The PERInatal MYocardial Remodeling (PERIMYR) cohort study protocol: A prospective study of cardiac remodeling and "recovery" in pregnancy as a model to understand the impact of comorbidities in cardiac remodeling and reverse remodeling

INTRODUCTION

Heart failure (HF) is among the leading causes of morbidity and mortality worldwide. Several conditions trigger left ventricular chronic pressure or volume overload, hypertrophy, systolic and diastolic dysfunction, leading to cardiac remodeling and a rapid progression toward HF. Therapeutic interventions elicit reverse remodeling (RR), a highly variable myocardial response that ranges from none to total ventricular structural/functional recovery. However, HF patients present several comorbidities and medications that mask a comprehensive molecular knowledge of RR and hinder the identification of potential biomarkers of its progression or prognosis. Therefore, instead of using this heterogeneous population or even animal models to understand myocardial remodeling, we propose studying pregnancy-induced cardiovascular remodeling and postpartum-induced RR.

OBJECTIVES

To assess cardiovascular functional and structural adaptations during pregnancy and in postpartum, characterizing the associated molecular changes; as well as to explore the impact of hypertension, obesity and diabetes on these processes.

METHODS

We will perform echocardiography and assess endothelial function and arterial stiffness (EndoPAT® and pulse wave velocity, respectively) and assess potential markers of remodeling and RR using plasma and urine samples from pregnant women. To translate to a HF context, we will determine the impact of risk factors (hypertension, obesity and diabetes) by studying subgroups of pregnant women with these comorbidities.

RESULTS

Not applicable Conclusion: We are convinced that understanding the impact of these comorbidities in such a homogeneous population, such as pregnant women, provides a valuable model to unveil the most relevant pathologic and often masked signaling pathways underlying cardiac remodeling and incomplete RR in a heterogeneous population, such as HF patients. Moreover, we expect to identify potential novel biomarkers of RR progression/prognosis more easily.

Cardiac remodelling and reverse remodelling in pregnant women: what can be expected?

Introduction

Hemodynamic overload during pregnancy induces cardiac remodelling which is characterized by left ventricle (LV) eccentric hypertrophy and left-atrium enlargement.After delivery,the woman's heart undergoes reverse remodelling and myocardial performance normalize to their pre-gravid structure and function.

Aim

To characterize cardiac remodelling and reverse remodelling during pregnancy and postpartum, respectively, as well as to investigate the impact of cardiovascular (CV) risk factors in these processes.

Methods

This prospective cohort study included volunteer pregnant women recruited in a tertiary centre between 2019 and 2020.Women were evaluated by transthoracic echocardiography and pulse wave velocity at the 1st trimester [1T, baseline], 3rd trimester [3T, peak of CV remodelling] of pregnancy as well as at the 1st month and 6th month after delivery (reverse remodelling). Mann-whitney,wilcoxon and Ffriedman test were used as appropriate to between and within groups comparisons. Bonferroni correction was applied. Spearman correlation was performed to determine the relationship between pulse wave velocity (PWV) and echocardiographic variables.

Results

We included 32 pregnant women with a median age of 34 [26; 41] years, 50% being hypertensive and/or obese. The pregnant women tended to develop eccentric hypertrophy pattern during pregnancy, characterized by significant increase of cardiac mass index (CMi) from 1T to 3T (table 1, p=0.006) and slight modification of relative wall thickness (RWT, table 1, p=0.339). During postpartum, hypertrophy regression became significant only at 6 months after delivery (CMi: table 1, p<0.001; RWT: table 1, p<0.001). In contrast, a fastest recovery of indexed left atrial (3T to 1 month postpartum:table 1,p=0.033) and ventricular volumes (table 1, p<0.001) was observed after delivery, despite its slight enlargement during pregnancy (atrium-table 1, p=0.55; LV-table 1, p=0.084). RWT correlated positively with PWV at 3T (r=0.447, p=0.012). Compared to the healthy pregnant women,CV risk factors group showed higher RWT in all time points of follow-up period,without any differences in CMi and cardiac volumes indexed. Filling pressures increased during gestation (table 1, p=0.002),normalizing as soon as 1 month after delivery (table 1, p=0.001) and maintained at the 6th month (table 1, p<0.001). Pregnant women with CV risk factors revealed a significant higher value of E/e' in comparison with the healthy group, but only at the 6th month of postpartum (5.6 [5.2; 8.2] vs 5.4 [4.4; 7.7], p=0.036).

