Usefulness of measuring right ventricular anterior wall thickness in patients with right ventricular overload using M-mode echocardiography

Right ventricular anterior wall thickness measured by M-mode echocardiography and right ventricular systolic pressure obtained by right heart catheterization were correlated in 62 patients with chronic right ventricular overload including congenital heart disease and primary pulmonary hypertension. The patients were divided into two groups; one, with right ventricular systolic pressures of 39 mmHg or less; the other, 40 mmHg or more. The following results were obtained. 1. The correlation coefficient for right ventricular anterior wall thickness and right ventricular systolic pressure was r = 0.90 (p less than 0.001), and the regression equation was y = 13.2x-1.3. 2. Right ventricular end-diastolic dimension increased significantly in both groups, but no statistically significant differences were detected between the two. Right ventricular anterior wall thickness increased significantly in the group with higher right ventricular pressures (7.1 +/- 0.5 mm vs 3.1 +/- 0.5 mm). 3. When right ventricular anterior wall thickness was more than 4.0 mm, pulmonary hypertension was detected, with a sensitivity of 97.5% and a specificity of 90.9%. In conclusion, measurements of right ventricular anterior wall thickness by M-mode echocardiography via the anterior chest wall proved to be potentially useful in predicting right ventricular systolic pressures in patients with chronic right ventricular overloads.     

Detection of atrial septal defect by right sternal border echocardiography

The atrial septum can be visualized by right sternal border 2-dimensional echocardiography (2-D echo). To evaluate the usefulness of this approach in the evaluation of atrial septal defect (ASD), 50 patients who underwent cardiac catheterization were studied by 2-D echo. Twenty-one patients (Group A) had ASD (3 ostium primum, 18 ostium secundum) and 29 (Group B) had mitral valve disease and an intact atrial septum. Subcostal and right sternal border approaches were used to visualize the atrial septum. Both approaches identified the 3 cases of ostium primum ASD; secundum ASD was identified using the subcostal approach in 11 patients and using the right sternal border approach in 13. In 15 patients the ASD was imaged at least by 1 of the 2 approaches. Two-dimensional contrast echocardiography showed a positive or negative contrast effect in 13 of 18 cases (12 with standard approaches, 11 with right sternal border approach). In all patients in Group B, the right sternal border approach showed an intact atrial septum. Thus, the right sternal border approach is a useful approach that increases the sensitivity of 2-D echo in the diagnosis of ASD.     

Increased right ventricular wall thickness on echocardiography in amyloid infiltrative cardiomyopathy

In six patients with clinically significant amyloid infiltrative cardiomyopathy, echocardiographic right ventricular anterior wall thickness was significantly increased (mean 7.5 ± 2.3 mm; range 5 to 10 mm). This finding in conjunction with the previously described abnormalities of the left ventricle (symmetric increase in wall thickness, diffuse hypokinesia, and small to normal left ventricular diastolic dimension) is consistent with the findings of a diffuse myocardial infiltrative process and should minimize confusion with constrictive pericarditis.     

Assessment of the thickness of the right ventricular free wall by magnetic resonance imaging in patients with hypertrophic cardiomyopathy.

Electrocardiogram gated magnetic resonance imaging was performed in nine healthy volunteers, in four patients with pulmonary hypertension, and in 16 patients with hypertrophic cardiomyopathy. Fifty two short axis images in diastole were examined to assess the usefulness of magnetic resonance imaging for the measurement of the thickness of the free wall of the right ventricle and the degree of hypertrophy of the right ventricular free wall in hypertrophic cardiomyopathy and pulmonary hypertension. Magnetic resonance imaging gave a clear image of 68% of the length of the right ventricular free wall, showing both the endocardial and epicardial margins. The mean (1 SD) thickness of the right ventricular free wall measured at a total of 512 points was 0.44 (0.12) cm in patients with hypertrophic cardiomyopathy, 0.29 (0.08) cm in healthy individuals, and 0.73 (0.27) cm in patients with pulmonary hypertension.     

Determination of right ventricular wall thickness in systole and diastole. Echocardiographic and necropsy correlation in 32 patients.

