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's and Pacemakers — Transcript

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0:04the objectives for this lecture are as
0:07follows describe indications for a ICD
0:10and pacemaker placement discuss the
0:12various modes of pacing identify
0:14potential complications with pacemakers
0:16and AI CDs during surgery and describe
0:19anesthetic management for patients with
0:21an AI CV or pacemaker this slide is
0:26adapted from the a sa practice advisory
0:28for perioperative management's of
0:29patients with a pacemaker or
0:31defibrillator and describes preoperative
0:33recommendations this slide is adapted
0:37from the a sa practice advisory for
0:39perioperative management of patients
0:41with the pacemaker or defibrillator and
0:42describes intraoperative recommendations
0:46this slide is adapted from the a sa
0:49practice advisory for perioperative
0:50management of patients with the
0:52pacemaker or defibrillator and describes
0:54post-operative recommendations
0:57battery-operated pacing devices were
1:00introduced by CW Lillehei a
1:02cardiothoracic surgeon and Earl Bakken
1:04and electrical technician in 1958 just
1:07four years after the invention of the
1:09transistor in 1960 Wilson Greatbatch an
1:12engineer in Buffalo New York
1:14created the first implantable
1:15battery-operated device in his barn the
1:18natural progression of pacemaker
1:19development led to invention of the
1:21implantable cardioverter-defibrillator
1:22around 1980 by Michael Moore cour of
1:25Baltimore first approved by the US Food
1:28and Drug Administration in 1985
1:30implantation of ICD s required a
1:32thoracotomy a significant operation in a
1:34patient with poor heart function
1:36advances and electronic miniaturization
1:39as well as improvements in battery
1:40technology have led to the development
1:42of very small but electronically
1:44complicated programmable pacing devices
1:49tecnológica ban says like transvenous
1:51lead placement anti tachycardia pacing
1:54capability miniaturization permitting
1:57pectoral pocket placement and multiple
1:59chamber and numerous survival benefits
2:01have led to increases in the uses of
2:03ICDs
2:04these changes in ICD implantation and
2:06indications have two important results
2:08for health care providers first a
2:11pectoral rather than abdominal pocket
2:13ICD web pacing capability might be
2:15mistaken by virtue of pacing spikes on
2:17the surface of an electrocardiogram for
2:19a non ICD pacemaker at many centers
2:23electrocardiograms are obtained from
2:24patients who have pacemakers with the
2:26use of a magnet because some I CDs from
2:29Boston Scientific guidance and CPI can
2:32undergo permanent deactivation of anti
2:34tachycardia therapy with magnetic
2:36placement this mistake could leave a
2:37patient unprotected and possibly result
2:39in death
2:40second pacing functions in an ICD often
2:43respond to external stimuli like
2:45magnetic placement or electromagnetic
2:47interferences differently than a
2:49pacemaker does these issues are
2:51addressed later in this lecture
2:53additionally all ICD is now perform
2:55permanent cardiac pacing so the issues
2:58in the section on pacing will apply to
2:59ICD care as well distinguishing a
3:02conventional pacemaker from an ICD can
3:04be accomplished by examining the right
3:06ventricular lead system on a chest
3:08radiograph a chest x-ray can also be
3:10used to identify the generator
3:12manufacture
3:15pacemaking and defibrillation systems
3:17have a remarkable record for reliability
3:19but they can and do fail myzel and
3:22colleagues reviewed FDA records from
3:24pacemakers and ICD failures either a
3:26death or explantation because of
3:28malfunction other than battery depletion
3:29from the periods of 1990 to 2002 even
3:34though the nature of this reporting
3:35scheme promotes under reporting of
3:36problems for these 12 years 2.25 million
3:39pacemakers were implanted with eight
3:42thousand eight hundred and thirty-four
3:43confirmed and reported malfunctions and
3:4630 deaths for ICD s four hundred and
3:49fifteen thousand seven hundred and
3:50eighty were implanted with eight
3:52thousand four hundred and eighty nine
3:53confirmed malfunctions and 31 deaths
3:56thus every patient with a cardiac
3:58generator should undergo regular
3:59in-office follow-up for appropriately
4:02selected devices telephone checks can be
4:04used to identify battery depletion of
4:06either a pacemaker or ICD or the
4:09detection of tachycardia but telephone
4:11checks cannot ensure adequacy of pacing
4:13capture and sent safety margins at this
4:15time for pacemakers nationally published
4:18guidelines recommend at least a
4:20telephone check every one to three
4:21months depending on implant duration no
4:24such guidelines exist for ICD follow-up
4:27although most ICD manufacturers
4:29recommend follow-up periods not to
4:30exceed four months the complexity of
4:35pacemakers and ICDs as well as a
4:37multitude of programmable parameters
4:39limits a number of generalizations that
4:41can be made about the perioperative care
4:42of a patient with an implanted pulse
4:44generator population ageing continued
4:47enhancements and implantable technology
4:49and new indications for implantation of
4:51cardiac devices continue to drive the
4:53growing number of implants practice
4:56guidelines have been issued by the
4:57American College of Cardiology here
