Increasing trends in regional heatwaves.

Heatwaves have increased in intensity, frequency and duration, with these trends projected to worsen under enhanced global warming. Understanding regional heatwave trends has critical implications for the biophysical and human systems they impact. Until now a comprehensive assessment of regional observed changes was hindered by the range of metrics employed, underpinning datasets, and time periods examined. Here, using the Berkeley Earth temperature dataset and key heatwave metrics, we systematically examine regional and global observed heatwave trends. In almost all regions, heatwave frequency demonstrates the most rapid and significant change. A measure of cumulative heat shows significant increases almost everywhere since the 1950s, mainly driven by heatwave days. Trends in heatwave frequency, duration and cumulative heat have accelerated since the 1950s, and due to the high influence of variability we recommend regional trends are assessed over multiple decades. Our results provide comparable regional observed heatwave trends, on spatial and temporal scales necessary for understanding impacts.

Author Correction: Changes in regional heatwave characteristics as a function of increasing global temperature.

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Changes in regional heatwave characteristics as a function of increasing global temperature.

The Paris Agreement calls for global warming to be limited to 1.5-2 °C. For the first time, this study investigates how different regional heatwave characteristics (intensity, frequency and duration) are projected to change relative to increasing global warming thresholds. Increases in heatwave days between 4-34 extra days per season are projected per °C of global warming. Some tropical regions could experience up to 120 extra heatwave days/season if 5 °C is reached. Increases in heatwave intensity are generally 0.5-1.5 °C above a given global warming threshold, however are higher over the Mediterranean and Central Asian regions. Between warming thresholds of 1.5 °C and 2.5 °C, the return intervals of intense heatwaves reduce by 2-3 fold. Heatwave duration is projected to increase by 2-10 days/°C, with larger changes over lower latitudes. Analysis of two climate model ensembles indicate that variation in the rate of heatwave changes is dependent on physical differences between different climate models, however internal climate variability bears considerable influence on the expected range of regional heatwave changes per warming threshold. The results of this study reiterate the potential for disastrous consequences associated with regional heatwaves if global mean warming is not limited to 2 degrees.

Shared coronary arteries and coronary venous drainage in thoracopagus twins.

A pair of type B thoracopagus twins with complex cyanotic heart disease had shared coronary arteries and coronary venous drainage. Surgical separation was not attempted and the twins died at 10.5 months of age. Antemortem angiography demonstrated that Twin A's right coronary artery supplied Twin B's diaphragmatic and anterior ventricular myocardial free wall. A midline communication existed between each twin's right atrium at a common coronary sinus. The crossing coronary artery coursed alongside this connection and was visualized echocardiographically. At postmortem examination, the great cardiac vein of Twin A drained into the orifice of the common coronary sinus on Twin B's side of the midline. In five of six previously reported cases, the children died at attempted separation shortly after ligation of the interatrial communication. This may have been because of occlusion of a coronary artery or acute obstruction of a coronary vein. Consideration of separation of type B thoracopagus twins requires anatomic delineation of the coronary arteries and veins.

Percutaneous closure of the small patent ductus arteriosus using occluding spring coils.

OBJECTIVES: This report summarizes our experience with the use of occluding spring coils to close the small patent ductus arteriosus. BACKGROUND: Several patent ductus arteriosus occluders (most notably the Rashkind device) have been developed and studied. Occluding spring coils have been used to close abnormal vessels and vascular connections. We previously reported the use of occluding spring coils to close the small patent ductus arteriosus in a small group of patients. This report describes our series of patients having patent ductus arteriosus closure with occluding spring coils. METHODS: Between June 1990 and June 1993, 30 patients underwent cardiac catheterization to have patent ductus arteriosus closure by occluding spring coils. Selection criteria were age > 6 months and narrowest patent ductus arteriosus internal dimension < or = 3.0 mm by color flow imaging. Definitive selection was based on review of aortograms performed at catheterization. A 5.2F coronary catheter was used to deliver one or two standard occluding spring coils. A loop was delivered in the main pulmonary artery, and the remainder of the coil was delivered across the patent ductus arteriosus and into the aortic diverticulum. Patent ductus arteriosus closure was confirmed by aortography or color flow imaging, or both. Follow-up after coil placement occurred at 6 weeks and 6 months and included two-view chest radiography, echocardiography and color flow imaging. RESULTS: Of the 30 patients, 29 had successful implantation by one (27 patients) or two (2 patients) occluding spring coils. Of these 29 patients, 19 had a clinically apparent and 10 had a silent patent ductus arteriosus. Average ductus minimal internal dimension was 1.7 mm (range 1.0 to 3.0). Complete closure of the ductus was confirmed in 27 patients by aortography or color flow imaging or both (in 24 within 4 h, in 2 after 6 weeks and in 1 after 6 months). Six weeks after implantation, two patients had a tiny residual patent ductus arteriosus noted on color flow imaging. One patient did not have successful implantation. This patient had a 3.2-mm ductus, and two coils migrated to the distal left pulmonary artery and could not be retrieved. There were no deaths or any significant complications noted during early or late follow-up in these patients. CONCLUSIONS: Occluding spring coils may have additional application in closing the small patent ductus arteriosus.

