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Referrals are a central component of the American health care system, defining the relationship among generalists, patients, and specialists. The dynamics of the referral process as they existed in a fee-for-service medical environment will evolve under managed care, but retain the basic "Try-out" approach of the generalist and "Rule-out" approach of the specialist. A managed care, contract-based health care system alters some of the assumptions on which the referral relationship has been structured. A four-step approach to assuring quality interactions among patient, generalist, and specialist within the managed care environment is described, including: (1) engage; (2) anticipate; (3) feedback; and (4) reassess. When the referral process is structured as suggested, it can be evaluated for quality and efficacy. Armed with mutual respect and understanding, the forces that polarized specialist and generalist care in the 1980s can be redirected to enhancing patient care in the 1990s.

This article presents both the rationale behind and a framework for incorporating pediatric preventive cardiology into undergraduate medical education and pediatric residency training. Such education of physicians in the practice of preventive cardiology requires provision of not only didactic information but also training and practice in clinical skills. A combination of didactic lectures, small group discussions, interactive programs utilizing video tapes and computer programs, family and patient simulation, preventive cardiology clinics, and community cardiovascular health promotion activities all help to provide the optimal framework for an effective medical student and pediatric resident training program in pediatric preventive cardiology. Since pediatricians are in the best position to practice true primary prevention of cardiovascular disease beginning in childhood, it is essential that physicians in training understand the concepts and learn the skills needed to practice this critical component of pediatric medicine.

We performed a chronologic investigation of left (LV) and right (RV) ventricular myosin ATPase activity and hemodynamics in newborn lambs. We found an elevation in myosin ATPase activity for the LV, which was achieved by 6 to 8 weeks of age and which correlated directly with increasing ventricular stroke work. Myosin ATPase activity did not increase with age for the RV, a finding which was associated with a postnatal decrease in ventricular stroke work. These findings may represent an important postnatal adaptation of newborn myocardium to the demands of extrauterine life.

An unusual case of left ventricular outflow tract obstruction associated with severe left ventricular failure in a neonate is reported. The physical and laboratory data were consistent with the diagnosis of infantile valvular aortic stenosis. At operation, however, redundant gelatinous pedunculated tissue attached to the mitral valve annulus appeared to move through and obstruct the aortic valve during systole. The aortic valve showed only minimal thickening of the right and left coronary cusps. A distinct angiographic pattern was demonstrated during left ventricular cineangiography. In the frontal projection a large ovoid filling defect appeared to protrude through the aortic valve during systole and return to a subvalvular location during diastole. Recognition of this angiographic pattern should facilitate diagnosis and subsequent repair. Complete correction is possible by operative excision of the obstructing tissue without damaging the mitral valve. In contrast to isolated congenital infantile valvular aortic stenosis, a condition in which the valve leaflets are often primitive and deformed, aortic valvotomy and/or subsequent valve replacement are not necessary, resulting in a better long-term prognosis.

The simplicity of the ball valve with its random seating capabilities coupled with its durability, reliability, and predictability has made it the attractive choice of many surgeons. A low incidence of embolic phenomena with the Smeloff full-orifice, double-caged, bare-strutted ball valve has made us reluctant to alter the design over 17 years. Recent evaluation of the reasons for reoperation on the Smeloff mitral valve implantation in 376 cases revealed 16 cases in which development of fibrous subvalvular pannus with signs and symptoms of mitral stenosis occurred. The mean occurrence time was 7.5 years for adults and 4.6 years for children under age 8 years. No such problem has been encountered with the valve in the aortic position. Many of these patients are maintained on aspirin and Persantine alone. Valve design was explored as a possible cause of mitral subvalvular stenosis. Alterations of the design were examined in the engineering laboratory and in dog implantations by catheterization, electrophysiologic evaluation, and echocardiography. The results were encouraging.

The ventricular epicardial activation sequence (VEAS) in 15 anesthetized lambs (near term fetus to 3.5 months of age) was determined using 40 simultaneously recorded bipolar electrograms for each animal. Isochrone maps were drawn by hand using relative activation times determined from the maximum first derivative of multiplexed signals recorded and analyzed by computer from single cardiac cycles. VEAS was similar for all ages studied. Earliest left ventricular (LV) activity appeared on the caudal dorsal and/or ventral free wall. Initial right ventricular (RV) activation appeared on the ventral anterior and/or lateral surface either simultaneously with or slightly later (2.5-3.5 msec) than initial LV activation. Excitation then proceeded circumferentially and in an apicobasilar direction and terminated on the right ventricular outflow tract.(RVO). All LV and RV epicardium except RVO activated within 7.5-12.5 msec. RVO required more than 1n.5 msec to activate in 12 of 15 animals. Total duration of RVO activation never exceeded 22.5 msec in any animal. Neither the duration nor the pattern of activation of LV or RV epicardium, including RVO, changed in a consistent fashion with age. These findings are similar to the known VEAS for adult ruminants. The data indicate that the VEAS assumes the adult pattern as of late gestation and suggest that changing right and left ventricular electromechanical events do not contribute to and probably are not affected by the process of ventricular epicardial activation. Speculation Although maturational changes in right and left ventricular electromechanical events do not appear to be related to the sequence of ventricular epicardial activation, such changes may be related to the distrubution of corresponding epicardial and intramural isopotentials.

