Case Study: Palpitations Following Pacemaker Implantation and AVJ Ablation

A 70 year old woman underwent a DDDR pacemaker implantation (Medtronic Versa DR) and AV junction ablation for chronic atrial fibrillation refractory to medical therapy six months after she presented to the pacemaker clinic.  She returned complaining of intermittent palpitations, usually worse at night.  An interrogation of her permanent pacemaker demonstrated the following:

(Click image to enlarge)

Her P waves are interrogated and appeared to be of a sufficient amplitude of 1.4-2.0 mV:

(Click image to enlarge)

Likewise, her Cardiac Compass plot of the duration of atrial fibrillation each day showed the following:

(Click image to enlarge)

Upon seeing these data, it was felt the patient may be undersensing her fibrillatory P waves (formally known as F waves). To improve her pacemaker's atrial sensitivity, the sensitivity threshold was changed from 0.5 mV (her initial setting) to a more sensitive setting of 0.25 mV.  Here is how the device responded to this change in sensitivity:

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Even a more sensitive setting of 0.18 mV showed similar results:

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Here's her sensing at the original (less sensitive) setting of 0.5 mV. Unfortunately, occassional atrial pacing was still seen:

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Programming to an even less sensitive setting of 0.7 mV appeared to paradoxically have improved sensing of her atrial fibrillation:

(Click image to enlarge)

How do we explain what is happening here?   Would you revise her right atrial lead?  If not, what atrial sensitivity setting would you use for this patient and why?

-Wes

PS:  Give it your best shot to see if you can explain what is going on with this patient's atrial pacing sensitivity setting.  When you finally give up and want the answer to what's going on: consider clicking here.

Case Study: An Unusual Catheter Course to the Right Atrium

Recently, our laboratory was performing a catheter ablation of paroxysmal atrial fibrillation in a patient with a permanent pacemaker previously implanted from the left axillary venous approach.  The fellow placed a decapolar catheter from the left femoral vein, but it took an unusual course to the right atrium.    Attempts to place the catheter via a more typical course could not be achieved.

Here are the RAO and LAO fluoroscopic images he saw (labeled for your convenience):

RAO Fluoroscopic Image (click to enlarge)

LAO Fluoroscopic Image (click to enlarge)

At first, the fellow thought the catheter was extravascular was the catheter passed behind the heart, but continued advancement resulted in the catheter entering the right atrium.

Here's the LAO Cineangiogram of the finding that helped us identify the cause:

Here's the RAO image of the same shot:

What is this?  What happened next?

-Wes

PS:  If you can't wait, here's a link to a pretty illustration of the anatomy.  Note the hepatic drainage to the right atrium is separate from the drainage of the IVC in this anomaly.  Here's another link to factoids from the radiology literature regarding this interesting finding.

Case Study: Mitral Annular Left Atrial Flutter

Sometimes what we do is just cool.

Cardiac electrophysiology has amazing technology at its disposal. One of these is three dimensional mapping. While three-dimensional mapping is not always required to perform catheter ablation, it can be invaluable when mapping and ablating forms of post-surgical atypical atrial flutter. The video below shows one such case we performed with the three-dimensional mapping system from Endocardial Solutions.

This system uses an X/Y/Z coordinate system created by referencing impedance changes that occur between paired electrodes placed on the patient's chest. Moving a single mapping catheter inside the left atrium during the patient's tachycardia permits localization of both the ablation catheter and the signal recorded.  An "activation map" from approximately 200 different points (the tiny white dots) that we collected in patient's left atrium is displayed below. The low amplitude signals (less than 0.5 mV) were colored grey. The map had the area of the mitral valve "cut away" using software so the endocardial surface could be better seen.

In this map, endocardial activation proceeds in a clockwise fashion and slows ever-so-slightly in the posterolateral mitral annulus near the blue dot. A single radiofrequency energy application at this location immediately terminated the patient's incessant left atrial flutter.



I love my job.