Congenital heart disease and pulmonary artery hypertension. I. Pulmonary vasoreactivity to 15% oxygen before and after surgery.

Pulmonary vasoreactivity at sea level was studied in 22 children before and in 15 children after corrective cardiac surgery for congenital heart disease and pulmonary artery hypertension; 8 children were studied both before and after cardiac surgery. During cardiac catheterization in 28 children, pulmonary and systemic hemodynamics were determined in room air and during breathing of 15% oxygen, which corresponds to a maximal hypoxic level commonly encountered during airplane travel. Before surgery, 19 of 22 children tolerated 15% oxygen (O2), which caused the following hemodynamic changes from room air status: the ratio of pulmonary to systemic arterial pressure increased from 0.70 to 0.78 (p less than 0.05), the ratio of pulmonary to systemic flow decreased from 2.2 to 2.0 (p greater than 0.05) and the ratio of pulmonary to systemic vascular resistance increased from 0.33 to 0.40 (p less than 0.02). In two children, severe pulmonary vasoconstriction developed within 5 minutes of 15% oxygen administration, requiring immediate discontinuation of hypoxia; neither patient had lasting deleterious effects. There was no evidence of increased pulmonary vasoreactivity in children with Down's syndrome compared with genetically normal children. After corrective surgery in 15 children (including both of the hyperreactors), no significant pulmonary vascular response to 15% oxygen was found. It is concluded that, in a small number of children with unrepaired congenital heart disease and pulmonary artery hypertension, pulmonary vascular hyperreactivity can be induced by breathing 15% oxygen; this reaction is life-threatening but reversible with the administration of 100% oxygen.(ABSTRACT TRUNCATED AT 250 WORDS)

Pediatric cardiac catheterization with same-day discharge.

A system was developed for cardiac catheterization in children without overnight hospital stay (called same-day discharge). Over a 4 year period, 233 children (aged 5 weeks to 20 years) had catheterization with same-day discharge staying an average of 11.8 hours in the hospital. In all but 1, no problems occurred after hospital discharge; 1 child required readmission for psoas tendinitis after retrograde aortography. Same-day discharge was safely applied regardless of the patient's age, diagnosis, and use of systemic heparinization, large-bore sheaths, retrograde arterial catheterization, or cineangiography. The hospital-related cost of pediatric cardiac catheterization was reduced 29% compared with that of the standard 42 hour hospital stay. Same-day discharge provides attractive elements to the physician and institution involved in cardiac catheterizations, for example: (1) improved medical care by a decrease in the length of hospitalization, (2) a significant reduction in medical costs, and (3) elimination of time pressure in training and teaching as well as therapeutic decision-making. Critical factors for the successful application of same-day discharge are coordination of multiple health care professionals and physician judgment of the patient's clinical status. We speculate that reassessment of other hospital-oriented procedures may foster the development of methods for improving medical care or reducing cost, or both.

Repair of subdiaphragmatic total anomalous pulmonary venous connection without cardiopulmonary bypass.

Two neonates with asplenia syndrome, subdiaphragmatic total anomalous pulmonary venous connection, and pulmonary stenosis underwent a palliative operation without cardiopulmonary bypass. With the use of a side-biting clamp, and anastomosis was created between the pulmonary venous confluence and the right atrium. (Since children with asplenia syndrome have common mixing lesions, pulmonary venous drainage to the right atrium is not physiologically detrimental.) The descending vertical vein was ligated. A systemic-pulmonary shunt was performed. Both infants were discharged from the hospital less than 1 week after the operation. Both infants subsequently died, at 4 months and at 16 months of age. At autopsy, pulmonary venous drainage was unobstructed, with a surgical orifice 86% to 90% of the aortic anulus. We conclude that, in infants with asplenia syndrome and obstructed total anomalous pulmonary venous drainage, relief of pulmonary venous obstruction can be accomplished without cardiopulmonary bypass.

