Safety and efficacy of carvedilol therapy for patients with dilated cardiomyopathy secondary to muscular dystrophy

BACKGROUND

By the age of 20 years, almost all patients with Duchenne's or Becker's muscular dystrophy have experienced dilated cardiomyopathy (DCM), a condition that contributes significantly to their morbidity and mortality. Although studies have shown carvedilol to be an effective therapy for patients with other forms of DCM, few data exist concerning its safety and efficacy for patients with muscular dystrophy. This study aimed to evaluate the safety and efficacy of carvedilol for patients with DCM.

METHODS

A clinical trial at an outpatient clinic investigated 22 muscular dystrophy patients, ages 14 to 46 years, with DCM and left ventricular ejection fraction (LVEF) less than 50%. Carvedilol up-titrated over 8 weeks then was administered at the maximum or highest tolerated dose for 6 months. Baseline and posttreatment cardiac magnetic resonance imaging (CMR), echocardiography, and Holter monitoring were recorded.

RESULTS

Carvedilol therapy was associated with a modest but statistically significant improvement in CMR-derived ejection fraction (41% +/- 8.3% to 43% +/- 8%; p < 0.02). Carvedilol also was associated with significant improvements in both the mean rate of pressure rise (dP/dt) during isovolumetric contraction (804 +/- 216 to 951 +/- 282 mmHg/s; p < 0.05) and the myocardial performance index (0.55 +/- 0.18 to 0.42 +/- 0.15; p < 0.01). A trend toward improved shortening fraction, E/E' ratio, and isovolumetric relaxation time also was observed. Two patients had runs of nonsustained ventricular tachycardia exceeding 140 beats per minute (bpm) before carvedilol administration. Ventricular tachycardia exceeding 140 bpm was not observed after carvedilol therapy. Carvedilol was well tolerated, and no serious adverse events were identified.

CONCLUSIONS

Carvedilol therapy appears to be safe for patients with DCM secondary to muscular dystrophy and produces a modest improvement in systolic and diastolic function.

Racial and ethnic disparities in mortality following congenital heart surgery

Our objective was to assess risk-adjusted racial and ethnic disparities in mortality following congenital heart surgery. We studied 8483 congenital heart surgical cases from the Kids' Inpatient Database 2000. Black sub-analysis was performed using predetermined regional categories. For our Hispanic sub-analyses, we categorized Hispanics into state groups according to a state's predominant Hispanic group: West (Mexican-American), Southeast (Cuban-American), Northeast (Puerto Rican), and Mixed/Heterogeneous. Risk adjustment was performed using the Risk Adjustment for Congenital Heart Surgery method. Multivariate analyses assessed the effect of race/ethnicity and Hispanic state group on mortality and explored the effects of gender, income, insurance type, and region. Black children had a higher risk for death than Whites odds ratio (OR), [1.65; p = 0.003]. Hispanics and the Cuban-American state group showed a trend toward a higher death risk (Hispanic: OR, 1.24; p = 0.16; Southeast Cuban-American: OR 1.55; p = 0.08). Disparities were not influenced by insurance. Among Blacks, disparities were greatest in the Northeast region (OR, 2.25; p = 0.007). After adjusting for gender, income, and region, Blacks (OR, 1.76; p = 0.002) and Hispanics (OR, 1.34; p = 0.05) had a higher death risk. Racial and ethnic disparities in risk-adjusted mortality following congenital heart disease exist for Blacks and Hispanics. These disparities are not due to insurance but are partially explained by gender and region.

Prospective single-arm protocol of carvedilol in children with ventricular dysfunction

The objective of this study was to evaluate the safety and efficacy of carvedilol in pediatric patients with stable moderate heart failure. We performed a single-arm prospective drug trial at three academic medical centers and the results were compared to historical controls. Patients were 3 months to 17 years old with an ejection fraction <40% in the systemic ventricle for at least 3 months on maximal medical therapy including ACE inhibitors. Treated patients were started on 0.1 mg/kg/day and uptitrated to 0.8 mg/kg/day or the maximal tolerated dose. Echocardiographic parameters of function were prospectively measured at entry and at 6 months. Two composite endpoints were recorded: severe decline in status and significant clinical change. Adverse events were reviewed by a safety committee. Data were also collected from untreated controls with dilated cardiomyopathy meeting entry criteria, assessed over a similar time frame. Twenty patients [12 dilated cardiomyopathy (DCM) and 8 congenital] with a median age of 8.4 years (range, 8 months to 17.8 years) were treated with carvedilol. Three patients discontinued the drug during the study. At entry, there was no statistical difference in age, weight, or ejection fraction between the treated group and controls. The ejection fraction of the treated DCM group improved significantly from entry to 6 months (median, 31 to 40%, p = 0.04), with no significant change in ejection fraction in the control group [median, 29 to 27%, p = not significant (NS)]. The median increase in ejection fraction was larger for the treated DCM group than for the untreated DCM controls (7 vs 0%, p = 0.05). By Kaplan-Meier analysis, time to death or transplant tended to be longer in treated patients (p = 0.07). The difference in the proportion of patients with severe decline in status or significant clinical change in the treated group was not significant compared to the controls (5 vs 12%, p = NS). We conclude that in this prospective protocol of pediatric patients, the use of adjunct carvedilol in the DCM group improved ejection fraction compared to untreated controls and trended toward delaying time to transplant or death.

The RACHS-1 risk categories reflect mortality and length of hospital stay in a large German pediatric cardiac surgery population

OBJECTIVES

The Risk Adjusted classification for Congenital Heart Surgery (RACHS-1) was published in January 2002, based on 4370 operations registered by the Pediatric Cardiac Care Consortium. It is designed for being easily applicable also for retrospective analysis of hospital discharge data sets; the classification was not developed for patients with heart transplantations, ventricular assist devices or patients above 18 years. We apply this classification to our 2368 correspondent procedures that were performed consecutively on 2223 patients between June 1996 and October 2002 in Bad Oeynhausen and analyze its relation to mortality and length of hospital stay.

METHODS

The procedures were grouped by the 6 RACHS-1 categories. Groping criteria were mainly the performed procedures; for few procedures age or diagnoses are needed in addition. The classification process itself took less than 10 working hours. Risk group frequencies in our/ the PCCC population were 1: 368/964 (15.5%/22.0%), 2: 831/1433 (35.1%/33.1%), 3: 744/1523 (31.4%/34.7%), 4: 284/276 (12.0%/6.3%), 5: 4/4 (0.2%/0.1%), 6: 137/168 (5.3%/3.8%). 18.8%/19.2% were under 1 month, 37.5%/31.6% 1-12 months of age, respectively.

RESULTS

Hospital mortality (%) in our population/ the PCCC Group 1-6 was: 0.3/0.4, 4.0/3.8, 5.6/8.5, 9.9/19.4, 50.0/0, 40.1/47.7%. Geometric means of total (13.1, 19.6, 23.5, 29.1, 31.5, 52.6 days, respectively) and postoperative length of stay of survivors show significant differences between the single risk groups. The prediction capacity of the score as expressed by the area under the receiver-operator curve was nearly equal to the value found for the American hospital discharge data sets. Length of stay rises exponentially with the RACHS-1 category. However, the RACHS-1 category explains only 13.5% of the total and 16.8% of individual postoperative lengths of hospital stay in survivors.

CONCLUSION

The RACHS-1 classification is applicable to European pediatric populations, too. Category Distribution, outcome class distinction capacity, distribution and mortality are similar. RACHS-1 is able to classify patients into significantly different groups concerning total and postoperative hospital stay duration, although there remains a large variability within the groups.

