LITERATURE REVIEW 491

reaction mediated by C reactive protein, which is increased in myocardial ischemia, activates complement, probably through the classical pathway. Oxygenators also increase complement by direct activation of the classical pathway. Thromboxane from the lung and pulmonary artery mediates the pulmonary vascular response to complement.

The authors suggest prevention of NCPE by steroids to prevent granulocyte aggregation, superoxide production by leukocytes, and endothelial cell damage; pretreatment with aspirin, indomethacin or other drugs that block pulmonary vascular response to activated complement; administration of diphenhydramine to high-risk patients; and transfusion of packed cells to avoid leukocyte reactions. However, the efficacy of these interventions has been documented in exper- imental animal models or other similar pathophysiologic conditions (ie, shock lung), but they require further investiga- tion in NCPE.

Sade RM, Fyfe D, Alpert CC: Hypoplastic left heart syndrome: A simplified palliative opera- tion. Ann Thorac Surg 43:309-312, 1987

Since a reliable method for palliation of hypoplastic left heart syndrome is not presently available, the authors report a simplified procedure to provide adequate systemic circulation and pulmonary blood flow. Unlike the Norwood procedure, this method permits performance with a short period of circulatory arrest, minimizes interference with coronary blood flow, and has better growth potential. Specifi- cally, the technical details include wide excision of the ductus arteriosus, anastomosis of the branch pulmonary arteries to each other with a 2.5- to 3-turn opening into the main pulmonary artery, and wide anastomosis of the pulmonary artery to the hypoplastic aorta. Disadvantages include poten- tial contraction of the aorta to pulmonary artery anastomosis producing obstruction, or excessive growth of the shunt, producing congestive heart failure. Despite the attractiveness of the procedure, none of their three patients survived beyond 7 months of age.

Baxter AD, Jennings FO, Harris RS, et al: Continuous intercostal blockade after cardiac surgery. Br J Anaesth 59:162-166, 1987

The efficacy of bilateral continuous catheter intercos- tal block was compared to intravenous morphine, 2 to 5 mg, as necessary in 40 patients after median sternotomy. Bupiva- caine, 0.25%, 20 mL, was administered through each cathe- ter every six hours as necessary for 36 hours postoperatively. Measurements of forced vital capacity, inspiratory force, alveolar-arterial oxygen gradient, and lung area were assessed 30 minutes after analgesic administration. The subjective quality of analgesia, presence of pulmonary com- plications, and needs for additional analgesia were also noted. Although patients with continuous intercostal analgesia required less opioids and had lower subjective pain scores, the pulmonary function studies, gas exchange, lung volumes, and pulmonary complications were similar in both groups. Because this technique has the potential for pneumothorax, infection, and local anesthetic toxicity, its routine use cannot be justified.

Sen S, Petscher C, Ratliff N: A factor that initiates myocardial hypertrophy in hypertension. Hypertension 9:261-267, 1987

Factors other than blood pressure itself may be responsible for the myocardial hypertrophy associated with hypertension. Antihypertensive drugs such as hydralazine, which decrease arterial pressure, do not always reverse myocardial hypertrophy. A soluble factor in the hypertro- phied myocardium of spontaneously hypertensive rats stimu- lated protein synthesis by 70% and increased the specific activity of transfer RNA and rate of protein synthesis in isolated cardiac myocytes. Such a factor may be the control- ling key for the development or reversal of cardiac hypertro- phy in hypertension.

Bishop N, Adlakha HL, Boyle RM, et al: The ST segment/heart rate relationship as an index of myocardial ischemia, lnt J Cardiol 1 4 : 2 8 1 - 2 9 3 , 1987

The use of the maximal ST/heart rate slope as an index of myocardial ischernia was initially reported in 1970. Both its accuracy and disadvantages have been documented over the ensuing years. The slope is sensitive to cardiac lesions associated with myocardial ischemia such as reduced ventric- ular function and ejection fraction after myocardial infarc- tion. Valvular heart disease also affects the results with overestimation of ischemia in one patient with mitral regurgi- tation and false indication of ischemia in patients with aortic valve disease. False indication of ischemia also occurred in a patient with right bundle branch block when the slope was obtained in lead V 1. Thus the slope is sensitive to cardiac lesions associated with myocardial ischernia. Previous reports demonstrating disagreement with the use of the maximal ST/heart rate slope to detect ischernia differ from the original methods by failure to assess reproducibility or dif- ferent interpretations of results. In summary, the slope has the disadvantage of requiring laborious training and deriva- tion while suffering from the limitations of other exercise ECG evaluations.

Leppo J, Plaja J, Gionet M, et ai: Noninva- sive evaluation of cardiac risk before elective vascular surgery. J Am Coil Cardioi 9:269-276, 1987

This study reevaluates many of the risk factors incor- porated into the Cardiac Risk Index Score of Goldman et al (N Engl J Mid 297:845-850, 1977). However, the findings are substantially different because the study is prospective and includes the use of thallium scintigraphy as a screening test for coronary artery disease. Based on the results of exercise tests, thallium scintigraphy, and clinical evaluation, 11 patients received coronary angiography. Four of these patients died, two after cardiac catheterization, one after vascular surgery without cardiac surgery, and one after coronary bypass operation. In the remaining 89 patients undergoing peripheral vascular surgery, there were 15 patients with postoperative myocardial infarction (17%),

492 CAROLL. LAKE

with one fatality. Of these 15 patients, 14 demonstrated thallium redistribution and three had ST-T changes sugges- tive of ischemia during exercise testing. An abnormal thal- lium scan or thallium redistribution occurred in 47% and 38% of patients without and in 93% of patients with perioperative ischemic events. Of the former patients, there was a low-risk group characterized by absence of thallium redistribution and a persistent defect as well as an intermediate group having thallium redistribution of lesser magnitude than high- risk group, but a negative exercise test. Other preoperative factors that failed to indicate the likelihood of an ischemic event were rate-pressure product, diabetes, history of heart failure, history of angina, and total exercise time.

