Right Ventricular Dimensions Research Articles

Right ventricular dynamics during left ventricular assistance in closed-chest dogs

To determine the effects of left ventricular assist device (LVAD) support on global right ventricular (RV) systolic mechanics, 8 closed-chest, conscious, sedated dogs were studied after placement of an LVAD (left ventricle to femoral artery bypass) and implantation of 27 tantalum markers into the left ventricular and RV walls for computation of biventricular volumes and geometry. Biplane cinefluoroscopic marker images and hemodynamic parameters were recorded during transient vena caval occlusion at various levels of LVAD support. Right ventricular contractility was assessed using end-systolic elastance and preload recruitable stroke work, and the myocardial (pump) efficiency of converting mechanical energy to external work (stroke work/total pressure-volume area) was calculated. With full LVAD support, RV end-diastolic volume increased from 60 ± 15 to 62 ± 17 mL ( p < 0.002), pulmonary artery input impedance decreased from 940 ± 636 to 587 ± 347 dyne · s/cm 5 ( p < 0.007), and measurement of RV and left ventricular septal-free wall dimensions demonstrated a significant leftward septal shift ( p < 0.0005). Global RV end-systolic elastance and preload recruitable stroke work decreased from 2.4 ± 1.0 to 1.7 ± 0.7 mm Hg/mL ( p < 0.004) and 14.1 ± 3.3 to 12.1 ± 3.9 mm Hg ( p < 0.02), respectively; however, RV power output and myocardial efficiency did not change significantly ( p > 0.74 and p > 0.33, respectively). Therefore, during LVAD support, global RV contractility is impaired with leftward septal shifting, but RV myocardiol efficiency and power output are maintained through a decrease in RV afterload and an increase in RV preload.

RIGHT VENTRICULAR ASSESSMENT IN PATIENTS PRESENTING FOR LUNG TRANSPLANTATION

Chronic pulmonary disease is associated with varying degrees of cardiac dysfunction. Because of the potentially predominant effect of severe lung disease on right ventricular (RV) size and function, a reliable method to assess RV mechanics before and after lung transplantation may provide information of long-term significance and/or prognosis. Conventional invasive and non-invasive imaging methods have a number of limitations in evaluating RV function. Ultrafast computed tomographic (ultrafast CT) scanning has been shown to provide quantitative assessment of RV and left ventricular (LV) function in individuals with and without cardiac disease. Twenty-two patients presenting during evaluation for possible lung transplantation with end-stage pulmonary disease formed the basis of this study. There were 14 patients with chronic obstructive pulmonary disease and 8 with pulmonary fibrosis. Conventional transthoracic echocardiography and ultrafast CT were used for the assessment of RV and LV function. All patients had invasive assessment of right-sided hemodynamics and pulmonary function studies performed within 7-10 days of cardiac imaging. A qualitative assessment of RV size or function was possible in all but two patients by echocardiogram, but in 45%, the echocardiographic examination was described as suboptimal. In contrast, a quantitative assessment of ventricular volumes and systolic function was obtained in all patients by ultrafast CT. Pulmonary function parameters or hemodynamic measurements obtained during cardiac catheterization did not correlate with any assessment of RV function. We concluded that (1) ultrafast CT provides measurement of the RV and LV cavity dimension and systolic function; (2) invasive right-sided hemodynamics or pulmonary function studies do not predict RV function; and (3) echocardiography does not uniformly provide assessment of RV function in patients with chronic pulmonary disease.

Effects of respiration on right ventricular size and function: an echocardiographic study.

The effects of quiet respiration and body position on right ventricular (RV) size and function were assessed by two-dimensional (2DE) and M-mode echocardiography in 15 healthy children. All end-diastolic echocardiographic dimensions, areas, and volumes increased slightly but significantly with inspiration. At end-systole similar changes were found. RV ejection fractions were significantly higher during inspiration, as were stroke volume indices. RV dimensions also increased from supine to left lateral decubitus position. Thus, our results indicate a need for standardization of 2DE and M-mode measurements not only for body position, but also for respiratory phase when used to assess RV size and function.