4:59after called the ACC the American Heart
5:01Association the AAA and the heart rhythm
5:04society formerly the North American
5:06Society of pacing and electrophysiology
5:08reviews can also be found in a number of
5:11journals patients with an implant and
5:13cardiac pulse generator often have
5:15significant comorbid disease in addition
5:17to their cardiac rhythm disturbance our
5:19ability to care for these patients
5:21requires attention to both their medical
5:23and psychological problems we don't have
5:25to understand every aspect of the
5:27complex
5:28programming that goes into these devices
5:29but we do need a general understanding
5:31of their pulse generator its function
5:33and it's probable idiosyncrasies in the
5:36operating or procedure room finally not
5:39all electronic generators implanted in
5:40the chest are cardiac devices and
5:42devices resembling cardiac pulse
5:44generators are being implanted at
5:46increasing rates for indications
5:47unrelated to cardiac disease when
5:50implanted in the pectoral position the
5:52usual place for current cardiac
5:53generators these non cardiac devices can
5:56be mistakenly identified as cardiac
5:57generators pulse generator implantation
6:00has been approved by the FDA for pain
6:02control thalmic stimulation to control
6:05Parkinson's disease for an ignorant to
6:07simulate the diaphragm and paralyze
6:09patients and vagus nerve stimulation to
6:12control epilepsy and depression vagus
6:14nerve stimulation is also under
6:16consideration for the treatment of heart
6:17failure and perhaps obesity thus when
6:20evaluating a patient with any pulse
6:22generator one must now determine whether
6:24the pulse generator will be pacing the
6:26heart stimulating the central nervous
6:27system stimulating the spinal cord or
6:30stimulating the vagus nerve as a side
6:33note although the device is commonly
6:34referred to as an automatic implantable
6:36cardioverter-defibrillator or a ICD the
6:39term a ICD is a brand name originally
6:41owned by CPI or cardiac pacemakers
6:44incorporated which was acquired by
6:46guidance Medical Corporation and is now
6:48part of Boston Scientific the term PCD
6:51for programmable
6:52cardioverter-defibrillator belongs to
6:54Medtronic corporation let's look at
6:58pacemakers pacemaker manufacturers
7:01report that more than 2,500 generators
7:03have been manufactured by more than
7:04twenty-six named entities over the past
7:0640 years currently more than 250,000
7:10adults and children in the United States
7:12undergo new pacemaker placement each
7:13year and nearly 2 million patients have
7:16pacemakers today many factors lead to
7:19confusion regarding the behavior of a
7:20device and the perioperative care of a
7:22patient with the device especially since
7:24case reports text books and literature
7:26reviews have not kept pace with
7:27technological developments a pace making
7:31system consists of an impulse generator
7:33and a lead or leads to cure the
7:36electrical impulse to the patient's
7:37heart leads are connected to the heart's
7:39chambers through the vena cava
7:42user transvenous leads or are directly
7:44sewn onto the surface of the heart and
7:46they are called epicardial leads leads
7:48can be unipolar one electro / lead
7:51bipolar two electrodes / lead or
7:54multipolar multiple electrodes and wires
7:57contained within one leaf with
7:58connections in multiple chambers because
8:01two electrodes are required to complete
8:03a circuit the second electrode in a
8:05unipolar configuration will be the metal
8:07generator case use of the case as an
8:09electrode requires that the generator
8:11pocket be devoid of gas and electrical
8:13continuity has reportedly been disrupted
8:15by the use of nitrous oxide pacemakers
8:20with unipolar leads seem to be more
8:21sensitive to the effects of EMI or
8:23electromagnetic interference and these
8:26systems produce a larger spike on an
8:28analogue recorded electrocardiogram most
8:31pacemaker systems pace in bipolar mode
8:34because bipolar pacing usually requires
8:36less energy
8:37bipolar sensing is more resistant to
8:39interference from muscle artifacts or
8:41stray electromagnetic fields frequently
8:44bipolar electrodes can be identified on
8:46the chest x-ray because they will have a
8:48ring electrode 1 to 3 centimeters
8:50proximal to the lead tip note however
8:53that generators what bipolar leads can
8:55be programmed to the unipolar mode for
8:57pacing sensing or both no discussion of
9:02pacemakers can take place without an
9:03understanding of the generic pacemaker
9:05code which has been published by the
9:07NASPE
9:08and British pacing and electrophysiology
9:11group this code called nbg was initially
9:14published in 1983 and was last revised
9:17in February of 2002 and describes the
9:19basic behavior of the pacing device the
9:22first two positions of this code
9:24chambers paste and chamber sense seems
9:26relatively straightforward although
9:28early pacemakers provided only
9:30ventricular support current models can
9:32provide pacing in the atria and
9:33ventricles and these devices can also be
9:36programmed to determine intrinsic
9:37activity in these chambers as well the
9:40code does not describe the array of
9:42diagnostic data that can be accumulated
9:43by these devices probably the most
9:46confusing aspect of the nbg code is the
9:49third position which is the response to