The bidirectional cavopulmonary shunt.

The bidirectional cavopulmonary shunt improves systemic arterial oxygen saturation without increasing ventricular work or pulmonary vascular resistance. Since 1983, 17 patients have undergone a cavopulmonary shunt procedure (five primary operations, 12 secondary operations). Diagnoses were single ventricle complex (n = 4), hypoplastic right heart syndrome (n = 10), and hypoplastic left ventricle (n = 3). Age at primary operation ranged from 3 1/2 to 30 months (median 6 months). Weight ranged from 3.5 to 9.7 kg. Age at secondary operation ranged from 10 months to 14 years (median 15 months). Seven cavopulmonary shunt operations were performed without cardiopulmonary bypass (six via thoracotomy and one via sternotomy) and 10, with cardiopulmonary bypass. All patients in the bypass group had additional procedures: takedown of modified Blalock-Taussig shunt, seven patients; revision of right ventricular outflow tract, four patients; reconstruction of pulmonary arteries, four patients; tricuspid valvuloplasty, one patient; and Damus procedure, one patient. There was one (1/17) operative death (Damus procedure). One patient required early revision. Follow-up ranges from 1 to 53 months (median 23 months). Twelve of 16 had a good to excellent late result, with a rise in mean arterial oxygen saturation from 69% to 83%. Three patients died late (4 to 53 months) (pulmonary vascular disease, pulmonary arteriovenous malformations, and pneumonia, one patient each). There was one late failure (converted to Glenn shunt). The cavopulmonary shunt is an excellent palliative procedure when right atrium-pulmonary artery connection (modified Fontan) must be deferred because of age, weight, or anatomic considerations. Five patients have undergone right atrium-pulmonary artery connection later. In addition, at the time of the modified Fontan operation, the cavopulmonary shunt approach may optimize the anatomic connection (eight additional patients).

Vascular consequences of subclavian artery transection for the treatment of congenital heart disease.

The acute and chronic consequences of subclavian artery transection were analyzed in the noninvasive vascular laboratory. Twenty-eight patients (aged 1 day to 4 2/12 years, median 2 months) underwent subclavian artery transection (23 Blalock-Taussig, four subclavian aortoplasty for coarctation or interrupted arch, and one division of aberrant left subclavian). Bilateral systolic brachial artery pressure (BAP) was measured by Doppler instrumentation to obtain a "BAP index": BAP1 = (operated side BAP/control side BAP). Velocity waveform tracings and bilateral forearm skin temperatures were also obtained during studies before and sequentially after operation (4 hours to 12 years). Five patients underwent exercise testing of the upper extremity. Nine patients were studied for manual preference and limb development. Before operation, mean BAP1 was 0.99. Immediately (4 to 48 hours) after operation, mean BAP1 was 0.39. Three weeks postoperatively, BAP1 was 0.62, and thereafter it remained at 0.70. All differences between preoperative, immediate postoperative and late postoperative BAP1 are significant (p less than 0.001). Exercise resulted in a significant (p less than 0.01) increase in BAP bilaterally. Forearm skin temperature was initially lower (p less than 0.01) on the operated side but approximated the control side by 1 week. Limb girth was less on the operated side (p less than 0.01), without evidence of altered manual preference. In conclusion, subclavian artery transection causes permanent reduction in BAP1. The affected limb appears to respond to increased metabolic demand by increasing limb blood flow.

Coarctation in the first year of life. Patterns of postoperative effect.

From 1975 to 1982, 31 infants were operated upon in the first year of life for aortic coarctation and congestive heart failure. Operations performed were resection and end-to-end anastomosis (RETE) in 14, subclavian flap aortoplasty (SFA) in six, patch aortoplasty (PA) in five, and other procedures in six. Thirty of the thirty-one (97%) survived the operation. To assess the effect of operation, 26 infants were studied noninvasively with Doppler arm-to-leg pressure measurements at rest and with stress. Preoperatively, the median arm-to-leg gradient at rest was 77 mm Hg. Serial postoperative Doppler studies demonstrated progressive changes in arm-to-leg pressure gradients: 69% had residual arm-to-leg gradients that spontaneously resolved, 13% had residual gradients that persisted, 13% had progressive increase in gradient, and one child had neither early nor late gradient. Stress testing often unmasked gradients not present in the resting state. No differences were noted among the three surgical groups: RETE, SFA, and PA. From our experience, we have made four conclusions with regard to repair of coarctation of the aorta in infants. First, surgical survival is expected. Second, the effect of the operation is dynamic, with four patterns defined: (1) complete relief of coarctation, (2) transient residual coarctation, (3) persistent residual coarctation, and (4) recurrent coarctation. Third, optimal surgical therapy seems to be an eclectic approach. Fourth, physiological evaluation of coarctation in infants can be obtained by Doppler techniques in conjunction with stress testing.

