Left ventricular diastolic function in the normal and diseased heart: Perspectives for the anesthesiologist (second of two parts)
Several important questions remain to be answered by future research. First, it is unclear whether any abnormal index of diastolic function can be used to estimate disease severity, or to prognostically identify patients who will subsequently develop systolic abnormalities or frank left ventricular dysfunction. A temporal relationship between the appearance of diastolic dysfunction and ultimate left ventricular decompensation may, theoretically, exist, but such a relationship has yet to be established. Second, a growing body of evidence indicates that pharmacologic therapy with Ca2+ channel antagonists, β-adrenergic agonists or antagonists, phosphodiesterase inhibitors, or angiotensin converting enzyme inhibitors may acutely or chronically benefit certain patients with diastolic dysfunction. Whether the impact of early recognition and therapeutic intervention in patients with diastolic dysfunction can be translated into an improvement of quality of life or enhanced survival remains unknown. Third, recent evidence indicates that fundamental changes in the biochemistry of the cardiac myocyte may represent a final common pathway for the development of congestive heart failure resulting from intrinsic cardiac disease. Altered expression of genes coding for the ATP-dependent Ca2+ pumps in the sarcolemma and the sarcoplasmic reticulum, regulatory proteins such as phospholamban, and the proteins composing the contractile apparatus have been identified that play critical roles in the pathophysiology of myocardial failure, and have important implications for potential pharmacologic therapy. Future research will more clearly elucidate these cellular and biochemical mechanisms of left ventricular failure. Lastly, although intravenous and inhalational anesthetics produce derangements in normal diastolic function to varying degrees, whether the effects of these agents on diastolic performance are exacerbated in disease processes manifested by abnormal diastolic mechanics requires further evaluation.