Alpha adrenergic contributions to dysrhythmia during myocardial ischemia and reperfusion in cats.

Alpha compared to beta adrenergic contributions to dysrhythmias induced by left anterior descending coronary occlusion and by reperfusion were assessed in chloralose-anesthetized cats (n = 96). Alpha receptor blockade with either phentolamine or prazosin significantly reduced the number of premature ventricular complexes during coronary reperfusion (321 +/- 62-14 +/- 10 premature ventricular complexes, P less than 0.001), abolished early ventricular fibrillation (from 25% in controls to 0%), and prevented the increase in idioventricular rate seen with coronary reperfusion. However, beta-receptor blockade was without effect. Ventricular dysrhythmias induced by coronary occlusion alone (without reperfusion) were attenuated markedly by alpha-receptor blockade under conditions in which perfusion (measured with radiolabeled microspheres) within ischemic zones was not affected. Alternative sympatholytic interventions including pretreatment with 6-hydroxydopamine to deplete myocardial norepinephrine from 8.8 +/- 1.4 to 0.83 +/- 0.2 ng/mg protein and render the heart unresponsive to tyramine (120 microgram/kg) attenuated dysrhythmias induced by both coronary occlusion and reperfusion in a fashion identical to that seen with alpha-receptor blockade. Although efferent sympathetic activation induced by left stellate nerve stimulation increased idioventricular rate from 66 +/- 6 to 144+/- 7 beats/min (P less than 0.01) before coronary occlusion, this response was blocked by propranolol but not by phentolamine. In contrast, during reperfusion the increase in idioventricular rate induced by left stellate nerve stimulation (to 203 +/- 14) was not inhibited by propranolol but was abolished by phentolamine (79 +/- 10). Intracoronary methoxamine (0.1 microM) in animals depleted of myocardial catecholamines by 6-hydroxydopamine pretreatment did not affect idioventricular rate before coronary occlusion. However, early after coronary reperfusion, methoxamine increased idioventricular rate from 33 +/- 7 to 123 +/- 21 beats/min (P less than 0.01). Thus, enhanced alpha-adrenergic responsiveness occurs during myocardial ischemia and appears to be primary mediator of the electrophysiological derangements and resulting malignant dysrhythmias induced by catecholamines during myocardial ischemia and reperfusion.

Results of valve reconstruction for mitral regurgitation secondary to mitral valve prolapse.

Mitral valve prolapse (MVP), often the result of myxomatous degeneration of the mitral valve, is the most commonly known pathologic entity leading to pure mitral regurgitation (MR). Reconstruction of the mitral valve rather than replacement is particularly applicable to this pathologic defect, but is not often used in the U.S. Experience with reconstruction of the mitral valve for MR secondary to MVP during the period January 1970 to January 1984 was reviewed. A total of 479 patients with mitral valve disease underwent operation during this period, 82 (17%) of whom had MR secondary to MVP. Thirty-one patients (6%) had valve reconstruction by a technique of leaflet plication and posteromedial anuloplasty. Eleven of these patients had associated cardiac disease requiring correction: 2 requiring aortic valve replacement and 9 requiring coronary artery bypass grafting procedures. One hospital death (3%) and 6 late deaths (19%) occurred, of which only 3 were related to cardiac factors. Major complications included recurrent MR in 5 patients and cerebral embolus in 1 patient. The adjusted 5-year survival rate was 89 +/- 6 (mean +/- standard error of the mean), and the overall survival rate of patients free of cardiac-related complications was 73 +/- 9%. Thus, reconstruction of the mitral valve is a highly effective surgical approach to the management of symptomatic patients with MR secondary to MVP, and its use is favored over replacement in the management of these patients.

Variable morphology of ventricular septal defect in double inlet left ventricle.

