```xml
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ns4:query_definition xmlns:ns2="http://www.i2b2.org/xsd/cell/crc/psm/1.1/" xmlns:ns4="http://www.i2b2.org/xsd/cell/crc/psm/querydefinition/1.1/" xmlns:ns3="http://www.i2b2.org/xsd/cell/crc/psm/analysisdefinition/1.1/">
    <query_name>Opera-Opera-Remov@08:28:23</query_name>
    <query_timing>ANY</query_timing>
    <specificity_scale>0</specificity_scale>
    <panel>
        <panel_number>1</panel_number>
        <panel_timing>ANY</panel_timing>
        <panel_accuracy_scale>100</panel_accuracy_scale>
        <invert>0</invert>
        <total_item_occurrences>1</total_item_occurrences>
        <item>
            <hlevel>3</hlevel>
            <item_name>Operations on cardiovascular system</item_name>
            <item_key>\\i2b2_PROC\i2b2\Procedures\PRC\ICD9 (Inpatient)\(35-39) Operations on cardiovascular system\</item_key>
            <item_icon>FA</item_icon>
            <tooltip>Procedures \ ICD9 (Inpatient) \ Operations on cardiovascular system</tooltip>
            <class>ENC</class>
            <item_is_synonym>false</item_is_synonym>
        </item>
    </panel>
    <panel>
        <panel_number>2</panel_number>
        <panel_timing>ANY</panel_timing>
        <panel_accuracy_scale>100</panel_accuracy_scale>
        <invert>0</invert>
        <total_item_occurrences>1</total_item_occurrences>
        <item>
            <hlevel>4</hlevel>
            <item_name>Operations on vessels of heart</item_name>
            <item_key>\\i2b2_PROC\i2b2\Procedures\PRC\ICD9 (Inpatient)\(35-39) Operations on cardiovascular system\(p36) Operations on vessels of he~\</item_key>
            <item_icon>FA</item_icon>
            <tooltip>Procedures \ ICD9 (Inpatient) \ Operations on cardiovascular system \ Operations on vessels of heart</tooltip>
            <class>ENC</class>
            <item_is_synonym>false</item_is_synonym>
        </item>
    </panel>
    <panel>
        <panel_number>3</panel_number>
        <panel_timing>ANY</panel_timing>
        <panel_accuracy_scale>100</panel_accuracy_scale>
        <invert>0</invert>
        <total_item_occurrences>1</total_item_occurrences>
        <item>
            <hlevel>5</hlevel>
            <item_name>Removal of coronary artery obstruction</item_name>
            <item_key>\\i2b2_PROC\i2b2\Procedures\PRC\ICD9 (Inpatient)\(35-39) Operations on cardiovascular system\(p36) Operations on vessels of he~\(p36-0) Removal of coronary arter~\</item_key>
            <item_icon>FA</item_icon>
            <tooltip>Procedures \ ICD9 (Inpatient) \ Operations on cardiovascular system \ Operations on vessels of heart \ Removal of coronary artery obstruction</tooltip>
            <class>ENC</class>
            <item_is_synonym>false</item_is_synonym>
        </item>
    </panel>
</ns4:query_definition>

```

I want to find patients who have had operations on the cardiovascular system, specifically focusing on operations involving the removal of coronary artery obstruction, regardless of the timing or accuracy of the procedure.