Inferior Transmural Myocardial Infarction Research Articles

Anomalous right coronary artery causing inferior myocardial infarction, diagnosed on the occasion of a life-insurance medical exam

We present a case of an anomalous right coronary artery (RCA) originating from the opposite aortic sinus causing a transmural inferior myocardial infarction in a former competitive cyclist, followed by a brief discussion of the epidemiology, presentation, diagnosis and treatment of this coronary anomaly.

Tissue Cardiovascular Magnetic Resonance Demonstrates Regional Diastolic Dysfunction in Remote Tissue Early After Inferior Myocardial Infarction

To investigate regional diastolic and systolic function using tissue cardiovascular magnetic resonance (CMR), early after transmural myocardial infarction of the inferior wall due to single proximal right coronary artery disease. Velocity encoded CMR was used to measure early diastolic transmitral flow velocity (E), and regional, longitudinal, myocardial systolic (Sa) and early diastolic (Ea) velocities (tissue CMR) in 15 patients with a recent transmural inferior myocardial infarction and in 15 age and LV-mass index matched control subjects. An unpaired two-tailed t test was used to assess significance of continuous variables. Global systolic (ejection fraction 46 +/- 7% versus 57 +/- 4%, p = 0.000052) and global diastolic LV function (average Ea of infarcted or inferior, remote or anterior, adjacent or septal and lateral myocardium 6.8 +/- 1.7 cm/s versus 10.4 +/- 1.5 cm/s, p = 0.0000012) were impaired in patients as compared to controls. Regional systolic and diastolic LV velocities were impaired in infarcted and adjacent tissue in patients. However, in remote or anterior tissue, systolic velocities were preserved (Sa 6.6 +/- 2.0 cm/s versus 6.8 +/- 1.4 cm/s, p = 0.70), but diastolic velocities were impaired in patients as compared to controls (Ea 7.2 +/- 2.3 cm/s versus 10.2 +/- 2.5 cm/s, p = 0.0026). Regional diastolic velocities early after inferior myocardial infarction are impaired in the infarcted, adjacent and remote tissue, but regional systolic velocities are preserved in remote tissue.

Viability and differentiation of autologous skeletal myoblast grafts in ischaemic cardiomyopathy

Autologous skeletal myoblast transplantation might improve postinfarction ventricular function, but graft viability and differentiation (ie, proof of concept) has not been shown. A 72-year-old man had autologous cultured myoblasts from his vastus lateralis injected to an area of transmural inferior myocardial infarction in non-reperfused scar tissue. He showed improvement in symptoms and left-ventricular ejection fraction. When he died 17.5 months after the procedure, the grafted post-infarction scar showed well developed skeletal myotubes with a preserved contractile apparatus. 65% of myotubes expressed the slow myosin isoform and 33% coexpressed the slow and fast isoforms (vs 44% and 0.6%, respectively, in skeletal muscle). Myoblast grafts can survive and show a switch to slow-twitch fibres, which might allow sustained improvement in cardiac function.

Standard 12-lead ECG versus special chest leads in the diagnosis of right ventricular myocardial infarction

The case of a 60-year-old woman with an acute inferior transmural myocardial infarction associated with a right ventricular myocardial infarction provided an opportunity to compare the performance of the 12-lead electrocardiogram (ECG) and the right chest leads in the diagnosis of infarction of the right ventricle. While the right chest leads revealed unequivocal evidence of ischemic injury emanating from the right ventricle, the standard leads II and III showed changes compatible with inferior myocardial infarction; familiarity with vectorial interpretive concepts of ST segment deviations could provide a hint of an associated right ventricular involvement. This report is presented at a time of renewed controversy regarding the necessity of special ECG leads in the diagnosis of acute right ventricular infarction in the routine emergency department environment.

Long-term results of surgical treatment for mitral regurgitation with severe left ventricular dysfunction after myocardial infarction caused by Kawasaki disease

Cardiovascular involvement is the major cause of morbidity and mortality among children with Kawasaki disease. 1 Mitral regurgitation (MR) is one of the major determinants of long-term survival after myocardial infarction caused by Kawasaki disease. 2 Only a few reports discuss surgical treatment for this cardiac abnormality, however, and its long-term results have been unknown, 3-4 especially in patients with severe left ventricular (LV) dysfunction. In this report, we describe two cases of Kawasaki disease with refractory congestive heart failure caused by massive MR after myocardial infarction, as well as long-team results of surgical treatment (Table I).

