Isolated right ventricular infarction presenting as anterior wall myocardial infarction on electrocardiography

Isolated right ventricle infarction is extremely rare, and its electrocardiographic (ECG) signs may be misinterpreted or even missed, especially when a typical clinical picture is lacking. This paper describes a case of isolated right ventricle infarction, recognized only by echocardiography. The patient presented with ST-segment elevation in left precordial leads together with minimal ST-segment elevation in inferior leads on a 12-lead ECG. Angiography revealed the culprit right coronary artery, which was small and nondominant. No significant obstructions were found in the left anterior descending artery. This case demonstrates that the ECG appearance of isolated right ventricle infarction may mimic anterior wall infarction and can be easily missed if not suspected.

Primary angioplasty for isolated right ventricular infarction

We describe a case of isolated right ventricular infarction that has rarely been diagnosed antemortem. Electrocardiogram showed ST segment elevation in left precordial chest, right precordial chest, and inferior leads, which mimicked those of anterior and inferior left ventricular infarction. Coronary angiography revealed that culprit lesion was totally occluded right coronary artery. Infarcted artery was nondominant right coronary artery with branches supplying only right ventricular wall. Restoration of coronary blood flow was obtained by primary stenting and resulted in prompt ST segment normalization in all leads. Despite extensive right ventricular wall motion abnormality, subsequent right ventricular dysfunction was not observed.

Atrial natriuretic factor in patients with right ventricular infarction

To determine the possible role of atrial natriuretic factor in right ventricular infarction, serial measurements of this hormone were performed in 21 patients with acute inferior myocardial infarction. All patients underwent enzymatic, electrocardiographic, echocardiographic and coronary arteriographic studies. Ten patients also had right heart hemodynamic measurements. Eight patients had evidence of an associated right ventricular infarction (Group I) and 13 patients did not (Group II). Enzymatically estimated infarct size, presence of left heart failure and arrhythmias were similar in both groups. Mean arterial pressure in Group I (72.1 +/- 4.4 mm Hg) was significantly lower (p = 0.02) than in Group II (89.5 +/- 4.6 mm Hg). Seven (88%) of the eight patients in Group I had elevated right atrial pressures and a higher incidence than Group II of prolonged hypotension (75%) and right ventricular dysfunction (75%) clinically and by echocardiography. Plasma atrial natriuretic factor levels (mean values +/- SEM in pg/ml) for days 1, 2, 3 and 7 after infarction were, respectively: 152 +/- 30, 165 +/- 48, 199 +/- 27 and 189 +/- 31 for Group I versus 55 +/- 9, 55 +/- 11, 61 +/- 13 and 77 +/- 20 for Group II. The difference between groups was significant for days 1 (p less than 0.05), 3 and 7 (p less than 0.01) and not significant for day 2 (p = 0.07). These findings show that atrial natriuretic factor elevation is part of the neurohumoral response to right ventricular infarction and are consistent with the hypothesis that atrial natriuretic factor may play a pathophysiologic role in the right ventricular infarct syndrome.

Right ventricular myocardial infarction with anterior wall left ventricular infarction: an autopsy study

Right ventricular myocardial infarction has been reported to occur exclusively in association with inferior left ventricular infarction. To determine the frequency of right ventricular myocardial infarction in association with anterior left ventricular myocardial infarction, all hearts with anterior myocardial infarction studied over a 3-year period were examined for evidence of right ventricular necrosis or scar. Of 97 hearts with anterior myocardial infarction, 13 (13%) had anterior right ventricular myocardial infarction. The right ventricular infarcts involved from 10% to 50% (mean 28%) of the circumference of the right ventricular free wall from base to apex. The associated left ventricular infarcts were all anteroseptal and large and involved from 36% to 67% (mean 50%) of the total area of the left ventricular free wall and septum. Nine of the 13 patients underwent equilibrium radionuclide angiography and six had demonstrable right ventricular regional and global dysfunction. Thus, right ventricular myocardial infarction does occur with anterior wall left ventricular infarction, and right ventricular dysfunction may be demonstrable by radionuclide angiography. Further investigation is needed to define the hemodynamic characteristics, clinical importance, and therapeutic implications of anterior right ventricular myocardial infarction.

