Howard P. Gutgesell

Recommendations for quantitation of the left ventricle by two-dimensional echocardiography. American Society of Echocardiography Committee on Standards, Subcommittee on Quantitation of Two-Dimensional Echocardiograms.

We have presented recommendations for the optimum acquisition of quantitative two-dimensional data in the current echocardiographic environment. It is likely that advances in imaging may enhance or supplement these approaches. For example, three-dimensional reconstruction methods may greatly augment the accuracy of volume determination if they become more efficient. The development of three-dimensional methods will depend in turn on vastly improved transthoracic resolution similar to that now obtainable by transesophageal echocardiography. Better resolution will also make the use of more direct methods of measuring myocardial mass practical. For example, if the epicardium were well resolved in the long-axis apical views, the myocardial shell volume could be measured directly by the biplane method of discs rather than extrapolating myocardial thickness from a single short-axis view. At present, it is our opinion that current technology justifies the clinical use of the quantitative two-dimensional methods described in this article. When technically feasible, and if resources permit, we recommend the routine reporting of left ventricular ejection fraction, diastolic volume, mass, and wall motion score.

Usefulness of adenosine for arrhythmias in infants and children

Adenosine was administered to 25 infants and children (11 patients after presenting with a sustained arrhythmia, and 14 during a diagnostic electrophysiologic study) to determine its electrophysiologic effects. Adenosine was given as an intravenous bolus (starting dose 37.5 micrograms/kg, and increased by 37.5 micrograms/kg increments until an effect was seen). Adenosine caused tachycardia termination or transient increased atrioventricular (AV) block in all 25 patients. Seven patients had tachycardia requiring only the atria for perpetuation and developed increased AV nodal block (minimum effective adenosine dose range 37.5 to 350 micrograms/kg, mean 131). Thirteen had AV reciprocating tachycardia or AV node reentry tachycardia (minimum effective adenosine dose range 37.5 to 225 micrograms/kg, mean 114). Four other patients received adenosine to rule out preexcitation (minimum effective adenosine dose range 37.5 to 375 micrograms/kg, mean 165). One of the 25 patients had junctional ectopic tachycardia and adenosine administration caused retrograde AV block. Six of the 25 (24%) had noticeable but minor side effects. One patient had sustained bradycardia (2 to 3 minutes requiring temporary pacing). Adenosine is a safe and effective agent in the evaluation and treatment of infants and children with arrhythmias.

Noninvasive assessment of myocardial contractility, preload, and afterload in healthy newborn infants.

Assessment of ventricular contractility in the newborn infant using standard echocardiographic indexes can result in error due to the unique physiologic state that exists in the neonatal period. It has been suggested from animal and human studies that maturational alterations in contractility occur with birth and continue throughout infancy. To further investigate these developmental changes, 41 newborn infants aged 3 to 10 days and 37 children aged 3 to 18 years were evaluated with 2-dimensional and M-mode echocardiography. The rate-corrected velocity of circumferential fiber shortening (VCFc)-end-systolic wall stress (ESWS) relation was used as a load-independent estimate of contractility. Preload, afterload, and ventricular mass were also measured. Despite similar shortening fractions, the infant group had significantly higher mean VCFc and lower ESWS than the older age group (1.28 vs 1.08 circ/s and 30.2 vs 37.3 gm/m2, respectively). An inverse linear relation between VCFc and ESWS was found in both age groups. The y-intercept was higher in the infant group (p < 0.01), and the slope of the mean regression line was steeper than in the older children (p < 0.01). Ventricular mass in relation to body surface area increased with age. We conclude that (1) newborn infants have a higher basal contractile state that cannot be accounted for by lower afterload, (2) myocardial performance is more sensitive to afterload in the immature heart, and (3) shortening fraction may underestimate ventricular function in the newborn.

Management of hypoplastic left heart syndrome in a Consortium of University Hospitals

To determine current management of hypoplastic left heart syndrome, we utilized the discharge database of the University Hospital Consortium and obtained data on the surgical procedures, length of stay, hospital charges, and outcome for 636 neonates with this condition admitted to 40 member institutions from 1989 to 1993. Of the 636 patients, 95 (15%) were discharged without surgical intervention. A Norwood operation was performed in 222 (53% mortality) and transplantation in 40 (42% mortality). Median length of stay and hospital charges were 17 days and

Cardiovascular Monitoring of Children and Adolescents Receiving Psychotropic Drugs: A Statement for Healthcare Professionals From the Committee on Congenital Cardiac Defects, Council on Cardiovascular Disease in the Young, American Heart Association

57,418 for the Norwood procedure and 47 days and

Use of mean arterial pressure for noninvasive determination of left ventricular end-systolic wall stress in infants and children

126,695 for transplantation.

