Monday, April 29, 2013

Masquerading bundle branch block: what is it?

Quite often one encounters a wide QRS in the dominant rhythm of the electrocardiogram which may have features of either or both bundle branch blocks but is typical of neither. It is often referred to as nonspecific intraventricular conduction delay (IVCD). If the condition is chronic and stable (that is, not due to external factors such as drug effects or hyperkalemia) it generally represents diffuse myocardial scarring and it's a sure bet the patient's ejection fraction will be reduced.

One such pattern, recently described in this paper which caught my eye, is characterized by the RBBB pattern in the precordial leads but with the LBBB pattern in the limb leads and has been termed masquerading BBB. It has been conceptualized in various ways but represents bilateral conduction system disease as a reflection of multifocal myocardial scarring, reflecting extensive damage. It tends to be a poor prognostic sign.

One of the early papers on this topic, back in the days of physician-scientists when autopsies were done and doctors were actually interested in clinicopathological correlations, is here and it is a fascinating read.

Sunday, April 28, 2013

Overuse of PICCs in CKD patients

PICCs (or PICC lines to those suffering from the redundant acronym syndrome) have become popular because they offer a convenient option for IV access and blood sampling. They are becoming the default option for patients who are a “tough stick” or have special IV therapy needs. These are usually the sicker patients who are likely to have CKD. But there's a problem in CKD patients. PICC use may jeopardize future dialysis access and current guidelines discourage the practice.

But a recent study presented at the National Kidney Foundation meeting (via Medpage Today) showed that the practice is common in advanced CKD patients. According to one of the discussants:

She explained that at her institution, they have started a program to reduce PICC placement in CKD patients. "For anyone with a glomerular filtration rate of less than 30 mg/L, you cannot just order a PICC. You have to go through an algorithm where you consider other line placements."

Saturday, April 27, 2013

Long term central venous catheter related infections: what to do?

Remove? Treat through? Antibiotic lock?

A practical review is presented here and the IDSA guidelines for IV catheter related infections in general are here.

Thursday, April 25, 2013

Cerebral vein thrombosis review

From the paper:

Dural sinus or cerebral venous thrombosis (CVT) is a frequently unrecognized cause of stroke affecting predominantly young women. Typical clinical signs include headache, visual problems and seizures.

Fairly easy to diagnose and treat once you think of it.

Wednesday, April 24, 2013

Alcoholic hepatitis

An update. Free full text via Medscape.

Non-evidence based use of IVC filters

Recent paper here in JAMA Internal Medicine. Variability may be driven by the paucity of high level data, variable resources at different hospitals and marked variations in current guidelines.

Perspective offered here in Medpage Today.

Monday, April 22, 2013

What makes a great diagnostician?

Pause for a little metacognition by reading these tips. None of them will do you any good, of course, if you don't have enough time to spend with patients.

Sunday, April 21, 2013

Idiopathic ventricular tachycardias

Most are outflow tract tachycardias and most of those are right ventricular. They are unique in that while they tend to be benign they may cause tachycardia mediated DCM and are amenable to ablation. (They may respond to calcium blockers too but leave that to the experts). Also don't forget that right ventricular cardiomyopathy may manifest as RV tachycardia. This review focuses on RVOT.

Saturday, April 20, 2013

Aspirin: should we add it to our pneumonia order sets?

It has been known for a while now that pneumonia is a short term risk factor for acute coronary syndrome. So it recently occurred to some investigators to see if adding an aspirin a day to the regimens of pneumonia patients would help. The results were startling:

..the rates of ACS at 1 month were 1.1% (n=1) in the aspirin group and 10.6% (n=10) in the control group (relative risk, 0.103; 95% confidence interval 0.005–0.746; P=0.015). Aspirin therapy was associated with a 9% absolute reduction in the risk for ACS. There was no significant decrease in the risk of death from any cause (P=0.151), but the aspirin group had a decreased risk of cardiovascular death (risk reduction: 0.04, P=0.044).

Friday, April 19, 2013

Budd–Chiari update

New review here (free full text provided by Medscape).

