Preoperative Echocardiographically Derived Mean dP/dTic Predicts Early Post-operative Dysfunction in Children Undergoing Mitral Valve Surgery

doi:10.21203/rs.3.rs-4189631/v1

Background

Mean dP/dt_ic is a quantitative measurement of ventricular function that can be obtained noninvasively by echocardiography. In adults with mitral regurgitation (MR) it has been shown to be a more sensitive predictor of post-operative left ventricular ejection fraction (EF). The utility of dP/dt_ic in pediatric congenital heart diseases with MR has been underexplored.

Methods

Patients (0 to ≤ 19 years) with MR who underwent mitral valve (MV) repair or replacement from 2015 to 2021 were included. Echocardiographically derived mean dP/dt_ic, Tei index, and EF were used to assess and compare ventricular function prior to, shortly after, and late after MV surgery.

Results

Study cohort included 61 patients (age 4.5 [IQR 0.14, 18.7] years, 89% MV repair, 11% MV replacement). Median time intervals between surgery and preoperative, early postoperative, and late postoperative echocardiograms were 6 days, 6 days, and 350 days, respectively. Median EF was 62% (z-score − 0.40) preoperatively, 56% (z-score − 1.40) early postoperatively, and 61% (z-score − 0.60) late postoperatively. Median dP/dt_ic was 1393 (IQR 1029, 1775) mmHg/s preoperatively, 1178 (IQR 886, 1946) mmHg/s early postoperatively, and 1270 (IQR 791, 1765) mmHg/s late postoperatively. Preoperative median dP/dt_ic correlated with early and late postoperative EF. Preoperative EF was not significantly correlated with early postoperative EF, but was correlated with late postoperative EF.

Conclusions

Mitral valve intervention in pediatric patients is associated with an initial decline but long-term recovery of systolic function. Non-invasively derived mean dP/dt_ic may offer advantages over other preoperative echocardiographic indices to predict postoperative systolic function.

mitral regurgitation

pediatric heart disease

echocardiography

Patients with chronic mitral regurgitation (MR) often develop left ventricular (LV) dysfunction over time secondary to the chronic volume overload imposed upon the LV by this lesion. This development has adverse prognostic implications. LV dysfunction is recognized by the American Heart Association (AHA) as an indication for surgical intervention for MR.¹ Surgical repair or replacement of the mitral valve usually prevents further deterioration of LV function in adults without congenital heart disease (CHD), but recovery of function is not routinely observed.^2–5 It is possible that children are more resilient than their adult counterparts and that improvement in LV function would be more consistently observed.⁶

Assessment of LV function in the setting of significant MR is not straightforward. An incompetent mitral valve permits the LV to eject some of its blood into the low-pressure left atrium (LA). This form of afterload reduction will cause an increase in left ventricular ejection fraction (LVEF) unrelated to a change in the LV’s contractile state. As such, the AHA recommends mitral valve (MV) surgery in adults when the LVEF is ≤ 60%, 10 percentage points higher than that recommended for aortic valve intervention. MR also causes LV volume overload (increased preload) which also may affect the LVEF and other measures of ventricular function.²

A variety of echocardiographic parameters have been proposed to detect subclinical LV dysfunction preoperatively in asymptomatic patients and may predict outcomes and dysfunction following mitral valve surgery. In adults, echocardiographically determined preoperative mean dP/dt_ic was found to be a better predictor of postoperative dysfunction than preoperative LVEF.⁷ This may be because it possesses properties that render it ideal for the assessment of ventricular function. Moreover, the mean dP/dt_ic approximates and closely correlates with the (invasively measured) peak dP/dt. Similarly the echcoardiographically determined Tei index, has also been shown to be a sensitive metric to identify patients at risk for systolic dysfunction after mitral valve repair.^8,9