Three cases of massive congenital tricuspid incompetence in the newborn are reported and discussed from diagnostic, pathologic and etiologic points of view. The diagnosis is important as cases have been reported with spontaneous resolution.

The time necessary for aortic diastolic pressure to decrease to 50 percent of an initially selected value after dissipation of the dicrotic notch (T 1/2) was determined in newborn infants with and without pulmonary hypertension. The mean T 1/2 was 671 +/- 167 msec in seven infants with clinical evidence of pulmonary hypertension and documented right to left ductus arteriosus shunting; 849 +/- 243 msec in nine infants with clinical evidence of pulmonary hypertension but no documented right to left ductus arteriosus shunting; and 457 +/- 66 msec in eight infants with hyaline membrane disease and no clinical evidence of pulmonary hypertension or a patent ductus arteriosus. The mean T 1/2 values in the former two groups were significantly different from that in the group with no pulmonary hypertension (P less than 0.01). An evaluation of factors affecting T 1/2 leads to the conclusion that the patients with pulmonary hypertension had increased systemic vascular resistance as well. This finding has important diagnostic, etiologic and therapeutic implications.

First-year medical students at eight U.S. medical schools were surveyed by written questionnaire in 1983-1985 to determine their attitudes toward cardiovascular diseases prevention at medical school entry. An overall response rate of 92% was achieved (2,654 questionnaires), and 97% of responders provided complete and analyzable survey data. Response rates at five of eight medical schools were 98-100%, and one school each had rates of 67, 84, or 90%. Differences in mean attitude responses from school to school were small, as were differences between men and women or between blacks and whites. This survey found that entering medical students have generally positive attitudes toward the effectiveness of preventive cardiology practice as well as toward the importance of research efforts in cardiovascular disease prevention. Students frequently indicated, however, that it is "extremely difficult" to change patients' unhealthful habits and that "physician encouragement" may not be sufficient to help patients achieve more healthful behaviors. These findings could be helpful in directing educational efforts for medical students. The data suggest that major emphasis should be placed on conveying facts regarding the physicians' efficacy in clinical preventive cardiology and on teaching the skills of preventive cardiology practice. Less emphasis appears to be necessary on encouraging positive attitudes about the importance of prevention since current students' attitudes appear to be already positive in this dimension.

Fresh isolated myocardial, elastic-arterial, and valvular tissues from seven canine hearts were irradiated by argon laser. Irradiation was transmitted through 300 and 400 micron flexible quartz fiberoptic elements. Minimal power densities for vaporization of the myocardial, arterial, and valvular tissues were 80, 90, and 110 W/cm2, respectively, with maximal vaporization distances (fiberoptic tip to tissue) of 4 mm, 1 mm, and 1 mm, respectively. Irradiation of the valves at power densities approaching perforation caused contraction of the tissue. When tissue vaporization occurred, histologic examination of irradiated tissues showed a central crater surrounded by sequential layers of char, vaporization, and coagulation necrosis. These findings were common to all cardiac tissues. Additional findings unique to myocardium were a normal-appearing myocardial layer (skip-area), circumferential halo, and tissue clefts. Elastic arteries showed concentration of necrosis around the collagen and elastic fibers. Valvular damage was the most extensive and also included contraction of adjacent valvular tissue and endocardial sloughing.

Magnetic resonance (MR) images of a variety of cardiac malformations in 19 patients aged 1 week to 33 years were obtained using pulse plethysmographic- or ECG-gated spin echo pulse sequences. Coronal, axial, and sagittal images displaying intracardiac structures with excellent spatial and contrast resolution were acquired during systole or diastole. It is concluded that MR will be a valuable noninvasive method of diagnosing congenital heart disease.

