Jane Koleff

Twenty-four-hour ambulatory blood pressure monitoring detects a high prevalence of hypertension late after coarctation repair in patients with hypoplastic arches.

OBJECTIVES To determine by 24-hour blood pressure monitoring the risk of hypertension late after coarctation repair in patients with arch hypoplasia. METHODS Sixty-two of 116 consecutive patients (age, ≥10 years) who had coarctation repair and were quoted subjectively by the surgeon or the cardiologist to have arch hypoplasia at the time of the repair underwent a transthoracic echocardiogram and 24-hour blood pressure monitoring. Median age at repair was 11 days (range, 6-48 days). Mean preoperative z score of the proximal transverse arch was -2.43 ± 0.46. Eight patients had a repair via sternotomy (6 end-to-side anastomoses, 2 patch repairs) and 54 had a conventional repair via thoracotomy. RESULTS After a follow-up of 18 ± 5 years, 27% of the patients (17/62) had resting hypertension and 60% (37/62) had abnormal ambulatory blood pressure. Sensitivity of high resting blood pressure in detecting an abnormal 24-hour ambulatory blood pressure was 41%. Twenty patients had arch obstruction at last follow-up. Eighteen of them (90%) had abnormal ambulatory blood pressure. None of the patients operated on with end-to-side repair via sternotomy had reobstruction compared with 33% (18/54) of those repaired via thoracotomy. CONCLUSIONS Patients with a hypoplastic arch operated via thoracotomy have an alarming prevalence of hypertension. Regular follow-up with 24-hour ambulatory blood pressure monitoring is warranted, especially in patients who have had a smaller aortic arch at the time of the initial operation.

Tissue-specific splicing of an Ndufs6 gene-trap insertion generates a mitochondrial complex I deficiency-specific cardiomyopathy

Mitochondrial complex I (CI) deficiency is the most common mitochondrial enzyme defect in humans. Treatment of mitochondrial disorders is currently inadequate, emphasizing the need for experimental models. In humans, mutations in the NDUFS6 gene, encoding a CI subunit, cause severe CI deficiency and neonatal death. In this study, we generated a CI-deficient mouse model by knockdown of the Ndufs6 gene using a gene-trap embryonic stem cell line. Ndufs6gt/gt mice have essentially complete knockout of the Ndufs6 subunit in heart, resulting in marked CI deficiency. Small amounts of wild-type Ndufs6 mRNA are present in other tissues, apparently due to tissue-specific mRNA splicing, resulting in milder CI defects. Ndufs6gt/gt mice are born healthy, attain normal weight and maturity, and are fertile. However, after 4 mo in males and 8 mo in females, Ndufs6gt/gt mice are at increased risk of cardiac failure and death. Before overt heart failure, Ndufs6gt/gt hearts show decreased ATP synthesis, accumulation of hydroxyacylcarnitine, but not reactive oxygen species (ROS). Ndufs6gt/gt mice develop biventricular enlargement by 1 mo, most pronounced in males, with scattered fibrosis and abnormal mitochondrial but normal myofibrillar ultrastructure. Ndufs6gt/gt isolated working heart preparations show markedly reduced left ventricular systolic function, cardiac output, and functional work capacity. This reduced energetic and functional capacity is consistent with a known susceptibility of individuals with mitochondrial cardiomyopathy to metabolic crises precipitated by stresses. This model of CI deficiency will facilitate studies of pathogenesis, modifier genes, and testing of therapeutic approaches.

Favourable anatomy after end-to-side repair of interrupted aortic arch.

OBJECTIVE To evaluate cardiovascular outcomes in patients with aortic arch repair and their possible correlation with arch geometry. METHODS Ten patients who underwent end-to-side repair for aortic arch interruption (IAA), older than 10 years were compared to a cohort of 10 post coarctation (CoA) repair patients matched for age, sex and age at repair. Mean age at operation was 9.7±6.5 days. Patients underwent a resting and 24 h blood pressure measurements, exercise study, MRI, transthoracic echocardiography and vascular studies. RESULTS Seven patients developed hypertension, two from IAA group and five from CoA group. Nine patients (45%) had gothic arch geometry, three from IAA group and six from CoA group. Despite differences in arch geometry, both groups had normal LV mass, LV function and vascular function. CONCLUSION No differences in functional or morphologic outcomes could be demonstrated between the end-to-side repair of the arch by sternotomy and the conventional coarctation repair by thoracotomy. A favourable arch geometry can be achieved after the end-to-side repair of the aortic arch. In the present study, we could not correlate adverse arch geometry with any adverse cardio-vascular outcomes. After neonatal arch repair, the contributive role of aortic arch geometry to late hypertension remains uncertain.