Reevaluation of Hemodynamic Consequences of Positive Pressure Ventilation

To examine the cyclic changes in right ventricular (RV) function induced by controlled ventilation, right heart catheterization and two-dimensional echocardiography were combined in a group of 20 patients requiring respiratory support for an episode of acute respiratory failure. Simultaneous measurements of RV pressure (using a modified pulmonary artery catheter), RV stroke output (thermodilution), and RV dimensions (two-dimensional echocardiography), permitted a beat to beat evaluation of RV function throughout the mechanical respiratory cycle. When compared with expiration, lung inflation produced an increase in RV systolic pressure and volume, an increase in RV diastolic volume with an unchanged RV diastolic pressure, and a marked decrease in RV ejection fraction. It is concluded that controlled ventilation altered RV function primarily by increasing RV afterload during the lung inflation period.

CARDIOVASCULAR EFFECTS OF DILTIAZEM IN THE DOG

The effects of two bolus injections (0.2 mg kg-1) and two infusion rates (0.2 mg min-1 and 0.4 mg min-1) of diltiazem on global and regional left (LV) and right ventricular (RV) performance (ultrasonic dimension technique), on coronary (electromagnetic flow meters) and systemic haemodynamics, and on electrophysiology (PR, QRS, QTc intervals) were studied in eight open-chest dogs anaesthetized with droperidol and fentanyl. The two bolus injections of diltiazem resulted in plasma concentrations of 688 +/- 115 and 650 +/- 85 ng ml-1 (means +/- SE), respectively, and caused substantial decreases in systemic and coronary vascular resistances, and in aortic pressure, and increases in LV segment shortening, stroke volume and aortic flow. Electrophysiological variables were little affected. At the low infusion rate (plasma concentration 140 +/- 23 ng ml-1) coronary and systemic vasodilatation occurred, but global and regional RV and LV performance were little affected. PR interval increased by 15%. At the higher infusion rate (plasma concentration 282 +/- 33 ng ml-1) coronary and systemic vasodilatation were maintained. Aortic pressure decreased slightly. Whereas LV end-diastolic and end-systolic dimensions remained unchanged, they increased in the RV. In addition, the PR interval increased by 35%, and three animals developed atrioventricular block type I. The data indicate that diltiazem is a potent coronary and systemic vasodilator with little effect on global RV and LV performance. However, at a higher infusion rate RV dimensions clearly tend to increase, and conduction abnormalities develop.

Right ventricular thallium-201 visualization in hypertrophic cardiomyopathy

Fifty-six patients with hypertrophic cardiomyopathy who had echocardiography and cardiac catheterization were studied. Eleven (18%) of 56 patients had right ventricular (RV) thallium-201 visualization at resting scan. RV thallium-201 visualization was observed in the apex or lower half of the RV free wall, which was quite different from that with RV pressure or volume overload. There was no significant correlation between RV thallium-201 visualization and interventricular septal thickness or haemodynamic data. RV systolic pressure and RV dimension were within normal limits whether RV visualization was observed or not. Thus, an abnormal increase of RV mass in hypertrophic cardiomyopathy may lead to RV thallium-201 visualization without RV pressure or volume overload.

Pulmonary injury depresses cardiac systolic function through Starling mechanism.

To determine whether pulmonary microvascular injury or lung hyperinflation changes left ventricular (LV) performance and whether ventricular interaction plays a role in mediating such changes, we studied seven open-chest, closed-pericardium, anesthetized dogs before and after right ventricular (RV) injections of 150- to 200-micron glass beads. Because people with pulmonary disease are often treated with positive end-expiratory pressure, we also hyperinflated the lungs before and after creating the pulmonary microvascular injury. Measurements of LV and RV pressures and dimensions were taken at end expiration during the basal state, during lung hyperinflation, and after microvascular injury at RV end-diastolic pressures of 5, 10, and 15 mmHg produced by volume loading. Acute volume loading produced upward shifts in the LV diastolic pressure-size curve both before and after microvascular injury. Neither microvascular injury nor lung hyperinflation substantially affected the LV diastolic pressure-size relationship. LV end-diastolic size determined LV stroke work with no consistent independent influence of microvascular injury or lung hyperinflation. Neither microvascular injury nor lung hyperinflation depressed systolic performance beyond that associated with changes in end-diastolic heart size.

