Problems in ultrasonic estimates of septal thickness

Asymmetric left ventricular remodeling due to isolated septal thickening in patients with systemic hypertension and normal left ventricular masses

Early identification of left ventricular (LV) structural changes may have an impact on the outlook of patients with essential hypertension. Of 669 untreated hypertensive subjects, 496 (74%) with normal LV mass at echocardiography (< 125 g/m2) were grouped according to normal LV geometry (n = 303; 61%), asymmetric LV remodeling due to isolated septal thickening (n = 111; 22%), asymmetric LV remodeling due to isolated posterior wall thickening (n = 5; 1%), or concentric LV remodeling due to septal and posterior wall thickening (n = 77; 16%). Remodeling was defined as twice the thickness of septum or posterior wall divided by the internal diameter at end diastole > 0.45. Twenty-four-hour noninvasive ambulatory blood pressure (BP) monitoring was performed in all subjects. Compared with subjects with normal LV geometry, those with asymmetric LV remodeling due to isolated septal thickening showed increased clinic BP (158/100 vs 153/97 mm Hg, both p < 0.05), mean daytime ambulatory BP (144/95 vs 138/90 mm Hg, both p < 0.01), mean nighttime ambulatory BP (128/80 vs 122/76 mm Hg, both p < 0.01), LV mass (99 vs 89 g/m2, p < 0.001), total peripheral resistance (1,881 vs 1,562 dynes s cm-5, p < 0.01) and known duration of hypertension (5.5 vs 3.6 years, p < 0.01) and decreased stroke index (39 vs 47 ml/m2, p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of echocardiographic methods for assessment of left ventricular shortening and wall stress

M-mode echocardiographic measurement of left ventricular fractional shortening and meridional wall stress has been used extensively alone and in combination to describe left ventricular systolic function. To determine whether the improved dimensional information afforded by two-dimensional echocardiography might result in shortening and stress calculations yielding a different view of left ventricular function, we compared two-dimensional and M-mode echocardiograms in 69 subjects (19 normal, 13 with aortic stenosis, 22 with aortic regurgitation and 15 with congestive cardiomyopathy). Fractional shortening was greater with M-mode than with two-dimensional echocardiography in all subjects, especially in those with cardiomyopathy (p less than 0.05). In aortic stenosis, two-dimensional shortening, at 24 +/- 5%, was reduced (p less than 0.05 versus normal), but M-mode shortening, at 34 +/- 5%, was not. M-mode estimates of meridional stress were higher than two-dimensional values, again especially in cardiomyopathy. Two-dimensional echocardiography enabled determination of long- and short-axis ratios, circumferential stress and the ratio of circumferential to meridional stresses. Circumferential stress was elevated in aortic stenosis at 302 +/- 65 X 10(3) dynes/cm2, suggesting afterload excess as the cause for the observed reduction in two-dimensional shortening. The more spherical cardiomyopathic hearts had a meridional to circumferential stress ratio closer to 1, such that use of meridional stress alone would overestimate effective afterload. It is concluded that M-mode and two-dimensional echocardiographic analyses of left ventricular shortening and stress produce different results. Two-dimensional echocardiographic methods may enhance the assessment of ventricular function, especially in patients with aortic stenosis and cardiomyopathy.

Relative wall thickness analysis by two-dimensional echocardiography

M-mode echocardiographic relative wall thickness (RWT) has been used extensively as an index of left ventricular hypertrophy. To determine whether the more extensive tomographic sampling and enhanced spatial orientation provided by two-dimensional echocardiography (2DE) might improve the value of RWT analysis, we compared 2DE and M-mode RWT in 69 subjects (19 normals, 13 with aortic stenosis, 22 with aortic regurgitation, and 15 with congestive cardiomyopathy). M-mode results correlated relatively weakly with 2DE RWT (r = 0.62 at end diastole; r = 0.81 at end systole). End-systolic M-mode values were larger than 2DE results, while end-diastolic M-mode values were generally smaller than 2DE results (both p less than 0.001). Thus, in congestive cardiomyopathy M-mode RWT was larger than 2DE end-diastolic results and therefore failed to distinguish between cardiomyopathy, aortic regurgitation, and normals. We conclude that M-mode and 2DE analysis of RWT yield disparate results. Moreover, 2DE may enhance the value of RWT in the assessment of left ventricular hypertrophy due to volume overload and cardiomyopathy.

Echocardiographic recognition of paraseptal structures

Improved echocardiographic equipment provides detailed images of the heart and shows anatomic paraseptal structures previously not well defined. Echocardiograms were analyzed from 33 patients who later underwent cardiac transplantation, and the paraseptal structures noted were correlated with the pathologic specimens. Patterns associated with right ventricular chordae tendineae, the moderator band and the posterior papillary muscle are illustrated. Hypertrophic and fibrotic right ventricular trabeculae and left ventricular paraseptal bands are noted. These structures can be specifically sought and identified using the current generation of echocardiographs, thereby avoiding potential problems of septal definition and measurement.

