LITERATURE REVIEW 265

they would cross a surgical anastomosis. Patients presenting for cardiac transplantation usually have full stomachs, both as a result of the emergency nature of the procedure and the administration immediately preoperatively of oral cyclospor- ine A.

In the posttransplantation patient, general anesthesia with narcotics has been used, although 4.4% of patients in this series received regional anesthesia for subsequent proce- dures. Early extubation of the transplant patient is performed to minimize the risk of pulmonary bacterial colonization and infection in the immunosuppressed patient. The differences in cardiovascular parameters in the transplant recipients are extensively discussed in this paper. A transplanted heart is denervated but retains intrinsic control mechanisms includ- ing the Frank-Starling effect, normal impulse formation and conductivity, and intact alpha- and beta-adrenergic recep- tors. The resting heart rate ranges from 90 to 120 beats/rain because of the absence of vagal tone. Coronary flow is increased because the coronary circulation loses basal alpha- adrenergic tone but remains responsive to alpha-adrenergic drugs. The normal response of hypotension and tachycardia in response to hypovolemia is absent. Preload manipulation, steroid coverage, and the use of directly acting drugs such as isoproterenol and phenylephrine to control the heart rate and afterload are essential in the perioperative management of the posttransplant patient.

Detsky AS, Abrams HB, Forbath N, et ah Cardiac assessment for patients undergoing non- cardiac surgery. A multifactorial clinical risk index. Arch Intern Med 146:2131-2134, 1986

Clinical use of another multifactorial cardiac risk index is reported by a group of internists in this article. Their study design, statistical analysis, and outcome of a prospec- tive study of a modification of the Goldman CRIS were previously reported in the Journal of General Internal Medi- cine, 1:211-219, 1986. Modifications include (1) inclusion of myocardial infarction more than 6 months ago, unstable angina within 3 months, and presence at any time of alveolar pulmonary edema as risk factors; (2) changes in the number of points attributed to various risk factors (valvular disease, 20; arrhythmias, 5; poor general medical status, 3; and emergency surgery, 10); and (3) calculation of a "pretest probability," the incidence of severe cardiac complications in patients undergoing specific surgical procedures in the authors' clinical practice (a general medical consultation service in a tertiary care setting). Using a nomogram pre- sented in the article, the pretest probability and the patient's score on the risk factors are converted to the patient's posttest probability of perioperative cardiac complication. The major problem with the data is the determination of the "pretest probability" since the risk of cardiac complications is likely to be affected by primary v tertiary care settings, choices of surgical procedures, the use of invasive monitoring devices, and possibly other factors.

Santamore WP, Shaffer T, Hughes D: A theoretical and experimental model of ventricular

interdependence. Basic Res Cardiol 81:529-537, 1986

A two-compartment model of the right and left ventri- cles was created to determine the interrelationships between the two ventricles. It correlated welt with a physical model and a postmortem heart preparation and could be used to predict the effect of hypertrophy, myocardial ischemia, and other conditions on ventricular interdependence. The impor- tance of the interventricular septum in the transfer of infor- mation on pressure and volume between the two ventricles was documented by the model.

Staub NC: Clinical use of lung water mea- surements. Chest 90:588-593, 1986

This article both reviews the consensus of a workshop held in 1984 on measurement of lung water and the current state of the art. Methods for the measurement of lung water include chest x-ray, positron emission, nuclear magnetic resonance imaging, soluble gas uptake, indicator dilution, microwave transmission, and Compton scatter. Of these methods, the chest radiograph remains the reference stan- dard. Only positron emission approaches it in accuracy. However, the cost of either positron emission or nuclear magnetic resonance techniques coupled with the difficulties in transfer of critically ill patients to these facilities makes these methods impractical. The usual clinical method for lung water measurement is the indicator dilution method, although it usually overestimates the water volume. The use of deuterium oxide as the indicator gives rapid results, is nonradioactive, but underestimates the lung water by 25%. Variable effects on lung water measured by the indicator dilution methods have been reported with positive end- expiratory pressure. Although lung water measurements have been made for 25 years, the technology is still complex and not easily adaptable to the critically ill patient.

Sullivan ID, Robinson P J, Wyse RKH, et al: Continuous-wave Doppler in the evaluation of simple and complex congenital heart disease in infants and children. Int J Cardiol 13:69-80, 1986

Continuous-wave Doppler assessment of outflow tract gradients in children provides accurate information in simple defects but is inaccurate in complicated defects. Underesti- mation of gradients occurs when obstruction to flow occurs at more than one level or the stenotic jet is located posteriorly in the valvular orifice. The measured gradients can be used clinically if they are large, but small gradients should be verified by invasive investigation. Continuous-wave Doppler has major practical problems when used to assess obstructive cardiac disease. The accompanying editorial by Wilson (Int J Cardiol 13:79-80, 1986) points out the difficulties of compar- ing nonsimultaneous Doppler gradients with those measured at catheterization because of (1) sedated v nonsedated patients and (2) instantaneous Doppler gradients v peak- to-peak gradients.