Right ventricular Starling responses to acute volume infusion in newborn lambs were compared to those in older groups of lambs. When peak stroke volume/kg was reached during infusion, right ventricular end-diastolic pressures for the newborn group were significantly lower (p less than 0.001) than those obtained for older groups, in spite of significantly higher resting and peak stroke volumes in the two younger groups. Newborn lambs developed tricuspid regurgitation and right-to-left foraminal shunting, demonstrated by echocardiography, at a mean end-diastolic pressure of 7.5 mm Hg. No right-to-left shunting was noted in older lambs. This study demonstrated a blunted Starling response in the newborn lamb's right ventricle. The response to volume loading improved with maturation, but was still less than that reported for the left ventricle. Clinical implications regarding right ventricular immaturity and inadequate response to altered hemodynamic situations are raised.

We evaluated six children for syncope of unknown etiology between March, 1983, and March, 1984. All had undergone previous neurologic evaluation which was normal. Cardiac examination, chest roentgenograms, and two-dimensional echocardiograms were also normal in all of the patients. Abnormal noninvasive findings in five patients included Mobitz type II atrioventricular (AV) block (one patient), sinus bradycardia (three patients), and supraventricular tachycardia (one patient). Four patients had one or more abnormal findings at invasive electrophysiologic study including evidence of sinus node dysfunction (three patients), AV node dysfunction (three patients), and distal His-Purkinje system disease (two patients). All children had a normal right heart hemodynamic catheterization. We conclude that arrhythmias are an important cause of syncope in some children with an otherwise normal heart when neurologic causes have been excluded.

Chest roentgenograms in 13 infants and angiocardiograms in 11 infants with persistent transitional circulation (PCT) syndrome were reviewed. Chest radiographs typically revealed congestive heart failure with pulmonary venous congestion, cardiomegaly, hepatomegaly, and pleural effusions. Angiocardiography demonstrated a right-to-left shunt through the ductus arteriosus, ventricular dilatation, poor myocardial function, and ventricular emptying. Cardiopulmonary abnormalities resolved over a period of 2-6 days in survivors. PTC syndrome as seen at the authors' institution has been an important and relatively common cause of congestive heart failure and cyanosis in the newborn. The incidence of congestive failure was higher than in other reported series.

Eleven patients with a total of 17 palliative systemic-pulmonary artery shunts underwent evaluation by electrocardiogram-gated magnetic resonance imaging (GMRI). GMRI successfully imaged 11 of 17 shunts (65%), including five of nine Blalock-Taussig shunts, four of six Glenn shunts, and both aortopulmonary shunts. All shunts except for the Waterston were imaged on coronal sections during end-systole. The single Waterston shunt was seen on sagittal and transverse scans. Shunt localization and identification were facilitated by obtaining multiple, contiguous sections through the body. Glenn shunts could be imaged entirely in one section, although multiple sections were required to locate the correct plane. Blalock-Taussig shunts generally required multiple sections to image different segments of the shunt. Both aortopulmonary shunts were seen as direct side-to-side connections of the aorta and pulmonary artery. GMRI permitted assessment of the size, course, patency, and distribution of systemic-pulmonary artery shunts as well as the size and morphology of the proximal pulmonary arteries. We conclude that GMRI is a useful, noninvasive method for imaging the anatomy of systemic-pulmonary artery shunts.

We examined the left ventricular stroke volume response to fluid loading in 24 acutely instrumented newborn lambs and the right ventricular response in 12 lambs. Newborn lambs (group 1, ages 2 to 4 days) demonstrated a limited response to acute volume loading for both left and right ventricles. With maturation, the left ventricle exhibited a progressively greater ability to respond to acute volume loading, with greater peak stroke volumes achieved at higher end-diastolic pressures. The response of the right ventricle remained limited at all ages examined, with peak stroke volume achieved at lower end-diastolic pressures. We conclude that postnatal maturation of the left ventricle results in a progressively greater stroke volume response in older lambs, while the response of the right ventricle remains limited.

To determine efficacy of the Senning procedure for correction of transposition of the great arteries we performed detailed hemodynamic and electrophysiological studies in 6 consecutive children operated upon at 5-18 months of age. Cardiac catheterizations were performed 10-19 months following surgery. All patients were asymptomatic on no medication. Hemodynamic studies demonstrated no evidence of pulmonary venous obstruction, pulmonary hypertension, or left ventricular outflow tract obstruction. 1 patient had mild upper baffle limb obstruction. Angiography demonstrated tricuspid insufficiency in 2 patients and a small atrial level shunt in 1. Ambulatory electrocardiographic monitoring in 5 of 6 patients revealed multiple premature ventricular contractions in 1. Invasive electrophysiological studies for sinus node function were normal. Corrected sinus node recovery time was 36-348 ms while total sinoatrial conduction time, determined in 4 patients, ranged between 83 and 128 ms. At our institution the Senning procedure has a low incidence of residual hemodynamic or electrophysiological abnormalities. Detailed postoperative evaluation is necessary to determine extent of residual problems.

