Intracardiac Devices

Pacemaker Code

A a trial. V

vent 1st letter 2nd letter 3rd letter 4th letter

I = inhibition. D dual Chamber Chamber Response to Program R ■ rate-adaptive paced sensed sensed beat features

Common Pacing Modes

VVI DDD

Magnet

Ventricular pacing on demand w/ single lead in RV. Sensed ventricular beat inhibits V pacing. Used in chronic AF and symptomatic bradycardia. A & V sensing & pacing w/ leads in RA & RV. Sensed A beat inhibits A pacing & triggers V pacing - tracking of intrinsic atrial activity; sensed V beat inhibits V pacing. Used if require A &V pacing or to maintain AV synchrony. Placed over generator A setting to DOO/VOO pacing at fixed rate regardless of intrinsic activity. Use to / ability to capture when output inhibited by intrinsic rhythm. Use when Pt hemodynamically unstable due to bradycardia from inappropriate PPM inhibition or tachycardia that is pacemaker induced.

Indications for Pacing (Grt 2002:106:2145)

AV block

Symptomatic 3° or 2e AVB; ? Asymptomatic 3° or type II 2= AVB HR 40; pauses 3 sec while awake; alternating L and R BBB

Sinus node dysfxn

SB or pauses clearly assoc. w/ sxs or ? in sx Pt w/o clear association Chronotropic incompetence

Acute Ml

See "STEMI"

Tachyarrhythmia

Sx recurrent SVT that can be term, by pacing after failing drugs & ablation Sustained pause-dependent VT;? high-risk Pts w / congenital long QT

Syncope

Carotid sinus hypersensitivity with asystole >3 sees ? Neurocardiogenic syncope w/ prominent cardioinhib. response ? Syncope with bi- or trifascicular block and not likely 2° to other causes

CMP

Sx DCMP (BiV pacing); ? Sx HCMP w/ significant outflow obstruction

PPM Complications

Issue

Manifestation

Description

Failure to pace

Bradycardia

Battery depletion, lead fracture/dislodgment, t pacing threshold due to local tissue rxn/injury. or myopotential sensing — inappropriate inhibition.

Failure to sense

Inappropriate pacing

Lead dislodgment or sensing threshold set too high.

PM-mediated tachycardia

Tachycardia

Seen w/ DDD.V depol. — retrograde A activation — sensed by A lead triggers V pacing etc.

PM syndrome

Palp.. HF

Seen w/Wl. Due to loss of AV synchrony.

Cardiac Resynchronizatioo Therapy (CRT)/Bivent. (BiV) Pacing y\*cc 2005:4«:«1)

• 3 lead pacemaker (RA. RV. coronary sinus); R > S in V, suggests appropriate LV capture

• Goal: enhance "synchronized" RV & LV function (T CO. i remodeling)

• Patient selection: sx HF despite optimal med Rx. LVEF • 35%. ventricular dyssynchrony

(QRS ^ 120 ms • imaging evidence of dyssynchrony). \ sinus rhythm

• Benefits: 1 HF sx. i HF hosp., f survival (ne/a1 2004:350:2140 a 200s;352:1539)

Implantable Cardiac Defibrillators (ICDs) WE}M 2003:349:1836: jacc 2006:48:1064)

• RV lead capable of defibrillation & pacing (• antitachycardia pacing. ATP); - RA lead

• Goal: terminate VT/VF w/ shock or pacing, prevent sudden cardiac death (SCD)

• Patient selection (Ore 2007;115:1170)

2° prevention: survivors ofVF arrest, unstable VT (Avid.ne//vi 1997:337:1576) 1° prevention: LVEF <30-35% (for mo if post-MI or sc9 mos for nonischemic CMP) HCMP. ARVD. Brugada. LQTS. congenital heart or NM disease: if risk factors for SCD

• Benefits: 1 mortality from SCD c/w antiarrhythmics or placebo

• ICD discharge: ✓ device to see if appropriate; r/o ischemia; 6 mos driving prohibition;

if recurrent VT. consider drug Rx (eg.amio ► fJB; omc. jama 2006:295 165) orVT focus ablation. Dual-chamber device may distinguish SVT vs.VT.

Device infection (Ore 2001:104 1029:2003:108:2015)

• Presents as pocket infection (warmth, erythema, tenderness) and/or sepsis wl bacteremia

• Infection in 1/2 of Pts w/ S. oureus bacteremia (even w/o s/s and w/ & TTE/TEE)

• Treatment consists of abx and removal of system

CARDIAC RISK ASSESSMENT FOR NONCARDIAC SURGERY

Goldman Criteria for General Surgery

Risk factor

Points

History Age -70 y

5

Ml within 6 mo

10

Physical exam

Sj or JVD on physical

exam

11

Significant aortic stenosis

3

ECG Rhythm other than sinus rhythm on preop ECG

7

>5 PVCs/min at any time preop

7

General status (any of the following)

3

POi - 60 mmHg, PCO! -50 mmHg.

