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Biomedical subjects

H H Kramer

Publications and source records attributed to H H Kramer.

At least 19 recordsLinked to original sources
PubMed2003

Experience with transcatheter closure of secundum atrial septal defects using the Amplatzer septal occluder: a single centre study in 236 consecutive patients.

AIM: To evaluate the safety and efficacy of transcatheter closure of secundum atrial septal defects (ASD) with the Amplatzer septal occluder. METHODS: 236 consecutive patients with a significant ASD (age 6 months to 46 years, median 5 years; body weight 6.5-79 kg, median 18 kg) were considered for transcatheter closure with the Amplatzer septal occluder; 18 patients with defects that were too large or with a deficient inferior margin were excluded from attempted transcatheter closure after initial transthoracic (4) or transoesophageal echocardiography (14). RESULTS: At cardiac catheterisation, devices were not implanted in 18 patients because the stretched diameter of the ASD was too large (4), the device was unstable (4), compromised the mitral valve (1), or obstructed the upper right pulmonary vein (1); eight patients with additional systemic or pulmonary vein anomalies (5) or a Qp:Qs less than 1.5 (3) were excluded after angiographic and haemodynamic assessment. Thus ASD closure was done successfully in 200 patients (procedure time 25-210 minutes, median 66 minutes; fluoroscopy time 2.5-60 minutes, median 12 minutes), among whom 22 had multiple ASDs (14) or a septal aneurysm (8). The diameter of the devices ranged between 6-34 mm. Severe procedure related complications (retroperitoneal bleeding, air embolism) occurred in two cases. At follow up (33 days to 4.3 years, median 2.3 years) complete closure was documented in 94%, with a trivial residual shunt in 12 patients. CONCLUSIONS: The Amplatzer septal occluder is very efficient and offered interventional ASD closure in 84.7% of our group of consecutive patients, with excellent intermediate results.

Adolescent↗
PubMed2002

Influence of the pulmonary annulus diameter on pulmonary regurgitation and right ventricular pressure load after repair of tetralogy of Fallot.

OBJECTIVE: To assess the influence of the pulmonary annulus diameter after reconstruction of the right ventricular (RV) outflow tract at repair of tetralogy of Fallot on pulmonary regurgitation and RV pressure load; and to evaluate the impact of pulmonary regurgitation on RV size and function. SETTING: Paediatric cardiology and diagnostic radiology departments of a tertiary referral centre. PATIENTS: 67 patients were examined at a median of 4.8 years after repair of tetralogy of Fallot by means of biplane angiocardiography and magnetic resonance imaging (MRI). MAIN OUTCOME MEASURES: Pulmonary annulus diameter and area, pulmonary regurgitant fraction, RV to left ventricular (LV) systolic pressure ratio, RV end diastolic volume, and RV ejection fraction were assessed. RESULTS: There was a significant positive correlation between pulmonary annulus area indexed to body surface area and pulmonary regurgitation (angiocardiography: r = 0.55, p < 0.001; MRI: r = 0.59, p < 0.001). No significant correlation was found between pulmonary annulus index and RV to LV systolic pressure ratio even in patients with small pulmonary annulus areas (r = -0.24, NS). Pulmonary regurgitant fraction was positively correlated with normalised RV end diastolic volume (angiocardiography: r = 0.42, p < 0.05; MRI: r = 0.56, p < 0.01). RV ejection fraction decreased with increasing pulmonary regurgitation (angiocardiography: r = -0.42, p < 0.05; MRI: r = -0.41, p < 0.05). CONCLUSIONS: The extent of pulmonary regurgitation after tetralogy of Fallot repair correlates with the postoperative size of the pulmonary annulus and is closely correlated with the enlargement of the RV. An enlargement of the pulmonary annulus to the second lower standard deviation of normal results in a decrease of pulmonary regurgitation and is sufficient to achieve adequate RV pressure unloading.

Adolescent↗
PubMed2002

[Biplane angiographic volumetry of the right and left heart ventricle with optical image pairing].

Compared to single plane angiographic systems, biplane systems offer the possibility of a merged evaluation of the two x-ray projections. A computer program was developed that allows the assessment of enddiastolic and endsystolic volumes and frame-by-frame analysis of the left and right ventricle based on representing the biplane angiograms as optimal paired images. Optimal pairing means the magnifications are fitted, resulting in identical scales for objects located in the isocenter of the gantry; furthermore the images are rotated such that paired epipolar lines in both planes represent the same cross section of a centered object. The improved border tracing is proved by comparing the vertical extents from the lateral and frontal projection of the right ventricle. The standard deviation of the differences were significantly (p < 0.01) reduced as compared to the generally used unpaired evaluation.

