Research Article
Volume 1 Issue 3 - 2015
Maternal Total Vascular Resistance: A New Parameter to Identify Hypertensive Pregnancy Complications
Lo Presti D1*, Gagliardi G1, Tiralongo GM1, Pisani I1, Scala RL1, Larciprete G2, Vasapollo B2 and Valensise H1
1Department of Obstetrics and Gynaecology, Tor Vergata University, Italy
2Fatebenefratelli Association for Research, Fatebenefratelli Hospital, Italy
Corresponding Author: Larciprete G, Fatebenefratelli Association for Research, Fatebenefratelli Hospital, Isola Tiberina, Rome, Italy.
Received: March 09, 2015; Published: May 02, 2015
Citation: Lo Presti D., et al. “Maternal Total Vascular Resistance: A New Parameter to Identify Hypertensive Pregnancy Complications”. EC Gynaecology 1.3 (2015): 85-91.
Abstract
Introduction: Maternal cardiovascular system adapts to pregnancy thanks to complex physiological mechanisms that involve cardiac output and total vascular resistance. Abnormalities of this adaptive mechanisms are connected with hypertensive disorders.
Materials and methods: We enrolled 140 healthy normotensive women during the first trimester of pregnancy obtaining all measurements with the USCOM system, a non invasive method. All patients were subsequently evaluated at 16 and 22-23 weeks of gestation and were followed until the end of pregnancy to check for fetal-neonatal and maternal outcomes.
Results: Patients were retrospectively divided in two groups: Group A (n = 37): patients with TVR values persistently elevated at 22 weeks of gestation (> 1200 dyne/sec/cm-5) and Group B (n = 103): patients with a reduction of TVR values at 22 weeks of gestation (< 1200 dyne/sec/cm-5).
Among the group A, 7 patients developed gestational hypertension, 3 patients developed preeclampsia and 5 pregnancies were complicated by intrauterine growth restriction. In the Group B there is an increase in Stroke Volume and Cardiac Output; the last one result could be a compensation response ensuring a proper peripheral vascular filling.
Discussion: The introduction of USCOM has provided non invasive means for the evaluation of maternal cardiovascular adaptation. Our data showed that into 37 patients group (26.5% of the total) with persistently elevated TVR values at 22-23 weeks, 15 women (10% of the total) experienced hypertensive complications. According to our data, a maternal hemodynamic condition characterized by persistently elevated TVR values in the second trimester of pregnancy probably represents a risk factor for a poor fetal-maternal outcome representing a high-risk group of pregnant women that need to be strictly monitored.
Conclusions: TVR might help to identify pregnant women at high risk of developing hypertensive complications.
Keywords: Total Vascular Resistance; pregnancy induced hypertension; preeclampsia; USCOM; placental maladaptation
Introduction
In recent years maternal cardiac function was studied in normal and complicated pregnancy obtaining important information on systolic and diastolic function and on morphological parameters of the left ventricle [1].
During pregnancy maternal hemodynamics undergoes important physiological adaptations to ensure an adequate uteroplacental perfusion and to promote normal fetal development. In physiological pregnancies because of the remodelling of the spiral artery there is a reduction in uteroplacental resistance index associated with a decrease of the Total Vascular Resistance (TVR) which represents the steady component of the afterload and includes the uteroplacental circulation with a contribution of 20% to 26% to the total reduction of systemic vascular resistance in the second trimester [2].
