Jther causes o death

include cerebral embolism. -ost patients &ho survive the hospital period have "ood unctionalstatus &ith the ma>ority allin" into e& Kor 9eart 4ssociation (K94) class ' or ''.D10E

The most important ris actors or death in the early phase are poor hemodynamics andassociated ri"ht ventricular dysunction developin" beore the patient comes to the operatin"

room. The amount and distribution o myocardial necrosis and scarrin" are responsible or both.

+i"ht ventricular dysunction results rom ischemic dama"e or ran inarction o the ri"ht

ventricle and is present &hen stenosis occurs in the ri"ht coronary artery system. The hi"hermortality observed ater repair o deects located ineriorly in the septum is probably related to

the hi"her prevalence o important ri"ht coronary artery stenosis.

The severity and distribution o coronary artery disease ($4!) are also ris actors. Similarly

advanced a"e at operation diabetes and preinarction hypertension are ris actors or death inthe early phase.

+is actors or death in patients &ith postinarction VS+ may be summari;ed as ollo&s7

• osteriorly located VS+s are technically more diicult to repair and are associated &ith

proound ri"ht ventricular dysunction

• The presence o multiple or"an ailure is a poor pro"nostic actor

• The presence o cardio"enic shoc does not bode &ell or the patientLs survival

• 4 shortened interval bet&een inarction and sur"ery usually indicates that the patient is

considered more ill and thereore is at "reater ris or death

'n a retrospective analysis o C2 consecutive patients &ith sur"ically repaired postinarction VS+

over a 30year period (mean ollo&up G.6 M G.G years) Taahashi et al ound that predictors o

30day mortality on univariate analysis included the ollo&in"D11E 7

• +enal insuiciency

• Shoc at sur"ery

• #mer"ency sur"ery

• =o"istic #uroS$J+#

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• Threevessel disease

• Si"niicant let circumle* coronary arterial stenosis

• Si"niicant ri"ht coronary arterial stenosis

• 'ncomplete revasculari;ation

• Sur"ical duration

• $ardiopulmonary bypass time

Jn multivariate analysis only incomplete coronary revasculari;ation &as an independent ris

actor or 30day mortality.D11E

Clinical Presentation:pon auscultation a loud systolic murmur is heard usually &ithin the irst &ee ater an acute

myocardial inarction (-'). This is the most consistent physical indin" o postinarction

ventricular septal rupture (VS+). 8eore the development o the murmur the patient may have

been stable ater the acute -'. $oincident &ith the onset o the murmur the patientLs clinicalcourse under"oes a sudden deterioration &ith the development o con"estive heart ailure ($95)

and oten cardio"enic shoc.

The typical harsh systolic murmur is audible over a lar"e area includin" the let sternal borderand apical area. 't sometimes radiates to the let a*illa thereby mimicin" mitral re"ur"itation

(-+). 4 thrill is palpable in appro*imately C0H o patients.

4lmost C0H o patients have recurrent chest pain. The dierential dia"nosis includes VS+ and

mitral insuiciency secondary to papillary muscle rupture papillary muscle dysunction or letventricular dilatation.

$linical eatures o VS+ may be summari;ed as ollo&s7

• The rupture typically occurs 36 days ater an -'

• VS+ is more liely to occur in the anterior septum than in the posterior septum (


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• !ia"nosis is conirmed &ith the aid o echocardio"raphy and the presence o a letto

ri"ht shunt

• $atheteri;ation results help determine the e*tent o coronary artery disease ($4!)

• J patients treated &ithout sur"ery I0H die

• Sur"ical treatment must be carried out on an emer"ency basis even i the patient is stableD3E

• 4ll VS+s are closed &ith a patch and associated coronary artery bypass "ratin" ($48%)

• Jperative mortality is 101CH or anterior deects and 303CH or posterior deects

Workup

maging studies

Jn plain chest radio"raphs 62H o patients &ith postinarction ventricular septal rupture (VS+)demonstrate let ventricular enlar"ement G6H have pulmonary edema and


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4cute anterior myocardial inarction on #$%.

Catheteri!ation and pressure measurement

=etheart catheteri;ation &ith coronary an"io"raphy is recommended in all stable patients. This procedure is timeconsumin" and carries some de"ree o morbidity in already compromised

patients, accordin"ly "ood >ud"ment is reuired &hen this test is ordered.

4n important dia"nostic test or dierentiatin" VS+ rom mitral valve insuiciency is

catheteri;ation o the ri"ht heart &ith a S&an%an; catheter. 'n the presence o a VS+ o*y"enconcentration bet&een the ri"ht atrium and the pulmonary artery is stepped up. 'n addition a

pulmonary capillary &ed"e pressure tracin" is beneicial or dierentiatin" acute mitralre"ur"itation (-+) rom VS+.

