[Evaluation of abnormal myocardial wall motions in patients with univentricular heart by tissue Doppler echocardiography]

INTRODUCTION

Assessment of systolic and diastolic ventricular function in children and adults with morphologically and functionally univentricular heart is difficult using the conventional echocardiographic methods. Quantitative assessment of systolic and diastolic wall motion by TDE may provide information on abnormal systolic and diastolic ventricular function. Thus, the object of this study was to analyze the patterns of anterior and posterior wall motions in children with univentricular heart after palliative Fontan operation in comparison to normal subjects.

PATIENTS AND METHODS

We investigated 21 patients of an average age of 10.1 years (range 4.2 to 32 years) with the primary diagnosis of univentricular heart and tricuspid atresia after a median period of 4.3 (range 1.2 to 8) years after cavo-pulmonary anastomosis (Fontan procedure) and in comparison to a normal collective of children without cardiovascular malformations. For investigation we used the novel tissue Doppler echocardiography (TDE) (EchoPack 6.3.6, Vingmed, Norway). Thereby we chose the standardized apical view and evaluated the left and right annular systolic (S(T)), early diastolic (E(T)) and atrial (A(T)) motion. We also registered the acceleration and deceleration time of each obtained curve.

RESULTS

In comparison to the posterior myocardial wall the velocities at the anterior wall of the rudimentary ventricle were significantly reduced in all patients with tricuspid atresia and univentricular heart (p<0.0001). Particularly the annular systolic and diastolic wall motions of the rudimentary ventricle as well as their deceleration and acceleration time in patients with univentricular hearts differed significantly from those in healthy persons.

CONCLUSION

Abnormal myocardial wall motion is detectable in children and adults with univentricular heart after palliative cardiac procedures using tissue Doppler echocardiography. The hemodynamic value of the measured abnormal wall motions, however, need further comparative studies.

[A delayed life-threatening complication after uneventful varicella infection: transient complete heart block]

A 9 year old boy presented with uncharacteristic gastroenteric complaints due to a complete heart block 9 days after an uneventful varicella infection. Echocardiographically there were no signs of gross myocardial involvement. Bradydysrhythmia necessitated isoproterenol application however without the need for temporary transvenous cardiac pacing. After a short period of second-degree atrioventricular block and transient left bundle branch block the rhythm recovered completely and sinus rhythm is maintained so far. Worrying is the delayed onset of this complication after an uneventful course of a typically undangerous children's disease. Presumably a remaining inflammatory reaction in different parts of the specific conducting system has to be assumed. The long lasting prognosis of the atrioventricular conduction properties remains to be seen.

[Transthoracic pacing in a very low birth weight infant with congenital complete atrioventricular block - Case report]

We report our experience of pacemaker treatment in a premature infant of 832 grams with congenital complete atrioventricular block due to maternal Sjögren's Syndrome. She was delivered by cesarean section at an estimated gestational age of 26 weeks because of fetal bradycardia, decreasing fetal movements and hydrops. Immediate postnatal transesophageal ventricular pacing was not successful, whereas transthoracic pacing with self-adhesive patch electrodes adapted to body size resulted in an effective increase of the infant's heart rate until operative application of temporary epimyocardial pacing wires ensured the external stimulation of the heart.

Preliminary analysis of arrhythmias after the Fontan operation with extracardiac conduit compared with intra-atrial lateral tunnel

BACKGROUND

It is to be expected that avoidance of the atrial suture line during extracardiac Fontan operation (ECFO) decreases the risk of postoperative arrhythmias.

METHODS

Two groups of consecutive patients (23 with lateral tunnel (LTFO) and 24 with extracardiac conduit) who underwent successful Fontan operations between 5/93 and 10/98 were comparatively analyzed. All patients had postoperatively standard ECG and 24-hour monitoring. During follow-up, all patients had 2 - 8 (mean 3) standard ECG recordings per year and 76 % of the patients a 24-hour Holter ECG once a year.

RESULTS

Median follow-up after ECFO and LTFO was 2.4 years and 4.5 years, respectively. The incidence of supraventricular tachyarrhythmias and bradyarrhythmias after ECFO versus LTFO was lower early after operation and during follow-up (p < 0.05). In follow-up, 20 ECFO patients (91 %) versus 11 patients after LTFO (52 %) remained in sinus rhythm (p < 0.01). Pacemaker insertion was required in 7 (33 %) LTFO patients but none of the ECFO patients (p < 0.01).

CONCLUSIONS

The extracardiac Fontan operation decreases the incidence of early and medium-term postoperative arrhythmias. Comparative long-term results are not yet available.