-Wes

Case Study: A Case of Recurrent Ventricular Tachycardia

The following is a case study intended for folks who look at defibrillator recordings.  If you find it interesting, great.  If you have no clue what is shown here, don't feel bad, just move on to another blog post.  I just thought I'd put this up as an unknown for those interested in phenomena encountered in a busy device clinic.

It was a case seen in our clinic: a nice man in his 50's had received a single chamber ICD for recurrent ventricular tachycardia and ventricular fibrillation and called because he had received several shocks from this device.  Interrogation of the device showed normal sensing, lead impedance and capture threshold.  Interrogation of his device demonstrated multiple VT therapies and untreated events recorded by his device. 

An example of several of the recorded interval plots (Event 202 and 203) as well has one example of the electrograms (and therapies delivered) recorded during episode 202 are shown below.  56 similar events were recorded since his last device interrogation, all with a similar pattern:



Episode 202 RR Interval Plot (Click to enlarge) 

Event 203 RR Interval Plot

Event 202's Recorded Electrograms and Intervals (Click image to enlarge)
 

Any thoughts about why this man might be having VT?

-Wes

When Placing a Pacemaker, You Know You're on the Wrong Side When

... your wires look like this: 

AP fluoroscopic view


... and the venogram looks like this: 

Results of a left subclavian venogram


-Wes

EKG Du Jour 32: The Misfiring Pacemaker

A dual chamber pacemaker was implanted the prior day by a local surgeon in the operating room.  The next morning, an EKG is obtained that showed the following:

Click to enlarge

You checked the CXR and all leads appeared to be in the proper location. 

Does the patient have to go back to the operating room?  Why or why not?

-Wes

Case Study: Um, A Post-op Chest X-ray

Radiologist: "Um, doctor, there's something funny on your patient's post-operative chest x-ray:"



Post -operative Chest X-ray
(Click to enlarge)

(Remember, you never want to hear the word "Um.")

What did the radiologist see?

-Wes

Case Study: The "Simple" ICD Revision

The following is an actual cardiac electrophysiology case study offered with the patient's permission. It's technical and contains an image that might turn some folks' stomachs, so for those who are a bit squeemish or just ate a meal: consider yourself warned and feel free to pass on this post. For the rest of you who remain interested and don't mind medical images, good luck.

It was supposed to be a simple ICD revision.

A prior abdominal ICD has been implanted in 1995. As was the norm of the day, the large ICD pulse generator was implanted in the left upper quadrant of the abdomen and an connected to an old Guidant Endotak Model 0074 lead that was implanted via the left subclavian vein and then tunneled down to the abdominal pocket. The device served the patient well for many years until its battery depleted in 2003. At that time, a new, smaller ICD with an appropriate header  replaced the old abdominal device and because the defibrillator lead worked well, the smaller ICD pulse generator was left in the abdominal pocket.

Years passed and the patient followed reliably in the Device Clinic for his routine defibrillator checks. While the lead impedance and capture thresholds remained normal, about a year ago intermittent periods of noise with non-physiologic short RR intervals suggestive of possible impending lead fracture began to appear on the patient's device checks. Because the patient was not pacemaker dependent nor near the time when his existing ICD battery would have to be replaced again, it was elected to wait until his battery reached it's elective replacement indicator before revising his system. When that time came, a new defibrillator lead could be implanted and connected to a more conventional VVIR ICD pulse generator implanted in the upper chest area (the patient has chronic atrial fibrillation). The old pulse generator could then be removed from his abdomen and the old lead capped and left in place.

So the day came for surgery. The patient felt fine: no fever, chills or other unusual symptoms pre-operatively. A venogram performed immediately before the procedure disclosed a patent left axillary and subclavian veins, so it was decided to first proceed with the new ICD implant on the same side as the site where his first defibrillator was implanted followed by removal of the old ICD pulse generator from the abdomen.  Pre-operative antibiotics were administered. To make a long story quite a bit shorter, the new single-chamber ICD implanted via the left axillary approach was performed without a hitch. A dressing was applied to the wound and preparations made to explant the abdominal pulse generator.