Analytic Review: Right Ventricular Infarction

Right ventricular myocardial infarction (RVMI) usually occurs after occlusion of a dominant right coronary artery, and the amount of right ventricular necrosis depends on whether this occlusion occurs proximal or distal along the length of the coronary artery. In patients who have a considerable amount of right ventricular necrosis, the physical examination reveals an elevated jugular venous pressure and Kussmaul's sign. Acute hemodynamic monitoring demonstrates a disproportionate elevation of the right atrial pressure (RAP) when compared with the pulmonary artery wedge pressure (PAWP). Previously validated hemodynamic criteria for identifying hemodynamically important RVMI include an RAP greater than or equal to 10 mm Hg and a RAP: PAWP ratio greater than or equal to 0.8. These hemodynamic findings can be seen in approximately 10% of patients who are seen with acute inferior transmural myocardial infarction; the findings can be produced in another 10% of patients after volume loading. Radionuclide angiography accurately assesses right ventricular systolic function using either the first pass or equilibrium technique. When the right ventricular ejection fraction is less than 40% and there is evidence of right ventricular wall motion abnormalities, the presence of hemodynamically important RVMI is highly likely. When a patient presents with hypotension and low cardiac index, volume therapy should be instituted initially. However, if cardiac index does not improve after RAP and PAWP have increased to greater than 20% above control values, intravenous dobutamine should be instituted without delay to restore circulatory stability. The acute and long-term prognosis of patients with RVMI is excellent as long as extensive left ventricular necrosis does not occur concomitantly. Furthermore, right ventricular systolic function has been shown to improve significantly in the recovery period so that the patient's functional capacity is not imparied.

Clinical and prognostic importance of persistent precordial (V1-V4) electrocardiographic ST segment depression in patients with inferior transmural myocardial infarction.

Forty-three consecutive patients with acute inferior transmural myocardial infarction but no history or electrocardiographic evidence of prior myocardial infarction were evaluated prospectively to assess the clinical and prognostic importance of persistent precordial (V1-V4) ST segment depression. Patients were evaluated within 24 hr of admission by history, physical examination, cardiac enzyme levels, right heart catheterization, and radionuclide angiography; all were followed for 1 year. Ten of the 43 patients (group I) had persistent anterior precordial ST segment depression, defined as 1 mm or greater in one or more precordial leads (V1-V4) 24 hr after admission to the coronary care unit, and 33 patients (group II) did not. Clinical variables that differed between groups I and II, respectively, included mean age (67 +/- 9 [+/- 1 SD] vs 59 +/- 8 years; p less than .01), incidence of Killip class II to IV (100% vs 33%; p less than .001), and average peak creatine kinase concentration (2878 +/- 1139 vs 1511 +/- 1034 IU/liter; p less than .001). Hemodynamic differences between groups I and II included a higher pulmonary arterial wedge pressure (19 +/- 4 vs 11 +/- 5 mm Hg; p less than .001) and a lower cardiac index (2.0 +/- 0.5 vs 2.6 +/- 0.7 liters/min/m2; p less than .05). An evaluation of left ventricular ejection fraction and wall motion index by radionuclide angiography showed that group I had a lower ejection fraction (44 +/- 11% vs 53 +/- 10%; p less than .05) and higher wall motion index (1.7 +/- 0.4 vs 1.4 +/- 0.3; p less than .05) compared with group II.(ABSTRACT TRUNCATED AT 250 WORDS)

Inferoseptal myocardial infarction: Another cause of precordial ST-segment depression in transmural inferior wall myocardial infarction?

Electrocardiographic ST-segment depression in the anterior precordial leads is a frequent observation during the initial hospital phase of acute transmural inferior myocardial infarction (MI), but is of uncertain significance. No available clinical studies have examined the prevalence of inferoseptal necrosis complicating inferior MI. Therefore, the clinical course, electrocardiographic features, radionuclide angiograms and cardiac enzyme changes in 57 patients with transmural inferior MI who did not have prior anterior or concomitant "true posterior" MI, associated anterior or posterolateral asynergy by radionuclide ventriculography, or left or right bundle branch block were reviewed retrospectively. Patients were categorized according to the presence (group A) or absence (group B) of precordial ST-segment depression and according to the presence (group I) or absence (group II) of radionuclide septal wall motion abnormalities. There were no significant differences in global left ventricular ejection fraction (group A, 49 +/- 8, group B, 52 +/- 41; group I, 51 +/- 7, group II, 51 +/- 6), right ventricular ejection fraction (group A, 45 +/- 9, group B, 42 +/- 7; group I, 43 +/- 8, group II, 41 +/- 8), or clinical outcome in the hospital. However, chi-square analysis revealed a significant (p less than 0.05) association between the presence or absence of septal asynergy and the presence or absence of precordial ST depression. In addition, average peak creatine kinase elevation (group I, 761 +/- 164 IU; group II, 698 +/- 178 IU) attained marginal significance by paired t test (p = 0.06). Precordial ST-segment depression during transmural inferior MI is frequently associated with septal asynergy by gated radionuclide angiography (15 of 26 patients, 58%).(ABSTRACT TRUNCATED AT 250 WORDS)