Assessment of LV function in pediatric patients with CHD and MV pathology is more challenging. The anatomic variations and segmental wall motion abnormalities encountered in patients with CHD may render the geometric assumptions required for the estimation of LVEF from standard two-dimensional (2D) echocardiography unreliable. Moreover, patients with CHD who have had multiple surgical procedures often have poor acoustic windows which may make accurate visualization of endocardial borders difficult and further compromise attempts to quantitatively assess LV function. Hence, in children under consideration for MV surgery, a more robust assessment of LV function beyond a reliance solely on LVEF seems warranted. The main purpose of this study was therefore to determine whether a more comprehensive assessment of LV function prior to surgery using noninvasive echocardiographic derived indices of mean dP/dt_ic and the Tei index in addition to LVEF provides useful clinical insights.

This was a single-center, retrospective cohort study. The Institutional Review Board (IRB-P00041058) approved the study and the requirement for individual informed consent was waived. The authors are solely responsible for the design and conduct of this study, all analyses, the drafting and editing of the paper, and its final contents.

Study Population

All patients (age 1 month to ≤ 19 years) who underwent surgical repair or replacement for MR at Boston Children's Hospital between September 2015 and April 2021 were screened for eligibility. Inclusion criteria required the availability of a preoperative echocardiogram (0–9 months prior to surgery) and at least one available early postoperative echocardiogram (0–6 weeks after surgery). If an additional postoperative echocardiogram was available 5 months to 2.5 years after surgery, it was also analyzed and considered to be the late postoperative study. When multiple echocardiographic studies were available for a given time interval, the earliest echocardiogram within that time interval was used. Patients with concomitant surgical procedures that may affect ventricular function (e.g., coronary artery surgery, endocardial fibroelastosis resection, other valvular surgery, pacemaker implantation, Fontan palliation, left ventricular outflow tract surgery or right ventricular outflow tract surgery) were excluded. Other secondary surgeries such as ventricular and atrial septal defect repairs were allowed. All patients had at least moderate MR. Additionally, patients with inadequate image quality for analysis, insufficient electrocardiogram tracings on their echocardiogram study, not in sinus rhythm, frequent ectopy, a PR interval of > 0.24 seconds, or > 20 bpm discrepancy between the heart rate on the preoperative and post-operative studies were excluded.

Demographic, clinical, and baseline echocardiographic data were extracted from electronic medical records. In terms of surgical history, it was recorded if this was the first MV intervention (labeled primary surgery) and if any additional cardiac lesions were repaired at the time of MV intervention (labeled secondary surgery). Qualitative estimates of ventricular function were also collected from the corresponding echocardiography reports and graded on a 1–4 scale for normal function to severe dysfunction, respectively. In addition, if a catheterization was performed within 3 months prior to the operation, the left ventricular end-diastolic pressure (LVEDP) was recorded.

Echocardiographic protocol

Previously acquired 2D and Doppler echocardiograms obtained according to a standardized protocol were analyzed. In addition to the LVEF, we also measured the mean dP/dt during isovolumetric contraction (mean dP/dt_ic) as previously described.¹⁰ Mean dP/dt_ic henceforth is referred to as dP/dt_ic. dP/dt_ic is calculated as the difference between the aortic diastolic blood pressure and ventricular end-diastolic pressure divided by isovolumetric contraction time. Briefly, the isovolumetric contraction time (ICT) was calculated by subtracting the time interval between a salient point on the QRS complex and the closure of the mitral valve on the LV inflow Doppler tracing, from the time interval between the same point on the QRS complex and the opening of the aortic valve on the LV outflow Doppler tracing. An average of 3 measurements was used for the calculation. Aortic diastolic pressure was obtained from an automated blood pressure monitoring system using an appropriately sized cuff during the echocardiographic study. In patients with a preoperative cardiac catheterization, the value of the LVEDP obtained during the catheterization was used for the calculation of dP/dtic. For those without pre-operative catheterizations, LVEDP was assumed to equal 10.0 mm Hg, the median of the LVEDPs available from the subset of 18 patients with a catheterization (Table 1). For the postoperative studies, the LVEDP was assumed to have fallen by 2 mm Hg from preoperative values, due to the elimination/reduction of the MR. Note that because ventricular end-diastolic pressure is usually much less than aortic diastolic pressure, errors in the estimation of ventricular end-diastolic pressure introduce relatively small errors into the calculation of dP/dtic.^11–13 A normal dP/dtic is typically ~ 1100 mm Hg/s and ventricular function that is two standard deviations below normal corresponds to a dP/dt_ic of ~ 850 mm Hg/s.¹²