Conclusion

In our cohort, complete reverse remodelling occurs as soon as one month after delivery, with the exception of hypertrophy.The positive correlation between relative wall thickness and pulse wave velocity highlighted arterial-ventricular coupling relevance for the cardiac remodelling process during pregnancy. Pregnant women with CV risk factors showed higher relative wall thickness when compared with healthy women at all time points of the follow-up.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Universidade do Porto/FMUP and FSE-Fundo Social Europeu; FCT - Foundation for Science and Technology

Impact of cardiovascular risk factors in vascular remodelling of pregnant women

Introduction

Pregnancy is a physiological condition of hemodynamic overload, characterized by a progressive reduction of peripheral vascular resistance, which normalizes postpartum.

Purpose

To characterize arterial stiffness and endothelial function during pregnancy and postpartum and to investigate the impact of cardiovascular (CV) risk factors. The secondary aim was to explore the potential association between pulse wave velocity (PWV) and risk for preeclampsia.

Methods

Prospective cohort study including volunteer pregnant women (healthy, obese and/or hypertensive) recruited in a tertiary centre between 2019 and 2020, at their 1st or 3rd trimester of pregnancy. Women were evaluated at the first trimester [10–15 weeks, baseline], third trimester [30–35 weeks, peak of CV remodelling] of pregnancy as well as at the 1st month and 6th month after delivery (CV reverse remodelling stages). The evaluation included clinical characterization through questionnaires as well as arterial stiffness and endothelial assessment by PWV and EndoPAT, respectively. Kruskal-Wallis H test and Friedman test were used as appropriate to between and within groups comparisons. Bonferroni correction was applied. Spearman correlation was performed to determine the relationship between PWV and risk for preeclampsia.

Results

We included 34 pregnant women with a median age of 34 [26; 41]years, 50% being hypertensive and/or obese. Arterial stiffness decreased significantly from the 1st to the 3rd trimester (6.3 [5.3 to 7.8] cm/s vs 5.6 [4.9 to 7.3] cm/s, p<0.001), normalizing only at the 6th months (5.6 [4.9 to 7.3] cm/s vs 6.3 [5.5 to 8.3] cm/s, p=0.001). A significant deterioration of endothelial function became evident from 1st to 3rd trimester (logarithm of reactive hyperemia index [lnRHI]: 0.74 [0.05 to 1.20] vs 0.45 [0.22 to 0.79], p=0.020). However, its slight amelioration begun only 6 months after delivery (3rd trimester: lnRHI 0.45 [0.22 to 0.79] vs 6 months at postpartum: lnRHI 0.53 [0.10 to 1.01], p>0.99). Compared to the healthy pregnant women, the CV risk factors group showed a higher pulse wave velocity only at the peak of CV remodelling (5.6 [5.3 to 7.3] cm/s vs 5.6 [4.9 to 7.2] cm/s, p=0.016), without any other differences in other parameters of time points evaluated. Pulse wave velocity at the first trimester revealed a positive association with risk for preeclampsia (r=0.485, p=0.026).

Conclusion

Our cohort presented a significant decrease in vascular resistance during pregnancy and normalization at the 6th month after delivery. Pregnant women with cardiovascular risk factors showed an increased arterial stiffness in the 3rd trimester compared to healthy pregnant women. Pulse wave velocity correlated positively with the risk for preeclampsia.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Universidade do Porto/FMUP and FSE-Fundo Social Europeu; FCT - Foundation for Science and Technology

Colostrum yield and litter performance in multiparous sows subjected to farrowing induction

The consumption of colostrum at a low level can compromise the survival and growth of piglets. Therefore, this study aimed to evaluate the effect of farrowing induction on colostrum yield, IgG concentration and the survival and performance of piglets until the weaning. Sows of parity 3 to 7 were assigned into two groups: Control (n = 48), sows with spontaneous farrowing; and induction (n = 48), sows induced to farrow on day 114 of gestation with a PGF₂ analogue. Colostrum and blood samples were collected from the sows, at farrowing and 24 hr later. Blood samples from the piglets were collected at 24 hr after birth. The performance of the piglets was evaluated in a subsample of 28 litters from each group. All piglets were weighed at 7, 14 and 20 days of age. The farrowing length, the number of piglets born alive, stillborn piglets, weight at birth, litter weight at birth and colostrum yield were not significantly affected (p > .05) by farrowing induction. There was no difference between the groups (p > .05) in the percentage of sows with obstetric interventions. Serum IgG concentration, in both sows and piglets, and colostrum IgG concentration were similar between the groups (p > .05). Furthermore, survival rate, piglet weight and litter weight at 7, 14 and 20 days of age were also similar between the groups (p > .05). Therefore, it can be concluded that the farrowing induction performed on day 114 of gestation does not affect the colostrum yield, the IgG concentration in colostrum and serum of piglets, and the litter performance until the weaning.

