When Kids Aren t Wired Right: Pediatric Pacemakers & ICDs

Transcription

1 When Kids Aren t Wired Right: Pediatric Pacemakers & ICDs Maria Markakis Zestos, MD Chief of Anesthesiology, Children s Hospital of MI Associate Professor, Wayne State University

2 No disclosures Michigan February Temperatures Ave High 35 F Ave Low 21 F

3 Goals & Objectives CRMD (cardiac rhythm management devices) Pacemakers Review nomenclature and basic function Indications and terminology ICDs (implantable cardioverter defibrillators) Indications and terminology Review indications for implantation Preoperative Assessment Magnets

4 Permanent pacemaker systems Consist of an impulse generator and leads Sense intrinsic cardiac depolarization by measuring changes in the electrical potential of myocardial cells between the anode (+) and cathode (-) Unipolar leads pulse generator functions as the anode with cathode at the tip of the lead. Needs body contact to work. Bipolar system both anode and cathode are situated on the lead with only a short distance between them. Advantage: less energy required to produce a smaller potential difference. Electrical signals from outside the heart are less likely to be sensed. Reduced susceptibility to electromagnetic interference (EMI)

5 Permanent pacemaker systems Single chamber system Sense intrinsic electrical activity in corresponding chamber. Either inhibit or trigger pacing based on programming. Dual chamber system Sense and pace both the atrium and ventricle. Maintain AV synchrony. Maintain atrial kick which is ~25% of CO. EDV thus SV, and optimize CO Tri-chamber system Resynchronization systems with leads on both RV & LV. Useful in HF therapy and as bridge to transplant. Single V physiology: two epicardial leads on the same ventricle can improve CO.

6 Pacemaker Insertion Transvenous approach Usually implanted via the left subclavian vein. Pulse generator then implanted in the left prepectoral region. Lead survival is superior. May not be possible in some CHD patients. Epicardial approach Usually used in smaller, younger patients. Leads are placed on the epimyocardial surface. Approach is via mini-thoracotomy or subxyphoid incision. Tunneled leads connected to a pulse generator in abdomen. Leads are vulnerable to fracture and dislodgement. Risk of developing increasing pacing thresholds over time. Epicardial approach saves veins and saves vessels.

7 Pediatric Pacemaker Morbidity Greatest risk factor to damage of leads are: Age at time of implant Presence of CHD Children have higher resting and peak HR than adults. This may increase battery utilization and impact longevity of the generator.

8 Internationally recognized code NAPSE (North Am.Society of Pacing & EP) BPEG (British Pacing & EP Group) 5-position code Chamber sensed Chamber paced Response to sensing Rate modulation Multisite pacing Often shortened to first three positions Atrial pacing (AAI) Ventricular pacing (VVI) Dual chamber (DDD) most sophisticated and commonly used mode Pacemaker code

9 General Pacemaker Code T + I = turn on-turn off Ped Anesth 2011; 21:512.

10 Position IV - Rate Modulation Used in those who do not have intact sinus node function. Enables pacer to automatically increase HR to meet metabolic demands. Most common sensors detect bodily accelerations because of motion. Modern PM have crystal built into the can of the PM. Sense vibration. Trigger charge. Settings can be varied for patient and activities. Other sensors can determine minute ventilation via changes in thoracic impedance. Respiratory event such as asthma attack can MV and trigger rate response.

11 Position V Multisite Pacing Refers to either the presence of more than one lead in a single cardiac chamber or biventricular pacing. Cardiac resynchronization therapy Uses simultaneous or near simultaneous pace activation of one or both ventricles to improve ventricular dysynchrony and cardiac function. Decreases paradoxical motion. Has been shown to help 60% of adults.

