Ventricular interdependence: significant left ventricular contributions to right ventricular systolic function

Interventricular coupling coefficients in a thick shell model of passive cardiac chamber deformation

Mechanical interplay between the adjacent ventricles is one of the principal modulators of physiopathological heart function, and the underlying mechanisms of interaction are only partially understood, hence hampering clinically useful interpretation of imaging data. In order to characterize the influence of chamber geometry on ventricular coupling, the ventricles and septum are modeled as portions of ellipsoidal shells, and configuration is derived as a function of pressure gradients by combining shell element equilibrium equations through static boundary conditions applied at the sulcus. Diastolic volume (v) surfaces are calculated as a function of pressure (p), contralateral pressure (clp) and intrathoracic pressure (p ( t )) and match literature data where available. Ventricular interaction is characterized in terms of partial derivatives in v-p-clp-p ( t ) space both under physiological and altered (selectively stiffened walls) conditions. The model allows prediction of diastolic ventricular v-p-clp-p ( t ) interplay in a variety of physiopathological circumstances.

k-t2 BLAST: exploiting spatiotemporal structure in simultaneously cardiac and respiratory time-resolved volumetric imaging

Multidimensional imaging resolving both the cardiac and respiratory cycles simultaneously has the potential to describe important physiological interdependences between the heart and pulmonary processes. A fully five-dimensional acquisition with three spatial and two temporal dimensions is hampered, however, by the long acquisition time and low spatial resolution. A technique is proposed to reduce the scan time substantially by extending the k-t BLAST framework to two temporal dimensions. By sampling the k-t space sparsely in a lattice grid, the signal in the transform domain, x-f space, can be densely packed, exploiting the fact that large regions in the field of view have low temporal bandwidth. A volumetric online prospective triggering approach with full cardiac and respiratory cycle coverage was implemented. Retrospective temporal interpolation was used to refine the timing estimates for the center of k-space, which is sampled for all cardiac and respiratory time frames. This resulted in reduced reconstruction error compared with conventional k-t BLAST reconstruction. The k-t(2) BLAST technique was evaluated by decimating a fully sampled five-dimensional data set, and feasibility was further demonstrated by performing sparsely sampled acquisitions. Compared to the fully sampled data, a fourfold improvement in spatial resolution was accomplished in approximately half the scan time.

Right ventricular dysfunction in hypertrophic cardiomyopathy as evidenced by the myocardial performance index

BACKGROUND

Left ventricular function in hypertrophic cardiomyopathy (HCM) has been extensively studied, whereas right ventricular function is much less explored. The myocardial performance index (MPI) has been shown to be useful in functional assessment of both ventricles. Furthermore, right ventricular MPI was found to be of predictive value in heart failure due to dilated cardiomyopathy and ischemic heart disease. The aim of this study was, therefore, to evaluate the right ventricular MPI in patients with HCM.

METHODS

Fifty patients with HCM and 250 healthy controls were studied by conventional Doppler echocardiography and Doppler tissue imaging.

RESULTS

Patients showed increased global, 0.48 (0.15) vs. 0.21 (0.14), and regional, 0.71 (0.23) vs. 0.55 (0.17), right ventricular MPI, as compared to controls, p<0.001. Tricuspid annular plane systolic excursion and peak myocardial systolic velocities were also reduced. Patients with dyspnoea had increased global right ventricular MPI (0.53 vs. 0.36, p<0.05) as compared to those without dyspnoea.

CONCLUSION

In the present study, patients with HCM showed evidence of both global and regional right ventricular dysfunction. Previous studies of the right ventricle in HCM have only shown evidence of diastolic dysfunction, contrary to our results, showing impairment of both systolic and diastolic function. This study suggests that HCM should not only be regarded as an isolated disease of the left ventricle, but rather as a biventricular disease. The predictive value of our findings in HCM needs to be assessed in a separate study with special reference to those with and without dyspnoea.

Left ventricular end-diastolic geometrical adjustments during exercise in endurance athletes

The increase in left ventricular (LV) end-diastolic volume has recently been shown to explain more than 70% of the increase in stroke volume during upright exercise in endurance athletes. As the end-diastolic volume enhancement not could be explained by an increase in axial cavity length an augmentation in LV short-axis diameters is to be expected. To investigate LV end-diastolic geometrical alterations during exercise, 15 endurance athletes were examined using contrast exercise echocardiography. LV end-diastolic short-axis diameters were made from apical views at several LV cavity levels. From upright rest to upright exercise the LV end-diastolic internal cavity measurements increased significantly. During exercise, the LV cavity became geometrically more spherical with the largest increase in the LV end-diastolic short-axis cavity diameters in the mid and apical parts of the left ventricle. The LV internal long axis showed significant increase from rest to exercise but the absolute increase was small.

Relationship between the tricuspid annular plane systolic excursion and right and left ventricular function in critically ill patients

OBJECTIVE

Echocardiographic recording of the tricuspid annular plane systolic excursion (TAPSE) has been recommended for assessing right ventricular function in cardiac patients. The ability of TAPSE to reflect right ventricular function at baseline and to monitor acute changes in right ventricular function was tested in critically ill patients.

DESIGN

Prospective study.

SETTING

A 24-bed medical intensive care unit.

PATIENTS

Eighty-six patients admitted for acute respiratory failure, circulatory failure, or coma.

INTERVENTIONS

In 40 patients, the examination was repeated after volume expansion (n = 15), passive leg raising (n = 5), or dobutamine infusion (n = 20).

MEASUREMENTS AND RESULTS

The right ventricular fractional area change, TAPSE, the left ventricular ejection fraction, and the ratio of right to left ventricular end-diastolic area were measured using Doppler echocardiography. In the overall population, TAPSE (19+/-5 mm) was positively related to left ventricular ejection fraction (r2 = 0.31, p < 0.001) and right ventricular fractional area change and was negatively related to age and to the ratio of right to left ventricular end-diastolic area. Multivariate analysis indicated that only left ventricular ejection fraction and age were independently related to TAPSE (multiple r2 = 0.36, p < 0.001). Following dynamic interventions, the changes in TAPSE were linearly related to changes in left ventricular ejection fraction (r2 = 0.65, p < 0.01) but notto changes in the right ventricular fractional area change.

CONCLUSIONS

Unexpectedly, TAPSE was more strongly related to left ventricular ejection fraction than to indices of right ventricular function in critically ill patients. The potential interest of TAPSE as a dynamic marker of left ventricular systolic function deserves further study.

Potential implications of the helical heart in congenital heart defects

The anatomic and functional observations made by Francisco Torrent-Guasp, in particular his discovery of the helical ventricular myocardial band (HVMB), have challenged what has been taught to cardiologists and cardiac surgeons over centuries. A literature debate is ongoing, with interdependent articles and comments from supporters and critics. Adequate understanding of heart structure and function is obviously indispensable for the decision-making process in congenital heart defects. The HVMB described by Torrent-Guasp and the potential impact on the understanding and treatment of congenital heart defects has been analyzed in the following settings: embryology, ventriculo-arterial discordance (transposition of great arteries), Ebstein's anomaly, pulmonary valve regurgitation after repair of tetralogy of Fallot, Ross operation, and other congenital heart defects. The common structural spiral feature is only one of the elements responsible for the functional interaction of right and left ventricles, and understanding the form/function relationship in congenital heart defects is more difficult than for acquired heart disease because of the variety and complexity of congenital heart defects. Individuals involved in the care of patients with congenital heart defects have to be stimulated to consider further investigations and alternative surgical strategies.