Morbidities in patients with hypoplastic left heart syndrome

We sought to document morbidities and growth for patients with hypoplastic left heart syndrome (HLHS) to inform the initial surgical decision and understand healthcare needs. Data were obtained on 137 patients with HLHS, born between 1989 and 1994, who survived staged surgery ( n = 62) or transplantation ( n = 75) and had follow-up information available from four pediatric cardiac surgical centers. In patients with HLHS older than 1 year of age at follow-up, 93% experienced at least one major postsurgical morbidity. Morbidities depended on the surgery received. Hypertension, renal compromise, and abnormal infections were more common in transplanted patients than staged surgery patients. Staged surgery patients used more anticongestive medications and experienced more morbidities requiring interventional catheterization than did transplanted patients. Rejection was common for transplanted patients. On average these children spent 23 days per year in the hospital. Patients with HLHS were small for their age; 43% of staged surgery patients weighed below the third percentile at last information, compared to 19% of transplanted patients ( p = 0.003). The median height percentile was the 10th in both groups. Normal activity level was reported in more transplanted patients (90%) than staged surgery patients (49%; p < 0.001). Trade-offs between mortality and morbidity outcomes can help inform the initial surgical decision.

Health-related quality of life in children attending a cardiology clinic

Our purpose was to evaluate the impact of suspicion or confirmation of heart disease on the physical and psychosocial health of children. We utilized the Child Health Questionnaire (CHQ PF-50). Children ages 5 to 18 years attending a general cardiology clinic were eligible. Those with primary noncardiac diagnoses unrelated to heart disease were excluded. Children with similar conditions were grouped together for analysis. Group and subgroup means were compared to a U.S. population normative sample using the two-sample t test. The CHQ was administered to 321 patients (median age, 10.6 years). Overall, parents reported mean Physical and Psychosocial Summary Scores comparable to those for the normative sample (mean, 51.5 vs 53.0, p = 0.04; mean, 52.3 vs 51.2, p = 0.10). There was a trend toward worse physical health in most subgroups, especially those with cardiomyopathy (CM) (46.5; p = 0.01), and a comparable trend toward better psychosocial health except in those requiring major interventions. In subscale analyses, most subgroups reported worse Physical Functioning than the normative sample, especially CM (85.1 vs 96.1; p = 0.02). Parents of children with CM (53.2 vs 73.0; p = 0.002) and the intervention subgroups (except minor) reported worse General Health Perceptions. Parents experienced increased Parental Impact-Emotional, especially parents of children undergoing evaluations for chest pain (62.5 vs 80.3; p = 0.007). Most parents reported comparable or better health for the Family Cohesion and Bodily Pain subscales. Generally, parents of children attending a cardiology clinic report physical and psychosocial health comparable to that for the general U.S. population. However, diagnosis or confirmation of heart disease resulted in worse physical functioning and health perceptions and a significant negative emotional impact on parents.

Risk of death for Medicaid recipients undergoing congenital heart surgery

The objective of this study was to explore the effect of insurance type on mortality for congenital heart surgery. We performed a population-based retrospective cohort study using hospital discharge abstract data from five states in 1992 and 1996. The outcome measure was risk-adjusted in-hospital mortality. Cases of pediatric congenital heart surgery were identified and placed into six risk categories using the Risk Adjustment in Congenital Heart Surgery method. Multivariate analyses were used to determine the effect of insurance type on risk-adjusted mortality; regional effects were explored. Using standardized mortality ratios, institutions were grouped by outcome; within and between group differences were examined. Of 11,636 cases, 9656 (83%) were placed in a risk group for analysis. In 1996, children with Medicaid had a higher risk of death than those with commercial or managed care in both unadjusted (p = 0.002) and adjusted (p < 0.001) analyses. Overall mortality rates decreased between 1992 and 1996 (p = 0.001). However, improvement was not consistent among insurance groups. Differences were present within and between low, average, and high-mortality hospitals, suggesting that the adverse effect of Medicaid may be due to both differential referral and other differences in care among patients treated at similar institutions. Children with Medicaid insurance have a higher risk of dying after congenital heart surgery than those with commercial and some managed care insurance. Barriers to access go beyond differences in referral patterns.

Regional racial and ethnic differences in mortality for congenital heart surgery in children may reflect unequal access to care

The objective of this study was to explore racial differences in mortality for congenital heart surgery. We performed a population-based retrospective cohort study using hospital discharge abstract data from four states in 1996. The outcome measure was risk-adjusted in-hospital mortality. Cases of pediatric congenital heart surgery were classified into six risk categories using the Risk Adjustment in Congenital Heart Surgery method. Differences in risk-adjusted in-hospital mortality among racial groups were explored. Analyses stratified by state were used to identify regional differences. Of 5791 cases, 4822 (83%) were assigned to a risk group for analysis. Surgical mortality differed for whites compared to non-whites (3.7 vs 5.1%, p = 0.02). Among non-white groups, unadjusted mortality rates varied: Asian, 5.3%; black, 4.1%; Hispanic 4.9%; other, 7.3%; and missing, 7.6% (p = 0.008). Adjusted mortality also differed by race but was inconsistent across regions, making explanatory factors based solely on biology implausible. For example, compared to whites, blacks had a higher risk of dying in Massachusetts [odds ratio (OR) = 6.39, p = 0.08] but lower in Pennsylvania (OR = 0.41, p = 0.009). Adding insurance type to models did not eliminate racial differences. In risk-adjusted analyses, non-white groups had a higher risk of dying after congenital heart surgery than whites. Inconsistent effects among regions suggest that differential mortality is due to unequal access to care rather than biology.

Cytosolic targeting domains of gamma and delta calmodulin-dependent protein kinase II

Ca(2+)/calmodulin-dependent protein kinase II (CaMK-II) isozyme variability is the result of alternative usage of variable domain sequences. Isozyme expression is cell type-specific to transduce the appropriate Ca(2+) signals. We have determined the subcellular targeting domain of delta(E) CaMK-II, an isozyme that induces neurite outgrowth, and of a structurally similar isozyme, gamma(C) CaMK-II, which does not induce neurite outgrowth. delta(E) CaMK-II co-localizes with filamentous actin in the perinuclear region and in cellular extensions. In contrast, gamma(C) CaMK-II is uniformly cytosolic. Constitutively active delta(E) CaMK-II induces F-actin-rich extensions, thereby supporting a functional role for its localization. C-terminal constructs, which lack central variable domain sequences, can oligomerize and localize like full-length delta(E) and gamma(C) CaMK-II. Central variable domains themselves are monomeric and have no targeting capability. The C-terminal 95 residues of delta CaMK-II also has no targeting capability but can efficiently oligomerize. These findings define a targeting domain for gamma and delta CaMK-IIs that is in between the central variable and association domains. This domain is responsible for the subcellular targeting differences between gamma and delta CaMK-IIs.

A comparison of treatment strategies for hypoplastic left heart syndrome using decision analysis

OBJECTIVES

We sought to identify the optimal treatment strategy for hypoplastic left heart syndrome (HLHS).

BACKGROUND

Surgical treatment of HLHS involves either transplantation (Tx) or staged palliation of the native heart. Identifying the best treatment for HLHS requires integrating individual patient risk factors and center-specific data.

METHODS

Decision analysis is a modeling technique used to compare six strategies: staged surgery; Tx; stage 1 surgery as an interim to Tx; and listing for transplant for one, two, or three months before performing staged surgery if a donor is unavailable. Probabilities were derived from current literature and a dataset of 231 patients with HLHS born between 1989 and 1994. The goal was to maximize first-year survival.

RESULTS

If a donor is available within one month, Tx is the optimal choice, given baseline probabilities; if no donor is found by the end of one month, stage 1 surgery should be performed. When survival and organ donation probabilities were varied, staged surgery was the optimal choice for centers with organ donation rates < 10% in three months and with stage 1 mortality <20%. Waiting one month on the transplant list optimized survival when the three-month organ donation rate was > or =30%. Performing stage 1 surgery before listing, or performing stage 1 surgery after an unsuccessful two- or three-month wait for transplant, were almost never optimal choices.

