Pavel Vojtovič

Resynchronization pacing is a useful adjunct to the management of acute heart failure after surgery for congenital heart defects

The acute hemodynamic effect of atrioventricular (AV) and inter/intraventricular (IV) resynchronization accomplished by temporary pacing using multiple epicardial pacing wires was evaluated in 20 children (aged 3.4 months to 14.0 years) after surgery for congenital heart defects fulfilling the following criteria: (1) presence of AV and/or IV conduction delay, and (2) need for inotropic support. AV resynchronization (n = 13) was achieved by AV delay optimization during atrial synchronous right ventricular outflow tract pacing. IV resynchronization (n = 14) was accomplished by atrial synchronous pacing from the right ventricular lateral wall in 7 patients with right bundle branch block and normal AV conduction and by atrial synchronous multisite ventricular pacing in another 7 patients with previously performed AV resynchronization. Compared with baseline values, AV resynchronization resulted in an increase in arterial systolic, mean, and pulse pressures by 7.2 +/- 8.3% (p <0.01), 8.6 +/- 8.1% (p <0.005), and 6.9 +/- 13.5% (p = NS), respectively. IV resynchronization used either alone or added to previously performed AV resynchronization led to a pressure increase of 7.0 +/- 4.7%, 5.9 +/- 4.7%, and 9.4 +/- 7.8%, respectively (p <0.001 for all). The combined effect of AV and IV resynchronization resulted in a systolic, mean, and pulse pressure increase of 10.2 +/- 5.0% (range 4.0 to 19.1), 8.6 +/- 5.4% (range 0.8 to 14.8), and 15.2 +/- 8.5% (range 6.1 to 33.3), respectively (p <0.001 for all). The increase in systolic arterial pressure after IV resynchronization was positively correlated with the initial QRS duration (r = 0.62, p <0.05) and extent of QRS shortening (r = 0.66, p <0.05). In conclusion, resynchronization pacing led to a significant increase in arterial blood pressure and was a useful adjunct to the treatment of acute postoperative heart failure in patients with AV and/or IV conduction delay.

Predictors of left ventricular remodelling and failure in right ventricular pacing in the young.

Aims To identify risk factors for left ventricular (LV) dysfunction in right ventricular (RV) pacing in the young. Methods and results Left ventricular function was evaluated in 82 paediatric patients with either non-surgical (n = 41) or surgical (n= 41) complete atrioventricular block who have been 100% RV paced for a mean period of 7.4 years. Left ventricular shortening fraction (SF) decreased from a median (range) of 39 (24–62)% prior to implantation to 32 (8–49)% at last follow-up (P < 0.05). Prevalence of a combination of LV dilatation (LV end-diastolic diameter >+2z-values) and dysfunction (SF < 0.26) was found to increase from 1.3% prior to pacemaker implantation to 13.4% (11/82 patients) at last follow-up (P = 0.01). Ten of these 11 patients had progressive LV remodelling and 8 of 11 were symptomatic. The only significant risk factor for the development of LV dilatation and dysfunction was the presence of epicardial RV free wall pacing (OR = 14.3, P < 0.001). Other pre-implantation demographic, diagnostic, and haemodynamic factors including block aetiology, pacing variables, and pacing duration did not show independent significance. Conclusion Right ventricular pacing leads to pathologic LV remodelling in a significant proportion of paediatric patients. The major independent risk factor is the presence of epicardial RV free wall pacing, which should be avoided whenever possible.

Hemodynamically optimized temporary cardiac pacing after surgery for congenital heart defects.