Usefulness of echocardiographic assessment of right ventricular and pulmonary trunk size for estimating magnitude of left-to-right shunt in children with atrial septal defect

M-mode and 2-dimensional echocardiographic studies were performed in 42 patients, aged 1 to 16 years (mean 6), with a secundum or sinus venosus type atrial septal defect (ASD) and normal pulmonary artery pressure. Twenty normal children served as a control group. In patients with ASD the echocardiographic variables were correlated with the magnitude of the left-to-right shunt (Qp/Qs) calculated by the Fick principle. Although M-mode echocardiograms showed increased right ventricular (RV) dimension in 69% of the patients, the correlation between RV dimension index (RV dimension/body surface area) and Qp/Qs was weak (r = 0.49). When RV dimension was related to left ventricular (LV) dimension and expressed by the RV/LV ratio, 90% of the patients were found to have an abnormally large right ventricle. The correlation between the RV/LV ratio and Qp/Qs was fairly good (r = 0.64). In 33 patients (78%), the pulmonary trunk (PT) was adequately visualized and measured on 2-dimensional echocardiograms. The dimension of the PT was related to the aortic root dimension and expressed by the PT dimension/aortic dimension ratio. This ratio was 0.99 ± 0.06 in normal children and 1.35 ± 0.23 in patients with ASD (p <0.001). The PT/aortic ratio exceeded the upper limit of normal (the normal mean value + 2 standard deviations) in each of the 27 patients with a Qp/Qs of 1.5 or greater. In 5 of the 6 patients with a Qp/Qs of less than 1.5 the PT/aortic ratio was close to 1 and within the normal range. An excellent correlation (r = 0.89) was found between the PT/aortic ratio and Qp/Qs. The echocardlographic determination of the RV/LV ratio and particularly the PT/aortic ratio is therefore useful in the noninvasive estimation of the left-to-right shunt in ASD.

Assessment of right heart hemodynamics by contrast echocardiography

We studied inferior vena cava contrast echocardiography after upper extremity injection in 70 subjects; 59 were patients and 11 were controls. Inferior vena cava contrast was seen in 35 patients and in 1 control. “A-wave synchronous pattern” of contrast apperance was observed in 13 patients and 1 normal subject. The pattern did not depend upon the height of right atrial a-wave pressure or the right ventricular (RV) end-diastolic pressure, but was related to the respiratory cycle. A “random pattern” of contrast appearance was seen in 3 patients with cardiac arrhythmia and normal right heart hemodynamics. One patient with ventricular premature beats showed both “a-wave synchronous” and “random” patterns. A “v-wave synchronous pattern” was found in 20 patients, of which 17 had tricuspid regurgitation. Persistence of inferior vena cava contrast correlated with the height of right atrial v-wave ( r = 0.87, p < 0.001) and the severity of tricuspid regurgitation estimated from RV cineangiography. The differences of RV systolic pressure and echocardiographic right ventricular dimension between the study patients with and without tricuspid regurgitation did not reach statistical significance. We conclude: (1) the echocardiographic RV dimension and the degree of RV hypertension are not predictors for the presence of tricuspid regurgitation and its severity; (2) inferior vena cava contrast echocardiography may be used to estimate the severity of tricuspid regurgitation.

Pulsus Alternans: Echocardiographic Evidence of Reduced Venous Return and Alternating End-diastolic Fiber Length as Causative Factors

The echocardiographic findings are described in a patient with left heart failure both before and after development of severe pulsus alternans (PA). Right ventricular dimension (RVD) before and after PA was 2.7 and 1.0 cm, respectively. Left atrial dimension (LAD) before and after PA was 4.8 cm and 2.7 cm, respectively. Left ventricular end-diastolic dimension (LVDd) without PA was 6.7 cm; with PA was 6.0 cm before the strong beat and 5.7 cm before the weak beat. End-diastolic thickness of the left ventricular wall (LVW) was 0.8 cm before the strong beat and 1.1 cm before the weak beat. Thus the weak beat was initiated from a shorter end-diastolic fiber length than the strong beat. The weak beat had no aortic valve opening, and the accompanying phonocardiogram revealed absence of the early ejection sound and aortic component of the second heart sound. Decreased blood volume owing to diuretic therapy most likely contributed to the development of PA, since the RVD, LAD, and LVDd became smaller, the heart rate did not change, and the rhythm was regular. The echocardiographic findings are described in a patient with left heart failure both before and after development of severe pulsus alternans (PA). Right ventricular dimension (RVD) before and after PA was 2.7 and 1.0 cm, respectively. Left atrial dimension (LAD) before and after PA was 4.8 cm and 2.7 cm, respectively. Left ventricular end-diastolic dimension (LVDd) without PA was 6.7 cm; with PA was 6.0 cm before the strong beat and 5.7 cm before the weak beat. End-diastolic thickness of the left ventricular wall (LVW) was 0.8 cm before the strong beat and 1.1 cm before the weak beat. Thus the weak beat was initiated from a shorter end-diastolic fiber length than the strong beat. The weak beat had no aortic valve opening, and the accompanying phonocardiogram revealed absence of the early ejection sound and aortic component of the second heart sound. Decreased blood volume owing to diuretic therapy most likely contributed to the development of PA, since the RVD, LAD, and LVDd became smaller, the heart rate did not change, and the rhythm was regular.