[DDD-pacemaker implantation in a 7-week-old infant: epicardial electrodes in intrapleural position]

Permanent pacing for complete heart block in newborns and small infants is a challenge concerning the mismatch between body size and pacemaker dimensions. As the abdominal position of the large pacemaker carries a considerable risk of healing disturbances, the intrapleural position of single chamber pacemakers is accepted as well. We report about a 7 week old infant with congestive heart failure due to a complete atrioventricular septal defect. The immature valve tissue led to recurrent, severe mitral valve incompetence and necessitated several valvuloplasty procedures and finally the implantation of a mechanical prothesis. Because of a postoperative complete heart block, a dual chamber pacemaker with epicardial steroid-eluting bipolar leads was implanted without specific fixation into the right pleural cavity during delayed sternal closure to ensure atrioventricular synchrony. Despite the capacious implant, adverse effects on hemodynamics and pulmonary function were not observed and the infant thrived normally. The DDD function of the pacemaker allowed the utilization of the infant's complete heart rate spectrum without restrictions due to the technically limited upper tracking rate of 180 bpm.

Percutaneous closure of large atrial septal defects with the Amplatzer Septal Occluder: technical overkill or recommendable alternative treatment?

To judge whether an Amplatzer Septal Occluder (ASO) can be used as a safe therapy instead of surgery for closure of large atrial septal defects > 25 mm in diameter, we report our experiences in 45 patients out of a cohort of 467 patients after successful ASO implantation within a period of 3 years. Median defect diameter was 28 mm (range 25-36), median age was 41.2 years (range 10.1-77.7 years). Body weight ranged from 33.5 to 112.0 kg (median 68 kg). Due to an inevitable reduction of the stent size with increasing distances of the discs fixed at the thicker part of the atrial septum in larger defects, we implanted devices 2-4 mm larger than the measured stretched diameter. Fluoroscopy times ranged from 2.0 to 24.4 minutes, with a median of 10.3 minutes. Follow-up studies were obtained after 48 hours and 1, 6, and 12 months, and then yearly. The median period of follow-up was 0.82 years (range 0.1-2.6). The complete occlusion rate was 91.1%. A trivial hemodynamically insignificant residual shunt remained in 8.9% of the patients. Three patients showed transient atrial tachyarrhythmias within the first 3 months after implantation and three remained in chronic atrial fibrillation. The excellent results in the short and medium term make Amplatzer device implantation a recommendable safe and effective alternative to surgery, even in selected cases with defects > 25 mm. Final judgement, however, is only possible after long-term follow-up.

[Interventional occlusion of atrial septum defects larter than 20 mm in diameter]

Over the last few years, various devices for the interventional closure of atrial septal defects (ASD) up to a diameter of 20 mm have been developed. We report our clinical experience in closing ASD with a diameter larger than 20 mm diameter with the Amplatzer Septal Occluder (ASO).

METHOD

The stretched diameter of the ASD was measured by inflating a sizing balloon within the defect until an indentation in the circumference in the balloon could be observed. An ASO with a stent diameter 2-4 mm larger than the indentation in the circumference of the balloon was chosen and implanted via 9-12 French sheaths. In contrast to the closure of smaller defects, pullback of the device onto the atrial septum was only performed when the connecting stent of the ASO was completely deployed in order to achieve maximal centering characteristics and optimal support of the retention skirt of the left atrial disc on the edges of the defect. Only then was the right atrial disc deployed and actively configured by advancing the sheath and the delivery cable against the atrial septum. Implantation was only attempted if the atrial septal rims (except the anterior rim around the aorta) measured more than 7 mm by echocardiography to avoid injury or disturbance of sensitive intracardiac structures. After placement, the fixation of the device and the mechanical stability was proven by an extensive "Minnesota wiggle". The ASO was released only when TEE showed no or a trivial residual color flow through the connecting stent; otherwise repositioning was performed.

RESULTS

Out of 352 patients (P) with successful closure of interatrial defects, 70 P (age: 1.1-77.3 years) had stretched defects larger than 20 mm diameter (median 22 mm diameter (20-36), 25/75% quartiles = 20/26 mm). Mean shunt size was Qp:Qs 2.1:1 (0.7-3.9:1), mean fluoroscopy time 10.9 min (0-63). Complete closure could be achieved in 85.7/93.1/100% after 3 months, 1 and 2 years, respectively. Besides 3 P with persistent atrial fibrillation, only 5 P showed transient atrial tachyarrhythmias, 2 only periprocedural and 3 within the first 3 months after implantation were treated with beta-blocker. In one patient, an acute embolization of the device occurred because a diminished posterior rim was not visualized by a monoplane TEE probe necessitating surgical explantation and defect occlusion. Despite oversizing the device, no "mushrooming" misconfiguration were observed.

CONCLUSION

Transcatheter closure of large atrial septal defects with the Amplatzer Septal Occluder is feasible, safe and effective. Risk of complications do not seem to occur more frequently than after closure of smaller defects if one adheres to certain sizing and implantation measures. The incidence of transient atrial tachyarrhythmias seems to be low.