We examined the potential for laser irradiation of congenital heart defects, with the use of postmortem hearts and an argon ion laser with a flexible quartz fiber. Atrial septectomy was performed in five newborn hearts. Obstructive lesions were relieved by laser irradiation in valvular pulmonic and aortic stenosis, dysplastic pulmonary valve, pulmonary atresia, and coarctation of the aorta. To demonstrate the efficacy of in vivo cardiac laser surgery, atrial septectomy was also performed in an anesthetized dog model, under echocardiographic visualization, without change in heart rate or blood pressure. Our results demonstrate the feasibility of intracardiac and intravascular laser irradiation for palliation and repair of selected congenital heart diseases.

Electromechanical intervals of right and left ventricles were examined in newborn lambs (9 hours to 42 days). The electromechanical interval of the left ventricle did not change with maturation, while that of the right ventricle became progressively longer, resulting in an increasing ventricular mechanical asynchrony. We postulate that the pattern of developing mechanical asynchrony described may occur secondary to postnatal changes in ventricular morphology.

Between July, 1963, and July, 1983, a total of 69 patients (35 boys and 34 girls) underwent ostium primum defect repair. There were four perioperative deaths and four patients were subsequently lost to follow-up, leaving 61 children followed for 6 months to 20 years (mean 5 years). Results of surgery were assessed by cardiac catheterization in 17 of 61 patients, while the remaining patients were evaluated noninvasively. Postoperative mitral insufficiency was found to be absent in 19 patients, mild to trivial in 35, moderate in four, and severe in two. Four patients were found to have large residual atrial septal defects. Significant late postoperative arrhythmias were found in 14 of 61 patients. The types of arrhythmias included isolated complete atrioventricular block in 5 of 14, complete atrioventricular block with sinus node dysfunction in 2 of 14, and isolated sinus node dysfunction in 7 of 14. Pacemakers have been implanted in 8 of 14 of these patients. Based on this 20-year review of a large number of children: (1) ostium primum defect repair is associated with a low mortality rate, (2) residual mitral insufficiency although common is usually mild to trivial and nonprogressive, and (3) significant arrhythmias are a frequent complication and often require pacemaker implantation.

Since 1983 we have performed electrophysiologic studies in 6 patients who had previously undergone repair of an ostium primum atrioventricular septal defect. Information obtained during electrophysiologic studies was crucial in guiding appropriate pacemaker therapy in these patients. As judged from the resting electrocardiogram, sinus or junctional bradycardia was present in 3/6, atrial flutter / fibrillation in 2/6, and paced rhythm in 2 patients who had had ventricular pacemakers implanted for complete atrioventricular block. During maximal exercise testing 4 patients had reduced heart rates; 2 had sudden drops in heart rate at 1 min postexercise; 1 patient had exercise induced ventricular bigeminy; and 1 patient with atrial flutter and 2: 1-4: 1 block at rest developed 1: 1 conduction during Stage II with an effective ventricular rate of 220/min. During electrophysiologic studies, the maximum corrected sinus node recovery time was abnormal in five of the six, ranging from 410 to 5630 msec. There was no spontaneous atrial rhythm in the other patient. Complete atrioventricular block was present in 2 patients while the atrioventricular Wenckebach phenomenon occurred abnormally at atrial pacing cycle lengths greater than 450 msec in 2 others. Supraventricular tachycardia or atrial flutter/fibrillation, was either spontaneous or induced in 2/6 patients, while ventricular tachycardia was induced in 1/3 patients who underwent programmed ventricular stimulation. Electrophysiologic studies were important in unmasking severe sinus node disease in 3 patients and atrioventricular node disease in 2. We therefore recommend that electrophysiologic studies be strongly considered as part of the evaluation of conduction abnormalities following repair of ostium primum atrioventricular septal defect.

A system is presented for evaluation of heart murmurs in infants and children. The system places emphasis on identification of functional murmurs, which the physician encounters so frequently in daily practice. A three-part approach is presented which includes: (1) evaluation of cardiovascular status, (2) assessment of the heart murmur, and (3) decision regarding the need for further evaluation. This approach relieves the physician of the necessity to remember the multiple details of the many congenital cardiac lesions, and requires only the knowledge of a few easily remembered details about functional murmurs. The system enables the physician to confidently distinguish organic and functional murmurs and to decide which children need further evaluation and referral to the pediatric cardiologist.