Effects of corrective surgery on natural history of atrial septal defect of secundum type.

Two hundred and seventy-eight patients with atrial septal defect of secundum type were operated on surgical closure of the defect. The patients were divided into 5 groups according to age at surgery, and preoperative complaints and laboratory findings were analyzed to evaluate natural history. As year passed, incidence of complaints increased. Cardiothoracic ratio (CTR), systolic pressure of the right ventricle (PRVS), end-diastolic pressure of the right ventricle (RVEDP), mean pressure of the right atrium (PRAm), ratio of pulmonary to systemic systolic pressure (PPA/PS), right ventricular dimension (RVD) and left atrial dimension (LAD) increased significantly, while frontal axis of the QRS complex, RV1, SV1 +RV5 and LVD decreased. No chronological changes were seen in ratio of pulmonary to systemic blood flow (QPA/QS) and ratio of pulmonary to systemic vascular resistance (RPA/RS). The first and second decades of life were considered to be stable stages of the disease. Postoperatively, changes in the above-mentioned parameters were compared in each age group, and effects of surgical repair on natural history were evaluated. Of 265 survivors, 168 were followed-up for more than one year, the longest period being 22 years. CTR, frontal axis, RV1, PRVS, RVEDP, PPA/PS and RVD decreased significantly, while SV1 + RV5, RPA/RS and LVD increased. No changes were seen in LAD. Surgical effects appeared most significantly in the first decade and least in the fifth or more. From these findings it would be concluded that corrective surgery should be best carried out in the first decade, at latest in the second, though not to be contraindicated by age alone. Otherwise, postoperative improvement of parameters delays or hemodynamical abnormalities may persist regardless of considerable clinical improvement.

Left-to-right shunt in atrial septal defect: Quantification by echocardiography

Time motion echocardiograms (ECHO) of 30 patients with atrial septal defect (ASD) and 36 individuals without heart disease (C) were comparatively studied to see whether parameters may be defined indicating the size of the left-to-right shunt (LRS). The diagnosis was proven by cardiac catheterization; in the patients with ASD the pulmonic-to-systemic blood flow ratios,Qp:Qs, ranged from 1.33 to 3.85:1, and pulmonary vascular resistance was normal. The ratio of the left (LVD) and right ventricular dimension (RVD), LVD:RVD, and the RVD indices of the patients with ASD were significantly different from those of the C:1.07±0.04 vs. 3.1±0.03 and 22.5±0.5 vs. 9.8±0.2 mm/m2 respectively (mean ±1 SEM),p≦0.001. These parameters and the abnormal interventricular septal motion in 84% of patients with ASD did not correlate with the size of the LRS. However, the ratioQp:Qs between 1.33 and 3.85:1 linearly correlated with the ratio derived from the maximal diastolic opening of the tricuspid (TVO) and mitral valve (MVO), TVO:MVO, with a coefficient ofr=0.76,p 1.15, while in the C TVO:MVO ranged from 0.7–1.13 with a mean of 1.02±0.01 (1 SEM). The data suggest that in patients with ASD a significant left-to-right shunt may be quantified by ECHO and that these patients may be separated either from patients with ASD and a small LRS and/or from normal subjects.

1179 ECHOCARDIOGRAPHIC EVALUATION OF RIGHT VENTRICULAR FUNCTION IN PATIENTS WITH CYSTIC FIBROSIS

Non-invasive evaluation of right ventricular (RV) function has been difficult in patients with cystic fibrosis (CF). Echographic recording of the pulmonary valve permits measurement of the phases of RV systole, and the ratio of the RV pre-ejection period to the RV ejection time (RPEP/RVET) correlates well with pulmonary artery pressure. RPEP/RVET and other echographic measurements including RV wall (RVW) and dimension (RVD) were compared with pulmonary function tests and clinical scores in 28 CF patients ranging in age from 4-35 years. RPEP/RVET correlated well with percent vital capacity (%VCA) r=-0.74, residual volume (%RVol) r=0.72, and clinical score r=-0.77. RVW and RVD correlated poorly (r<0.50) with %VCA, %RVol, and clinical score. Multilinear regression of RPEP/RVET and RVD improved correlations significantly for %RVol (r=0.82 and clinical score (r=0.84). Patients in right heart failure (RHF) exhibit significantly higher RPEP/RVET (mean 0.43) than those without RHF (mean=0.33) indicating higher pulmonary artery pressure or diminished RV contractility in patients with RHF. The use of digoxin did not significantly change this value. At the conclusion of the study satisfactory pulmonary valve echograms could be obtained in 2/3 of patients tested and success was independent of the severity of the pulmonary disease.

