Left Atrial To Aortic Root Ratio Research Articles

N-terminal pro–B-type natriuretic peptide levels in normotensive and hypertensive dogs with myxomatous mitral valve disease stage B

BackgroundSystemic hypertension affects the heart, and to the best of our knowledge, no study has investigated the effects of N-terminal pro-B-type natriuretic peptide (NT-proBNP) in dogs with myxomatous mitral valve disease (MMVD) stage B and systemic hypertension. This study aimed to investigate the blood level of NT-proBNP and assess the selected echocardiographic variables in dogs with MMVD stage B according to the presence of systemic hypertension or normal blood pressure and in dogs without MMVD.ResultsThe study group comprised 37 dogs with stage B MMVD (normotensive group, n = 30; systemic hypertension group, n = 7) and 13 dogs without MMVD. We evaluated NT-proBNP, blood pressure, complete blood count (CBC), and serum chemistry in all 50 dogs. We performed electrocardiography, radiography, and echocardiography on 44 dogs (37 dogs with MMVD and 7 dogs without MMVD). The NT-proBNP concentrations showed significant intergroup differences (p < 0.001). Normotensive dogs with MMVD stage B (median [interquartile range]: 1083.5 [574.8–1912.8] pmol/L) and hypertensive dogs with MMVD stage B (2345.0 [1812.5–2533.0] pmol/L) showed significantly higher NT-proBNP concentrations than dogs without MMVD (504 [430–774] pmol/L, p = 0.009 and p < 0.001, respectively), and dogs in the systemic hypertension group showed significantly higher NT-proBNP concentrations than those in the normotensive group (p = 0.046). Mitral valve regurgitation velocity was significantly higher in dogs in the systemic hypertension group (6.11 [6.07–6.24] m/s) than in those in the normotensive group (5.53 [5.17–5.95] m/s, p = 0.006). The left atrial to aortic root ratio (LA/Ao), E-peak velocity, and left ventricular end‐diastolic internal diameter corrected for body weight (LVIDDN) were significantly lower in dogs without MMVD than in dogs with MMVD stage B.ConclusionsThese findings suggest that NT-proBNP concentrations are higher in dogs with MMVD stage B with systemic hypertension than in normotensive dogs with MMVD stage B. Therefore, clinicians should be aware that NT-proBNP could be elevated in the presence of systemic hypertension.

Association of Paraoxonase-1 and NT-proBNP with Clinical, Clinico-Pathologic and Echocardiographic Variables in Dogs with Mitral Valve Disease

The objective of the present study was to measure the concentration of Paraoxonase-1 (PON-1) and N-terminal-prohormone-B-type natriuretic peptide (NT-proBNP), in the serum of dogs with degenerative Mitral Valve Disease (MVD), in order to identify their association with the clinical stage and specific clinico-pathologic and echocardiographic findings.Eighty dogs diagnosed with MVD and staged according to the ACVIM (American College of Veterinary Internal Medicine) consensus statement (B1, B2, C and D), based on their clinical, radiographic, and echocardiographic findings, were included in the study. NT-proBNP was measured only in stage B1 and B2 dogs. Clinical stage did not have a significant effect on PON-1 concentrations (p = 0.149), but NT-proBNP levels were lower in B1 dogs (p = 0.001). A significant correlation between PON-1 and total plasma proteins (p = 0.001), albumin (p = 0.003) and white blood cell count (p = 0.041) was detected, whereas there was no significant correlation (p = 0.847) between PON-1 and NT-proBNP concentrations. PON-1 showed a significant but weak negative correlation with normalized left ventricular internal diameter at diastole (LVIDdn) (p = 0.022) and systole (LVIDsn) (p = 0.012), as well as mitral valve E to A wave velocity ratio (MV E/A) (p = 0.015), but not with Left Atrial to Aortic root ratio (LA/Ao) (p = 0.892) or fractional shortening (FS%) (p = 0.944). PON-1 seems to be an insensitive marker of clinical stage and disease severity in MVD, but can be indicative of some clinico-pathological and echocardiographic changes. NT-proBNP changes are independent of oxidative stress.

