Fetal Cardiology

Fetal growth of left-sided structures and postnatal surgical outcomes in the “borderline” left heart varies by cardiac phenotype.

Fetal growth of left-sided structures and postnatal surgical outcomes in the "borderline" left heart varies by cardiac phenotype. Venardos A, Colquitt J, Morris SA. Ultrasound Obstet Gynecol. 2021 May 16. doi: 10.1002/uog.23689. PMID: 33998097   Take home points: The authors in this study demonstrates that the growth of left sided cardiac structures in utero varies by the phenotype observed on fetal echocardiogram. Those with severe left heart hypoplasia but with an apex-forming left ventricle and without aortic stenosis (“long and skinny”) grow at a faster rate than those with severe aortic stenosis. This work informs fetal cardiologists to counsel parents of fetuses with left heart hypoplasia and an apex-forming left ventricle that the left-sided structures are likely to grow and there is high likelihood of biventricular repair. In contrast, with severe fetal aortic stenosis there is minimal growth of left-sided structures over gestation. Commentary from Dr. Manoj Gupta (New York City, NY, USA), chief section editor of Pediatric & Fetal Cardiology Journal Watch:   Introduction Two “borderline” left heart phenotypes are encountered in the fetus: the “short, fat” globular left ventricle (LV) with systolic dysfunction, and the “long, skinny” LV in which the LV is apex-forming and systolic function is typically preserved. The “short, fat” phenotype is classically seen with severe aortic stenosis (AS) that has progressed past a stage of LV dilation. In the “long, skinny” phenotype, the LV is apex forming and hypoplastic in short axis dimension, has laminar flow across hypoplastic mitral and aortic valves, and arch hypoplasia is present. This phenotype is often termed “left heart hypoplasia” (LHH), “hypoplastic left heart complex”, or “Shone complex variant”.   Methods Inclusion criteria for the severe AS group were: aortic annulus Z score <-2.0, severe AS defined as either minimal antegrade flow across the aortic valve (regardless of flow velocity) or evidence of valve narrowing with peak velocity >3 meters/second, patent aortic valve on first study, qualitatively depressed LV systolic function (to any degree), retrograde systolic flow in the arch, and endocardial fibroelastosis present at any point in gestation.   Inclusion criteria for the LHH group were: aortic annulus Z-score <-2.0, apex forming but narrow LV, qualitatively normal LV function, absence of endocardial fibroelastosis, and retrograde systolic flow in the aortic arch in the absence of atrial septal aneurysm. Retrograde systolic flow in the arch is very important in this group as this is indicative of the more severe form of LHH.   For each echocardiogram, two dimensional measurements of the aortic valve annulus, mitral valve annulus, LV short axis dimension, LV long axis length, distal transverse arch, and aortic isthmus were collected.   Results At the first fetal echocardiogram, fetuses with LHH had a later gestational age, larger aortic annulus diameter, and larger LV long axis dimension. There was no significant difference in initial arch measurements or LVED short axis dimension. The mean rate of aortic annulus growth was faster in the LHH group compared to the AS group. In the AS cohort, 3 (15%) died prior to intervention, 15 (75%) underwent single ventricle palliation, and 2 (10%) underwent biventricular repair. In the LHH cohort, 1 (3.1%) died prior to intervention, 3 (9.4%) underwent single ventricle palliation, and 28 (87.5%) underwent biventricular repairs (n=22) or no surgeries (n=6)     *Arch advancement is a repair via sternotomy for long segment arch hypoplasia using entirely native tissue. **One LHH patient who had initial biventricular repair ultimately required single ventricle palliation   Discussion This study demonstrates that the aortic annulus and other left sided structures (mitral valve and left ventricle) grow at a faster rate in fetuses with severe LHH than in fetuses with severe AS. A majority of infants in the AS group underwent single ventricle palliation, while a majority of infants in the LHH group had a biventricular circulation.   Overall mortality was higher in AS (11/20, 55%) compared to LHH (3/32, 9%). While the mortality in the AS group is quite high, this includes patients whose families chose comfort care.   Conclusions The aortic valve, mitral valve, and LV do continue to grow throughout gestation at a faster rate in the LHH group than in the AS group. Still, the majority of those with LHH underwent biventricular repair while most of those with AS underwent single ventricle repair. In current practice, fetuses with severe AS and those with severe LHH may both counseled that the left-sided structures may not grow well, and that a single ventricle palliation is likely postnatally. However, we have shown that counseling should be targeted to the fetal cardiac phenotype.   

