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Non-Invasive Measures of Heart Failure

Kanski, Mikael LU (2015) In Lund University, Faculty of Medicine Doctoral Dissertation Series 2015:68.
Abstract (Swedish)
Popular Abstract in Swedish

Hjärtsvikt är en sjukdom som beror på att hjärtat inte kan pumpa ut tillräckligt med blod till kroppens vävnader. I Sverige drabbas årligen 30000 personer av hjärtsvikt, och prognosen är jämförbar med de vanligaste cancerformerna. Trots att det är så vanligt och allvarligt, saknas i dagsläget objektiva mått på hjärtsvikt – det finns alltså ingen ”linjal” för att mäta hur mycket hjärtsvikt en patient har. Den vanligaste graderingen av hjärtsvikt är New York Heart Associations (NYHA) skala, som utgår från vid vilken fysisk aktivitet som patienten får besvär på grund av hjärtats oförmåga att leverera blod till kroppen. Skalan sträcker sig från klass I (ingen begränsning) till klass IV (besvär vid... (More)
Popular Abstract in Swedish

Hjärtsvikt är en sjukdom som beror på att hjärtat inte kan pumpa ut tillräckligt med blod till kroppens vävnader. I Sverige drabbas årligen 30000 personer av hjärtsvikt, och prognosen är jämförbar med de vanligaste cancerformerna. Trots att det är så vanligt och allvarligt, saknas i dagsläget objektiva mått på hjärtsvikt – det finns alltså ingen ”linjal” för att mäta hur mycket hjärtsvikt en patient har. Den vanligaste graderingen av hjärtsvikt är New York Heart Associations (NYHA) skala, som utgår från vid vilken fysisk aktivitet som patienten får besvär på grund av hjärtats oförmåga att leverera blod till kroppen. Skalan sträcker sig från klass I (ingen begränsning) till klass IV (besvär vid minsta lilla fysiska aktivitet). Målet med arbetet i denna avhandling är att utveckla ett nytt mått på hjärtsvikt med hjälp av magnetkamera (MR). De metoder som används är 2D-flöde och så kallat 4D-flöde. Det sistnämnda innebär att flödet mäts inte bara genom ett plan, utan i alla riktningar i en volym.