To show that right ventricular wall thickness (RVWT) measurements can be made with precision by echocardiography, we correlated these measurements with those obtained at necropsy in 32 terminal patients. The correlation between the echocardiographic diastolic right ventricular wall thickness (mean 4.0 +/- 1.62 mm) and the necropsy measurement (mean 4.3 +/- 1.52 mm) was good (r = 0.83) in all 32 patients with normal or increased right ventricular wall thickness at necropsy. In 19 patients without necropsy evidence of right ventricular hypertrophy (RVWT less than or equal to 4 mm), the mean diastole and systolic right ventricular wall thickness were 3.0 +/- 0.92 mm and 5.1 +/- 1.64 mm, respectively. In 13 patients with necropsy evidence of right ventricular hypertrophy (RVWT greater than or equal to 5 mm), the mean diastolic and systolic right ventricular wall thicknesses were 5.3 +/- 1.56mm and 8.2 +/- 1.88 mm, respectively. We conclude that technically satisfactory echocardiograms of the right ventricular wall thicknesses. Echocardiography can reliably estimate the diastolic wall thickness and may be helpful in the evaluation of right ventricular hypertrophy.     

Total disconnection of the right ventricular free wall: surgical treatment of right ventricular tachycardia associated with right ventricular dysplasia

Arrhythmogenic right ventricular dysplasia is a myopathy that affects the right ventricular free wall (RVFW) and gives rise to recurrent reentrant ventricular tachycardia (VT). Because the entire right ventricle is potentially arrhythmogenic, ablating a single site of VT may not eliminate the arrhythmia. We developed an operation to confine any arrhythmic activity arising from the right ventricle to that chamber: total disconnection of the RVFW from the left ventricle. We performed RVFW disconnection in two patients with refractory VT associated with arrhythmogenic right ventricular dysplasia. At least two sites or origin of morphologically distinct VT were identified in the RVFW in each patient. RVFW disconnection was carried out under normothermic cardiopulmonary bypass. An encircling incision was made along the attachment of the RVFW to the aortoventricular unit and the tricuspid annulus; the right coronary artery and its RVFW branches were left intact. Electrical activity of the two chambers became dissociated, and VT arising from the RVFW was confined to that chamber. Postoperatively, there was no clinical evidence of hemodynamic impairment (follow-up 4 months and 3 months). Left ventricular function was unchanged and right ventricular flow was maintained by atrial contraction and motion of the septum toward the RVFW during left ventricular systole. One patient had incessant right ventricular tachycardia confined to the RVFW for 3 weeks. We conclude that RVFW disconnection is feasible and applicable to patients with refractory VT originating in the diffusely diseased RVFW.     

Left ventricular radius to wall thickness ratio

Left ventricular relative wall thickness, expressed as the ratio of enddiastolic radius to wall thickness (R/Th ratio), has a constant relation with left ventricular systolic pressure in children and adults with a normal heart, subjects with physiologic forms of cardiac hypertrophy (athletes) and patients with compensated chronic left ventricular volume overload (chronic aortic regurgitation). Greatly increased values for the radius/ thickness ratio, suggesting inadequate hypertrophy, indicate a poor prognosis in patients with chronic aortic regurgitation and in those with congestive cardiomyopathy; decreased values for this ratio are found in patients with hypertrophic cardiomyopathy (inappropriate hypertrophy) and in patients with compensated aortic stenosis (appropriate hypertrophy). In patients with compensated aortic stenosis, echocardiographic measurement of the left ventricular end-diastolic radius/wall thickness ratio has been used to estimate left ventricular systolic pressure. Measurement of left ventricular relative wall thickness appears to provide diagnostic and prognostic data in patients with a broad variety of cardiac disorders.     

Increased right ventricular wall thickness in left ventricular pressure overload: echocardiographic determination of hypertrophic response of the "nonstressed" ventricle

Left ventricular hypertrophy in left ventricular pressure overload occurs in response to excessive work load imposed on the left ventricle by increased impedance to ejection. Right ventricular hypertrophy may occur in patients with these findings, but has been considered to be secondary to pulmonary hypertension. To determine the frequency of right ventricular hypertrophy and its relation to increased left ventricular wall thickness in patients with left ventricular pressure overload, right ventricular wall thickness was measured using M-mode echocardiography with two-dimensional echocardiographic guidance in 65 patients with left ventricular pressure overload; 49 patients had essential hypertension and 16 had aortic valve stenosis. These measurements were compared with data from 13 patients with "thin-walled" dilated cardiomyopathy and 20 normal subjects. Average right ventricular wall thickness in hypertensive patients (7 +/- 2 mm) and patients with aortic stenosis (6 +/- 2 mm) was significantly greater than that in normal subjects (4 +/- 1 mm) and patients with dilated cardiomyopathy (4 +/- 1 mm) who had normal left ventricular wall thickness, even though left ventricular mass was increased in all patient groups. Increased right ventricular wall thickness was present in 40 (80%) of 49 patients with hypertension and 10 (63%) of 16 patients with aortic stenosis. The magnitude of increase in right ventricular wall thickness was linearly correlated (r = 0.76, p less than 0.005) with left ventricular wall thickness, but was not associated with pulmonary hypertension. It is concluded that increased right ventricular wall thickness is common in patients with left ventricular pressure overload, is directly related to increases in left ventricular wall thickness, and is independent of right ventricular hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)     