Assessment of cor pulmonale in cystic fibrosis by echocardiography.

Thirty-one patients with cystic fibrosis of varying severity were examined by echocardiography. Right ventricular dimension (RVD) was above upper normal limit in 14 patients and right ventricular dimension index (RVD index) was higher than the upper normal limit in 11 patients. Furthermore, there was a significant relationship between increasing RVD index and 1) decreasing forced vital capacity (FVC) both actual test results and average 6 months values; and 2) decreasing peak-expiratory flow rate (PEFR) both actual test results and average 6 months values. This observation suggests a persistent heart involvement. Five patients had either heart failure and/or electrocardiographic evidence of right ventricular abnormality. These patients had increased RVD index and one patient with the highest RVD index died 8 weeks after the examination. The present study has shown the usefulness of echocardiographic measurement of right ventricular dimension and of septal motion in assessing cor pulmonale, before development of electrocardiographic abnormalities and right heart failure.

ECHOCARDIOGRAPHIC OBSERVATIONS IN PATIENTS WITH RIGHT VENTRICULAR CONDUCTION DELAY

The echocardiographic (E) pattern of an early systolic anterior septal notch (ESASN) in post-op patients (pts) with complete right bundle branch block has been recently reported. This study evaluates the E findings in 35 pts with a right ventricular (RV) conduction delay (CD) on ECG (rsR^ pattern in VI with QRS duration ≤.08secs). 24 pre-op pts with catheterization diagnoses of secundum atrial septal defect (2°ASD) (17), normal heart (2), mild pulmonic stenosis (2), obstructed pulmonary veins (1), ventricular septal defect (1) and IHSS (1) were evaluated. In each pt, ESASN was recorded, regardless of RV dimensions or type of septal motion. The onset of ESASN after the QRS, its amplitude and duration were 84±9msec, 2.3±55mm and 114±11msec (mean±S.D.) respectively. Time intervals were corrected for heart rate using the square root of the RR interval. 11 pts were evaluated 2-7(M=3.S) years after surgical closure of a 2°ASD. In 8 of 11 pts with, and 2 of 3 pts without a residual RVCD, an identical ESASN was noted. In 20 normal pts without an RVCD, no ESASN was observed. Our observations indicate: 1) an ESASN is a characteristic pattern of septal motion associated with RVCD on ECG; 2) the occurrence of ESASN in pts with normal hearts and both systolic and diastolic overload, regardless of RV size or type of septal motion suggests a direct relationship to the ECG pattern of RVCD; 3) the presence of ESASN in pts with normal ECG after 2°ASD repair suggests that the echocardiogram may be a more sensitive indicator than the ECG for detection of residual RVCD.

Echocardiography in congenital and acquired absence of the pericardium. An echocardiographic mimic of right ventricular volume overload.

The purpose of this study was to investigate the echocardiographic effects of absence of the pericardium. Five patients with congenital complete absence of the left pericardium were studied. All had typical chest X-rays, four had cardiac catheterization which excluded any intracardiac shunts, and one had diagnostic pneumothorax. All five had an enlarged right ventricular dimension (RVD): 1.9 +/- 0.1 cm/m2 (normal: less than 1.3 cm/m2) and abnormal interventricular septal (IVS) motion (three Type A, two Type B). Sixteen additional patients were studied after pericardial stripping for a variety of conditions. In none was cardiopulmonary bypass used. Eight of these patients had preoperative echocardiograms; all showed normal IVS motion. After surgery RVD was large in all 16 patients, increasing from 1.0 +/- 0.2 cm/m2 preoperatively to 1.7 +/- 0.1 cm/m2 postoperatively, P less than 0.01. Fourteen of the 16 patients had abnormal IVS motion, nine Type A, and five Type B. We conclude that absence of the pericardium results in echocardiographic abnormalities which mimic those seen in right ventricular volume overload. This may be due to altered cardiac position and motion within the thorax resulting from loss of normal pericardial restraint.