Relation of left ventricular shape to volume and mass in patients with minimally symptomatic chronic aortic regurgitation

Role of Echocardiography in the Diagnostic Assessment and Etiology of Heart Failure in the Elderly—Opacify, Quantify, and Rectify

Echocardiography offers comprehensive, noninvasive, and relatively inexpensive tools for diagnosing cardiac pathology in the elderly. With an organized approach using two-dimensional echocardiography and Doppler echocardiography, clinicians can determine the systolic and diastolic left ventricular performance; estimate the cardiac output, pulmonary artery, and ventricular filling pressures; and identify surgically correctable valve disease. Meanwhile, real-time three-dimensional echocardiography provides unprecedented volume data to quantify the left ventricular status. Tissue Doppler-derived myocardial velocity and strain imaging data provide extremely fine details about the regional variations in myocardial synchrony and predict responders to cardiac resynchronization therapy. Thus, echocardiographic tools provide the basis for determining when to attempt to rectify the left ventricular dysfunction with strategically placed, biventricular pacemaker leads.

Role of echocardiography in the diagnostic assessment and etiology of heart failure in the elderly--opacify, quantify, and rectify

Echocardiography offers comprehensive, noninvasive, and relatively inexpensive tools for diagnosing cardiac pathology in the elderly. With an organized approach using two-dimensional echocardiography and Doppler echocardiography, clinicians can determine the systolic and diastolic left ventricular performance;estimate the cardiac output, pulmonary artery, and ventricular fill-ing pressures; and identify surgically correctable valve disease.Meanwhile, real-time three-dimensional echocardiography provides unprecedented volume data to quantify the left ventricular status. Tissue Doppler-derived myocardial velocity and strain imaging data provide extremely fine details about the regional variations in myocardial synchrony and predict responders to cardiac resynchronization therapy. Thus, echocardiographic tools provide the basis for determining when to attempt to rectify the left ventricular dysfunction with strategically placed, biventricular pace-maker leads.

Left ventricular remodeling with age in normal men versus women: novel insights using three-dimensional magnetic resonance imaging

Echocardiographic left ventricular (LV) wall thickness increases with age, suggesting LV hypertrophy. However, autopsy studies have shown no change, or even a decrease, in LV mass with age. With many pathologies, LV remodeling results in changes in ventricular shape. Age-associated LV shape change might explain this discrepancy, although this has not been studied. Magnetic resonance imaging (MRI) was used in 336 healthy, normotensive adults (mean age 56 +/- 18 years; 200 women, 136 men) to measure LV mass, end-diastolic LV wall thickness, length, diameter, and shape. Echocardiographic LV mass was measured in a subset of 86 subjects by a standard algorithm. In women, LV wall thickness increased by 14% (r = 0.19, p <0.02), whereas LV length decreased by 9% (r = -0.26, p = 0.0006); LV diameter was unchanged. Thus, LV mass did not vary with age (r -0.04, p = 0.06) and the sphericity index decreased (r = -0.165, p <0.05). In men, LV wall thickness and diameter were unrelated to age, but there was an 11% decrease in LV length (r = -0.29, p = 0.003); therefore, there was an 11% decrease in LV mass (r = -0.20, p = 0.019) and a decrease in the sphericity index (r = -0.218, p <0.04). No change occurred in echocardiographic LV mass with age in either gender, although echocardiographic LV wall thickness increased in both. The left ventricle becomes more spherical with age in normal adults due to reduced LV length. In women, increased LV wall thickness offsets the decreasing LV length, whereas in men, LV wall thickness fails to compensate, resulting in decreased LV mass with age.

Impact of vascular adaptation to chronic aortic regurgitation on left ventricular performance

BACKGROUND

This investigation was designed to test the hypothesis that vascular adaptation occurs in patients with chronic aortic regurgitation to maintain left ventricular (LV) performance.