Although the authors state that patients with less severe degrees of thallium redistribution, good exercise toler- ance, and no other risk factors could be subjected to surgery when appropriate cardiac monitoring is used perioperatively, they did not evaluate specifically the use of hemodynamic monitoring nor the occurrence of intraoperative events such as hypertension or tachycardia, which might predispose to infarction in their series.

Wead WB, Cassidy SS, Coast JR, et al: Reflex cardiorespiratory responses to pulmonary vascular congestion. J Appl Physiol 6 2 : 8 7 0 - 8 7 9 ,

1987

In a canine preparation with an isolated left lung, pulmonary hypertension to increase pulmonary transcapil- lary pressure to 30 mmHg did not change heart rate, systemic arterial pressure, or inspiratory muscle activity. Thus, it appears that pulmonary vascular congestion does not stimu- late pulmonary C fibers sufficiently to evoke systemic hemo- dynamic or central inspiratory changes. Although the experi- mental preparation permitted examination of the reflex cardiovascular and central inspiratory responses caused solely by stimulation of the isolated left lung with expansion to 30 cm water, vascular congestion, or stimulation of nerve endings, the possibility of interruption of nerve pathways, nonperfusion of the left lung, and the absence of the normal variation of alveolar carbon dioxide tension may affect the findings.

Lundy EF, Kuhm JE, Kwon JM, et al: Infusion of five percent dextrose increases mor- tality and morbidity following six minutes of cardiac arrest in resuscitated dogs. J Crit Care 2 :4 -14 , 1 9 8 7

This study and the accompanying editorial by Yatsu, McKenzie, and Lockwood confirm previous observations on the deleterious effects of glucose administration during hypoxic/ischemic cerebral insults. In a canine model anes- thetized with halothane and subjected to 6 minutes of ventric- ular fibrillation followed by open chest cardiac massage, dogs receiving lactated Ringer's infusions had minimal deficits compared with those receiving dextrose 5% in lactated Rin- ger's (LR) solution. Animals receiving LR were extubated within three hours of arrest and required less epinephrine for maintenance of an adequate hemodynamic state, Although hyperglycemia itself does not produce cerebral damage,

augmented damage results from anaerobic glycolytic metab- olism to lactate.

Okuda H, Nakanishi T, Nakazawa M, et al: Effect of isoproterenol on myocardial mechanical function and cyclic AMP content in the fetal rabbit. J M o l Cel l C a r d i o l 1 9 : 1 5 1 - 1 5 7 , 1 9 8 7

The effects of isoproterenol, which activates beta- adrenergic receptors, and the adenylate cyclase system were studied in an isolated rabbit heart system to determine the differences in mechanical effects in fetuses and newborns. As reported by others, the effects of isoproterenol were less in the fetal than in the newborn rabbit hearts. Although the myo- cardial cyclic adenosine monophosphate (AMP) concentra- tions after isoproterenol were greater in the fetus, the inotropic effects of dibutyryl cyclic AMP were less than in the newborn. Since it appears from this study that the process from beta receptor to cyclic AMP in fetal rabbits is equal or more responsive to isoproterenol than in newborns, the decreased inotropic response may result from age-related differences in the inotropic effects of calcium.

McPherson DD, Hiratzka LF, Lamberth WC, Brandt B, Hunt M, Marcus ML, Kerber RE: Delineation of the extent of coronary atheroscle- rosis by high-frequency epicardial echocardi- ography. N E n g l J M e d 3 1 6 : 3 0 4 - 3 0 9 , 1987

Coronary angiography may underestimate the se- verity and extent of coronary disease. Using high-frequency epicardial echocardiography, the ratio of coronary arterial lumen to wall thickness was determined in 37 patients with normal coronary arteries or with atherosclerotic disease. The ratio in angiographically normal segments was less than normal in patients with documented coronary disease although there was considerable overlap with values in patients with angiographic disease at the site of evaluation. A statistically significant decrease from normal in the ratio occurred with angiographie disease at the site of evaluation. Thus, diffuse coronary atherosclerosis is often present in the angiographicaUy normal vessels of patients with discrete coronary stenoses. Because of the variability of coronary lesions (ranging from discrete protruding intraluminal lesions to diffusely thickened walls), the use of angiographically estimated percent stenosis frequently does not correlate with physiologic coronary obstruction.

Joob AW, Dunn C, M i l l e r E D , e t a h Effect of left atrial to left femoral artery bypass and renin-angiotensin system blockade on renal blood flow and function during and after thoracic aortic occlusion. J Vasc Surg 5 : 3 2 9 - 3 5 , 1 9 8 7

The effects of a bolus dose (100/~g/kg) of enalaprilat (MK 422) were compared to left atrial to left femoral bypass and simple aortic clamping in 22 dogs. Enalaprilat, a convert- ing enzyme inhibitor, was given at the time of aortic clamp- ing. During aortic occlusion, urine output, renal blood flow, and glomerular filtration rate were zero in animals subjected to either unmodified aortic clamping or administration of