Disturbance of normal AV synchrony and dyssynchronous ventricular contraction may be deleterious in patients with otherwise compromised hemodynamics. This study evaluated the effect of hemodynamically optimized temporary dual chamber pacing in patients after surgery for congenital heart disease. Pacing was performed in 23 children aged 5 days to 7.7 years (median 7.3 months) with various postoperative dysrhythmias, low cardiac output, and/or high inotropic support and optimized to achieve the highest systolic and mean arterial pressures. The following four pacing modes were used: (1) AV synchronous or AV sequential pacing with individually optimized AV delay in 11 patients with first‐to third‐degree AV block; (2) AV sequential pacing using transesophageal atrial pacing in combination with a temporary DDD pacemaker for atrial tracking and ventricular pacing in three patients with third‐degree A V block and junctional ectopic tachycardia, respectively, who had poor signal and exit block on atrial epicardial pacing wires; (3) R wave synchronized atrial pacing in eight patients with junctional ectopic tachycardia and impaired antegrade AV conduction precluding the use of atrial overdrive pacing; (4) Atrio‐biventricular sequential pacing in two patients. Pressures measured during optimized pacing were compared to baseline values at underlying rhythm (13 patients with first‐degree AV block or junctional ectopic tachycardia) or during pacing modes commonly used in the given clinical situation: AAI pacing (1 patient with slow junctional rhythm and first‐degree AV block during atrial pacing), WI pacing (2 patients with third‐degree A V block and exit block and poor sensing on epicardial atrial pacing wires) and dual‐chamber pacing with AV delays set to 100 ms (atrial tracking) or 150 rns (AV sequential pacing) in 7 patients with second‐ to third‐degree A V block and functional atrial pacing wires. Optimized pacing led to a significant increase in arterial systolic (mean) pressure from 71.5 ± 12.5 (52.3 ± 9.0) to 80.5 ± 12.2 (59.7 ± 9.1) mmHg (P < 0.001 for both) and a decrease in central venous (left atrial) pressure from 12.3 ± 3.4 (10.5 ± 3.2) to 11.0 ± 3.0 (9.2 ± 2.7) mmHg (P < 0.001 and < 0.005, respectively). In conclusion, several techniques of individually optimized temporary dual chamber pacing leading to optimal AV synchrony and/or synchronous ventricular contraction were successfully used to improve hemodynamics in patients with heart failure and selected dysrhythmias after congenital heart surgery.

Congenital atresia of the left coronary artery – myocardial revascularization in two children

Two patients with congenital atresia of the left coronary artery ostium underwent myocardial revascularization at the age of three years and three months, respectively. The patients were admitted to the hospital with a clinical history of sudden chest pain or short apnea not necessitating resuscitation. Non-invasive examinations and hemodynamic studies revealed dysfunction of the left ventricle and ostial atresia of the left coronary artery. Surgical revascularization-bypass grafts were performed using the left internal mammary artery and saphenous vein graft in the first case and the left internal mammary artery in the second child. Both patients survived surgery and good patency of the grafts was confirmed by coronary angiograms during hospital stay. These cases are interesting because of their rarity and diagnostic and therapeutic difficulties.

Improved results after the primary repair of interrupted aortic arch: impact of a new management protocol with isolated cerebral perfusion.

OBJECTIVE The aim of this retrospective study was to analyse results and risk factors of death after the repair of the interrupted aortic arch, and to compare results obtained with the use of deep hypothermic circulatory arrest versus isolated cerebral perfusion. METHODS The primary repair of the interrupted aortic arch and associated heart lesions was performed in 50 consecutive patients. The median age was 5 days and the mean weight was 3.1+/-0.6 kg. The interrupted aortic arch was of type A in 12 (24%) patients, type B in 37 (74%) and type C in one (2%) patient. Ventricular septal defect was present in 48 (96%) patients, subaortic stenosis in 15 (30%), truncus arteriosus in 14 (28%), transposition of the great arteries in two (4%), aortopulmonary window in two (4%) and double-outlet right ventricle in one (2%). The surgery consisted of reconstruction of the aortic arch by direct anastomosis and repair of associated heart lesions. In 25 (50%) patients, aortic arch reconstruction was performed using hypothermic circulatory arrest (group I) and in 25 by isolated cerebral perfusion (group II). The duration of cardiopulmonary bypass, aortic cross-clamping and circulatory arrest or isolated cerebral perfusion was 191+/-46 min, 90+/-24 min and 40+/-14 min, respectively, in group I; and 194+/-39 min, 74+/-20 min and 31+/-6 min, respectively, in group II. RESULTS There were 10 (20%) deaths in this series, eight (32%) in group I and two (8%) in group II. Out of 12 patients operated before 1995, seven (58%) patients died; and out of 38 patients operated between 1995 and 2009, three (8%) patients died (p=0.008). By Cox multifactorial analysis, the earlier date of operation represented the only risk factor of death (p=0.037). Twelve (71%) survivors in group I and five (22%) survivors in group II required re-intervention, most often for subaortic stenosis, aortic arch obstruction or conduit obstruction. All patients remain in the New York Heart Association (NYHA) class I or II at median 12.6 years in group I, and 1.7 years in group II, respectively, after surgery. CONCLUSIONS Interrupted aortic arch can be repaired in neonates with a mortality of 5-10%. The results depend on experience. Isolated cerebral perfusion was joined with decreased mortality but it did not influence the occurrence of neurological complications.

