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Insights into the effect of myocardial revascularisation on electrical and mechanical cardiac function
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine. (Cardiology)
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background: Acute coronary syndrome is known for its effect on cardiac function and can lead to impaired segmental and even global myocardial function. Evidence exists that myocardial revascularisation whether pharmacological, interventional or surgical results in improvement of systolic and diastolic left ventricular (LV) function, particularly that of the long axis which represents the sub-endocardial function, known as the most sensitive layer to ischaemia.

Objective: We sought to gain more insight into the early effect of pharmacological and interventional myocardial revascularisation on various aspects of cardiac function including endocrine, electrical, segmental, twist, right ventricular (RV) and left atrial (LA) function. In particular, we aimed to assess the response of ventricular electromechanical function to thrombolysis and its relationship with peptides levels. We also investigated the behaviour of RV function in the setting of LV inferior myocardial infarction (IMI) during the acute insult and early recovery. In addition, we aimed to assess in detail LA electrical and mechanical function in such patients. Finally, we studied the early effect of surgical revascularisation on the LV mechanics using the recent novel of speckle tracking echocardiography technology to assess rotation, twist and torsion and the strain deformation parameters as a tool of identifying global ventricular function.

Methods: We used conventionally Doppler echocardiographic transthoracic techniques including M-mode, 2-Dimentional, myocardial tissue Doppler, and speckle tracking techniques. Commercially available SPSS as a software was used for statistical analysis.

Results: 1-The elevated peptide levels at 7 days post-myocardial infarction correlated with the reduced mechanical activity of the adjacent non-infarcted segment thus making natriuretic peptides related to failure of compensatory hyperdynamic activity of the non-infarcted area rather than the injured myocardial segments. 2-RV segmental and global functions were impaired in acute IMI, and recovered in 87% of patients following thrombolysis. In the absence of clear evidence for RV infarction the disturbances in the remaining 13% may represent stunned myocardium with its known delayed recovery. 3-LA electromechanical function was impaired in acute inferior STEMI and improved after thrombolysis. The partial functional recovery suggests either reversible ischaemic pathology or a response to a non-compliant LV segment. The residual LA electromechanical and pump dysfunction suggest intrinsic pathology, likely to be ischaemic in origin. 4-LV function was maintained in a group of patients with multivessel coronary artery disease who underwent coronary artery bypass graft (CABG) surgery. Surgical myocardial revascularisation did not result in any early detectable change in the three functional components of the myocardium, including twist and torsion, as opposite to conventional percutaneous coronary intervention (PCI).

Conclusion: The studied different materials in this thesis provide significant knowledge on various aspects of acute ischaemic cardiac pathology and early effect of revascularisation. The use of non-invasive imaging, particularly echocardiography with its different modalities, in studying such patients should offer immediate thorough bed-side assessment and assist in offering optimum management.

Place, publisher, year, edition, pages
Umeå: Umeå universitet , 2012. , 95 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1500
Keyword [en]
myocardial infarction, natriuretic peptides, echocardiography, ventricular function, atrial function, surgical revascularisation, speckle tracking echocardiography
National Category
Cardiac and Cardiovascular Systems
Research subject
Cardiology
Identifiers
URN: urn:nbn:se:umu:diva-54674ISBN: 978-91-7459-423-2 (print)OAI: oai:DiVA.org:umu-54674DiVA: diva2:525101
Public defence
2012-06-07, Room D, Unod T9, Umeå University Hospital, Umeå, 09:00 (English)
Opponent
Supervisors
Available from: 2012-05-16 Created: 2012-05-05 Last updated: 2012-05-25Bibliographically approved
List of papers
1. Ventricular endocrine and mechanical function following thrombolysis for acute myocardial infarction
Open this publication in new window or tab >>Ventricular endocrine and mechanical function following thrombolysis for acute myocardial infarction
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2007 (English)In: International Journal of Cardiology, ISSN 0167-5273, E-ISSN 1874-1754, Vol. 117, no 1, 51-58 p.Article in journal (Refereed) Published
Abstract [en]

Objective The objective of this study was to assess natriuretic peptide release following acute myocardial infarction, and its relationship with ventricular function. Methods A total of 44 patients with acute myocardial infarction were studied; 13 anterior, age (57 Â± 12 years) and 31 inferior, age (58 Â± 12 years). Peptide levels and left ventricular function by echocardiography were assessed at admission and on days 7 and 30 after thrombolysis. Healthy volunteers (n = 21) served as controls. Results Atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) levels rose from admission to day 7 (p = 0.002). While ANP remained elevated at day 30 in both groups, BNP levels fell in patients with anterior myocardial infarction (p = 0.03). Left ventricular fractional shortening was reduced at admission in the two groups (p = 0.01) but returned towards normal in 7 days (p = 0.001) in inferior myocardial infarction and in 30 days in anterior myocardial infarction (p = 0.02). Left ventricular long axis amplitude was universally reduced at admission (p = 0.01) and remained abnormal at day 30 (p = 0.01) in both groups. At day 7, BNP and ANP levels inversely correlated with long axis amplitude of lateral wall in anterior myocardial infarction; (r = âˆ’ 0.7, p = 0.01). BNP correlated inversely with fractional shortening in anterior myocardial infarction (r = âˆ’ 0.7, p = 0.01) at day 30. Conclusion The elevated peptide levels at 7 days post-myocardial infarction correlate with reduced mechanical activity of the adjacent noninfarcted segment. Natriuretic peptides release seem to be related to failure of compensatory hyperdynamic activity of the noninfarcted area rather than directly from the injured myocardial segments.