9:51the sensed event most pacemakers are
9:54programmed either to the DD
9:55mode dual-chamber pacing instancing both
9:58triggered and inhibited mode or the vvi
10:01mode for single chamber ventricular
10:03pacing in the inhibited mode two other
10:06modes frequently found are VDD
10:08ventricular pacing with dual chamber
10:11pacing in the triggered and inhibited
10:12mode and DDI dual chamber pacing and
10:16sensing but inhibited mode only this
10:20third position describes the following
10:22behavior dual inhibited or triggered DDD
10:26pacing provides atrioventricular or AV
10:29synchrony in the DDD setting atrial
10:32pacing will take place in the inhibited
10:34mode that is the pacing device will emit
10:37an atrial pulse if no sensed atrial
10:39event takes place within the appropriate
10:41time frame in the DDD or VDD devices
10:45once an atrial event has occurred
10:47whether native or paced the pacing
10:49device will ensure that a ventricular
10:51event follows an inhibited the
10:54appropriate chamber is paced unless
10:55intrinsic electrical activity is
10:57detected during the pacing interval for
10:59the DDI mode AV synchrony is provided
11:02only when the atrium is paste if
11:04intrinsic atrial activity is present no
11:07AV synchrony is provided by the pacing
11:09function in triggered the pacing device
11:12will emit a pulse only if a response to
11:14a sensed event the triggered mode is
11:16used when the device is being tested
11:20the modes V DD and DD I deserve further
11:24comment V DD pacing is used for a
11:27patient with AV nodal dysfunction but
11:29intact an appropriate sinus node
11:31behavior V DD pacing is accomplished
11:34with a single lead that incorporates
11:36atrial sensing electrodes and
11:37ventricular conductors that can both
11:39pace and sense a V DD device has no
11:43atrial pacing capability as a result in
11:46a patient who depends on atrial
11:48contraction to augment cardiac output
11:50events that result in V VI pacing like a
11:53sinus rate below the programmed rate or
11:54battery depletion or asynchronous
11:57ventricular pacing can lead to
11:58deteriorating hemodynamics d di pacing
12:02is indicated for a patient who has a
12:03dual chamber pacing device and also has
12:06episodes of paroxysmal atrial
12:07dysrhythmias d di pacing prevents high
12:11ventricular rates that could result from
12:12attempted tracking of the atrial
12:14arrhythmia and it provides AV synchrony
12:16only when the atrium is paced many ddd
12:20programs will enter the DDI mode on
12:22detection of high atrial rates called
12:24mode switch automatic mode switch or
12:27atrial tachyons depending on the
12:29manufacturer when the mode switches to
12:32DDI perturbations such as a very high
12:35atrial rate or EMI might revert the
12:37pacemaker back to DDD pacing rate
12:42modulation the fourth position also
12:44remains a poorly understood concept
12:46because some patients cannot increase
12:48their heart rate in response to
12:50increased oxygen demand pacemaker
12:52manufacturers have devised a number of
12:53mechanisms to detect patient exercise
12:55such as sensors that detect vibration
12:58respiration and pressure as the sensor
13:00detects exercise it increases the pacing
13:03rate termed sensor indicated rate as the
13:06exercise tapers this sensor indicated
13:08rate returns to the program to lower
13:10rate the sensitivity of these sensors to
13:12their exercise signals and the rates of
13:14change in pacing are programmable
13:16features and current generators
13:18activation of rate response algorithms
13:20resulting in an increased pacing rate in
13:23the operating room whether from vigorous
13:25chest wall skin preparation pressure on
13:27the generator or EMI has led to
13:29inappropriate treatment and patient harm
13:31with the 2002 revision
13:34the nbg the fifth column describes
13:36multi-site pacing functionality it has
13:39been used to describe anti tachycardia
13:41functions but this scheme has been
13:43abandoned and a generic defibrillator
13:45code has been established atrial
13:47multi-site pacing might prevent atrial
13:49fibrillation and ventricular multi-site
13:52pacing is an acceptable means of pacing
13:54patients with dilated cardiomyopathy
13:58there are many indications for permanent
14:00pacing classically anti bradycardia
14:03pacing treats patient with sinus node
14:05disease or improper impulse formation an
14:08AV node disease which is improper
14:10impulse conduction pacing can be used to
14:13reduce the outflow tract obstruction in
14:15hypertrophic obstructive cardiomyopathy
14:16in both adults and children because
14:19paced ventricular conduction takes place
14:21in a left bundle branch pattern meaning
14:23the left ventricular septum depolarizes
14:25after the other segments rather than as
14:27an early systolic event finally in
14:30August of 2001 devices were approved by
14:33the FDA for three chamber pacing right
14:36atrium and both ventricles to treat DCM
14:38this pacing modality can also be called
14:41cardiac resynchronization therapy or
14:43biventricular pacing to accomplish LV
14:47pacing a pacing lead is placed in the
14:49coronary sinus or sewn onto the LV free
14:51wall pacing for hokum and DCM requires
14:55careful attention to pacer programming
14:57to be effective in these patients
14:59the PMS provides a stimulus for
15:01ventricular depolarization and AV
15:03synchrony must be preserved p.m.