12 ACC/AHA Classification used to summarize indications Class I: Conditions for which there is evidence and/or general agreement that a given procedure or treatment is useful and effective. Class II: Conditions for which there is conflicting evidence and/or a divergence of opinion about usefulness/efficacy of a procedure or treatment IIa: Weight of evidence/opinion is in favor of usefulness/efficacy. Good literature IIb: Usefulness/efficacy is less well established by evidence/opinion. Some literature IIIc: Opinion Class III: Conditions for which there is evidence and/or general agreement that the procedure /treatment is not useful/effective and in some cases harmful. ACC/AHA/NAPSE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices Summary Article.Gregoratos et al. J Am Coll Cardiol 2002; 40:

13 Indications for Permanent Pacemaker Implantation in Children and Adolescents Main indications for pacing in children: Symptomatic SA node disease (including brady-tachy syndrome and symptomatic bradycardia) Symptomatic 3 rd degree AV block Very low HR in infants

14 Indications for Permanent Pacemaker Implantation in Children and Adolescents Ped Anesth 2011; 21: 512.

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16 Pediatric Implantable Cardioverter- Defibrillator (ICD) Has all the capabilities of a pacemaker plus potential for defibrillation of tacharrythmias. Usually implanted transvenously using a lead that allows sensing, pacing and defibrillation. Very small infants or children with CHD may need surgical implantation.

17 Implantable Cardioverter Defibrillators Measure each cardiac R-R interval Antibradycardia function When R-R interval is too long, most ICDs will start pacing. Antitachycardia function: When enough short R-R intervals are detected, a therapy is started. The device analyzes the presentation. Based on programming, it then chooses antitachycardia pacing or shock. 1 st pace, then overdrive pace, and last shock. Shock = lose myocardial cells. 20% of pediatric ICDs oversense and misfire.

18 Pediatric Sudden Cardiac Death: Cardiac Causes

19 Current Therapies Medication Ablation Devices

20 Indications for ICDs in Pediatrics Implantable Cardioverter Defibrillator Criteria for Primary and Secondary Prevention of Pediatric Sudden Cardiac Death. Charles I. Berul, MD. PACE 2009;32:S67-S70. Recommendations are not age-specific for secondary prevention and are therefore similar to adult guidelines. Few RCT in pediatric and CHD patients that support extrapolation from adult data. Retrospective studies demonstrate efficacy of ICD in these patients.

21 Adult SCD Data Incidence of SCD is 6 to 9 times higher in people with heart failure (HF) than in the general population Incidence of sudden death in specific populations and the annual numbers of sudden deaths in those populations. The benefit of ICDs in selected HF patients has been demonstrated conclusively by several studies. 2 landmark trials MADIT II (Multicenter Automatic Defibrillator Implantation Trial) SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial). Huikuri H, et al. N Engl J Med. 2001;345:

22 Sudden Cardiac Death (SCD) SCD strikes an estimated 325,000 Americans each year ~ 85% of these deaths due to a first-time arrhythmic event. Exponential increase in ICD use Number of ICD implants performed worldwide is expected to continue to rise in the coming years CRT = cardiac resynchronization therapy

23 Secondary Indications for Pediatric ICDs Class I indications: Aborted SCD without reversible cause Not for WPW syndrome with pre-excited AF, myocarditis, electrolyte derangement Sustained VT associated with structural heart disease if not amenable to ablation or surgical resection. Hemodynamically significant sustained VT without reversible cause or potential cure.» Berul et al PACE 2009

24 Primary Indications for ICDs in Pediatrics Charles I. Berul, MD. PACE 2009;32:S67-S70. Less data to support recommendations for pediatric primary prevention. Weigh risks and benefits versus other treatment options and extrapolation from adult data Class IIb evidence: recurrent syncope, VT on B-blockers, Long QT syndrome

25 Indications for Pediatric ICD Placement Ped Anesth :512.

26 Prevention: ICD vs. Drug Therapy NEJM 1997; 337: 1576 Survival with ICD superior to drug therapy (amiodarone).

27 Cardiac Reasons for ICD Implant

28 1 Electrical Accessory Connections: WPW Incidence 1:50 Male 60% diagnosed < 1 y.o. or y.o. ~ 1% SCD Rapid atrial flutter 1:1 conduction Ventricular fibrillation Catheter Ablation Effective therapy with 90% cure

29 Long QTc Syndrome Treatments Normal QT intervals ms ( s) MEDICATION β-blocker (LQT1, LQT2 ) Ca++ blocker PACEMAKER SLOW HEART RATE LQT3 (? LQT2) ICD Aborted Sudden Death ( SCD) VT, VF

