Scandinavian journal of thoracic and cardiovascular surgery. Supplementum最新文献

Although necessary for the ultimate tissue survival, reperfusion may paradoxically exacerbate the ischemic injury. Ischemia and reperfusion injury is intimately woven together. The relative role of reperfusion injury is not clarified and probably varies with the ischemic insult: Reperfusion is always preceded by ischemia, and some of the reperfusion-related events may represent a process continuing from the ischemic period; thus the proper designation should be ischemia-reperfusion injury. The reperfusion-related events are: arrhythmias, myocardial stunning with both systolic and diastolic dysfunction, and low reflow and microvascular stunning. Of pathogenetic importance are the mode and speed of reperfusion as well as the initiation of an intracoronary inflammatory reaction during reperfusion, including endothelium-leukocyte interaction, platelets, generation of oxygen free radical, generation and release of arachidonic acid metabolites, platelet activating factor, endothelium derived relaxing factor, endothelins, kinins, and histamine, complement activation, disturbances in calcium homeostasis, and disturbances in lipid and fatty acid metabolism.

The present review concerns modern operative myocardial management strategies utilizing cold and warm blood cardioplegia. Both biological and surgical rationales toward providing optimal operative conditions in which to conduct complicated procedures are discussed. An alternative technique employing both cold and warm blood cardioplegia, as well as a cardioplegic formulary are proposed.

Toxic oxygen metabolites (TOM) are generated by activated leukocytes and ischemic tissue upon reperfusion, and are cardiotoxic in vitro. Generation of TOM during reperfusion in vivo has been measured directly and indirectly. TOM contribute to myocardial stunning, causing systolic and diastolic dysfunction. TOM may also play a role in the pathogenesis of reperfusion arrhythmias. It is uncertain if TOM cause cell death during reperfusion. Inhibition of TOM with antioxidants may be important for myocardial protection during cardiac surgery.

Concentric hypertrophy of the left ventricular wall is the primary consequence of acquired aortic stenosis (AS). Reduced left ventricular (systolic) function usually returns to normal after aortic valve replacement (AVR) in AS. Afterload mismatch prior to AVR, and not reduced contractility, is thought to be the explanation. Together with "the prosthetic valve disease" the afterload mismatch theory is used conceptually to postpone AVR until severe symptoms prevail. However, latent or manifest myocardial ischaemia/hypoxia is a central abnormality in concentric hypertrophy, also in the absence of coronary artery disease (CAD); impaired left ventricular diastolic function due to both reduced (active) relaxation and passive qualities of hypertrophied muscle is the primary cause of congestive failure symptoms. Reduced systolic function (ejection fraction) develops in succession, and dilation of the ventricle is an end-stage phenomenon. With the present timing of operative intervention significant late excess mortality from congestive heart failure is the rule after AVR in AS. Early functional improvement is probably related to reduced myocardial oxygen demand associated with afterload reduction caused by AVR, irrespective of irreversible myocardial disease. Employing a 22-year surgical series, multivariate predictive models were made for the following effect measures of AVR: early mortality, long term survival, prosthesis related complications, sudden heart related events, recurrence of congestive heart failure, heart pathology at autopsy, and left ventricular systolic and diastolic function 12 years after AVR. A prognostic index was calculated for each patient from variables related to pre-AVR degree of heart disease. A low prognostic index corresponding to operative intervention early in the course of AS predicted an operative mortality approaching zero, a normal sex and age specific long term survival, a normal rate of the quantitatively most important prosthesis related complications, a normal rate of heart related events, complete symptom freedom early after the operation without late return of congestive heart failure, and normal left ventricular function late after the operation. Complete regression of left ventricular hypertrophy was a dominant underlying mechanism. Imparied diastolic function of the left ventricle at late reinvestigation, being related to significant residual hypertrophy, was the sole predictor of fatal congestive heart failure irrespective of (a usually normal) ejection fraction. A policy of consistent coronary artery bypass grafting concomitant with AVR in case of CAD reduced early mortality rate in such patients, including the elderly, to the (low) level of those without CAD. A normal survival can, however, not be anticipated in AS patients with concomitant CAD.(ABSTRACT TRUNCATED AT 400 WORDS)

Topical (local) cooling of the heart is a valuable adjunct to cold cardioplegia, particularly to crystalloid cardioplegia and to cardioplegia in patients with long aortic cross-clamping times. The topical cooling not only enhances myocardial hypothermia but also prevents the heart from being rewarmed by coronary collaterals and by heat transmission from surrounding organs during the period of aortic cross-clamping. If ice slush is used for topical cooling, a cardiac insulating pad should be used to isolate the heart and to protect the left phrenic nerve from cold injury. To illustrate the use of the insulating pad and to demonstrate the efficiency of topical cooling during open-heart surgery, a series of temperature measurements were made.