Arthur A. Klein

LONGITUDINAL STUDY OF CARDIAC FUNCTION IN THALASSEMIA MAJOR

Despite modifications in the management of /3 thalassemia major, the cardiac complications of hemochromatosis have continued to cause death in adolescence and early adulthood in patients with this disorder. From 1964 through 1977, 3 1 transfusion-dependent thalassemic patients have been followed at The New York Hospital-Cornell Medical Center until their death. In addition, 62 patients currently followed at this center have been investigated extensively prior to chelation therapy. These two patient groups form the basis of this report focusing on the natural history of cardiac disease and on cardiac function in thalassemia major.

A Five-Year Clinical Experience with 112 Blalock-Taussig Shunts

In spite of recent advances in neonatal open repair for complex cyanotic heart disease, some patients require palliation with a systemic‐to‐pulmonary artery shunt. We report a 5‐year experience (1985–1990) with 112 Blalock‐Taussig shunts. Forty‐six of the 92 patients had some variant of tetralogy of Fallot, with a wide spectrum of diagnoses in the remainder. The median age at surgery was 3 months. A classic Blalock‐Taussig shunt was done in 26% (group I), and a 4‐ or 5‐mm PTFE graft was utilized in the remainder (group II). The technical aspects of each of the procedures are reviewed. There were three early deaths in the entire group, none of them related to Blalock‐Taussig shunt function. There was no incidence of early shunt insufficiency, bleeding, infection, limb ischemia, or pulmonary artery distortion. There was a 21% incidence of clinical congestive heart failure, seen somewhat more commonly in group I. The overall need for reshunting/open repair was similar in both groups, but there was a statistically longer interval between the initial Blalock‐Taussig shunt and the second procedure in group I (21.6 vs 12.4 months). The Blalock‐Taussig shunt remains a safe, reliable, and effective means of increasing pulmonary flow. (J Card Surg 1993; 8:9–17)

Incidence and Risk Factors for Mitral Valve Prolapse in Severe Adolescent Idiopathic Scoliosis

Abstract. Mitral valve prolapse (MVP) is known to be associated with thoracic skeletal anomalies. To determine the incidence and risk factors for mitral valve prolapse in the adolescent population with severe idiopathic scoliosis (IS), a prospective follow-up study on 139 adolescent patients with IS from the Pediatric Orthopedic Service was undertaken. Data collected included age, sex, medical and family history, physical exam, electrocardiogram and echocardiogram, spinal x-rays, and pulmonary function tests. MVP was detected by echocardiogram in 13.6% (19/139) of patients with IS as compared with 3.2% in 154 age- and weight-matched controls (p < 0.006). All patients with MVP were asymptomatic and a systolic click or murmur was detected on the single preoperative exam only in 37% (7/19) of them. Patients with MVP and IS weighed less (45.1 ± 2.0 vs 51.8 ± 0.1 kg, p < 0.002) as compared with those IS patients without MVP. The electrocardiogram was abnormal in 21% (4/19) of patients with MVP as compared with only 1.6% (2/120) of patients with IS but no MVP. The two groups did not differ with respect to age at diagnosis, severity of scoliosis, positive family history of scoliosis, or the presence of restrictive lung disease. Though IS was more prevalent in females (79%), the presence of MVP was not related to gender. MVP was persistent in 10 of the 19 patients reevaluated by echocardiogram 2–4 years after spinal surgery. We conclude that MVP is four times more common in patients with severe IS than in the normal adolescent population, and is associated with a lower body weight in IS patients with MVP than in IS patients without MVP. The persistent nature of MVP, even after corrective spinal surgery, may be related to factors other than geometric changes of the heart caused by abnormal thoracic curvature.

Sympathetic nervous system and exercise tolerance response in normotensive and hypertensive adolescents.

Comparative evaluation of isometric and dynamic exercise performance in normotensive, borderline hypertensive and hypertensive adolescents was made. Hemodynamic changes were correlated with level of adrenergic sympathetic nervous system activity as measured by plasma epinephrine and norepinephrine values. No significant intergroup differences were found with respect to isometric exercise with the exception of high peak isometric exercise heart rates and plasma epinephrine levels in the patients with significant hypertension. During dynamic treadmill testing, patients with the most marked hypertension demonstrated a statistically significantly greater tachycardia response to exercise that correlated with highest peak exercise epinephrine levels. The most hypertensive systolic dynamic exercise response was evidenced in the borderline hypertensive group in which peak exercise norepinephrine values were significantly higher than in other groups. Maximal exercise serum lactate levels were higher in hypertensive patient groups than in normotensive subjects. Altered hemodynamic response to peak dynamic exercise appears to exist in adolescents with borderline and significant hypertension and is in part mediated by altered activity of the sympathetic nervous system.

