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Quantification of left-to-right shunt through Patent Ductus Arteriosus by colour Doppler

Harling, Solweig LU (2011) In Lund University, Faculty of Medicine Doctoral Dissertation Series 2011:86.
Abstract (Swedish)
Popular Abstract in Swedish

Ductus arteriosus är ett kärl som finns hos foster för att styra blodet förbi lungorna. Kärlet stänger sig normalt inom 3 dagar efter födelsen men kan kvarstå öppet framför allt hos mycket för tidigt födda barn. Vid födelsen leder tryckförändringar i cirkulationen till att flödet i ductus vänder och blodet styrs istället till lungorna. Flödet genom ductus hos för tidigt födda barn kan vara mycket skadligt varför detta behandlas med medicin som stänger kärlet. Alternativt används kirurgi vid utebliven effekt av medicinen.

Huvudsyftet med inkluderade studier har varit att utveckla en metod att med hjälp av ultraljud storleksbedöma hur mycket blod som styrs genom ductus arteriosus till... (More)
Popular Abstract in Swedish

Ductus arteriosus är ett kärl som finns hos foster för att styra blodet förbi lungorna. Kärlet stänger sig normalt inom 3 dagar efter födelsen men kan kvarstå öppet framför allt hos mycket för tidigt födda barn. Vid födelsen leder tryckförändringar i cirkulationen till att flödet i ductus vänder och blodet styrs istället till lungorna. Flödet genom ductus hos för tidigt födda barn kan vara mycket skadligt varför detta behandlas med medicin som stänger kärlet. Alternativt används kirurgi vid utebliven effekt av medicinen.

Huvudsyftet med inkluderade studier har varit att utveckla en metod att med hjälp av ultraljud storleksbedöma hur mycket blod som styrs genom ductus arteriosus till lungorna.

Det finns ingen enhetlig behandlingsstrategi för prematurfödda barn med skadligt flöde genom ductus. Då läkemedel som används för slutning av ductus arteriosus, speciellt indomethacin, har allvarliga biverkningar måste man noga överväga behandlingen.

I vår djurstudie av lamm visade vi att indomethacin reducerar flödet i hjärtats kranskärl i upp till 50 %, en effekt som kunde sitta i upp till en timme. I en djurmodell har vi utvecklat en icke invasiv metod för storleksbedömning av blodflödet genom ductus arteriosus. Flödet i aorta och genom ductus mättes med flödesmätare placerade runt kärlen samtidigt som ultraljudsregistreringar gjordes över lungpulsåderns huvudstam med inkommande ductusflöde. Ductusflödet, som i en ultraljudsbild presenteras som färgpixlar, kvantifierades som procent färgpixlar/ytenhet, där ytan avgränsades med anatomiska landmärken. Där fanns en signifikant korrelation mellan uppmätt flöde till lungorna (shuntstorlek) och procent färgpixlar/ytenhet som blev mer signifikant när enbart gröna pixlar jämfördes med flödet. När shuntstorleken var ≥1.5:1 så täcktes mer än ≥ 50 % av den uppmätta ytan av färgpixlar. I vår kliniska studie av barn som skulle genomgå ductus stängning med device hade metoden en sensitivitet på 92 % hos barn med en shunt ≥ 1.5.

Vi visar också att inflammation under barnets 3 första levnadsdygn inte ökar risken för utvecklandet av öppen ductus med skadligt flöde som behöver behandlas men att dessa barn får lägre blodtryck och vidgning av ductuskärlet.