Transthoracic pacing in a very low birth weight infant with congenital complete atrioventricular block

We report our experience of pacemaker treatment in a premature infant of 830 g with congenital complete atrioventricular block due to maternal Sjögren's Syndrome. The infant was delivered by cesarean section at an estimated gestational age of 26 weeks because of fetal bradycardia, decreasing fetal movements, and hydrops. Immediate postnatal transesophageal ventricular pacing was not successful, whereas transthoracic pacing with self-adhesive patch electrodes adapted to body size resulted in an effective increase of the infant's heart rate until operative application of temporary epimyocardial pacing wires allowed external stimulation of the heart.

[Is transcatheter occlusion of a persistent foramen ovale a possibility for the avoidance of a paradoxical embolism?]

BACKGROUND AND OBJECTIVE

Cerebral embolism may have different causes with sometimes serious consequences. If no specific reason can be found, paradoxical embolization through a persistent foramen ovale (PFO) is increasingly as a cause of the cerebral ischaemia. This study was undertaken to ascertain whether in patients with cerebral embolism occlusion of a PFO with a transcatheter technique can prevent further cerebral emboli.

PATIENTS AND METHODS

Indications for transcatheter occlusion were based on neurological signs (ischaemic stroke), cardiovascular diagnosis, and coagulation tests. Between August 1991 and July 1996, transcatheter occlusion of a PFO was performed in 28 fully anticoagulated patients (median age 37.8 [15.4-65.4] years). The mean PFO diameter was 9.5 mm (3-17), mean duration of fluoroscopy 18.3 (8.7-43.1) min. The Rashkind device was implanted in three patients, the Sideris buttoned device in 25. During the follow-up period (2-64 months; mean 13 months) renewed neurological symptoms occurred in only one patient. Transoesophageal echocardiography excluded thrombi on the implanted device or in the left atrium, and a residual PFO. The cause of the one neurological episode is therefore not clear. All other patients have remained free of symptoms and recurrence without anticoagulation after placement of the device.

CONCLUSIONS

Transcatheter occlusion of a PFO is a relatively simple and safe procedure. Our results suggest that it can at least lower the incidence of further cerebral embolizations. The clinical value of the method in comparison with anticoagulation requires further study.

Surgical emergency embolectomy for the treatment of fulminant pulmonary embolism in a preterm infant

A massive pulmonary embolism, demonstrated by echocardiography developed in a 3-week-old preterm infant. An etiologic explanation could not be obtained from either history or clinical and laboratory findings. Pulmonary embolectomy was performed as an emergency procedure because of severe hemodynamic impairment despite intensive medical therapy. In children who have massive pulmonary embolism who remain in a compromised hemodynamic state despite intensive medical therapy, pulmonary embolectomy may be considered the alternative emergency treatment.

[Aerosolized prostacyclin for preoperative evaluation and post-cardiosurgical treatment of patients with pulmonary hypertension]

BACKGROUND

Inhaled nitric oxide (NO) has been shown to selectively lower pulmonary vascular resistance and is applied in patients with pulmonary hypertension (PHT). However, application and monitoring is complex and not always successful ("non-responders"). We evaluated the effect of aerolized prostacyclin (aePGI2) as a therapeutic alternate to NO.

PATIENTS AND METHODS

aePGI2 and NO were applied to patients with different causes of pulmonary hypertension (Group 1a: preoperative patients with intracardiac shunting defects and Eisenmenger's disease, n = 30; Group 1b: patients with primary or postoperative PHT, n = 13; Group 2: PHT immediately following surgery for congenital heart disease, n = 6).

RESULTS

Pulmonary vascular resistance could be lowered significantly (Group 1a: from 91% of systemic vascular resistance to 58% with NO and 53% with aePGI2; Group 1b: from 20.2 Wood Units*m2 to 13.4 and 11.3; Group 2: from 24.9 Wood Units*m2 to 9.5 and 10.5); cardiac index increased (Group 1b: from 2.96 to 3.55 and 3.96 l/min*m2, Group 2: from 1.57 to 1.89 and 2.00 l/min*m2).

CONCLUSIONS

The short-term application of aePGI2 shows a selective pulmonary vasodilation similar to NO. Given adequate monitoring, aePGI2 appears to be useful for the acute treatment of PHT.

Long-term extracorporeal membrane oxygenation in a newborn child after arterial switch operation

A 7-day newborn girl with d-transposition of the great arteries (d-TGA) and complex coronary anatomy developed global myocardial dysfunction after arterial switch operation despite establishment of an effective coronary circulation. Extracorporeal membrane oxygenation was used for circulatory support for 163 h after the operation. On day 7 after surgery she was successfully weaned from extracorporeal membrane oxygenation and is currently symptom-free 10 months after the operation. This case illustrates the effectiveness of extracorporeal membrane oxygenation for circulatory support after the arterial switch operation. In such cases, establishing adequate coronary circulation during surgery mandatory to ensure a successful postoperative myocardial recovery.

