John P. Riordan, MD

Objectives:1. To review common implantable medical devices.

2. To appreciate the signs and symptoms associated with malfunctioning of these devices.

3. To gain the necessary familiarity with these devices to both troubleshoot them and speak intelligently with consultants regarding them.

4. Disclaimer?

“Please! Remain in your seats, I beg you! We are not children here, we are scientists!I assure you there is nothing to fear!”

Time to get going?

Conflict of Interests:Traditional hierarchy of

study design

Randomized trials: Double blind RCT with

blinded ascertainment and analysis

Double blind RCT Single blind RCT Unblinded RCT

Observational Studies Cohort Case Control

Descriptive Studies With comparison groups Without comparison groups

Alternative evidence hierarchy

Things I believe Things I believe despite the

available data

Randomized controlled clinical trials that agree with what I believe

Other prospectively collected data

Expert opinion

Randomized controlled clinical trials that don’t agree with what I believe

What you believe that I don’t

Adapted from Bleck TP, BMJ 2000; 321:239

“Hearts and Kidneys are tinker toys! I am talking about the central nervous

system!”

Old stuff:

Ventriculo-peritoneal (VP)

Ventriculo-atrial (VA)

Ventriculo-pleural (VPL)

Lumbar-peritoneal (LP)

New stuff:

Endoscopic Third Ventriculostomy (ETV)

Deep brain stimulators

Shunted patient presents with bulging fontanelle, irritability, vomiting and lethargy….or not

Intra-ventricular Complications (device failure): Ventricular obstruction> distal catheter

occlusion>migration>>>disconnection/breaking (3%) Greatest in infancy

Abdominal Complications: inguinal hernia or hydrocele (higher incidence following

placement in first few months of life) Abdominal CSF pseudocysts (infectious, inflammatory) Ascities

Vascular Complications: VA shunts: higher risk of distal obstruction due to migration,

displacement and thrombosis. Subdural hematoma

C. Di Rocco, Et al, Childs Nerv Syst (2006)

Physical Examination of Patients With Cerebrospinal Fluid Shunts: Is There Useful Information in Pumping the Shunt?

Joseph H. Piatt, Jr 1992;89;470 Pediatrics

Theory: 1 way flow. If depresses easily then outflow is patent. If fills rapidly then inflow is patent.

200 consecutive patients

Poor sensitivity and poor negative predictive value

Conclusion: “Unfortunately, there is no convenient or inexpensive way to make a disposition on the hydrocephalic patient with symptoms suggestive of CSF shunt malfunction. Keeping in mind the morbidity attached to delay in the diagnosis of shunt malfunction, the responsible physician must have a low threshold for ordering definitive brain imaging and must not be deflected by reassurances from pumping the shunt valve.”

Fast MRI What is fast?

What is the benefit?

What are the limitations? Lack of sensitivity in detection of extra-axial and

parenchymal blood products Decreased catheter delineation.

“SEDA-GIVE?”

Slit Ventricle Syndrome

Headaches lasting 10-90 minutes

Normal or small ventricles on imaging studies

Multiple subtypes responding to multiple different management strategies (medical and surgical)

Primarily a disorder of patients shunted in infancy

Infections:Think about it early!

Most (70%) 1 month

85% within 9 months

Typically skin organisms

Often requires removal of shunt

Think about infection in VA shunts with fever

Intra-thecal Analgesia Drug effect:

Narcotics- constipation, sweating, nausea, urinary retention, vomiting, insomnia (common)

Local anesthetics- Ca Channel blockers Alpha 2 agonists- sedation,

hypotension, nausea, dry mouth

NMDA antagonists GABA agonists

Catheter related complications: migration, coiling, obstruction, breakage.

Intrathecal granuloma- beware cord compression

E.V.A.R.

Endoleak: persistent blood flow outside stent graft but inside aneurysmal sac.

20% ( depending on imaging surveillance techniques).

Types I-IV

Endotension: larger aneurysm without leak

www.vascular.co.nz

Left Ventricular Assist Device

I.N.T.E.R.M.A.C.S.: 1092 pt. cohort 6/06-3/09 45% BTT, 42%BTC, 9%DT Overall survival isolated

device 74% Most pulsatile likely

underestimates current survival

Pulsatile devices: more than half require

replacement for infection or malfunction over 2 years

Continuous-flow: smaller, less pump pocket

infection less physiologic due to

continuous flow

“For what we are about to see next, we must enter quietly into the realm of genius.”

Stroke infection Device malfunction Kidney and Liver dysfunction Right heart failure Depression or anxiety High incidence of GI bleeds Suction arrhythmias Hemolysis

Reprinted with the permission of Thoratec Corporation

Complications:

Feeding tubes 101 Clogging:

• The old carbonated beverage trick??• Pancreatic enzymes with bicarbonate??• High Pressure??

Displacement:

• Track can close within hours. • 1-2 weeks to form a track (longer if immunocompromised).• Best to replace same type of tube if possible• X-ray study for confirmation? If so, which type??

