Cardiogenic shock electrocardiogram
|
Cardiogenic Shock Microchapters |
|
Diagnosis |
|---|
|
Treatment |
|
Case Studies |
|
Cardiogenic shock electrocardiogram On the Web |
|
American Roentgen Ray Society Images of Cardiogenic shock electrocardiogram |
|
Risk calculators and risk factors for Cardiogenic shock electrocardiogram |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: João André Alves Silva, M.D. [2] Syed Musadiq Ali M.B.B.S.[3]
Overview
Attending to the catastrophic outcome of cardiogenic shock in a very short time span, its diagnosis must be reached as early as possible in order for proper therapy to be started. This period until diagnosis and treatment initiation is particularly important in the case of cardiogenic shock since the mortality rate of this condition complicating acute-MI is very high, along with the fact that the ability to revert the damage caused, through reperfusion techniques, declines considerably with diagnostic delays. Therefore and due to the unstable state of these patients, the diagnostic evaluations are usually performed as supportive measures are initiated. The diagnostic measures should start with the proper history and physical examination, including blood pressure measurement, followed by an EKG, echocardiography, chest x-ray and collection of blood samples for evaluation. The physician should keep in mind the common features of shock, irrespective of the type of shock, in order to avoid delays in the diagnosis. Although not all shock patients present in the same way, these features include: abnormal mental status, cool extremities, clammy skin, manifestations of hypoperfusion, such as hypotension and oliguria, as well as evidence of metabolic acidosis on the blood results. An electrocardiogram may be useful in distinguishing cardiogenic shock from other types of shock, such as septic shock or neurogenic shock. A diagnosis of cardiogenic shock complicating acute-MI is suggested by the presence of ST segment changes, new left bundle branch block or signs of cardiomyopathy. However, these findings will depend on the region of the heart affected, as well as on the extension of the lesion.
Electrocardiogram
- Knowing that the most common cause of cardiogenic shock is left ventricular failure following myocardial infarction, the EKG gains increased relevance, as it allows the physician to rapidly confirm the etiology and start proper treatment or order further diagnostic tests. The EKG is good tool to reveal the patient's initial MI, however, in 15-30% of patients it may be nonspecific.[1][2] Common changes include:[3]
- Q waves
- >2 mm ST elevations in multiple leads
- Left bundle branch block
- >3 mm ST depressions in multiple leads, particularly in global ischemia following severe left main coronary artery obstruction
Not all patients in cardiogenic shock present to the hospital with this condition. Some are brought primarily because of a myocardial infarction and then, later during hospital stay, develop cardiogenic shock. To this last group, the repeated EKG alongside with an echocardiogram is also useful for diagnosing reinfarction, possibly following stent thrombosis, in a patient who has had a coronary stent placed recently. It should be noted that the absence of EKG changes is also relevant, as it points out to the importance of other causes for cardiogenic shock.[1]
- In the case of cardiogenic shock complicating right ventricular myocardial infarction the EKG is also an important tool, typically showing an MI of the inferior territory. The findings may include:
- >1 mm ST-segment elevations in lead V4R, with a positive predictive value of 87%, representing a good independent predictor of complications, as well as in-hospital mortality[4][5][6]
- New right bundle branch block[6][5][6]
- Atrial fibrillation[7]
- Sinus bradycardia[8]
- Complete heart block
- In acute mitral regurgitation leading to the development of cardiogenic shock, the EKG will have a lesser contribution to the diagnosis, when compared to the previous situations. Nevertheless, relevant findings may include:[1]
- recent posterior and/or inferior MI
- tachycardia
- In the presence of free wall rupture in the setting of an MI, leading to the development of cardiogenic shock, the EKG will most likely reveal low voltages. The findings may include:[1][9]
References
- ↑ 1.0 1.1 1.2 1.3 Ng, R.; Yeghiazarians, Y. (2011). "Post Myocardial Infarction Cardiogenic Shock: A Review of Current Therapies". Journal of Intensive Care Medicine. 28 (3): 151–165. doi:10.1177/0885066611411407. ISSN 0885-0666.
- ↑ Braunwald, Eugene (2012). Braunwald's heart disease : a textbook of cardiovascular medicine. Philadelphia: Saunders. ISBN 1437703984.
- ↑ Longo, Dan L. (Dan Louis) (2012). Harrison's principles of internal medici. New York: McGraw-Hill. ISBN 978-0-07-174889-6.
- ↑ Anderson NE, Ali MR, Simpson IJ (1981). "The clinical significance of right ventricular infarction". N Z Med J. 94 (691): 174–6. PMID 6945508.
- ↑ 5.0 5.1 Zehender M, Kasper W, Kauder E, Schönthaler M, Geibel A, Olschewski M; et al. (1993). "Right ventricular infarction as an independent predictor of prognosis after acute inferior myocardial infarction". N Engl J Med. 328 (14): 981–8. doi:10.1056/NEJM199304083281401. PMID 8450875.
- ↑ 6.0 6.1 6.2 Robalino BD, Whitlow PL, Underwood DA, Salcedo EE (1989). "Electrocardiographic manifestations of right ventricular infarction". Am Heart J. 118 (1): 138–44. PMID 2662727.
- ↑ Sugiura T, Iwasaka T, Takahashi N, Nakamura S, Taniguchi H, Nagahama Y; et al. (1991). "Atrial fibrillation in inferior wall Q-wave acute myocardial infarction". Am J Cardiol. 67 (13): 1135–6. PMID 2024605.
- ↑ Klein HO, Tordjman T, Ninio R, Sareli P, Oren V, Lang R; et al. (1983). "The early recognition of right ventricular infarction: diagnostic accuracy of the electrocardiographic V4R lead". Circulation. 67 (3): 558–65. PMID 6821897.
- ↑ Yang XS, Sun JP, Huang DX (1985). "Cardiac free wall rupture after acute myocardial infarction. Clinical and pathological analysis". Jpn Heart J. 26 (6): 935–41. PMID 3831411.