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Impact of Socioeconomic Status, Race and Ethnicity, and Geography on Prenatal Detection of Hypoplastic Left Heart Syndrome and Transposition of the Great Arteries

Impact of Socioeconomic Status, Race and Ethnicity, and Geography on Prenatal Detection of Hypoplastic Left Heart Syndrome and Transposition of the Great Arteries. Krishnan A, Jacobs MB, Morris SA, Peyvandi S, Bhat AH, Chelliah A, Chiu JS, Cuneo BF, Freire G, Hornberger LK, Howley L, Husain N, Ikemba C, Kavanaugh-McHugh A, Kutty S, Lee C, Lopez KN, McBrien A, Michelfelder EC, Pinto NM, Schwartz R, Stern KWD, Taylor C, Thakur V, Tworetzky W, Wittlieb-Weber C, Woldu K, Donofrio MT; Fetal Heart Society. Circulation. 2021 May 25;143(21):2049-2060. doi: 10.1161/CIRCULATIONAHA.120.053062. Epub 2021 May 17.PMID: 33993718   Take Home Points: Lower socioeconomic quartile (SEQ), Hispanic ethnicity, and rural residence are associated with decreased prenatal detection (PND) for d-TGA Lower SEQ is associated with decreased PND for HLHS Future directives, including advanced geo-mapping to identify at risk areas, improving outreach and education of OBs to include outflow tract views, as well as use of telehealth when distance to a surgical center, may help improve PND Commentary from Dr. Jared Hershenson (Greater Washington DC), section editor of Pediatric Cardiology Journal Watch: Prenatal detection of significant CHD such as in HLHS or d-TGA has been shown to improve morbidity and mortality. It can improve delivery planning and allow for proper coordination of care, especially if intervention is necessary soon after delivery. A focus in the fetal cardiology world is to continue to improve PND, and understanding the barriers to PND is important to create an effective strategy for prevention and improving outcomes. The purpose of this study was to determine the effect of social determinants of health on PND of CHD. This was a large, multicenter retrospective cohort study that included 21 North American centers (19 USA and 2 Canada). The study population included prenatally and postnatally diagnosed fetuses with HLHS or d-TGA. These 2 diagnoses represent the most common critical newborn CHD. The primary independent variables included SEQ, neighborhood poverty level > 20%, neighborhood race/ethnicity, rural residence, at risk geographic location, driving distance to surgical center, maternal insurance, and maternal race/ethnicity. The paper explains how SEQ and neighborhood scores were determined. Of note, insurance status was not examined for the Canadian cohort and patients without insurance were not examined in the US cohort.   1862 patients were included; 1171 with HLHS (91.8% prenatally diagnosed) and 691 (58% prenatally diagnosed) with d-TGA. See table 1. On unadjusted analysis, in the US, only lower SEQ was associated with lower PND in the d-TGA group. Adjusted analyses were performed to adjust for maternal age and accounting for hospital clustering. This showed that PND was 6% less likely among the lowest SEQ for HLHS and up to 22% in the d-TGA group with the lowest SEQ. In the US, PND was less common for Hispanic mothers and those from a rural location. In the Canadian cohort, further distance was associated with a lack of PND in the HLHS group but not the d-TGA group. See table 3. Lower SEQ was also associated with later gestational age at PND in both US/Canada, and public insurance, rural residence and longer distance to surgical center were associated with later GA at PND in the US.   In the discussion, the authors note that public insurance was not associated with decreased PND, a finding that had been seen in some previous studies. They also speculate that the difference in PND for HLHS vs d-TGA, while better than previous studies, may be due to the fact that HLHS can be more readily identified on the 4 chamber view, while d-TGA requires outflow tract views which are not always obtained on the OB sonogram. Also, given the overall high rate of detection for HLHS, access to prenatal care may not necessarily be the barrier for the small group of HLHS patients that were not detected. Another interesting finding was that universal health care did not necessarily improve PND, as overall rates were similar between the US and Canada. However, only 2 sites in Canada were studied. They recommend future directives, including advanced geo-mapping to identify at risk areas, improving outreach and education of OBs to include outflow tract views, as well as use of telehealth when distance to a surgical center is an issue.      

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