Assessment of the thickness of the right ventricular free wall by magnetic resonance imaging in patients with hypertrophic cardiomyopathy

Electrocardiogram gated magnetic resonance imaging was performed in nine healthy volunteers, in four patients with pulmonary hypertension, and in 16 patients with hypertrophic cardiomyopathy. Fifty two short axis images in diastole were examined to assess the usefulness of magnetic resonance imaging for the measurement of the thickness of the free wall of the right ventricle and the degree of hypertrophy of the right ventricular free wall in hypertrophic cardiomyopathy and pulmonary hypertension. Magnetic resonance imaging gave a clear image of 68% of the length of the right ventricular free wall, showing both the endocardial and epicardial margins. The mean (1 SD) thickness of the right ventricular free wall measured at a total of 512 points was 0.44 (0.12) cm in patients with hypertrophic cardiomyopathy, 0.29 (0.08) cm in healthy individuals, and 0.73 (0.27) cm in patients with pulmonary hypertension.     

Effect of left ventricular volume on right ventricular end-systolic pressure-volume relation. Resetting of regional preload in right ventricular free wall

Effect of left ventricular (LV) volume on right ventricular (RV) end-systolic pressure-volume relation (ESPVR) was investigated, and the mechanism was examined from a standpoint of the alteration of RV free wall mean fiber length. Twelve cross-circulated isovolumically contracting canine hearts in which both ventricular volumes were controlled independently were used, and RV-ESPVR was determined at three different LV volume levels. At small (10.2 +/- 0.6 ml), middle (15.3 +/- 1.0 ml), and large (20.5 +/- 1.4 ml) LV volume, the slope of the RV-ESPVR was 2.63 +/- 0.13, 2.74 +/- 0.13, and 2.89 +/- 0.12 mm Hg/ml, respectively, and each value was significantly different from the others (p less than 0.01). The volume intercept (V0) of the relation (RV-V0) was significantly decreased with the increment of LV volume (RV-V0 in small, middle, and large LV volume; 3.92 +/- 0.68, 3.39 +/- 0.67, and 2.87 +/- 0.71 ml, respectively; p less than 0.01). In nine hearts, RV free wall lengths in latitudinal and meridional direction were measured at three LV volume levels when RV volume was held constant (16.1 +/- 1.1 ml). RV latitudinal end-diastolic length was significantly augmented with increasing LV volume (latitudinal length in small, middle, and large LV volume; 9.68 +/- 0.55, 9.81 +/- 0.56, and 9.92 +/- 0.55 mm, respectively). RV meridional end-diastolic length also increased significantly with increasing LV volume.(ABSTRACT TRUNCATED AT 250 WORDS)     

Right ventricular wall motion disturbance and determinants of the appearance of hemodynamic right ventricular infarction.

In order to elucidate the mechanisms of the appearance of hemodynamic right ventricular infarction (RVI), we studied right and left ventriculograms and hemodynamic findings in 52 patients with acute inferior myocardial infarction. Right ventricular wall motion disturbance (RVWMD) was detected in 69% of patient but hemodynamic RVI was observed only in 16%. Among patients with RVWMD, there was no significant difference in right ventricular ejection fraction between those with (group III) and without (group II) hemodynamic RVI, suggesting that right ventricular (RV) systolic dysfunction does not independently produce hemodynamic RVI. Right ventricular end-diastolic volume index was similar in groups II and III in spite of higher mRA in group III. The result suggested that the RV compliance of group III was decreased. Heart rate (HR) was significantly lower in group III than in group II. Not only physiologic pacing but also VVI pacing significantly improved hemodynamics in patients with hemodynamic RVI. A positive correlation between HR and cardiac index was observed (r = 0.56, p < 0.001) in patients with RVWMD. Decreased RV compliance and bradycardia were considered to be determinants of the appearance of hemodynamic RVI. Volume loading did not improve hemodynamics significantly in patients with hemodynamic RVI.     

Diastolic changes in left ventricular wall thickness studied by echocardiography.