We also measured the Tei index, an index of ventricular systolic and diastolic function that can be measured from the same Doppler tracings as the dP/dt_ic, as previously described.¹⁴ Tei index is calculated as the sum of isovolumetric contraction and isovolumetric relaxation times divided by the ejection time. The sum of the isovolumetric times and ejection time (component ‘a’) was calculated by measuring the time interval between the closure and subsequent reopening of the MV inflow pulse Doppler tracing. Ejection time (component ‘b’) was calculated by measuring the time interval between the opening and subsequent closure of the aortic valve on the ventricular outflow pulsed Doppler tracing. Tei index was calculated as (a-b)/b. Again, an average of 3 measurements was used for the calculation. It is important to note that higher dP/dt_ic values represent better ventricular function, and lower Tei index values represent better ventricular function. A normal Tei index is ~ 0.36 and a Tei index of ~ 0.50 is two standard deviations above (worse than) normal.¹⁴

In addition to the above indices standard echocardiographic measurements for LA monoplane volume estimation, LV end-diastolic, and LV end-systolic volumes using the ⅚*area-length method were recorded. All echocardiographic measurements were undertaken by an experienced cardiologist as well as cardiology fellows (J. R., A.G., and R.N.) blinded to the status of the patient.

Data analysis

Demographic, clinical, laboratory, and echocardiographic data were summarized using medians and either range or interquartile range (IQR) for continuous variables, and frequencies and percentages for categorical variables. The Wilcoxon signed-rank test was used to compare echocardiographic measurements and assessments of ventricular function from the preoperative to early and late postoperative periods. Spearman rank correlation coefficients were used to identify relationships between preoperative, early postoperative, and late postoperative LVEF and ventricular function variables (Tei index, EF, and dP/dt_ic). Preoperative variables were compared for patients with postoperative LVEF < 50% versus ≥ 50% using the exact Wilcoxon rank sum test. Analyses were performed using STATA version 16 (StataCorp, College Station, TX). P values ≤ .05 were deemed statistically significant.

Baseline Characteristics

A total of 61 patients were enrolled (median age 4.5 [IQR 0.14, 18.7] years), 89% mitral valve repair, 11% mitral valve replacement, 49% primary repair. The demographic and clinical characteristics are presented in Table 1. Determination of dP/dt_ic and the Tei index was possible at all 3 time points in 55 patients. The chief anatomic diagnoses for repair were reoperation of atrioventricular (AV) canal defects, MV prolapse, dysplastic MV, MV cleft, endocarditis, rheumatic heart disease, and transitional AV canal. Twenty three percent of patients had a genetic syndrome. A total of 18 patients underwent a catheterization procedure preoperatively for which the LVEDP was a median of 10.0 mmHg.

Echocardiographic Parameters

Conventional echocardiographic parameters and measurements of the Tei index and median dP/dt_ic for the cohort across the three time points are presented in Table 2. The median time interval between the preoperative study and the surgery was 6 days, between the surgery and the early postoperative study was 6 days, and between the surgery and late postoperative study was 350 days. The majority of patients had qualitatively normal systolic function preoperatively (82%), early postoperatively (67%), and late postoperatively (88%). The median end-diastolic volume was lower postoperatively with a z-score of 1.00 early postoperatively and 1.30 late postoperatively compared to a preoperative z-score of 2.95 (P value < 0.001 and 0.001 comparing early and late postoperative to preoperative volume respectively). The left atrial volume z-score was also lower postoperatively (2.75 early postoperatively and 2.85 late postoperatively) compared to a preoperative z-score of 3.70 (P value 0.001 and 0.024 respectively).