First transit and equilibrium radionuclide angiography in patients with inferior transmural myocardial infarction: Criteria for the diagnosis of associated hemodynamically significant right ventricular infarction

To define radionuclide criteria for identifying hemodynamically significant right ventricular infarction, 33 consecutive men with inferior transmural infarction were evaluated prospectively by right heart catheterization and first transit and equilibrium radionuclide angiography within 36 hours of the onset of symptoms. Hemodynamically significant right ventricular infarction was present in 6 of the 33 patients (Group I); the remaining 27 patients did not demonstrate the hemodynamics characteristic of right ventricular infarction (Group II). A right ventricular ejection fraction of less than 40% separated Group I and Group II patients by equilibrium (p = 0.003) but not by first transit (p = NS) radionuclide angiography. However, a right ventricular ejection fraction of less than 35% separated Group I and II patients by both techniques (p = 0.02 and p = 0.005, respectively). The presence of a right ventricular regional wall motion abnormality on either first transit or equilibrium radionuclide angiograms separated Group I and II patients (p less than 0.001). The combination of both a right ventricular ejection fraction of less than 40% and a regional wall motion abnormality separated Group I and II patients using either equilibrium (p less than 0.001) or first transit (p = 0.02) radionuclide angiography. It is concluded that in patients with acute inferior transmural myocardial infarction, a right ventricular regional wall motion abnormality alone or in combination with a right ventricular ejection fraction of less than 40% by either first transit or equilibrium radionuclide angiography is a useful criterion for establishing the presence of hemodynamically significant right ventricular infarction, while its absence argues against the diagnosis of right ventricular infarction.

Right ventricular infarction: Identification by hemodynamic measurements before and after volume loading and correlation with noninvasive techniques

To evaluate the potential occurrence of right ventricular infarction, 53 patients with acute inferior transmural myocardial infarction were studied within 36 hours of symptoms by right heart catheterization, equilibrium radionuclide angiography and two-dimensional echocardiography. Technetium-99m pyrophosphate myocardial scintigraphy was performed 3 days after the onset of symptoms. The hemodynamic standard for right ventricular infarction was defined as both a right atrial pressure of 10 mm Hg or more and a right atrial/pulmonary artery wedge pressure ratio of 0.8 or more. Eight (15%) of the 53 patients had hemodynamic measurements at rest characteristic of right ventricular infarction, and 6 (11%) additional patients met these criteria after volume loading (p less than 0.05). Nineteen (37%) of the 51 patients who had radionuclide angiography had right ventricular dysfunction manifested by both a reduced right ventricular ejection fraction (less than 40%) and right ventricular regional wall motion abnormalities (akinesia or dyskinesia). An abnormal radionuclide angiogram was observed in 12 of 13 patients with hemodynamic measurements indicating right ventricular infarction. In 12 patients with an abnormal radionuclide angiographic study, right ventricular ejection fraction improved 6 to 12 weeks after infarction (27 +/- 7 to 36 +/- 9%, p less than 0.01). Twenty-two (49%) of the 45 patients with adequate two-dimensional echocardiograms had a right ventricular regional wall motion abnormality. An abnormal two-dimensional echocardiogram was seen in 9 of 11 patients with hemodynamic measurements characteristic of right ventricular infarction. Technetium-99m pyrophosphate scintigraphy was positive for right ventricular infarction in 3 of 12 patients who had hemodynamic measurements indicating right ventricular infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Is anterior ST depression with acute transmural inferior infarction due to posterior infarction?: A vectorcardiographic and scintigraphic study

The hypothesis that anterior ST segment depression represents concomitant posterior infarction was tested in 49 patients admitted with a first transmural inferior myocardial infarction. Anterior ST depression was defined as 0.1 mV or more ST depression in leads V1, V2 or V3 on an electrocardiogram recorded within 18 hours of infarction. Serial vectorcardiograms and technetium pyrophosphate scans were obtained. Eighty percent of the patients (39 of 49) had anterior ST depression. Of these 39 patients, 34% fulfilled vectorcardiographic criteria for posterior infarction, and 60% had pyrophosphate scanning evidence of posterior infarction. Early anterior ST depression was neither highly sensitive (84%) nor specific (20%) for the detection of posterior infarction as defined by pyrophosphate imaging. Of patients with persistent anterior ST depression (greater than 72 hours), 87% had posterior infarction detected by pyrophosphate scan. In patients with inferior myocardial infarction, vectorcardiographic evidence of posterior infarction correlated poorly with pyrophosphate imaging data. Right ventricular infarction was present on pyrophosphate imaging in 40% of patients with pyrophosphate changes of posterior infarction but without vectorcardiographic evidence of posterior infarction. It is concluded that: 1) the majority of patients with acute inferior myocardial infarction have anterior ST segment depression; 2) early anterior ST segment depression in such patients is not a specific marker for posterior infarction; and 3) standard vectorcardiographic criteria for transmural posterior infarction may be inaccurate in patients with concomitant transmural inferior myocardial infarction or right ventricular infarction, or both.