Glutaraldehyde Treated Autologous Pericardium in Complete Repair of Tetralogy of Fallot

Pericardium has been used for decades to facilitate the repair of tetralogy of Fallot (TOF). The Impact of glutaraldehyde preserved autologous pericardium when used as a right ventricular outflow tract (RVOFT) patch in TOF was analyzed in 36 consecutive children undergoing complete transventricular repair. In 18 (group 1) the pericardium was treated in conventional fashion (harvested and preserved in saline solution). In the other patients, the pericardium was treated in 0.625% glutaraldehyde solution for 20 minutes and then washed In saline prior to being implanted as an RVOFT patch (group II). The perioperative (prior to hospital discharge) as well as the 6‐month postoperative Doppler echocardiograms were assessed with 100% follow‐up. The studies were evaluated and graded by blinded observers for the presence and severity of an RVOFT dilatation (+0 to +4) relative to the size of the aortic valve annulus. The age of patients in group I and group II (29 months, 34 months) were similar as was the incidence of transannular patching (44%, 41%). Postrepair hernodynamics revealed no significant difference in the right ventricular/left ventricular pressure ratios (42%, 41%,) or in the systolic RVOFT pressure (24 mmHg, 29 mmHg). The predischarge echocardiograms showed no outflow tract (OFT) dllation in either group. There was no morbidity or mortality in either group. At approximately 6 months postoperatively (6.2 mo, 5.7 mo), 72% of group I patients had RVOFT diameters that were larger (+1, +2) than the predischarge diameters when reviewed by three observers. In group II there was a single patient with dilatation of the RVOFT and this graded as +1. The mean RVOFT dilation score in group I was 1.06 (+0.8) versus 0.06 (+0.24) in group II (p < 0.05). We conclude that dilute glutaraldehyde preservation of autologous pericardium is a safe and effective means of preventing RVOFT dilatation over the short term in patients in which a hemodynamically acceptable repair of TOF has been completed. (J Card Surg 1994;9:298–303)

Electrophysiologic studies in sick sinus syndrome following surgery for d-transposition of the great arteries

His bundle electrograms and atrial pacing are reported in a 10 1/2-year-old boy and a 12-year-old girl, both of whom underwent Mustard repair for complete d-transposition of the great arteries. Each patient had progressive evidence of sick sinus syndrome culminating in syncope. Improvement occurred after insertion of a demand pacemaker.

Troponin I as a Marker for Myocardial Injury and Ischemia during Pediatric Cardiopulmonary Bypass Surgery

Troponin I as a Marker for Myocardial Injury and Ischemia during Pediatric Cardiopulmonary Bypass Surgery

167 ALTERED SYMPATHETIC SYSTEM ACTIVITY IN A SUBGROUP OF JUVENILE ESSENTIAL HYPERTENSIVES AND SIBLINGS

Hyperactivity of the sympathetic nervous system has been implicated in the pathogenesis of essential hypertension (E.H.). To evaluate sympathetic system activity (SSA) in EH in children, we compared Blood Pressure (BP) and heart rate (HR) with Plasma Norepinephrine (PNE) and Epinephrine (PEPI) levels measured by radioenzymatic assay in resting state (RES) and after postural challenge by standing 15 Min. (STD). Subjects include 21 normal controls (NC) 19 borderline hypertensives (BH), BP>90% for age, 9 significant hypertensives (SH) BP>95% for age and 14 normotensive siblings of Hypertensives (NS) 12-18 years of age. SH had higher RES HR (73±3/Min.) than NC (66±2/Min. p<.05). RES PNE levels were significantly higher in BH (455±37 pg/Ml) and SH (373±37 pg/Ml) than N.C. (281±12 pg/M1, p<.01) or NS (316±24 pg/M1). In 13 of 19 BH (67%), 5 of 9 SH (56%) and 6 of 14 NS (43%) RES PNE levels were above highest NC level (350 pg/Ml) identifying subgroups with increased SSA at rest among Hypertensives and Normotensive Siblings. With Hemodynamic response to STD HR in SH rose more (+22+2, p<.05) than NC (+13±2) and response of mean arterial pressure (NC +13.7±2 MM Hg) was blunted in BH (+3.9+2, SH (-7.3±3) and NS (+3±3 p<.01). Some Hypertensives and NS had a hypotensive response not seen in NC. Rise in PNE was blunted in BH and SH (+40% & +48%) compared with NC (+95%). PEPI levels rose more in BH and SH than NC. PNE levels were directly and significantly related to Systolic BP LY and STD in BH & NS, not in NC. Findings offer support for hypothesis that altered SSA contributes to presence of Hypertension in some young subjects. Presence of altered SSA in some NS of hypertensives could reflect a genetic factor accounting in part for their increased risk of developing E.H.