The morphologic characteristics of ventricular septal defect (VSD) relative to the disposition of the atrioventricular conduction axis were studied (as far as was possible from gross observation) in 33 hearts with double inlet left ventricle. The hearts were separated into 4 groups. The hearts had either right-sided or left-sided rudimentary right ventricles (RV) coexisting with either ventriculoarterial (VA) concordance or discordance, respectively. Significant differences were noted in the morphology of the VSD according to these patterns. With right-sided rudimentary RV and VA concordance the anatomy was similar to that of classic tricuspid atresia, with an extensive outlet septum in the roof of the defect. With left-sided rudimentary RV and VA concordance, 2 further patterns were seen. In 1 pattern the arrangement was similar to that found with VA discordance. In the other, there was a pinhole VSD, a grossly hypoplastic right ventricle and a complete subaortic infundibulum in the dominant left ventricle. With VA discordance the morphology was broadly similar be the rudimentary RV right-sided or left-sided. The outlet septum was much less extensive than in the arrangement with right-sided RV and VA concordance. Minimal differences related to the formation of the right margin of the defect, which always carried the conduction axis on its left ventricular aspect. These differences dictated the "safest margins" of the defect should its excision be required during life. Basically, the left margin of the apical trabecular septum can most safely be excised.

Subaortic stenosis in childhood: frequency of associated anomalies and surgical options.

In a 4-year period from July 1984 to July 1988, 21 children required surgical treatment for subaortic stenosis. Age at operation ranged from 12 months to 17 years (mean, 7.3 +/- 4.8 years). Associated anomalies were common and occurred in 13 patients (62%), including aortic valve insufficiency (eight), and stenosis (two), mitral valve stenosis (two) and insufficiency (one), and pulmonary valve stenosis (two) and absent pulmonary valve syndrome (one). A ventricular septal defect was present in five patients, and coarctation and patent ductus arteriosus occurred in three patients each. One patient had a complete atrioventricular septal defect, and one had an aortopulmonary window. Six patients had 15 previous procedures. The left ventricular to aortic gradient ranged from 20 to 170 mm Hg (mean, 59 +/- 43 mm Hg). The operation consisted of a transaortic resection (17), transventricular septal defect resection (two), a modified Konno procedure or septoplasty with preservation of the aortic valve (one), and a combined aortoventriculoplasty with homograft reconstruction of the ascending aorta and coronary reimplantation (one). There were no early deaths. One patient required pacemaker insertion for heart block. Follow-up ranged from 1 to 48 months (mean, 26.4 +/- 11.6 months). There was one late death 2 years after operation in the child with the aortopulmonary window who had Heath Edwards Type IV changes on a lung biopsy specimen at the original operation. One patient required reoperation for a residual gradient of 34 mm Hg 1 year after resection. Three patients still have aortic insufficiency. No cases of iatrogenic aortic valve injury occurred. Patients with subaortic stenosis represent a heterogeneous group. Early resection and additional procedures can be performed with a low mortality rate and can eliminate aortic insufficiency in many cases.

Surgical repair of double-chambered right ventricle with or without ventriculotomy.

Double-chambered right ventricle is an uncommon congenital anomaly consisting of obstruction of the trabecular zone of the ventricle by an elevated, hypertrophied moderator band, with or without additional muscle bundles(s). During an 18 month period (August 1984 to February 1986) 12 patients underwent repair of double-chambered right ventricle. Their ages ranged from 13 months to 12 years (mean 4.4 years). Associated lesions were ventricular septal defect in 11 patients (three closed spontaneously), atrial septal defect in two, left superior vena cava in three, aortic valve prolapse in one, and mild subaortic stenosis in two. Right ventricular outflow tract gradients were from 30 to 165 mm Hg (mean 77.2 +/- 37.3 mm Hg). The initial six patients (Group 1) were treated in the "classical" manner with a right ventriculotomy for muscle resection and ventricular septal defect closure (4/6). All patients survived. Five of the six required pharmacologic support for signs of mild to moderate right ventricular failure. The right ventricular outflow tract gradient postoperatively was 0 mm Hg in five patients and 25 mm Hg in one patient. Oxygen saturations were checked in the right atrium and pulmonary artery in all six patients, and one patient had a step-up of more than 10%. In the next six patients (Group 2) a previously unreported right atrial-pulmonary artery approach was used to avoid a ventriculotomy. The right ventricular outflow tract gradient was 0 mm Hg in five patients and 5 mm Hg in the sixth. A ventricular septal defect was closed in four of the six patients. There were no deaths, and no patient required inotropic support. Follow-up has been from 2 to 20 months. There have been no late deaths, and all patients are asymptomatic. One patient in Group 1 still has signs of a residual ventricular septal defect at 1 year. No patient has echocardiographic evidence of right ventricular outflow tract obstruction. All patients have remained in sinus rhythm with right bundle branch block. No patient has been recatheterized. Repair of double-chambered right ventricle is easily performed without a ventriculotomy. The atrial exposure of the ventricular septal defect is excellent. The muscle bundle(s) can be visualized easily through an initial transverse pulmonary arteriotomy with completion of resection through the tricuspid valve.