=et and ri"htside pressure measurements help estimate the de"ree o biventricular ailure andare useul in monitorin" the response to perioperative therapy. ?hereas ri"htside ailure is more

common in patients &ith postinarction VS+ letside ailure and reractory pulmonary edema

are more prominent in patients &ith a ruptured papillary muscle. 9o&ever one third o patients&ith postinarction VS+ also have some de"ree o -+ secondary to let ventricular dysunction.

Jnly rarely is VS+ also associated &ith ruptured papillary muscle.

Treatment " #anagement

#edical therapy

'nitiate pharmacolo"ic therapy in an attempt to render the patient hemodynamically stable. The

"oals are to reduce aterload on the heart and to increase or&ard cardiac output.

Vasodilators may be used in an attempt to decrease the lettori"ht shunt associated &ith themechanical deect and thereby increase cardiac output. 'ntravenous ('V) nitro"lycerin can be

used as a vasodilator and may provide improved myocardial blood lo& in patients &ith

si"niicant ischemic cardiac disease.

?hen used alone inotropic a"ents may increase cardiac output, ho&ever &ithout chan"es in theratio o pulmonary to systemic lo& (ptos ratio) they maredly increase let ventricular

&or and myocardial o*y"en consumption. The proound level o cardio"enic shoc in some

patients precludes vasodilator treatment oten necessitatin" vasopressor support.

Vasopressors maredly increase let ventricular &or and myocardial o*y"en consumption. They

also increase systemic aterload and urther increase the ptos ratio thus lo&erin" cardiac

output and "reatly au"mentin" myocardial o*y"en consumption.


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'ntraaortic balloon counterpulsation ('48$) oers the most important means o temporary

hemodynamic support. '48$ reduces let ventricular aterload thus increasin" systemic

cardiac output and decreasin" the ptos ratio. '48$ also acilitates diastolic au"mentation&ith an increase in coronary blood lo& resultin" in an improved o*y"en supply.

'48$ is not a substitute or ur"ent intervention and in patients &ith cardio"enic shoc itshould be ollo&ed by immediate intervention. atients &ith ventricular septal rupture (VS+) do

not die o cardiac ailure, they die as a result o endor"an ailure. Jnly by shortenin" theduration o shoc can the hi"h ris o mortality be prevented.

4chievin" hemodynamic stability beore sur"ery is very beneicial but prolon"ed attempts to

improve the patientLs hemodynamic status can be ha;ardous.D12E

This a""ressive approach oten results in temporary stability o these e*tremely ill patients. 4s arule ho&ever these beneits are brie and patients may deteriorate rapidly. Thereore early

dia"nosis and rapid sur"ical intervention should be planned. Jnly about 101CH o patients can

be treated &ith conservative measures or a period o 2A &ees ater &hich sur"ical treatmentcan be provided at a "reatly reduced ris.

$perati%e therapy

Indications and contraindications

'n vie& o the "rim pro"nosis or medically treated patients the dia"nosis o postinarction VS+ by itsel constitutes an indication or operation. The controversy that once surrounded the timin"

o sur"ical intervention is no lon"er an issue and most sur"eons no& a"ree that early sur"ery is

indicated to minimi;e the ris o mortality and morbidity. The success o sur"ical therapy

depends on prompt medical stabili;ation o the patient and prevention o cardio"enic shoc.

The relative saety o repair 23 &ees or more ater peroration has been established. 8ecause

the ed"es o the deect have become irmer and ibrotic repair is more secure and is easily

accomplished. 4 successul clinical outcome is related to the adeuacy o the closure o the VS+,thereore i possible search or multiple deects both preoperatively and at the time o sur"ery.

Jnly &hen the patient is hemodynamically stable should repair be initially delayed but there

must be a hi"h de"ree o certainty that the patient is in act stable. These patients can suddenly

deteriorate and die. The criteria or a delay in sur"ical treatment include the ollo&in"7

•4deuate cardiac output

• o evidence o cardio"enic shoc

• 4bsence o si"ns and symptoms o con"estive heart ailure ($95) or minimal use o

pressor a"ents to control initial symptoms

• 4bsence o luid retention

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• %ood renal unction

The natural history o the disease is such that e& patients present &ith these si"ns and

symptoms. 'n most patients postinarction VS+ rapidly leads to a &orsenin" o thehemodynamic state &ith cardio"enic shoc mared and intractable symptoms o $95 and luid

retention. 'mmediate sur"ery is usually indicated.D


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• -itral valve replacement

• #*cision o let ventricular aneurysm

$ontroversy surrounds the issue o &hether to perorm $48% in patients under"oin" emer"ency

postinarction ventricular septal repair. Some authors have ound no beneit to $48% in thissettin" and have concluded that cardiac catheteri;ation in ill patients is timeconsumin" and poses a ris o contrast in>ury to the idney. Jthers ho&ever have used a selective approach to

cardiac catheteri;ation.