CONCLUSIONS

The best strategy for centers that treat patients with HLHS should be guided by local organ availability, stage 1 surgical mortality and patient risk factors.

Healing response to the Clamshell device for closure of intracardiac defects in humans

The healing response to intracardiac devices in humans is largely unknown. During regulatory trials using the Clamshell device in over 800 patients, attempts were made to perform histopathological evaluation of all explanted devices. We reviewed all those with complete histopathological examination (n = 12) from Fontan baffles (n = 4), ventricular septal defects (n = 2), and atrial septal defects (ASD; n = 6), explanted at 2.7 months to 3.6 years (median, 1.6 years), at autopsy (n = 1) or surgery (n = 11), performed for residual defects (n = 5), atrial masses (n = 3), or Fontan revision (n = 3). All but one were nearly (n = 3) or completely (n = 8) covered by pseudointima, composed of fibroelastic tissue, predominantly collagen, with focal foreign body reaction in contact with fabric, without acute inflammation or infection. Atrial masses of granulation tissue were present in three cases (ASD), opposite to protruding fractured arms. No associations were identified between coverage and closure status, position, arm fractures, or implant period. In conclusion, the healing response to transcatheter Clamshell implantation in humans is characterized by a relatively rapid development of a nonthrombotic pseudointima composed of fibroelastic tissue with minimal foreign body reaction. Cathet Cardiovasc Intervent 2001;54:101-111.

Heart size on chest x-ray as a predictor of cardiac enlargement by echocardiography in children

To determine the usefulness of heart size on chest radiograph (CXR) in predicting cardiac enlargement (CE) in children, we prospectively evaluated 95 consecutive outpatients, who had both a CXR and echocardiography performed. Their median age was 5.0 years (2 days to 19.9 years). All patients underwent CXR assessment by a pediatric radiologist, with classification of cardiac silhouette as normal, borderline, or enlarged. Echocardiographic assessment of CE was performed by a pediatric echocardiographer. Sensitivity, specificity, and predictive values of the pediatric radiologist's interpretation of heart size on CXR were estimated. The presence of CE by echocardiography was used as the gold standard. Seventy-nine patients (83.2%) had no CE on CXR, and 16 patients (16.8%) had CE. Sensitivity of the CXR to identify CE was 58.8%, 95% confidence interval (CI) [32.9, 81.6], with a positive predictive value of 62.5% [35.4, 84.8]. Specificity was 92.3% [84.0, 97.1], with a negative predictive value of 91.1% [82.6, 96.4]. These data suggest that the assessment of CE on CXR to predict CE by echocardiography has a relatively high specificity and negative predictive value, but a low sensitivity and positive predictive value. The limitations of CXR as a diagnostic test should be understood by clinicians using the test when screening children for cardiac disease.

delta Ca(2+)/Calmodulin-dependent protein kinase II isozyme-specific induction of neurite outgrowth in P19 embryonal carcinoma cells

Ca(2+)/calmodulin-dependent protein kinase II (CaMK-II) has been linked to the induction of differentiation in preneuronal cells. In these cells, delta isozymes represent the majority of CaMK-IIs expressed and are activated by differentiation stimuli. To determine whether delta CaMK-IIs are causative or coincident with in vitro differentiation, we overexpressed wild-type, constitutively active, and C-terminal domains of delta and gamma CaMK-II isozymes in mouse P19 and NIH/3T3 cells using high-efficiency transfections. At 1-2 days after transfection, only constitutively active delta CaMK-II isozymes induced branched cellular extensions in both cell types. In P19 cells, retinoic acid induced neurite extensions after 3-4 days; these extensions were coincident with a fourfold increase in endogenous CaMK-II activity. Extensions induced by both retinoic acid and delta CaMK-IIs contained class III beta-tubulin in a discontinuous or beaded pattern. C-terminal CaMK-II constructs disrupted the ability of endogenous CaMK-II to autophosphorylate and blocked retinoic acid-induced differentiation. delta CaMK-II was found along extensions, whereas gamma CaMK-II exhibited a more diffuse, cytosolic localization. These data not only support an extranuclear role for CaMK-II in promoting neurite outgrowth, but also demonstrate CaMK-II isozyme specificity in these early steps of neuronal differentiation.

Clinical outcome of fenestrated Fontan patients after closure: the first 10 years

BACKGROUND

The late clinical status of Fontan patients after fenestration closure is unknown. Data are now available on all patients who underwent closure from 1989 to 1999.

METHODS AND RESULTS

All patients who underwent catheter closure of a Fontan fenestration were enrolled in either the Clamshell (1989 to 1994) or CardioSEAL (1996 to 1999) regulatory trials. Physiological values obtained at catheterization helped assess the hemodynamic effects of fenestration occlusion. In addition to survival, outcomes assessed included O(2) saturations, medication use, significant clinical findings (eg, heart failure, protein-losing enteropathy, or new arrhythmias), and somatic growth. Of 181 patients who underwent closure, 27 had additional significant leaks. The remaining 154 patients constituted the study group. Median time from closure to latest follow-up was 3.4 years (range 0.4 to 10.3 years). Fenestration closure increased O(2) saturation 9.4% on average (P:<0. 001). The numbers of patients receiving digoxin or diuretics decreased at the most recent follow-up compared with baseline (P:<0. 001), but use of antiarrhythmic agents increased marginally (P:=0. 05). Height and weight percentiles rose (medians of 2 and 4, respectively; P:<0.001). Clinical decompensation during follow-up of 154 patients was rare (4.5%), with 2 deaths, 3 Fontan revisions, and 1 patient each with protein-losing enteropathy and ascites. No other patient developed chronic congestive symptoms; 21 patients developed new arrhythmias, and 2 had a stroke or transient ischemic attack.

CONCLUSIONS

Fenestration closure in Fontan patients was followed by improved oxygenation, reduced need for anticongestive medication, and improved somatic growth at latest follow-up. Death (1.3%) or chronic decompensation (3.2%) was rare.

Survival analysis and risk factors for mortality in transplantation and staged surgery for hypoplastic left heart syndrome

OBJECTIVES

We compared survival in treatment strategies and determined risk factors for one-year mortality for hypoplastic left heart syndrome (HLHS) using intention-to-treat analysis.

BACKGROUND

Staged revision of the native heart and transplantation as treatments for HLHS have been compared in treatment-received analyses, which can bias results.

METHODS

Data on 231 infants with HLHS, born between 1989 and 1994 and intended for surgery, were collected from four pediatric cardiac surgical centers. Status at last contact for survival analysis and mortality at one year for risk factor analysis were the outcome measures.

RESULTS

Survival curves showed improved survival for patients intended for transplantation over patients intended for staged surgery. One-year survival was 61% for transplantation and 42% for staged surgery (p < 0.01); five-year survival was 55% and 38%, respectively (p < 0.01). Survival curves adjusted for preoperative differences were also significantly different (p < 0.001). Waiting-list mortality accounted for 63% of first-year deaths in the transplantation group. Mortality with stage 1 surgery accounted for 86% of that strategy's first-year mortality. Birth weight <3 kg (odds ratio [OR] 2.4), highest creatinine > or =2 mg/dL (OR 4.7), restrictive atrial septal defect (OR 2.7) and, in staged surgery, atresia of one (OR 4.2) or both (OR 11.0) left-sided valves produced a higher risk for one-year mortality.

CONCLUSIONS

Transplantation produced significantly higher survival at all ages up to seven years. Patients with atresia of one or both valves do poorly in staged surgery and have significantly higher survival with transplantation. This information may be useful in directing patients to the better strategy for them.

Mechanism of pulmonary vein stenosis in infants with normally connected veins

We used microscopy, immunohistochemistry, and cell culture to identify the mechanism of restenosis in 4 infants with isolated pulmonary vein stenosis. Recurrent obstruction appears to be due to myofibroblastic proliferation in this fatal disease.