Associated with the decline in Total Vascular Resistance (TVR) there is an increase in Cardiac Output (CO) and Stroke Volume (SV). These changes take place during early phases of pregnancy: since the 5th week and most of TVR fall (85 %) is seen at 16 weeks of gestation [3,4].
The lack of these hemodynamic changes seems to be correlated with an increased risk of pregnancy complications, such as pregnancy induced hypertension (PIH), preeclampsia (PE) and fetal growth restriction (FGR) [5].
Aim of this study is to analyse Total Vascular Resistance trend in the first and second trimester of pregnancy as a sign of maternal cardiovascular adaptation to pregnancy. The finding of high TVR values during the first and second trimester of pregnancy may indicate an abnormal vascular adaptation that might expose to a higher risk of complications.
Materials and Methods
An observational study was conducted at the San Giovanni Calibita Fatebenefratelli Hospital, Department of Obstetrics and Gynaecology in Rome over a continuous period from November 2011 to December 2012. Approval of the local ethics committee was obtained based on a submitted protocol, and informed consent was obtained from all patients prior to enrolment.
We enrolled 140 healthy, normotensive pregnant women during the first trimester of pregnancy (from 5+0 to 11+6 weeks of gestation) at their first check. All patients were subsequently evaluated at 16 and 22-23 weeks of gestation. We monitored maternal hemodynamics throughout the USCOM 1A (Ultrasonic Cardiac Output Monitor, Uscom Limited, Sydney, Australia), a non-invasive monitoring technology.
We retrospectively divided the study population in two groups:
Group A (n = 37): patients with TVR values persistently elevated at 22 weeks of gestation (> 1200 dyne/sec/cm-5)
Group B (n = 103): patients with a reduction of TVR values at 22 weeks of gestation (< 1200 dyne/sec/cm-5).
All patients were followed until the end of pregnancy to check for fetal-neonatal and maternal outcomes. Hypertensive disorders in pregnancy, as already mentioned by Larciprete and Montagnoli [6], was diagnosed according to the definition of ISSHP [7]: (1) preeclampsia: de novo hypertension (systolic blood pressure ≥ 140 mmHg and diastolic blood pressure ≥ 90 mmHg) after 20 wk of gestation associated with proteinuria. Proteinuria is defined as appearance of urinary protein greater than 300 mg/dl or a spot urine protein/dreatinine ratio ≥ 30 mg/mmol; (2) gestational hypertension: de novo hypertension alone after 20 wk of gestation; (3) chronic hypertension: hypertension diagnosed before 20 wk of gestation or preconception hypertension; (4) preeclampsia superimposed on chronic hypertension: in a woman with chronic hypertension, development of proteinuria and/or symptoms associated with preeclampsia after 20 wk of gestation.
Intrauterine Growth Restriction refers to a fetus with an estimated fetal weight < 10th percentile on ultrasound that, because of a pathologic process, has not attained its biologically determined growth potential [8].
Haemodynamic measurement