Time-dependent response of both ventricles after septal ablation: Implications for biventricular support after left ventricular assist device placement

OBJECTIVES

An ovine model of septal ablation was studied to elucidate the mechanisms involved in right ventricular failure when commencing left ventricular mechanical assistance. The disruption of ventricular interdependence after acute and chronic septal injury was examined.

METHODS

Twelve sheep underwent percutaneous transluminal septal myocardial ablation using 0.6 mL ethanol. Twelve other sheep underwent a sham procedure. Left ventricular and right ventricular pressure and volume (conductance) response 15 minutes and 4 weeks postinjury were measured. Ultrasonic crystals measured chamber dimensions and wall movement. Areas at risk and infarct zones were quantified.

RESULTS

Compared with sham, ablation chronically reduced systolic interventricular septal thickening (18.4% +/- 5.8% vs 7.3% +/- 3.1%; P < .001) and acutely increased right ventricular ejection fraction (37.6% +/- 8.5% vs 69.9% +/- 7.2%; P < .001), preload recruitable stroke work (42.0 +/- 4.4 erg x 10(3) vs 48.7 +/- 2.0 erg x 10(3), P < .001), end-systolic elastance (1.03 +/- 0.19 mm Hg mL(-1) vs 1.31 +/- 0.18 mm Hg mL(-1); P < .001), and Tau (24.9 +/- 3.8 ms vs 29.6 +/- 8.2 ms; P < .001). In contrast, for left ventricular ejection fraction (55.5% +/- 5.9% vs 38.9% +/- 7.7%; P < .001), preload recruitable stroke work (85.9 +/- 10.6 mm Hg vs 66.5 +/- 9.6 mm Hg; P < .001) and elastance (2.13 +/- 0.51 mm Hg mL(-1) vs 1.81 +/- 0.44 mm Hg mL(-1); P < .001) were reduced, but Tau increased (22.0 +/- 3.5 ms vs 28.9 +/- 5.8 ms; P < .001) and remained elevated at 4 weeks compared with sham. The area at risk was the same between groups, and injury was limited to the septum (17.2% +/- 2.7% vs 2.9% +/- 5.8%; P < .001).

CONCLUSIONS

Acute and chronic hemodynamic responses are distinctly different after septal injury; the acute response demonstrates a paradoxical motion. Resolution of this motion at 4 weeks is suggestive of reduced septal compliance and buttressing. Ventricular interactions after placement of a left ventricular assist device will vary depending on the injury duration.

Anesthetic Concerns in Lung Transplantation for Severe Pulmonary Hypertension

Lung transplantation has become a consolidated treatment for patients with severe pulmonary hypertension (PH). Several difficulties are encountered during the procedure in such candidates, who are still recognized as more severely affected by perioperative morbility and mortality than those undergoing lung transplantation for other diseases. Right ventricular (RV) enlargement with tricuspid regurgitation, small left ventricle (LV) with an asymmetric hypetrophic wall, interventricular septal shift toward the left, with ventricular stiffness and diastolic incompetence, are typical preoperative echocardiographic findings of end-stage PH. A smooth induction and tracheal intubation will help prevent hypertensive crisis in highly susceptible candidates. Uncompensated vasodilatation or myocardial depression caused by anesthetics and mechanical ventilation may be responsible for acute RV dysfunction associated with low systemic blood pressure. Resuscitation and emergency adoption of cardiopulmonary by-pass (CPB) has been described for near-fatal anesthesia induction. Cardiovascular instability can develop after institution of one-lung ventilation and pulmonary artery clamping. An acute increase in pulmonary pressure results in a decrease in RV ejection fraction and then in acute RV failure. Interdependence of the right and left ventricles occurs such that RV function can alter LV function. Early detection of impending circulatory and/or respiratory deterioration is warranted to prevent an irreversible decline in cardiac output, resulting in hazardous cardiac arrest. Inhaled nitric oxide represents the first choice for treatment of PH and RV failure associated with systemic hypotension during lung transplantation. Intraoperative situations requiring CPB must be identified before development of systemic shock, which represents a late ominous sign of RV failure.

The Impact of Hypertension and Hypertension-Related Left Ventricle Hypertrophy on Right Ventricle Function

AIM

The aim of our study is to determine the effect of hypertension and hypertension-related left ventricle hypertrophy on right ventricle (RV) morphology and function by using RV standard Doppler echocardiographic indices, myocardial Doppler imaging, and strain/strain rate imaging indices.

METHODS

We studied 35 patients with arterial hypertension and 30 age- and sex-adjusted control subjects who had no other pathological conditions. Standard transthoracic Doppler echocardiographical measurements, pulsed-wave tissue Doppler from tricuspid anulus (Peak systolic-st, peak early diastolic-et, peak late diastolic velocity-at), reconstructed spectral pulsed-wave tissue Doppler velocities (peak systolic-S, peak early-E, peak late diastolic velocity-A), and strain/strain rate imaging of RV free wall mid region (peak systolic strain-in, peak systolic strain rate-SR) were obtained.

RESULTS

Age, body surface area, blood pressure, and heart rate were comparable between two groups. Hypertensive subjects had significantly increased LV end-diastolic septal and posterior wall thickness, left atrial diameter, LV mass, LV mass index, and relative wall thickness during diastole. At the level of right ventricular lateral tricuspid annulus without systolic changes, the majority of diastolic measurements were altered in hypertensives (early diastolic velocity et; 13 +/- 2 vs. 18 +/- 4 m/sec, P < 0.0001, late diastolic velocity at; 20 +/- 4 vs. 14 +/- 3 m/sec, P < 0.0001, early to late diastolic velocity ratio; 0.69 +/- 0.14 vs. 1.32 +/- 0.38, P < 0.0001). The velocity data from two-dimensional color myocardial imaging at the level of RV free wall mid region again showed altered diastolic measurements in hypertensives (E; 8.01 +/- 2.6 vs. 10.4 +/- 3.14 m/sec, P < 0.001, A; 11.5 +/- 2.6 vs. 9.12 +/- 3.7 m/sec, P < 0.0001, E/A ratio; 0.75 +/- 0.41 vs. 1.87 +/- 0.48, P < 0.00). The peak systolic strain of RV free wall mid region was significantly lower in hypertensive individuals than controls (25.666 +/- 5.64 vs. 30.03 +/- 6.78%, P < 0.05). No significant differences were found in other parameters of RV function between hypertensive and control subjects.

CONCLUSIONS

The present study demonstrates that besides the manifest morphologic LV adaptations, significant RV functional alterations can be determined by TDI and strain/strain rate imaging in patients arterial hypertension. Both tissue velocities by TDI and strain imaging may be new tools to define and quantitate subtle change in systolic and diastolic function of right ventricular function in arterial hypertension that cannot be determined in standard echocardiographic parameters.

Biventricular myocardial adaptation to different training protocols in competitive master athletes

BACKGROUND

Conflicting data have been reported about the nature (physiologic versus pathologic) of left ventricular (LV) hypertrophy in master athletes.

AIM OF THE STUDY

To analyze LV and right ventricular (RV) myocardial function in master athletes with LV hypertrophy induced by either endurance or strength training.

METHODS

Standard Doppler echo and colour Doppler Myocardial Imaging (DMI) of LV and of RV basal lateral walls were performed in 40 competitive master (>45 years) endurance athletes (ATE), in 20 master strength-trained athletes (ATS) and 25 age-matched healthy sedentary subjects, all males. By use of DMI, the following parameters of myocardial function were assessed: systolic peak velocities, precontraction time, contraction time, early (E(m)) and late (A(m)) diastolic peak velocities, E(m)/A(m) ratio, relaxation time.