Sudden death in patients after transcatheter device implantation for congenital heart disease

To explore whether transcatheter intracardiac devices increase risk for sudden death, we analyzed patient and device-related variables with a case-control design. Sudden death was defined as unexpected death with abrupt onset and rapid deterioration. Cases included all patients known to have died suddenly after device closure at our institution, using 3 large databases. Controls (2:1), matched on year of procedure, were chosen randomly from the same databases. Data were obtained from medical record review. Of 777 patients who received implants between February 1989 and February 1999, 9 were known to have died suddenly (1.2%). In 27 cases and controls, diverse defects were occluded: atrial (n = 16), ventricular (n = 4), Fontan fenestration (n = 4), or other (n = 3). Cases were more likely to have had a history of serious arrhythmias (p = 0.008), severe valve regurgitation (p = 0.03), > or =1 cardiac surgery (p = 0.009), and multiple devices (p = 0.03). Cases were somewhat more likely to have pulmonary hypertension (p = 0.09), ventricular dysfunction (p = 0.09), and nonatrial septal defects (p = 0.10). Patients were less likely to have device arm fractures (p = 0.05). The following were not related to sudden death: age, weight, gender, low systemic cardiac index, end-diastolic pressure, major noncardiac disease, serious adverse events, maximum device size, malposition, and residual leak. This study suggests that sudden death was more likely to occur in device-implanted patients who had severe underlying cardiac disease and/or multiple devices. No other device-related variables were associated with sudden death.

Closure of patent foramen ovale for paradoxical emboli: intermediate-term risk of recurrent neurological events following transcatheter device placement

OBJECTIVES

We report the largest and the longest follow-up to date of patients who underwent transcatheter patent foramen ovale (PFO) closure for paradoxical embolism.

BACKGROUND

Closure of a PFO has been proposed as an alternative to anticoagulation in patients with presumed paradoxical emboli.

METHODS

Data were collected for patients following PFO closure with the Clamshell, CardioSEAL or Buttoned Devices at two institutions.

RESULTS

There were 63 patients (46 +/- 18 years) with a follow-up of 2.6 +/- 2.4 years. Fifty-four (86%) had effective closure of the foramen ovale (trivial or no residual shunt by echocardiography) while seven (11%) had mild and two (3%) had moderate residual shunting. There were four deaths (leukemia, pulmonary embolism, sepsis following a hip fracture and lung cancer). There were four recurrent embolic neurological events following device placement: one stroke and three transient events. The stroke occurred in a 56-year-old patient six months following device placement. A follow-up transesophageal echocardiogram showed a well seated device without residual shunting. Two of the four events were associated with suboptimal device performance (one patient had a significant residual shunt and a second patient had a "friction lesion" in the left atrial wall associated with a displaced fractured device arm). The risk of recurrent stroke or transient neurological event following device placement was 3.2% per year for all patients.

CONCLUSION

Transcatheter closure of PFO is an alternative therapy for paradoxical emboli in selected patients. Improved device performance may reduce the risk of recurrent neurological events. Further studies are needed to identify patients most likely to benefit from this intervention.

Acute animal studies of the STARFlex system: a new self-centering cardioSEAL septal occluder

The STARFlex system is a modified CardioSEAL device with a flexible self-centering mechanism comprised of nitinol springs strung between opposing arms, a connecting ball (sleeve joint that allows the device to pivot prerelease), and a front-loading delivery system. It was designed to allow a smaller device/defect sizing ratio and delivery profile, provide centering capability, and improve closure rates. To test this system, 13 devices (23, 28, and 33 mm) were deployed in six sheep within created atrial septal defects (12- to 22-mm diameter; n = 10), in the left atrium (n = 2), and in inferior vena cava (n = 1). All implantations in atrial septal defects were successful, with device/defect ratio ranging from 1.3 to 1.9 (median, 1.3), with no residual leak by angiography or echocardiography in seven (3/10 had </= small immediate leaks). The STARFlex system was effective in closing created atrial septal defects using a 10 Fr delivery sheath and low device/defect sizing ratios, comparing favorably with the standard CardioSEAL. Cathet. Cardiovasc. Intervent. 49:225-233, 2000.

Validation of relative value scale for congenital heart operations

BACKGROUND

To determine the validity of the newly assigned work relative value unit (RVU) scale for surgical procedures for congenital heart disease, we measured its relationship to length of hospital stay, total hospital charges, and mortality.

METHODS

We identified cases by the presence of ICD-9-CM codes in nine statewide, administrative hospital discharge abstract databases for 1992. Computer algorithms were generated to assign RVUs to individual cases. Spearman correlation coefficients between work and practice expense RVUs and median length of hospital stay, total hospital charges, and in-hospital mortality were determined, as well as parameter estimates from linear and logistic regression.

RESULTS

Using data from 5,192 cases involving 34 surgical procedures for congenital heart disease, higher work RVUs were associated with longer lengths of hospital stay (rs = 0.72, p < 0.0001), higher total hospital charges (rs = 0.81, p < 0.0001), and higher in-hospital mortality (rs = 0.45, p = 0.01). A 5-point increase in the relative value scale was associated with an increase in the length of stay by a multiplicative factor of 1.3 (p < 0.0001); total hospital charges by 1.5 (p < 0.0001); and the odds of in-hospital death by 1.9 (p < 0.0001). Findings were similar for practice expense RVUs, as work and practice expense RVUs were highly correlated (rs = 0.93, p < 0.0001).

CONCLUSIONS

The group of work RVUs for surgical procedures for congenital heart defects are reasonable relative measures, on average, of physician work for these procedures, thus supporting the use of this scale to determine physician reimbursement. Practice expense RVUs may not be an independent measure for these procedures.

Intra-atrial reentrant tachycardia after palliation of congenital heart disease: characterization of multiple macroreentrant circuits using fluoroscopically based three-dimensional endocardial mapping

INTRODUCTION

The anatomic substrate of intra-atrial reentrant tachycardia (IART) following congenital heart surgery is poorly understood, but is presumed to be different than common atrial flutter.

METHODS AND RESULTS

To study the mechanisms of IART, we used a new technique for high-density endocardial mapping using recordings from a multipolar basket recording catheter (25 bipolar pairs). For each recording, biplane fluorographic reference points were digitized to obtain the spatial locations of electrode pairs, and activation times were calculated using temporal reference points from the surface ECG. Using custom software, data were combined to create three-dimensional atrial activation sequence maps, which were displayed as animated sequences. Using this technique, recordings were made in induced and/or spontaneous IART in 8 patients following congenital heart surgery (5 Fontan, 2 tetralogy of Fallot repair, 1 ventricular septal defect repair), and in 3 patients with normal intracardiac anatomy (1 with type I atrial flutter). Ten discrete IART activation sequences were recorded; 2 patients had 2 sequences each. IART maps were constructed using a median of 108 electrode positions (range 27 to 197) from a median of 6 recordings/sequence (range 3 to 11). Sinus or paced atrial rhythms were also recorded, and maps were created in a similar fashion. Visual analysis of activation sequences of sinus and paced rhythm were anatomically concordant with known mechanisms of atrial activation. IART sequences revealed diverse mechanisms; only 1 IART circuit was similar to that associated with common atrial flutter. Activation wavefront emergence from presumed zones of slow conduction, lines of conduction block, and apparent bystander activation were observed.

CONCLUSIONS

High-density atrial activation sequence maps demonstrate that IART following congenital heart surgery utilizes diverse circuits and is distinct from common atrial flutter. The technique used to create these three-dimensional activation sequences may improve understanding of these complex atrial arrhythmias and assist in the development of ablative therapies.