Smith M-L, yon Hanwehr R, Siesjo BK: Changes in extra- and intracellular pH in the

266 LITERATURE REVIEW

brain during and following ischemia in hypergly- cemia and in moderately hypoglycemic rats. J Cereb Blood Flow Metab 6:574-583, 1986

Concerns about the effects of hyperglycemia on cere- bral tissue have recently been evaluated. In rats with incom- plete forebrain ischemia for 15 minutes, hyperglycemic ani- mals (plasma glucose, 20 #mol/mL) developed more pronounced intra- and extracellular acidosis on reperfusion, with the tissue lactate content increasing to 20 ~mol/g and corresponding decreases in e×tracellular pH. In hypoglycemic animals, the tissue CO/content was essentially unchanged, and the lactate content increased from 2 to 10 #mol/g only. The acidosis resolved more slowly in the hyperglycemic ani- mals. Control of blood glucose during cerebral ischemia and reperfusion may be advantageous.

Wellens H J J, Brugada P, Stevenson WG: Programmed electrical stimulation: Its role in the management of ventricular arrhythmias in coro- nary heart disease. Prog Cardiovasc Dis 29:165- 180, 1986

Programmed electrical stimulation is still in a state of development according to this excellent review. The purpose of programmed electrical stimulation is to induce and record clinically occurring dysrhythmias. Five extracardiac leads and three intracardiac electrodes (right atrium, His bundle, and right ventricle) are minimal requirements. Different stimulation protocols are used in different institutions, and future work must be done to determine the correct protocol, compare modes of induction of dysrhythmias in-different populations using the same protocol, compare the sensitivity of different protocols, and assess the significance of induced ventricular arrhythmias in relation to their mode of induc- tion.

Polymorphic ventricular tachycardia (VT) is the most common dysrhythmia induced in patients without intrinsic cardiac disease or a history of dysrhythmias. Monomorphic VT is rarely induced in the absence of structural heart disease. During aggressive stimulation protocols ventricular fibrillation (VF) can be induced even in normal hearts, although the number of premature stimuli required a r e

usually greater in normal hearts. Nevertheless, the induction of VF is usually considered a nonspecific finding. Pro- grammed electrical stimulation is of little value in the evalua- tion of patients with short-lasting VT or syncope, but is very useful in the identification of the patient at high risk for sudden death after myocardial infarction or in the evaluation

of antiarrhythmic drug therapy in patients with spontaneous sustained monomorphic VT.

Bjurstrom RL, Schoene RB, Pierson D J: The control of ventilatory drives: Physiology and clinical implications. Respir Care 31:1128-1140, 1986

This interesting review article describes the factors involved in normal respiration and provides clearly written, up-to-date information on the various stimuli to breathing. Alterations in normal physiology associated with sleep apnea, chronic obstructive lung disease, and primary alveolar hypo- ventilation syndrome are also described. The effects of exer- cise on ventilation and the mechanism of exercise hyperpnea are discussed. Finally, the changes in ventilation in response to altitude, including the observation that high-altitude pul- monary edema occurs in humans with blunted chemosensitiv- ity to hypoxia and hypercapnia, are presented together with a suggestion that a respiratory stimulant might be efficacious in the prevention or treatment of mountain sickness.

A C K N O W L E D G M E N T

The papers reviewed for this issue included those published in the following journals: Anesthesiology, Anes- thesia and Analgesia, Anaesthesia, Cardiovascular Re- search, British Journal of Anaesthesia, Journal of Trauma, Circulation Research, Journal of Cardiovascular Pharma- cology, Circulation, British Heart Journal European Heart Journal, American Journal of Cardiology, Journal of the American College of Cardiology, Journal of Applied Physi- American College of Cardiology, Journal of Applied Physi- ology, Journal of Pharmacology and Experimental Thera- peutics, Critical Care Medicine, Journal of Thoracic and Cardiovascular Surgery, Annals of Thoracic Surgery, Blood, Transfusion, American Review of Respiratory Dis- eases, Chest, Archives of lnternal Medicine, American Heart Journal, Artificial Organs, Basic Research in Cardiology, Journal of Molecular and Cellular Cardiology, Arterioscle- rosis, Hypertension, International Journal of Cardiology, Journal of Cerebral Blood Flow and Metabolism, Lung, Progress in Cardiovascular Diseases, Respiratory Care, and Stroke.

Carol L. Lake, MD Department of Anesthesiology

University of Virginia Charlottesville