'n patients &ho probably do not have a history o an"ina or previous myocardial inarction (-')

cardiac catheteri;ation is deerred. $ardiac catheteri;ation indin"s help conirm and uantitatethe presence o a shunt and reveal pulmonary artery pressure and resistance values. The let

ventriculo"ram helps in determinin" the location and number o VS!s deinin" let ventricular

unction and assessin" mitral valve unction. -ost sur"eons perorm bypass in patients &ithVS+ &ith si"niicant improvements in survival.

Jccasionally si"niicant mitral re"ur"itation (-+) may be associated &ith acute VS+

particularly &hen the inarction is posterior. 'n such circumstances the mitral valve must be

replaced. +eplacement is usually best accomplished throu"h the let ventriculotomy by usin"interrupted pled"ed mattress sutures.

?hen a let ventricular aneurysm is associated &ith postinarction VS+ it is e*cised as the

initial step in sur"ical therapy. 4ter repair o the VS+ the aneurysm is "enerally repaired.

Perioperative management

reoperative mana"ement is directed to&ard rapid resuscitation and stabili;ation o the patientand preparation or sur"ery. The "oals are as ollo&s7

• To reduce systemic vascular resistance (thereby decreasin" the lettori"ht shunt)

• To maintain a stable cardiac output and blood pressure

• To maintain coronary artery blood lo&

reoperative treatment o patients &ith postinarction VS+ may be summari;ed as ollo&s7

• Transer patients to an intensive care unit ('$:) or resuscitation

• lace a S&an%an; catheter to assist &ith hemodynamic mana"ement

• !ecrease the systemic vascular resistance and the lettori"ht shunt &ith vasodilators

• -aintain cardiac output and or"an perusion &ith inotropic a"ents

http://emedicine.medscape.com/article/159383-overviewhttp://emedicine.medscape.com/article/159383-overviewhttp://emedicine.medscape.com/article/155618-overviewhttp://emedicine.medscape.com/article/155618-overviewhttp://emedicine.medscape.com/article/351881-overviewhttp://emedicine.medscape.com/article/159383-overviewhttp://emedicine.medscape.com/article/155618-overviewhttp://emedicine.medscape.com/article/351881-overview


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• -aintain coronary artery blood lo&

• :se '48$ to decrease myocardial o*y"en consumption decrease aterload and

increase coronary artery perusion

• :se mechanical ventilation as reuired

• :se echocardio"raphy to help determine the site o septal rupture

• :se cardiac catheteri;ation to help determine the presence o coronary artery disease

($4!)

rinciples associated &ith the evolution o techniues or the closure o postinarction VS+ may

be summari;ed as ollo&s7

• !etermine and understand the anatomy and location o the VS+ and any associated

coronary artery patholo"y

• #*peditiously establish hypothermic total cardiopulmonary bypass and pay attention to

myocardial protection &ith cardiople"ia

• :se a transinarction approach to the VS+ &ith the site o ventriculotomy determined by

the location o the transmural inarction

• 'nspect the papillary muscles and concomitantly replace the mitral valve only i ran

papillary muscle rupture is present

• Trim the let ventricular mar"ins bac to viable muscle

• $onservatively trim the ri"ht ventricular muscle

• $lose the VS+ &ithout tension usin" prosthetic material

• 8uttress the suture line &ith Telon pled"ets.

ercutaneous techniues have been used successully to close some con"enital VS!s. Technicalimprovements in e*perimental devices or closin" intracardiac shunts are bein" made to treat

postinarction VS+ or residual shunts ater primary repair. 4 balloon catheter introduced

percutaneously has been used to abolish the shunt in poorris patients.

atients &ho reuire an intraaortic balloon pump preoperatively appear to beneit rom postoperative support &ith the device or 2AG2 hours. Some o these patients demonstrate a

small persistent or recurrent lettori"ht shunt. 8ecause o the lar"e amount o prosthetic


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material used to repair the septal peroration anticoa"ulation therapy in these patients is

recommended by some sur"eons or a period o

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