Multipolar endocardial mapping of the right heart using a basket catheter: acute and chronic animal studies

The development of catheter-based ablative techniques for primary atrial and ventricular arrhythmias is likely to be assisted by improved techniques for systematic endocardial activation sequence mapping. RA mapping using a multielectrode basket catheter has been shown to be feasible with minimal acute toxicity in a prior study. The objectives of the current study are to investigate: (1) the utility of the basket catheter for mapping RV activation; and (2) the evolution of acute endocardial lesions produced by basket catheter use in both the RA and RV over 4-8 weeks time. A flexible, 5-spoke basket catheter bearing 25 electrode pairs was placed in the RA (n = 9) or the RV (n = 13) in 22 juvenile sheep (22-56 kg). The catheter was deployed for 0.1-4.1 hr (RA) and 0.3-3.9 hr (RV). In 20 of these 22 animals, 32 recordings were made of filtered (30-250 Hz) bipolar electrograms and surface ECG. Electrograms were timed and used to construct activation sequences based on a schematic of catheter geometry. Hearts were examined either acutely (4 RA and 9 RV studies) or 4-8 weeks after the procedure (5 RA and 4 RV studies). One animal undergoing RA placement had an air embolism resulting in cardiac arrest immediately prior to basket placement; all other animals were stable during placement. RA electrograms of sufficient quality to determine activation time were recorded from 82% of pairs in RA maps, and RV electrograms from 89% of pairs in RV maps. Mean activation sequence duration in RV was 16 ms versus 47 ms in RA (P < 0.0001), making construction of RV maps more difficult. Acute postmortem studies of RV placement revealed a silent apical RV puncture in one animal. Superficial abrasion or ecchymosis of RV endocardium and/or tricuspid valve were noted in six animals. Postmortem exams in both RA and RV chronic studies showed healed endocardial lesions, with only superficial scarring. Rapid RV activation mapping using a basket catheter is feasible, but requires precision recording techniques. Endocardial abrasions produced in lambs both by RA and RV placement of the catheter are healed in < 4-8 weeks, with trivial residua. The multielectrode basket catheter may be applicable to the mapping of tachycardias originating in or involving the right ventricle.

High-density endocardial activation mapping of the right atrium in three dimensions by composition of multielectrode catheter recordings

The use of radiofrequency ablation for treatment of complex arrhythmia substrates has prompted interest in transcatheter endocardial activation mapping. Technical constraints on catheter fabrication and the intention to use such maps to guide ablation both demand innovative approaches to mapping. A fluoroscopically based endocardial mapping technique is proposed to improve the ability of electrophysiologists to interpret large amounts of data acquired using multielectrode catheter arrays, improving their ability to visualize the data and act on its content. This technique addresses previous limitations imposed by the number of electrodes that can be deployed and by the difficulty in determining their relative spatial locations. It is based on the composition of multiple activation sequence mappings made in a single rhythm, with the spatial locations of recording electrode pairs determined in orthogonal fluoroscopic views referenced to stable intrathoracic markers. Rather than imposing a geometry determined primarily by the measurement apparatus, the spatial locations of only those electrodes in proximity to the endocardial surface, as determined by their ability to record bipolar electrograms, are measured. In this manner, the geometry of the endocardium may be approximated by measurements made of electrode position. Using this approach, the number of endocardial sites that can be sampled in a stable rhythm is theoretically unlimited, resulting in the realization of high-resolution activation maps. Spatiotemporal data may be used to create three-dimensional activation sequence maps, displayed as animated sequences. This technique was used in anatomically normal and diseased human right atria to create activation maps of sinus and paced rhythms, classic atrial flutter, and postoperative intraatrial reentrant tachycardia, using a median of 108 electrode positions (range, 27-197) in 25 maps. The activation sequences represented by these maps were diverse, but qualitatively concordant with known mechanisms of atrial activation. High-density catheter-based activation mapping of the right atrium is feasible and may improve understanding of complex arrhythmias and assist in the development of ablative techniques. Further research is needed on the spatial correlation between cardiac anatomy and fluorography, suppression of spatial artifact, and optimal mapping densities.

In-hospital mortality for surgical repair of congenital heart defects: preliminary observations of variation by hospital caseload

OBJECTIVE

To examine the impact of hospital caseload on in-hospital mortality for pediatric congenital heart surgery.

DESIGN

Population-based, retrospective cohort study.

SETTING

Acute care hospitals in California and Massachusetts.

PATIENTS

Children undergoing surgery for congenital heart disease, identified by the presence of procedure codes indicating surgical repair of a congenital heart defect in computerized statewide hospital discharge abstract databases. Cases were grouped into four categories based on the complexity of the procedure.

MAIN OUTCOME MEASURES

Adjusted odds ratios (OR) for in-hospital death were estimated using generalized estimating equations that account for the intra-institutional correlation among patients.

RESULTS

A total of 2833 cases at 37 centers were identified. Compared with centers performing > 300 cases per year, after controlling for patient characteristics, centers performing < 10 cases per year had an OR for in-hospital death of 7.7 (95% confidence interval (CI) [1.6-37.8]); 10 to 100 cases, OR = 2.9 (95% CI [1.6-5.3]); 101 to 300 cases, OR = 3.0 (95% CI [1.8-4.9]). Independent risk factors for mortality included procedure complexity category (P < .0001), use of cardiopulmonary bypass (P < .0001), young age at surgery (P = .001), and transfer from another acute care hospital (P < .0001). Few differences were found by hospital caseload in length of stay or total hospital charges.

CONCLUSIONS

For children with a congenital heart defect who underwent surgery in California in 1988 or Massachusetts in 1989, the risk of dying in-hospital was much lower if the surgery was performed at an institution performing > 300 cases annually. This study was limited by the absence of clinical detail in discharge abstract databases. If these findings are corroborated by other studies, health care delivery strategies that direct children requiring surgical correction of congenital heart defects to high-volume centers may substantially reduce overall mortality.

Influence of right heart size on outcome in pulmonary atresia with intact ventricular septum

BACKGROUND

Neonates with pulmonary atresia and intact ventricular septum (PA-IVS) are frequently born with hypoplastic right heart structures that must grow after right ventricular decompression (RVD) procedures for a complete two-ventricle physiology to be achieved. Previous authors have asserted that neonatal right heart size or morphology will predict right heart growth potential. Since 1983, our bias has favored early RVD regardless of initial right heart size. In 1986, we recognized a subset of patients with coronary artery abnormalities associated with poor outcome after RVD and have defined these patients as having a right ventricular-dependent coronary circulation (RVDCC).

METHODS AND RESULTS

To assess the influence of right heart size on outcome independent of the presence of RVDCC, we measured echocardiographic right ventricular (RV) dimensions in 37 neonates with adequate studies presenting between 1983 and 1990. Coronary artery anatomy was adequately assessed by angiography in 36. RV volume and tricuspid valve (TV) diameter were significantly smaller in patients with RVDCC than in those without. However, there was no statistically significant association between RV volume or TV diameter and survival among patients with or without RVDCC: Among 29 patients without RVDCC, 23 of 24 (95.8%) who achieved RVD are alive compared with 1 of 5 (20%) who did not achieve RVD (P = .001). Twenty-one of the 23 survivors have a complete two-ventricle physiology with low right atrial pressure. Among 7 patients with RVDCC, 2 patients who underwent RVD died early of left ventricular failure, whereas 4 of 5 who did not undergo RVD have survived single ventricular palliation.

CONCLUSIONS

Small right heart size is associated with RVDCC but is not associated with survival in PA-IVS. Patients without RVDCC have improved survival after RVD regardless of neonatal right heart size.

Multipolar endocardial mapping of the right atrium during cardiac catheterization: description of a new technique

OBJECTIVES

Using a new mapping system that allows the simultaneous acquisition of data from 25 right atrial bipolar electrodes during cardiac catheterization, we mapped normal sinus rhythm and atrial reentrant tachycardia in 24 sheep (20 to 49 kg) and 7 pigs (25 to 35 kg).