Dietary intervention reduces left atrial enlargement in dogs with early preclinical myxomatous mitral valve disease: a blinded randomized controlled study in 36 dogs

BackgroundMyxomatous mitral valve disease (MMVD), the most common naturally-occurring heart disease in dogs, is associated with alterations in energy metabolism, oxidative stress and inflammation. Energy deprivation plays a causal role in the development of heart failure. This study was designed to determine if a cardiac protection blend (CPB) of nutrients containing medium-chain triglycerides as an alternative energy source, fish oil to reduce inflammation, antioxidants, and other key nutrients important to cardiac health and function could slow or prevent MMVD progression. Nineteen dogs with early stage MMVD and 17 breed-, age-, and sex-matched healthy dogs were enrolled for a 6-month blinded, placebo-controlled study. Dogs in each cardiac health group were randomly assigned to either control diet (CON) or CPB-supplemented diet. Echocardiography was performed at baseline, 3 months and 6 months.ResultsNo changes were found in healthy dogs. While MMVD-CON dogs had an average 10% increase over baseline in left atrial diameter (LAD) and left atrial to aortic root ratio (LA/Ao) at 6 months, MMVD-CPB dogs showed 3% decreases, resulting significant diet by time interactions (P = 0.037, P = 0.005, respectively). More MMVD-CON dogs progressed from stage B1 to B2 during the study. A positive correlation was found between 6-month changes in LAD and blood pressures in MMVD-CPB dogs (systolic: P = 0.050, diastolic: P = 0.035) but not MMVD-CON dogs.ConclusionsOur results demonstrated efficacy of CPB-based dietary intervention in reducing LA size and mitral regurgitation, and in slowing or preventing the progression of early MMVD in dogs.

Left atrial anteroposterior diameter in dogs: reference interval, allometric scaling, and agreement with the left atrial-to-aortic root ratio.

Left atrial enlargement (LAE) is a well-known negative prognostic factor in dogs with myxomatous mitral valve disease (MMVD). Left atrial-to-aortic root ratio (LA/Ao) is the most commonly used method to evaluate left atrial (LA) size in dogs, while the left atrial anteroposterior diameter (LAD) has been proposed as an additional measurement of LA size in different species. The aim of this study was to establish a normal reference range of LAD normalized to body weight (LADn) in dogs using allometric scales, and to evaluate the agreement between LADn and LA/Ao in the detection of LAE in dogs with MMVD. This was a retrospective, multicenter, observational study. We included 330 healthy dogs, 30 dogs with MMVD in ACVIM stage B1, 30 dogs in ACVIM stage B2, and 30 dogs in ACVIM stage C. The reference range for the LAD, depending on body weight, was between 16.91 mm and 49.68 mm. The reference range for the LADn in healthy dogs was between 10.49 and 15.72. LADn was significantly greater in dogs with MMVD compared to healthy dogs, and a significant difference in LADn was noted between different ACVIM stages (P<0.001). The most accurate cut-off value of LADn to differentiate between dogs in groups B2 and C was 20.3 (sensitivity, 83.3%; specificity, 83.3%). There was a misclassification rate of 37% between LADn and LA/Ao in the detection of LAE in group B1. This study provides a normal reference range for LAD in dogs, which can be used as an additional tool to assess LAE in dogs with MMVD.