“Reciprocal” anterior ST depression early in the course of transmural inferior myocardial infarction: an ECG finding of uncertain clinical significance

“Reciprocal” anterior ST depression early in the course of transmural inferior myocardial infarction: an ECG finding of uncertain clinical significance

Nontransmural myocardial infarction: A comparison of hospital and late clinical course of patients with that of matched patients with transmural anterior and transmural inferior myocardial infarction

The hospital and long-term course of 67 patients with nontransmural myocardial infarction was compared with that of 66 patients with transmural anterior and 63 patients with transmural inferior infarction matched for age, sex, previous infarction and prior congestive heart failure. During their hospital stay, patients with nontransmural infarction had significantly less congestive heart failure and fewer intraventricular conduction defects than did patients with transmural anterior infarction; fewer atrial tachyarrhythmias and less sinus bradycardia and atrioventricular block than did patients with transmural inferior infarction; and an incidence of hypotension, pericarditis and ventricular irritability similar to that of patients in the other two groups. Patients with nontransmural infarction had a significantly lower coronary care unit mortality rate (9 percent) than that of patients with transmural anterior or transmural inferior infarction (20 and 19 percent, respectively). By 3 months, the mortality rate had risen to 14 percent in patients with nontransmural infarction, but was significantly higher (29 and 27 percent, respectively) in patients with transmural anterior or transmural inferior infarction. Angina was common in all three groups, occurring in more than 50 percent of patients during a mean follow-up period of 28.6 months after hospital discharge. In contrast, the incidence of subsequent myocardial infarction was significantly greater in patients with nontransmural myocardial infarction, occurring in 21 percent at 9 months compared with only 3 percent of patients with transmural anterior (p <0.01) and 2 percent of patients with transmural inferior (p <0.05) infarction. By 54 months, 57 percent of patients with nontransmural infarction had sustained a new infarction contrasted with only 12 percent of patients with transmural anterior (/p <0.001) and 22 percent of patients with transmural inferior (p <0.01) infarction. Late mortality increased in patients with nontransmural myocardial infarction and, although this group had a significantly better survival rate at 3 months, the overall late mortality of the three groups was comparable. The study suggests that nontransmural myocardial infarction is an unstable ischemic event associated with a great risk of later myocardial infarction and high late mortality rate. A more aggressive diagnostic and therapeutic approach may be warranted in patients with nontransmural myocardial infarction.

Right ventricular infarction: Relationships between ST segment elevation in V 4R and hemodynamic, scintigraphic, and echocardiographic findings in patients with acute inferior myocardial infarction

The relationship between ST segment elevation on the right precordial lead V 4R and the hemodynamic, echocardiographic, and myocardial scintigraphic signs suggestive of right ventricular (RV) infarction was studied in 42 patients with acute inferior myocardial infarction. Twenty-two patients had ST segment elevation in V 4R. Among these patients, a significant correlation was demonstrated between V 4R ST segment elevation and the hemodynamic ( p < 0.001), scintigraphic ( p < 0.001), and echographic ( p < 0.02) criteria for acute RV infarction. These results support the validity of this new electrocardiographic sign as a practical means in alding the clinical detection of RV involvement with acute transmural inferior myocardial infarction.

Precordial ST-segment mapping 5. Analysis of maps and standard electrocardiograms in patients with inferior myocardial infarction

Measured and derived electrocardiographic parameters pertaining to ST-segment elevations, R and Q wave amplitudes from standard electrocardiograms, and 49-lead precordial maps from ten patients with acute inferior transmural myocardial infarction were analyzed. Sums of ST-segment elevations correlated well with corresponding values derived from various combinations of standard leads expressing inferior ischemic injury. Derived ECG R and Q wave data from maps did not correlate with corresponding parameters from the standard ECGs. Stability of parameters derived from ST-segment elevations over the course of the study and lack of correlation with data expressing changes in the R and Q waves were noted. An analytical pattern such as the one utilized in this study can be used for assessment of therapeutic interventions in the Coronary Care Unit.

A rare form of Wenckebach atrioventricular block

Summary A patient with an acute inferior transmural myocardial infarction demonstrated a rare form of Wenckebach atrioventricular block, characterized by increasing P-R intervals, constant P-R increments, and constant R-R intervals, leading to a non-conducted beat. Constant P-R increments (the change between successive P-R intervals) have not been previously described in Wenckebach atrioventricular block.