All haemodynamic measurements were acquired with the USCOM 1A. The USCOM has been validated against invasive gold standards and flow probes and has proof of effectiveness in pre-eclampsia [9-11]. USCOM uses continuous-wave Doppler to determine CO by a non-imaging transducer placed at the suprasternal notch to measure transaortic or transpulmonary blood flow. To calculate CO the transducer is placed in the suprasternal notch or in parasternal inter space, and the Doppler beam directed across the aortic or pulmonary valve to acquire a spectral Doppler flow profile displayed as a time-velocity plot. Once the optimal flow profile is obtained, the trace is frozen on the screen, and the flow profiles automatically traced allowing the stroke volume (SV) to be calculated as the product of the velocity-time integral and the cross-sectional area (CSA) of the chosen valve. The CSA of the aortic valve is determined from the proprietary height-indexed regression equations. The CO is then calculated from the product of the heart rate (HR) and SV. Input of blood pressure provides for calculation of TVR. We recorded, CO, SV, HR, Systolic Blood Pressure (SBP) and Diastolic Blood Pressure (DBP). All patients were examined following signed informed consent in accordance with the ethical approval.
Results
  Group A Group B p
Age (years) 32.56 ± 5.67 33.90 ± 5.97 ns
Height (m) 1.65 ± 0.13 1.65 ± 0.10 ns
Weight (kg) 60.23 ± 4.5 61.31 ± 5.6 ns
BMI (kg/m2) 22.05 ± 2.1 22.42 ± 2.4 ns
Table 1: Characteristics of study population.
Table 2 shows the average values of the heamodynamic parameters at 22-23 weeks of gestation Among 37 patients (26.5% of the total) with persistent high TVR values (>1200 dyne/sec/cm-5) at 22-23 weeks of gestation, 15 women (10% of the total) developed complications (7 patientsgestational hypertension, 3 patients preeclampsia and 5 pregnancies were complicated by intrauterine growth restriction). Among 103 patients of group B (73, 5 % of the total), 9 patients (6% of the total) developed complications (5 patients gestational hypertension, 3 patients preeclampsia and 1 patient intrauterine growth restriction).
  Group A (22 wks) Group B (22 wks) p
Cardiac Output (L/min) 5.45 ± 0.66 7.64 ± 1.44 < 0.01
Total Vascular Resistance (dyne/sec/cm-5) 1350.62 ± 211.5 915 ± 162.89 < 0.01
Heart Rate (bpm) 74.12 ± 11.3 81.86 ±8.2 < 0.01
Stroke Volume (mL) 74.62 ± 14.7 93.27± 10.3 < 0.01
Systolic Blood Pressure (mmHg) 124 ± 9.93 113.5 ± 10.54 < 0.01
Diastolic Blood Pressure (mmHg) 73.75 ± 10.08 70.71 ± 6.61 ns
Table 2: Hemodynamic features of study population at 22-23 weeks of gestation.
Figure 1 illustrates the TVR trend of the two groups of patients, since early pregnancy to 22 weeks of gestation. Group B shows a physiological decreasing trend of TVR at 22-23 weeks, the period in which vascular placental bed is considered fully completed. On the contrary, the other group of patients shows higher TVR values during the first weeks of gestation, a slight decrease at 16 weeks and a subsequent increase at 22-23 weeks (1350.62 ± 211.5 vs 915 ± 162.89 p < 0,01).
Figure 1: TVR trend between the two groups.
Figure 2 shows the Cardiac Output trend in the two groups. This parameter sharply increases in the group of patients with a reduction in TVR (Group B) as a compensation response ensuring a proper peripheral vascular filling. In the Group A we can notice an opposite trend with a progressive reduction in CO values. At 22-23 weeks of gestation there is a statistically significant difference in CO between the two groups (5.45 ± 0.66 vs 7.64 ± 1.44, p < 0, 01).
Figure 2: CO trend between the two groups.
Figures 3 and 4 shows the trend of stroke volume and heart rate that progressively increase in patients belonging to the Group B. This does not occur in the group A that shows a decrease in both stroke volume and heart rate.
Figure 3: SV trend between the two groups.

