The PhonoCardioSelectorsBoris Gramatikov

Boris Gramatikov's PhD thesis

PhonoCardioSelectors are microprocessor-based devices for automatic signal acquisition and mass-screening diagnostics of phonocardiographic signals in children in the age 3-16. The heart sounds are recorded by a microphone from the chest-wall in the precordial region (standard auscultation points), and stored in computer memory. Special algotithms were developed and software was written to detect pathological changes in the phonocardiographic signals caused by improper valve function or vicia. ECG analysis is conducted in parallel. All abnormal findings are displayed on the front panel using LEDs.

The electrocardiographic signal is monitored for rhythm, heart rate, and QRS shape. The phonocardiogram (PCG) is examined for duration of the first, second and third heart sounds, the amplitude, shape and duration of systolic and diastolic murmurs, as well as for a split second sound. The measurements are independent of the heart rate. Several heart beats are processed in order to exclude false-positive indications caused by respiration, external noise or incidental artefacts. The diagnostic accuracy was better than 95%, with false-negative diagnoses below 2%. The examination time was 2-4 minutes per child.

These devices have successfully been used at the Pediatric Clinic, Medical Academy, Sofia, Bulgaria, for screening of infants and children, and as a supplemental diagnostic utility to echocardiographic examinations.

This project was related to Boris Gramatikov's PhD thesis entitled Electronic Devices for Automatic Processing of Phonocardiographic Signals. It dealt with selection of appropriate analog filters of minimized ringing and diagnostically optimal passband, effective A/D sampling and compressed data storage (without missing diagnostically important information), and automatic "intelligent" gain control. Further, several algorithms were developed for detection of heart sounds (S1, S2 and S3), identification of pathologically altered heart-sound amplitudes, split sounds etc. Specialized procedures for detection of heart murmurs between sounds were developed. Using the location and shape of the murmurs, judgement about their origin (mitral valve, tricupsid valve, vicium) or their type (insufficiency, regurgitation etc.) was made.

During the period 1980-83 Boris Gramatikov designed and built two PhonoCardioSelectors for automatic signal acquisition and screening diagnostics of phonocardiosignals in children. The author has coded all his algorithms in Assembly language.

Publications:

Gramatikov, B. I. Phonocardiographic filters (in German). Congress'85 of the East-German Society for Biomedical Engineering and Computing. Leipzig, Germany, April 1985; In Proceedings, presentation B-32, pp. 110-111.

Gramatikov, B. I., Dotsinski, I. A.   Automatic gain conrtol of phonocardiographic signals (in German).   Congress'82 of the East-German Society for Biomedical Engineering and Computing. Dresden, Germany, March 1982 . In Abstracts., C-43, p.58.

Dotsynsky, I. A., Gramatikov, B. I., Ninova, P. P.   Microprocessor analysis of phonocardiosignals in children.   Fifth conference on Bioengineering, 20-24 Sept., 1981, Budapest. (in English), In Collected Abstracts, pp.64-65.