RESULTS

The two groups were comparable for age, but ATS at rest showed higher heart rate, systolic blood pressure, and body surface area. LV mass index did not significantly differ between the two groups of athletes. However, ATS showed increased wall thickness and relative wall thickness, while LV stroke volume and both LV and RV end-diastolic diameters were greater in ATE. All transmitral and transtricuspid Doppler indexes were higher in ATE. DMI analysis showed in ATE higher E(m) and E(m)/A(m) ratio at the level of both RV and LV lateral walls. In the overall population of athletes, linear regression models evidenced independent positive association of RV peak E(m) velocity with both LV stroke volume and maximal workload achieved by bicycle ergometer (both p<0.001).

CONCLUSIONS

RV early diastolic myocardial function is positively influenced by preload increase in master athletes and represents an independent determinant of cardiac performance during physical effort. Therefore, colour DMI may be taken into account to distinguish different cardiac adaptation to either endurance or strength sport training in master athletes.

Five-dimensional MRI incorporating simultaneous resolution of cardiac and respiratory phases for volumetric imaging

PURPOSE

To develop a new volumetric imaging method resolved over both the cardiac and respiratory cycles, to enable future physiological and pathophysiological studies of respiratory-related cardiac motion.

MATERIALS AND METHODS

An acquisition scheme is proposed whereby the k-space acquisition order is controlled in real-time by the current cardiac and respiratory phases. To reduce eddy-current effects induced by sudden jumps in k-space, the acquisition order is further optimized by the use of a Hilbert curve trajectory in the k(y)-k(z) plane. A complete three-dimensional (3D) k-space is acquired for all combinations of cardiac and respiratory phases, yielding a five-dimensional (5D) data set after retrospective reconstruction.

RESULTS

Left (LV) and right ventricular (RV) wall excursion was measured in a healthy volunteer. Diastolic LV diameter was shown to increase during expiration and decrease during inspiration, as expected from previous echocardiography studies. The LV volume was estimated for all cardiac and respiratory phases with the use of a fully 3D segmentation tool. The results confirmed that the diastolic LV volume increased during expiration and decreased during inspiration.

CONCLUSION

With its ability to measure motion anywhere in the heart, the described technique provides a promising approach for in-depth description of interventricular coupling, including 3D ventricular volumes, during both the cardiac and respiratory cycles.

Coupling of a 3D finite element model of cardiac ventricular mechanics to lumped systems models of the systemic and pulmonic circulation

In this study we present a novel, robust method to couple finite element (FE) models of cardiac mechanics to systems models of the circulation (CIRC), independent of cardiac phase. For each time step through a cardiac cycle, left and right ventricular pressures were calculated using ventricular compliances from the FE and CIRC models. These pressures served as boundary conditions in the FE and CIRC models. In succeeding steps, pressures were updated to minimize cavity volume error (FE minus CIRC volume) using Newton iterations. Coupling was achieved when a predefined criterion for the volume error was satisfied. Initial conditions for the multi-scale model were obtained by replacing the FE model with a varying elastance model, which takes into account direct ventricular interactions. Applying the coupling, a novel multi-scale model of the canine cardiovascular system was developed. Global hemodynamics and regional mechanics were calculated for multiple beats in two separate simulations with a left ventricular ischemic region and pulmonary artery constriction, respectively. After the interventions, global hemodynamics changed due to direct and indirect ventricular interactions, in agreement with previously published experimental results. The coupling method allows for simulations of multiple cardiac cycles for normal and pathophysiology, encompassing levels from cell to system.

Comparison of right ventricular functions by tissue Doppler imaging in patients with obstructive sleep apnea syndrome with or without hypertension

OBJECTIVE

To evaluate the right ventricular function in patients with obstructive sleep apnea syndrome (OSAS) independent from systemic hypertension (HT) and to determine the association between OSAS severity and right ventricular dysfunction.

METHODS

The study population included 77 consecutive subjects; 20 of these patients had OSAS, 20 of them had HT, but did not have OSAS, 16 patients, who constituted the study group, had both disorders, and 21 subjects without any of these two disorders represented the control group. Right ventricular function was assessed by echocardiography: standard two-dimensional, M-Mode, and conventional Doppler as well as tissue Doppler imaging. None of the patients had a previous history of cardiac disease. The diagnosis of OSAS was based on an apnea- hipopnea index of 5 or higher in polysomnography.

RESULTS

Tricuspid inflow velocities and tissue Doppler derived tricuspid annular diastolic velocities were significantly different in the patient groups (OSAS, HT, OSAS + HT) compared to the control group. Tricuspid annular plane systolic excursion (TAPSE) (18.3 +/- 3.2, 18.4 +/- 2.5, 20.1 +/- 2.1, and 20.7 +/- 2.5 mm, respectively, P = 0.024) and peak systolic myocardial velocity at tricuspid lateral annulus (S-vel) (12.2 +/- 1.5, 10.9 +/- 0.9, 11.2 +/- 1.1, and 13.1 +/- 2.1 cm/s, respectively, P < 0.001) were significantly lower in patient groups compared to those of the study group. Tissue Doppler derived myocardial performance index (MPI) of the right ventricle was significantly impaired in the patient groups compared to the control group (0.34 +/- 0.06, 0.44 +/- 0.06, 0.45 +/- 0.07, and 0.41 +/- 0.06, respectively, P < 0.001). With regard to these right ventricular functional parameters, there was no significant difference between OSAS and the other patient groups (HT and OSAS + HT). There were significant correlations both between OSAS severity and the right ventricular functions, and between diastolic and systolic parameters of the right ventricle (r = -0.45, P < 0.05).

CONCLUSION

Both right ventricular systolic and diastolic functions are impaired in patients having OSAS with or without HT. Right ventricular MPI was found to be the parameter most closely related with OSAS severity and the right ventricular subclinical dysfunction.

Right ventricular systolic function is not the sole determinant of tricuspid annular motion

Maximal tricuspid annular plane systolic excursion (TAPSE) correlates well with right ventricular (RV) function; however, little is known regarding the impact of left ventricular (LV) systolic function on TAPSE. Consequently, TAPSE was examined in 206 patients (105 men; mean age 56 +/- 17 years), and the data were analyzed with respect to RV (RV fractional area change 45 +/- 19%) and LV (56 +/- 17%) systolic function. The mean TAPSE for the population studied was 1.97 +/- 0.72 cm. Although a strong linear correlation was noted between RV fractional area change and TAPSE (r = 0.73, p <0.0001), relative differences with regard to TAPSE were also found. First, the greatest TAPSE was noted only when RV and LV systolic function were normal (2.46 +/- 0.50 cm). Second, patients with reduced RV systolic function had the smallest TAPSE (1.28 +/- 0.48 cm, p <0.0001). Third, patients with normal RV function but reduced LV systolic function had TAPSE (1.91 +/- 0.54 cm, p <0.0001) that was intermediate between that of patients with normal RV and LV systolic function and those with abnormal RV systolic function. Fourth, patients with reduced biventricular function had the smallest TAPSE (1.16 +/- 0.41 cm, p <0.0001). In conclusion, TAPSE is not only determined by RV systolic function but also appears to depend on LV systolic function. TAPSE <2.0 cm is associated with some degree of either RV or LV dysfunction, whereas a value >2.0 cm suggests normal biventricular systolic function.

Exercise-Disordered Breathing in Chronic Heart Failure

Patients with heart failure develop various ventilatory abnormalities, including reduced ventilatory reserves, increased ventilatory demands, and high work and cost of breathing. They tend to breathe with a rapid-shallow pattern, have low end-expiratory lung volumes, and may develop rhythmic oscillations in ventilation and tidal volume. These abnormalities likely contribute to exercise limitations and are associated with a worsening prognosis.