In order to study factors influencing posterior wall thickness during diastole, echocardiograms showing the septum, mitral valve and posterior wall endocardium and epicardium in 15 normal subjects and 49 patients with heart disease were digitized. Maximum wall thickness, minimum cavity dimension and the onset of mitral valve opening are normally synchronous, and an early period of rapid wall thinning, at a peak rate of 10.7 +/- 1.7 cm/sec corresponds closely to rapid filling. In patients with ischaemic heart disease the peak rate and duration of rapid thinning were normal, but thinning preceded mitral valve opening (mean 50 msec). In 11 of 17 patients with hypertrophic cardiomyopathy the peak rate of thinning was reduced and in 2 it was increased. There was a close correlation between the peak thinning rate in this group and the peak rate of increase in dimension. In mitral stenosis peak thinning rate was frequently reduced but in some patients was normal, with the reduced rate of increase in cavity dimension maintained by reversal of septal movement. We conclude that rapid thinning is an intrinsic property of the ventricular wall which is normally associated with rapid filling, but which may be dissociated from filling by asynchronous relaxation or inflow obstruction, or may be modified by myocardial disease.     

Roles of the right ventricular free wall and ventricular septum in right ventricular performance and influence of the parietal pericardium during right ventricular failure in dogs

The roles of the right ventricular (RV) free wall and ventricular septum in RV performance were studied in the canine heart. The parietal pericardium was kept intact. Acute ischemia of the RV free wall from right coronary ligation decreased the RV stroke work index more than did that of the ventricular septum from the septal branch of the left coronary artery ligation (41 and 23%, respectively, p < 0.01). The response of the RV stroke work index to acute volume loading was also decreased. Left ventricular dysfunction was detected only with ventricular septal ischemia. Combined RV free wall and ventricular septal ischemia produced more severe and predominant RV dysfunction with disproportionate elevation of RV end-diastolic pressure. After combined ischemia, pericardiotomy improved the RV stroke work index as well as the left ventricular stroke work index (40 and 27%, respectively, p < 0.05), although the increase in RV stroke work index was greater than in left ventricular stroke work index (p < 0.05).The results of this study suggest that (1) the RV free wall has a more important role than the ventricular septum in RV performance, (2) predominant RV failure can be induced experimentally after combined RV free wall and ventricular septal ischemia, and (3) the pericardium has a restrictive effect on the damaged and dilated right ventricle.     

Echocardiographic measurement of right ventricular wall thickness in hypertrophic cardiomyopathy: relation to clinical and prognostic features

Hypertrophic cardiomyopathy is characterized by unexplained left ventricular hypertrophy. It is uncertain, however, to what extent the right ventricle is also thickened. Right ventricular hypertrophy is found at autopsy in patients who die suddenly but, until recently, systematic evaluation of right ventricular morphology has not been feasible. In this two-dimensional echocardiographic study, a total of 4 to 10 (median 7) right ventricular wall thickness measurements were made from six right ventricular views in 73 patients with hypertrophic cardiomyopathy. Forty-one normal subjects were also studied for comparison. Thirty-two (44%) of the 73 patients had right ventricular hypertrophy with at least two of the wall thickness measurements exceeding 2 standard deviations (SD) from the mean value in the normal subjects. Right ventricular hypertrophy was mild (less than or equal to 8 mm) in 24 patients, moderate (9 to 12 mm) in 7 and severe (greater than 12 mm) in 1. The coefficient of variation of right ventricular wall thickness measurements was similar in normal subjects and patients with and without right ventricular hypertrophy (17 +/- 7, 11 +/- 8 and 10 +/- 8, respectively). The hypertrophy was concentric, with a coefficient of variation of 25% in all but one patient. There was a strong correlation of maximal right and mean left ventricular wall thickness (r = 0.643, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of M-mode echocardiographic measurement of right ventricular wall thickness obtained by the subcostal and parasternal approach in children

Right ventricular (RV) wall thickness was measured from M-mode echocardiograms at end-diastole from both the parasternal and subcostal approaches in 50 children of various body surface areas (0.24 to 1.68 m2). The measurements were obtained from M-mode recordings generated from sector scans to ensure precise location and position. Twenty-three children had normal hearts, and 27 had various congenital heart defects that may be associated with RV hypertrophy. Corresponding measurements of the RV wall thickness at end-diastole from the 2 approaches were similar. Subcostal echocardiographic measurement of RV wall thickness was found to be a reliable alternative to parasternal measurement in children with normal hearts and in those with congenital heart disease and RV hypertrophy.