Rezaie’s Evidence-Based Evidence of the Literature

Door to Balloon Time: Are We Measuring the Right Thing?

human_heart_bandaid_pc_1600_clr_1770Door-to Balloon (D2B) time is a time measurement that starts with patient arrival to the emergency department (door) and ends when a catheter crosses a culprit lesion in the cardiac cath lab (balloon). The benefit of prompt primary percutaneous coronary intervention over thrombolytic therapy for acute ST elevation myocardial infarction is very well established. Because of this “time is muscle” strategy, the American College of Cardiology (ACC) launched a national Door to Balloon (D2B) initiative in November 2006. The purpose of this was to recommend a D2B time of no more than 90 minutes. Currently, there is quite a bit of effort put into this guideline by cardiology and emergency medicine, but are we measuring the right thing?

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2016-11-11T19:03:45-07:00

High Sensitivity Troponin Testing

Lab_blooddraw copyTroponin testing is an important component of the diagnostic workup and management of acute coronary syndromes (ACS). The increasing sensitivity of troponin assays has lowered the number of potentially missed ACS diagnoses, but this has also created a diagnostic challenge due to a decrease in the specificity of the test. From 1995 to 2007, the limit of troponin detection fell from 0.5 ng/mL to 0.006 ng/mL (see below graph). Robert Jesse summed up this frustration with the following quote:

When troponin was a lousy assay it was a great test, but now that it’s becoming a great assay, it’s getting to be a lousy test.

 

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2016-11-11T19:03:27-07:00

Bundle Branch Blocks (BBBs) 101

722px-Electrical_conduction_system_of_the_heartRecently, I have been asked by several students at my home institution (UTHSC at San Antonio) to help them understand bundle branch blocks.  This is different than some of my usual posts because it is meant to be more educational than evidence based.  So here we go.  The normal conduction system of the healthy heart is shown to the right.  If there is a delay or block in the left or right bundle, depolarization will take longer to occur. Therefore we get a widened QRS (>0.12 sec or >3 small boxes).

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2016-11-11T19:03:02-07:00

R-Wave Peak Time (RWPT) in Lead II: One Simple Step to Differentiate Wide Complex Tachycardias

RWPT-VT-2There are several algorithms that are currently used to help distinguish Supraventricular Tachycardia (SVT) with aberrancy and Ventricular Tachycardia (VT). Many of these algorithms lack specificity, and let’s face it, who can remember if the absence of an RS complex in the precordial leads is VT or SVT with aberrancy. So what if there was a criterion that had a good sensitivity (SN), specificity (SP), and was one simple step?

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2016-11-11T19:03:00-07:00

Supraventricular Tachycardia (SVT): Are Troponins Necessary?

heart_beat_cardiogram_1600_clr_5646More than one third of patients will have chest pain associated with SVT causing providers to order troponins and other cardiac enzymes. Elevated troponins are not pathognomonic for CAD/ACS and could represent other etiologies such as sepsis, subarachnoid hemorrhage, and pulmonary embolism. Also, subsequent coronary angiography is not necessary for risk stratification in all cases. SVT causes a rapid heart rate, which is well documented as a cause for modest troponin elevation secondary to cardiac stretch, poor diastolic perfusion, and/or coronary artery vasospasm.

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2016-11-11T19:02:44-07:00

Posterior Myocardial Infarction: How Accurate is the Flipped ECG Trick?

Mirror ImagePosterior myocardial infarction (MI) represents 3.3 – 21% of all acute MIs and can be difficult to diagnose by the standard precordial leads. Typically, leads V7 – V9 are needed to diagnose this entity. Luckily, leads V1 – V3, directly face the posterior wall of the left ventricle and are the “mirror image” of the posterior wall of the left ventricle.

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2016-11-11T19:02:45-07:00

Acute Coronary Syndrome (ACS) in the Elderly

Screen Shot 2013-07-18 at 5.09.00 PMAcute coronary syndrome (ACS) is the number one cause of mortality in patients older than 65 years old. 1 To complicate this fact further, they also present atypically with weakness, nausea/vomiting, fatigue, and shortness of breath.  It has been shown that older adults who present to the emergency department (ED) with ACS and a chief complaint other than chest pain have worse outcomes:

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2016-11-11T19:02:34-07:00