The lower abdominal area was similarly prepped and draped. Local anesthetic was infiltrated over the prior abdominal scan and an incision made at this location. Using electrocautery dissection, the incision was carried to the pulse generator capsule which appeared to be quite thick, but uninflammed. The fibrous capsule surrounding the pulse generator was then opened. What was found was startling to all.

Inside the pulse generator pocket was the device and lead system surrounded in a thick fluid that looked, for lack of a better way to describe it, like wet, brown mud. There was no odor. The device was extracted from the pocket after the suture holding the header of the device to the pocket wall was cut. A portion of the lead was also cut removed with the device. A picture of the removed device is shown here:

Soooo. What now?

Imagine you are the surgeon with this device in your hands. You have another case after this one. You struggle to find where this situation falls within our clinical "guidelines" for care and find very little. You aren't sure what you're seeing, but only know that this "chocolate-coated" ICD pulse generator is not the norm. (Usually they are nice and clean without debris.)

Ideas?

-Wes

A Chest X-Ray You Don't See Everyday

... unless, of course, you're a cardiac electrophysiologist:

An anterior-posterior (AP) and lateral (LAT) chest radiograph
(Click image to enlarge)

-Wes

PS: Answer here.

The Radiographic Appearance of A Ubiquitous Medical Device

Fluoroscopic image

So, what is it?

-Wes

When Patients Make Their Own Diagnosis

"Doctor, I've been taking my vitals signs and they've been very stable, but recently I've noted I just have no "get-up-and-go." I feel short of breath climbing stairs now. Any idea what might be going on? Here's what I've recorded:"

The patient's self-recorded vital signs
(Click to enlarge)

So, what's the diagnosis?
(Hint: remember who the patient came to see...)

-Wes

How To Simplify Consents

He arrived at the emergency room diaphoretic, hypotensive, and with substernal chest pressure.  The patient was brought immediately to an emergency room care area and a stat EKG disclosed classic ST segment elevation in the inferior leads.  The cath lab team was immediately summoned as the ER team worked to stabilize the patient.  Within minutes, the attending cardiologist was on the scene, reviewed the EKG, examined the patient, and explained to the hoardes of family members with the patient what was taking place.  In the interest of being expeditious with his consent process as the team was arriving to take the patient to the cath lab, the attending said:

"There is a 1% risk that anything bad that you can think of could happen with this procedure.  If you'd like me to detail those things, I can."

The patient didn't want to hear, and off to the cath lab they went to open the patient's occluded right coronary artery to great relief of the patient and family.

Later, in follow-up, the attending cardiologist was making rounds and asked the patient his occupation.

"I'm a malpractice attorney."

Smiling, the cardiologist immediately asked, "How was my consent?"

"Perfect.  Absolutely perfect."

-Wes

On the Joy of Medicine

Medicine is unique because it involves people.  While people make this job challenging, they also make this job the best job in the world.  Today was no exception.

Today I met a new patient who has allowed me to share a brief story and a snippet of his medical history here on this blog.  His name is Mr. Carl Bogaard.

On January 9, 2012, Mr. Bogaard wrote a brief note to the Chicago Tribune that said simply:

"My family is treating me like a hero just because I am going to be 95 years old. How lucky can I be to have a family like that?"

The letter was noticed by a local radio personality, Jonathan Brandmeier from WGN, who contacted Mr. Bogaard and learned that he performed 50 push-ups a day, every day.  So he decided to invite him to a push-up competition.  Take a moment to view Mr. Bogaard's YouTube video of his competition:



While this video is remarkable in its own right, there is a little something else you should know.

Mr. Bogaard has a permanent pacemaker that was implanted in 2009 for complete heart block and is completely dependent on his pacemaker for his heart to beat.  Oh, and he really did 59 push-ups.

Now you know why I love my job.

-Wes

Ectopia Cordis

If a baby is born with a portion of her heart outside the chest, what do you do?

Why, make a new chest, of course (video).

-Wes

You Know You Need a Pacemaker When...

