PubMed Health⌕ Search

Biomedical subjects

M K Lenk

Publications and source records attributed to M K Lenk.

15 recordsLinked to original sources

Efficacy and safety of rectal thiopental sedation in outpatient echocardiographic examination of children.

UNLABELLED: The efficacy and safety of rectal thiopental administration in sedation for paediatric echocardiographic examination were prospectively investigated in infants with known or suspected congenital heart disease in an outpatient manner. A total of 1150 patients (546F, 604M) were studied; 264 were 7 d to 6 mo old (group I), 572 were 6 mo to 2-y-old (group II), and 314 were 2 to 6-y-old (group III). Thiopental sodium dissolved in 10 ml of water in a syringe to which a 6-F feeding catheter was attached was administered prior to echocardiographic examination to patients in groups I, II and III with doses of 50, 35 and 25 mg/kg, respectively in an emergency care environment. Length of time to achieve sedation (induction time), duration of sedation, length of time to return to normal activity (recovery time), whether sedation was successful and side effects were recorded. In the overall study population, sedation was successful in 1094 (95.1%) of the patients, the induction time was 16.34 +/- 3.69 min, the duration of sedation was 35.07 +/- 7.04 min, the recovery time was 63.25 +/- 10.17 min and the overall side-effect prevalence was 2%. Sedation was significantly more successful, the induction time was significantly shorter, the recovery time was significantly longer and side effects significantly more prominent in groups I and II compared to group III. CONCLUSION: Rectally administered thiopental is a safe and efficacious agent for sedation of infants and young children with known or suspected congenital heart disease who are undergoing echocardiography in an outpatient cardiology clinic, provided that it is used in an emergency care setting considering the risk of respiratory depression even though the prevalence of this side effect is significantly low.

Administration, Rectal↗

Auditory brainstem responses in children with congenital heart disease.

BACKGROUND: Cyanotic congenital heart diseases usually lead to growth and developmental delay in children due to chronic hypoxemia and undernourishment that may affect the central nervous system. The auditory brainstem responses are determined to assess the maturation and function of the brainstem. Therefore, we used the auditory brainstem responses to investigate the effect of cyanotic congenital heart diseases on brainstem maturation. METHODS: The auditory brainstem responses were investigated in 45 children (23 cyanotic, 22 acyanotic) with congenital heart diseases and compared with the results of 30 healthy counterparts (all children were aged between 2 months and 15 years). RESULTS: The results of auditory brainstem responses were similar in acyanotic patients and in normal children. The cyanotic patients under 1 year of age had more prolonged I-V interpeak latencies than those of control and acyanotic patients (P < 0.05). There was no difference between all groups older than 1 year of age. In cyanotic children, I-V interpeak latencies showed significant negative correlation with arterial oxygen saturation and partial oxygen pressure (P < 0.05). CONCLUSIONS: Cyanotic congenital heart diseases may cause significant retardation on brainstem maturation due to chronic hypoxemia, especially in infants under 1 year of age, whereas acyanotic congenital heart diseases have no effect on auditory brainstem responses.

Adolescent↗

Comparison of normal sinus rhythm and pacing rate in children with minute ventilation single chamber rate adaptive permanent pacemakers.

Rate adaptive pacemakers are used to achieve a better cardiac performance during exercise by increasing the heart rate and cardiac output. The ideal rate adaptive sensor should be able to mimic sinus node modulation under various degrees of exercise and other metabolic needs. Minute ventilation sensing has proven to be one of the most accurate sensor systems. In this study, alterations in sinus rhythm and pacing rates during daily life conditions in 11 children (median age 11 years, range 6-14 years) with minute ventilation single chamber pacemakers were investigated. Correlation of sinus rhythm with pacing rates was assessed. ECG records were obtained from 24-hour Holter monitoring. Average rates of five consecutive P waves and pace waves were determined every half hour. The average of the two values was then used to determine hourly rates. Correlation coefficients between the sinus rhythm and pacing rates were calculated. In nine patients, pacing rates correlated well to sinus rhythm (range 0.6793-0.9558, P < 0.001 and P < 0.05), whereas in two cases correlation was not sufficient (P > 0.05). Most of the patients, in whom rate response factor (RRF) measurements during peak exercise by treadmill with chronotropic assessment exercise protocol were performed and pacemakers were programmed to these parameters, had more appropriate ventricular rates compared to spontaneous sinus rates. In these patients mean RRF value was 15.3 +/- 2.7 (range 12-20, median 15). This study shows that during daily activities minute ventilation rate adaptive pacemakers can achieve pacing rates well correlated to sinus rhythm that reflects the physiological heart rate in children.