The efficacy of cibenzoline and propafenone against inducible sustained and nonsustained ventricular tachycardias in conscious dogs with isolated chronic right ventricular infarction: a comparative study with procainamide

The efficacy of intravenous cibenzoline (3 mg/kg), propafenone (4 mg/kg), and procainamide (20 mg/kg) against inducible sustained and nonsustained ventricular tachycardias (VT) was evaluated in 12 conscious dogs with chronic isolated right ventricular (RV) infarction. RV infarct was caused by permanent occlusion of the right coronary artery in the closed-chest dog by intracoronary balloon inflation. Three to 10 days following the occlusion period, programmed electrical stimulation reproducibly induced sustained and/or nonsustained VT, allowing evaluation of antiarrhythmic drug efficacy. Propafenone was effective in preventing the induction of sustained VT in only one out of six dogs tested, but caused a significant (p less than 0.05) slowing of VT rate (269 +/- 13 to 230 +/- 10 bpm). Procainamide had effects similar to those seen with propafenone. Propafenone and procainamide were ineffective against nonsustained VT, and on established sustained VT once induced. Cibenzoline was effective in preventing the induction of sustained VT in two out of seven dogs, an effect which was not significantly different from either propafenone or procainamide. However, cibenzoline was significantly (p less than 0.05) more effective than either procainamide or propafenone in terminating an established induced sustained VT (four out of six dogs). Furthermore, cibenzoline converted nonsustained to sustained VT in four out of seven dogs tested. Histopathologic studies have shown infarction of the basal two thirds of the RV (38.5 +/- 7.8% of the RV) with no left ventricular involvement. It is concluded that the isolated RV infarction model is highly suitable for serial drug testing against inducible VT in conscious dogs, and this model of VT appears to be fairly resistant to standard and newer antiarrhythmic drug therapy.

Inducible sustained ventricular tachycardia and ventricular fibrillation in conscious dogs with isolated right ventricular infarction: relation to infarct structure

The susceptibility of infarcted right ventricular myocardium to inducible ventricular tachyarrhythmias was serially evaluated in 18 conscious dogs during the first 2 weeks after permanent right coronary artery occlusion. Properly timed double premature stimuli applied to the right ventricular outflow tract induced sustained (longer than 1 minute) ventricular tachycardia at rates of 190 to 400 beats/min in nine dogs, and ventricular fibrillation in six dogs. No ventricular arrhythmias could be induced in the remaining three dogs. The zone of premature coupling intervals within which ventricular tachyarrhythmias could be induced decreased in each dog as the infarct aged, and by day 12 after occlusion, no ventricular arrhythmias could be induced in any of the dogs studied. Both the size and the degree of patchiness (graded from 0 for no patchiness to +4 for patchiness throughout the infarct) of the infarct appear to be related to the nature of the induced rhythm. Infarcts with greater heterogeneity and those that were larger than 8% of the right ventricular volume were associated with a higher incidence of ventricular fibrillation, and infarcts with a lesser degree of patchiness were more suitable for sustained ventricular tachycardia (3.4 +/- 1.2 versus 1.4 +/- 0.4, p less than 0.05). These findings indicate that the infarcted right ventricular myocardium, independent of left ventricular involvement, can be associated with malignant ventricular tachyarrhythmias, ventricular tachyarrhythmias can be induced only during a well defined postinfarction period; and both the size and geometry of the right ventricular infarct determine the nature of the induced ventricular rhythm.

Right ventricular myocardial infarction in patients with chronic lung disease: possible role of right ventricular hypertrophy