Right ventricular hypertrophy causes impairment of left ventricular diastolic function in the rat

Right ventricular (RV) pressure overload causes right ventricular hypertrophy in several types of pulmonary and congenital heart diseases. The associated cardiac dysfunction has generally been attributed to alterations in RV function. However, due to global neurohormonal adaptations and mechanical ventricular interaction left ventricular (LV) function could be affected as well.Therefore,LV function, RV function and their interaction were studied in rats with monocrotaline (MCT)-induced RV hypertrophy and control rats. MCT (30 mg/kg) was used to induce pulmonary hypertension, which resulted, after 28 days, in marked RV hypertrophy (RV-weight: control 220 +/- 15,MCT 437 +/- 34mg,p < 0.05). In Langendorff-perfused hearts with balloons inserted in both the LV and the RV, the diastolic pressure-volume relations showed increased stiffness, and relaxation was prolonged in the LV and RV in the MCT group compared to controls. In the MCT group, developed pressures were increased only in the RV. An increase of LV volume increased RV diastolic pressure to a similar extent in both groups. However, an increase in RV volume did not affect LV diastolic pressure in controls, but significantly increased LV diastolic pressure in the MCT group. LV and RV developed pressure-volume relations were not affected. Calculated circumferential end-diastolic wall stresses (sigma) were larger in the MCT group (LV-sigma: 0.55 +/- 0.02, RV-sigma: 1.94 +/- 0.30 kN/m(2), both p< 0.05 to control) compared to controls (LV-sigma: 0.34 +/- 0.06,RV-sigma: 1.23 +/- 0.46 kN/m2). In the MCT group, collagen content was increased in the LV, septum and RV compared to controls. In conclusion, structural changes of the RV and LV result in depressed LV diastolic function during RV hypertrophy.

Tricuspid annular displacement predicts survival in pulmonary hypertension

RATIONALE

Right ventricular (RV) function is an important determinant of prognosis in pulmonary hypertension. However, noninvasive assessment of the RV function is often limited by complex geometry and poor endocardial definition.

OBJECTIVES

To test whether the degree of tricuspid annular displacement (tricuspid annular plane systolic excursion [TAPSE]) is a useful echo-derived measure of RV function with prognostic significance in pulmonary hypertension.

METHODS

We prospectively studied 63 consecutive patients with pulmonary hypertension who were referred for a clinically indicated right heart catheterization. Patients underwent right heart catheterization immediately followed by transthoracic echocardiogram and TAPSE measurement.

RESULTS

In the overall cohort, a TAPSE of less than 1.8 cm was associated with greater RV systolic dysfunction (cardiac index, 1.9 vs. 2.7 L/min/m2; RV % area change, 24 vs. 33%), right heart remodeling (right atrial area index, 17.0 vs. 12.1 cm(2)/m), and RV-left ventricular (LV) disproportion (RV/LV diastolic area, 1.7 vs. 1.2; all p < 0.001), versus a TAPSE of 1.8 cm or greater. In patients with pulmonary arterial hypertension (PAH; n = 47), survival estimates at 1 and 2 yr were 94 and 88%, respectively, in those with a TAPSE of 1.8 cm or greater versus 60 and 50%, respectively, in subjects with a TAPSE less than 1.8 cm. The unadjusted risk of death (hazard ratio) in patients with a TAPSE less than 1.8 versus 1.8 cm or greater was 5.7 (95% confidence interval, 1.3-24.9; p = 0.02) for the PAH cohort. For every 1-mm decrease in TAPSE, the unadjusted risk of death increased by 17% (hazard ratio, 1.17; 95% confidence interval, 1.05-1.30; p = 0.006), which persisted after adjusting for other echocardiographic and hemodynamic variables and baseline treatment status.

CONCLUSIONS

TAPSE powerfully reflects RV function and prognosis in PAH.

The usefulness of Doppler myocardial imaging in the study of the athlete's heart and in the differential diagnosis between physiological and pathological ventricular hypertrophy

Athlete's heart is a cardiac adaptation to long-term, intensive training, which includes changes as increased ventricular cavity diameters, wall thickness and mass, produced with a degree consistent with sports activities and exercise programs. The Doppler myocardial imaging (DMI) permits characterization of the velocities of each ventricular myocardial segment by placing the sample volume at the center of the cardiac muscle. Even if the standard two-dimensional (2D) echocardiography represents an irreplaceable method in the evaluation of cardiac adaptations to physical exercise, the data currently available suggests the usefulness of DMI in the assessment of the myocardial systolic and diastolic functions of the athlete's heart. In particular, an athlete's left ventricular hypertrophy is characterized by a "supernormal" DMI pattern, with increased myocardial early-diastolic velocity. Therefore, DMI analysis in the trained subject has demonstrated interesting prospective for: (1) the differential diagnosis from pathological, both, left and right ventricular hypertrophy; (2) the prediction of cardiac performance during physical effort; (3) the evaluation of the biventricular interaction; (4) the analysis of the myocardial adaptations to various training protocols; and (5) the early identification of specific genotypes associated with cardiomyopathies. On this ground, a combined use of standard 2D echo and DMI may be taken into account for a valid noninvasive and easy-repeatable evaluation of both physiological and pathological ventricular hypertrophies.

Determinants of Recurrent or Residual Functional Tricuspid Regurgitation After Tricuspid Annuloplasty

BACKGROUND

The durability of tricuspid valve (TV) repair by annuloplasty is limited. Identification of mechanisms of recurrent or residual tricuspid regurgitation (TR) after annuloplasty is necessary to improve results of TV repair. The purpose of this study was to investigate echocardiographic determinants of mid-term outcome after TV annuloplasty.

METHODS AND RESULTS

This study consisted of 39 patients with functional TR who had echocardiography preoperatively, early postoperatively (5+/-2 days), and >1 year (20+/-6 months) after TV annuloplasty. Detailed echocardiographic measurements were performed, including TR severity, TV annular dimension, TV leaflet displacement, left ventricular (LV) function, and right ventricular (RV) function and pressures. Preoperative leaflet tethering height and area predicted early and mid-term outcome of annuloplasty. Early postoperative LV ejection fraction and TR severity influenced degree of TR >1 year after surgery. In addition, increased RV pressure was related to worse TR during late follow-up.

CONCLUSIONS

Although TV tethering is an important determinant of recurrent or residual TR, LV and RV function and pressures impact repair durability. These factors identify patients at risk for repair failure; such individuals require development of additional surgical strategies to improve results of tricuspid valve repair and close surveillance after surgery.

Simulating transient ventricular interaction using a minimal cardiovascular system model

A minimal closed-loop cardiovascular system (CVS) model has been developed that can simulate ventricular interaction due to both direct interaction through the septum and series interaction through the circulation system. The model is used to simulate canine experiments carried out to study the transient response of the left ventricle due to changes in right ventricle pressures and volumes. The model-simulated trends in left and right ventricle pressures and volumes, septum deflection and arterial flow rates are compared with the experimental results. In spite of the limited physiological data available describing the animals, the model is shown to capture all the transient trends in the experimental data. This is the first known example of a physiological model that can capture all these trends. The model is then used to illustrate the separate effects of direct and series interactions independently. This study proves the value of this modelling method to be used in conjunction with experimental data for delineating and understanding the factors that contribute to ventricular dynamics.