The median EF was 62% (z-score = -0.40) preoperatively (Table 2). The early postoperative EF declined to 56% (z-score = -1.40), and late postoperatively the EF improved to 61% (z-score = -0.60) (Fig. 1; P value < 0.001 and 0.017 comparing preoperative to early and late posteroperatively respectively). The average Tei index showed a similar pattern, increasing from the pre-operative to the early postoperative study, and decreasing from the early to late postoperative study without recovering to the preoperative value (Fig. 1; Table 2). The median dP/dt_ic decreased from the preoperative to the early postoperative study, and increased from the early to late postoperative study but also did not recover to the preoperative value (Fig. 1; Table 2). For the entire cohort, the median dP/dt_ic was 1393 (IQR 1029, 1775) mmHg/sec preoperatively, 1178 (IQR 886, 1946) mmHg/sec early postoperatively, and 1270 (IQR 791, 1765) mmHg/sec late postoperatively.

Correlation between Markers of Ventricular Function

The correlations between markers of ventricular function are shown in Table 3. The preoperative EF was not correlated with the preoperative dP/dt_ic (r_s = 0.02; P value = 0.88). The preoperative dP/dt_ic, however, was positively correlated with early postoperative EF (r_s = 0.28; P value = 0.028) and late postoperative EF (r_s = 0.37; P value = 0.01). Early postoperative dP/dt_ic was correlated with early postoperative EF (r_s = 0.39; P value = 0.002). The preoperative EF was not significantly correlated with early postoperative EF (r_s = 0.21, P value = 0.11), but was correlated with late postoperative EF (r_s=0.49, P value < 0.001). The preoperative Tei index was correlated with early postoperative EF (r_s = -0.28; P value = 0.032), but not late postoperative EF (r_s = -0.17; P value = 0.23).

Subset Analyses

Subset analyses comparing preoperative echocardiographic variables between patients with LV dysfunction (EF < 50%) in the early and late postoperative period versus those with normal EF (EF ≥ 50%) are shown in Table 4. A total of 13 patients had early postoperative dysfunction and 47 had normal ventricular function. A total of 3 patients had late postoperative dysfunction compared to 46 patients with normal ventricular function. Those with ventricular dysfunction in the early or late postoperative period had higher preoperative end-diastolic and end-systolic volume z-scores, and lower preoperative dP/dt_ic whereas preoperative EF were similar.In addition, those with late dysfunction had a higher preoperative Tei index. Out of 35 patients with a preoperative EF > 60%, 7 had early postoperative EF ≤ 50% and 28 had early postoperative EF > 50%. Preoperative median dP/dTic was significantly lower in the group with early postoperative decrease in EF (1017 mmHg/s [IQR 795, 1406] compared to those with normal EF (1437 mmHg/s [IQR 1181, 1971]); P value 0.011. In the patient with the largest decrease in EF (71–36%) the pre-operative mean dP/dt_ic, was 722 mmHg/s.

We observed that in pediatric patients with chronic MR undergoing MV repair or replacement most patients preoperatively have preserved ventricular systolic function, which declines in the early postoperative period and recovers in the late postoperative timeframe. This pattern was observed in all three echocardiographic indices that were studied (EF, dP/dt_ic, and Tei index), although the changes between time points did not always achieve statistical significance. In patients with a normal preoperative EF, a lower preoperative dP/dt_ic was able to distinguish patients who developed early postoperative dysfunction.