Concordance for bilateral congenital diaphragmatic hernia in a monozygotic dichorionic twin pair - first clinical report

The authors present a clinical case of concordance for bilateral congenital diaphragmatic hernia in a monozygotic twin pair diagnosed in the early second trimester.

Life cycle assessment of wastewater treatment options for small and decentralized communities

Sustainability has strong implications on the practice of engineering. Life cycle assessment (LCA) is an appropriate methodology for assessing the sustainability of a wastewater treatment plant design. The present study used a LCA approach for comparing alternative wastewater treatment processes for small and decentralised rural communities. The assessment was focused on two energy-saving systems (constructed wetland and slow rate infiltration) and a conventional one (activated sludge process). The low environmental impact of the energy-saving wastewater treatment plants was demonstrated, the most relevant being the global warming indicator. Options for reduction of life cycle impacts were assessed including materials used in construction and operational lifetime of the systems. A 10% extension of operation lifetime of constructed wetland and slow rate infiltration systems led to a 1% decrease in CO2 emissions, in both systems. The decrease in the abiotic depletion was 5 and 7%, respectively. Also, replacing steel with HDPE in the activated sludge tank resulted in a 1% reduction in CO2 emission and 1% in the abiotic depletion indicator. In the case of the Imhoff tank a 1% reduction in CO2 emissions and 5% in the abiotic depletion indicator were observed when concrete was replaced by HDPE.

Tobacco smoking among Portuguese high-school students

The aim of this study was to evaluate the prevalence, behavioural patterns, and determinants of smoking among a large sample of high-school students from Porto, the second largest city in Portugal, information on sociodemographic characteristics and personal history of tobacco, alcohol, coffee, and illicit drug use was obtained from 2974 students, aged 12-19 years (48.7% female, 51.3% male), using an anonymous self-administered questionnaire. Crude and adjusted odds ratios (OR) were calculated by logistic regression analysis to estimate the association between smoking and the characteristics evaluated. Overall, 35.8% students had never smoked, 39.4% had tried it ("experimental" smokers) but were not smokers, 3.3% were former smokers, 6.6% occasional smokers, and 14.9% regular smokers. The mean age for starting smoking was 13.4 +/- 2.1 years for males and 13.4 +/- 1.6 years for females. The prevalence of current smoking was higher among males than females, but the difference was not significant. Male students were significantly more likely to smoke more cigarettes per day than were females. The prevalence of smoking was significantly associated with the following variables: being aged > 12 years; having parents who had attended school for < 4 years; having a mother (OR = 1.88), siblings (OR = 1.96) or friends (OR = 1.75) who smoked; low academic performance (OR = 1.74 for one or two failures and OR = 2.27 for more than two failures at school); and consumption of coffee (OR = 2.90), alcohol (OR = 3.53), or illicit drugs (OR = 6.69). The prevalence of smoking among adolescents increased with age. There is therefore a need for school-based tobacco prevention programmes which also deal with family influences on smoking.

[Mother-child transmission of immunoglobulins G]

The placental transfer of immunoglobulins is made by active transport and only IgG class of immunoglobulins is transferred. In a full-term gestation IgG concentration is usually higher in the cord serum than in the mother serum. It has been shown that the ratio of cord/maternal IgG is higher when maternal IgG values are low. A series of 44 mother-child pairs from the north of Portugal were studied. Quantitative determination of IgG in all sera was made by single radial immunodiffusion and results were expressed in milligrams/deciliter (mg/dl). In the first 48 hours after delivery, mothers were interviewed and clinical, social and demographic data were collected. In 35 pairs, cord IgG exceeded the corresponding maternal concentration. The ratio of cord/maternal IgG ranged from 0.75 to 2.86 (mean 1.27). From all studied variables only maternal IgG concentration and age were correlated with that ratio. Transplacental concentration (ratio of cord/maternal IgG) was higher for lower levels of maternal IgG. Significant contribution of maternal age did not stand when a woman with extreme values of IgG and age was withdrawn from the analysis. Values found for this series of Portuguese mother-child pairs were similar to those found for other caucasian populations and are in agreement with current proposed models for placental transfer of IgG.

[Nitric oxide-dependent endogenous and exogenous vasodilators. The mechanism of action of nitrates]

The concept of endothelium-dependent vasodilation was developed after the discovery in 1980 of the endothelium-derived relaxing factor (EDRF) by Furchtgott and Zawadzki. In 1987 Furchgott and Ignarro identified the EDRF with nitric oxide. In the same year Moncada and coworkers demonstrated that the liberation of nitric oxide by endothelial cells was responsible by the biologic activity of EDRF. Nitric oxide is the endogenous mediator responsible by the endothelium-dependent vasodilation and can be considered the endogenous nitrovasodilator. But nitric oxide has a more complex spectrum of action, because it participates in the regulation of platelet activity and preservation of the normal structure of the vessel wall. Nitric oxide is also the terminal product of the biotransformation of therapeutic nitrates responsible by guanylate cyclase activation. Nitrates can be classified as endothelium non dependent vasodilators because some of them release spontaneously nitric oxide from their metabolites, and others are biotransformed to nitric oxide in vascular smooth muscle cells.