Figure 4: FHR trend between the two groups.
Both groups show a progressive decline in SBP and DBP even though this is more pronounced and significantly lower in the group of women with low TVR at 22-23 weeks (Figures 5-6).
Figure 5: SBP trend between the two groups.

Figure 6: DBP trend between the two groups.
Discussion
Pregnancy is characterized by important hemodynamic changes in order to promotematernal physiological cardiovascular adaptation. The introduction of USCOM has provided non invasive means for the evaluation of maternal cardiovascular adaptation. The accuracy of the system has been improved through numerous studies in laboratory, compared with other methods and in various clinical applications and has shown in a previous study the mean difference between observers was 0,16±0,59 l/min/m and Lin’s concordance correlation coefficient was 0,87 [12].
This study was designed to understand the evolution of maternal haemodynamics and determine if women at high risk of developing hypertensive complications in pregnancy could be identified prior to the clinical expression of pathological conditions.
The purpose of our study was to evaluate these hemodynamic changes during the first two trimesters of pregnancy. Our data showed that into 37 patients group (26.5% of the total) withpersistently elevated TVR values at 22-23 weeks, 15 women (10% of the total) experienced complications such as gestational hypertension, preeclampsia and intrauterine growth restriction. According to our data, a maternal hemodynamic condition characterized by persistently elevated TVR values (>1200 dyne/sec/cm-5) in the second trimester of pregnancy probably represents a risk factor for a poor fetal-maternal outcome.
From our results, the risk for developing hypertensive disorders or IUGR in patients with elevated TVR values in the second trimester of pregnancy is 1:25.
Our results show how the study of maternal vascular conditions during the first half of pregnancy is crucial in order to identify significant predictor for the onset of hypertensive disorders, such as gestational hypertension, preeclampsia and intrauterine growth restriction. The knowledge of this maternal condition allowed us to identify a group of so-called low-risk women with total vascular resistance values below 1000 dyne/sec/cm-5 that reflects the creation of an adequate low resistance and high capacitance vascular placental bed.
Similarly, high total vascular resistance values could be an early predictor of failure cardiovascular adaptation representing a high-risk group of pregnant women that need to be strictly monitored.
The results of this observational study warrant a more widespread trial to determine the outcomes benefit of a shift from blood pressure screening and blood pressure guided therapy to screening to direct Doppler ultrasound measures of stroke volume, cardiac output and total vascular resistance for prediction of negative outcomes and improved therapeutic guidance.
Conclusion
In conclusion, TVR might help to identify pregnant women at high risk of developing hypertensive complications even before the onset of elevated blood pressure values and clinical expression of pathological conditions.
Bibliography
  1. Novelli GP., et al. “Left ventricular concentric geometry as a risk factor in gestational hypertension”. Hypertension 41 (2003): 469-475.
  2. Valensise H., et al. “Maternal cardiac systolic and diastolic function: relationship with uteroplacental resistance. A Doppler and echicardiographic longitudinal study”. Ultrasound in Obstetrics & Gynaecology 15 (2000): 487-497.
  3. Clapp JF and Capeless E. “Cardiovascular function before, during, and after the first and subsequent pregnancies”. American Journal of Cardiology 80.11 (1997): 1469-1473.
  4. Robson SC., et al. “Serial study of factors influencing changes in cardiac output during human pregnancy”. American Journal of Physiology 136 (1989): H1060-1065.
  5. Dukevot JJ and Peeters LLH. “Maternal cardiovascular hemodymanic adaptation to pregnancy”. Obstetrical & Gynecological Survey 49.12 (1994): S1-S14.
  6. Montagnoli C and Larciprete G. “Preeclampsia: definitions, screening tools and diagnostic criteria in the supersonic era”. World Journal of Obstetrics and Gynecology 2014; 3 (3): 98-108.
  7. Brown MA, et al. “The classification and diagnosis of the hypertensive disorders of pregnancy: statement from the International Society for the Study of Hypertension in Pregnancy (ISSHP). Hypertension in Pregnancy 20.1 (2001): IX-XIV.
  8. A Lausman JK. “Intrauterine Growth Restriction: screening, diagnosis and management”. SOGC Guideline (2013).
  9. Phillips RA., et al. “Pulmonary artery catheter (PAC) accuracy and efficacy compared with flow probe and transcutaneous Doppler (USCOM): An ovine validation”. Critical Care Research and Practice (2012): 621496.
  10. Su BC., et al. “Reliability of A New Ultrasonic Cardiac Output Monitor in Recipients of Living Donor Liver Transplantation”. Liver Transplantation 14 (2008): 1029-1037.
  11. CC Kager., et al. “Measurement of cardiac output in normal pregnancy by a non-invasive two-dimensional independent Doppler device”. Australian and New Zealand Journal of Obstetrics and Gynaecology 49.2 (2009): 142-144.
  12. Dhanani S., “Intra-and-intra observer reliability using a non invasive ultrasound cardiac output monitor in healthy anesthetized children”. Pediatric Anesthesia 21.8 (2011): 858-864.
Copyright: © 2015 Lo Presti D., et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