Prognostic use of echocardiography 1 year after a myocardial infarction

BACKGROUND

Left ventricular (LV) and right ventricular (RV) function are known predictors of morbidity and mortality after an acute myocardial infarction (MI). However, the prognostic use of a late evaluation of cardiac function after an MI remains unclear.

METHODS

We analyzed echocardiograms obtained 1 year after MI in patients with LV dysfunction at baseline (ejection fraction [EF] < or = 40%) from 291 patients enrolled in the SAVE echocardiographic substudy who did not develop heart failure (HF) or a recurrent MI during this first year. Left ventricular EF and RV fractional area change were assessed.

RESULTS

After a median follow-up of 22 months after the 1-year echocardiogram, a low LVEF (< 30%) at 1 year was associated with an increased risk of death and/or HF (hazards ratio [HR] 2.7, 95% CI 1.3-5.3). Presence of RV dysfunction was also associated with an increased risk of death (HR 8.9, 95% CI 3.5-22.1), development of HF (HR 7.1, 95% CI 3.4-15.0), and the composite end point of death or HF (HR 7.6, 95% CI 4.1-14.2). In multivariate analyses, both low LVEF and RV dysfunction remained independently predictive of the composite end point of death or HF. Patients with biventricular dysfunction were at the greatest risk of death and/or HF (HR 19.4, 95% CI 8.2-46.0) in follow-up.

CONCLUSIONS

In a stable population of survivors of MI, impaired LV and RV function at 1 year after MI are independently and additively predictive of increased risk of HF or death.

Left ventricular involvement in arrhythmogenic right ventricular cardiomyopathy - a scintigraphic and echocardiographic study

BACKGROUND

Left ventricular involvement in arrhythmogenic right ventricular cardiomyopathy (ARVC) is a common finding in autopsy studies. In clinical studies using myocardial scintigraphy, MRI and echocardiography, contradictory results have been reported. In this study, we therefore investigated a group of 15 patients with ARVC using thallium-201 (Tl) single-photon emission tomography (SPECT) and echocardiography including assessment of mitral annular motion with M-mode and pulsed tissue Doppler.

METHODS

Exercise and rest Tl-201 SPECT were performed in 15 patients with ARVC. The time from diagnosis of the disease varied from less than 1-16 years. All patients fulfilled the established diagnostic criteria for ARVC. An echocardiographic examination, including assessment of left and right ventricular motion and measurements of the mitral annulus motion with M-mode and pulsed tissue Doppler was performed in the patients and in 25 normal subjects.

RESULTS

Tl-201 uptake defects in the left ventricular myocardium were present in all except one patient (93%). The uptake defects were predominantly located to the anteroseptal and basal posterior segments. Wall motion abnormalities were seen in the same segments, and in addition to this, in the septal area. In line with this, the total amplitude and the peak systolic velocity of mitral annular motion at the septal point were significantly decreased in the patients compared with the control group.

CONCLUSIONS

Our data show that left ventricular involvement is common in ARVC. Tl-201 SPECT and echocardiographic abnormalities were seen not only in patients with long-lasting symptoms but also in asymptomatic patients and in those with short duration of symptoms.

Hemodynamic effects of inhaled nitric oxide in right ventricular myocardial infarction and cardiogenic shock

OBJECTIVES

We sought to determine whether or not inhaled nitric oxide (NO) could improve hemodynamic function in patients with right ventricular myocardial infarction (RVMI) and cardiogenic shock (CS).

BACKGROUND

Inhaled NO is a selective pulmonary vasodilator that can decrease right ventricular afterload.

METHODS

Thirteen patients (7 males and 6 females, age 65 +/- 3 years) presenting with electrocardiographic, echocardiographic, and hemodynamic evidence of acute inferior myocardial infarction associated with RVMI and CS were studied. After administration of supplemental oxygen (inspired oxygen fraction [F(i)O(2)] = 1.0), hemodynamic measurements were recorded before, during inhalation of NO (80 ppm at F(i)O(2) = 0.90) for 10 min, and 10 min after NO inhalation was discontinued (F(i)O(2) = 1.0).

RESULTS

Breathing NO decreased the mean right atrial pressure by 12 +/- 3%, mean pulmonary arterial pressure by 13 +/- 2%, and pulmonary vascular resistance by 36 +/- 8% (all p < 0.05). Nitric oxide inhalation increased the cardiac index by 24 +/- 11% and the stroke volume index by 23 +/- 12% (p < 0.05). The NO administration did not change systemic arterial or pulmonary capillary wedge pressures. Contrast echocardiography identified three patients with a patent foramen ovale and right-to-left shunt flow while breathing at F(i)O(2) = 1.0. Breathing NO decreased shunt flow by 56 +/- 5% (p < 0.05) and was associated with markedly improved systemic oxygen saturation.

CONCLUSIONS

Nitric oxide inhalation results in acute hemodynamic improvement when administered to patients with RVMI and CS.

Right ventricular myocardial dysfunction in adult patients late after repair of tetralogy of fallot

AIM OF THE STUDY

To detect in adult patients late after repair of Tetralogy of Fallot (TOF) possible correlation between myocardial parameters assessed at rest by Tissue Doppler (TD) and cardiac performance during physical effort.

METHODS

Doppler echo, treadmill test and pulsed TD of both mitral and tricuspid annulus were performed in 25 healthy subjects and in 40 adult patients who had undergone surgery for TOF at a mean age of 1.4+/-0.5 years. Exclusion criteria were echocardiographic evidence of residual pulmonary, either stenosis or regurgitation. By use of TD, the following parameters were assessed: systolic peak velocities (Sm), pre-contraction time, contraction time, early (E(m)) and late (A(m)) diastolic velocities, E(m)/A(m) ratio, relaxation time. By treadmill test, we measured: maximal heart rate (HR), systolic blood pressure (SBP), rate-pressure product, maximal workload, time duration of the exercise.

RESULTS

the two groups were comparable for left ventricular measurements and for all transmitral and transtricuspid Doppler indexes, while tricuspid ring diameter was increased in TOF. TD analysis showed in TOF lower S(m), E(m) and E(m)/A(m) ratio and prolonged PCT(m) and Rt(m) at tricuspid annulus level, despite comparable TD mitral annulus indexes. By treadmill test, TOF showed reduced time of exercise, number of METS reached and rate-pressure product. Multiple linear regression models evidenced in TOF independent positive association between tricuspid Em velocity and time of exercise (p<0.0001), achieved METS at peak effort (p<0.001) and rate-pressure product (p<0.001). An E(m) peak velocity of tricuspid annulus lower than 0.13 m/s showed 90% sensitivity and 93% specificity in identifying TOF patients unable to perform maximal exercise test.

CONCLUSIONS

despite normal Doppler parameters, adult patients late after correction of TOF showed impaired right ventricular myocardial function. In these patients pulsed TD may be taken into account as a valuable supporting tool to predict the effort response and possibly to assess long-term follow-up of cardiac functional reserve.

Right ventricular function before and after an uncomplicated coronary artery bypass graft as assessed by pulsed wave Doppler tissue imaging of the tricuspid annulus

BACKGROUND

Right ventricular (RV) function using myocardial velocities before and after a coronary artery bypass graft (CABG) is not known.

METHODS

Using pulsed wave Doppler tissue imaging, RV function was studied in 35 patients before and after CABG. Patients were followed-up for 1 year after the CABG. Myocardial velocities at the tricuspid annulus at the RV free wall were recorded from the apical 4-chamber views.