Insights into the role of thromboxane A2 and serotonin in the pathogenesis of unstable angina

New research about platelet and endothelial functions is allowing us to better understand the pathogenesis of myocardial ischemic episodes in patients with unstable angina, creating new perspectives for the rational utilization of therapies. In patients with unstable angina, the episodes of symptomatic and silent ischemia are caused by repeated reductions of coronary blood flow. They are the result of the mechanical effect of the growing thrombus, which causes intermittent episodes of partial obstruction of the arterial lumen, in association with vasoconstriction at the stenotic site and dependent coronary arterial bed, produced by the cyclic release of platelet derived vasoactive products, namely thromboxane A2 and serotonin. Several studies, many of them in animal models of thrombosis, suggest that serotonin and thromboxane A2 are mediators of platelet aggregation, adynamic obstruction and coronary artery thrombosis. Because they cause coronary cyclic flow reductions, they are implicated in the pathogenesis of myocardial ischemic episodes during unstable angina. Drugs that interfere with the arachidonate pathway, and the 5-HT2-receptor antagonists, have been proven to decrease or abolish coronary cyclic flow variations in animal models and man. However, further studies should be done to test the hypothesis that the association of a 5-HT2-receptor antagonist with aspirin may contribute to decrease myocardial ischemia and prevent coronary occlusion in patients with unstable angina. Continuous Holter monitoring during the first week after admission in the hospital should be a good method to evaluate the eventual efficacy of this new class of drugs in abolishing or decreasing the frequency, intensity and duration of myocardial ischemic episodes in patients with unstable angina. The central role of serotonin in the pathogenesis of thrombotic events, and the presumed preventive effect of ketanserin, were the bases of a national multicenter pilot controlled study designed to evaluate the safety and efficacy of ketanserin plus aspirin in the secondary prevention of patients with unstable angina and non-Q wave myocardial infarction (KATUA Trial).

[Comparison of Holter electrocardiography and thallium 201 scintigraphy in the detection of myocardial ischemia]

OBJECTIVE OF THE STUDY

To compare ischemic changes (I) detected by Holter ECG (H ECG) to the myocardial perfusion defects found in 201 TI myocardial perfusion scintigraphy.

DESIGN

201 TI exercise test was made during the performance of a 24 hours H ECG. The validation of ST segment changes detected by H ECG during the exercise test was made on basis of reversible myocardial perfusion defects (RPD) detected on 201 TL and a relation between ST segment changes detected during the remaining 24 hours recording period and 201 TI (TI) RPD was established.

SETTING

The patients (pt) included in the study have come from Cardiology and Heart Surgery Clinics of a Central teaching hospital.

MATERIAL AND METHODS

20 pt with a high coronary artery disease prevalence have been submitted to a two lead (V5 and aVF) 24 hour H ECG during which they have performed a symptom limited bicycle exercise test followed by an injection of 201 TI with acquisition 5 minutes later. Ischemic episodes detected on H ECG were quantified and their relation with heart rate and symptoms was established. As far as 201 TI studies are concerned the fixed and reversible perfusion defects as well as their location were evaluated.

RESULTS

1. H ECG: 6 pt (30%) presented ST changes on H ECG during the exercise test and a total of 9 pt (45%) had ST changes during exercise and during the remaining period of H ECG. 2. TI: 19 pt presented perfusion defects images (fixed in 7, reversible in 14, both kinds of defects in 7). 3. H ECG validation: H ECG during exercise presented I in 6 out of 14 pt with RPD on TI (sensitivity = 43%). Six of these 8 pt, with negative H and positive TI, had a chronic myocardial infarction. All the 6 pt with negative TI had negative H ECG (specificity = 100%). 4. H ECG TI comparison: 7 (50%) of the 14 pt with RPD had ST changes on 24 hrs H ECG. Seven of 11 pt with negative H ECG had RPD in TI. Two pt with negative TI had positive H ECG. These 2 pt had during H ECG a higher heart rate (HR) than the HR recorded during the exercise test.

CONCLUSIONS

1. In pt with known CAD, TI has a high sensitivity and specificity to show perfusion defects. 2. Considering TI as gold standard, H ECG showed to be a useful method to detect I in the studied population (sens. = 43%; spec. = 100%). 3. H ECG revealed to be an important diagnostic tool in detecting additional I episodes beyond the ones recorded during TI exercise test.