Angiography↗
PubMed2001

Correction of tetralogy of Fallot: does the time period of surgery influence the outcome?

BACKGROUND: The perioperative outcome of patients with tetralogy of Fallot (TOF) seems to have improved over the last four decades. METHODS: To prove this hypothesis, we retrospectively analysed the data of 269 TOF patients operated on between 1975 and 1999 in our institution. RESULTS: Over the years, younger patients (median age 1975 - 1980: 4.5 years, 1995 - 1999: 0.9 years) were operated on with a lower mortality (1975 - 1980: 8.6 %, 1995 - 1999: 2.4 %). Residual defects such as pulmonary stenosis or insufficiency and VSD occurred with a similar frequency over time, whereas rhythm disturbances were significantly reduced (1981 - 1985: 51.2 %, 1995 - 1999: 24.4 %, p = 0.012). Postoperative length of hospital stay was significantly (p < 0.05) shorter in the years 1995 - 1999 (11.0 - 11.4 days) than in 1975 - 1980 (16.9 +/- 16.5 days). CONCLUSIONS: Over time periods, there was a trend towards lower mortality and towards operating on patients in a younger age. The rate of rhythm disturbances and the LOS after surgery proved to be reduced during the last decade. These differences did not turn out to be statistically significant. Therefore, we conclude that the time period of surgery has only little impact on the early outcome of patients after definitive correction of TOF.

Age Factors↗
PubMed2001

Tetralogy of Fallot: influence of surgical technique on survival and reoperation rate.

BACKGROUND: The influence of different surgical techniques in patients with Tetralogy of Fallot (TOF) on long-term survival and reoperation rate is still a matter of controversy. PATIENTS AND METHODS: The data of 266 patients (152 male, 114 female, mean body weight: 13.4 +/- 11.9 kg, mean age 4.1 +/- 6.0 years) with TOF, including 30 patients (11.2 %) with TOF/pulmonary atresia, were analyzed retrospectively. A palliative surgical procedure preceded definite correction between 1975 and 1999 in 46 patients (17.5 %). The surgical technique consisted of a transannular patch in 103 patients (40.1 %); in 133 patients (51.8 %), a non-transvalvular technique was used. In 33 patients (12.3 %), a conduit was implanted into the right ventricular outflow tract (RVOT). For surgical access to the cardiac defects, a transventricular approach was used in 138 patients, and a transatrial/trans-pulmonary approach in 26 patients. The mean follow-up time of all patients was 6.6 years. RESULTS: Kaplan-Meier survival for the entire group was 86.2 % at one year and remained stable at 85.6 % after 5 years. The 30-day mortality was 10.1 % (27 patients). Fatal risk factors were: previous cardiac surgery, preoperative oxygen saturation (SO(2)) < 80 %, diagnosis of pulmonary atresia, prolonged aortic clamping or bypass time, postoperative infections, and early revisions. Freedom from reoperation was 91.6 % after 5, 84.5 % after 10, and 52.6 % after 20 years. There was no correlation between the different surgical techniques (transannular patch, non-transvalvular techniques, transventricular approach) applied and the mortality or the rate of reoperations. CONCLUSIONS: In our series of TOF patients operated over a period of 25 years, we were unable to assess an influence of the surgical technique used for definite correction on mortality or reoperation rate. Pulmonary atresia in patients with TOF is associated with a higher risk of death and reoperation.

Adolescent↗
PubMed2001

Transcatheter closure of persistent ductus arteriosus in infants using the Amplatzer duct occluder.

AIM: To evaluate whether transcatheter closure with the Amplatzer duct occluder offers an alternative to surgical treatment in infants with a persistent ductus arteriosus. METHODS: 12 patients under 1 year of age (age 1-11 months, body weight 2.6-8.7 kg) with clinical and echocardiographic findings of a significant duct were considered for transcatheter closure with the Amplatzer occluder. The device is made of a Nitinol and polyester fabric mesh and provides occlusion by stenting the duct. Measured angiographically, the narrowest diameter of the ducts ranged from 1.5-5 mm; in six patients pulmonary hypertension was also present. RESULTS: The devices were implanted and complete duct occlusion was demonstrated during follow up in 10 patients. Procedure related difficulties occurred in nine of the 12 cases and led to relatively long procedure and fluoroscopy times (procedure time 50-180 minutes, median 80 minutes; fluoroscopy time 4.9-49 minutes, median 16 minutes). In two infants transcatheter closure could not be achieved and surgical duct ligation had to be carried out. CONCLUSIONS: In small infants with a persistent ductus arteriosus the Amplatzer duct occluder offers an alternative to surgical treatment, but further improvement of the implantation system is necessary before the procedure can be recommended as the treatment of choice.

