[Measurement of regional and global coronary sinus blood flow with the continuous thermodilution technique. I. Method and experimental studies (author's transl)].

Experiences from 233 coronary sinus blood flow measurements with the Ganz continuous thermodilution technique are reported. Experimental studies revealed: 1. Because of incomplete isolation of the external thermistor against injectate one has to take into account a systematic error in the range of 3--4%. 2. If flow exceeds 200 ml/min, injection rate must be increased from 30--40 ml/min to 60--70 ml/min for complete mixing of blood and injectate. Then flow rates up to 450 ml/min may be measured precisely. 3. Using the double thermistor catheter experimental studies indicated complete mixing of blood and injectate between injection orifice and first external thermistor. 4. To avoid right atrial admixture the external thermistor should be positioned 3 cm deep into the coronary sinus. 5. It is easier to obtain an identical catheter position within the great cardiac vein, when repeated measurements at different days are necessary. Compared with other measuring methods of myocardial blood flow this technique is inexpensive and simple. It permits rapid changes in coronary sinus blood flow to be studied. The possibility to determine simultaneously myocardial substrate utilisation is of great advantage.