Vi föreslår att vår metod på ett enkelt och säkert sätt kan användas för att bedöma storleken av flödet genom ductus. Att använda uppmätt shuntstorlek > 1.5:1 som vägledning för behandling kan minska antalet onödiga behandlingar samt komplikationer till följd av dessa. (Less)
Abstract
The aim of this thesis was to develop a non-invasive method to quantify the size of a shunt through a patent ductus arteriosus (PDA) by ultrasound and to test its usability in clinical settings. There is no consensus regarding the optimal management strategy for a PDA in premature infants. Non-steroidal anti-inflammatory drugs (NSAID) are the first treatment of choice. The use of NSAIDs, especially indomethacin, should be carefully balanced, as they have their disadvantages. In our experimental study in lambs, indomethacin acutely reduced the coronary flow by up to 50% and the effect lasted for up to one hour. In our lamb model, we developed a non-invasive method to quantify the ductal shunt by ultrasound. The flow was measured with... (More)
The aim of this thesis was to develop a non-invasive method to quantify the size of a shunt through a patent ductus arteriosus (PDA) by ultrasound and to test its usability in clinical settings. There is no consensus regarding the optimal management strategy for a PDA in premature infants. Non-steroidal anti-inflammatory drugs (NSAID) are the first treatment of choice. The use of NSAIDs, especially indomethacin, should be carefully balanced, as they have their disadvantages. In our experimental study in lambs, indomethacin acutely reduced the coronary flow by up to 50% and the effect lasted for up to one hour. In our lamb model, we developed a non-invasive method to quantify the ductal shunt by ultrasound. The flow was measured with electromagnetic flow meters in the ascending aorta and in the ductus and a colour Doppler image was obtained simultaneously over the main pulmonary artery longitudinal cross-section including ductal inflow. The percentage of colour pixels representing ductal flow was quantified in the main pulmonary artery outlined by anatomic landmarks. There was a correlation between the ratio of pulmonary to systemic flow (Qp/Qs) and the percentage of total colours covering the cross-section and there was an even better correlation with green pixels alone. When the Qp/Qs was ≥ 1.5:1, the percentage of green pixels in PALS was ≥ 50. In children admitted for the device closure of the open ductus, the method had 92% sensitivity for a measured Qp/Qs of ≥ 1.5. In preterm infants during the first three days of life, the ductal diameter but not the quantified ductal shunt predicted the need for treatment. We showed further that the perinatal cytokine burden during the first three days of life is not associated with an increased need to close the ductus, but it is associated with increased ductal diameter and reduced systolic blood pressure.

We suggest that our method could be used as a non-invasive tool to determine a haemodynamically significant ductal shunt. Using the evaluated Qp/Qs of > 1.5:1 as a guide for treatment decisions might reduce the need for unnecessary interventions and reduce complications. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Tulzer, Gerald, Kinder-Kardiologie, Kinderherzzentrum, Linz, Österreich
organization
publishing date
type
Thesis
publication status
published
subject
in
Lund University, Faculty of Medicine Doctoral Dissertation Series
volume
2011:86
pages
109 pages
publisher
Department of Paediatrics, Lund University
defense location
Segerfalkssalen, WNC, Skåne University Hospital, Lund
defense date
2011-09-23 13:00
ISSN
1652-8220
ISBN
978-91-7473-155-2
language
English
LU publication?
yes
id
96ca1246-f18d-4e2b-a11c-b7312d8aad83 (old id 2065161)
date added to LUP
2011-08-24 09:53:45
date last changed
2016-09-19 08:44:49
@phdthesis{96ca1246-f18d-4e2b-a11c-b7312d8aad83,
  abstract     = {The aim of this thesis was to develop a non-invasive method to quantify the size of a shunt through a patent ductus arteriosus (PDA) by ultrasound and to test its usability in clinical settings. There is no consensus regarding the optimal management strategy for a PDA in premature infants. Non-steroidal anti-inflammatory drugs (NSAID) are the first treatment of choice. The use of NSAIDs, especially indomethacin, should be carefully balanced, as they have their disadvantages. In our experimental study in lambs, indomethacin acutely reduced the coronary flow by up to 50% and the effect lasted for up to one hour. In our lamb model, we developed a non-invasive method to quantify the ductal shunt by ultrasound. The flow was measured with electromagnetic flow meters in the ascending aorta and in the ductus and a colour Doppler image was obtained simultaneously over the main pulmonary artery longitudinal cross-section including ductal inflow. The percentage of colour pixels representing ductal flow was quantified in the main pulmonary artery outlined by anatomic landmarks. There was a correlation between the ratio of pulmonary to systemic flow (Qp/Qs) and the percentage of total colours covering the cross-section and there was an even better correlation with green pixels alone. When the Qp/Qs was ≥ 1.5:1, the percentage of green pixels in PALS was ≥ 50. In children admitted for the device closure of the open ductus, the method had 92% sensitivity for a measured Qp/Qs of ≥ 1.5. In preterm infants during the first three days of life, the ductal diameter but not the quantified ductal shunt predicted the need for treatment. We showed further that the perinatal cytokine burden during the first three days of life is not associated with an increased need to close the ductus, but it is associated with increased ductal diameter and reduced systolic blood pressure.<br/><br>
We suggest that our method could be used as a non-invasive tool to determine a haemodynamically significant ductal shunt. Using the evaluated Qp/Qs of &gt; 1.5:1 as a guide for treatment decisions might reduce the need for unnecessary interventions and reduce complications.},
  author       = {Harling, Solweig},
  isbn         = {978-91-7473-155-2},
  issn         = {1652-8220},
  language     = {eng},
  pages        = {109},
  publisher    = {Department of Paediatrics, Lund University},
  school       = {Lund University},
  series       = {Lund University, Faculty of Medicine Doctoral Dissertation Series},
  title        = {Quantification of left-to-right shunt through Patent Ductus Arteriosus by colour Doppler},
  volume       = {2011:86},
  year         = {2011},
}