Clinical Study Of Detection Of Left Anterior Descending Coronary Artery Stenosis And Evaluation Of Local Haemodynamic Changes Before And After The Left Anterior Descending Coronary Artery Stent Implantation By Transthoracic Color Doppler Echocardiography

PART I. Value of transthoracic coronary color Doppler echocardiography in the diagnosis of left anterior descending coronary artery stenosisObjectives To evaluate the value of localized acceleration flow andretrograde flow detected by transthoracic color Doppler echocardiography in the diagnosis of LAD (Left Anterior Descending Coronary Artery) stenosis, and to explore the effects of stenosis on local haemodynamics and the value of the haemodynamic parameters in the diagnosis of localized acceleration flow.Methods We examined blood flow in the left anterior descendingcoronary arteries in 75 patients (46 patients with luminal diameter stenosis ≥ 60% in the left anterior descending coronary arteries by coronary angiography and 29 without or <60% stenosis) by transthoracic color Doppler echocardiograph and recorded multipoint pulse Doppler spectrums in the same segment. We measured the blood flow Doppler parameters and then calculated the ratio of the maximal peak diastolic velocity to the minimal peak diastolic velocity. The ratio≥1.5 was the cutoff value for the presence of localized acceleration flow. In addition, we defined retrograde LAD flow as a direction from the apex to the base of the left ventricle in the anterior groove area, and retrograde septal branch flow as a direction from posterior to anterior in the anterior interventricular septum. We regarded either the localized acceleration flow or the retrograde flow as the criteria to diagnose the left anterior descending coronary artery stenosis. Coronary angiography was performed in all patients subsequently. The value of localized acceleration flow and retrograde flow detected by transthoracic color Doppler echocardiography in the diagnosis of LAD (Left Anterior Descending Coronary Artery) stenosis was evaluated by specificity, sensitivity, positive predictive value and the negative predictive value. The value of the haemodynamic parameters in the diagnosis of localized acceleration flow was assessed by ROC curves respectively.Results 1. The ratio of the maximal peak diastolic velocity to theminimal peak diastolic velocity was significant higher in the patients with left anterior descending coronary artery stenosis than that in those without stenosis (2.07 ± 0.47 Vs 1.32 ± 0.23, P<0.01). The specificity and the sensitivity by using the ratio≥1.5 for stenosis detection were 89.7% ( 26/29) and 82.6% (38/46) respectively. The positive predictive value and the negative predictive value were 92.7%( 38/41)and 76.5%( 26/34) respectively.2. Retrograde flow could be detected in patients with severe stenotic or totally occluded left anterior descending coronary artery. The specificity and the sensitivity by using the retrograde flow for stenosis detection were 100%( 29/29)and 21.7%( 10/46), respectively. The positive predictive value and the negative predictive value werel00% (10/10) and 44.6% (29/65) respectively.3. The specificity and the sensitivity by using the localized acceleration flow together with the retrograde flow for stenosis detection were 89.7% ( 26/29) and 100% ( 46/46) respectively. The positive predictive value and the negative predictive value were 93.9% (46/49) and 100% (26/26) respectively.4. The haemodynamic parameters at stenotic site were significantly different from those at pre-stenotic site and in control group. The area under the ROC curves of relative parameters for local acceleration flow detection ranged from 0.882 to 0.983.Conclusions 1. The resting abnormal haemodynamics in stenotic left anterior descending coronary artery (luminal diameter stenosis ≥60%) was characterized by an increased ratio (≥1.5) of the stenotic velocity to the pre-stenotic velocity which was the mark of localized acceleration flow. It was important in the diagnosis of the stenotic left anterior descending coronary artery. Retrograde flow could be detected in patients with severe stenoticor totally occluded left anterior descending coronary artery. The specificity of retrograde flow for stenosis detection was 100%. The sensitivity and the negative predictive value for stenosis detection were improved significantly by using the localized acceleration flow together with the retrograde flow.2. The haemodynamic parameters at stenotic site were significantly different from those at pre-stenotic site and in control group. Some haemodynamic parameters could be used to diagnose the localized acceleration flow.In conclusion, transthoracic color Doppler echocardiography is a reliable noninvasive method to detect left anterior descending coronary artery stenosis (≥60%). It is a significant complement to coronary artery angiography.PART II . Clinical Study of Local Coronary Flow Dynamic Changes Evaluated by Transthoracic Coronary Color Doppler Echocardiography Before and After the Left Anterior Descending Coronary Artery Stent ImplantationObjective To explore the value of transthoracic coronary color Doppler echocardiography in the detection of coronary haemodynamic changes before and after rescue coronary stenting for the noninvasive assessment of the efficacy of percutaneous coronary intervention. Methods Data from 18 patients who received a coronary intervention in the left anterior descending coronary artery were analyzed. All parameters were obtained both before and after stent implantation and compared with that of 29 angiographycally normal patients.Results 18 patients had luminal stenosis (60%～100%) in the left anterior descending coronary arteries on coronary angiography and received successful stent implantation (residual stenosis <30%). Before stent implantation, these patients were found to have localized acceleration flow or retrograde flow by echocardiography and a lower ratio of the diastolic velocity to systolic velocity in the distal segment. Then the abnormal phenomenon disappeared after stent implantation, and the parameters had not significant difference compared with that of control group.Conclusions Transthoracic coronary color Dopplerechocardiography was a noninvasive method to evaluate the efficacy of percutaneous coronary intervention.