Points of interest:

Budd–Chiari syndrome is a rare disorder caused by hepatic venous outflow obstruction and resulting hepatic dysfunction....
BCS is defined as hepatic venous outflow obstruction at any level from the small hepatic veins (HV) to the junction of the IVC and the right atrium, regardless of the cause of obstruction. Outflow obstruction caused by the sinusoidal obstruction syndrome (formerly 'veno-occlusive disease') and cardiac disorders is excluded...
Hepatic venous outflow obstruction caused by external compression or invasion of the venous lumen is termed secondary BCS and is seen with malignant tumors or large cysts...

B-C can be considered a disease of thrombophilia:

At least one thrombophilic disorder is identifiable in 84% of patients and multiple disorders are found in 46%...
Myeloproliferative disorders (MPD) deserve specific mention due to their high frequency in BCS. MPD result in excess cell production by the bone marrow and include: chronic myeloid leukemia, primary myelofibrosis, polycythema rubra vera and essential thrombocytosis. These disorders are particularly common in patients with BCS and may be overt or occult (occurring with normal peripheral blood counts). MPD is found in 49% of BCS cases who undergo a bone marrow examination.

The importance of JAK 2:

In the setting of BCS or splanchnic thrombosis, the positive predictive value rises further and JAK2 (V617F) mutation is a very reliable marker for MPD. A recent meta-analysis of 23 studies reported a pooled prevalence of 37 and 24% of patients with BCS and portal vein thrombosis respectively.

That said, virtually all the other thrombophilias have been associated with B-C.

The clinical presentation can be acute (with abdominal pain) or chronic, and range from asymptomatic to acute liver failure and include encephalopathy, variceal bleeding and splenomegaly.

In addition to treatment of any underlying diseases and general supportive management of the liver disease anticoagulation, shunting, vascular stenting and transplant are discussed as treatment options. There is very limited experience with thrombolysis.

Thursday, April 18, 2013

Precious bodily fluids honors William Stone

Bill Stone is another member of that dying breed of physician-scientists and master clinicians. He was a nephrology attending at the Nashville VA and Vanderbilt Hospital across the street when I was a medical student there. He had a superficial reputation for being a bit malignant but to those who knew him well he was a dedicated physician and teacher who cared greatly about the students and house staff. He was a walking encyclopedia of internal medicine. I was too intimidated to fully appreciate his teaching gifts.

Joel Topf at Precious Bodily Fluids has recently written a post in his honor which lists his 23 “rules of Stone” and mentions his research. Among many other things he discovered beta-2 microglobulin amyloidosis in hemodialysis patients.

Another of his research accomplishments impressed me as a med student. Back then IV penicillin G was used to treat a lot of serious infections. Every now and then patients with renal impairment would experience penicillin neurotoxicity and seize. Thus was born the notion that doses of pcn that were appropriate for normal renal function were “comparably massive” in patients with renal failure. Stone and one of the ID fellows got together, looked at the pharmacokinetics and worked out a method for “renal dosing” of pcn.

Of his 23 rules I like #18: “If an older doctor writes an axiom or a diagram on a piece of paper, ask if you can have it.” (Now some EBM apologists who decry experience and expertise as a basis for learning won't like this).

Sometimes I feel a little worn down by the legal and administrative baggage I face in practice. Reflecting on the legacy of the exemplars of internal medicine is therapy for me.

The asthma-COPD overlap syndrome

ACOS, reviewed here. From the review:
ACOS accounts for approximately 15–25% of the obstructive airway diseases and patients experience worse outcomes compared with asthma or COPD alone. Patients with ACOS have the combined risk factors of smoking and atopy, are generally younger than patients with COPD and experience acute exacerbations with higher frequency and greater severity than lone COPD.

It is not yet a well defined clinical entity, but is a useful construct.

Tuesday, April 16, 2013

Patent foramen ovale in patients with obstructive sleep apnea

According to this study it is common in patients with OSA and its coexistence is associated with more profound nocturnal desaturation. In the small number of patients in the study, closure did not help.

Monday, April 15, 2013

The fragmented QRS

It indicates myocardial scar no matter what the underlying cardiac disease.

I first blogged it several years ago and the field has since seen further clarification as documented in this review.

Sunday, April 14, 2013

Saturday, April 13, 2013

D-dimer testing and aortic dissection

How useful is it to exclude the diagnosis?