METHODS AND RESULTS

Forty-five patients with chronic aortic regurgitation (mean age 50+/-14 years) were studied using a micromanometer LV catheter to obtain LV pressures and radionuclide ventriculography to obtain LV volumes during multiple loading conditions and right atrial pacing. These 45 patients were subgrouped according to their LV contractility (Ees) and ejection fraction values. Group I consisted of 24 patients with a normal Ees. Group IIa consisted of 10 patients with impaired Ees values (Ees <1.00 mm Hg/mL) but normal LV ejection fractions; Group IIb consisted of 11 patients with impaired contractility and reduced LV ejection fractions. The left ventricular-arterial coupling ratio, Ees/Ea, where Ea was calculated by dividing the LV end-systolic pressure by LV stroke volume, averaged 1.60+/-0.91 in Group I. It decreased to 0.91+/-0.27 in Group IIa (P<0.05 versus Group I), and it decreased further in Group IIb to 0.43+/-0.24 (P<0.001 versus Groups I and IIa). The LV ejection fractions were inversely related to the Ea values in both the normal and impaired contractility groups (r=-0.48, P<0.05 and r=-0.56, P<0.01, respectively), although the slopes of these relationships differed (P<0.05). The average LV work was maximal in Group IIa when the left ventricular-arterial coupling ratio was near 1.0 because of a significant decrease in total arterial elastance (P<0.01 versus Group I). In contrast, the decrease in the left ventricular-arterial coupling ratio in Group IIb was caused by an increase in total arterial elastance, effectively double loading the LV, contributing to a decrease in LV pump efficiency (P<0.01 versus Group IIa and P<0.001 versus Group I).

CONCLUSIONS

Vascular adaptation may be heterogeneous in patients with chronic aortic regurgitation. In some, total arterial elastance decreases to maximize LV work and maintain LV performance, whereas in others, it increases, thereby double loading the LV, contributing to afterload excess and a deterioration in LV performance that is most prominent in those with impaired contractility.

Difference in the diastolic left ventricular wall motion velocities between aortic and mitral regurgitation by pulsed tissue Doppler imaging

We evaluated the difference in the diastolic left ventricular (LV) wall motion velocity between chronic isolated aortic and mitral regurgitation (AR and MR, respectively) by recording subendocardial motion velocity patterns at the middle site of the LV posterior wall in the parasternal (along the short axis) and apical (along the long axis) long-axis views of the left ventricle with pulsed tissue Doppler imaging. We studied 33 patients with AR and 35 with MR, showing moderate to severe regurgitation, and 34 healthy controls (C). The end-diastolic LV dimension along the short axis was greater in the AR and MR groups than in the C group, and that along the long axis was greater in the AR group than in the MR and C groups. There were no significant differences in percent LV fractional shortening along the short axis among the 3 groups, whereas that along the long axis was significantly smaller in the AR group than in the MR and C groups. The peak early diastolic wall motion velocity (Ew) and the time to Ew from the aortic component of the second heart sound (S2 -Ew) along the long axis were significantly lower and longer, respectively, in patients with AR than in the 2 other groups. The Ew and S2 -Ew along both the short and long axes were significantly higher and shorter, respectively, in patients with MR than in the 2 other groups. The peak early diastolic velocity of the transmitral flow correlated positively with Ew along the short axis in all patients with AR and correlated positively with Ews along the long and short axes in all patients with MR. In conclusion, early diastolic LV filling was associated with expansion of the LV wall along the short axis but with decreased excursion along the long axis in patients with AR, whereas that in patients with MR was associated with expansion of the LV wall along both the long and short axes. Pulsed tissue Doppler imaging was useful for evaluation of diastolic LV function along the long and short axes in patients with diastolic LV volume overload.