... your pause, when held vertical, exceeds one third of your height:

Strip recorded 1.5 years after implant of an implantable loop recorder showing new 27-second pause (Period between large black boxes on the strip represent six seconds each - click to enlarge).

-Wes

High Voltage Riata ST Defibrillator Lead Failure and Its Implications for Durata

It came from a case report published online before print in PACE from Dr. John Marenco of Tufts University in Springfield, Massachusetts:

A 60-year-old man had a single-chamber St.Jude Atlas VR defibrillator (St. Jude Medical, St. Paul, MN, USA) with a dual coil St. Jude Riata 7001 defibrillator lead (My note: this is actually a downsized, second-generation 7 Fr Riata ST model whose internal construct shares many similarities to St. Jude's currently-marketed third-generation 7 Fr Durata lead) placed in 2006 for primary prevention secondary to an ischemic cardiomyopathy and prior myocardial infarction.  All routine device interrogations, both remote and in-office, had been normal with stable sensing amplitude, lead impedances, and capture thresholds. The device was programmed with two zones: a ventricular tachycardia (VT) zone from 340 ms (176 beats/min) and a ventricular fibrillation (VF) zone from 260 ms (231 beats/min).  The VT zone had a morphology discriminator “on” with interval stability and sudden onset “passive.” Five years from implant, he presents with palpitations, light-headedness, and a single implantable cardioverter defibrillator (ICD) discharge.  He has a friend drive him to the emergency room and is found to be in ventricular tachycardia over 200 beats/min. The ventricular tachycardia terminated with intravenous amiodarone bolus before need for external defibrillation. Device interrogation demonstrated an initial rhythm of atrial fibrillation with the appropriate detection of the onset of ventricular tachycardia with a cycle length of 245 ms, within the device’s VF zone (Fig. 1). Discriminators were not activated in the VF zone, but the morphology discriminator clearly demonstrates a failure of the electrogram signal to match the template (indicated by the “x” in the marker channel). After detection of 12 intervals (interval average) within the VF zone an episode is declared and a 25-Joule (693 V) shock is delivered, failing to restore sinus rhythm.  No additional shocks are delivered despite appropriate redetection within the VF zone (Fig. 2).  After a fifth detection, the device declares “no more therapies” with VT continuing indefinitely. Device interrogation in the emergency department reveals a pacing lead impedance was 465 ohms, signal amplitude 1.8 mV, and capture threshold 0.75 V at the rate of 0.5 ms. What is the differential diagnosis of failure to deliver appropriate therapy and why did this device fail to deliver more than a single shock?

Further review of the case's figure disclosed appropriate VT detection, a high voltage impedance of 0 ohms, and an "aborted charge because of possible output circuit damage" on device interrogation after the event.  Importantly, at the time of lead revision, "there was no fluoroscopic insulation breach and no obvious insulation breach in the pocket."  Fluoroscopic screening of these leads, therefore, would not have detected pending lead failure.  Further, as far as we can tell from the report, no antecedent device alerts were triggered before this event.

This case report discloses several important issues. (1) High voltage coil damage in a 7Fr  Riata ST lead can lead to either ineffective high voltage therapy delivery, withholding of further therapies, or both despite appropriate arrhythmia detection.  St. Jude defibrillators are engineered to automatically withhold energy delivery in low high-voltage lead impedance situations to avoid excessive current delivery and device overheating in such circumstances (personal communication).  (2) This failure mechanism, while curently very rare, may affect implanters decisions regarding whether or not to replace existing Riata leads irrespective of their performance characteristics and flouroscopic appearance at the time of battery change.  Already there have been other reported high voltage failures in Riata leads with externalized wires.  Some have advocated testing the high voltage leads as part of Riata lead follow-up to screen for this failure mechanism, especially since the therapeutic implications of high voltage lead failure is much more significant and difficult to detect than low-voltage (sensing lead) failures. 

Perhaps most important for St. Jude going forward is how this case will influence implanters' choice of later-generation 7 Fr St. Jude defibrillator leads with their Optim coating but similarly-downsized inner lumen dimensions.  I look forward to St. Jude's update of their Riata Communications website regarding these recently published case reports.