Alloys↗
PubMed2000

A novel method for real-time magnetic marker monitoring in the gastrointestinal tract.

In internal medicine, a simple method for the functional examination of the gastrointestinal tract without the risk of radiation exposure is required. We describe a novel principle based on the monitoring of magnetic markers which meets these demands. Our method employs a special permanent magnet which is repeatedly aligned by a vertically oriented pulsed magnetic field. Due to this alignment, the marker position can be derived from the stray field components measured by commercial field sensors. Our method was evaluated by means of a 3D intestinal phantom. The monitoring procedure yielded the time course of the marker position as a 3D plot either in real-time or as a time-lapse movie. The spatial resolution, expressed by the mean square deviation, was better than 10 mm and is thus sufficiently high to distinguish between adjacent loops of the gut. The temporal resolution, i.e. the minimum time between two successive measurements, was about 1 s. The presented method has very moderate technical demands and allows us to monitor magnetic markers in real-time. The technique may be useful with respect to functional examination of the gastrointestinal tract. In pharmaceutical research, our method offers the opportunity for remote drug release at any position of the gut.

Biomarkers↗
PubMed1999

Transcatheter closure of secundum atrial septal defects with the new self-centering Amplatzer Septal Occluder.

AIMS: The study was set up to find out whether a new self-centering prosthesis for transcatheter closure of secundum atrial septal defects could overcome the disadvantages of previously described devices. METHODS AND RESULTS: Fifty-two consecutive patients with a significant atrial septal defect were considered for transcatheter closure with the Amplatzer Septal Occluder. The device, made of a Nitinol and polyester fabric mesh, provides a different approach to defect occlusion by stenting the atrial septal defect up to a stretched diameter of 26 mm. Three infants whose large defects were demonstrated on a transthoracic echocardiogram were excluded from transcatheter treatment. On transoesophageal echocardiography, 49 defects ranged from 6-26 mm, in one adult the defect measured 28 mm and this patient was excluded from attempted transcatheter closure. At cardiac catheterization in five further patients, devices were not implanted, in two because the stretched diameter exceeded 26 mm and in three the device was withdrawn because it was unstable or compromised the mitral valve. Thus, device closure was performed in 43 patients. At follow-up after 3 months the complete closure rate was 97%. CONCLUSION: The self-centering Amplatzer Septal Occluder is very efficient and user-friendly and offers interventional closure in 83% of an unselected group of patients presented with an atrial septal defect.

Adolescent↗
PubMed1999

Gross and fine motor development is impaired in children with cyanotic congenital heart disease.

Many factors may intervene with the motor development of children with congenital heart disease (CHD). Children aged 5 to 14 years with various CHD were examined for disturbances of gross and fine motor development using motometric tests and compared with 30 healthy controls. The results of the Körperkoordinationstest für Kinder (KTK) (a body coordination test for children) for gross motor development were significantly lower in patients with uncorrected cyanotic CHD (motor quotient MQ 74.8 +/- 11.7, mean +/- 1 standard deviation, n = 16) and after corrective surgery (MQ 81.2 +/- 16.6, n = 25) than in controls (MQ 102.8 +/- 11.8, n = 30). No relationship between these results and the cardiopulmonary exercise capacity was found. In patients with cyanotic CHD, significant deficits in fine motor development were present before corrective surgery (e.g. Zielpunktiertest [dotting] MQ 87.7 +/- 9.9 vs. 106.5 +/- 10.8), but already two years afterwards the results reached nearly normal values (MQ 97.1 +/- 17.0). In contrast, children with acyanotic CHD demonstrated normal gross and fine motor development. These results indicate that long-standing hypoxemia in infancy must be considered as an important cause of the pronounced motor disturbances. Early neurological evaluation of these children and a specialized motor physiotherapy are recommended.

Adolescent↗
PubMed1998

[Atrial ectopic tachycardia in infancy caused by tumor of the interatrial septum].

