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Posterior myocardial infarction: unique diagnosis to an elusive problem
American Journal of Emergency Medicine (2008) 26, 520.e5–520.e6
www.elsevier.com/locate/ajem
Case Report Posterior myocardial infarction: unique diagnosis to an elusive problem Abstract The clinical presentation of posterior myocardial infarction is not easy. The diagnosis is often missed due to lack of ST-segment elevation in standard 12-lead electrocardiogram. The diagnosis is made by seeing ST-segment elevation in the posterior leads V7, V8, and V9, which are typically placed in the left posterior axillary line, left midscapular line, and halfway between the mid scapular and left paraspinal line, respectively [1]. The investigators describe a case of posterior myocardial infarction where additional posterior leads were placed in the left paraspinal line, right paraspinal line, and right midscapular line, displaying more prominent current of injury than seen with traditional posterior lead placement. This may lead to a more robust identification of posterior myocardial infarction that, in turn, may allow for adequate treatment and triage.
Fig. 1 0735-6757/$ – see front matter © 2008 Elsevier Inc. All rights reserved.
A 70-year-old woman presented to the ED by ambulance after being found to be unresponsive in the bathroom by her family. The duration of time when she was unresponsive when found was unknown. She had some seizure-like activity noticed by the family before paramedic arrival. On presentation she was withdrawing only to pain. The patient was intubated en route for respiratory distress. Her medical history included hypertension, cerebral aneurysm, and hyperlipidemia. Physical exam in the ED revealed a patient with normal heart sounds, clear lungs, and bilateral lower extremity edema. Chest radiograph result was normal. Initial electrocardiogram (Fig. 1) revealed ST-segment depression in V1 through V4 and ST-segment elevation in isolated lead V6. Electrocardiogram with posterior leads V7, V8, and V9 in the traditional location was obtained (Fig. 2), showing 1-mm ST-segment elevation in leads V7 and V8, and 1.5-mm ST-segment elevation in lead V9. Another electrocardiogram was obtained (Fig. 3) with placement of leads in the right mid scapular line (V10), right paraspinal line (V11), and left scapular line (V12), showing significant current of injury with 3-mm ST-segment elevation
520.e6
Case Report
Fig. 2
Posterior myocardial infarction refers to the infarction of the posterior wall of the left that is supplied by either the right coronary artery or the left circumflex artery. Therefore, posterior myocardial infarctions are often involved with lateral wall or inferior wall myocardial infarctions. However, isolated posterior wall myocardial infarctions do occur. This is often difficult to diagnose on the 12-lead electrocardiogram as the 12-lead electrocardiogram does not image the posterior wall well [1]. Furthermore, diagnostic criteria for a posterior wall myocardial infarction are not widely known among clinicians, which may result in missed diagnosis and ultimately inadequate triage and treatment [2]. Several electrocardiographic findings in leads V1, V2, and V3 are suggestive of posterior myocardial infarction, including horizontal ST-segment depressions, tall upright T wave, a tall wide R wave, and an R-/S-wave ratio greater than 1 (in lead V2 only) [1]. Additional leads placed on the posterior thorax might be more sensitive in the detection of posterior wall myocardial infarction. In our patient, ST-segment elevations were seen in the posterior leads V7, V8, and V9. Interestingly, the current of injury was much more prominent when leads were placed in the left paraspinal line, right mid scapular line, and right mid axillary line, lead positions that have not been described in the past. This might be particularly important in a patient who does not meet the criteria of at least 1-mm ST-segment elevation in lead V8 or V9 for a posterior myocardial infarction, as establishing the presence of significant current of injury in the posterior thorax may drastically alter the patient management course. Smit C. Vasaiwala MD Ronald Schreiber MD Cardiology Section Department of Medicine Loyola University Chicago Maywood, IL 60153, USA E-mail address: [email protected] doi:10.1016/j.ajem.2007.08.030
Fig. 3
in all 3 leads. The patient underwent cardiac catheterization and was found to have a left-side dominant circulation with 100% occlusion of proximal left circumflex artery. She underwent successful percutaneous coronary intervention of this lesion. She was transferred to the cardiac intensive care unit for further treatment.
