Annotated ECGStatus Report to RCRIM 1/20/2014

Given by: Barry Brown

Continuous ECGs for FDAFDA wants to receive annotated

ECG waveforms from continuous ECG recordings collected in clinical trials

FDA commissioned Mortara to augment the ECG Warehouse to support receipt, analysis, and display of continuous ECGs

Too Much Data for XMLContinuous ECGs contain too

much data for XMLWorst case for FDA requirements

would require a 9 GB aECG XML file

Everyone agrees that the waveform data must be left in binary files

Mortara added minimal (but proprietary) changes to HL7 aECG to support use of external files for ECG Warehouse project

Dec. 2013 Workshop in D.C.Mortara, AMPS, and FDA hosted a

workshop for pharmaceutical industry about submitting continuous data to ECG Warehouse

The proprietary aECG changes were discussed so industry could start submitting data to ECG Warehouse while HL7 works through the standardization process

How to Standardize in HL7?Barry Brown worked with Gunther

Schadow and Mead Walker to propose minimal changes to HL7 while meeting the needs of FDA

Most changes can be handled in a supplemental Implementation Guide for aECG

However, we also need to make a small change to the SLIST data type

SLISTSLIST is for “sampled” lists, like

ECG waveformsToday, the“digits” of SLIST are

listed directly in the aECG XML

SLIST.digits >> EDWe just need to allow for

encapsulation of the SLIST digitsLet’s use ED-like attributes to

describe the location of digits in an external binary file

XML for ED<!-- type ED --><x nullFlavor = ( NI | INV | OTH | NINF | PINF | UNC |

DER | UNK | ASKU | NAV | QS | NASK | TRC | MSK | NA ) flavorId = ST* updateMode = (A | D | R | AR | N | U | K) representation = (B64 | TXT) : TXT language = CS mediaType = CS compression = CS integrityCheck = BIN description = ST integrityCheckAlgorithm = (SHA-1 | SHA-256) : SHA-1> Content: ( reference, thumbnail, translation*,

(#PCDATA | any) )</x>

Need More Attributes

6 -16 37 120

23 -45 49 147

37 -29 68 158

-5 -14 87 75

headerSize

recordSize

itemOffsetIntoRecord

I II III V6

itemSize

ECG waveform leads are normally interleaved (or multiplexed) in a binary file.

Need to describe location of each lead separately.

SLIST.digits Attributes<digits> Attribute DefinitionmediaType (CS) MIME of referenced file. Same as ED.

application/octet-stream = binary file.compression (CS) Compression. Same as ED. Defaults to no compression.

DF = deflate, GZ = gzip, ZL = zlib, Z = compress

itemByteOrder* (CS) The format of the integer values. Defaults to LE.

LE = little endian binary integers; least significant byte first and then in the order of ascending significance.

BE = big endian binary integers; most significant byte first and then in the order of descending significance.

itemType* (CS) Data type of the item. No default.

INT = signed integer (2’s compliment) UINT = unsigned integer

itemSize* (INT) 1, 2, 4, or 8 bytes. No default.headerSize* (INT) The number of bytes to skip over to get to the first record. Defaults to 0.recordSize* (INT) The number of bytes per record. No default.itemOffsetIntoRecord* (INT) The byte offset of the item within the record. No default.recordCount* (INT) Number of records to read from the file. Defaults to reading to the end

of the file.

* Not from ED

SLIST.digits in Binary File

Beat-by-Beat AnnotationsContinuous ECGs are often

analyzed with signal processing algorithms

Sponsors and labs may want to submit beat-by-beat annotations with the continuous waveforms

The beat-by-beat annotations should also be encoded in external binary files

Beat-by-Beat Annotations

MDC Beat Types

Beat Types in Binary File

QRST Onset in Binary File