According to one recent review:

The sensitivty of D-dimer test for AD diagnosis is reported as close to 100% in the literature and has a negative predictive value between 92% and 100% [5, 6]. Two meta-analyses confirmed that D-dimer testing is useful for the diagnosis of suspected acute aortic dissection [2, 3].

Additional references here and here.

D-dimer testing combined with the ADD score might be a useful approach.

Thursday, April 11, 2013

More on breath acetone (BA) in heart failure

Via Medpage Today.

Baseline BA values vary widely (many fold) in normal subjects. So, comparison with a patient's baseline may be more useful than the absolute value.

In this study a mass-spectrometry technique was used but simple gas chromatography also works.

This field is very promising. I previously blogged the topic and provided background here.

Wednesday, April 10, 2013

Hypomagnesemia due to PPI use

It's not always benign. A mini-review accompanies this case report. Hypokalemia and hypocalcemia are frequent accompaniments via mechanisms mentioned in the paper.

Friday, April 05, 2013

Transthyretin amyloidosis: an under appreciated entity

From the review:

Transthyretin (TTR) amyloidosis is a systemic disorder characterized by the extracellular deposition of amyloid fibrils composed of TTR, a plasma transport protein for thyroxine and vitamin A that is produced predominantly by the liver. TTR can dissociate from its native tetramer form, then misfold and aggregate into amyloid fibrils that accumulate in various organs and tissues, causing progressive dysfunction. TTR amyloidosis is the most common form of hereditary (familial) amyloidosis, and is caused by mutations that destabilize the TTR protein. TTR amyloidosis also encompasses an age-related amyloidosis known as senile systemic amyloidosis, an acquired disorder mainly affecting men after the age of 60 years, that results from the deposition of wild-type TTR amyloid.

Thursday, April 04, 2013

Statin-diabetes association: what’s the skinny?

From a recent review in CCJM:

The evidence from individual clinical trials is mixed, but meta-analyses indicate that statin therapy is associated with approximately a 9% higher risk of diabetes (an absolute difference of about 0.4%).
We need to interpret this information cautiously. Many potentially confounding factors are involved, and rigorous prospective trials are needed to examine this issue.
The benefit of preventing serious cardiovascular events seems to outweigh the higher risks of diabetes and poorer glycemic control, and we should continue to give statins to patients at moderate to high risk, including those with diabetes, with vigilance for these side effects.

Wednesday, April 03, 2013

New oral anticoagulants for prevention and treatment of VTE

The topic is nicely reviewed here. Of greatest interest is rivaroxaban (Xarelto) as it is the only one among the novel oral anticoagulants approved for treatment of DVT and PE in the US. Although the review summarizes the usual pharmacology and labeling a nagging question concerning rivaroxaban remains: is it time to change practice and if so, how? Now when patients present with DVT or PE do we just give them a pill and call it a day?

That question warrants a close look at the EINSTEIN trials for DVT and PE. In both trials, patients in the rivaroxaban arm were usually pretreated with enoxaparin for a day or two prior to enrollment. So the question of treatment in the first 24 hours or so is not well studied. Second, patients in both trials were excluded if thrombolytic therapy was anticipated, whatever that meant. But it implies that the treatments have not been compared in the sickest of the sick patients. Remember too that the results show non-inferiority rather than superiority to standard treatment. Finally, there are all those pesky post-marketing reports that are sure to follow.

So putting aside for now cost and patient preference considerations what's a hospitalist to do? If you're prone to err on the side of caution you might want to go with the time tested regimens for at least the first 24 hours, particularly in the sicker patients.

I did look this up in UptoDate. At present, acknowledging that this may change, they are recommending traditional treatments (LWMH or UFH followed by VKA) over novel anticoatulants, for the entire treatment course due to more clinical experience with the former.

Tuesday, April 02, 2013

Discussions about NCCAM's chelation study (TACT)

Cardiobrief has posted an update. What amazes me about these discussions is that anyone would take TACT for more than entertainment value. Equally amazing is that JAMA, which is supposed to be a top level journal, would give it the time of day. (Would they loosen their standards in kind for Pharma sponsored trials? Don't think so). The irony is that what some would consider a lower tier journal, the Medscape Journal of Medicine, had the most scientifically rigorous perspective on the trial. (See also here).