Comparison of echocardiographic and autopsy measurements of cardiac dimensions in the horse

This study was initiated to determine the accuracy of M-mode echocardiography in measuring left ventricular dimensions and estimating heart weights in horses. Left ventricular free wall and interventricular septal thickness and left ventricular external and internal diameters were measured and heart weights estimated from the echocardiograms of 47 horses. Autopsy measurements of the same parameters were then recorded. Statistical comparison of the data demonstrated: (1) Systolic measurements of wall thickness more closely resembled the heart in death than the diastolic measurements; (2) good correlations existed between parameters measured echocardiographically and at autopsy, especially wall thicknesses and left ventricular external diameter (maximum r = 0.82); (3) heart weight was readily predicted from echocardiographic wall thickness regressions (maximum R-squared = 68 per cent). M-mode echocardiography demonstrated the potential for direct and accurate measurements of cardiac mass and some ventricular dimensions in the horse. The data suggested that intense rigor and exsanguination may render the autopsied heart unsatisfactory for comparative measurements when assessing techniques such as echocardiography.

The relation of age to the thickness of the interventricular septum, the posterior left ventricular wall and their ratio

We obtained echocardiographic measurements of interventricular septal and posterior left ventricular wall thickness in 100 apparently normal subjects in whom there was no evidence or history of coronary artery disease, hypertension or prolapsing mitral valve. Subjects were divided into five age groups of 20-29, 30-39, 40-49, 50-59 and 60-70 years and there were 20 subjects in each group. Measurements of interventricular septum and posterior left ventricular wall thickness were made in each subject at both mitral and sub-mitral levels at the time of Q wave inscription, and the measurements were related to body surface area. The interventricular septum increased from a median of 8.3 mm in the age group 20-29 to 11.2 mm in the group 60-70, whereas the posterior left ventricular wall increased from 7.5 mm to 9.8 mm. The difference in the medians between the groups 20-29 and 60-70 was statistically significant for both interventricular septum and posterior left ventricular wall (P less than 0.02). Our data showed that interventricular septal, posterior left ventricular wall thickness measurements and their ratio should be related to age in order to assess their significance.

Angled interventricular septum on echocardiography: anatomic anomaly or technical artifact?

An acutely angled interventricular septum has been reported to constitute a distinct two-dimensional echocardiographic geometric pattern that may permit a false M-mode echocardiographic recording of asymmetric septal hypertrophy. In light of experience suggesting that the angle between the aortic root and interventricular septum varied with the intercostal space of the transducer, 45 subjects were prospectively studied by two-dimensional and M-mode echocardiography. Parasternal long- and short-axis views were obtained from two to four intercostal spaces in each subject. Two-dimensional echographic cursor-generated M-mode echocardiograms were obtained from the long-axis views; interventricular septal and left ventricular posterior wall thickness was measured from both the two-dimensional and M-mode echocardiograms. On two-dimensional echocardiography, the angle between the aortic root and septum became more acute as a progressively lower intercostal space was used (p less than 0.001). Although no change in septal thickness was apparent, the septal thickness significantly increased as a progressively lower intercostal space was used. On M-mode echocardiography, 21 subjects (47%) demonstrated asymmetric septal hypertrophy (septal/posterior wall thickness ratio greater than 1.3) from at least one intercostal space, but this was confirmed by the two-dimensional technique in only 4 subjects (9%). Thus, a two-dimensional echocardiographic recording of an angled interventricular septum can be produced by positioning the transducer in a low intercostal space, and caution must be used in the interpretation of asymmetric septal hypertrophy on M-mode echocardiograms. Two-dimensional echocardiography is a useful means of identifying subjects with apparent asymmetric septal hypertrophy that often may be the result of a technical artifact.

Significance of high voltage QRS anterior forces in young asymptomatic adults. Evaluation by wide-angle two-dimensional echocardiography

Thirteen asymptomatic adults less than 40 years old who showed tall right precordial R waves on the ECG were examined by VCG, M-mode and two-dimensional echocardiography (2D Echo). Common causes of QRS anterior displacement, such as right ventricular enlargement or right bundle branch block, were excluded in each subject. Although each subject was normal at physical examination, 2D Echo revealed areas of left ventricular hypertrophy in eight of these 13 subjects. Four had a prevailing hypertrophy of the basal portion of the interventricular septum, three had an isolated apical hypertrophy, and one had a diffuse concentric left ventricular hypertrophy. Results were normal in five cases. 2D Echo classification was confirmed by heart catheterization findings, when available. The subjects with asymmetric septal hypertrophy showed low-voltage QRS leftward forces on the ECG and VCG. ECGs and VCGs were not useful in differentiating the subjects with atypically distributed left ventricular hypertrophy from the normals: high-voltage QRS leftward forces and T wave abnormalities were evident in some subjects of both groups. Tall right precordial R waves may constitute a marker of hypertrophic cardiomyopathy in asymptomatic young adults. 2D Echo is useful to exactly classify these subjects.