PubMed Indexed Article

EC Pharmacology and Toxicology
LC-UV-MS and MS/MS Characterize Glutathione Reactivity with Different Isomers (2,2' and 2,4' vs. 4,4') of Methylene Diphenyl-Diisocyanate.

PMID: 31143884 [PubMed]

PMCID: PMC6536005


EC Pharmacology and Toxicology
Alzheimer's Pathogenesis, Metal-Mediated Redox Stress, and Potential Nanotheranostics.

PMID: 31565701 [PubMed]

PMCID: PMC6764777


EC Neurology
Differences in Rate of Cognitive Decline and Caregiver Burden between Alzheimer's Disease and Vascular Dementia: a Retrospective Study.

PMID: 27747317 [PubMed]

PMCID: PMC5065347


EC Pharmacology and Toxicology
Will Blockchain Technology Transform Healthcare and Biomedical Sciences?

PMID: 31460519 [PubMed]

PMCID: PMC6711478


EC Pharmacology and Toxicology
Is it a Prime Time for AI-powered Virtual Drug Screening?

PMID: 30215059 [PubMed]

PMCID: PMC6133253


EC Psychology and Psychiatry
Analysis of Evidence for the Combination of Pro-dopamine Regulator (KB220PAM) and Naltrexone to Prevent Opioid Use Disorder Relapse.

PMID: 30417173 [PubMed]

PMCID: PMC6226033


EC Anaesthesia
Arrest Under Anesthesia - What was the Culprit? A Case Report.

PMID: 30264037 [PubMed]

PMCID: PMC6155992


EC Orthopaedics
Distraction Implantation. A New Technique in Total Joint Arthroplasty and Direct Skeletal Attachment.

PMID: 30198026 [PubMed]

PMCID: PMC6124505


EC Pulmonology and Respiratory Medicine
Prevalence and factors associated with self-reported chronic obstructive pulmonary disease among adults aged 40-79: the National Health and Nutrition Examination Survey (NHANES) 2007-2012.

PMID: 30294723 [PubMed]

PMCID: PMC6169793


EC Dental Science
Important Dental Fiber-Reinforced Composite Molding Compound Breakthroughs

PMID: 29285526 [PubMed]

PMCID: PMC5743211


EC Microbiology
Prevalence of Intestinal Parasites Among HIV Infected and HIV Uninfected Patients Treated at the 1o De Maio Health Centre in Maputo, Mozambique

PMID: 29911204 [PubMed]

PMCID: PMC5999047


EC Microbiology
Macrophages and the Viral Dissemination Super Highway

PMID: 26949751 [PubMed]

PMCID: PMC4774560


EC Microbiology
The Microbiome, Antibiotics, and Health of the Pediatric Population.

PMID: 27390782 [PubMed]

PMCID: PMC4933318


EC Microbiology
Reactive Oxygen Species in HIV Infection

PMID: 28580453 [PubMed]

PMCID: PMC5450819


EC Microbiology
A Review of the CD4 T Cell Contribution to Lung Infection, Inflammation and Repair with a Focus on Wheeze and Asthma in the Pediatric Population

PMID: 26280024 [PubMed]

PMCID: PMC4533840


EC Neurology
Identifying Key Symptoms Differentiating Myalgic Encephalomyelitis and Chronic Fatigue Syndrome from Multiple Sclerosis

PMID: 28066845 [PubMed]

PMCID: PMC5214344


EC Pharmacology and Toxicology
Paradigm Shift is the Normal State of Pharmacology

PMID: 28936490 [PubMed]

PMCID: PMC5604476


EC Neurology
Examining those Meeting IOM Criteria Versus IOM Plus Fibromyalgia

PMID: 28713879 [PubMed]

PMCID: PMC5510658


EC Neurology
Unilateral Frontosphenoid Craniosynostosis: Case Report and a Review of the Literature

PMID: 28133641 [PubMed]

PMCID: PMC5267489


EC Ophthalmology
OCT-Angiography for Non-Invasive Monitoring of Neuronal and Vascular Structure in Mouse Retina: Implication for Characterization of Retinal Neurovascular Coupling

PMID: 29333536 [PubMed]

PMCID: PMC5766278


EC Neurology
Longer Duration of Downslope Treadmill Walking Induces Depression of H-Reflexes Measured during Standing and Walking.

PMID: 31032493 [PubMed]

PMCID: PMC6483108


EC Microbiology
Onchocerciasis in Mozambique: An Unknown Condition for Health Professionals.