BACKGROUND

Rapid, high resolution mapping during cardiac catheterization may shorten ablation procedures and permit ablation of otherwise refractory arrhythmias.

METHODS

A flexible, elliptic, basket-shaped recording catheter has five spokes, each with 10 electrodes arranged as 5 bipolar pairs. Catheter shape, electrode spacing and introduction technique were modified in response to the results of experiments in the first 23 animals. In the most recent eight animals, retraction of a string attached to the distal tip distended the basket, providing safe tissue contact. Filtered (30 to 250 Hz) bipolar recordings from all 25 electrode pairs, as well as a surface electrocardiogram, were recorded and digitized at 1,000 Hz using custom software. An activation map was digitally constructed and superimposed on anteroposterior and lateral fluoroscopic catheter images. Bipolar recordings were made in normal sinus rhythm (31 animals), with adequate signals recorded from > 95% of electrode pairs. Rapid burst pacing and intentional right atrial air embolus (30 to 50 ml) induced sustained atrial reentrant tachycardia in five animals, which was also adequately recorded.

RESULTS

Catheter positioning and complete atrial mapping required < 10 min after venous access in the most recent eight experiments. The catheter was left in position for up to 4 h. Postmortem evaluation revealed minor superficial abrasion of the venae cavae or right atrial endocardium in six animals and moderate abrasion in two. No other damage was observed.

CONCLUSIONS

This new system may ultimately assist in mapping simple or complex atrial arrhythmias during cardiac catheterization.

Individual pulmonary vein size and survival in infants with totally anomalous pulmonary venous connection

OBJECTIVES

We investigated whether mortality in totally anomalous pulmonary venous connection could be predicted from preoperative individual pulmonary vein size.

BACKGROUND

Some infants with this anomaly die with or without surgical repair because of stenosis of individual pulmonary veins.

METHODS

Individual pulmonary vein, vertical vein and pulmonary venous confluence diameters were retrospectively measured from preoperative echocardiograms in 32 infants with totally anomalous pulmonary venous connection presenting to Children's Hospital, Boston over a 4 1/2-year period. Data on body surface area, other cardiac anomalies, presence of initial pulmonary venous obstruction and early surgery and outcome were also recorded.

RESULTS

Of 32 patients, 6 (18.8%) died before hospital discharge, and 8 (25.0%) died subsequently. Six (75.0%) of the eight patients who died late had individual pulmonary vein stenosis at sites remote from the surgical anastomosis to the left atrium. The remaining 18 patients (56.3%) are alive at a mean follow-up period of 9.7 months. A Cox proportional hazards model revealed that small sum of individual pulmonary vein diameters (p = 0.0004), small confluence size (p = 0.02) and presence of heterotaxy syndrome (p = 0.008) were each significant univariate predictors of survival. Multivariate analysis showed that small pulmonary vein sum was a strong predictor of survival (p = 0.008), independent of the presence of heterotaxy syndrome. An analysis stratified by the presence of heterotaxy syndrome showed that the predictive effect of small pulmonary vein sum on survival was strongest in patients without heterotaxy syndrome.

CONCLUSIONS

These data show that individual pulmonary vein size at diagnosis is a strong, independent predictor of survival in patients with totally anomalous pulmonary venous connection. In patients with this anomaly and small individual pulmonary veins, the anomaly may not be correctable by surgical creation of an anastomosis between the pulmonary venous confluence and the left atrium.

Research note: efficacy of various flavonoids and simple phenolics in prevention of nutritional myopathy in the chick

A 33-day feeding experiment was conducted with 3-day-old broiler chicks to assess the efficacy of various flavonoid and simple phenolic antioxidants in preventing nutritional muscular dystrophy (NMD) resulting from vitamin E deficiency. None of the flavonoids or simple phenolics at a dietary concentration of 1,000 ppm completely prevented NMD but quercetin reduced (P less than .05) its incidence and quercetin, morin, and ferulic acid reduced (P less than .05) the severity of the disorder. The low-selenium, low-vitamin E diet also promoted the development of a mild exudative diathesis (ED) in many of the birds, which was inhibited (P less than .05) by the rutin and silymarin treatments, but exacerbated (P less than .05) by quercetin, morin, and ferulic acid. Changes in concentrations of vitamin E in plasma, liver, or muscle, caused by the various treatments (other than vitamin E), were not related to protection against NMD or ED.

Changes in lipid composition of calf tissues by excess dietary zinc

In a previous study, very high Zn (1000 ppm) prevented most of the tissue lipid increases caused by very high Cu (1000 ppm), and this investigation was conducted to study whether Zn had a direct effect on lipid metabolism or simply acted indirectly by inhibiting excess Cu activity. Calves were fed basal dietary Cu (10 ppm), and lipid composition of heart, liver, and blood plasma was measured as affected by control (40 ppm in DM), high (500 ppm), or very high (1000 pm) Zn intakes. Supplementation with 1000 ppm of Zn did not cause any marked quantitative changes in tissue lipids (e.g., lipid classes, oleic, or stearic acids), suggesting that, in the previous study, Zn had mainly interfered with excess Cu effects on lipids rather than with lipid metabolism directly. However, there were two exceptions. Adding 1000 ppm of Zn to basal Cu ration 1) reduced concentration and changed the fatty acid composition of plasma cholesterol esters, both of which are indicative of excess Zn inhibiting lecithin:cholesterol acyltransferase activity, and 2) altered the desaturation and elongation of the essential fatty acids and their concentration in tissue phospholipids. This latter effect of excess Zn conceivably could be important in changing the structure and function of cell membranes and in the production and activity of prostanoids and leukotrienes.

Function of the anatomic pulmonary valve in the systemic circulation

The anatomic pulmonary valve, which has thin leaflets with little elastic tissue in the normal heart, must function as the neoaortic valve after arterial switch operation (ASO) for transposition of the great arteries, palliative surgery for hypoplastic left heart syndrome (HLHS), and pulmonary artery-to-aortic (P-A) anastomosis for complex heart disease with subaortic obstruction. The long-term function of this valve under these circumstances is not known. To investigate the function of this valve in the systemic circulation, the follow-up echocardiograms, catheterization data, and angiograms were reviewed for 189 patients at our institution after an ASO (n = 112), palliative surgery for HLHS (n = 45), or P-A anastomosis (n = 32). In addition, the effect on valve function of preoperative anatomy, prior placement of a pulmonary artery band (PAB), and length of follow-up was examined. Neoaortic regurgitation was present in 41% of patients after an ASO (mean +/- SD) follow-up (20 +/- 20; range, 2.2-80.5 months), 60% of patients after an HLHS repair (21 +/- 15; range, 3.7-62.4 months) and 50% after a P-A anastomosis (27 +/- 21; range, 2.6-89.4 months). Only eight patients had more than trivial/mild regurgitation. No neoaortic stenosis was observed. Minor preoperative valve abnormalities did not influence postoperative valve function. Prior PAB placement significantly increased the likelihood of postoperative neoaortic regurgitation after a two-stage ASO but not after a P-A anastomosis. In the ASO group, patients with an intact ventricular septum had a significantly higher prevalence of neoaortic regurgitation than those with a ventricular septal defect.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of excess dietary manganese on lipid composition of calf blood plasma, heart, and liver

Preruminant calves were fed milk replacer containing control (40 ppm) or two high concentrations (200 and 1000 ppm) of Mn to assess the effect of excessive Mn intakes on plasma, heart, and liver lipids. The two higher Mn intakes had no effect on lipid classes in liver and heart, except for elevated triglycerides in liver and lower sphingomyelin in heart (for 1000 ppm of Mn). At 1000 ppm of Mn intake, but not at 200 ppm, marked increases occurred in plasma total lipids, phosphatidylcholine, cholesterol, cholesterol esters, sphingomyelin, and triglycerides. The highest intake altered the essential fatty acid composition of liver phosphatidylcholine. Linoleic and linolenic acids were increased, but arachidonic and eicosapentaenoic acids were decreased, suggesting that very high excess of Mn interfered with hepatic desaturation and elongation of the essential fatty acids. Thus, high Mn intake (200 ppm) caused relatively few tissue lipid changes, whereas very high intake (1000 ppm) markedly increased plasma lipid classes and apparently interfered with essential fatty acid metabolism in liver.