Impact of arch reobstruction and early hypertension on late hypertension after coarctation repair

OBJECTIVES Late hypertension after coarctation repair is associated with high mortality, but its risk factors remain unclear. This study aims to determine early and late postoperative risk factors for late hypertension after coarctation repair. METHODS A cross-sectional study including transthoracic echocardiogram and 24-h blood pressure (BP) monitoring was performed in 144 patients aged ≥10 years with previous coarctation repair. Median age at repair was 39 days (interquartile range 0-3 years). Early postoperative hypertension was evaluated by calculating the mean of BP measurements taken on the same day before hospital discharge or the need for antihypertensives prior to discharge. Multivariable analyses were performed to adjust for gender, surgical age, and follow-up age. RESULTS After a mean follow-up period of 22 ± 7 years, 59% (84/142) of patients were hypertensive: 58% (82/142) on 24-h BP monitoring and 1% (2/142) on antihypertensives. Early postoperative hypertension was present in 58% (73/126): 39% (49/126) on BP measurements and 19% (24/126) on antihypertensives. Early and late arch reobstruction (transthoracic echocardiogram peak gradient ≥25 mmHg) was present in 37% (23/62) and 23% (33/144), respectively. On multivariable logistic analysis, early postoperative hypertension and maximum descending arch velocity on echocardiography were associated with late hypertension on 24-h BP monitoring (odds ratio 2.21, 95% confidence interval 1.05-4.66, P = 0.04; and odds ratio 2.28, 95% confidence interval 1.08-4.81, P = 0.03; respectively). CONCLUSIONS There is a high prevalence of late hypertension after coarctation repair. Arch reobstruction may be a major determinant of late hypertension. Early postoperative hypertension may identify very early in life those at risk of developing late hypertension.

A Cross-Sectional Study of the Prevalence of Exercise-Induced Hypertension in Childhood Following Repair of Coarctation of the Aorta

BACKGROUND Exercise-testing may be a more tolerable method of detecting hypertension in children after coarctation repair compared to gold-standard 24-hour ambulatory blood pressure (BP) monitoring (ABPM). This study aims to determine the prevalence of exercise-induced hypertension and end-organ damage in children after coarctation repair, and the effectiveness of exercise-testing compared to 24-hour ABPM in this population. METHODS Exercise-testing (Bruce protocol), transthoracic echocardiogram, 24-hour ABPM, and pulse wave velocity were performed in 41 patients aged 8 to 18 years with previous coarctation repair. Median age at repair was 13 days. Exercise-testing data were compared to healthy paediatric controls. Hypertension was defined as BP >95th percentile on 24-hour ABPM compared to normalised data, and systolic BP (SBP) arbitrarily >200mmHg on exercise-testing. RESULTS After 13±3years, 39% (14/36) were hypertensive on 24-hour ABPM and 12% (5/41) on exercise-testing. Coarctation patients had a higher peak exercise SBP and reduced endurance compared to controls (164±26mmHg vs. 148±19mmHg, p=0.003; and 13.0±1.7mins vs. 14.2±2.4mins, p=0.007; respectively). All patients with a peak exercise SBP >190mmHg were hypertensive on 24-hour ABPM. Pulse wave velocity was higher in hypertensive patients on exercise-testing and 24-hour ABPM compared to normotensive patients (p=0.004 and p=0.06; respectively). CONCLUSIONS Exercise-testing may be a useful tool to detect hypertension in children and young adults after coarctation repair, particularly in those who do not tolerate 24-hour ABPM. Normative peak exercise BP data for age should be obtained to improve the accuracy of exercise-testing in detecting hypertension.