[Successful treatment with hyperbaric oxygen following severe cerebro-arterial gas embolism]

We report on a patient suffering from a severe cerebral arterial gas embolism associated with decompression from a simulated high pressure chamber dive. Treatment with hyperbaric oxygen (HBO) commenced immediately after the accident and was continued subsequently for 8 weeks with a total of 49 HBO-sessions. Despite initial transitory amaurosis and flaccid tetraplegia lasting for two weeks the patient made a near complete recovery except for circumscript numbness and paraesthesia confined to the left tibia and palm. This case underscores the need to consider patients with cerebral arterial gas embolism for HBO treatment and the potential value of a subsequent long-term HBO therapy.

Muscle fiber orientation in the development and regression of right ventricular hypertrophy in pigs

The development and regression of right ventricular hypertrophy was investigated in 12 pigs with special reference to changes in ventricular function and myocardial fiber orientation. Nine ventricles were pressure-loaded by banding the pulmonary artery for 28-81 days, and four of them were then released from the load by removing the band. Right ventricular systolic pressure (RVSP), end-diastolic pressure (RVEDP) and end-systolic volume index (ESVI) increased significantly during banding and decreased after debanding. End-diastolic volume index (EDVI) and stroke volume index (SVI) showed no significant change during banding and after debanding. The weight of the right ventricle relative to both ventricles (RV/TV) and the thickness of muscle fibers were increased significantly in the loaded ventricles, and reduced again to the control level in ventricles released from the load. The intramyocardial distribution of angles (theta) of inclination of muscle fibers from the transverse plane of the outflow tract was estimated histometrically. There was a significantly larger proporation of circularly oriented fibers (magnitue of theta less than or equal to 30 degrees) in the pressure-loaded ventricles than in the control, whereas these fibers decreased again to the control level after removal of the pressure load. The present findings indicates that 1) the right ventricular hypertrophy induced by pressure loading is characterized not only by an increase in ventricular weight and muscle fiber thickness, but also by a change in intramyocardial fiber orientation, and 2) the hypertrophic right ventricle can regress both functionally and morphologically to a normal state after removal of the pressure load.

Response of the right ventricle to progressive pressure loading in pigs

The purpose of this study was to determine the speed and duration of progressive pressure loading of the right ventricle to systemic pressure levels, which allows right ventricular adaptation without myocardial impairment at rest. In 8 pigs with an average weight of 22 kg progressive right ventricular pressure loading of different speeds and durations was induced with a newly developed constrictor. Pressures in the right atrium, right ventricle, and pulmonary artery as well as angiocardiographic volume parameters of the right ventricle were determined weekly over a period of 4 to 7 weeks. A fast progressive right ventricular pressure increase of 3.4 mm Hg/day during 3 weeks was associated with a 20-30% reduction of ejection fraction and a 100% increase of the end-systolic volume. Increase of end-diastolic pressure was 3 to 5 fold. A slow progressive pressure increase of 1.5 to 2.2 mm Hg/day to 100 mm Hg within 4 to 5 weeks was associated with an increase of the end-diastolic pressure to a level observed in systemic ventricles, while change of ejection fraction and end-systolic volume was minimal. The faster the increase of right ventricular pressure the flatter was the peak systolic pressure/end-systolic volume relationship. It is concluded that in contrast to sudden and fast progressive increase of afterload slow progressive increase of afterload to systemic levels does not impair right ventricular myocardial function.

A new device for slow progressive narrowing of vessels

The purpose of this work was to develop a device which allows slow progressive banding of a great artery in infants within 4 to 5 weeks. Employed was the hygroscopic casein ameroid. When brought in contact with fluids, an ameroid cylinder expands characteristically. An early phase of fast expansion proceeds gradually to a phase of slow growth. Size, shape, and encasement of ameroid as well as temperature and type of surrounding fluid modify but do not alter the typical pattern of expansion. The developed constrictor (weight: 5.8 kg, length: 18 mm, diameter: 12 mm) includes a stainless steel socket containing an ameroid cylinder (length: 8.5 mm, diameter: 8 mm). The expanding ameroid pushes a piston with a concave extension (makrolon) a maximum of 2 mm against the artery, which is fixed to the metal housing by a teflon band (width: 4 mm, thickness: 0.5 mm). The band runs in 2 fitting grooves on the metal housing to which it is fixed by a metal ring with a precisely manufactured internal thread allowing exact tightening and loosening of the band around the artery. Utilization of inert materials like teflon, makrolon, and stainless steel warrants experimental and possibly clinical application of the developed small constrictor.