Importance of recognizing pseudo-septal infarction due to electrocardiographic lead misplacement

Myocardial Infarction Simulated From Improper Telemetry (MISFIT): An Autobiographical Case Report

An electrocardiogram, used to not only assess the rate and rhythm of the heart but also to evaluate for injury to the heart, is performed by attaching 12 leads to the patient's body. A myocardial infarction can be mimicked by the misplacement of the leads. A 58-year-old man with long-distance running-associated bradycardia developed postoperative atrial fibrillation with a rapid ventricular response. He converted to normal sinus rhythm after a single oral dose of 30 milligrams of diltiazem; however, the automated reading of the electrocardiogram performed in the hospital showed new changes suggestive of a postero-lateral myocardial infarction, including Q waves in leads I and aVL, as well as early precordial R wave progression with R waves and positive T waves in V2 and V3, and a dominant R wave (R wave to S wave ratio greater than one) in V2. A cardiac work-up was entirely normal: serial troponin levels, thyroid stimulating hormone, echocardiogram, computerized tomography of the chest, and Doppler studies of the extremities. Lead misplacement during the electrocardiogram was suspected during the subsequent evaluation by an astute cardiologist; the findings were diagnostic for a left arm to right arm limb lead reversal. All the changes in myocardial infarction were absent when the electrocardiogram was repeated in the office. Misplacement of leads during an electrocardiogram is not a rare event; therefore, the clinician needs to consider the possibility of improper placement of the leads when evaluating an electrocardiogram. Indeed, emotional distress, additional diagnostic procedures, and potentially harmful procedures may be experienced by the patient from incorrect diagnoses based on electrode misplacement during an electrocardiogram; in addition, there are often increased costs to the patient and the healthcare system. Therefore, in the setting of an incorrect diagnosis attributed to lead misplacement during the performance of an electrocardiogram, the acronym MISFIT (which uses the first letters of the words "myocardial infarction simulated from improper telemetry") has been introduced. In conclusion, it is important to emphasize that a MISFIT is characterized by an electrocardiogram 'mis'diagnosis of a myocardial infarction that does not 'fit' with the clinical scenario.

Fluoroquinolones and the Risk of Aortic Aneurysm or Aortic Dissection: A Systematic Review and Meta-Analysis

OBJECTIVES

We performed a systematic review and meta-analysis to explore the risk of an aortic aneurysm or aortic dissection following fluoroquinolone administration.

METHODS

PubMed, Cochrane library, ClinicalTrials.gov, Embase and Google Scholar were systematically reviewed for controlled studies including adult patients exposed to fluoroquinolones with a primary outcome of aortic aneurysm or aortic dissection.

RESULTS

The meta-analysis was conducted by pooling the effect estimates of four controlled observational studies (one case-control, one case-crossover and two cohort studies). Fluoroquinolone administration more than doubled the risk to develop aortic aneurysm or aortic dissection within 60 days following fluoroquinolone exposure (adjusted Relative Risk [RR] (95% confidence interval [CI]) = 2.14 (1.93 - 2.36); I2 = 15.8%). The quality of the finding was rated as moderate. The risk increase for aortic aneurysm alone was found to be significant (adjusted RR (95% CI) = 2.23 (2.01 - 2.45); I2 = 0%) while the risk increase for aortic dissection alone was not found to be significant (adjusted RR = 1.88 (0.11 - 3.65); I2 = 74%). In subgroup analysis, the risk increase for aortic aneurysm or aortic dissection appeared to be higher in females compared to males (RR = 1.87 (1.24 - 2.51); I2 = 0% versus RR = 1.58 (1.25 - 1.92); I2 = 0%, respectively) and higher in older patients compared to younger patients (RR = 1.72 (1.37 - 2.07); I2 = 0% versus RR = 1.47 (0.91 - 2.04); I2 = 0%, respectively). Subgroup analysis of two studies which measured the duration-response analysis found that as the duration of fluoroquinolone therapy increased from 3 to 14 days to greater than 14 days, there was an increased risk of aortic aneurysm or dissection.

CONCLUSION

The findings of this meta-analysis confirm the positive association between fluoroquinolones and the development of aortic aneurysm or dissection. The data tend to show that this association may be majorly driven by aortic aneurysm. Additionally, some risk factors appear to prevail including prolonged fluoroquinolone treatment and older age.

Clinical location of the fourth and fifth intercostal spaces as a percent of the length of the sternum

OBJECTIVES

To verify accurate placement of the precordial ECG leads by identifying the 4th and 5th intercostal spaces as a function of the length of the sternum. This should decrease the percentage of lead misplacement leading to misdiagnoses.