Activities of Daily Living↗

Dual sensor pacemakers in children: what is the choice of sensor blending?

UNLABELLED: Dual sensor pacemakers were developed to obtain more appropriate responses to activity. We evaluated ten children with dual sensor pacemakers in different sensor blending circumstances using exercise testing to assess which ratio was optimal. Ten patients with several bradydysrhythmias (ages 6-16 years; mean 10.1 years) were included in the study. Eight patients had VVIR pacemakers (Vitatron Topaz), models and two patients had VDD pacemakers implanted via the transvenous route. All patients were in a paced rhythm (98.5% pacing). Accurate T wave sensing ranged from 81%-100%; mean 92%, median 95%. Voluntary exercise testing with a CAEP protocol was performed using a treadmill with the pacemaker in VVIR mode. Medium activity threshold with three sensor blending ratios (QT = ACT, QT > ACT, and QT < ACT) were done in all patients. The mean duration of exercise was not statistically different among the three sensor blending ratios. After 90 seconds of exercise, the mean pacing rate had increased by 12%, 3%, and 5%, respectively, in the three groups. At maximal exercise, the increases were 45%, 42%, and 54%. Mean HRs during exercise in each of the three ratios were not significantly different, although we found a statistically significant increase in HR during the first two stages of rest period in the QT = ACT sensor blending ratio compared to the QT > ACT ratio. No difference was observed after the second stage. IN CONCLUSION: (1) there is no difference between the QT = ACT, QT < ACT, and QT > ACT sensor blending ratios; and (2) each child has to be evaluated by exercise testing to program a correct sensor blending ratio.

Adolescent↗

Initial experience with dual-sensor rate-responsive pacemakers in children.

The efficacy of a new single-chamber, rate-responsive pacemaker that utilizes information from two sensors, activity and stimulus to T wave, was evaluated in 15 children during a mean follow-up period of 10.3 +/- 3.3 months (range 5-16 months). There were 10 males and five females, with a mean age of 5.9 +/- 3.8 years (range 9 months-16 years). The indication for pacing was high grade atrioventricular block in 10 (eight postoperative, two congenital), and sinus node dysfunction in five patients. In endocardial implants the mean T wave amplitude was 2.48 +/- 0.7 mV, and mean T wave sensing 91 +/- 6.3%, whereas in epicardial implants T wave amplitude and sensing were inadequate. Each patient underwent 24-h Holter monitoring and 10 performed a graded treadmill test in three sensor-blending modes (Stimulus-T = Activity, Stimulus-T > Activity, Stimulus-T < Activity), using the chronotropic assessment exercise protocol. Sensor cross-checking was analysed by continuous tapping over the pacemaker. Holter monitoring demonstrated that pacing rate variations were closely related to daily activity. At the initial phases of exercise testing, the mean percentage of increase in pacing rate was significantly lower in Stimulus-T > Activity mode, when compared to Stimulus-T = Activity (P < 0.01); however, the initial disparity among the three modes disappeared halfway through the exercise and similar heart rate changes were observed thereafter. Continuous tapping over the pacemaker in Stimulus-T = Activity mode caused an initial increase in pacing rate, and inappropriate responses were quickly corrected by sensor cross-checking. Rate modulation with a single-chamber, dual-sensor pacemaker is adequate and safe in children, and may offer significant advantages over single-sensor devices in endocardial implants.

Adolescent↗

Severe intrauterine growth retardation, aged facial appearance, and congenital heart disease in a newborn with Johanson-Blizzard syndrome.