Consider a pathway or documentation form!

Gastrostomy Tube-Related Complaints in the Pediatric Emergency Department

Identifying Opportunities for Improvement

Heather Saavedra, MD et alPediatric Emergency Care, Volume 25, Number 11, November 2009.

Major 5% vs. Minor 95%

G: Most common complaint dislodgement 119/159 required replacement 97% success ¾ ED attending Beware of balloon migration into pylorus causing outlet

obstruction Button vs. adjustable length

GJ: Most common complaint malfunction (clogging) 86% replaced by IR Beware aspiration pneumonia due to malpositioning

“Two nasty lookin' switches over there, but I'm not going to be the first”

T.K.A. Most common

replacement

Growing demand

Implant suvival x>90% at 15 years

Early (x<2yrs): Infection, Instability, malalignment, malposition

Late (x>2yrs): polyethylene wear, aseptic loosening, instability

N.Y. Times

“You know, I'm a rather brilliant surgeon. Perhaps I can help you with that hump”….but first, “Get me a

sed rate, CRP, and x-ray…..”

H and P

LAB: WBC? Peripheral leukocyte counts usually not elevated.

Imaging: Plain film 9 A.C.R

A.A.O.S.: clinical practice guideline dx of periprosthetic joint infections: Strong: aspiration for “abnormal” SED AND/OR CRP Inconclusive: We are unable to recommend for or against CT or

MRI as a diagnostic test for periprosthetic joint infection Strong: We recommend against initiating antibiotic treatment

in patients with suspected periprosthetic joint infection until after cultures from the joint have been obtained

Types of dialysis access

AV fistula (biologic materials)- end to side vein to artery anastomosis-need to mature (at least 30 days) higher rate primary failure. More difficult to cannulate Most common?, What

doctor?

Grafts (synthetic conduit)-ready for use earlier polytetrafluoroethylene

Tunneled Catheters-under fluoro tip in RA

Bleeding under a pile of gauze!!!

What type of site?

Is the patient anti-coagulated?

Were they just stuck?

What do you do first, second and finally?

Infections

Systemic Bloodstream Suppurative thrombophlebitis Distant infections- endocarditis, metastatic abscesses

Local Colonization- isolate w/out Exit or insertion site- purulent d/c often gram stain/cx

positive. +/- pain, erythema, tenderness. Port/reservoir- implantable devices, check skin over

reservoir Tunnel infection- x>2cm from entrance site“Treatment of line infections varies by institution and often

depends on the clinical scenario”

Fistula<Graft<CatheterFistula

treat as SBE with 6 weeks of antibiotic therapy

Graft

most require both antibiotic and surgical therapy

Catheter

exit site- w/out systemic sx. And –blood cx.-topical.

If tunnel infection parenteral abx pending tunnel site culture. Failure-new site

Bacteremia-parenteral antibiotics +/- removal based on response to treatment and severity of symptoms

NKF K/DOQI Guidelines 2000

What are the flow problems?

Venous hypertension

High output heart failure- fistulas (uncommon)

Aneurysm/pseudo

Steal

Ischemic Monomelic Neuropathy- early nerve sensori-motor dysfunction without skin or muscle ischemia

Thrombosis higher in grafts early vs. late

The Hemodialysis Reliable Outflow GraftHeRO

FDA 2008 approved as a graft for hemodialysis patients who have exhausted all other access options

At least as good as standard graft

Candidates need: Brachial artery >3mm,

Cardiac EF >20%, SBP >100, absence of infection

Clotting is main complication due to length of tubing

Would it change your thinking if she had one of

these…. Mechanical

phlebitis- difficult to distinguish from infection. Usually present < 10 days from insertion

Withdrawal occlusion/complete occlusion- thrombotic vs. non-thrombotic

“He vould have an enormous schwanzstucker.”

Infection (8-20%) Less common in first time

surgeries Most should have device

removed if significant infection. Select patients with mild infections may be amenable to salvage procedure.

Coated devices Gram +, gram -, anaerobes

Erosion- consider above

Pain- not uncommon for 4-6 weeks following surgery if pain getting worse instead of better see above

MRI often imaging modality of choice

Hossein Sadeghi-Nejad, MD, J Sex Med 2007; 4:296-309

Complications of percutaneous procedures

E. Chen, A. Nemeth , American Journal of Emergency Medicine (2011) 29 802-810.

Introduction:

Vascular: Venous: vena caval filters, venous access

catheters/ports, transvenous hepatic and renal bx., TIPS.

Arterial: uterine artery embolization, ERAR, Chemoembolization.

Non-vascular: Feeding tubes, Biliary drains, nephrostomy/ureteral

stents

Conclusions:

Patients with implantable devices are special

You must include evaluation of the device in your history and physical exam.

Often, specialized device specific testing is required to identify dysfunction.

“Frankenstein Clause”

"What the hell are you doing in the bathroom day and night!? Why don't you get out of there, give someone else a chance!"