To determine the relation between right ventricular hypertrophy and right ventricular myocardial infarction in patients with chronic lung disease, the records of 28 patients with chronic lung disease, inferior myocardial infarction and significant coronary artery disease (group I) and 20 patients with right ventricular hypertrophy, chronic lung disease without inferior myocardial infarction or significant coronary artery disease (group II) were reviewed. Chronic lung disease was diagnosed by clinical criteria, chest radiographs and pulmonary function tests. All patients had postmortem examinations. Patients in group I were classified into two subgroups: group Ia (without right ventricular hypertrophy) and group Ib (with right ventricular hypertrophy). Right ventricular wall thickness was 3.3 mm +/- 0.5 in group Ia, 6.0 mm +/- 1.1 in group Ib and 8.8 mm +/- 2.4 in group II (group Ia versus Ib, p less than 0.001; group Ia versus II, p less than 0.001; group Ib versus II, p less than 0.001). Eleven patients (78.6%) in group Ib (chronic lung disease with both right ventricular hypertrophy and inferior myocardial infarction) had right ventricular myocardial infarction compared with only 3 patients (21.9%) in group Ia (chronic lung disease without right ventricular hypertrophy and with inferior myocardial infarction) (p less than 0.008). Isolated right ventricular myocardial infarction occurred in four patients (20%) in group II (chronic lung disease with right ventricular hypertrophy, but without evidence of infarction of the left ventricle or significant coronary artery disease). There was no significant difference in the extent of anatomic coronary disease in groups Ia and Ib.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical significance of incomplete tricuspid valve closure seen on two-dimensional echocardiography

Incomplete closure of the tricuspid valve without apparent cusp disease was noted on two-dimensional echocardiography in 31 patients. This abnormality was defined as a failure of the tricuspid valve leaflet tips to reach the plane of the tricuspid valve anulus by at least 1 cm in the standard apical four chamber view at the point of maximal systolic closure. This resulted in a final systolic leaflet position deeper within the right ventricular cavity than is normally seen. The finding was present in the following diagnostic subgroups: Group A, pulmonary hypertension (11 patients); Group B, rheumatic heart disease (4 patients); Group C, dilated cardiomyopathy (9 patients) and Group D, previous myocardial infarction (7 patients). Right atrial, right ventricular and tricuspid anulus measurements were made and compared with those from a group of 67 normal subjects. The results were as follows: right atrial endsystolic area = 27.2 +/- 8.6 cm2 (normal = 13.4 +/- 2.0); right ventricular end-systolic area = 25.6 +/- 8.7 cm2 (normal = 10.9 +/- 2.9); right ventricular end-diastolic area = 31.5 +/- 9.1 cm2 (normal = 20.1 +/- 4.9) and tricuspid valve anular end-systolic dimension = 4.0 +/- 0.6 cm (normal = 2.2 +/- 0.3). The differences from the normal data were all statistically significant (p less than 0.001). Incomplete closure of the tricuspid valve, although a nonspecific diagnostic finding, is primarily associated with right-sided chamber enlargement. Tricuspid regurgitation may be present. The mechanism could be related to geometric changes in valve apparatus dynamics secondary to right-sided cardiac enlargement and tricuspid valve anular dilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Ischemic cardiomyopathy

The term "ischemic cardiomyopathy" was used initially to describe a clinical syndrome that was indistinguishable from primary congestive cardiomyopathy but due to severe, diffuse coronary artery disease. The term has been expanded to include the larger category of myocardial disease secondary to coronary artery disease. Using this expanded definition, we have discussed the varied clinical presentations of congestive ischemic cardiomyopathy and restrictive ischemic cardiomyopathy (stiff heart syndrome and right ventricular infarction), and how the effects of ischemia on left ventricular systolic and diastolic performance may cause these varied presentations. The prognosis of any ischemic cardiomyopathy is related primarily to the degree of ventricular dysfunction and the extent of coronary artery disease. Therapy is aimed at preventing or ameliorating myocardial ischemia and halting the progression of, or even reversing, the deterioration in myocardial function.

Electrocardiographic changes associated with isolated right ventricular infarction

Isolated infarction of the right ventricle is an extremely rare entity. A patient is described with diffuse interstitial lung disease who developed ST segment elevation in inferior and anterior leads on a routine electrocardiogram and at autopsy was found to have an isolated right ventricular infarct involving approximately 70% of the right ventricular circumference without involvement of the left ventricle and septum. This case illustrates that isolated right ventricular infarction in the presence of cor pulmonale and right ventricular hypertrophy can produce an injury current in the limb and precordial leads of the electrocardiogram which mimics that seen in typical transmural infarction of the left ventricle.