134 PRE-AND POST-OPERATIVE RIGHT VENTRICULAR VOLUME & FUNCTION CHARACTERISTICS IN TETRALOGY OF FALLOT

Right ventricular volume and function characteristics were evaluated in 25 pre-operative and 28 post-operative patients aged 10 days to 24 years. Pre-operative patients were grouped according to the pulmonary-to-systemic flow ratio (Qp/Qs) and post-operatively according to magnitude of right ventricular (RV) peak pressure (pr.) and residual pulmonary-to-RV pressure gradients (Δ PA-RV). Pre-operatively: cardiac index (CI) was highest and pulmonary index (PI) was lowest in those with smallest Qp/Qs; RV end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV) and ejection fraction (EF)were all mildly depressed but not significantly different in various Qp/Qs groups. RV myocardial contractility index (MCI) approached normal for a systemic ventricle. Stroke work (SW) was lowest in patients with palliative left-to-right shunts (LRS). Post-operatively: EDV and ESV were elevated but highest in patients with high residual RV pr. or large Δ PA-RV. SV was normal. EF was depressed in all groups, being lowest in those with highest RV pr. or Δ PA-RV. SW and MCI were normal in low RV pr. RV outflow aneurysms were identified in 3/10 patients in the low RV pr. group and in 12/16 with highest residual pr. The incidence of pulmonary regurgitation (PR) was similar in each group. We conclude that post-operatively in patients with tetralogy of Fallot: (1) significant RV dysfunction persists being worst in those with high residual RV pr. and Δ PA-RV; (2) dysfunction is related to the incidence of RV outflow aneurysm and PR; and (3) elevated ESV results from large aneurysms with small diastolic to systolic volume change.

135 INTRACARDIAC CONDUCTION INTERVALS IN THALASSEMIA MAJOR

In the natural history of Thalassemia Major (Thal) with hemochromatosis, problems of conduction become increasingly prevalent. Intracardiac conduction intervals were measured during cardiac catheterization in 12 patients with Thal aged 11-28 years (mean 20.4 years) and compared to those of 13 normal individuals aged 14-17 years (mean 15.5 years). In Thal, hemoglobin values were 10.9 ± 1.6 Gm% at the time of study. Five of the Thal group were receiving digoxin for supraventricular arrhythmia and none were in heart failure. Normal subjects had: PH 92.2 ± 15.1 msec; AH 69.6 ± 16.5 msec; PA 23.2 ± 6.1 msec; HV 43.7 ± 6.4 msec.Significant differences were noted in Thal patients in PH and AH intervals: PH 135.0±30.0 msec (p< 0.001); AH 107.9 ± 27.1 msec (p< 0.001). The PA time [26.8 ± 9.5 msec] and HV interval [38.0 ± 5.7 msec] were similar to normal. There were no differences in any parameters between Thal patients receiving or not receiving digoxin, but those receiving digoxin had slightly longer intervals for PH and AH: PH 143.0 ± 21.1 msec vs 130.0 ± 35.6 msec (p< 0.001 vs p< 0.02 compared to normal) and AH 118.0 ± 16.8 msec vs 100.7 ± 31.8 msec (p<0.001 vs p<0.01 compared to normal). The subtle conduction delay through the AV nodal-to-His bundle area revealed by this study is the first clinical and electrophysiological documentation of deranged function and may be related to previous pathological studies showing deposits of iron in the AV nodal area in patients with hemochromatosis. Such delay may be the earliest manifestation of functional abnormality so common in adolescent and adult patients with Thalassemia Major.