RESULTS

Both the systolic and early diastolic tricuspid annular velocities (TAV) were significantly reduced 1 month after CABG (P <.001 for both). During the follow-up period, there was no improvement in the diastolic TAV. The systolic TAV showed no improvement 3 months after CABG but recovered partially 1 year after the CABG (systolic velocities were 11.8, 8.7, 8.7 and 9.7 cm/s, the early diastolic velocities were 11.0, 8.1, 8.1 and 8.2 cm/s before and 1 month, 3 months and 1 year after the CABG, respectively). The systolic and early diastolic velocities of the interventricular septum were unchanged during the follow-up period. Unlike the right ventricle, the mitral annular systolic velocity was unchanged shortly after CABG and showed signs of improvement after 1 year (6.4, 6.9, 6.8 and 7.3 cm/s respectively before and after CABG). Patients underwent dobutamine stress echocardiography (DSE) before and 3 months after the CABG. The systolic TAV increased significantly during the DSE before CABG (11.8 vs 15.8 cm/s, P <.001). However, the increase in systolic TAV was limited during DSE 3 months after CABG (8.7 vs 9.9 cm/s, P <.05).

CONCLUSION

RV function, as assessed by TAV, decreased significantly after CABG and the changes were still evident after 1 year. The response of systolic TAV during DSE was more pronounced before CABG than after CABG.

Three-dimensional assessment of two-dimensional technique for evaluation of right ventricular function by tricuspid annulus motion

BACKGROUND

Measurement of tricuspid annulus motion (TAM) is an easy way to estimate right ventricular ejection fraction (RVEF). However the accuracy of two-dimensional (2-D) methods for analyzing the three-dimensional (3-D) structure of the tricuspid annulus has not been evaluated.

OBJECTIVE

This study evaluated the accuracy with which 2-D measurements of TAM reflect RVEF using 3-D reconstructions of the heart at end diastole (ED) and end systole (ES).

METHODS

2-D echocardiographic studies were performed on 12 subjects and used to reconstruct the RV and tricuspid annulus in 3-D at ED and ES. Measurements of TAM from medial and lateral positions on the annulus were selected from the standard echocardiographic apical four-chamber view. The minimum and maximum possible TAM values, RV volumes, and movement of the apex of the heart along the trajectory of TAM were calculated from the 3-D reconstructions.

RESULTS

TAM correlated highly with RVEF (r > or = 0.90). Values found by 2-D and 3-D techniques were not significantly different. Correcting TAM for apex motion did not improve correlation. Summation of medial and lateral TAM data increased correlation values slightly relative to lateral TAM alone. Regional aberrant contractility degraded the predictive value of TAM.

CONCLUSION

Estimation of RVEF from 2-D echo measurement of TAM is accurate, especially when medial and lateral TAM are summed, except in patients with severe apical RV dysfunction.

Right ventricular myocardial adaptation to different training protocols in top-level athletes

OBJECTIVE

The aim of this study was to analyze right ventricular (RV) myocardial function in competitive athletes with left ventricular (LV) hypertrophy induced by either endurance or strength training.

METHODS

Standard Doppler echo, maximal electrocardiogram (ECG) ergometric test, and pulsed tissue Doppler (TD) of LV mitral annulus and of RV tricuspid annulus were performed in 32 competitive endurance athletes (long-distance swimmers; ATE) and in 26 strength-trained athletes (short-distance swimmers; ATS), all males. By use of TD, the following parameters of myocardial function were assessed: systolic peak velocities (Sm), precontraction time, contraction time, early (Em) and late (Am) diastolic velocities, Em/Am ratio, and relaxation time.

RESULTS

The two groups were comparable for age, but ATS at rest exhibited higher heart rate, systolic blood pressure, and body surface area. LV mass index did not significantly differ between the two groups. However, ATS characterized increased wall thickness and relative wall thickness, whereas LV stroke volume and both LV and RV end-diastolic diameters were greater in ATE. All transmitral and transtricuspid Doppler indexes were higher in ATE, with increased E/A ratios. TD analysis demonstrated in ATE higher Em and Em/Am ratio as well as longer relaxation time both at mitral and at tricuspid annulus level. In the overall population, distinct multiple linear regression models evidenced independent positive association between RV peak Em velocity and LV end-diastolic diameter (P < 0.001) as well as independent direct correlation of the same RV peak Em velocity with both LV stroke volume and maximal workload achieved by bicycle ergometer (both P < 0.001).

CONCLUSIONS

Right ventricular early diastolic myocardial function is positively influenced by preload increase in athletes, and represents an independent determinant of cardiac performance during physical effort. Therefore, pulsed TD may be taken into account to distinguish different cardiac adaptation to either endurance or strength sport activities, and eventually to quantify RV adaptation degree to long-term training.

Effects of acute left ventricular unloading on right ventricular function in normal and chronic right ventricular pressure-overloaded lambs

OBJECTIVE

Right ventricular pressure overload occurs in several types of (congenital) heart disease, as well as in pulmonary disease. Clinical outcome in some of these patient groups might in part be related to left ventricular loading conditions. The effects of left ventricular unloading on the function of the hypertrophic right ventricle have not been studied. We aimed to study the effects of left ventricular unloading on right ventricular hemodynamics and contractility in an animal model of chronic right ventricular pressure overload.

METHODS

In lambs the pulmonary artery was chronically banded to increase right ventricular pressure to systemic levels. After 8 weeks, right ventricular contractility and hemodynamic function were assessed in these lambs, as well as in age-matched control animals, by using a combined pressure-conductance catheter in the right ventricle during baseline conditions and during complete bypass of the left ventricle.

RESULTS

In both groups acute left ventricular unloading significantly decreased left ventricular pressure to low levels while aortic pressure was maintained. In the right ventricle of the control group, both end-systolic and end-diastolic volumes increased with left ventricular unloading (P <.01) while end-systolic pressure was maintained. Cardiac output was unchanged despite decreased right ventricular contractility. In the banding group acute left ventricular unloading also decreased right ventricular contractility but increased cardiac output. During acute left ventricular unloading, diastolic stiffness was unchanged in the control group, whereas it was significantly decreased in the banding group.

CONCLUSIONS

Both in normal hearts and in hearts subject to chronic right ventricular pressure overload, acute left ventricular unloading decreases right ventricular contractility. Although no effects on cardiac output are encountered in normal hearts during left ventricular bypass, cardiac output is improved in right ventricular pressure-overloaded hearts, most likely related to improved right ventricular diastolic compliance.

Different involvement of right ventricular myocardial function in either physiologic or pathologic left ventricular hypertrophy: a Doppler tissue study

The aim of the study was to analyze right ventricular (RV) myocardial function in patients with left ventricular (LV) hypertrophy secondary to either hypertrophic cardiomyopathy (HC) or athletic endurance training. Doppler echocardiography and pulsed Doppler tissue imaging of the posterior septal wall, and mitral and tricuspid annulus were performed in 32 top-level endurance athletes (AT) and in 27 patients with HC, all men. LV mass index was comparable between the 2 groups. All transmitral Doppler indexes were higher in AT, whereas only tricuspid inflow peak E and E/A ratio were slightly decreased in the HC group. In the HC group, Doppler tissue analysis showed lower myocardial systolic and early-diastolic (Em) peak velocities, and longer time intervals at the level of all the analyzed segments, even after correction for age, heart rate, and LV mass index. Distinct multiple linear regression models revealed an independent positive association between RV peak Em velocity and LV end-diastolic diameter (beta coefficient = 0.72, P <.0001) in AT, and an independent inverse correlation of the same peak Em velocity of tricuspid annulus with septal thickness (beta = - 0.65, P <.001) in the HC group. Of interest, a RV Em peak velocity < 0.16 m/s differentiated AT and HC groups better than tricuspid Doppler (89% sensitivity and 93% specificity). In conclusion, Em RV myocardial function is positively influenced by preload increase in AT and negatively associated to increased septal thickness in patients with HC. Therefore, Doppler tissue imaging may represent a useful tool in the differential diagnosis between athlete's heart and HC, underlining the different involvement of RV myocardial function in either physiologic or pathologic LV hypertrophy.

