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Diastolic function in coronary artery disease
1Department of Medicine, University of Chicago.
Insights
Diastolic dysfunction in coronary artery disease involves impaired left ventricular filling due to acute ischemia or myocardial infarction. Key factors include altered relaxation and increased stiffness, impacting cardiac function.
Area of Science:
- Cardiology
- Cardiovascular Physiology
Background:
- Coronary artery disease (CAD) significantly impacts cardiac function, particularly diastolic function.
- Diastolic abnormalities manifest distinctly during acute ischemia and after myocardial infarction (MI).
Purpose of the Study:
- To review the pathophysiology of diastolic abnormalities in acute ischemia and post-myocardial infarction syndromes.
- To elucidate the mechanisms underlying altered left ventricular filling in CAD.
Main Methods:
- Review of existing clinical and experimental studies on diastolic function in CAD.
- Analysis of factors influencing the diastolic pressure-volume relation.
Main Results:
- Acute ischemia increases left ventricular filling pressures, potentially causing pulmonary edema.
- Silent ischemia results in a lesser increase in filling pressures compared to symptomatic ischemia.
- Post-MI, myocardial fibrosis elevates filling pressures, influenced by volume status.
- Diastolic dysfunction involves impaired myocardial relaxation and increased muscle stiffness, shifting the pressure-volume relation upwards.
Conclusions:
- Impaired myocardial relaxation is central to diastolic dysfunction during acute ischemia.
- Increased extracellular matrix, particularly collagen, leads to permanent muscle stiffness and chronic diastolic abnormalities in CAD.
Abstract:
Diastolic function in coronary artery disease is modified to a variable extent. There are distinct abnormalities produced during acute ischemia, and following myocardial infarction. The pathophysiology of diastolic abnormalities in these two syndromes is reviewed. During acute ischemia filling pressures of the left ventricle are increased. Pulmonary edema may be produced. Silent ischemia causes less of an increase in filling pressures. The diastolic pressure-volume relation is shifted in an upward manner with a variable contribution from altered myocardial relaxation, increased muscle stiffness, acute pericardial restriction, ventricular interaction, and acute chamber dilatation. The impairment of myocardial relaxation plays a central role and has been quantified in multiple clinical and experimental studies. Filling of the left ventricle during ischemia is altered due to the factors which shift the pressure-volume relation. The acute increase in left atrial pressure may increase filling rates somewhat surprisingly, given the reduced left ventricular compliance. Myocardial fibrosis following infarction may elevate filling pressures, but the degree of elevation is closely tied to the intravascular volume status. Shifts in the diastolic pressure-volume relation reflect a loss of chamber compliance due to an increase in muscle stiffness. Increased amounts of extracellular matrix, specifically collagen, produce this permanent increase in muscle stiffness which is central to the diastolic abnormalities in chronic coronary artery disease.