Tolerance of the preruminant calf for excess manganese or zinc in milk replacer

In two experiments, calves were fed milk replacer containing 40, 200, 500, 1000, or 5000 ppm Mn or 40, 200, 500, 700, or 1000 ppm Zn in DM, from 3 to 38 d of age, to estimate the minimum toxic concentrations of Mn and Zn. Starting at 1000 ppm Mn, weight gains and feed efficiencies were decreased slightly; none of the calves fed 5000 ppm Mn survived the 5-wk experiment. Liver and bile showed the largest increases in Mn concentration. In the Zn experiment, only at 700 and 1000 ppm Zn were weight gains, DM intake, and feed efficiency reduced. Largest Zn increases were in liver, kidney, and plasma. Thus, performance of the preruminant calves was not affected adversely by 500 ppm Mn or 500 ppm Zn in milk replacer, concentrations that are markedly higher than the NRC recommendations of 40 ppm Mn and 40 ppm Zn. However, Mn and Zn concentrations increased in some tissues, and toxicities might have arisen if the trial had been continued. Evidence was not obtained indicating that the calf benefits from Mn or Zn intakes above the NRC recommendations.

Effects of dietary corn oil and fish oil concentrate on lipid composition of calf tissues

Lipid composition of calf blood plasma, liver platelets, muscle, heart, and brain was measured, as affected by high dietary intake of linoleic acid from corn oil or of polyunsaturated fatty acids from fish oil concentrate. Plasma total lipids, phosphatidylcholine, and cholesteryl esters were reduced by corn oil and fish oil concentrate. Dietary fatty acid composition had no influence on percentage distribution of the major phospholipid components of liver, heart, muscle, and brain, but did alter the polyunsaturated fatty acid composition of major phospholipids in plasma, liver, platelets, muscle, and heart. In general, high linoleic acid intake increased linoleic acid and decreased oleic, arachidonic, and linolenic acids in tissue phospholipids, and fish oil concentrate high in eicosapentaenoic and docosahexaenoic acids increased phospholipid concentrations of these fatty acids. The fatty acid composition of brain phosphatidylcholine and phosphatidyl-ethanolamine was relatively resistant to dietary lipid alterations. The fatty acid changes in tissue phospholipids that resulted from dietary lipid alterations may have important implications in eicosanoid metabolism, and in the structure and function of cell membranes.

Lipid compositional changes in calves fed excess iodine

Calves were fed milk replacer containing .57, 10, or 200 ppm iodine (from ethylenediaminedihydriodide) to determine the effects of excess dietary iodine on composition of lipids in blood plasma, liver, and heart. High iodine intakes had no effect on plasma total lipids or lipid classes, but caused lipid class concentration changes in liver and heart. Both 10 and 200 ppm iodine increased concentration of liver phosphatidylethanolamine and heart phosphatidylcholine, cholesterol, and total lipids, and the 200 ppm intake also increased concentration of liver phosphatidylcholine, total lipids, and heart phosphatidylethanolamine. Both iodine treatments tended to increase all the other minor lipid classes in liver and heart as well. Both 10 and 200 ppm iodine treatments increased some of the n-3 polyunsaturated fatty acids in the major phospholipids of plasma, liver, and heart. For the preruminant calf, liver and heart may be more useful than blood plasma for indicating excess iodine effects on lipid metabolism.

Effects of elevated iodine in milk replacer on calf performance

Calves were fed milk replacer containing .57, 10, 50, 100, or 200 ppm iodine (from ethylenediaminedihydroiodide) in DM, from 3 to 38 d of age, to estimate the minimum toxic concentration of iodine. Only the 200 ppm iodine intake reduced weight gains, DM intake, feed efficiency, and DM digestibility. At the 100 and 200 ppm iodine intakes, protein digestibility was reduced, and calves showed typical symptoms of iodine toxicity (nasal discharge, excessive tear and saliva formation, and coughing from tracheal congestion). Thyroid iodine increased with every elevation in iodine intake. Iodine in plasma, bile, and non-thyroid tissues started to increase at the 50 ppm intake and, except for muscle, tended to increase again at the 100 and 200 ppm intakes. Thus, the preruminant calf tolerated up to 50 ppm iodine in milk replacer DM for 5 wk postpartum. However, as iodine concentrations in plasma and nonthyroid tissues started to increase at 50 ppm iodine, an upper limit of 10 ppm would be more preferable.

Influence of excess dietary copper on lipid composition of calf tissues

Lipid composition of calf liver, heart, and skeletal muscle was measured, as affected by control Cu (10 ppm in DM), high Cu (1000 ppm), or high Cu plus high Zn (1000 ppm) in milk replacer. High dietary Cu increased all lipid classes in liver, some in the heart, and decreased all lipid classes except cholesterol in muscle. Zinc inhibited many of the changes in tissue lipid classes by excess copper. High Cu intake increased fatty acid unsaturation (palmitoleic, oleic, linoleic acids) and decreased stearic acid in phosphatidylcholine and phosphatidylethanolamine of liver and heart. Excess Cu tended to have an opposite effect in changing fatty acid concentrations in liver and muscle. Activities of various desaturases and elongases were estimated in liver, heart, and muscle using ratios of fatty acid precursors to products in combined phosphatidylcholine and phosphatidylethanolamine. High Cu intake frequently altered activities of these enzymes in all three tissues with additional high Zn usually coregulating activity in the direction opposite to Cu.

Effect of copper loading of preruminant calves on intracellular distribution of hepatic copper, zinc, iron, and molybdenum

The subcellular distribution of Cu, Zn, Fe, and Mo was investigated in liver homogenates from preruminant calves fed control Cu (10 ppm), high Cu (1000 ppm), or high Cu plus high Zn (1000 ppm) milk replacer. For controls, Cu was located primarily in the nuclei and large granule fractions, Zn mainly in the cytosol, and Fe in the cytosol and nuclei fraction; Mo was present in all compartments but least in microsomes. Calves fed high Cu had markedly increased hepatic Cu concentration in the nuclei and cytosol fractions, reduced cytosol Zn, increased nuclei Fe, and decreased Mo concentration in all cell compartments. Feeding high Zn with high Cu (which prevented deaths from high Cu) reversed some changes in hepatic trace element patterns caused by high Cu while initiating new alterations. The marked increase in hepatic Cu and reduced Mo in nuclei and cytosol after Cu loading indicate that these compartments may have a predominant role in the development of Cu toxicity in the preruminant calf.

Tolerance of the calf for excess copper in milk replacer

Calves were fed milk replacer containing 10, 50, 200, 500, or 1000 ppm Cu, from 3 d to 45 d of age, to estimate the Cu concentration that would adversely affect calf performance. Weight gains and feed efficiency were similar for 10 and 50 ppm Cu but were reduced at 200 and 500 ppm Cu. All calves survived 500 ppm Cu and lower intakes, but only 4 of 7 calves survived the 1000 ppm concentration. Typical clinical symptoms of chronic Cu toxicity and hemolytic crisis were evident for the 1000 ppm calves before death. Additional 1000 ppm Zn prevented deaths for 1000 ppm Cu, but calf performance was poor. Increased Cu intakes elevated plasma ceruloplasmin and glutamic oxalacetic transaminase activity, reduced packed cell volume (hematocrit), markedly increased fecal excretion of Mo and Zn, increased Cu concentration of liver, muscle, heart, blood, and bile, and decreased Mo and Zn in liver. We found 50 ppm Cu a safe intake where milk replacer contained 48 ppm Zn and 1.1 ppm Mo. However, at lower intakes of these elements, and for longer feeding periods than 6 wk, the calf may be much more susceptible to Cu toxicity.