Surgical palliation of subaortic stenosis in the univentricular heart.

Seventeen patients with a univentricular atrioventricular connection and subaortic stenosis at the outlet foramen level were seen from 1974 until 1983. The ventricular anatomy was of a single left ventricle with an outlet chamber, and the great arteries were transposed. This condition often followed pulmonary artery banding (15 cases) but also occurred with pulmonic stenosis (one) or pulmonary atresia (one). The median interval to the detection of subaortic stenosis after banding was 2.3 years (range 11 days to 15 years). Thirteen patients had a resting gradient to 118 mm Hg and three a gradient only with isoprenaline infusion. The following surgical procedures have been performed: (1) insertion of a conduit between the left ventricle and aorta (one patient); (2) creation of an aorticopulmonary window proximal to the band and tightening of the band (three patients); (3) enlargement of the ventricular septal defect (three patients); (4) Fontan procedure (five patients); and (5) Fontan procedure plus arterial switch (two patients). All of the procedures but the last one have met with significant mortality in this difficult group of patients.

Origin of pulmonary artery branch from ascending aorta. Primary surgical repair in infancy.

1. Surgical repair of origin of a pulmonary artery branch from the ascending aorta should be performed as early as possible in order to prevent death from congestive heart failure or the development of irreversible pulmonary vascular obstructive disease. 2. Deep hypothermic circulatory arrest greatly facilitates surgical repair of this lesion in infancy, as is illustrated by the three cases reported herein. 3. Direct anastomosis of the ectopic pulmonary artery branch to the main pulmonary artery is the surgical technique of choice. 4. Origin of the RPA or the LPA from the ascending aorta results from origin of the RPA or LPA from the aortic sac, instead of from the confluent sixth arches. Typically, the RPA has failed to migrate leftward because of abnormal development of the wall of the aortic sac, abnormal development of the sixth arches, or both. 5. Origin of the RPA or the LPA from the ascending aorta should be distinguished from origin of the "RPA" or of the "LPA" from the innominate artery or from the aortic arch via a PDA or a collateral artery.

Of clefts, commissures, and things.

A full understanding of the morphology of atrioventricular septal defects ("endocardial cushion defects," "atrioventricular canal malformations") demands knowledge of the exact nature of three specific breaches in the skirt of valve leaflet tissue guarding the atrioventricular junction. One of these is the space between the left ventricular components of the two leaflets that are enclosed in both the right and left ventricles (the bridging leaflets). Traditionally described as a cleft, it has been suggested more recently that this gap functions as a commissure. The second space is that which is found anteriorly and superiorly in the so-called Rastelli type A malformation. This is also called a cleft in a common anterior leaflet, but it has been suggested that it too is a commissure. The final breach is that produced by the surgeon when he divides the free-floating superior bridging leaflet if repairing the so-called Rastelli type C malformation with a one-patch technique. It is generally agreed that this breach be considered a division. To adjudicate the nature of the other breaches, it is necessary to compare them with commissures in atrioventricular and arterial valves and with the isolated cleft that exists in the aortic leaflet of a normal mitral valve. These considerations show that the gap between the left ventricular components of the bridging leaflets functions as a commissure even though it is not supported by a papillary muscle. This would not be expected, since the commissural attachments of the leaflets are in the left and right ventricle, respectively. The gap seen anteriorly in the Rastelli type A malformation is also a commissure, being supported in typical fashion by the medial papillary muscle of the right ventricle.