K 3 mEq/L. HCOj 20 mE^U BUN

• 50 mg/dl, Cr >3 mg/dl

* AST. chronic liver disease, or bedridden due to noncardiac cause

Operation Intra-abdominal, intrathoracic, or aortic surgery

3

Emergency surgery

4

Class

Points

Ml, CHF, VT

Cardiac Death

1

0-5

0.6%

0.2%

II

6-12

3%

1%

III

13-25

11%

2%

IV

>25

12%

39%

(N£JM 1977:297:845. Med On NvtkAm 1987:71:416)

Revised Cardiac Risk Index for General Surgery (RCRI)

Risk factor

Points

High risk surgery (intraperitoneal, intrathoracic, aortic)

1

Ischemic heart disease (prior Ml. 'y ETT, angina, nitrate use. Qw)

1

History of HF

1

History of cerebrovascular disease

1

Insulin therapy for diabetes

1

Preoperative

serum Cr >2 mg/dl

i

Ml, CHF, VF, 3° AVB

Class

# Factors

Derivation Set

Validation Set

1 0

0.5%

0.4%

II 1

1.3%

0.9%

III

2

3.6%

6.6%

IV

3-6

9.1%

11.0%

(Ore 1999:100:1043)

Eagle Criteria for Vascular Surgery

Clinical variables

Stress testing

Angina; 0 waves on ECG Significant ventricular ectopy Diabetes requiring Rx

Pts undergoing vase, surgery have high incidence of CAD. Claudicadon often limits angma. Consider pharmacologic stress test (adeno-MIBI or DSE) in Pts w/ 1-2 variables.

# Variables 0

1-2 ¡=3

Stress test n/.i

© n/a

Event rate 3.1%

3.2% 29.6% 50%

(Annofi 1989:110.843)

(Annofi 1989:110.843)

ACC/AHA Guidelines (6rt 2002:105:1257)

Clinical Markers

Major

Intermediate

Minor

• Decompensated HF

• Significant arrhythmia (eg, high-grade AVB. VT.SVTw/ uncontrolled HR)

• Severe valvular disease

• Compensated/prior HF

• Diabetes mellitus

• Renal insufficiency (Cr >2 mg/dl)

• Rhythm other than sinus

• Low functional capacity

• Uncontrolled HTN

Surgery*Specific Risk

High

Intermediate

Low

• Emergent operation

• Aortic or other major vascular

• Peripheral vascular

• Prolonged w/ Ig fluid shifts or blood loss

• Intraperitoneal/prostate • Superficial

• Intrathoracic • Cataract

• Orthopedic • Breast

Noninvasive Testing Result

High risk

Intermediate risk

Low risk

Ischemia at < 4 METs and

• z5 abnormal leads

• Typical angina

Ischemia at 4-6 METs and No ischemia or at >7

• Isch. 1-3 min after exertion • 1-2 abnormal leads

Figure 1-7 Approach to non-emergent preoperative cardiovascular evaJuaoon

Figure 1-7 Approach to non-emergent preoperative cardiovascular evaJuaoon

Fxnal capacity: 1-4 METS (AOLs). 4-10 METS (flight of scairs heavy housework — light exercise). >10 METS (sports) (Ore 2002:105:1257).

Preoperative and perioperative monitoring and therapy

• If possible, wait >4-6 wks after Ml (even If © ETT or © ETT & revascularized). If no revasc. wait 6 mos before elective surgery.

• Optimize BP. treat s/s HF & any SVT. Critical AS w/ sx needs pre-op AVR or valvuloplasty.

• (S-blockers (JACC 2006.47:2343): use if ischemia. CAD. or major/intermed. clinical markers and undergoing intermedThigh-risk surgery, start >1 wk before (titrate to HR 55) and continue for r-30 d postop (titrate to HR <80); 65-90% i cardiac death & Ml (N£/m 1996:335:1713 4 1999.341 1789)

• Coronary revascularization should be based on standard indications (ACS. refractory angina. Ig territory at risk). No A in mort or postop Ml wI coronary revasc. prior to elective vase, surgery based on perceived cardiac risk {NijM 2004:351 2795).

• Given need for dual antiplatelet Rx after stenting, wait 4-6 wks after bare metal stent and

>12 mos after drug-eluting stent before discontinuing antiplatelet Rx

• ✓ ECG and troponin after surgery to assess for myocardial injury

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