Plasma lipoproteins in neonatal, preruminant, and weaned calf

This study compared plasma lipoprotein fraction profiles and lipid composition in the calf at 3 d, 3 wk, and 12 wk (weaned). For all ages the major plasma lipoprotein fraction was high density lipoproteins (52 to 73%), followed by very high density lipoproteins (10 to 22%), low density lipoproteins (13 to 18%), and chylomicrons plus very low density lipoproteins (5 to 9%). Most plasma lipid was cholesterol esters (41 to 49%) and phosphatidylcholine (21 to 29%). Most cholesterol esters (66 to 81%) and phosphatidylcholine (68 to 80%) were in high density lipoproteins; free fatty acids (83 to 96%) and lysophosphatidylcholine (75 to 85%) in very high density lipoproteins; and triglycerides (93 to 98%) in the remaining lipoprotein fractions. Of the three ages studied, 3-d-old calves had comparatively low plasma total lipids, high density lipoproteins, cholesterol esters, phosphatidylcholine, and linoleic acid in all lipid classes; they had relatively high plasma very high density lipoproteins, triglycerides, free fatty acids, phosphatidylethanolamine, and 20:3 n-9 fatty acid (indicative of essential fatty acids deficiency). Lipoprotein classes and lipid composition were similar at wk 3 and 12. Comparison of fatty acid profiles for phosphatidylcholine with those for lysophosphatidylcholine and cholesterol esters indicated plasma lecithin-cholesterol acyltransferase was active in calves at all three ages studied.

Factors affecting poor performance and scours in preruminant calves fed corn oil

A 4-wk study with 12 3-d-old calves compared the effect of feeding tallow, corn oil, or corn oil plus aspirin on calf performance, feed utilization, incidence of scours, and composition of blood plasma lipids. Aspirin treatment was to inhibit a possible role of prostaglandins in promoting scours. Calves given both corn oil treatments had lower average daily gain, feed efficiency, and higher incidence of scours than those fed tallow. Unexpectedly, corn oil produced appreciably less scours in calves than encountered in previous studies. This appeared to be related to the fat dispersion method used here, which produced much smaller fat globules (less than 1 micron vs. 10 to 20 microns). Over-production of prostaglandins from corn oil was not a causative factor in scours development. Arachidonic acid and other linoleic acid prostaglandin precursors in blood plasma cholesteryl esters and phosphatidylcholine were reduced by dietary corn oil. Aspirin, a potent inhibitor of prostaglandin biosynthesis, was ineffective in reducing scours.

Binding of selenium-75 to blood and liver cytosolic proteins in the preruminant calf

Labeled selenite (75Se) administered to calves in milk replacer, containing .2 or 5 ppm Se, was rapidly absorbed with peak blood 75Se at 6 h. Gel filtration and dialysis treatment of plasma and erythrocyte hemolysates showed that initially 75Se was transported in blood as 75SeO3= or loosely bound to plasma and erythrocyte proteins. At high Se intake, albumin became a transport protein for some of the plasma 75Se, and proportionately more blood radioactivity was carried in the erythrocytes. At 72 h after dosing, most plasma 75Se was tightly bound to protein in glutathione peroxidase fraction with low peroxidase activity, possibly Se transport protein. At 72 h, distribution of 75Se in erythrocyte was 35 to 40% in glutathione peroxidase, 50% in hemoglobin, and 5% in a selenite plus selenopolypeptide fraction. Erythrocyte peroxidase activity was mostly in the glutathione peroxidase fraction (57%) and hemoglobin (38%). Molecular weight estimate for erythrocyte glutathione peroxidase was 84,200 daltons; about 90% of blood peroxidase activity was in erythrocytes. High Se intake had no marked effect on distribution of 75Se among liver cytosolic proteins. About 35% of 75Se was in glutathione peroxidase fraction, having most of the peroxidase activity, 25% in void volume, 11 to 18% in a selenite plus selenopolypeptide fraction, and small amounts in selenoproteins of about 12,000 and 50,000 daltons.

Effect of excess dietary iron on lipid composition of calf liver, heart, and skeletal muscle

Effect of excess dietary iron on lipid composition of calf liver, skeletal muscle, and heart was assessed. High dietary iron (5000 versus 100 ppm in milk replacer DM) had no effect on the relative proportion of lipid classes in liver or their unsaturated fatty acid composition. In muscle some minor lipid components were reduced and cholesterol and sphingomyelin increased. Excessive iron had a marked effect, however, on heart lipid composition, reducing total lipids and almost all lipid classes; triglycerides, sphingomyelin, and lysophosphatidylcholine were increased. Characteristically, sphingomyelin increases in cell membranes in response to aging and numerous pathological conditions. High dietary iron reduced linolenic acid in phosphatidyl-ethanolamine and phosphatidylcholine of both skeletal and cardiac muscle. This may have resulted from iron-caused ethane production from autoxidation of linolenic acid or other n-3 family fatty acids, an effect known to occur in the rat. Linoleic and arachidonic fatty acids appeared to be unaffected. Plasmalogens in muscle and heart phosphatidylethanolamine and phosphatidylcholine were increased by high iron intake. As these alk-1-enyl ethers protect cells from oxidation and radiation damage, their synthesis may have been increased in response to stress from excessive iron. The results indicate that a relatively high concentration of vitamin E may be required in calf milk replacer when excessive iron is present.

Effect of excess iron in milk replacer on calf performance

Milk replacers containing 100, 500, 1000, 2000, or 5000 ppm iron were fed to 3-d-old calves for 6 wk to estimate the lowest amount of dietary iron (added as ferrous sulfate) that would reduce calf performance. Calves tolerated all iron treatments except 5000 ppm. At this intake calves showed reduced weight gains, DM intake, feed efficiency, and digestibility of DM and protein. There were no other signs of iron toxicity and no gross abnormalities were found on postmortem examination. Percent of dietary iron in feces increased with higher dietary iron and ranged from 65 to 84%. Elevated iron intakes caused relatively small increases in iron concentration of blood plasma, bile, kidney, heart, and muscle but marked increased in spleen and liver iron, particularly in liver for the 2000 and 5000 ppm treatments. At 100 ppm iron intake, nonheme iron in liver, spleen, and kidney was composed of similar proportions of ferritin and hemosiderin, but at 5000 ppm iron intake, hemosiderin predominated in these tissues. Thus, the preruminant calf tolerated between 2000 and 5000 ppm iron in milk replacer. At toxic iron intake, calf performance and feed efficiency were reduced; there was a characteristic change to higher liver than spleen iron; and hemosiderin became the predominant iron storage compound in both tissues.

Performance of calves fed combinations of whole milk and reconstituted skim milk powder

A 52-d study with 24 3-d-old calves compared the effect of feeding whole milk (controls) or milk diluted 1:1 or 1:3 with reconstituted skim milk powder (10%, wt/wt) on calf performance to weaning at 38 d. Skim powder diets were supplemented with vitamins and trace minerals. Liquid diet was fed at 5% body weight twice daily for 24 d, then once daily for 14 d followed by abrupt weaning. Starter was provided for ad libitum intake from 14 to 52 d. For the first 13 d, controls had the greatest weight gains, but at 38 and 52 d, gains were similar for all groups. Three-quarters of the whole milk diet could be replaced with reconstituted skim milk powder (10% wt/wt) without any reduction in calf gain to weaning because starter intake increased 23%.