We report a female newborn with Johanson-Blizzard syndrome associated with extreme intrauterine growth retardation, aged facial appearance, and atrial septal defect. Other features are microcephaly, prominent veins over the scalp, alopecia over the vertex, wide-open fontanelle, high forehead, antimongoloid slant, edematous eyelids, the absence of eyebrows and eyelashes, beaked nose with alae nasi, low-set ears, thin lips, and micrognathia. Investigations revealed deafness and congenital hypothyroidism. We believe that this association of severe intrauterine growth retardation and congenital heart disease represents the components of this syndrome.

Congenital Hypothyroidism↗

Variable clinical expression of Holt-Oram syndrome in three generations.

Holt-Oram syndrome is a distinct autosomal dominant entity presenting with upper limb defects and cardiac abnormality. No correlation between the severity of the heart and the limb defects has been established. Here we report variable clinical expression of Holt-Oram syndrome in three generations. The grandfather presented with typical upper limb defects: phocomelia of arms with three digits on each hand, congenital heart defect and narrow shoulders. His son manifested cardiac conduction disturbance with no congenital heart or skeletal defect. The granddaughter showed ventricular septal defect and moderate radial deviations of both hands with no obvious hypoplasia of the extremities. Clinical data of the presented family suggests lack of penetrance with respect to skeletal and structural cardiac abnormalities in the Holt-Oram syndrome.

Ectromelia↗

Ambulatory electrocardiographic monitoring in healthy newborn infants.

Twenty-four hour ambulatory electrocardiographic monitoring is a useful method to document dysrhythmias and to assess treatment response. Various studies have been done in the pediatric age-group to determine normal heart rate values. In this study we determined the heart rate and rhythm patterns of 25 healthy newborn infants whose ages ranged between 3-10 days (mean 6.5 days). There were 15 males and 10 females. The maximum heart rate in these infants was 175-231 beats/min (207 +/- 14), minimum heart rate 60-121 beats/min (93 +/- 16) and the average heart rate was 130-161 beats/min (143 +/- 9). Five infants (20%) demonstrated marked sinus dysrhythmia, seven infants (28%) had ventricular premature contractions, two infants (8%) had supraventricular premature contractions, and five infants (20%) showed junctional rhythm disturbance. The sinus pause did not exceed 1.2 sec and there was no evidence of atrioventricular conduction disorders, or supraventricular-ventricular tachycardia attacks. Our results were consistent with previous studies carried out in newborn infants. Dysrhythmias were detected during 24-hour ambulatory electrocardiographic monitoring in our study group. Since they were generally benign, they need no treatment.

Arrhythmia, Sinus↗

Short- and intermediate-term efficacy of amiodarone in infants and children with cardiac arrhythmia.

The antiarrhythmic effect of amiodarone was examined in this retrospective study in a group of 20 patients with a mean age of 8.5 +/- 6.7 years (range 42 days to 20 years, median 9 years). Five patients with atrial flutter, one patient with atrial fibrillation, two patients with an intermediate rhythm between atrial flutter and atrial fibrillation, four patients with chaotic atrial tachycardia, three patients with atrioventricular reentry tachycardia, two patients with junctional ectopic tachycardia, and three patients with ventricular arrhythmias were treated with amiodarone. The mean duration of therapy was 9.1 +/- 12.3 months (range 1 month to 4 years). Before amiodarone treatment, 18 patients had been unresponsive to various antiarrhythmic drugs (range 1-8, median 2). Two patients received amiodarone as an initial therapy. It was administered orally at a dose of 10 mg/kg once per day for 10 days and then decreased to 5 mg/kg once per day. Amiodarone was effective in 16 patients (80%). Side effects occurred in three patients, including thyroid dysfunction, elevation of liver enzymes, and keratopathy. All side effects disappeared upon cessation of the therapy. We recommend amiodarone for the treatment of childhood arrhythmias, especially for the refractory types.

Administration, Oral↗

Vasovagal syncope: asystole provoked by head-up tilt testing under sertraline therapy.