Prostaglandin E2 and patent ductus arteriosus in premature infants

Background Patent ductus arteriosus (PDA) is a congenital heart disease most commonly occurring in premature infants. Spontaneous ductus arteriosus (DA) closure in premature infants has been suggested to be associated with duct lumen maturity and the DA sensitivity to prostaglandin E2 (PGE2).Objective To assess for a possible correlation between serum PGE2 levels and PDA size in premature infants.Methods This observational study using repeated measurements on premature infants with PDA detected at days 2-3 of life was undertaken in Cipto Mangunkusumo Hospital and Fatmawati Hospital, Jakarta, from April to May 2014. The PDA was diagnosed using 2-D echocardiography and PGE2 levels were measured by immunoassay. Pearson’s correlation test was used to evaluate a possible correlation between PGE2 level and DA diameter.Results Thirty-three premature infants of median gestational age 31 (range 28-32) weeks and median birth weight 1,360 (range 1,000-1,500) grams were enrolled. Almost two-thirds of the subjects were male. Almost all (30/33) subjects had spontaneous DA closure before the age of 10 days. Subjects’ mean DA diameter was 2.9 (SD 0.5) mm with maximum flow velocity of 0.2 (SD 0.06) cm/sec, and left atrial-to-aortic root ratio (LA/Ao) of 1.5 (SD 0.2). Their mean PGE2 levels at the ages of 2-3, 5-7, and after 10 days were 5,238.6 (SD 1,225.2), 4,178.2 (SD 1,534.5), and 915.2 (SD 151.6) pg/mL, respectively. The PGE2 level at days 2-3 was significantly correlated with DA diameter (r = 0.667; P &lt; 0.001), but not at days 5-7 (r = 0.292; P = 0.105) or at day 10 (r = 0.041; P = 0.941).Conclusion There is a strong, positive correlation between the PGE2 level and DA diameter in preterm infants at 2-3 days of age. However, there is no significant correlation between PGE2 level and persistence of PDA.

Quantitative, Noninvasive Assessment of Patent Ductus Arteriosus Shunt Flow by Measuring Proximal Isovelocity Surface Area on Color Doppler Mapping in Very Low-Birth-Weight Infants.

Background Our goal was to evaluate the hemodynamic status of very low-birth-weight infants (VLBWIs) with patent ductus arteriosus (PDA) by measuring the vena contracta width (VCW) and effective shunt orifice area (ESOA) using the proximal isovelocity surface area (PISA) on color Doppler imaging. Method and Results In this study, 34 VLBWIs with PDA (median weight: 949 g) were studied. We measured VCW and ESOA using the PISA on echocardiography. PDA-VCW was measured at the narrowest PDA flow region. ESOA determined using PISA (PDA-ESOA) was defined as the hemispheric area of laminar flow with aliased velocities on color Doppler flow imaging: PDA-ESOA = 2π (PDA radius) 2 × aligning velocity/PDA velocity. Of the 34 VLBWIs, 26 received indomethacin (IND) for symptomatic PDA. Comparing echocardiographic parameters between infants who did versus did not receive IND, significant differences were seen in the left atrial-to-aortic root ratio (LA/AO), PDA-VCW, and PDA-ESOA. Receiver operating characteristic curve analysis to differentiate between IND usage status produced statistically significant results for PDA-VCW (area under the curve [AUC] = 0.880), PDA-ESOA (AUC = 0.813), and LA/AO (AUC = 0.769). Conclusion PDA-VCW and PDA-ESOA may allow noninvasive assessment of PDA severity, and are useful when determining the timing of clinical decision making for IND administration.

Diagnostic Value of Selected Echocardiographic Variables to Identify Pulmonary Hypertension in Dogs with Myxomatous Mitral Valve Disease