References [1] Brady JW, Erling B, Pollack M, et al. Electrocardiographic manifestations: acute posterior wall myocardial infarction. J Emerg Med 2001;20: 391-401. [2] Perloff JK. The recognition of strictly posterior wall myocardial infarction by conventional scale electrocardiography. Circulation 1964; 30:706-18.
www.elsevier.com/locate/ajem
Case Report Posterior myocardial infarction: unique diagnosis to an elusive problem Abstract The clinical presentation of posterior myocardial infarction is not easy. The diagnosis is often missed due to lack of ST-segment elevation in standard 12-lead electrocardiogram. The diagnosis is made by seeing ST-segment elevation in the posterior leads V7, V8, and V9, which are typically placed in the left posterior axillary line, left midscapular line, and halfway between the mid scapular and left paraspinal line, respectively [1]. The investigators describe a case of posterior myocardial infarction where additional posterior leads were placed in the left paraspinal line, right paraspinal line, and right midscapular line, displaying more prominent current of injury than seen with traditional posterior lead placement. This may lead to a more robust identification of posterior myocardial infarction that, in turn, may allow for adequate treatment and triage.
Fig. 1 0735-6757/$ – see front matter © 2008 Elsevier Inc. All rights reserved.
A 70-year-old woman presented to the ED by ambulance after being found to be unresponsive in the bathroom by her family. The duration of time when she was unresponsive when found was unknown. She had some seizure-like activity noticed by the family before paramedic arrival. On presentation she was withdrawing only to pain. The patient was intubated en route for respiratory distress. Her medical history included hypertension, cerebral aneurysm, and hyperlipidemia. Physical exam in the ED revealed a patient with normal heart sounds, clear lungs, and bilateral lower extremity edema. Chest radiograph result was normal. Initial electrocardiogram (Fig. 1) revealed ST-segment depression in V1 through V4 and ST-segment elevation in isolated lead V6. Electrocardiogram with posterior leads V7, V8, and V9 in the traditional location was obtained (Fig. 2), showing 1-mm ST-segment elevation in leads V7 and V8, and 1.5-mm ST-segment elevation in lead V9. Another electrocardiogram was obtained (Fig. 3) with placement of leads in the right mid scapular line (V10), right paraspinal line (V11), and left scapular line (V12), showing significant current of injury with 3-mm ST-segment elevation
520.e6
Case Report
Fig. 2
Posterior myocardial infarction refers to the infarction of the posterior wall of the left that is supplied by either the right coronary artery or the left circumflex artery. Therefore, posterior myocardial infarctions are often involved with lateral wall or inferior wall myocardial infarctions. However, isolated posterior wall myocardial infarctions do occur. This is often difficult to diagnose on the 12-lead electrocardiogram as the 12-lead electrocardiogram does not image the posterior wall well [1]. Furthermore, diagnostic criteria for a posterior wall myocardial infarction are not widely known among clinicians, which may result in missed diagnosis and ultimately inadequate triage and treatment [2]. Several electrocardiographic findings in leads V1, V2, and V3 are suggestive of posterior myocardial infarction, including horizontal ST-segment depressions, tall upright T wave, a tall wide R wave, and an R-/S-wave ratio greater than 1 (in lead V2 only) [1]. Additional leads placed on the posterior thorax might be more sensitive in the detection of posterior wall myocardial infarction. In our patient, ST-segment elevations were seen in the posterior leads V7, V8, and V9. Interestingly, the current of injury was much more prominent when leads were placed in the left paraspinal line, right mid scapular line, and right mid axillary line, lead positions that have not been described in the past. This might be particularly important in a patient who does not meet the criteria of at least 1-mm ST-segment elevation in lead V8 or V9 for a posterior myocardial infarction, as establishing the presence of significant current of injury in the posterior thorax may drastically alter the patient management course. Smit C. Vasaiwala MD Ronald Schreiber MD Cardiology Section Department of Medicine Loyola University Chicago Maywood, IL 60153, USA E-mail address: [email protected] doi:10.1016/j.ajem.2007.08.030
Fig. 3
in all 3 leads. The patient underwent cardiac catheterization and was found to have a left-side dominant circulation with 100% occlusion of proximal left circumflex artery. She underwent successful percutaneous coronary intervention of this lesion. She was transferred to the cardiac intensive care unit for further treatment.
References [1] Brady JW, Erling B, Pollack M, et al. Electrocardiographic manifestations: acute posterior wall myocardial infarction. J Emerg Med 2001;20: 391-401. [2] Perloff JK. The recognition of strictly posterior wall myocardial infarction by conventional scale electrocardiography. Circulation 1964; 30:706-18.