Syncope is defined as a sudden transient loss of consciousness. Vasovagally mediated hypotension and bradycardia are believed common, yet difficult to diagnose, causes of syncope in healthy children and adolescents. These episodes are often both sudden and sporadic in nature and, if recurrent and severe (malignant vasovagal syncope), can be a source of morbidity and possibly mortality. Head-up tilt testing has emerged as a useful investigation in patients who are thought to have recurrent vasovagal syncope with systemic hypotension, bradycardia, or both, and it has been suggested as a potential method to test for vasovagal episodes. Sertraline hydrochloride, a serotonin reuptake inhibitor, has been reported to be effective in preventing the vasovagal syncopal episodes in children and adults. Here, two cases of recurrent, unexplained syncope are presented. Both were under sertraline therapy and underwent provocative head-up tilt testing that resulted in asystole.

1-Naphthylamine↗

Interruption of the distal left pulmonary artery with pulmonary arteriovenous fistulas and atrial septal defect.

A seven-year-old boy with interrupted left pulmonary artery, arteriovenous fistulas and atrial septal defect is presented. The anomalies were identified by echocardiography and angiography. On pulmonary artery angiograms, left pulmonary artery discontinuity (as though the distal segment had been interrupted), diffuse granulary opacification of right lung fields, and early visibility of the left atrium were observed.

Arteriovenous Fistula↗

Bruce treadmill test in healthy Turkish children: endurance time, heart rate, blood pressure and electrocardiographic changes.

Heart rate, systolic and diastolic blood pressure and electrocardiographic changes were studied in 80 healthy children during treadmill exercise with Bruce protocol. Mean duration of exercise in boys increased from 10.01 +/- 1.61 minutes at age four to six years with a mean body surface area of 0.75 +/- 0.06 m2, to 17.86 +/- 2.66 minutes at age 13 to 15 years with a mean body surface area of 1.48 +/- 0.10 m2. Mean endurance time in girls increased from 11.06 +/- 1.92 minutes at age four to six years with a mean body surface area of 0.76 +/- 0.08 m2, to 15.69 +/- 2.23 minutes at age 13 to 15 years with a mean body surface area of 1.41 +/- 0.07 m2. Mean maximal heart rate was 193.38 +/- 10.89 beats/minute in boys and 196.78 +/- 10.99 beats/minute in girls. The maximum level of systolic blood pressure attained at peak exercise was lower in girls. Although data of healthy Turkish children including mean endurance time, heart rate and blood pressure responses to exercise were consistent with the results from several countries using the Bruce protocol, mean maximal heart rates for all groups were slightly higher than those obtained with the Balke protocol. The data obtained from this study offers age- and size-appropriate normal data in both sexes in healthy Turkish children and may be used as reference values during treadmill exercise.

Adolescent↗

Detection of early anthracycline-induced cardiotoxicity in childhood cancer with dobutamine stress echocardiography.

Asymptomatic long-term survivors of childhood cancer treated with anthracyclines may have latent cardiac dysfunction which is undetected by commonly used echocardiographic methods. A more sensitive echocardiographic screening test, dobutamine stress echocardiography, was performed on 22 patients (mean age 9.10 +/- 3.79 years) treated with 75 to 450 mg/m2 of anthracyclines (mean 210.45 +/- 127.34) and results were compared with 22 healthy age-matched control subjects. Echocardiographic Doppler studies were performed after each dobutamine infusion of 0.5, 2.5, 5 and 10 micrograms/kg/min. Although left ventricular mass was decreased and end-systolic walls stress increased in the patient group when compared with the control subjects (p < 0.01 and p < 0.05, respectively), no differences were found between shortening fraction and ejection force in control subjects and patients, at rest and during each dobutamine infusion. A decreased mitral E/A ratio (ratio of early-to-late peak filling velocity) was demonstrated in anthracycline-treated patients only during dobutamine infusion (p < 0.01). Our data showed left ventricular diastolic dysfunction during intropic stimulation with dobutamine, and suggest that dobutamine stress echocardiography is a useful technique for evaluating the cardiac status of anthracycline-treated patients on a long-term basis.

Adolescent↗