This study demonstrated a modest correlation between postoperative EF and preoperative Doppler-derived left ventricular dP/dt_ic as well as Tei index for pediatric patients undergoing surgical repair or replacement of the MV in the setting of MR. In contrast, the preoperative EF did not correlate with early postoperative EF. This suggests that in the setting of significant MR, EF may not accurately reflect the LV function and these alternative indices may be better suited in this scenario. This observation may relate to the fact that dP/dt_ic and Tei index do not rely on geometric assumptions or good acoustic windows, and are less affected by the loading changes caused by mitral regurgitation compared to EF. Mean dP/dt_ic approximates and closely correlates with the invasively measured peak dP/dt. Peak dP/dt is sensitive to changes in contractility, and only modestly affected by changes in preload.¹³ Because of the close agreement between peak dP/dt and dP/dt_ic, it is reasonable to ascribe these properties to dP/dt_ic as well. Furthermore, it can easily be calculated from measurements of the diastolic blood pressure and acquired Doppler tracings of the aortic and mitral valves.^7,10

In adults with chronic MR, the regurgitation tends to get worse over time and decreased contractility often develops despite an often normal EF.¹⁵ In those that develop an EF 50–60% and particularly EF < 50% the prognosis is guarded.⁴ Similar to the adult literature, we observed in our pediatric cohort that contractility may be reduced despite a normal EF and that those with a preserved EF preoperatively also had a preserved EF at late follow-up.¹⁵ It is not common practice to perform a catheterization in pediatric patients with this disease. Therefore, echocardiography remains standard of care for routine disease surveillance. As such, Doppler-based measures such as dP/dtic and the Tei index may have additional advantages in young children in whom obtaining accurate volumetric data can be challenging without the use of sedation. In adults undergoing mitral valve surgery for MR, echocardiographically determined dP/dt_ic as an index of ventricular function was found to be one of the best predictors of post-operative EF (ref).

Similar to published studies in adults without CHD we found that preoperative dP/dt_ic correlated modestly with early and late postoperative EF whereas preoperative EF correlated only with late postoperative EF. This may be because chronic MR causes LV dilatation from adaptive remodeling to the volume overload.⁷ Consequently, the EF preoperatively often remains in normal ranges despite significant impairment of LV contractility.^2,15 Prior studies on adults found a stronger correlation (r 0.75) between preoperative dP/dt_ic and postoperative EF, which likely reflects the overall relatively small sample of patients in our cohort and in particular those with depressed ventricular function postoperatively.

Limitations

This was a single-center, retrospective analysis of a relatively small cohort. Mitral valve anatomy, indications for surgery, and follow-up of patients who underwent interventions were not standardized. As a referral center, many patients were excluded who were lost to follow-up or who did not have ongoing care at our institution. Additionally, time intervals between the echocardiographic measurements varied significantly from individual to individual. The estimation of dP/dtic has potential sources of error including the assumption of LV end-diastolic pressure in some patients as well as use of cuff diastolic pressure as a surrogate for aortic diastolic pressure. Nonetheless, large errors in the estimation of ventricular end diastolic pressure introduce only small errors in the calculation of dP/dtic. Moreover, if, as is likely, an improvement in ventricular function is associated with a fall in LVEDP > 2 mmHg, our methodology would have, if anything, underestimated the pressure change during ICT.

In pediatric patients with chronic MR, mitral valve intervention is associated with an initial decline in function, but long-term recovery of ventricular function. In these patients, Doppler-derived indices of ventricular performance in the form of dP/dtic and Tei index may better identify patients at risk of postoperative LV dysfunction compared to EF. Further investigation is warranted to ascertain whether these indicators surpass EF in predicting clinical outcomes, such as functional status.

Author Contribution

S.E., J.R., S.B., and R.N. conceptualized the design.F.S. and K.G. performed the statistical analysis and created the figure.A.G., S.J.G, J.R. and N.T. wrote the main manuscript text and prepared the tables.All authors reviewed the manuscript

Conflict of interest: The authors report no conflict of interest with this report.

