The Nuts and Bolts of ICD Therapy E-Book

Tom Kenny

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Serie: Nuts and Bolts Series (Replaced by 5113)
• Sprache: Englisch

Seitenzahl: 335

Veröffentlichungsjahr: 2011

Beschreibung

The number of ICD patients is increasing sharply, yet the number of electrophysiologists--physicians who specialize in the electrical system of the heart--is not increasing as dramatically. The result of this influx is that more and more ICD patients are being treated by physicians and staff with little or no ICD training. There are many fine books on device-based therapy for the heart, but most are written for the experts. Whether you read it from cover-to-cover or use it for reference (or both), it is written primarily with you in mind - for people who are actually involved in the clinical care of these patients. The Nuts and Bolts of ICD Therapy is specifically written for non-cardiologists. This book is written in a lively intelligent and easy to navigate style. It emphasizes real-life clinical practice and practical tips, including illustrations from actual clinical settings. Each chapter concludes with a checklist of key points from each subject ("Nuts and Bolts").

Leseprobe

CONTENTS

Preface

1 Sudden cardiac death

Action potential

Automaticity

Reentry

Types of tachycardia

References

2 The history of ICDs

References

3 The ICD system

4 Indications for ICD implantation

Class I indications

Class IIa

Class IIb

Class III

Indications review

References

5 Implant procedures

Prior to implant

Preparation for implant

The team

Venous access

Lead testing

Device-based testing (DBT)

Defibrillation threshold testing

High DFTs

Concluding the implant procedure

Postoperative care

References

6 Sensing

7 Arrhythmia detection

Defib Only

Defib with Single Tach Zone

Defib with Tach A and Tach B

8 Arrhythmia therapy

High-voltage therapy

Antitachycardia pacing (ATP)

Conclusion

References

9 SVT discrimination

Rate Branch

Interval Stability

Sudden Onset

Morphology Discrimination

Programming SVT discriminators

References

10 Bradycardia pacing

Mode and timing parameters

Episodal pacing

Post-shock pacing

Reference

11 Electrograms

Real-time EGMs

Stored electograms

12 Special features

High-voltage therapy delivery

Pacing therapy

Atrial fibrillation

Patient features

Reference

13 Diagnostics

Tachycardia diagnostics

Bradycardia diagnostics

Shortcuts

Conclusion

14 A systematic guide to ICD follow-up

Interrogation

Real-time measurements

Real-time EGM

Capture testing

Auto Update Morphology Template

High-voltage lead integrity check

Documentation

Programming

Answering the patient’s questions

Conclusion

15 Troubleshooting

ICD does not deliver therapy

ICD delivers inappropriate therapy

Glossary

Index

Preface

When I first started my clinical career, implantable defibrillators were ‘dream machines.’ We could understand in theory how they might work, but the technological obstacles seemed insurmountable. Now, halfway through my career, these devices are not only possible, they are almost commonplace. The technical restrictions that once seemed overwhelming are gone. Today’s ICDs (implantable cardioverter defibrillators) are smaller than some of the pacemakers I once worked with! Despite the fact that a modern ICD is only about one-tenth the size of the original devices pioneered in the 1980s, these new devices last longer and do more.

In the early years of ICD therapy, it was practically a miracle that anyone ever qualified for an ICD. Indications required patients to have survived sudden cardiac death or SCD – not once, but twice! On top of that, patients had to be refractory to drug treatment and yet strong enough to survive an open-chest implantation procedure. Nev-ertheless, increasing numbers of patients received ICDs.

Today, we know that ICDs are not just a treatment of last resort for people with multiple documented episodes of ventricular fibrillation. As ICDs proved their mortality benefits to patients with known potentially lethal arrhythmias, investigators looked at other arrhythmia-rich populations. As a run of large randomized clinical trials has proven, ICDs have been shown to reduce mortality in primary prevention patients, that is, patients with no docu-mented arrhythmias. Expanding ICD indications have saved lives by extending the proven mortality benefits of devices to more and more people. But this has simultaneously caused an interesting problem for the healthcare community: how can we care for this new influx of patients?

