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Dissociation between global and regional systolic and diastolic ventricular function during coronary occlusion and
M S Verani1, R Bolli, S Tadros
1Department of Internal Medicine, Baylor College of Medicine, Methodist Hospital, Houston, TX 77030.
Insights
Global ventricular function indexes like ejection fraction (EF) do not reflect slow regional recovery after myocardial infarction reperfusion. Regional function recovery is delayed compared to global measures in stunned myocardium.
Area of Science:
- Cardiology
- Myocardial Infarction Research
- Cardiac Function Assessment
Background:
- Global ventricular function indexes, such as ejection fraction (EF) and peak diastolic filling rate (PDFR), are commonly used to evaluate myocardial infarction treatment.
- Assessing regional myocardial function provides a more detailed understanding of cardiac performance post-infarction.
Purpose of the Study:
- To investigate the relationship between global ventricular function indexes and regional function indexes during coronary occlusion and reperfusion.
- To determine if global indexes accurately reflect the recovery of stunned myocardium after reperfusion.
Main Methods:
- Utilized a computerized nuclear cardiac probe to measure global indexes (EF, PDFR) in open-chest dogs.
- Employed Doppler ultrasonic wall-thickening probes to assess regional myocardial function.
- Monitored cardiac function during 15 minutes of coronary occlusion and 120 minutes of reperfusion.
Main Results:
- During occlusion, EF and PDFR decreased significantly, showing similar directional changes to regional function.
- Following reperfusion, EF and PDFR rapidly improved to baseline levels.
- Regional systolic and diastolic function recovered slowly and remained abnormal throughout the reperfusion period, poorly correlating with global index recovery.
Conclusions:
- Global ventricular function indexes do not accurately represent the slow recovery of regional myocardial function after reperfusion.
- The rapid improvement in global indexes during reperfusion may mask the persistent dysfunction of the stunned myocardium.
Abstract:
Indexes of global ventricular function such as the ejection fraction (EF) and the peak diastolic filling rate (PDFR) are often used to assess the effects of coronary recanalization in patients with myocardial infarction. In this investigation we assessed the relationship between these global indexes and directly measured indexes of regional function during 15 minutes of coronary occlusion followed by 120 minutes of reperfusion in 22 open-chest dogs. A computerized nuclear cardiac probe was used to assess EF and PDFR. Indexes of regional function were measured by Doppler ultrasonic wall-thickening probes. During coronary occlusion, paradoxical systolic thinning occurred and the EF and PDFR decreased an average of 31.6% and 24.4%, respectively. During reperfusion the EF and PDFR improved rapidly and at 60 minutes were similar to baseline. Systolic wall thickening improved more gradually and remained abnormal throughout reperfusion. Likewise, indexes of diastolic function (mean rate to half end-diastolic thinning and late diastolic thinning fraction) recovered slowly and remained abnormal throughout reperfusion (78% and 69.7%, respectively). The correlation between the rate of change of global and regional function was poor during both coronary occlusion and reperfusion. Thus, during coronary occlusion the global and regional indexes of ventricular function undergo directionally similar changes. However, during coronary reperfusion the global indexes do not reflect the slow recovery of the stunned myocardium.