The evaluation of left and right ventricular hypertrophy in combined ventricular overload by electrocardiography: relationship with the echocardiographic data

The electrocardiographic and echocardiographic (M-mode) data were analyzed in 29 patients affected by mitral or combined mitral and aortic valve disease and with hemodynamically documented biventricular overload. No electrocardiographic parameter significantly correlated with the left ventricular internal dimension at end diastole (LVIDd), the left posterior wall (LVPW) thickness and the left ventricular mass (LV mass). A significant correlation was observed between the R/S ratio in V1 and V2, the rV1 and either the end-diastolic right ventricular internal dimension (RVIDs) or the pulmonary artery systolic pressure (PASP). The R/S ratio greater than or equal to 1 in V1 was the most sensitive among the conventional electrocardiographic criteria of right ventricular enlargement. Three groups of patients were selected on the basis of RVIDd and LV mass: Group A included nine patients with right ventricular dilatation and normal LV mass; Group B included ten patients without right ventricular dilatation and with increased LV mass; Group C included ten patients without right ventricular dilatation and with normal LV mass. The R/S ratio in V1 was significantly greater in patients in group A than in those in groups B or C. No electrocardiographic parameter was found to be significantly different between groups B and C. When only LV mass was considered (independently from RVId and PASP), no electrocardiographic parameter differentiated patients with LV mass greater than 203 g from those with LV mass less than 203 g. We conclude that in patients with biventricular overload secondary to acquired valvular disease: 1) the electrocardiographic diagnosis of left ventricular enlargement is unreliable; and 2) the R/S ratio in V1 is the most sensitive parameter to predict right ventricular enlargement or severe pulmonary hypertension.

Familial hypertrophic cardiomyopathy: vectorcardiographic findings in echocardiographically unaffected relative

The electrocardiographic and vectorcardiographic (Frank system) features of the first degree relatives of subjects with documented familial hypertrophic cardiomyopathy were analysed. A total of nine affected members and 29 relatives were examined in four families. THe subjects were considered to be affected when the septal to free posterior wall thickness ratio exceeded 1.3 at M-mode echocardiography. Four relatives had asymmetric septal hypertrophy. Among 25 relatives without evidence of asymmetric septal hypertrophy, two over 20 years and 10 under 20 years of age showed increased voltage of QRS anterior forces (Qz amplitude greater than 0.80 mV) on the orthogonal electrocardiogram. The vectorcardiographic data of the relatives under 20 years of age without evidence of asymmetric septal hypertrophy (18 subjects) were compared with those of 38 normal control subjects of comparable age range. The young relatives without disproportionate septal hypertrophy had significantly greater Qz amplitude and Q/Rz ratio than the normal control subjects. In contrast, the echocardiographic data were not significantly different. We suggest that the electrocardiographic finding of abnormal anterior forces in one or more first degree relatives of subjects with documented hypertrophic cardiomyopathy may constitute a valuable aid in ascertaining the genetic transmission of the disease and in recognising affected members without echocardiographic evidence of hypertrophic cardiomyopathy.

The echocardiographic assessment of cardiomyopathy: diagnosis, classification and problems

Two-hundred-and-sixty-three patients with cardiomyopathy were studied by M-mode echocardiography. Measurements of left ventricular cavity size, wall thickness and myocardial contraction were used to classify cardiomyopathy into "congestive" (212 patients) and "hypertrophic" (50 patients) groups; the "hypertrophic" group was further divided into asymmetric septal hypertrophy (37) and symmetric (concentric) mural thickening (13). Using clinical and electrocardiographic information as well as echocardiographic data, the latter group could then be further classified into "concentric infiltrative cardiomyopathy" (9) and "concentric hypertrophic cardiomyopathy" (4). The former either presented with signs of restriction or were known to have systemic amyloidosis; the electrocardiograph showed low voltage and myocardial contraction was impaired in advanced cases. The latter had evidence of severe left ventricular hypertrophy and resembled asymmetric septal hypertrophy clinically. Problems encountered with the echocardiographic diagnosis of congestive cardiography were mainly concerned with proper clinical interpretation of the echocardiographic data whilst technical difficulties in recording the echocardiogram and in interpretation of tracings were a common problem in hypertrophic cardiomyopathy.

Hemodynamic responses to supine exercise in children with left-sided cardiac disease

Exercise, a physiologic stress, has been used in adults to unmask abnormalities of left ventricular hemodynamics not detectable at rest. Similar data in children are not available. An evaluation was made of the feasibility, safety and value of a graded upright and supine ergometer stress test to assess exercise hemodynamics during cardiac catheterization in 21 children with left-sided cardiac disease. The catheterization technique involved the simultaneous recording of intracardiac and great vessel pressures, thermodilution cardiac index and M mode echocardiograms of the left ventricular cavity. The method appears practical and safe. Although hemodynamic responses varied among clinical groups, the lack of control data currently prevents assessment of the value of this technique for long-term management.