15:06inhibition or loss of pacing from native
15:09conduction atrial irregularity
15:11ventricular irregularity the development
15:13of a junctional rhythm or EMI can lead
15:16to deteriorating hemodynamics in these
15:18patients by be pacing might cause
15:21inappropriate lengthening of the QT
15:23interval in susceptible patients and
15:24this lengthening has been reported to be
15:26associated with torsades as a result of
15:29this report a prudent Anessa too should
15:31ensure adequate access to rapid
15:33defibrillation for patients with by be
15:35pacing accomplished without an ICD
15:40despite oft-repeated folklore most
15:43pacemaker manufacturers warn that
15:45magnets were never intended to treat
15:46pacemaker emergencies or prevent the
15:48effects of EMI rather magnet activated
15:52switches were incorporated to produce
15:53pacing behavior that demonstrates
15:55remaining battery life and sometimes
15:57pacing threshold safety factors
15:59placement of a magnet over a generator
16:01might produce no change in pacing
16:03because not all pacemakers switched to a
16:06continuous asynchronous mode when a
16:08magnet is applied moreover not all
16:11models from a given company behave the
16:12same way in some devices magnet behavior
16:15can be altered by programming whereas in
16:18others magnet behavior can be completely
16:19eliminated by programming
16:23for all generators calling the
16:26manufacturer remains the most reliable
16:28method of determining magnet response
16:30and using this response to predict
16:31remaining battery life as battery
16:34voltage Falls the magnet response can be
16:36used to detect the following IFI
16:38intensified follow-up required the
16:41device must be checked frequently
16:42approximately every four weeks for most
16:44models er I elect the replacement
16:48indicator the device is nearing the end
16:50of its useful life and should be
16:51electively replaced
16:52Yoel end of life the device has
16:55insufficient battery power remaining and
16:57should be replaced immediately pre
17:01anesthetic management of a patient with
17:03a pacemaker includes the evaluation and
17:05optimization of coexisting diseases ACC
17:09guidelines suggest that cardiac testing
17:10be dictated by the patient's underlying
17:12disease medications symptomology
17:15interval from last testing and planned
17:17intervention no special laboratory tests
17:20or radiographs are needed for patients
17:22with a conventional pacemaker chest
17:24x-ray is rarely the pick leave problems
17:26and not all devices have radiographic
17:28markings however a patient with a baby
17:31pacemaker or ICD might need a chest film
17:34to document the position of the coronary
17:35sinus lead especially if central line
17:37placement is planned currently there are
17:40no data or guidelines regarding
17:41placement of a central line in the
17:43setting of a coronary sinus lis and
17:45because these leads have no fixation
17:47they might be more easily dislodged than
17:49the standard pacemaker or ICD lead in
17:51fact in early studies spontaneous
17:54dislodgement of the coronary sinus lead
17:56was detected in more than eleven percent
17:57of patients appropriate reprogramming is
18:01the safest way to avoid intra operative
18:02problems especially if mono polar or
18:05Bovie electro surgery will be used many
18:08pacemaker manufacturers stand ready to
18:09assist with this task however
18:12interrogation of any generator with or
18:14without reprogramming requires a medical
18:16prescription and supervision by an
18:18appropriately trained physician hospital
18:20guidelines and policy should reflect the
18:22need for a competent physician to review
18:24and validate any care delivered by a
18:26company representative although no
18:30special monitoring or anaesthetic
18:32technique is required for a patient with
18:33a cardiac generator attention must be
18:36given to a number of
18:37first ECG monitoring of a patient must
18:40include the ability to detect pacing
18:42discharges
18:43currently most ECG monitors in both the
18:46operating room and the intensive care
18:48unit perform digital acquisition and
18:50analysis of electrocardiographic signals
18:53and they are subject to considerable
18:54interference from a variety of sources
18:56in their default settings these monitors
18:59often filter the pacing artifacts and no
19:02pacing spikes will be shown this
19:04filtering must be disabled so that the
19:06monitor will paint pacing spikes onto
19:08the display
19:09even with the filtering disabled however
19:11pacing artifacts do not always appear
19:13atrial signals are weak and current
19:16monitors do a poor job of detecting them
19:18moreover because many of the digital
19:20monitors analyze only one lead for these
19:22signals and then paint on artifacts on
19:25every lead placement of the ECG leads
19:27can markedly affect the detection access
19:29in practice when a patient with known
19:32pacing is monitored sometimes changing
19:34the analysis lead on the monitor will
19:36result in the appearance of pacing
19:38signals unfortunately when the pacemaker
19:40artifact filter is disabled
19:42EMI especially from the use of mono
19:45polar es you can lead to inappropriate
19:47painting of pacing artifacts on the
19:49monitor second patient monitoring must
19:52include the ability to ensure that the