30 Hypertrophic Cardiomyopathy Risk factors FHx SCD VT ( younger age) Wall Thickness > 30 mm Diagnosis Difficult Obstruction not predictive for SCD ECG/ECHO non-specific. Not predictive. Can be normal. Restrict sports Treatment: Medications Surgery ICD Heart transplant

31 DEVICE THERAPY LQTc CPVT ARVD TETRALOGY OF FALLOT D-TGA

32 Device Therapy ICDs need to be customprogrammed to meet each patient's requirements for therapy. Strategic planning of therapy is mandatory especially in the young and patients with CHD. When I use my ipod, my ICD shocks me

33 Preoperative Assessment and Preparation

34 Preoperative Evaluation Focus on three main areas: Type of device Dependency on the device for antibradycardia pacing and underlying escape rhythm Device function Make sure the device is working 12% of pacemaker dysfunction is picked up on routine preoperative interrogation. Battery malfunction is the most common cause of device failure ( ICD > pacemaker). Children are at higher risk of lead failure and fracture than adults. Lead failure is the most common cause of inappropriate shocks and ICD complications in children

35 Preoperative Evaluation Indication for CRMD Coexisting CV pathology Pocket generator location Medical ID card: Make, model serial number of device Hx may indicate pacemaker dependency AV nodal ablation, symptomatic bradycardia, syncope. CXR - number, position and integrity of leads

36 Device Interrogation The only reliable method of assessing battery status, lead placement, adequacy of the pacemaker/icd settings Large hospitals, cardiologists interrogate device. In smaller communities, sales rep from company interrogates device. All pacemakers should be routinely interrogated once a year and ICDs every 3 months. ICDs should be interrogated within 30 days of surgery.

37 Navaratnam, Pediatric Anesthesia 2011

38 Electromagnetic Interference (EMI) Radio-frequency waves in the Hz range can cause electromagnetic interference. Causes of EMI: Electrocautery, transthoracic defibrillation, therapeutic radiation, radio-frequency ablation, ECSWL lithotripsy, MRI, nerve stimulators, fasciculation, shivering, large tidal volumes. MRI heats up the metal in the leads and pacer cover. Revo Medtronic PM which is non-magnetic and MRI-compatible. EMI can cause either inappropriate triggering or inhibition of paced output as well as reversion to an asynchronous mode. For ICDs, inappropriate shock may result. Modern devices are less susceptible to EMI because of use of bipolar leads, improved filters and circuit shields which insulate internal electronics.

39 Asynchronous mode ASA task force recommends reprogramming to an asynchronous paced mode in patients who are pacemaker dependent when there is significant risk of EMI. Reprogramming should be preformed before prep and drape so that access to device is not hindered.

40 Magnet Appropriate magnet use in the perioperative period remains controversial. Magnet switches mode. Placing a magnet over center of the pacemaker will cause it to revert to an asynchronous pacing mode (AOO, VOO, or DOO) where no intrinsic cardiac activity is sensed. The pacemaker will pace a the preset magnet rate. 85 bpm (Medtronic) 100 bpm (St Jude) Rate set low so you know it isn't normal. As battery drains, set rate drops. Preset magnet rate may NOT be sufficient to meet the metabolic needs of a pediatric patient.

41 Magnet In emergency situations where time may preclude programming by qualified personnel, a magnet may be placed over the device to revert to asynchronous pacing. Although a magnet should NOT be used routinely to disable ICDs, it CAN be used in emergency situations. Most ICDs will suspend antitachycardia therapy when a magnet is placed over the device.

42 Go Wireless!!

43 2 Ps for every Q make Saw tooth pattern

44 Atrial Flutter 2 Ps for every Q make Saw tooth pattern P-P interval = atrial rate ~300 bpm R-R interval = V-Rate ~187 bpm

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46 Ventricular Tachycardia

47 Is This Normal Device Operation? 47

48 Is This Normal Device Operation? 48

49 Summary CRMD (cardiac rhythm management devices) Pacemakers Review nomenclature and basic function Indications and terminology ICDs (implantable cardioverter defibrillators) Indications and terminology Review indications for implantation Preoperative Assessment Magnets

50 Questions and Thank you Maria Markakis Zestos, MD Chief of Anesthesiology DMC Children s Hospital of Michigan Associate Professor of Anesthesiology Wayne State University mzestos@med.wayne.edu