Systemic-pulmonary shunts in infants and children. Early and late results.

From September, 1978, to January, 1983, 44 cyanotic infants and children underwent a systemic-pulmonary artery shunt for the treatment of reduced pulmonary blood flow. Age ranged from 18 hours to 4 years (mean age = 0.49 years). Weight ranged from 1.7 kg to 13.2 kg (mean weight = 4.9 kg). There were 12 classic Blalock-Taussig shunts, five central polytetrafluoroethylene shunts, six interposition modified Blalock-Taussig shunts, and 21 Great Ormond Street type of modified Blalock-Taussig shunts. No direct aorta-pulmonary artery anastomoses were performed. There was one postoperative death (1/44 = 2.3%) in a 1,700 gm neonate born with pulmonary atresia and intact ventricular septum (shunt patent). Four shunts required early revision: one thrombosed central shunt, a kinked patent interposition Blalock-Taussig shunt, a small but patent Blalock-Taussig shunt, and one excessive Great Ormond Street type of Blalock-Taussig shunt. Two late deaths were probably shunt-related: one Blalock-Taussig and one central. All four types of shunts provided good palliation, but the Great Ormond Street type of Blalock-Taussig shunt is our preferred shunt because of (1) low operative risk, (2) predictable patency (100% in our series), (3) lack of distortion of pulmonary arterial anatomy, and (4) technical ease of insertion as well as takedown.

The Damus-Fontan procedure.

The Damus-Kaye-Stansel operation is a useful technique for the treatment of complex cyanotic congenital heart disease when there is obstruction between the systemic ventricle and the aorta. Modifications of the technique include transection of the aorta and the pulmonary artery, anastomosis of the contiguous aortic and pulmonary walls, and connection of the distal aorta to the perimeter of the new bivalved proximal great artery. In addition, the bidirectional cavopulmonary shunt technique can be used with or without the Fontan procedure. Six patients underwent a Damus-Fontan operation, and all survived. Two patients underwent the Damus-cavopulmonary shunt (hemi-Fontan) procedure, and 1 survived. The postoperative status of the 7 survivors is good to excellent. Follow-up ranges from 2 months to 7 1/2 years.

Late reoperation for systemic atrioventricular valve regurgitation after repair of congenital heart defects.

Since 1979, 17 infants and children have undergone reoperation for systemic atrioventricular (AV) valve regurgitation 6 weeks to 7 years after repair of congenital heart defects. Prior operations were repair of incomplete or complete AV canal (14 patients), Mustard repair of complex transposition of the great arteries including ventricular septal defect closure (2 patients), or first-stage operation for hypoplastic left heart (1 patient). Age ranged from 6 months to 11 years. In 12 of the 17 patients (10, AV canal; 1, transposition; 1, hypoplastic left heart), valve reconstruction was possible. Operative techniques included a combination of septal cleft approximation, leaflet resection, commissural annuloplasty, or ring annuloplasty. There were no operative deaths, and there were no reoperations in the repair group. The condition of these patients has improved. Follow-up ranges from 1 month to 9 years (mean follow-up, 4.1 years). Five of the 17 patients (4, AV canal; 1, transposition) underwent valve replacement. There were no operative deaths. Follow-up ranges from 3 to 8 years. Three patients later underwent re-replacement of the prosthetic valve; there was 1 late death. The condition of all 4 survivors is improved. Substantial AV valve regurgitation can occur months or years after repair of congenital heart defects. A combination of reconstructive techniques may be useful in preserving native valve function and avoiding systemic AV valve replacement.

Two-dimensional echocardiographic discrimination of normal from abnormal great artery relationships.