Detection of early right ventricular dysfunction in Chagas' disease using Doppler tissue imaging

BACKGROUND

The involvement of the right ventricle (RV) in Chagas' disease is frequent. Although echocardiography plays an important role in noninvasive assessment of cardiac function, evaluation of RV is challenging because of the anatomic and functional complexity of this chamber.

METHODS

To study early functional abnormalities in the RV, we selected 18 patients with Chagas' disease, no other disease, and a normal echocardiogram; and 12 normal individuals as a control group. All participants were submitted to Doppler tissue imaging and the parameters of systolic (systolic wave and regional isovolumic contraction time) and diastolic (early and late expansion waves) function were analyzed at the level of the interventricular septum and free wall of the RV.

RESULTS

Regional isovolumic contraction time values showed a statistically significant difference between the 2 groups both in the RV free (P =.0003) and septal (P =.003) walls. With respect to diastolic function, we observed a significant difference between groups involving the early expansion wave (P =.014) and e/a ratio (P =.004) of the RV free wall.

CONCLUSION

Doppler tissue imaging proved to be useful in early detection of RV dysfunction in Chagas' disease, with potential use in risk stratification of these patients.

Indexes of diastolic RV function: load dependence and changes after chronic RV pressure overload in lambs

Diastolic function is a major determinant of ventricular performance, especially when loading conditions are altered. We evaluated biventricular diastolic function in lambs and studied possible load dependence of diastolic parameters [minimum first derivative of pressure vs. time (dP/dt(min)) and time constant of isovolumic relaxation (tau)] in normal (n = 5) and chronic right ventricular (RV) pressure-overloaded (n = 5) hearts by using an adjustable band on the pulmonary artery (PAB). Pressure-volume relations were measured during preload reduction to obtain the end-diastolic pressure-volume relationship (EDPVR). In normal lambs, absolute dP/dt(min) and tau were lower in the RV than in the left ventricle whereas the chamber stiffness constant (b) was roughly the same. After PAB, RV tau and dP/dt(min) were significantly higher compared with control. The RV EDPVR indicated impaired diastolic function. During acute pressure reduction, both dP/dt(min) and tau showed a relationship with end-systolic pressure. These relationships could explain the increased dP/dt(min) but not the increased tau-value after banding. Therefore, the increased tau after banding reflects intrinsic myocardial changes. We conclude that after chronic RV pressure overload, RV early relaxation is prolonged and diastolic stiffness is increased, both indicative of impaired diastolic function.

Association between myocardial right ventricular relaxation time and pulmonary arterial pressure in chronic obstructive lung disease: analysis by pulsed Doppler tissue imaging

This study assessed right ventricular function in chronic obstructive lung disease and pulmonary hypertension by Doppler tissue imaging. Doppler echocardiography of the right ventricle and Doppler tissue imaging of the tricuspid annulus were performed in 63 subjects: 20 healthy controls, 20 with lung disease, and 23 with both lung disease and pulmonary hypertension. Two-dimensional tricuspid systolic plane excursion was lower in patients with pulmonary hypertension than in the other 2 groups. Doppler tricuspid inflow measurements distinguished patients in both of the diseased groups from the control subjects, but they did not differentiate patients with pulmonary hypertension from those without it. The ratio of peak E-wave to peak A-wave velocities derived by Doppler tissue imaging was significantly lower and the myocardial acceleration time longer in both groups of lung disease than in the control group. Only myocardial relaxation time distinguished the 3 groups (all P <.01); a gradual increase in time occurred, with the shortest time seen in controls, a longer time in patients with chronic obstructive lung disease without pulmonary hypertension, and the longest time in patients with lung disease and pulmonary hypertension. In the overall population including subjects with at least minimal tricuspid regurgitation, myocardial relaxation time was positively related to pulmonary systolic pressure. In conclusion, Doppler tissue imaging distinguishes subsets of patients affected by lung disease with or without pulmonary hypertension and identifies patients with different levels of pulmonary artery systolic pressure.

The structure and function of the helical heart and its buttress wrapping. VII. Critical importance of septum for right ventricular function

The macroscopic structure of the right ventricle includes a transverse basal loop for the free wall, and oblique septal components, originating from the descending and ascending segments of the apical loop. Data is presented that determines why right ventricular function is related principally to intraventricular septal function, and why right ventricular failure is magnified by septal stunning caused by poor myocardial protection. The background of this architectural/functional change can explain normal right ventricular function, the relationship of right ventricular performance to pulmonary vascular resistance, experimental studies that characterize right ventricular performance after architectural free wall ablation, right ventricular disconnection, right coronary occlusion, and free wall replacement. These basic science studies are related to perioperative right ventricular performance, involving methods of myocardial protection, protamine reaction, right coronary occlusion and reperfusion, right ventricular dyskinesia, chronic aortic and mitral valve replacement (MVR) replacement, congenital heart disease, right and left ventricular assist devices (LVADs), and transplantation. The predominant focus is related to the septum and how it can be evaluated perioperatively. Septal evaluation by echocardiogram should become an essential feature during intraoperative management.

Impaired distensibility of the left ventricle after stiffening of the right ventricle

Acute and chronic alterations of right ventricular (RV) wall properties can change left ventricular (LV) performance. We investigated whether and how stiffening of the RV free wall alters LV diastolic distensibility. We used cross-circulated isolated hearts, in which the LV and RV were independently controllable. Stiffness of the RV free wall was altered by intramuscular injections of glutaraldehyde into the RV free wall after right coronary artery ligation. We measured circumferential and longitudinal regional lengths in the septum and LV free wall. During data acquisition, RV volume was held constant. After the RV free wall was stiffened by glutaraldehyde, the LV diastolic pressure-volume relation shifted upward and became steeper. Importantly, stiffening of the RV free wall increased the diastolic regional area in the septum and LV free wall under constant LV volume. The augmented regional dimensions may result in enhanced regional tension under constant LV volume and may be related to the observed increase in LV diastolic intracavitary pressure. The impaired LV diastolic distensibility by stiffening of the RV free wall may be at least partly explained by myocardial stretch, probably due to LV deformation.

Use of inhaled nitric oxide for emergency Cesarean section in a woman with unexpected primary pulmonary hypertension

PURPOSE

Use of inhaled nitric oxide (iNO) could be of importance in emergency cases of primary pulmonary hypertension (PPH) in pregnant patients during labour and delivery. iNO acts as a selective pulmonary bed vasodilator avoiding systemic hemodynamic effects due to its ease of administration. Pulmonary bed vasodilation improves right ventricular function directly and left ventricular function indirectly.

CLINICAL FEATURES

We report the case of a pregnant patient with unexpected PPH in whom an emergency Cesarean section (CS) had to be performed. PPH was diagnosed on admission as she arrived in active labour at 34 weeks gestational age. An emergency CS was performed under epidural anesthesia for breech presentation . All along labour, delivery and the first 24 hr, iNO was administered via a noninvasive ventilation device. CS was uneventful. A severe pulmonary hypertensive crisis was observed 12 hr after delivery and resolved with an increase of iNO concentration and administration of isoprenalin. The patient and baby returned home on day ten.

CONCLUSION

The ease of administration of iNO allowed the optimal control of pulmonary arterial hypertension. No interaction with epidural anesthesia was observed. Use of iNO can improve the management of urgent CS in women with unexpected PPH.