Mechanisms for left ventricular systolic dysfunction in aortic regurgitation: importance for predicting the functional response to aortic valve replacement

To test the hypothesis that the combined use of the time-varying elastance concept and conventional circumferential stress-shortening relations would elucidate differential mechanisms for left ventricular systolic dysfunction in severe, chronic aortic regurgitation and therefore predict the functional responses to aortic valve replacement, 31 control patients and 37 patients with aortic regurgitation were studied. The studies included micromanometer left ventricular pressure determinations, biplane contrast cineangiograms under control conditions and radionuclide angiograms under control conditions and during methoxamine or nitroprusside infusions with right atrial pacing. The patients with aortic regurgitation were classified into three groups: Group I had normal Emax and stress-shortening relations, Group II had abnormal Emax but normal stress-shortening relations and Group III had abnormal Emax and stress-shortening relations. The left ventricular end-diastolic and end-systolic volumes showed a progressive increase and the ejection fraction showed a progressive decrease from Group I to III; these values differed from those in the control patients (p less than 0.001). In Group I, there was a decrease in left ventricular volumes (p less than 0.05) but no significant change in ejection fraction (61 +/- 7% versus 63 +/- 4%) after aortic valve replacement. In contrast, in Group II, reduction in left ventricular volumes (p less than 0.01) was associated with an increase in ejection fraction from 50 +/- 8% to 64 +/- 11% (p less than 0.01). Finally, in Group III, reduction in left ventricular volumes (p less than 0.05) was associated with a further decrement in ejection fraction from 35 +/- 13% to 30 +/- 13%. Group I patients had compensated adequately for chronic volume overload. However, Group II had left ventricular dysfunction that was associated with an increase in the left ventricular volume/mass ratio compared with that in the control patients and Group I (p less than 0.05 for both), suggesting inadequate hypertrophy and assumption of spherical geometry. Finally, irreversible myocardial dysfunction had supervened in Group III. In conclusion, a combined analysis of left ventricular chamber performance using the time-varying elastance concept and myocardial performance using conventional circumferential stress-shortening relations provides complementary information that elucidates differential mechanisms for left ventricular systolic dysfunction and therefore predicts the functional response to aortic valve replacement.

Differences in the shape of the normal, cardiomyopathic, and volume overloaded human left ventricle

A transformation from the normal elliptical shape of the left ventricle that may accompany various disease states and that may be indicative of myocardial remodeling, has not been completely addressed in part because of the need for a descriptor of shape that is independent of chamber size. Accordingly, the goal of this study was twofold: to derive dimensionless echocardiographic descriptors of left ventricle chamber shape that are independent of chamber volume and to use these descriptors to quantitatively compare the shape of left ventricles that were either of normal size (81 +/- 17 ml, 19 patients) or were enlarged secondary to idiopathic cardiomyopathy (194 +/- 61 ml, 46 patients) or chronic aortic or mitral valve incompetence (196 +/- 67 ml, 14 patients). Two-dimensional and M-mode determined descriptors of left ventricle shape based on its width, length, and area were found to be independent of left ventricle volume. These descriptors were significantly greater in cardiomyopathy compared with the normal or dilated left ventricle secondary to valvular incompetence, indicating that the left ventricle had become nearly spherical. A spherical shape of the left ventricle was not observed with valvular incompetence. The ability to classify a patient as having either a normal or a cardiomyopathic left ventricle by discriminant function analysis was enhanced when both left ventricle size and shape were considered. In a prospective study using discriminant function and fractional shortening, we found that patients with valvular incompetence could be classified as having either a normal discriminant function and fractional shortening, an abnormal discriminant function and normal fractional shortening, or an abnormal discriminant function and fractional shortening.(ABSTRACT TRUNCATED AT 250 WORDS)

Noninvasive assessment of myocardial dysfunction in patients with chronic aortic regurgitation

Chronic aortic regurgitation may have minimal symptoms until severe myocardial dysfunction is apparent. Multiple preoperative indicators of postoperative prognosis have been sought. It appears that an elevated left ventricular end systolic dimension on echocardiography or elevated end systolic volume on radionuclide ventriculography in combination with depressed LV function and substantially increased calculated systolic wall stress may present an indicator for aortic valve replacement. Response of ejection fraction to stress may not be as reproducible, but when combined with a depressed resting ejection fraction may also be an indicator for aortic valve replacement. Even patients with severely depressed left ventricular ejection fraction may improve with surgery; however, the risks of a poor postoperative outcome is substantial increased. Appropriate management of a patient with chronic aortic regurgitation requires monitoring of multiple parameters during the patient's clinical course for optimal timing of valve replacement surgery.