Further observations on the morphology of atrioventricular septal defects.

Certain morphologic aspects of atrioventricular septal defects ("endocardial cushion defects," "atrioventricular canal malformations") remain controversial. It is still not clear which precise lesions should not be placed in this category. For example, is an "isolated" cleft of the mitral valve or a perimembranous inlet ventricular septal defect to be so described? It is also not fully accepted that the left atrioventricular valve in these lesions bears little resemblance to a morphologically mitral valve. We have investigated these problems by both observation and mensuration. We determined the junctional circumference of the left atrioventricular valve leaflets and the ventricular dimensions in 130 atrioventricular septal defects (95 with common valve orifice and 35 with separate right and left atrioventricular orifices); in 50 hearts with perimembranous ventricular septal defects (20 extending into the inlet septum and 30 with outlet or trabecular extensions); in seven hearts with isolated cleft of the mitral valve, and in 10 normal hearts. All specimens came from the cardiopathological collection of Children's Hospital of Pittsburgh. The measurements showed conclusively that the atrioventricular septal defects were all directly comparable irrespective of the detailed morphology of the atrioventricular valve or valves. The group of atrioventricular septal defects was totally discrete as compared with all the other specimens that had normal atrioventricular septation. The left atrioventricular valve in atrioventricular septal defects is basically a three-leaflet valve which differs from the normal mitral valve in terms of its leaflet, its chordal support, and the arrangement of its papillary muscle. Its only similarity with the normal mitral valve is that it resides in the morphologically left ventricle and guards the left atrioventricular junction.

Subclavian arterioplasty. Repair of coarctation of the aorta in the first year of life.

Between June, 1977, and December, 1982, 106 infants underwent subclavian flap arterioplasty for repair of coarctation of the aorta in the first year of life. This technique was utilized because of our previous experience with the end-to-end technique in 181 infants, in whom there was a recurrence rate of 42% at 5 years. The recurrence rate in 78 of the 81 survivors who have been followed up for a mean of 18.8 months +/- 15.9 months (standard error) is 17.3% at 1 year and 11.1% at 2 and 3 years postoperatively. The presence of associated disease affects mortality: only one death in 34 patients with isolated coarctation; three deaths in 24 with coarctation plus ventricular septal defect; and 21 deaths in 45 infants with coarctation and complex lesions. Our present approach in the group with coarctation plus ventricular septal defect is to repair the coarctation without banding the pulmonary artery and then to close the defect if the infant remains in failure. Operative survival was 13 of 13 without pulmonary artery banding and 11 of 14 with pulmonary artery banding.

Anomalies of the left atrioventricular valve and related ventricular septal morphology in atrioventricular septal defects.

A characteristic feature of atrioventricular septal defects is a deficiency of the inlet part of the ventricular septum that results in a "scooped out" appearance. The depth of the scoop in relation to the disposition of the atrioventricular valves has been debated. To clarify the relation between the morphology of the ventricular septum and the disposition of the atrioventricular valves, we quantified these anatomic features in 151 hearts at autopsy to determine whether those features identified particular groups within the overall lesion. We found that 137 hearts had left atrioventricular valves with three leaflets. The left valve in the other 14 hearts exhibited a dual orifice, a two-leaflet or one-leaflet arrangement, or was imperforate. These anomalies could be analyzed in terms of a sequence of diminishing formation of the commissures. Also, three-leaflet valves displayed a variability in which the angular size of the mural leaflet correlated negatively with that of the inferior leaflet. In some of the hearts with a common atrioventricular orifice, the bridging leaflets did not meet over the ventricular septum, thus creating a "gap." The mural leaflet's angular size corresponded to a deficiency of the combined inferior-mural leaflet complex. Hearts with an abnormal disposition of the left atrioventricular valve had the ventricular septum "scooped" to a greater extent than those with a common orifice, although most had separate right and left atrioventricular orifices.

Spontaneous aortic thrombosis in a neonate presenting as coarctation.

Spontaneous aortic thrombosis in the neonate is a rare entity of uncertain etiology with a high mortality. To our knowledge, this is the first report of a newborn surviving surgical treatment of spontaneous thrombosis of the thoracic aorta.