Incidence and risk of reintervention after coarctation repair

Reports of sudden deaths of children and adolescents treated with psychotropic medications have raised concerns regarding the appropriateness of this therapy, as well as the advisability of baseline and periodic electrocardiographic (ECG) monitoring of such patients.1 2 3 4 What follows is a review of the drug effects on the ECG, cardiovascular effects of the commonly used psychotropic medications in children and adolescents, a summary of potentially dangerous drug interactions, and recommendations for cardiovascular monitoring. Although medications can potentially cause sudden, unexpected death by a variety of mechanisms (eg, seizures, central nervous system depression, or coronary artery spasm), cardiac arrhythmias are the most frequent cause. In particular, a unique form of ventricular tachycardia termed torsade de pointes has been recognized as the arrhythmia responsible for the so-called proarrhythmic effect of several antiarrhythmia drugs, and recent evidence has pointed to a similar mechanism in syncope and deaths related to other medications5 and in the familial long-QT syndromes.6 The common feature of these conditions is delayed repolarization of the myocardium (related to abnormal sodium or potassium currents) with resultant prolongation of the QT interval of the ECG. This appears to leave the myocardium vulnerable to ventricular tachycardia, primarily in the setting of bradycardia but occasionally in association with exercise. Other ECG abnormalities, such as sinus node depression, …

Myocardial contrast echocardiography and the transmural distribution of flow: A critical appraisal during myocardial ischemia not associated with infarction

Abstract We conclude that mean arterial pressure is a reliable estimate of end-systolic pressure and can be used to simplify the determination of the stress-velocity relation.

Pediatric circulatory support systems.

We examined the need for intervention after coarctation repair in a retrospective study of 197 procedures performed between 1967 and 1989. Reintervention was required in 23 patients. No technique of coarctation repair was free from complications. Although there were only two stenoses in the group receiving Dacron patch angioplasty, only seven of these procedures were performed in children under the age of 1 year. The risk of stenosis was inversely correlated to the age at primary repair, with children less than 1 year old being at greater risk than those more than 1 year of age (p less than 0.05). Subclavian flap angioplasty had a lower risk of reoperation than end-to-end anastomosis (p less than 0.02). Formation of true aneurysms was confined to the Dacron patch angioplasty group. The morbidity and mortality for reintervention was low in all groups, with only one procedure-related death and no incidence of paraplegia. Although no technique is free from risk, subclavian flap angioplasty leads to fewer reinterventions in younger patients.

Aortic aneurysm after patch angioplasty for aortic isthmic coarctation in childhood.

OBJECTIVES This study was undertaken to determine whether myocardial contrast echocardiography can be used to estimate the transmural distribution of flow. BACKGROUND Myocardial contrast echocardiography has been shown to reliably measure average transmural blood flow during myocardial ischemia. However, there is controversy regarding its ability to determine the transmural distribution of flow. METHODS The transmural distribution of flow was measured in 21 open chest anesthetized dogs with use of radiolabeled microspheres and sonicated albumin microbubbles (mean size 4.5 microns). In the 11 Group I dogs, myocardial contrast echocardiography was performed at baseline and during left anterior descending artery stenosis. In five of these dogs, it was also performed during left circumflex artery stenosis. In these dogs large (mean 12 microns) hand-agitated bubbles were also used. In the five Group II dogs, myocardial contrast echocardiography was performed before and 45 s after intracoronary injection of 6 mg of papaverine in the presence of a critical left circumflex artery stenosis. The five Group III dogs were studied during cardiopulmonary bypass at baseline and during left anterior descending artery stenosis. Off-line image analysis of the echocardiographic images was performed and time-intensity curves obtained from these images were correlated with radiolabeled microsphere-derived flows. RESULTS The ratios of the parameters derived from the endocardium and epicardium during myocardial contrast echocardiography were found to correlate poorly (ranging from R2 = 0 to R2 = 0.35) with radiolabeled microsphere-derived endocardial/epicardial flow ratios over a wide range of flow ratios (0.01 to 2.58). These results were not influenced either by the location of the regions of interest (left anterior descending vs. left circumflex artery bed) or by the size of the bubbles (4.5 vs. 12 microns). CONCLUSIONS Myocardial contrast echocardiography cannot be used to assess the transmural distribution of flow during myocardial ischemia not associated with infarction.