Keyword
Myocardial infarction, Ventricular function, Natriuretic peptides, Thrombolysis
Identifiers
urn:nbn:se:umu:diva-53471 (URN)10.1016/j.ijcard.2006.04.052 (DOI)
Available from: 2012-03-28 Created: 2012-03-28 Last updated: 2017-12-07Bibliographically approved
2. Right ventricular stunning in inferior myocardial infarction.
Open this publication in new window or tab >>Right ventricular stunning in inferior myocardial infarction.
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2008 (English)In: International journal of cardiology, ISSN 1874-1754Article in journal (Refereed) Published
Abstract [en]

AIM: To assess right ventricular (RV) function in patients with inferior myocardial infarction (IMI) and to observe changes following thrombolysis. BACKGROUND: RV dysfunction occurs in 30% of patients with IMI. The extent of such involvement and its potential, recovery has not been determined. METHODS: We studied 30 patients with acute IMI (age 56+/-12 years), on admission, day 7 and day 30 post thrombolysis. No patient had clinical signs of RV failure. RV segmental function was assessed from free wall long axis and global function from filling and ejection velocities. Values were compared with 15 age-matched controls. RESULTS: On admission, RV long axis amplitude, systolic and diastolic velocities were depressed (2.09+/-0.39 vs 2.6+/-0.3 cm, 8.18+/-1.8 vs 10.0+/-2.0 cm/s and 6.9+/-2.7 vs 10.0+/-2.5 cm/s, p<0.01 for all) and global function impaired; reduced Z ratio (0.85+/-0.07 vs 0.9+/-0.04, p<0.01), raised Tei index (0.49+/-0.26 vs 0.3+/-0.1, p<0.001) and prolonged t-IVT (8.16+/-3.9 vs 4.8+/-2 s/m, p<0.01) compared to controls. After thrombolysis, RV long axis amplitude (2.28+/-0.3 cm, p<0.05), systolic velocity (10.0+/-2.7 cm/s, p<0.01), early diastolic velocity (8.3+/-2.16, p<0.05), Z ratio (0.9+/-0.05, p<0.01), Tei index (0.34+/-0.17, p<0.01) and t-IVT (6.2+/-2.7 s/m, p<0.05) all normalised at day 30. Only 4 (13%) patients remained with RV long axis amplitude and one with t-IVT and Tei index values outside the normal 95% CI at day 30. RV inflow diameter and tricuspid regurgitation did not change. CONCLUSION: In IMI, RV segmental and global functions are acutely impaired, and recover in 87% of patients following thrombolysis. In the absence of clear evidence for RV infarction the disturbances in the remaining 13% may represent stunned myocardium that may demonstrate delayed recovery.

Identifiers
urn:nbn:se:umu:diva-22859 (URN)10.1016/j.ijcard.2008.05.021 (DOI)18687491 (PubMedID)
Available from: 2009-05-19 Created: 2009-05-19 Last updated: 2012-05-16
3. Electromechanical left atrial disturbances in acute inferior myocardial infarction: an evidence for ischaemic dysfunction
Open this publication in new window or tab >>Electromechanical left atrial disturbances in acute inferior myocardial infarction: an evidence for ischaemic dysfunction
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2011 (English)In: International Journal of Cardiology, ISSN 0167-5273, E-ISSN 1874-1754, Vol. 151, no 1, 96-98 p.Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Amsterdam: Elsevier/North Holland, 2011
Keyword
Left atrial function, Acute myocardial infarction, Thrombolytic therapy, Echocardiography
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:umu:diva-45880 (URN)10.1016/j.ijcard.2011.05.040 (DOI)21641055 (PubMedID)
Available from: 2011-08-19 Created: 2011-08-19 Last updated: 2017-12-08Bibliographically approved
4. Early effect of surgical revascularisation on left ventricular twist function
Open this publication in new window or tab >>Early effect of surgical revascularisation on left ventricular twist function
2015 (English)In: International Cardiovascular Forum Journal, ISSN 2410-2636, Vol. 4, 16-23 p.Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Barcaray Publishing, 2015
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:umu:diva-55469 (URN)10.17987/icfj.v4i0,125 (DOI)
Available from: 2012-05-16 Created: 2012-05-16 Last updated: 2016-05-11Bibliographically approved

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