The effects of left atrial and left ventricular cannulation on left ventricular function
Sethia, B.; Martin, W.; Wheatley, D.J.
International Journal of Artificial Organs 8(6): 331-334
1985
ISSN/ISBN: 0391-3988 PMID: 4077292 Document Number: 252187
A study in anesthetised dogs was undertaken to investigate the immediate effects of cannulation of the heart for left heart bypass on left ventricular function. Twenty-six mongrel dogs were studied. In the first group of 13 dogs (Group A), left atrial cannulation was performed through the atrial appendage and in the second group of 13 dogs (Group B), the left ventricular apex was also cannulated. Systemic blood pressure, heart rate, left atrial pressure, left ventricular end diastolic pressure and dP/dT showed no difference in left ventricular function between Groups A and B. Global ejection fraction (EF) measured by injection of technetium99m-labelled human serum albumin with gated left ventricular imaging, showed no significant difference between the two groups but analysis of the regional contribution to global EF in Group B dogs demonstrated a significant reduction in left ventricular function at the site of ventricular cannulation (P < 0.05). These findings, together with other reported disadvantages of left ventricular cannulation, suggest that the left atrium is the preferred site for cannulation when left heart bypass is required. Many reports attest to the value of mechanical circulatory support in patients with ventricular dysfunction who cannot be weaned from cardiopulmonary bypass. Initial support is commonly provided by an intra-aortic balloon pump but, in more severe cases, use of a left ventricular assist device may be warranted. More recently, such devices have also been employed in the management of patients with cardiogenic shock refractory to medical therapy (10). Left ventricular assistance may be provided by cannulation of the left atrium or the apex of the left ventricle with return of blood to the aorta or femoral artery. Ventricular assist using left ventricular cannulation may produce a greater reduction in left ventricular work and reduced infarct size when compared with left atrial cannulation, but placement of the apical ventricular cannula may itself damage normal myocardium. Both left ventricular and left atrial cannulation techniques have been employed successfully in clinical practice. However, the controversy over the relative merits of left ventricular and left atrial cannulation remains unresolved. We therefore decided to compare the immediate effects of left ventricular and left atrial cannulation upon left ventricular function.