At least JAMA did publish one appropriately critical editorial---that of Steven E. Nissen, MD. In it Nissen echoed precisely a concern I expressed several years ago in my Magical Mystery Tour of the TACT study sites when he said:

Execution of a high-quality RCT requires skilled investigators and study coordinators who understand these critical scientific principles. For TACT, more than 60% of patients were randomized at enrolling centers described as complementary and alternative medicine sites. Many of these centers have websites that describe their services, which include an array of unproven therapies ranging from stem cell therapy to regrow breasts after mastectomy, high-dose intravenous vitamin C to treat cancer, and use of cinnamon for treating diabetes to treatment of influenza with antimicrobial essential oils or homeopathic remedies (while warning patients not to undergo immunization). Other sites offer chelation to treat or cure a variety of conditions including autism in children. A common theme of these centers is evident—they appear to attempt to appeal to vulnerable patients who have challenging diseases by offering a variety of unscientific and unproven therapies. Whether a high-quality RCT can be performed at such sites is questionable.

A missing element in most of these discussions is whether, before TACT was even conceived, chelation therapy as a remedy for atherosclerotic disease even deserved further study. It didn't.

Finally, the author or the Cardiobrief piece gave this little shout out to Orac:

The most sustained assault on TACT, and on Krumholz’s position, comes from the highly-regarded skeptic blog Respectful Insolence written by Orac (the pseudonym of David Gorski, a surgical oncologist). In his take-no-prisoners assault on TACT, JAMA, and Krumholz, Orac writes “that JAMA is every bit as guilty as The Lancet was in 1998 when it published Andrew Wakefield’s antivaccine nonsense…. If published at all, TACT should have been published in some crappy, bottom-feeding journal, because that’s all that it deserves.”

Inverted takotsubo cardiomyopathy

In an increasing number of reported cases of stress induced cardiomyopathy, as illustrated in this report, it's the base of the heart rather than the apex that balloons. Although sometimes termed inverted takotsubo cardiomyopathy the left ventriculogram, in contrast to typical cases of apical ballooning, does not resemble a Japanese octopus trap. The entire spectrum might better be termed “stress cardiomyopathy.”

Monday, April 01, 2013

CT pulmonary angiography and the over diagnosis of pulmonary embolism

A recent article in the Texas Heart Institute Journal by Dr. Herb Fred includes this statement:

In the teaching hospital where I work, “fishing” is rampant. By fishing, I mean scanning the body part thought to be the source of the patient's complaint or problem, hoping thereby to reel in some sort of diagnosis.48 In these cases, the physician essentially bypasses the history and physical examination and, guided solely by the patient's chief complaint, proceeds directly to CT scanning with no particular pre-test diagnosis foremost in mind. This sport typically takes place in the emergency department, where almost all patients entering with chest pain (not further described) or shortness of breath (not further defined) promptly undergo contrast-enhanced chest CT. It should be obvious, however, that such robotic, indiscriminate, and unduly expensive screening is bound to uncover pulmonary arterial filling defects every now and then. And it does. The defects occasionally appear in the main or lobar arteries, but most of the time they appear in just 1 or 2 segmental or subsegmental branches—areas where reconstruction artifacts or contrast-streaming can produce a false-positive interpretation. Nevertheless, once these defects are detected, all thinking stops, pulmonary embolism becomes the primary diagnosis, and anticoagulation automatically ensues.

But should it, necessarily? That question, as addressed in this paper, gets a little complicated and it deals with two different situations: 1) pulmonary artery filling defects discovered incidentally when chest CT scanning was done for non cardiovascular indications and 2) filling defects (“positive” study) seen when scanning is done in knee jerk fashion to patients with chest pain without prior careful examination or thought.

It is unclear in many such cases whether anticoagulation is necessary, particularly if the filling defects are subsegmental and isolated.

So one may end up dealing with a situation in which thinking which should have taken place before imaging is considered has to be done after the patient “rules in” for PE. That inevitably leads to more testing, for confirmation and to assess risk coupled with clinical judgment applied better late than never.