-Wes

References:

Marenco JP. "Failure to Deliver ICD Shocks after a Failed Discharge Despite Redetection of Rapid Ventricular Tachycardia? What Is the Cause?" PACE DOI: 10.1111/j.1540-8159.2012.03484.x Published online 21 July 2012.

For an excellent overview of the Riata ICD lead recall by Dr. Jay Schloss: http://cardiobrief.org/2012/02/22/guest-post-more-lessons-from-the-riata-icd-lead-recall/

Just a Rash

He was referred for consideration of a biventricular ICD implant after a failed attempt at an outside institution. When listening to his lungs posteriorly, a 'little' rash was noted:

Click image to enlarge

What is this?

-Wes

EKG Du Jour #25 - The Exercise Enthusiast

He was a 65 year-old previously healthy avid exercise enthusiast on no medications who was referred for evaluation of two near-syncopal episodes. The first episode occurred approximately 10 minutes after he stopped exercising on a treadmill. He felt he had to grab the wall to prevent himself from falling.

The second occurred after riding his bike home from the gym. Just after riding his bike home, he became very lightheaded and felt he had to sit on his front porch and nearly lost consciousness. His symptoms passed after resting for about 20 minutes.

While having his blood pressure checked, the nurse noted an irregular pulse. He felt fine and was unaware of his heart rhythm. A 12-lead rhythm strip was obtained and two representative 12-lead rhythm strips from the recording are shown below:

Click image to enlarge

Click image to enlarge

Any ideas? What therapy (therapies?) would you recommend?

-Wes

Strips used with patient permission.

HIPAA, Case Reports, and the "Small Cell" Problem

It was an interesting tweet that referenced a soon-to-be-published case report from the Annals of Emergency Medicine (via @EmergencyDocs) that piqued my interest:

Thrilling case study: emergency doc cracked chest to save 42 y/o woman in cardiac tamponade after ablation therapy. http://bit.ly/umnydc

Details about the case are quite specific and the case reports heralds from a town in Minnesota. It describes, in very specific detail, the management of a patient who presented to the emergency room in shock from cardiac tamponade after a catheter ablation procedure for right ventricular outflow tract tachycardia.

Is this unique case report HIPAA compliant?

I would say, according to our current definition of HIPAA's "personal health information," such a case report is not HIPAA compliant. Nor could such a case be mentioned on a blog, for that matter, even though it presents important information for people dealing with these patients.

There is an important quality-of-care role in telling these clinical stories. In fact, HIPAA states there are just "18 little rules" that doctors are supposed to follow when they report important clinical cases. But details about cases may need to be very specific. Specific case reports can bring important specific clinical details to the attention of the medical community. For instance, if doctors had not been willing to describe several cases of pulmonary vein stenosis or two cases of esophageal perforation in a major medical journal years ago, how many more people might have been injured as a result?

But there's problem giving such details about clinical details about patient cases: "the small cell problem:"

Clinicians should be sensitive to the "small cell problem": the existence of individuals with such unique or unusual diagnoses or illnesses, that it might be possible for others (or patients and families themselves) to identify the individuals in case reports or medical text books based upon limited information, such as state or city of residence, age and diagnosis.

The "small cell" problem violates HIPAA and HIPAA means business: millions of dollars of business that gets released in press releases from the Department of Health and Human Services when they catch their prey.

But doctors should not be afraid of publishing case reports especially since there are good reasons for them clinically. Further, when doctors make good faith efforts to conceal patient's personal information in those reports, they should not be subject to threats of HIPAA's "small cell" problem. Simply put: the "small cell" problem is HIPAA's, not the doctors'. Extending the definition of personal health information as defined by HIPAA to include "any other unique identifying characteristic" about a patient's case limits doctors' ability to improve care to our patients while greatly increasing our legal culpability for that effort.

-Wes

From the Archives: Twice Shocked

I still think this case was cool, so I'll link to it once again.

Have a nice weekend.

-Wes