That’s why this book was written. More and more clinicians are going to be confronted with managing ICD patients or at least understanding the role of the ICD in their care. Yet medical schools rarely devote much time to the subject of device-based therapy. Most so-called ‘device experts’ got their status through on-the-job training and the help of colleagues who taught them bits and pieces along the way. There are many fine books on device-based therapy for the heart, but many are written for the experts, not the newcomer.

With expanding ICD indications and hundreds of thousands of potential new ICD patients in the coming years, there are bound to be a lot of ‘newcomers’ to the care of the ICD patient!

Whether you’re a rookie in terms of ICD therapy or whether you’re just an occasional player, this book is a good place to start. Whether you read it cover-to-cover or use it for reference (or both), it was written primarily with you in mind. In my own experience, I learned about defibrillation from on-the-job mentoring from knowledgeable colleagues. Mentors are invaluable, and I’m glad to say it’s a bit of a tradition in clinical practice. You may also find support and training opportunities through device manufacturers. I wrote this book to be one part of the solution for helping the busy clinician manage ICD patients.

Even if you’re a veteran of ICD therapy, it is my hope that you’ll find this book contains tips, pointers, facts, and information to which you’ll want to refer. I have worked in various capacities in the field of device-based therapy since before there even were ICDs … and I am still learning about defibrillation. This book is not an in-depth volume for device experts; it’s the nuts and bolts of ICD therapy for people who actually are involved in the clinical care of these patients.

No book is ever the work of one person. I have to thank my editorial team of Jo Ann LeQuang and Alan Yurkevicius for helping me put this manuscript together and my publisher, Blackwell, for ongoing support and encouragement. But most of all I want to thank my family for their continuing understanding for a busy husband and father who just had to take on one more project. For my wife Diane and our children, Christine, Brian, David, Matthew and Kevin, I want to express my love and affection for such generosity.

Tom Kenny

July 20,2005

Austin, Texas

CHAPTER 1

Sudden cardiac death

Sudden cardiac death (SCD) – also known as sudden cardiac arrest (SCA) – has been defined as the unexpected natural death from a cardiac cause within a short time period from the onset of symptoms in a person without any prior condition that would appear fatal.1 SCD has been described as an ‘electrical accident of the heart,’ in that SCD is a complex condition which requires the patient to have certain preexisting conditions and then certain triggering events in order to occur. SCD is responsible for about 400 000 deaths a year in the US.2 Despite our growing knowledge about the mechanisms and markers of this killer disease, SCD remains difficult to treat because the first symptom of SCD is often death.

Many risk factors have been identified for SCD. About 80% of those who suffer SCD have coronary artery disease (CAD), and the incidence of SCD parallels the incidence of CAD (men have CAD and SCD more often than women do, for example). One distinction is that while both CAD and cardiacrelated death increase with age, sudden cardiac death decreases with age versus non sudden cardiac death (NSCD). Older individuals are more likely to experience NSCD than SCD. The peaks of incidence of SCD occur in infants (birth to 6 months) and again between ages 45 and 75 years.1

Several risk factors have been identified for SCD. Some of them are the usual risk factors for any form of heart disease: smoking, inactivity, obesity, advancing age, hypertension, elevated serum cholesterol, and glucose intolerance. Anatomical abnormalities have been associated with SCD. For instance, acute changes in coronary plaque morphology (thrombus or plaque disruption) occur in the majority of cases of SCD cases; about half of all SCD victims have myocardial scars or active coronary lesions.3 For people with advanced heart failure, a non sustained ventricular arrhythmia was found in one study to be an independent predictor of SCD.4 One report bolstered the popular belief that emotional distress can bring on SCD, in that it was found that the incidence of SCD spiked in Los Angeles right after the Northridge earthquake in 1994.5 Other risk factors include the presence of complex ventricular arrhythmias, a previous myocardial infarction (MI) (particularly post-MI patients with ventricular arrhythmias) and compromised left ventricular systolic function. A low left ventricular ejection fraction is a risk factor that affects people with and without CAD. SCD survivors with a left ventricular ejection fraction < 30% have a 30% risk of dying of SCD in the next 3 years, even if they are not inducible in an electrophysiology study. If these patients are inducible to a ventricular arrhythmia despite drugs or empirical amiodarone, the risk can climb to as high as 50%!