BackgroundPulmonary hypertension (PH) is commonly associated with myxomatous mitral valve disease (MMVD). Because dogs with PH present without measureable tricuspid regurgitation (TR), it would be useful to investigate echocardiographic variables that can identify PH.AimTo investigate associations between estimated systolic TR pressure gradient (TRPG) and dog characteristics and selected echocardiographic variables.Animals156 privately owned dogs.Materials and MethodsProspective observational study comparing the estimations of TRPG with dog characteristics and selected echocardiographic variables in dogs with MMVD and measureable TR.ResultsTricuspid regurgitation pressure gradient was significantly (P < .05) associated with body weight corrected right (RVIDDn) and left (LVIDDn) ventricular end‐diastolic and systolic (LVIDSn) internal diameters, pulmonary arterial (PA) acceleration to deceleration time ratio (AT/DT), heart rate, left atrial to aortic root ratio (LA/Ao), and the presence of congestive heart failure. Four variables remained significant in the multiple regression analysis with TRPG as a dependent variable: modeled as linear variables LA/Ao (P < .0001) and RVIDDn (P = .041), modeled as second order polynomial variables: AT/DT (P = .0039) and LVIDDn (P < .0001) The adjusted R 2 ‐value for the final model was 0.45 and receiver operating characteristic curve analysis suggested the model's performance to predict PH, defined as 36, 45, and 55 mmHg as fair (area under the curve [AUC] = 0.80), good (AUC = 0.86), and excellent (AUC = 0.92), respectively.Conclusion and Clinical ImportanceIn dogs with MMVD, the presence of PH might be suspected with the combination of decreased PA AT/DT, increased RVIDDn and LA/Ao, and a small or great LVIDDn.

Prevalence and prognostic importance of pulmonary hypertension in dogs with myxomatous mitral valve disease.

BackgroundPulmonary hypertension (PH) is common in dogs with myxomatous mitral valve disease (MMVD) but its effect on clinical outcome has not been investigated.Hypothesis/objectivesThe presence of PH worsens the outcome in dogs with MMVD. To compare survival times of dogs with MMVD and PH to those without PH.AnimalsTwo hundred and twelve client‐owned dogs.MethodsCase review study. Medical records of dogs diagnosed with ACVIM stage B2 and C MMVD between January 2010 and December 2011 were retrospectively reviewed. Long‐term outcome was determined by telephone interview or from the medical record. End of the observation period was March 2013. PH was identified if tricuspid regurgitation peak velocity was >3 m/s.ResultsTwo hundred and twelve were identified. Eighty‐three dogs (39%) had PH. PH was more commonly identified in stage C compared to B2 (P < .0001). One hundred and five (49.5%) dogs died during the observation period. Median survival time for the entire study population was 567 days (95% CI 512–743). Stage C (P = .003), the presence of PH (P = .009), left atrial to aortic root ratio (LA/Ao) >1.7 (P = .0002), normalized left‐ventricular end‐diastolic diameter (LVEDn) >1.73 (P = .048), and tricuspid regurgitation pressure gradient (TRPG) >55 mmHg (P = .009) were associated with worse outcomes in the univariate analyses. The presence of TRPG >55 mmHg (HR 1.8 95% CI 1–2.9; P = .05) and LA/Ao > 1.7 (HR 2 95% CI 1.2–3.4; P = .01) remained significant predictors of worse outcome in the multivariate analysis.Conclusions and Clinical ImportanceIn dogs with MMVD, moderate to severe PH worsens outcome.

Prognostic value of left atrial function in dogs with chronic mitral valvular heart disease.

BackgroundA strong correlation between left atrial (LA) dysfunction and the severity of cardiac disease has been described in human patients with various cardiac diseases. The role of LA dysfunction in dogs with chronic mitral valvular heart disease (CMVHD) has not been addressed.ObjectivesTo investigate the correlation between LA function and the prognosis of dogs with CMVHD.AnimalsThirty‐eight client‐owned dogs with CMVHD.MethodsProspective clinical cohort study. Dogs were divided into 2 groups (survivors and nonsurvivors) based on the onset of cardiac‐related death within 1 year. Physical examination and echocardiographic variables were compared between the groups. For the assessment of the comparative accuracy in identifying patients with cardiac‐related death, receiver operating characteristic (ROC) curves and multivariate logistic analysis were used.ResultsThe highest accuracy was obtained for the LA active fractional area change (LA‐FAC act), with an area under the ROC curve (AUC) of 0.95, followed by the left atrial to aortic root ratio (LA/Ao), with an AUC of 0.94; peak early diastolic mitral inflow velocity (E), with an AUC of 0.85; and LA total fractional area change (LA‐FAC total), with an AUC of 0.85. In the multivariate logistic regression analysis, LA‐FAC act emerged as the only independent correlate of cardiac‐related death within 1 year (odds ratio = 1.401, P = .002).Conclusions and Clinical ImportanceRegarding both the size and function, the LA has a strong correlation with the prognosis of dogs with CMVHD. The most significant independent predictor of mortality in this study was LA‐FAC act.