Right pulmonary artery obstruction after pulmonary artery banding.

Serial assessment of pulmonary artery flow by Doppler echocardiography was carried out in 15 infants after pulmonary artery banding. Three infants were identified as having branch pulmonary artery obstruction based on diastolic pulmonary artery flow. It is concluded that this flow profile may be specific for branch pulmonary artery obstruction after pulmonary artery banding.

Neonatal spinal cord syndrome associated with hypoplastic aortic arch and anemia.

Spinal cord syndrome is a rare postoperative complication in neonates. We describe a case occurring after surgical treatment of a hypoplastic aortic arch in the presence of anemia.

Aprotinin in children undergoing repair of congenital heart defects.

BACKGROUND: Aprotinin use in adults is increasing, and its use in children has recently been reported. METHODS: The efficacy of aprotinin in children was tested in 80 children. Patients were in four groups: reoperations (59), neonates (8), extremely cyanotic children (6), and other complex repairs (7). The results were compared with those of 55 control infants and children: reoperations (25), neonates (10), cyanotic (10) and complex (10). Treatment groups were identical in age, sex ratio, cross-clamp time, and bypass time. RESULTS: Patients treated with aprotinin had a significant reduction in chest tube drainage (16.5 +/- 9.8 versus 33.4 +/- 22.1 mL.kg-1.h-1; p < 0.001) and time to skin closure (64.2 +/- 23.7 versus 80.1 +/- 24.6 minutes; p < 0.001). Transfusion requirements were decreased in aprotinin-treated patients 4.2 +/- 3.4 versus 6.7 +/- 5.2 donors; p < 0.001). All of the control patients were exposed to at least one donor, whereas 10/80 (12.5%) of the aprotinin-treated group had no blood use (p < 0.006). There were no cases of renal insufficiency or allergic reactions in children receiving aprotinin. Three patients had thrombotic episodes: 2 superior vena caval problems and a lower extremity deep venous thrombosis. There were 3 cases of mediastinitis in the aprotinin group versus none in control patients (p < 0.05). CONCLUSIONS: We conclude aprotinin is an effective means of reducing bleeding, operating time, and donor exposure in infants and children. An increased rate of thrombosis and possibly mediastinitis are potential problems.

Transposition of the great arteries and ventricular septal defect: results with the Senning operation and closure of the ventricular septal defect in infants.

From May, 1978, to July, 1982, 46 infants ranging in age from 12 days to 12 months and in weight from 2.1 to 8.4 kg underwent repair of dextrotransposition of the great arteries (D-TGA) and ventricular septal defect (VSD) using a Senning repair and closure of the VSD. Ventricular septal defects were classified as membranous (47.8%), malaligned (28.3%), atrioventricular (AV) canal type (13.0%), subarterial (2.2%), muscular (2.2%), and multiple (6.5%). Hospital mortality was 15.2% and late mortality, 5.1%. Postoperative complications included tricuspid regurgitation (mild in 3 and severe, requiring tricuspid valve replacement, in 3), residual VSD (pulmonary/systemic flow ratio of greater than 2:1) in 3 patients (2, AV canal type and 1, multiple VSDs), pulmonary venous obstruction in 3 patients, and permanent complete heart block in 4 patients (2, AV canal type of VSD also requiring tricuspid valve replacement). Lung biopsy studies showed reversible Heath-Edwards and morphometric changes. No patient was seen with Heath-Edwards III or greater changes. In 10 patients, right ventricular end-diastolic pressures and pulmonary artery pressures at rest were within normal limits one year after operation. As the operative mortality of atrial inversion and arterial switch operations for D-TGA with VSD tends to become comparable, more extensive follow-up data, including cardiac catheterization and coronary arteriography in a large number of patients, will be necessary to establish the superiority of one approach over the other.

Epicardial cardiac source-field behavior.

The accurate determination of the spatial distribution of cardiac electrophysiological state is essential for the mechanistic assessment of cardiac arrhythmias in both clinical and experimental cardiac electrophysiological laboratories. This paper describes three fundamental cardiac source-field relationships: 1) activation fields, 2) electrotonic fields, and 3) volume conductor fields. The three cases are described analytically and illustrated with experimentally obtained canine cardiac recordings that capitalize on a recently formulated technique for in vivo cardiac transmembrane current estimation.

