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Türk Kardiyol Dern Arş - Arch Turk Soc Cardiol 2013; 41:336-339   PMID: 23760122

  Volume: 41  Issue: 4 June 2013   
TKD|Isolated right ventricular myocardial infarction misdiagnosed as anteroseptal myocardial infarction on ECG: a case report

Isolated right ventricular myocardial infarction misdiagnosed as anteroseptal myocardial infarction on ECG: a case report

EKG’de anteroseptal miyokart enfarktüsünü düşündüren tek başına sağ ventrikül miyokart enfarktüsü

Dr. Çağlar Özmen, Dr. Ali Deniz, Dr. Mehmet Kanadaşı

Summary– In this article, we present a case with isolated right ventricular myocardial infarction (MI) who underwent coronary angiography on suspicion of acute anteroseptal MI detected on ECG; however, occlusion of the proximal right coronary artery (RCA) was detected. A female patient aged 65 years was brought to the emergency room due to loss of consciousness 1 hour before. From the patient’s history, it was understood that she had undergone stent placement to her proximal RCA 5 days before. On ECG, a decreasing elevation in ST segment elevation from V1 to V4 was seen, and pathologic Q waves were present at DIII and AVF. A complete AV block was detected on ECG. In the coronary angiography, thrombosis of the stent in the proximal RCA was seen. Stenosis detected in the mid-left anterior descending artery was 50% and at the distal part was 60%. The circumflex coronary artery was found normal. Percutaneous transluminal coronary angioplasty was performed to the 95% thrombotic lesion in the stent of the proximal RCA, and full patency was established. In our case, a decreasing elevation in the ST segment elevation from V1 to V4 was seen. Right ventricular MI usually occurs by an acute stenosis of the non-dominant proximal RCA branch that does not receive collateral flow. In our case, RCA was codominant and an acute stenosis of the stent in the proximal RCA was present. The occlusion of the non-dominant RCA can appear as isolated right ventricular MI without causing a left ventricular infarct, since it does not feed the left ventricle.

Abbreviations:

AV       Atrioventricular
EKG     Electrocardiography
MI       Myocardial infarction

RCA     Right coronary artery

  In acute myocardial infarction (MI) electrocardiography (EKG) provides important information about location of myocardial infarct, and identification of the occluded coronary artery. Right ventricular MI associated with inferior  MI, is a well known, and frequently encountered condition.[1] Since isolated right ventricular MI is seen quiet rarely, its EKG signs are usually overlooked.  Isolated right ventricular MI occurs as a result of occlusion of a non-dominant right coronary artery (RCA) branch which supplies the right ventricle.

  In this case report, we present a case with an isolated right ventricular MI who underwent coronary angiographic examinations with the suspect stent thrombosis, which in fact revealed a stent thrombosis involving proximal  segment of RCA.

CASE PRESENTATION

   A 65-year-old female patient was brought to the emergency room because of loss of consciousness developed one hour previously. From her medical history, it was learnt that a stent had been implanted into proximal RCA  5 days ago. On her physical exam , blood pressure and pulse rate were found to be 100/75 mmHg , and  38bpm, respectively. Her auscultated pulmonary sounds were unremarkable.  Peripheral pulses were not abnormal. Jugular vein distension was noted. Pretibial edema, hepato-, and splenomegaly were not detected. On ECG, a ST segment elevation with a decreasing amplitude from V1 to V4, and pathologic Q waves in DIII and AVF were detected.  Heart rhythm tracings were consistent with complete AV block  (Figure  1).

   The patient was urgently brought into the catheterization laboratory, and a transient pacemaker was implanted. Coronary angiography demonstrated occlusion of proximal RCA with a stent thrombosis (Video 1*). Stenotic  mid- (50 %) , and distal (60%) segments of the left anterior descending artery were detected. Circumflex coronary artery was of normal caliber (Video 2*). Percutaneous coronary balloon angioplasty was applied on the in-stent thrombotic lesion which caused  a 95 % stenosis in the  proximal RCA, and full patency was ensured (Video 3*).

  Soon after balloon angioplasty procedure targeted at relieving her stent thrombosis, complete AV block resolved completely. On electrocardiograms  obtained one day later, disappearance of  ST- segment  elevation, but persistence of abnormal Q waves in DIII, and aVT were seen (Figure 2).