PMID: 30957099 [PubMed]

PMCID: PMC6448571


EC Nutrition
Food Insecurity among Households with and without Podoconiosis in East and West Gojjam, Ethiopia.

PMID: 30101228 [PubMed]

PMCID: PMC6086333


EC Ophthalmology
REVIEW. +2 to +3 D. Reading Glasses to Prevent Myopia.

PMID: 31080964 [PubMed]

PMCID: PMC6508883


EC Gynaecology
Biomechanical Mapping of the Female Pelvic Floor: Uterine Prolapse Versus Normal Conditions.

PMID: 31093608 [PubMed]

PMCID: PMC6513001


EC Dental Science
Fiber-Reinforced Composites: A Breakthrough in Practical Clinical Applications with Advanced Wear Resistance for Dental Materials.

PMID: 31552397 [PubMed]

PMCID: PMC6758937


EC Microbiology
Neurocysticercosis in Child Bearing Women: An Overlooked Condition in Mozambique and a Potentially Missed Diagnosis in Women Presenting with Eclampsia.

PMID: 31681909 [PubMed]

PMCID: PMC6824723


EC Microbiology
Molecular Detection of Leptospira spp. in Rodents Trapped in the Mozambique Island City, Nampula Province, Mozambique.

PMID: 31681910 [PubMed]

PMCID: PMC6824726


EC Neurology
Endoplasmic Reticulum-Mitochondrial Cross-Talk in Neurodegenerative and Eye Diseases.

PMID: 31528859 [PubMed]

PMCID: PMC6746603


EC Psychology and Psychiatry
Can Chronic Consumption of Caffeine by Increasing D2/D3 Receptors Offer Benefit to Carriers of the DRD2 A1 Allele in Cocaine Abuse?

PMID: 31276119 [PubMed]

PMCID: PMC6604646


EC Anaesthesia
Real Time Locating Systems and sustainability of Perioperative Efficiency of Anesthesiologists.

PMID: 31406965 [PubMed]

PMCID: PMC6690616


EC Pharmacology and Toxicology
A Pilot STEM Curriculum Designed to Teach High School Students Concepts in Biochemical Engineering and Pharmacology.

PMID: 31517314 [PubMed]

PMCID: PMC6741290


EC Pharmacology and Toxicology
Toxic Mechanisms Underlying Motor Activity Changes Induced by a Mixture of Lead, Arsenic and Manganese.

PMID: 31633124 [PubMed]

PMCID: PMC6800226


EC Neurology
Research Volunteers' Attitudes Toward Chronic Fatigue Syndrome and Myalgic Encephalomyelitis.

PMID: 29662969 [PubMed]

PMCID: PMC5898812


EC Pharmacology and Toxicology
Hyperbaric Oxygen Therapy for Alzheimer's Disease.

PMID: 30215058 [PubMed]

PMCID: PMC6133268


News and Events

December Issue Release

We Always feel pleasure to share an update with you all. Here, notifying you that we have successfully released December issue for the respective journals and can be viewed in the current issue pages.

Submission Deadline for January Issue

E-Cronicon delightfully welcome all the authors around the globe for an effective collaboration with an article submission for the January issue of respective journals. Submissions are accepted on/before December 23, 2019.

Certificate of Publication

E-Cronicon honours with a "Publication Certificate" to the corresponding author by including the names of co-authors as a token of appreciation for publishing the work with our respective journals.

Best Article of the Issue

Editors of respective journals will always be very much interested in electing one Best Article after each issue release. The authors of the selected article will be honored with a "Best Article of the Issue" certificate.

Certifying for Review

E-Cronicon certify the Editors for their first review done towards assigned article of the respective journals.

Latest Articles

Latest articles will be updated immediately in the articles in press page of the respective journals.

Immediate Assistance

Prime moto of this team is to clarify all the queries without any delay or hesitation in order to avoid the inconvenience. For an immediate assistance on your queries please don't hesitate to drop an email to editor@ecronicon.uk