19:54pace electrical activity is converted to
19:56mechanical cicely mechanical Cicely is
19:59best evaluated by pulse oximetry plasma
20:02graphi or arterial pressure waveform
20:04display
20:07third there remains limited published
20:10perioperative experience with
20:12intraoperative IV pacing at this time
20:14these patients often have ejection
20:16fractions of less than 30 percent and
20:18they depend on pacing in both ventricles
20:20to improve their cardiac output loss of
20:23ventricular pacing from any cause like a
20:25VD synchrony atrial fibrillation or
20:27flutter appearance of a junctional
20:29rhythm myocardial ischemia an acid-base
20:32disturbance or a changing in the pacing
20:35threshold can cause an immediate
20:36decrease in cardiac output with the
20:39exception of transesophageal
20:40echocardiography no b2b monitoring of
20:43cardiac output has demonstrated any
20:45utility in detecting loss of by be
20:47pacing behavior patients with hocum
20:50pacing can be dependent on ventricular
20:52pacing to limit LV outflow tract
20:54obstruction fourth some patients might
20:57need an increase pacing rate during the
20:58perioperative period to meet the
21:00increased oxygen demand this subject is
21:02often not addressed pacemaker patients
21:05reportedly experience post-operative
21:07morbidity and mortality frequently and
21:09failure to address tissue oxygen demands
21:11and cardiac output needs might
21:13contribute to this problem this
21:15appropriate equipment must be on hand to
21:17provide backup pacing or defibrillation
21:19or both if needed
21:21cardiac generators although handy
21:23occasionally performs some untoward
21:25maneuver or fail even in the absence of
21:27EMI acceptable but inappropriate
21:30behavior of a pacemaker or ICD can
21:32create an inhospitable situation even a
21:36properly working dual-chamber pacemaker
21:37can produce rnt pacing especially in the
21:40setting of junctional rhythm or
21:42premature ventricular contractions
21:44the medical team caring for the patient
21:46with an implanted cardiac pulse
21:47generator must understand that the
21:49patient has been deemed needy of this
21:51device by a physician who is an expert
21:52in the diagnosis and management of
21:54cardiac rhythm issues very few of us are
21:57qualified to contradict this diagnosis
21:59yet some persists in providing an
22:01anesthetic without appropriate backup
22:02pacing and deeper relation equipment on
22:04hand
22:09mono polar Bo ves you use remains the
22:12principal enter operative issue for
22:14patients with a pacemaker between 1984
22:17and 1997 the FDA was notified of 456
22:21adverse events with pulse generators 255
22:24from electro surgery and a significant
22:26number of device failures a mono polar
22:29ESU is more likely to cause problems
22:31than a bipolar ESU and pacemakers with a
22:34unipolar electrode configuration are
22:36more sensitive to EMI than those with
22:38bipolar configurations the most common
22:41effect of an e su on pacing function is
22:44ventricular / sensing which causes
22:46pacing inhibition sometimes the
22:48generator detects significant EMI and
22:50begins pacing asynchronously at the
22:52programmed lower rate this behavior is
22:55called noise reversion mode pacing even
22:58though the pacemaker does not actually
22:59change modes noise reversion is not
23:02present in some I CDs and is
23:04programmable in others if a mono polar
23:09ESU is to be used the electrosurgical
23:11current return pad often misidentified
23:13as a grounding pad must be placed to
23:16ensure that the e su current path does
23:18not cross the pacemaking system some
23:21authors recommend placement of this pad
23:23on the shoulder for head and neck
23:24procedures or on the distal part of the
23:26arm with a sterile drape of the wire for
23:28breast and axillary procedures
23:32procedures using only a mono polar ESU
23:35or with special emi pacing ramifications
23:38include the following lithotripsy
23:40transurethral resection and uterine
23:43hysteroscopy magnetic resonance imaging
23:45electroconvulsive therapy nerve
23:48simulator testing or therapy or
23:50succinylcholine or etomidate use most
23:54monitors manufactured since 2005 have
23:56much improved capability to detect and
23:58display pacing artifacts although they
24:00still filter these high-frequency
24:01signals in their default setup mode
24:05pacemaker failure has three causes
24:07generator failure lead failure or
24:10failure of capture generator failure is
24:13rare and a device that has previously
24:15been evaluated and not near the end of
24:17useful battery life unless the generator
24:19or leads is struck directly by the ESU
24:22bleep failure also unusual but reported
24:25during patient repositioning can result
24:27in under sensing / sensing or failure to
24:30deliver sufficient energy to the
24:31myocardium to produce depolarization
24:34term loss of capture myocardial changes
24:37that lengthen the refractory period or
24:39increasing energy requirements for
24:41depolarization can result from
24:42myocardial ischemia or infarction
24:44acid-base disturbance electrolyte
24:47abnormalities or abnormal
24:49anti-arrhythmic drug levels the response
24:53to pacemaker failure depends on the
24:55clinical situation a patient with a
24:57perfusing rhythm and stable vital signs
25:00can be observed while a plan is made to