A case of atrial ectopic tachycardia in an infant probably caused by a small tumor in the interatrial septum is presented. The arrhythmia was successfully treated with amiodarone. Several histologic abnormalities are known to cause AET, but an intracardiac tumor detectable by two-dimensional echocardiography is extremely rare. AET -especially in childhood-as well as cardiac tumors show a tendency to regression, so that even in this case medical treatment should be the first therapeutic choice. Interventional or surgical treatment is required just for those patients with AET this is resistant to medical treatment or reoccurs after finishing the medical treatment.

Amiodarone↗
PubMed1995

Evaluation of low dose prostaglandin E1 treatment for ductus dependent congenital heart disease.

UNLABELLED: This study reports our experience with low-dose prostaglandin E1 (PGE1) treatment of 91 newborns with ductus dependent congenital heart disease (CHD). PGE1 efficacy, side-effects as well as the cardiovascular and respiratory profile of the patients were analysed. PGE1 doses > 0.02 microgram/kg per minute were used for only 5.3% of the total 23,656 h of treatment. The mean systolic blood pressures did not differ from the normal mean for patients with cyanotic CHD, while the diastolic values were lowered. Respiratory support was required only during 13.7% of the total treatment time. Apnoeas occurred in 21 (38%) of the 55 spontaneously breathing infants, who all had a cyanotic CHD. The incidence of apnoeas was lower during treatment with doses < 0.01 microgram/kg per minute. CONCLUSION: PGE1 can be successfully administered in lower doses than previously recommended. Especially high initial doses can be avoided and low maintenance doses allow long-term treatment without serious complications.

Alprostadil↗
PubMed1994

Clinical experience with propafenone for cardiac arrhythmias in the young.

Seventy-two children were treated with propafenone between 1980 and 1990. The mean age was 34 months (range 0-192). Arrhythmias included atrioventricular re-entry tachycardia in 32 patients (44%), atrial flutter in 16 (22%), atrial or junctional ectopic tachycardia in 10 (14%), atrial re-entry tachycardias in three (4%) and ventricular arrhythmias in 11 patients (16%). The efficacy of oral treatment was good in patients with atrio-ventricular re-entry tachycardia (80%), atrial flutter (71%) and atrial ectopic tachycardia (83%); it was poor in ventricular arrhythmias (40%). The mean oral dose was 13.5 mg.kg-1. day-1. Dosage and serum levels of propafenone did not differ whether the patients were treated successfully or not. No correlation between dosage and serum level was observed. Intravenous propafenone administration was only partially successful in suppressing supraventricular tachycardias (6 of 11 patients). The presence of a congenital heart defect and the time of onset of the arrhythmias had a significant influence on the efficacy of propafenone. Better results were observed in patients with normal hearts and in whom onset of arrhythmia was pre-natal (success 80%) as well as in patients with arrhythmias seen early after surgery for congenital heart defects (success 87%). Success (65%) was also observed in patients without congenital heart defects and postnatal onset of supraventricular arrhythmias. Patients with ventricular or supraventricular arrhythmias late after corrective surgery showed the poorest response (31%).

Administration, Oral↗
PubMed1993

Distribution of myocardial beta-adrenoceptor subtypes and coupling to the adenylate cyclase in children with congenital heart disease and implications for treatment.

In congestive heart failure, down-regulation of myocardial beta-adrenoceptors (beta-AR) due to an elevated sympathetic tone is well known. In infancy and childhood, heart failure is usually related to congenital heart disease (CHD). Therefore, 71 samples of right atrial tissue of infants and children with CHD undergoing cardiac surgery were studied for beta-adrenoceptor density and distribution of the beta 1-/beta 2-AR subtypes. In 49 cases, the coupling of the beta-AR to the adenylate cyclase (AC) was examined. In a further study of 19 myocardial samples, AC was selectively stimulated with beta 1- or beta 2-AR whereas the other subtype was blocked by an antagonist. The following results were obtained: (1) Infants and children with severe acyanotic or cyanotic CHD had severely reduced beta-AR densities. (2) In most of the cases, the beta-AR down regulation is beta 1-subtype selective, but in critically ill newborns with congenital aortic valve stenosis or transposition of the great arteries, there is additional significant beta 2-AR down-regulation. In Fallot patients treated with the beta-antagonist propranolol, a significant increased beta-AR number compared with untreated Fallot patients was found. (3) beta-Adrenoceptor reduction in CHD is correlated with elevated noradrenaline plasma levels, thus proving a sympathetic dysregulation. (4) In CHD with moderate hemodynamic load, beta 2-AR coupling to AC was markedly more efficient than beta 1-AR coupling. The small number of myocardial beta 2-AR produced most of the cyclic adenosine monophosphate. (5) In severe acyanotic and cyanotic CHD, a partial decoupling of the beta 2-AR to the AC occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Cyclases↗
PubMed1993

Non-invasive evaluation of left ventricular systolic function late after coarctation repair: influence of early vs late surgery.