A prospective study was performed to determine the diagnostic accuracy of precordial two-dimensional echocardiographic techniques in discriminating normal from abnormal great artery relationships. We studied 503 children using standard parasternal short-axis view and a modified technique called rotating high long-axis view (RHLAV). In RHLAV, there is rapid superimposition of the proximal courses of the two great arteries seen by rotation of the ultrasonic beam. Discrimination was based on the crossing great artery relationship seen with normally related great arteries (NRGA) and the parallel courses found in both transposition and malposition of the great arteries (TGA/MGA). Using the RHLAV, the great artery interrelationship was accurately determined in all 503 patients. Precordial two-dimensional echocardiography can accurately discriminate great artery relationships and is a useful addition to other two-dimensional echocardiographic techniques.

Prostaglandins: physiological and clinical correlations.

This review has necessarily been incomplete. We have not considered the potentially important interplay between PGs and male and female reproductive functions or the well-documented relationships between PGs and inflammation. We have examined the evidence for the influence of PGs on the pulmonary and peripheral vascular circulations and the interaction between PGs and the kidney and the autonomic nervous system. Emphasis has been placed on the role of PGs in the control of the circulation of the ductus arteriosus, and our recent experiences with indomethacin in sick, preterm infants with large left-to-right ductal shunting have been outlined. Existing information has been reviewed concerning PGs and the fetal-placental and fetal-maternal units. It should be clear that a host of proposed functions exists for PGs; many remain tentative in light of the conflicting and often bewildering results of animal experimentation.

In situ physiological study of the developing heart.

Studies on cardiac muscle and whole heart isolated from the fetal and newborn lamb and adult sheep reveal striking age-dependent differences in cardiac ultrastructure, passive and active length-tension properties, force-velocity relationships, the compliance characteristics of both ventricles, myocardial energetics, and in the development of myocardial autonomic control. Isometric force development and both the extent and velocity of shortening at any load are reduced in the fetus when compared with the adult because of age-related changes in the proportion of myocardial tissue consisting of myofilaments. The distensibility characteristics of both the left (LV) and right ventricles (RV) are comparable in the fetal lamb close to term. In the early newborn period the RV has compliance characteristics similar to the RV of the fetus, whereas the LV alters its stress-strain characteristics to resemble the adult. Most recently, methods have been developed for the chronic evaluation of fetal left ventricular function. Internal LV dimensions and pressures are monitored continuously from midgestation beyond delivery.

Distribution of fetal cardiac output: importance of pacemaker location.

Important questions exist about the relative roles of changes in heart rate versus extent of myocardial shortening in regulating fetal cardiac output, because increases in heart rate created by left atrial pacing have been shown to increase right ventricular output and decrease left ventricular output. Since the pacemaker site could importantly influence foramen ovale flow and, hence, each ventricle's output, changes in individual ventricular outputs were examined when both the right and left atria were paced at a rate of 270 beats/min in five acute and in eight chronically instrumented fetal lamb studies. With pacing of either atrium, total cardiac output was unchanged compared to control values. However, the right ventricle contributed more to total cardiac output with left atrial pacing (73% acute, 65% chronic) than with right atrial pacing (51% acute, 57% chronic). Converse changes were observed in left atrial pacing (27% acute, 35% chronic) as compared to right atrial pacing (49% acute, 43% chronic). Thus the disparity that exists normally in the contributions of the right and left ventricles to total cardiac output is accentuated with left atrial pacing and minimized with right atrial pacing. Pressure measurements demonstrated changes in the atrial pressure relations that would be expected to alter flow across the foramen ovale depending on the chamber initially activated. Previous experimental differences can, therefore, be attributed to changes in the magnitude of shunting across the foramen ovale and depend on pacemaker location.

Axial left ventriculography in discrete subaortic stenosis.

Left ventricular angiograms of six children were reviewed, and it was found that those obtained in axial (long axial oblique and hepatoclavicular) projections enhanced precision in the diagnosis of subvalvular aortic stenosis. The methods for obtaining these views are described, and the results presented. Axial views are never inferior to standard (posteroanterior, lateral, and right anterior oblique) projections, and are usually superior to them, especially when there are associated lesions, such as ventricular septal defects, left-sided obstructive lesions, and patent ductus arteriosus.

Omental transfer for the treatment of mediastinitis in an infant.

Mediastinitis following congenital heart surgery is relatively uncommon but is usually seen in the setting of postoperative low cardiac output. Conservative treatment utilizing debridement and irrigation is associated with significant morbidity and mortality. We report the successful application of the omental transfer technique in the treatment of mediastinitis in a 6 month old.