Comparative Effects of Left Atrial or Left Ventricular Bypass on Coronary Sinus Flow and Oxygen Usage in Dogs

Abstract

Comparative coronary sinus flow rates and oxygen AV difference were studied in dogs undergoing left heart bypass with left atrial or left ventricular drainage at similar maximum obtainable flow rates. Left atrial bypass decreased the coronary sinus flow rates and oxygen consumption when compared with control values. These values were further decreased when left ventricular bypass was used. The oxygen consumption data were highly significant and give further evidence of increased effectiveness of complete bypass of the left ventricle in myocardial support systems.L EFT HEART BYPASS has been used both experimentallyl'7'10,13,14.17.l8 and clinically2'6'8'9'21 as a method of myocardial support. Although both the left atrial and left ventricular chambers have each been used as sites for decompression of the left side of the heart, the relative effectiveness of these two approaches in reducing myocardial oxygen consumption has not been clarified.20 The purpose of this study was to determine the comparative effectiveness of each site of drainage in reducing myocardial oxygen consumption during left heart bypass at comparable flow rates. MethodFourteen healthy mongrel dogs weighing 18 to 25 kg were used. Materials having contact with the blood were sterile; however, the experiments were conducted under clean rather than sterile conditions. Intermittent pentothal sodium was used intravenously for narcosis and oxygen was delivered by a positive-pressure ventilator. Animals were heparinized with 300 units/kg of aqueous heparin sodium (1000 units/ml).The right carotid artery was exposed and a #8 cardiac catheter inserted retrogradely into the left ventricular

Evaluation of mechanical left ventricular assistance with left atrium to aorta bypass in dogs.

“…Sato and Glenn (1970), Schenk et al (1964) and Wakabayashi et al (1975) reported no significant change in either CBF or MVO2 during LHB. Tamura reported a slight increase of CBF and significant reduction of MVO2, but on the contrary, Dennis et al (1963) and Miller (1974) described a decrease of CBF by 30 to 40% and observed a significant reduction of MVO2. In our study, both CBF and MVO2 decreased significantly during LA-AO LHB.…”

“…Some investigators observed reduced TTI by LA-AO LHB (Nitta et al 1973), but Miller et al (1974) showed no decrease of TTI while MVO2 substantially decreased. With properly driven LV-AO LHB, the left ventricle is nearly completely decompressed, and thus, the TTI decreases by 70% of the control reportedly (Hughes et al 1975;Watanabe et al 1975).…”

Critical Analysis of Intra-aortic Balloon Counterpulsation and Transapical Left Ventricular Bypass in the Sufficient and Insufficient Circulation

“…The hemodynamic effectiveness of counterpulsation and bypass have been demonstrated in animal. experiments (10,16,25,29,35,41,52,53,54,57,58,62,67,70,71,74) and in clinical use (2,17,30,31,38,55,56,66,73,78). Furthermore, in experiments an dogs, mechanical assist of the circulation has been reported to be effective an ischemic myocardium, a reduction of up to 50% of experimentally induced myocardial infarction being accomplished by counterpulsation (60,70,71) and left heart bypass (25,35,52).…”

Αιμοδυναμικές Μεταβολές Της Κυκλοφορίας Κατά Τη Μηχανική Υποβοήθηση Της Ανεπαρκούσης Αριστερής Κοιλίας Με Ενδαορτική Αντλία Αντιώθησης Ή Φυγόκεντρο Αντλία

“…Α) Συσκευές μηχανικής υποβοήθησης συνδεδεμένες παράλληλα με την καρδιά 22,23 Διακρίνονται σε συσκευές που προορίζονται για: 27 . Αντιθέτως σε μελέτες 31,32 που χρησιμοποιήθηκε αντλία roller που συνδέονταν παράλληλα με την καρδιά, παρατηρήθηκε σημαντική μείωση της κατανάλωσης Ο 2 μόνο όταν γίνονταν ολική παράκαμψη της αριστερής κοιλίας (100% bypass). Κάποιοι ερευνητές απέδωσαν τα διαφορετικά αυτά αποτελέσματα στο διαφορετικό τρόπο λειτουργίας της Φυγοκέντρου και της αντλίας roller.…”

“…Ο Miller και συν. 32 , διαπίστωσε μεγαλύτερη ελάττωση της ροής στο στεφανιαίο κόλπο κατά την ολική παράκαμψη της αριστερής κοιλίας με αντλία roller συγκριτικά με τη μερική παράκαμψή της με την ίδια αντλία. θ) Καρωτιδική ροή -Εγκεφαλική ροή σε φυσιολογική καρδιά: Αντιφατικά αποτελέσματα προέκυψαν από διαφορετικές ερευνητικές ομάδες όσον αφορά την επίδραση της Φυγοκέντρου αντλίας στην καρωτιδική ροή.…”