Ethical Approval: This article has achieved Institutional Review Board approval

Grants Contracts or other forms of financial support: SB is supported by the Fred Lovejoy Housestaff Research and Education Fund. AG is supported the Matthews Heart of Hope’s Grant and NIH T32 Grant.

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Table 1: Preoperative Clinical Characteristics of Patient Cohort

Age at surgery (years), N=61	4.5 (51d, 18.7)
Primary cardiac surgery Mitral valvuloplasty Mitral valve replacement	54 (89%) 7 (11%)
Any secondary surgery	17 (28%)
Primary repair	30 (49%)
Primary cardiac diagnosis Reoperation AV canal MV prolapse Dysplastic MV MV cleft Recurrent MR Endocarditis Severe MR Moderate MR s/p MV repair Mixed MV disease Rheumatic heart disease Severe MR with mitral cleft, trisomy 21 Transitional AV canal	13 (21%) 12 (20%) 10 (16%) 10 (16%) 5 (8%) 4 (7%) 2 (3%) 1 (2%) 1 (2%) 1 (2%) 1 (2%) 1 (2%)
Any genetic syndrome	14 (23%)
If syndrome, genetic diagnosis Marfan Noonan Trisomy 21 Other	4 1 7 2
Any catheterization	18 (30%)
LVEDP, if cath performed (n=18)	10.0 (8, 18)

Values shown are number (percent) or median (range). AV, atrioventricular; MV, mitral valve; LV, left ventricle; LVEDP, left ventricular end diastolic pressure.

Table 2

Echocardiographic Indices, by Time Point
	Preoperative (n = 61)	Early Postoperative (n = 61)	Late Postoperative (n = 55)	Pre vs Early P Value	Pre vs Late P Value
Time before/after surgery (d)	6 [2, 36]	6 [4, 7]	350 [233, 434]	--	--
Qualitative function (n = 57,61,52) 1 Normal 1.5 Borderline 2 Mildly depressed 2.5 Mild to moderate 3 Moderately depressed 3.5 Moderate to severe 4 Severely depressed	47 (82%) 6 (11%) 3 (5%) 0 (0%) 1 (2%) 0 (0%) 0 (0%)	41 (67%) 8 (13%) 8 (13%) 2 (3%) 1 (2%) 0 (0%) 1 (2%)	46 (88%) 1 (2%) 2 (4%) 0 (0%) 2 (4%) 1 (2%) 0 (0%)	0.006	0.83
Heart rate (n = 60,60,53)	98 [80, 113]	102 [87, 115]	93 [78, 110]	0.18	0.011
EDV (n = 61,60,49)	69.5 [32.7, 107.6]	47.7 [26.5, 73.2]	64.0 [35.3, 90.8]	< 0.001	0.51
EDV z-score (n = 61,60,49)	2.95 [0.96, 4.60]	1.00 [-0.21, 2.48]	1.30 [0.15, 2.34]	< 0.001	0.001
ESV (n = 61,60,48)	25.3 [11.5, 38.6]	18.6 [10.3, 34.4]	23.3 [13.0, 39.7]	0.043	0.37
ESV z-score (n = 61,60,48)	2.80 [1.10, 3.69]	1.66 [0.54, 3.28]	1.60 [0.77, 2.90]	0.007	0.015
Ejection fraction (n = 61,60,49)	61.7 [58.0, 67.8]	56.4 [50.0, 62.0]	61.0 [57.0, 64.3]	< 0.001	0.017
EF z-score (n = 61,60,48)	-0.40 [-1.13, 0.81]	-1.40 [-2.41, -0.34]	-0.60 [-1.43, 0.21]	< 0.001	0.009
LA volume (n = 29,23,22)	53.2 [23.8, 80.1]	29.9 [16.6, 48.7]	44.2 [32.1, 49.0]	0.003	0.17
LA volume z-score (n = 28,23,22)	3.70 [2.16, 5.60]	2.75 [2.15, 4.30]	2.85 [1.08, 4.78]	0.001	0.024
Mean dP/dt_ic (n = 61,61,50)	1393 [1029, 1775]	1178 [886, 1946]	1270 [791, 1765]	0.21	0.64
Tei index (n = 61,61,50)	0.30 [0.23, 40]	0.39 [0.33, 0.50]	0.33 [0.26, 0.43]	0.002	0.90