Exercise capacity in adult patients with congenitally corrected transposition of the great arteries

OBJECTIVE

To examine cardiopulmonary values, static lung function, and ejection fraction in adult patients with congenitally corrected transposition of the great arteries (CCTGA).

PATIENTS AND METHODS

41 patients who had undergone static lung function testing and cardiopulmonary exercise tests with measurements of ejection fraction were identified at the Toronto Congenital Cardiac Centre for Adults.

RESULTS

Aerobic capacity in patients with CCTGA was severely diminished, varying from 30-50% of the results achieved by healthy subjects. Normal values of right ventricular and left ventricular ejection fraction were found. However, the systemic right ventricular ejection fraction increased by 2% from rest to exercise, as opposed to the expected > 5% increase in a healthy population. The pulmonary left ventricular ejection fraction decreased by 2% at peak exercise.

CONCLUSION

Diminished values of heart rate, forced expiratory volume in one second (FEV(1)), forced vital capacity, and systolic blood pressure compared to the predicted values may contribute to the reduced maximal oxygen uptake (VO(2)max) found in patients with CCTGA. In addition, a limited increase in systolic right ventricular ejection fraction and a decrease in pulmonary left ventricle contractility suggest a dysfunction of both ventricles.

Early effects of right ventricular volume overload on ventricular performance and beta-adrenergic signaling

OBJECTIVE

Right ventricular dysfunction is a poorly understood but persistent clinical problem. This study was undertaken to evaluate ventricular performance and beta-adrenergic receptor signaling in a tricuspid regurgitation model of right ventricular overload.

METHODS

Seventeen dogs were chronically instrumented with epicardial dimension transducers. By means of the shell-subtraction model, right ventricular pressure-volume relationships were evaluated in normal and right ventricular overload states. Right ventricular chamber performance was quantified by the stroke work at an end-diastolic volume relationship.

RESULTS

Right ventricular volume overload caused a 28% +/- 11% and 31% +/- 9% decline in chamber performance acutely and at 1 week, respectively, whereas end-diastolic volume increased from 45 +/- 21 to 60 +/- 30 mL (P =. 019). beta-Adrenergic receptor signaling in myocardial samples was assessed, examining adenylyl cyclase and G-protein-coupled receptor kinase activity. Stimulated adenylyl cyclase activity significantly decreased, and G-protein-coupled receptor kinase activity significantly increased in both left and right ventricular samples caused by increased levels of beta-adrenergic receptor kinase 1. No change in beta-adrenergic receptor density was seen at 1 week.

CONCLUSIONS

Early right ventricular overload is associated with impaired right ventricular chamber contractility, dilation, and, importantly, a biventricular alteration of beta-adrenergic receptor signaling.

Right ventricular pressure and dilation during pressure overload determine dysfunction after pressure overload

Volume expansion and inotropic stimulation are used clinically to augment cardiac output during acute right ventricular (RV) pressure overload. We previously showed that a brief period of RV pressure overload causes RV free wall dysfunction that persists after normal loading conditions have been restored. However, the impact of volume expansion and inotropic stimulation on the severity of RV dysfunction after acute pressure overload is unknown. We hypothesized that the severity of RV dysfunction after RV pressure overload would be related to the level of RV free wall systolic stress during RV pressure overload, rather than to the specific interventions used to augment RV function. Chloralose-anesthetized, open-chest pigs were subjected to 1 h of RV pressure overload caused by pulmonary artery constriction, followed by 1 h of recovery after release of pulmonary artery constriction. A wide range of RV free wall systolic stress during RV pressure overload was achieved by either closing or opening the pericardium (to simulate volume expansion) and by administering or not administering dobutamine. The severity of RV free wall dysfunction 1 h after RV pressure overload was strongly and directly correlated with the values of two hemodynamic variables during RV pressure overload: RV free wall area at peak RV systolic pressure (determined by sonomicrometry) and peak RV systolic pressure, two of the major determinants of peak RV free wall systolic stress. Opening or closing the pericardium, and using or not using dobutamine during RV pressure overload, had no independent effects on the severity of RV dysfunction. The findings suggest that the goal of therapeutic intervention during RV pressure overload should be to achieve the required augmentation of cardiac output with the smallest possible increase in RV free wall systolic stress.

Right ventricular function in patients with first inferior myocardial infarction: assessment by tricuspid annular motion and tricuspid annular velocity

BACKGROUND

Unlike left ventricular function, right ventricular (RV) function has not been widely studied after a myocardial infarction (MI). The current study describes RV function determined by tricuspid annular motion and tricuspid annular velocity after MI.

METHODS AND RESULTS

Thirty-eight patients with a first acute inferior MI were prospectively compared with 33 patients with a first anterior MI and 24 age-matched healthy individuals. Association of RV infarction in inferior MI was defined as the presence of >/=1-mm ST-segment elevation at the right precordial lead, V(4)R, of the electrocardiograms. From the echocardiographic apical 4-chamber views, the systolic motion of the tricuspid annulus was recorded at the RV free wall with the use of 2-dimensional guided M-mode recordings. Peak systolic and peak early and late diastolic velocities of the tricuspid annulus at the RV free wall also were recorded with the use of pulsed-wave Doppler tissue imaging. The tricuspid annular motion was reduced in inferior MI compared with that in healthy individuals (20.5 and 25 mm, P <.001). The peak systolic velocity of the tricuspid annulus was significantly reduced in inferior MI compared with that in healthy individuals (12 vs 14.5 cm/s, P <.001) and patients with anterior MI (12 and 14.5 cm/s, P <.001). Patients with inferior MI were divided into 2 subgroups: those with and those without electrocardiographic signs of RV infarction. The tricuspid annular motion was significantly lower in patients with RV infarction than in patients without RV infarction (17 and 22.7 mm, P <.001). In addition, compared with patients without electrocardiographic signs of RV infarction, patients with RV infarction also had a significantly decreased peak systolic tricuspid annular velocity (13.3 and 10.3 cm/s, P <.001) and peak early diastolic velocity (13 and 8.2 cm/s, P <.001).

CONCLUSIONS

These results suggest that tricuspid annular motion and tricuspid annular velocity can be used to assess RV function in association with inferior MI.

Right ventricular volumes and ejection fraction with fast cine MR imaging in breath-hold technique: applicability, normal values from 52 volunteers, and evaluation of 325 adult cardiac patients

Our goal was to establish right ventricular (RV) volume and ejection fraction (EF) values in normal volunteers with fast magnetic resonance (MR) imaging using a breath-hold technique, to assess the frequency and severity of RVEF abnormality in cardiac patients and to compare RV with left ventricular (LV) data. We performed simultaneously derived RV and LV fast cine measurements in 52 normals and 325 patients with coronary artery disease (CAD), acquired valvular disease (VD), cardiomyopathy (CM), or congenital heart disease (CHD). RVEF was reduced in 31% (102) of all patients, in 50% dilated CM, 39% CHD, 34% CAD, and 22% acquired VD patients. Solitary abnormally low RVEF was found in only 15/325 (5%) of all patients, whereas combined with LVEF deterioration in 87/172 (51%) patients. RVEF reduction was mild in 64%, moderate in 25%, and severe in 11%. Although RVEF correlated significantly (r = 0.55, P < 0.001) with LVEF, the predictive value of LVEF for RVEF was low. We conclude that RV volumes can be routinely assessed with fast MRI and should be performed in addition to LV evaluation in CHD, in right-sided VD, and in all patients with an abnormal LVEF.J. Magn. Reson. Imaging 1999; 10:908-918.