Quantitative, noninvasive assessment of patent ductus arteriosus shunt flow by measuring proximal isovelocity surface area on color Doppler imaging.

We evaluated the hemodynamic status of patent ductus arteriosus (PDA) by measuring vena contracta width (VCW) and effective shunt orifice area (ESOA) using proximal isovelocity surface area (PISA) on color Doppler imaging. METHODS AND RESULTS: Study subjects were 21 patients with PDA (mean age, 3.6 years). We measured VCW (mm/m(2)) and ESOA (cm(2)) by the PISA method using echocardiography. Color images were obtained from parasternal long-axis views. VCW (mm/m(2)) was measured at the narrowest region of PDA flow. ESOA by PISA (PDA-ESOA) was defined on color Doppler flow imaging as a hemispheric area of laminar flow with aliased velocities [PDA-ESOA (cm(2))=2π[PDA radius (cm)]^2×aligning velocity (cm/s)/PDA peak velocity (cm/s)]. Upon examining the relationships with catheterization parameters by univariate analysis, VCW correlated with diastolic blood pressure (DBP), % left ventricular end-diastolic volume (%LVEDV), pulmonary blood flow index, pulmonary blood flow/systemic blood flow ratio (Qp/Qs), left-right (LR) shunt ratio, left atrial to aortic root ratio (LA/AO), chest-thoracic ratio and N-terminal pro-brain natriuretic peptide (NTproBNP); and PDA-ESOA correlated with DBP, Qp/Qs, average pulmonary artery pressure, pulmonary/systemic pressure ratio, %LVEDV, LR shunt ratio, LA/AO and NTproBNP. When stepwise multiple linear regression analysis was performed with the correlations that were significant on univariate analysis, significant correlations with Qp/Qs were noted (VCW; R(2)=0.836, β=0.914, P<0.001, PDA-ESOA; R(2)=0.621, β=0.788, P<0.001). Measurement of VCW and PDA-ESOA by the PISA method can noninvasively evaluate the hemodynamic status of PDA.

Serum Serotonin Concentration Is Associated with Severity of Myxomatous Mitral Valve Disease in Dogs

The neurotransmitter serotonin (5-hydroxytryptamine, 5-HT) has recently been suggested to play a role in the development of naturally acquired myxomatous mitral valve disease (MMVD) in dogs. To investigate the association between serum 5-HT concentration and MMVD severity in dogs, and to assess potential associations between serum 5-HT concentrations and dog characteristics, echocardiographic variables, heart rate, systolic blood pressure, presence of macrothrombocytosis, and plateletcrit. A total of 120 client-owned dogs. Dogs were prospectively recruited and were classified by standard echocardiography into healthy (dogs of breeds predisposed to MMVD, but without echocardiographic evidence of the disease), mild, moderate, or severe MMVD groups. Serum 5-HT concentrations were analyzed using an ELISA. Dogs with severe MMVD had lower serum 5-HT concentrations than healthy dogs (P = .0025) and dogs with mild MMVD (P = .0011). Unilinear and multiple regression analyses showed that serum 5-HT concentrations decreased with increasing left atrial to aortic root ratio (LA/Ao), were higher in Cavalier King Charles Spaniel (CKCS) dogs compared to dogs of other breeds, and were higher in female dogs than in male dogs. The LA/Ao was the variable most strongly associated with serum 5-HT concentration. The finding of higher serum 5-HT concentrations in dogs of breeds predisposed to the early onset of MMVD (CKCS) and dogs with mild MMVD suggests that alterations in 5-HT signaling might play a role in progression of early stages of MMVD.