25:01correct the problem for a patient with
25:04inadequate profusion the following steps
25:06can be attempted
25:07while cardiopulmonary resuscitation is
25:09in progress when appropriate one a
25:11magnet can be applied if the pacemaker
25:13is known to revert to an asynchronous
25:15mode which will also eliminate sensing
25:17behavior in these devices for many of
25:20the st. Jude auto capture devices with
25:22magnet mode enabled magnet application
25:24might increase pacing amplitude and
25:26restore capture devices from ela medical
25:30typically increase their pacing
25:31amplitude when a magnet is applied some
25:34pacemakers perform threshold margin
25:36testing upon magnet placement which can
25:38further reduce pacing to temporary
25:41pacing can be initiated and it can be
25:42transfer assic transcutaneous
25:44transvenous or transesophageal
25:47transesophageal atrial pacing requires a
25:50functional atrium and AV node for
25:52ventricular activation so it is
25:54contraindicated in patients with atrial
25:55fibrillation or flutter it is also
25:58generally contraindicated in the
26:00presence of a permanent pacemaker or ICD
26:02in the setting of external pacing the
26:05electrocardiogram can be misinterpreted
26:06because the pacemaker artifacts are
26:08large in comparison to the QRS complexes
26:12successful ventricular pacing has been
26:14reported with transesophageal pacemakers
26:16but it remains unreliable and produces
26:18inferior hemodynamics when compared with
26:20atrial pacing note that any external
26:23pacing might further inhibit pacemaker
26:25output at energies that will not produce
26:27myocardial capture 3 sympathy mimetic
26:30drugs can decrease the polarization
26:32threshold or increase chrono tropa city
26:35or both
26:36epinephrine 0.5 to 1 mic per minute or
26:39dopamine 5 to 20 mics per kilo per
26:42minute should be considered
26:43isoproterenol 0.5 mics per minute is
26:47often recommended but not widely
26:48available and is complicated by
26:50hypotension antimuscarinic drugs like
26:53atropine and glycol pie relate might be
26:55helpful for causes of myocardial
26:58ischemia should be sought and corrected
27:00myocardial ischemia can substantially
27:02increase the energy required for
27:04ventricular capture 5 disturbances and
27:07electrolyte balance anti-arrhythmic drug
27:09levels and acid-base equilibrium should
27:11be investigated and corrected potassium
27:14calcium and magnesium abnormalities can
27:17raise depolarization thresholds in
27:19addition potassium flux ionized calcium
27:22levels and acid-base equilibrium can be
27:25affected by hyperventilation and
27:27hypoventilation 6 if none of the
27:30measures just presented succeed
27:31consideration should be given to the
27:33placement of an epicardial lead by the
27:35surgical staff a pacemaker that was
27:39reprogrammed for the perioperative
27:40period should be reset appropriately for
27:43non reprogrammed devices most
27:45manufacturers recommend interrogation to
27:47ensure proper functioning and acceptable
27:49remaining battery life if any electro
27:51surgery was used the ACC guidelines now
27:54recommend a post procedure interrogation
27:57consideration should be given to
27:58increasing the lower paced rate in a
28:00chrono tropically incompetent patient if
28:02increase cardiac output will benefit the
28:04patient during convalescence the
28:08development of an implantable
28:10battery-powered device able to deliver
28:12sufficient energy to terminate v-tach or
28:14ventricular fibrillation represents a
28:16major medical breakthrough for patients
28:18with a history of ventricular
28:19tachyrhythmia these devices reduce
28:22deaths in the setting of malignant
28:23ventricular tachyrhythmia x' and they
28:25clearly remain superior to
28:27anti-arrhythmic drug therapy initially
28:30approved by the fda in 1985 more than
28:3260,000 devices will be implanted in the
28:34United States this year an industry
28:36sources report that more than 250,000
28:39patients have these devices today
28:41furthermore results from the sudden
28:43cardiac death heart failure trial have
28:45led to a significant increase in the
28:47number of patients for whom ICD therapy
28:49is
28:49indicated a considerable number of
28:52technological visas have been applied
28:53since the first ICD was placed including
28:56substantial miniaturization as well as
28:58battery improvements that now permit
29:00permanent pacing with these devices thus
29:03one could easily confuse a pectoral ICD
29:05for a pacemaker like pacemakers I see
29:08these have a four place to generic code
29:10to indicate lead placement and function
29:12the most robust form of identification
29:14called the label form experience the
29:17fourth character into its component
29:18generic pacemaker code newer icds since
29:231993 have many programmable features but
29:26essentially they measure each cardiac
29:28Arta are interval and categorize the
29:30rate as normal too fast or too slow when
29:34the device detects a sufficient number
29:35of short r2r intervals within a certain
29:38period it will begin an anti tachycardia
29:40event the internal computer will choose
29:43ATP or shock depending on the
29:45manifestation and device programming if
29:48shock is chosen an internal capacitor is
29:50charged charging time is dependent on
29:53the desired output and it can be from