Ductal shunting significantly affected the time necessary for aortic diastolic pressure to fall to one-half an initially selected value (t1/2). Fourteen premature infants with clinical evidence of left-to-right ductal shunting had a mean t1/2 of 277 msec (range 133 to 383 msec) compared with a mean t1/2 of 455 msec (range 332 to 567 msec) in 14 neonates with no clinical evidence of ductal shunting (P less than 0.01). Seven older infants with ductal shunting confirmed at cardiac catheterization had a mean t1/2 of 360 msec (range 240 to 392 msec). Infant catheterization data and animal studies are suggestive of an inverse relationship between the magnitude of shunt and the t1/2. The t1/2 determined by diastolic pressure analysis is a useful method for serial evaluation of ductus arteriosus shunting.

Electrocardiographically gated magnetic resonance imaging (MRI) was successfully performed in 9 patients with atrioventricular (AV) septal defect: 6 had complete AV canal and 3 had partial AV canal. The defect was readily visualized in all patients on transverse scans taken at the level of the AV valve. The size and extent of the defect could be easily determined. All patients demonstrated a similar underlying morphologic pattern on MRI scans, consisting of deficiency of the primum atrial septum and inlet ventricular septum and a "common" AV valve ring with absence of the cardiac crux. The 3 patients with isolated atrial septal defect could be distinguished from the 6 with complete AV canal by the dense, fibromuscular bridging tissue, which coursed from the AV valve to the crest of the ventricular septum, obliterating the interventricular communication. Four patients had angiographically proved ventricular hypoplasia, which was also detected by MRI. AV valves and their patterns of chordal attachment were accurately imaged in 7 patients on systolic sections; accessory chordae were identified in 6 patients. MRI is a useful noninvasive imaging modality that can depict the underlying morphologic abnormalities in AV septal defect as well as important anatomic variations.

There have been no investigations of chronologic changes in postnatal contractile state of both left and right ventricles of the newborn. Thus, we determined isovolumetric indices of contractility in 32 acutely instrumented newborn lambs (1 day to 12 wk; three exteriorized near term fetuses, and four adult sheep. These studies demonstrated a marked increase in inotropic properties of both ventricles which was especially pronounced during the first 3 days of extrauterine life (group 1, left ventricle Vmax 3.2 +/- 0.27 and VCE10 3.2 +/- 0.28 Ml (muscle lengths)/sec; right ventricle Vmax 2.1 +/- 0.2 and VCE10 2.2 +/- 0.13 ML/sec); and was associated with elevated cardiac output (428 +/- 52 cc/kg/min), largely resulting from an elevated stroke volume (2.1 +/- 0.31 cc/kg). During subsequent postnatal maturation, contractility indices of both ventricles gradually declined to values intermediate between newborn and adult ((group IV, 22 to 84 days) - left ventricle Vmax 1.78 +/- 0.13 and VCE10 1.79 +/- 0.15 ML/sec; right ventricle Vmax 1.48 +/- 0.07 and VCE10 1.31 +/- 0.3 ML/sec); associated with a corresponding decline in cardiac output (group IV, 136 +/- 38 cc/kg/min), related in large measure to a decline in stroke volume (0.76 +/- 0.13) cc/kg). Simulation of birth in exteriorized fetuses was associated with a sudden increase in contractile indices for both left (Vmax 2.1 +/- .2 leads to 3.0 +/- .3 and VCE10 2.1 +/- 0.2 leads to 3.1 +/- 0.3 ML/sec) and right (Vmax 2.0 +/- 0.2 leads to 2.5 +/- 0.2 and VCE10 1.9 +/- 0.1 leads to 2.5 +/- ML/sec) ventricles. We conclude that there is a postnatal elevation of ventricular contractile state which contributes to successful postnatal adaptation of the newborn cardiovascular system.

A 14 month old boy with suprasystemic right ventricular pressure secondary to pulmonary valvular stenosis and anular size of 10 mm underwent percutaneous balloon valvuloplasty with a 12 mm balloon. Right ventricular pressure almost doubled after valvuloplasty and the electrocardiogram revealed development of severe right ventricular strain. Both findings persisted on the following day. A postvalvuloplasty right ventriculogram demonstrated a severe systolic infundibular obstruction not present before. The patient underwent surgical relief of infundibular obstruction; successful opening of the pulmonary valve by the balloon valvuloplasty was observed. It is concluded that a balloon size 20% larger than anular size can be safe in human subjects and that infundibular obstruction may appear or even worsen after balloon valvuloplasty. Such an obstruction may be related to the severity of pulmonary valvular obstruction and a hypercontractile infundibulum.