Indices are compared using Wilcoxon signed-rank test. Values shown are number (percent), median [25th, 75th percentile], or mean ± standard deviation. EDV, end diastolic volume; ESV, end systolic volume; LA, left atrium; EF, ejection fraction.

Table 3

*Correlation between Markers of Ventricular Function*
	Preop EF	P value	Early Postop EF	P value	Late Postop EF	P value
Preoperative Mean dP/dt_ic	r_s = 0.02	0.88	r_s = 0.28	0.028	r_s = 0.37	0.010
Preoperative EF	--	--	r_s = 0.21	0.11	r_s = 0.49	< 0.001
Preoperative Tei Index	r_s = -0.12	0.35	r_s = -0.28	0.032	r_s = -0.17	0.23
Early Postop dP/dt_ic	r_s = 0.10	0.42	r_s = 0.39	0.002	r_s = 0.20	0.17
Preoperative LA Volume	r_s = 0.17	0.39	r_s = -0.43	0.021	r_s = -0.29	0.19

Spearman correlation coefficients

Table 4

*Comparison of Preoperative Variables by Early and Late Postoperative Ejection Fraction*
	Early Postop EF < 50% (n = 13)	Early Postop EF ≥ 50% (n = 47)	P Value	Late Postop EF < 50% (n = 3)	Late Postop EF ≥ 50% (n = 46)	P Value
EDV	85.7 [45.6, 122.2]	61.1 [27.1, 104.3]	0.23	155.7 [72.7, 173.3]	63.5 [32.7, 107.1]	0.076
EDV z-score	4.20 [3.44, 6.68]	2.34 [0.60, 4.47]	0.031	5.18 [3.90, 5.39]	2.84 [0.96, 4.51]	0.10
ESV	29.6 [23.9, 47.6]	19.0 [10.5, 35.5]	0.11	61.1 [48.7, 108.8]	23.7 [10.8, 35.4]	0.012
ESV z-score	5.03 [3.46, 5.80]	2.02 [0.80, 3.26]	0.001	5.80 [3.69, 6.08]	2.32 [0.80, 3.52]	0.019
EF	62 [51, 67]	62 [58, 68]	0.29	37 [33, 61]	62 [59, 68]	0.041
EF z-score	-0.40 [-2.34, 0.75]	-0.34 [-1.10, 0.87]	0.25	-6.05 [-6.20, -0.58]	-0.24 [-0.90, 0.90]	0.043
Mean dP/dt_ic	1017 [795, 1406]	1437 [1181, 1971]	0.011	881 [536, 1141]	1420 [1029, 1779]	0.048
Tei index	0.40 [0.28, 0.56]	0.29 [0.22, 0.38]	0.048	0.56 [0.56, 0.75]	0.30 [0.23, 0.39]	0.015

Values shown are median [25th, 75th percentile] or mean ± standard deviation. EDV: end diastolic volume; ESV: end systolic volume; LA: left atrium; EF: ejection fraction.

No competing interests reported.

Preoperative Echocardiographically Derived Mean dP/dTic Predicts Early Post-operative Dysfunction in Children Undergoing Mitral Valve Surgery

Status:

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Abstract

Background

Methods

Results

Conclusions

Figures

Introduction

Methods

Study Population

Echocardiographic protocol

Data analysis

Results

Baseline Characteristics

Echocardiographic Parameters

Correlation between Markers of Ventricular Function

Subset Analyses

Discussion

Conclusions

Declarations

Author Contribution

References

Tables

Additional Declarations

Status:

Journal Publication

Version 1