29:55six to fifteen seconds for a maximum
29:57shock charging time is lengthened by low
29:59battery voltage time from last charge
30:01and low temperature most IC these can be
30:06programmed to reconfirm v-tach or v-fib
30:09after charging to prevent inappropriate
30:11shock therapy some IC DS can be
30:14programmed to begin ATP immediately on
30:16initiating a charge cycle typically I
30:19see these deliver six to eighteen shocks
30:21per event once the shock is delivered no
30:24further ATP will take place despite
30:27considerable improvement in the
30:28detection of ventricular dysrhythmias
30:29more than 10% of shocks are for rhythms
30:32other than v-tach or v-fib
30:34super ventricular tachycardia remains
30:36the most common etiology of
30:38inappropriate shock therapy and causes
30:40of inappropriate shock have been
30:41reviewed elsewhere programmable features
30:44and current IC DS to differentiate
30:46v-tach from a tachycardia of super
30:48ventricular origin include the following
30:50onset criteria
30:52stability criteria QRS with criteria the
30:56intelligence and the morphology waveform
30:59analysis
31:01an ICD with antibiotic Ardea Therapy
31:05capability will begin pacing when the
31:07RTR interval is too long
31:09in July of 1997 the FDA approved devices
31:12with sophisticated dual chamber pacing
31:14modes and rate response behavior for ICD
31:17patients who need permanent pacing which
31:19is about 20% of ICD patients because of
31:22the David study which suggested that the
31:25DDD pacing in a patient with a clear
31:27need for a dual chamber pacing decreases
31:29survival when compared with a single
31:31chamber device placement many
31:33electrophysiologists our programming
31:34long AV delays in these patients to
31:36limit ventricular pacing as noted
31:39previously however long a V delays can
31:42lead to our on T pacing in addition many
31:45ICD manufacturers have designed
31:47algorithms to limit ventricular pacing
31:49some of these algorithms allow dropped
31:51QRS events which can resemble a
31:54second-degree mobitz to block or
31:55malfunction of the pacing system
31:59initially I see these were placed for
32:01hemodynamically significant v-tach or
32:03v-fib newer indications associated with
32:06sudden death include patients awaiting
32:08heart transplantation and those with
32:10long QT syndrome Brugada syndrome and a
32:13red magenta RB dysplasia studies suggest
32:17that icds can be placed prophylactically
32:19to prevent sudden death in young
32:20patients with hypertrophic
32:21cardiomyopathy as well as in post
32:24myocardial infarction patients with an
32:26ejection fraction less than 30 percent
32:27but they are no benefit after coronary
32:30artery bypass grafting like pacemakers
32:34magnet behavior and ICDs can be altered
32:37by programming most devices will suspend
32:40tacky dysrhythmia detection and
32:42therefore therapy when a magnet is
32:44appropriately placed to activate the
32:45magnet switch some devices from ng on
32:48Boston Scientific CPI guidance
32:52pacesetter
32:53st. Jude medical or venture Tech's can
32:56be programmed to ignore magnet placement
32:58and some guidance icds have their magnet
33:00function permanently disabled because of
33:02a magnet switch issue depending on
33:05programming
33:05anteye tachycardia therapy and some
33:07Boston Scientific guided medical and CPI
33:10devices can be permanently disabled by
33:12magnet placement for 30 seconds and as
33:15earlier some patients have been
33:16discovered with their ICD anti
33:18tachycardia therapy unintentionally
33:20disabled in boston scientific guidance
33:25and CPI devices if the magnet mode is
33:28enabled and the ICD is enabled for anti
33:31tachycardia therapy the ICD will emit
33:33beep synchronized to our waves to
33:35signify adequate placement of the magnet
33:37and suspension of the tachyarrhythmia
33:39detection hence disabling of the therapy
33:42if the ICD emits a constant tone anti
33:45tachycardia therapy has been programmed
33:47to off regardless of magnet placement
33:50depending on programming ICD is from
33:53boston scientific guidance medical and
33:55CPI can toggle between activated and
33:57inactivated states with 30 seconds of
33:59magnet application thus to re-enable
34:02therapy the magnet must be removed and
34:05then replaced until the constant tone
34:07reverts to beep synchronized to our
34:08waves subsequent removal of the magnet
34:11then returns the anti tachycardia
34:13therapy to the enabled state any Boston
34:16Scientific Gaiden or CPI device that
34:19emits either beeps or constant tones
34:21while a magnet is in place will have its
34:23anti tachycardia therapy disabled during
34:25the magnet session in general magnets
34:30will not affect ICD anti bradycardia
34:33pacing modes or rates enter medics
34:36devices transiently change the pacing
34:38rate to reflect battery voltage again
34:41interrogating the device and calling the
34:43manufacturer remain the most reliable
34:45method for determining magnet response
34:48in addition to evaluating and optimizing
34:52any comorbid disease and ICD patients it
34:54is often suggested that every ICD should
34:57undergo preoperative interrogation these
34:59devices store considerable data
35:01regarding the occurrence of this read
35:03Mia's because ATP is well tolerated most
35:06patients are not aware of this
