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Insights into the effect of myocardial revascularisation on electrical and mechanical cardiac function

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.

Identiferoai:union.ndltd.org:UPSALLA1/oai:DiVA.org:umu-54674
Date January 2012
CreatorsRamzy Guirguis, Ihab
PublisherUmeå universitet, Institutionen för folkhälsa och klinisk medicin, Umeå : Umeå universitet
Source SetsDiVA Archive at Upsalla University
LanguageEnglish
Detected LanguageEnglish
TypeDoctoral thesis, comprehensive summary, info:eu-repo/semantics/doctoralThesis, text
Formatapplication/pdf
Rightsinfo:eu-repo/semantics/openAccess
RelationUmeå University medical dissertations, 0346-6612 ; 1500

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