Definition for heart valve replacement service request

{
  "resourceType" : "ActivityDefinition",
  "id" : "heart-valve-replacement",
  "extension" : [{
    "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-wg",
    "valueCode" : "cds"
  }],
  "status" : "draft",
  "publisher" : "HL7 International / Clinical Decision Support",
  "contact" : [{
    "telecom" : [{
      "system" : "url",
      "value" : "http://www.hl7.org/Special/committees/dss"
    }]
  }],
  "description" : "Heart valve replacement",
  "useContext" : [{
    "code" : {
      "system" : "http://terminology.hl7.org/CodeSystem/usage-context-type",
      "code" : "age"
    },
    "valueCodeableConcept" : {
      "coding" : [{
        "system" : "https://meshb.nlm.nih.gov",
        "code" : "D000328",
        "display" : "Adult"
      }]
    }
  },
  {
    "code" : {
      "system" : "http://terminology.hl7.org/CodeSystem/usage-context-type",
      "code" : "user"
    },
    "valueCodeableConcept" : {
      "coding" : [{
        "system" : "http://snomed.info/sct",
        "code" : "309343006",
        "display" : "Physician"
      }]
    }
  }],
  "purpose" : "Describes the proposal to perform a Heart Valve replacement.",
  "usage" : "This activity definition is used as the definition of a service request to perform a heart valve replacement. Elements that apply universally are defined here, while elements that apply to the specific setting of a referral within a particular order set are defined in the order set.",
  "topic" : [{
    "coding" : [{
      "system" : "http://snomed.info/sct",
      "code" : "34068001",
      "display" : "Heart valve replacement"
    }]
  }],
  "kind" : "ServiceRequest",
  "code" : {
    "coding" : [{
      "system" : "http://snomed.info/sct",
      "code" : "34068001",
      "display" : "Heart valve replacement"
    }]
  },
  "timingTiming" : {
    "_event" : [{
      "extension" : [{
        "url" : "http://hl7.org/fhir/StructureDefinition/cqf-expression",
        "valueExpression" : {
          "language" : "text/cql",

          "language" : "text/cql-expression",

          "expression" : "Now()"
        }
      }]
    }]
  },
  "location" : {
    "reference" : {
      "reference" : "Location/1"
    }
  },
  "participant" : [{
    "type" : "practitioner",
    "role" : {
      "coding" : [{
        "system" : "http://nucc.org/provider-taxonomy",
        "code" : "207RI0011X",
        "display" : "Interventional Cardiology Physician"
      }],
      "text" : "Interventional Cardiology"
    }
  }],
  "bodySite" : [{
    "coding" : [{
      "system" : "http://snomed.info/sct",
      "code" : "17401000",
      "display" : "Heart valve structure"
    }]
  }]
}