Radial and Longitudinal Strain and Strain Rate Assessed by Speckle‐Tracking Echocardiography in Dogs with Myxomatous Mitral Valve Disease

Assessment of left ventricular (LV) function using conventional echocardiographic methods is difficult in mitral regurgitation (MR) owing to altered hemodynamic loading conditions. Newer methods such as speckle-tracking echocardiography (STE) provide assessment of LV strain (St) and strain rates (SR). Global St and SR are 1) decreased in dogs with clinical signs of congestive heart failure (CHF) due to myxomatous mitral valve disease (MMVD) compared with clinically healthy dogs, and are 2) associated with conventional echocardiographic indices of MMVD severity. The study subjects were 93 privately owned dogs with different MMVD severities. Prospectively recruited dogs were grouped according to MMVD severity based on echocardiographic evaluation of MR and presence of clinical signs. Global radial and longitudinal St, SR, and indices of LV dyssynchrony were assessed. On group-wise comparisons, dogs with CHF had increased global longitudinal St, global longitudinal and radial SR in systole (SRs), and early diastole (SRe) compared with dogs with no or minimal MR (all P < .04). On multiple regression analyses, these global STE variables increased with degree of MR, but associations with left atrial-to-aortic root ratio (LA/Ao) were best described by second-order polynomial equations. Thus, curvilinear relationships were found for LA/Ao and longitudinal St, SRs, and SRe (all P < .002) and radial St and SRe (all P < .001). Assessed by STE, LV function appeared to be augmented in moderate-to-severe disease. However, at CHF stages with greatly enlarged atria, a decrease to levels comparable to dogs with no or minimal MR was observed.

Survival Characteristics and Prognostic Variables of Dogs with Mitral Regurgitation Attributable to Myxomatous Valve Disease

There are few studies evaluating the natural history and prognostic variables in chronic mitral valve disease (CMVI) in a heterogeneous population of dogs. To estimate survival and prognostic value of clinical and echocardiographic variables in dogs with CMVI of varying severity. Five hundred and fifty-eight dogs belonging to 36 breeds were studied. Dogs were included after clinical examination and echocardiography. Long-term outcome was assessed by telephone interview with the owner. The mean follow-up time was 22.7 +/- 13.6 months, and the median survival time was 19.5 +/- 13.2 months. In univariate analysis, age>8 years, syncope, HR>140 bpm, dyspnea, arrhythmias, class of heart failure (International Small Animal Cardiac Health Council), furosemide therapy, end-systolic volume-index (ESV-I)>30 mL/m(2), left atrial to aortic root ratio (LA/Ao)>1.7, E wave transmitral peak velocity (Emax)>1.2 m/s, and bilateral mitral valve leaflet engagement were associated with survival time when all causes of death were included. For the cardiac-related deaths, all the previous variables except dyspnea and EDV-I>100 mL/m(2) were significantly associated with survival time. Significant variables in multivariate analysis (all causes of death) were syncope, LA/Ao>1.7 m/s, and Emax>1.2 m/s. For cardiac-related death, the only significant variable was LA/Ao>1.7. Mild CMVI is a relatively benign condition in dogs. However, some clinical variables can identify dogs at a higher risk of death; these variables might be useful to identify individuals that need more frequent monitoring or therapeutic intervention.

Severity of the ductal shunt: a comparison of different markers

Background: When the ductus arteriosus (DA) is patent, the ductal shunt is proportional to the ratio of left ventricular output (LVO) to systemic blood flow. Systemic blood flow can be...