35:07intervention for any patients scheduled
35:10to undergo an elective procedure the
35:12onset of a new dysrhythmia probably
35:14warrants investigation of the problem
35:16before the procedure here is a case
35:18study where unexpected ventricular
35:20tachycardia with anti tachycardia pacing
35:22was found during a visit from a surgeon
35:24requesting cardiac clearance a 65
35:27year-old woman with a history of beat
35:29had undergone implantation of a
35:30Medtronic single-chamber defibrillator
35:32about eight months previously she had
35:35not had any dizziness or syncopal
35:37episode since the placement
35:39interrogation of her device in the
35:40preoperative center revealed vve v VI
35:43programing along with an episode of
35:45tachycardia at 150 to 160 beats per
35:48minute that was detected by the ICD s
35:51v-tach
35:51the ICD delivered a 6-feet burst of anti
35:54tachycardia pacing at 182 beats per
35:57minute which converted the tachycardia
35:59back to sinus rhythm no backup pacing
36:02was needed after the v-tach was
36:03terminated this device was set to detect
36:06v-tach at 16 consecutive ventricular
36:08events with a rate between 146 and 200
36:11per minute and to deliver anti
36:13tachycardia pacing at 84% of the last
36:16RTR interval the surgery was
36:19consequently postponed pending further
36:20evaluation the determination of the need
36:25for elective replacement of an ICD
36:27because of battery depletion is more
36:29complicated than with pacemakers because
36:32some ICDs can have multiple battery
36:34cells predicting battery depletion based
36:36on battery voltage is difficult in
36:38general however the manufacturer should
36:40be consulted for any device with a
36:42charging time in excess of 12 seconds
36:45most ICD should have their anti
36:47tachycardia therapy disabled before the
36:49use of any device that causes EMI the
36:52use of a mono polar es you can produce
36:54inappropriate shocks many icds have no
36:57noise reversion behavior so es un deuce
37:00ventricular / sensing might lead to non
37:02pacing in a patient who is dependent on
37:04the ICD for pacing at this time no
37:10special monitoring because of the ICD is
37:12required for a patient with an ICD
37:16electrocardiographic monitoring and the
37:17ability to deliver external
37:19cardioversion or defibrillation must be
37:21present during the time of ICD
37:23disablement should cardioversion or
37:26defibrillation be needed the
37:27defibrillator pads should be placed so
37:29that they avoid the pulse generator to
37:30the greatest extent possible
37:32nevertheless one should remember that
37:34the patient not the ICD is being treated
37:36the other recommendations that we
37:39discussed for the intraoperative
37:40management of pacemakers apply here as
37:42well
37:44no special anesthetic techniques have
37:46been championed for patients with an ICD
37:49most of these patients will have
37:50severely depressed systolic function
37:52dilated ventricular cavities and
37:54significant valvular regurgitation
37:57thus the anesthetic of choice should be
37:59dictated by the underlying physiological
38:01Arrangements that are present
38:03conflicting data have been published
38:04regarding the choice of an anesthetic
38:06agent or agents and changes in
38:08defibrillation threshold in 1993 Gill
38:11and co-workers examine defibrillation
38:13threshold and dogs and concluded that
38:15neither halothane nor isoflurane changed
38:18the DFT and open chest defibrillation
38:20when compared with pentobarbital and
38:22fusion however whine Burum and
38:25associates evaluated the defibrillation
38:27threshold in humans during ICD
38:29implantation and found that halothane
38:31isoflurane and fentanyl increased the
38:33DFT even with these increases the
38:36increased dfts were still substantially
38:38lower than the maximum energy generally
38:40available in ICDs
38:42and these increases would not have been
38:44noted under the usual testing conditions
38:45as a post anesthesia evaluation the ICD
38:51must be rien tera gated and re-enabled
38:53and deaths from failure to re-enable an
38:55ICD have been reported all recorded
38:58event should be reviewed encounter
39:00should be cleared the pacing parameters
39:02must be checked and reprogrammed as
39:04necessary in conclusion electronic
39:09miniaturization has permitted the design
39:11and the use of sophisticated electronics
39:13and patients who have need for
39:14artificial pacing or automated
39:16cardioversion defibrillation of their
39:18heart these devices are no longer
39:21confined to merely keeping the heart
39:22beating between a minimum and maximum
39:24rate they are now being used as therapy
39:26to improve a failing heart both aging of
39:29the population and our ability to care
39:31for a patient with increasingly complex
39:33disease suggest that we will be caring
39:35for many more patients with these
39:36devices and we must be prepared for this
39:38situation safe and efficient clinical
39:41management of these patients depends on
39:43our understanding of implantable systems
39:45there are indications of use and the
39:47perioperative needs that they create
39:48this slide is a reference a pulse
39:51generator companies for you companies
39:53that are bolded market implantable
39:55cardioverter to
39:56or bleeders
40:04you

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