The study was designed to assess non-invasively the long-term effect of coarctation repair on systemic blood pressure, left ventricular (LV) muscle mass (LMM) and LV systolic function. Blood pressure and pressure gradients across the coarctation site were measured at rest and during exercise. LV systolic function and LMM were assessed by echocardiography. Twenty-eight patients late after successful coarctation repair were divided according to their age at surgery into two groups: group 1: < 1 year (10 days-12 months, mean 0.2 years) and group 2: > 1 year (1-19 years, mean 9.7 years). A group of age- and sex-matched patients with normal LV function served as controls. LMM was increased late postoperatively in both groups irrespective of the age at surgery and was correlated significantly with the elevated systolic blood pressure and the residual pressure gradient at exercise. End-systolic wall stress was normal at rest and the stress/velocity relationship revealed normal contractility in all patients. Despite successful operation of aortic coarctation, residual LV hypertrophy persists 2 to 19 years after surgery irrespective of the age at surgery. LV systolic function is normal. Hypertrophy can be explained by the residual arm-leg pressure gradient during exercise which persists even after successful repair.

Adolescent↗
PubMed1992

Intermediate-term clinical and hemodynamic results of the neonatal arterial switch operation for complete transposition of the great arteries.

We prospectively evaluated 49 consecutive hospital survivors of the arterial switch operation for complete transposition and intact ventricular septum by clinical examination, echocardiography, cardiac catheterization, 12-lead and 24-h Holter ECG. The mean length of follow-up was 40 +/- 18 months. Forty-six children are clinically asymptomatic without medication, 2 died due to coronary related left ventricular dysfunction 3 and 12 months after surgery, and 1 required reoperation because of severe bilateral pulmonary branch stenoses. Except for this case, cardiac catheterization (n = 23) revealed a mean gradient of only 17 +/- 8 mmHg between the right ventricle and distal pulmonary arteries. Left ventricular end-diastolic volume was within normal limits except for 2 cases with volumes slightly below normal, the mean ejection fraction was 78 +/- 5%, and end-diastolic and end-systolic ventricular shapes were normal. The mean cardiac index was 4.14 +/- 0.69 l/min/m2. Left ventricular end-systolic wall stress to velocity of fiber shortening relation was normal in all cases examined (n = 15), indicating normal myocardial contractility. Significant neoaortic valve insufficiency was never observed despite considerably enlarged aortic roots. Twenty-four-hour Holter ECG records (n = 46) provided no evidence of serious atrial arrhythmias, especially sinus node dysfunction. These encouraging intermediate-term results make the arterial switch operation the treatment of choice at present, for neonates with simple transposition.

Child, Preschool↗
PubMed1992

Atrial automatic tachycardia in infancy and childhood.

Twenty-one cases (13 male, eight female) of atrial automatic tachycardia (AAT) assessed by standard and Holter-ECG in otherwise healthy infants and children have been documented. AAT was incessant in 12 patients, repetitive in seven, and of undetermined type in the remaining two. The frontal P wave axis suggested an ectopic focus in the high right atrium or right atrial appendage in 13 patients, in the low right atrium in one patient, and in the left atrium in seven patients. Thirteen out of 14 patients with the incessant or undetermined type of AAT were symptomatic, in contrast to only two of seven patients with the repetitive type. All patients were treated with between one and eight (median three) antiarrhythmic drugs. The most effective drug was amiodarone, followed by the class I C antiarrhythmic drugs, propafenone and flecainide. At present, all patients are alive 4 months to 21 years (median 2.5 years) after diagnosis of AAT. Twelve patients are in sinus rhythm, five of them without any medication. Nine patients still have AAT, which, however, is repetitive or intermittent in all but one. In conclusion, AAT is an unusual, and in its incessant form often severely symptomatic arrhythmia, which is resistant to conventional antiarrhythmic medication. However, amiodarone and class I C antiarrhythmic drugs are frequently effective. Since medical treatment with these drugs is often successful, and AAT may resolve completely, a conservative approach is indicated in many cases.

Adolescent↗