Effects of benazepril in the treatment of feline hypertrophic cardiomyopathy Results of a prospective, open-label, multicenter clinical trial

To evaluate the efficacy of benazepril on clinical signs and echocardiographic parameters in cats with primary hypertrophic cardiomyopathy (HCM). ACE-inhibitors have positive effects in man with HCM, and contribute to a reduction of myocardial hypertrophy. Addition of an ACE-inhibitor to the standard treatment of HCM in cats may have beneficial effects. A total of 32 cats which were either asymptomatic or in stabilised congestive heart failure (ISACHC* class Ib, II or IIIa) were included in a one-year, prospective, open-label, clinical trial in 5 centres in Switzerland. 28 of these cats were allocated to one of two treatment groups: 1) standard therapy (ST) alone (n=9), consisting of a long-acting formulation of diltiazem (6-9 mg/kg sid) and optional acetylsalicylic acid (50 mg twice weekly, or 2) the same ST plus benazepril (0.33 - 0.75 mg/kg sid, n=19). Cats treated with benazepril showed a statistically significant decrease (mean +/- SEM, 0.11 +/- 0.03 mm/month, p = 0.002) in the left ventricular wall thickness (LVWD) from baseline, while no change (increase of 0.02 +/- 0.04 mm/month, p=0.66) was observed in cats on ST alone. Differences in LVWD between the two groups reached statistical significance (p=0.02). Benazepril treated cats showed more improvement in clinical signs (20-53%) than cats receiving ST alone (0-20%) but differences between the groups were not statistically significant (p>0.1). No change in septal thickness (IVSD) or left atrial to aortic root ratio (LA/Ao) was observed in either group. Benazepril had some beneficial effects on clinical signs and cardiac remodelling in cats with HCM and was well tolerated. These results, however, need to be confirmed in additional controlled studies. * ISACHC classification is described in the previous paper (Bench-study).

Echocardiographic Characteristics of Premature Infants with Patent Ductus Arteriosus

As part of a multicenter collaborative study, M-mode echocardiograms were obtained shortly after birth on 3,559 premature infants with birth weight ≤1,750 g. Of these infants, 1,496 did not develop a cardiac murmur or other signs of a "hemodynamically significant" patent ductus arteriosus (PDA). Echocardiographic parameters from this "normal" group were compared with results obtained from 415 infants in whom PDA was diagnosed on the basis of clinical findings alone, irrespective of the echocardiogram (PDA group). The best discrimination between the two groups, when considering a single parameter, was provided by a left atrial to aortic root ratio (LA/AO) of 1.40, a left ventricular to aortic root ratio (LV/AO) of 2.10, or a left ventricular systolic time interval ratio (LPEP/LVET) of 0.27. Multivariate analysis demonstrated that better separation between the two groups occurred when the left atrial to aortic root ratio and the left ventricular systolic time interval ratio were considered jointly. Because of a large degree of overlap of all echocardiographic variables between the normal group and the group with PDA, the echocardiogram alone was not a good indicator of PDA. However, when used in conjunction with a priori estimates of the probability of PDA (based, for example, on birth weight and degree of respiratory disease), use of echocardiographic data was found to improve the detection of hemodynamically significant patent ductus arteriosus in premature infants.

NON-INVASIVE ESTIMATION OF LEFT TO RIGHT SHUNTS USING ECHOCARDIOGRAMS AND RADIONUCLIDE ANGIOCARDIOGRAPHY

Echocardtography (echo) has been used in children with ventricular septal defects (VSD) to estimate the magnitude of left to right shunt (Qp/Qs) and has been correlated with Qp/Qs measured by Fick method using assumed oxygen consumption (VO2). The purpose of this study was to compare echo determined left atrial to aortic root ratio (LA/Ao) and radionuclide angiocardiography (RN) in assessing QP/Qs. Twenty three patients were studied with echo. Nine also had RN and area-ratio analysis of the radioisotope pulmonary dilution curve. These were then compared to Fick Qp/Qs using measured VO2 We found the LA/Ao to be poorly correlated with the Qp/Qs regardless of shunt size (r=0.51). However, the RN area ratios significantly correlated to Fick Qp/Qs (r=0.93). Thus we conclude that the LA/Ao is not accurate for estimation of magnitude of left to right shunt whereas RN aren ratios provide a better method for estimating Qp/Qs.