METHODS

The population consisted of patients and healthy volunteers. The proposed method compared palpation of the 4th and 5th intercostal spaces to a percentile of the sternal length. Location of the 4th and 5th intercostal space using a simple device was evaluated to assist in proper placement of the precordial leads to obtain accurate diagnosis.

RESULTS

The location of the 4th and 5th intercostal space is related to the length of the sternum. It is 77% of the sternal length that measures 15cm for the 4th intercostal space. The position of the V1 and V2 electrodes decreases to 57% when the sternal length is 26cm. Similar data was obtained to locate the 5th intercostal space with proper position of V4-V6 electrodes. Tables are provided to facilitate this process. An instrument was designed to measure the 4th and 5th intercostal space as a function of the sternal length.

CONCLUSIONS

The location of the 4th and 5th intercostal space is identified based on the length of the sternum.

Significance of a negative sinus P wave in lead V2 of the clinical electrocardiogram

BACKGROUND

A negative sinus P wave in lead V₂ (NPV₂ ) of the electrocardiogram (ECG) is rare when leads are positioned correctly. This study was undertaken to clarify the significance of an unusually high incidence of this anomaly found in ECGs at my institution.

METHODS

One thousand four hundred thirty-five ECGs were randomly selected to determine the incidence and gender frequency in tracings showing positive (PPV₂ ), and biphasic (BPV₂ ) P waves in V₂ , as well as NPV₂ . To those cases with NPV₂ , 84 cases with that anomaly from earlier archived ECGs were added to give a larger group for analysis. Medical records were reviewed for clinical details and other archived ECGs.

RESULTS

PPV₂ , BPV₂ , and NPV₂ were found in 1,216 (84.5%), 150 (10.5%), and 69 cases (4.8%), respectively. Cases with NPV₂ were more likely to be female (46 of 69 or 67.7%) than were those with either PPV₂ (500 of 1,216 or 41.1%; p < .001), or BPV₂ (71 of 150 or 47.3%; p < .01). NPV₂ was commonly associated with ECG findings of left atrial abnormality (LAA), septal myocardial infarction, or a ventricular repolarization abnormality, but when multiple ECGs were available in these cases, such abnormalities were usually absent when there was either PPV₂ or BPV₂ .

CONCLUSIONS

With correct precordial lead placement, NPV₂ is rare and BPV₂ is also uncommon, and their presence should alert one to the probability of high placement of V₁ and V₂ , which can produce ECGs that mimic LAA, septal infarction, and ventricular repolarization abnormality.

A Perplexing ECG

An unusual appearing electrocardiogram (ECG) is sent to the medical director's department for interpretation prior to receiving the actual life insurance application. As a result, no background details are available to provide a clinical context. Preliminary perusal of the ECG suggests several diagnostic possibilities.

Unusual QRS Pattern in the Early Precordial Leads

An asymptomatic, middle-aged man is found to have a QR pattern in lead V1 and a qR pattern in lead V2 of his ECG obtained during routine life insurance applicant screening. The risk assessment implication of this ECG finding is reviewed.

Proposed bedside maneuver to facilitate accurate anatomic orientation for correct positioning of ECG precordial leads V1 and V2: a pilot study

BACKGROUND

Misplacement of right precordial electrocardiogram (ECG) electrodes superiorly is a prevalent procedural error that may lead to false findings of T-wave inversion or QS complexes in V2-possibly triggering wasteful utilization of health care resources. Standard technique for proper placement of V1-V2 entails initial palpation for the sternal angle, pointing to the second intercostal space (ICS), followed by lead fixation at the fourth ICS.

STUDY OBJECTIVE

Because adherence to this approach may be limited by lack of a visual landmark for the second ICS, we assessed an alternative technique.

METHODS

The evaluated technique involved placement of the patient's hand up against the base of his/her neck (H→N maneuver) to help demarcate visually a specific point "X" on the chest.

RESULTS

Of 112 patients studied, "X" landed on the first rib in 2.7%, first ICS in 7.1%, second rib in 56.3%, second ICS in 33.0%, and third rib in 0.9%. Thus, in 89.3% (95% confidence interval 83.6-95.0%) of cases (93.3% of men, 84.6% of women; p=0.13), the second ICS could be identified by H→N via the following simple rule: Utilize "X" if it overlies an ICS; or the immediately subjacent ICS if "X" overlies a rib.

CONCLUSION

The H→N maneuver provides a primarily visual approach to identifying the second ICS and, thereby, the fourth ICS for affixing V1-V2. If the present initial experience is confirmed, H→N might merit consideration as an educational tool to promote anatomically correct placement of these precordial leads, a prerequisite to diminishing the incidence of ECG procedure-related "septal ischemia/infarction."