Vid hjärtsvikt kommer blodflödet genom hjärtat att begränsas, vilket leder till ökat tryck i lungkretsloppet (lilla kretsloppet). Vår hypotes var att detta skulle leda till ökad blodvolym i lilla kretsloppet och stelare kärl till följd av töjning. Detta undersöktes först i studie I hos grisar vars hjärtmuskel försvagats genom inducerad hjärtinfarkt. Vi fann att blodvolymen var oförändrad av infarkten, men fann också indikation på att kärlen blev stelare. Detta togs som ett tecken på att graden av stelhet kan vara ett mått på hjärtsvikt. I studie II undersöktes patienter med systemisk skleros. Dessa patienter löper risk att utveckla hjärtsvikt och förhöjt blodtryck på grund av kärlförändringar i lungorna. Resultaten visade ingen skillnad i kärlens stelhet jämfört med friska försökspersoner. Dock befanns patienterna ha en lägre mängd blod i lungkretsloppet, vilket skulle kunna bero på tidiga kärlförändringar. I studie III jämfördes olika typer av 4D-flöden. För att få så skarpa bilder som möjligt används ofta en ”navigator” som gör att man tar bilder när hjärtat befinner sig inom ett specifikt läge. En nackdel är att undersökningstiden förlängs markant. Därför studerades möjligheten att få bra kvalitet på 4D-flödesdata även utan navigator. Resultaten visar att man kan samla in avancerad 4D-data som blodets rörelseenergi inuti hjärtat utan navigator av lika god kvalitet som med navigator. Detta förenklar undersökning av patienter med hjärtsvikt, som kan ha svårt att ligga under en längre tid. I studie IV undersöktes rörelseenergin inuti hjärtat hos patienter med hjärtsvikt. Jämfört med friska försökspersoner har blodflödet hos patienter högre energi inuti hjärtat, vilket innebär att energi ej används optimalt. Dessutom kunde patienterna delas in i tre olika energimönster. Klassificering av energimönster skulle kunna vara en ny metod för gradering av förhöjt tryck i lilla kretsloppet och hjärtsvikt. (Less)
Abstract
Heart failure is a clinical syndrome characterized by an inability of the heart to meet the metabolic demands of the body. Approximately 1-2% of the population in the western society has the diagnosis, and the 5-year mortality rate is comparable with the common cancer diagnoses. The lack of reliable objective measures of heart failure motivates research in this direction. Blood flow is an essential parameter in hemodynamics and it can be expected that the blood flow is altered in patients with heart failure. A possible scenario is that backward failure could lead to increased pulmonary blood volume (PBV), which in turn could reduce the variation in PBV variation (PBVV). Using magnetic resonance imaging (MRI) it is possible to measure blood... (More)
Heart failure is a clinical syndrome characterized by an inability of the heart to meet the metabolic demands of the body. Approximately 1-2% of the population in the western society has the diagnosis, and the 5-year mortality rate is comparable with the common cancer diagnoses. The lack of reliable objective measures of heart failure motivates research in this direction. Blood flow is an essential parameter in hemodynamics and it can be expected that the blood flow is altered in patients with heart failure. A possible scenario is that backward failure could lead to increased pulmonary blood volume (PBV), which in turn could reduce the variation in PBV variation (PBVV). Using magnetic resonance imaging (MRI) it is possible to measure blood flow non-invasively with excellent accuracy, and both PBV and PBVV can be quantified using 2D-flow MRI. Furthermore, the intracardiac flow patterns have previously been found altered in heart failure. This can be assessed in detail by means of time-resolved three-directional (4D-flow) MRI. The results of the present work confirm the potential of MRI in this context. In study I, we found that the PBVV decreased by approximately 60% after experimentally induced myocardial infarction in pigs. This was interpreted as a consequence of stiffened vessels in the pulmonary circulation due to backward failure. However, contrary to our expectations, no difference was found in PBV. In study II we explored if patients with systemic sclerosis (SSc), who have an increased risk for developing pulmonary arterial hypertension and heart failure, had altered PBV and PBVV compared to healthy controls. We found no difference in PBVV, but a lower PBV indexed to lung volume in patients with SSc. This was interpreted as signs of early vascular changes in patients with SSc, however with preserved vascular distensibility. In study III we investigated the possibility to acquire 4D-flow data without respiratory navigator. The respiratory navigator is used to reduce motion artifacts. This is achieved, however, at the cost of prolonged scan time, which can be problematic for orthopneic patients. We found that the data quality of intracardiac measures are similar when acquired without as with the respiratory navigator. In study IV we explored whether the kinetic energy (KE) and the KE patterns measured using 4D-flow technique differ between patients with heart failure and controls. The results show that the KE indexed to stroke volume (SV) and cardiac index (CI) is higher in patients, indicating wasteful flow conditions accompanying heart failure. Moreover, we found that patients with heart failure present three distinct KE patterns, unrelated to current staging methods. This means that KE pattern analysis may be a conceptually new approach to staging and quantifying heart failure. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Axel, Leon, Department of Radiology, New York University School of Medicine, New York, NY, USA
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Heart failure, diagnosis, magnetic resonance imaging, blood flow, 4D flow, pulmonary blood volume, kinetic energy
in
Lund University, Faculty of Medicine Doctoral Dissertation Series
volume
2015:68
pages
69 pages
publisher
Department of Clinical Physiology, Lund University
defense location
Föreläsningssal 3 (F3), Blocket, Skånes Universitetssjukhus, Lund
defense date
2015-05-30 09:00
ISSN
1652-8220
ISBN
978-91-7619-147-7
language
English
LU publication?
yes
id
51681ceb-7dce-4522-916d-42aac0e38b75 (old id 5367091)
date added to LUP
2015-05-08 12:21:41
date last changed
2016-09-19 08:44:51
@phdthesis{51681ceb-7dce-4522-916d-42aac0e38b75,
  abstract     = {Heart failure is a clinical syndrome characterized by an inability of the heart to meet the metabolic demands of the body. Approximately 1-2% of the population in the western society has the diagnosis, and the 5-year mortality rate is comparable with the common cancer diagnoses. The lack of reliable objective measures of heart failure motivates research in this direction. Blood flow is an essential parameter in hemodynamics and it can be expected that the blood flow is altered in patients with heart failure. A possible scenario is that backward failure could lead to increased pulmonary blood volume (PBV), which in turn could reduce the variation in PBV variation (PBVV). Using magnetic resonance imaging (MRI) it is possible to measure blood flow non-invasively with excellent accuracy, and both PBV and PBVV can be quantified using 2D-flow MRI. Furthermore, the intracardiac flow patterns have previously been found altered in heart failure. This can be assessed in detail by means of time-resolved three-directional (4D-flow) MRI. The results of the present work confirm the potential of MRI in this context. In study I, we found that the PBVV decreased by approximately 60% after experimentally induced myocardial infarction in pigs. This was interpreted as a consequence of stiffened vessels in the pulmonary circulation due to backward failure. However, contrary to our expectations, no difference was found in PBV. In study II we explored if patients with systemic sclerosis (SSc), who have an increased risk for developing pulmonary arterial hypertension and heart failure, had altered PBV and PBVV compared to healthy controls. We found no difference in PBVV, but a lower PBV indexed to lung volume in patients with SSc. This was interpreted as signs of early vascular changes in patients with SSc, however with preserved vascular distensibility. In study III we investigated the possibility to acquire 4D-flow data without respiratory navigator. The respiratory navigator is used to reduce motion artifacts. This is achieved, however, at the cost of prolonged scan time, which can be problematic for orthopneic patients. We found that the data quality of intracardiac measures are similar when acquired without as with the respiratory navigator. In study IV we explored whether the kinetic energy (KE) and the KE patterns measured using 4D-flow technique differ between patients with heart failure and controls. The results show that the KE indexed to stroke volume (SV) and cardiac index (CI) is higher in patients, indicating wasteful flow conditions accompanying heart failure. Moreover, we found that patients with heart failure present three distinct KE patterns, unrelated to current staging methods. This means that KE pattern analysis may be a conceptually new approach to staging and quantifying heart failure.},
  author       = {Kanski, Mikael},
  isbn         = {978-91-7619-147-7},
  issn         = {1652-8220},
  keyword      = {Heart failure,diagnosis,magnetic resonance imaging,blood flow,4D flow,pulmonary blood volume,kinetic energy},
  language     = {eng},
  pages        = {69},
  publisher    = {Department of Clinical Physiology, Lund University},
  school       = {Lund University},
  series       = {Lund University, Faculty of Medicine Doctoral Dissertation Series},
  title        = {Non-Invasive Measures of Heart Failure},
  volume       = {2015:68},
  year         = {2015},
}