Order in disorder: effect of barium on ventricular fibrillation.

BACKGROUND: Drugs that prolong cardiac refractoriness can decrease defibrillation energy requirements. In particular, barium, a relatively selective blocker of cardiac Ik1 channels, produces marked decreases in defibrillation energy. The mechanism of this effect is unknown, and may relate to modulation of the effect of defibrillatory shocks, or an alteration of the pattern of ventricular fibrillation (VF) by the drug. METHODS AND RESULTS: Accordingly, the effect of barium chloride was examined, 1.1 mg/kg followed by 0.1 mg/kg/min intravenously, or saline control, on the pattern of unipolar electrograms using a 120 electrode array, during 73 episodes of VF (37 after saline, 36 after barium ). For each episode of VF, peak-dV/dt associated with local activations and mean activation-activation (ACT-ACT) intervals for the last 2 s of a 10 s episode of VF were measured for each electrode. 'Organization' in VF was measured by the variability in ACT-ACT intervals, their visually assessed pattern, and the relation between local activations on adjacent electrodes. Voltage gradients were measured at each of 40 epicardial sites for each defibrillation shock, delivered at voltages ranging from to 20% to 100% successful in defibrillation. At identical voltage shocks (400 V), mean voltage gradients before and after barium were similar: 18+/-9 and 19+/-1.2 V/cm, respectively. Mean peak -dV/dt for all activations was -8.7+/-0.5 V/s before and -7.7+/-2.8 V/s after barium, suggesting no apparent change in local conduction velocity. When the lowest voltage gradient at any site was less than 3.5 V/cm, defibrillation was successful 14% of the time (two of 14 ) during control, but 88% of the time (14 to 16) after barium infusion (P<0.01). Mean ACT-ACT intervals after barium for all episodes over all electrodes was 107.5+/-14.1 ms, significantly longer than 89.7 +/-3.9 ms after saline, indicating a 20% increase in the cycle length of fibrillation. During saline control, local epicardial electrogram patterns showed irregular, variable morphology electrograms and a mean lowest SD of ACT-ACT intervals over any electrode of 5.1+/-1.5 ms, compared with 1.2+/-0.7 ms after barium (P < 0.0001). Following barium, most unipolar epicardial electrograms showed regular, phasic activations that appear to reflect an organized, uniformly repetitive local activation pattern, suggesting spatially homogeneous and temporally regular activation wavefronts. CONCLUSIONS: During VF after barium, despite an apparently disorganized surface electrocardiographic pattern, epicardial electrogram patterns are altered and reflect a more ¿ordered', homogeneous and regular local activation. This increased order may be in part responsible for the decreased defibrillation energy requirements observed after barium.

Myocardial infarction complicated by ventricular septal rupture in a patient with polycythemia vera and minimal coronary ectasia.

Although it is known that patients with polycythemia vera (PV) are at increased risk of myocardial infarction (MI) secondary to thrombosis, ventricular septal rupture in this setting has never been reported. Ventricular septal rupture complicating a small anteroseptal MI is reported in a patient with PV and with only minimal ectasia of the left anterior descending coronary artery. Despite small infarct size these patients may be predisposed to myocardial hemorrhage, increasing the likelihood of myocardial rupture.

Aneurysm of the membranous ventricular septum producing subpulmonic outflow tract obstruction.

The authors report the case of a 31-year-old asymptomatic male who, following investigations for cardiac murmur, was found to have congenitally corrected (status solitus of the atria, left looping of the ventricles, leftward aorta in relation to the pulmonary artery [S,L,L]) transposition of the great vessels with significant right-sided ventricular outflow tract obstruction due to a large aneurysm of the membranous ventricular septum. Diagnosis was made with transesophageal echocardiography and confirmed during corrective surgery. The authors review the literature with regard to aneurysms of the membranous ventricular septum and their association with congenital heart disease, and they discuss the use of noninvasive tests aiding the diagnosis.