       Transthoracic echocardiograms of the patient revealed a 50 % ejection fraction, and preservation of the left ventricular function with decreased contractility of the right ventricle.


DISCUSSION

  Apart from MI, premature depolarization, Prinzmetal angina, left ventricular bundle branch block, left ventricular hypertrophy, pericarditis, left ventricular aneurysm, Brugada syndrome, and Takotsubo syndrome can be enumerated as conditions which induce ST-segment elevation in anterior leads.

 In Brugada syndrome, on EKG, right bundle branch block concomitantly with ST-segment elevation in V1-V3 leads are observed. In our case, ST-segment elevation was detected in V1-V3, without any morphological evidence of right bundle branch block.


   In Takotsubo cardiomyopathy, echocardiograms demonstrate left ventricular systolic dysfunction, and generally apical ballooning is seen. Coronary angiograms are unremarkable without any coronary artery disease. In our case presence of stent thrombosis in RCA, and normal ventricular systolic functions discarded the possibility of Takotsubo cardiomyopathy

     Premature repolarization is defined as the presence of J point, and ST-elevation at least 1 mm (0.1 mV) above the isoelectric baseline  on EKG. In this group of patients ST-segment elevation can not be explained by the presence of another etiological factor.

     In Prinzmetal angina, chest pain, and transient ST-segment elevation occur. On coronary artery angiograms, coronary artery spasms are observed.  In pericarditis, widespread ST-segment elevation in all derivations, and chest pain specific to pericarditis are noted.

      In nearly 40-50% of the patients with inferior MI, partial involvement of the right ventricle is seen.[2] However in necroptic studies, isolated right ventricular myocardial infarction have been demonstrated only in 1.7-2.4 % of  patients with MI.  Isolated right ventricular MI is recognized by ST-segment elevation with a decreasing amplitude from V1 to V4 without any subsequent occurrence of  Q wave. Its EKG imitates anterior wall MI.[3] In our case, ST-elevation on EKG gradually decreased in amplitude from V1 to V4.  Right ventricular MI generally develops as a result of sudden occlusion of non-dominant proximal segment of RCA which does not receive collateral blood flow.[4] In our case non-dominant RCA was occluded with a stent thrombosis in its proximal segment

      Right ventricular MI is characterized by hypotension, neck vein distension, and  subtle pulmonary symptoms. If it is not associated with  ST-segment elevation in inferior leads, it can be easily overlooked.

     Non-dominant RCA supplies  free wall of the right ventricle, and also AV node. Complete AV block was seen in our case, and decreased contractility of the right ventricle was noted on echocardiograms. Since complete occlusion of non-dominant RCA does not impair perfusion of the left ventricle, complete occlusion of the non-dominant RCA can manifest itself with isolated right ventricular infarct without triggering left ventricular infarct.

    In conclusion, in cases with suspect anteroseptal MI whose EKGs demonstrate ST-segment elevation with a decreasing amplitude from V1 to V4, the culprit lesion must  be thought to be possibly  located  in the proximal segment of non-dominant RCA.

*Video files are available in the website address of the article

Conflict of interest: None declared

REFERENCES

1. Erhardt LR. Clinical and pathological observations in different types of acute myocardial infarction. A study of 84 patients deceased after treatment in a coronary care unit. Acta Med Scand 1974; Suppl 560:7-78.

2. Ozdemir K, Altunkeser BB, Içli A, Ozdil H, Gök H. New parameters in identification of right ventricular myocardial infarction and proximal right coronary artery lesion. Chest 2003;124:219-26.

3.  Shah PK, Maddahi J, Berman DS, Pichler M, Swan HJ. Scintigraphically detected predominant right ventricular dysfunction in acute myocardial infarction: clinical and hemodynamic correlates and implications for therapy and prognosis. J Am Coll Cardiol 1985;6:1264-72.

4.Chou TC, Van der Bel-Kahn J, Allen J, Brockmeier L, Fowler NO. Electrocardiographic diagnosis of right ventricular infarction. Am J Med 1981;70:1175-80.

Key words: Cardiac  ventricle; coronary angiography; coronary circulation/physiology; myocardial infarction/physiopathology; ventricular function, right/physiology.

 

 










 
   
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