Use of a Modified, Commercially Available Temporary Pacemaker for R Wave Synchronized Atrial Pacing in Postoperative Junctional Ectopic Tachycardia

JANOUS̆EK, J., et al.: Use of a Modified, Commercially Available Temporary Pacemaker for R Wave Synchronized Atrial Pacing in Postoperative Junctional Ectopic Tachycardia. Junctional ectopic tachycardia (JET) is a life‐threatening arrhythmia frequently seen after surgical correction of congenital heart defects. This study evaluates the use of a modified, commercially available temporary dual chamber pacemaker used to reestablish AV synchrony by R wave synchronized atrial pacing, a technique not routinely applied because of a lack of appropriate equipment. Ten consecutive children with postoperative JET (median maximum heart rate 185, range 130–240 beats/min) age 0.3–45 (median 5.2) months were studied. R wave synchronized atrial pacing was performed using the VAT mode with inverse connection of the pacing wires (effectively AVT mode), short postventricular atrial refractory period (100 ms), and long AV (effectively VA) delay. AV delay was adjusted to achieve maximum increase in arterial pressure by optimal AV resynchronization. Pacing was successfully applied in all patients for a median period of 29 (range 10–96) hours until tachycardia cessation and led to an immediate increase in systolic, mean, and pulse pressure by 8.9 ± 3.2 (P < 0.001), 8.1 ± 4.0 (P < 0.001) , and 11.9 ± 7.8% (P < 0.005) , respectively. Two patients developed pacemaker‐mediated tachycardia, which could be easily stopped by AV (effectively VA) delay prolongation. Atrial flutter was induced in one patient by asynchronous atrial pacing during the VAT (effectively AVT) mode and managed by overdrive pacing. In conclusion, R wave synchronized atrial pacing could be easily performed using a modified, commercially available temporary dual chamber pacemaker. Significant hemodynamic benefit was achieved due to optimal AV resynchronization at intrinsic heart rate and spontaneous ventricular activation sequence. R wave synchronized atrial pacing should be included in the standard management protocol of postoperative JET. (PACE 2003; 26[Pt. I]:579–586)

Acute right ventricular resynchronization improves haemodynamics in children after surgical repair of tetralogy of Fallot

Aims Right bundle branch block is associated with right ventricular (RV) electromechanical dyssynchrony, which may contribute to acute haemodynamic impairment after repair of tetralogy of Fallot (ToF). We sought to evaluate the effects of RV resynchronization on haemodynamics and tissue oxygenation during the first 24 h after surgery. Methods and results Arterial pressures, cardiac output, and tissue oxygenation were measured in 28 consecutive patients (median age 10.1 months) during baseline sinus rhythm with right bundle branch block and after RV resynchronization by atrial-triggered RV free wall pacing in complete fusion with spontaneous activation. Studied variables were compared in a crossover design in four 5-min intervals (baseline rhythm and stimulation, 2x each). Resynchronization reduced the QRS complex duration from median 110 to 70 ms (P < 0.001), increased significantly median arterial systolic, mean and pulse pressure, cardiac index, left ventricular maximum +dP/dT and decreased central venous pressure (P < 0.001 for all). Both cerebral and renal oxygenation improved (P < 0.001). Eleven of the 28 patients showed a clinically highly significant resynchronization effect defined as an increase in arterial pulse pressure of ≥ 10%. The q-RV interval (expressed as % of QRS duration) at the RV pacing site during baseline rhythm was the only predictor of resynchronization effect. Conclusions RV resynchronization carried short-term improvement of haemodynamics in children early after surgery for ToF and might be a useful non-pharmacologic adjunct to the management of haemodynamically compromised patients. Resynchronization effect was maximized when pacing from area of the latest RV activation.

Pulmonary Right Ventricular Resynchronization in Congenital Heart DiseaseCLINICAL PERSPECTIVE: Acute Improvement in Right Ventricular Mechanics and Contraction Efficiency

Background— Electromechanical discoordination may contribute to long-term pulmonary right ventricular (RV) dysfunction in patients after surgery for congenital heart disease. We sought to evaluate changes in RV function after temporary RV cardiac resynchronization therapy. Methods and Results— Twenty-five patients aged median 12.0 years after repair of tetralogy of Fallot and similar lesions were studied echocardiographically (n=23) and by cardiac catheterization (n=5) after primary repair (n=4) or after surgical RV revalvulation for significant pulmonary regurgitation (n=21). Temporary RV cardiac resynchronization therapy was applied in the presence of complete right bundle branch block by atrial-synchronized RV free wall pacing in complete fusion with spontaneous ventricular depolarization using temporary electrodes. The q-RV interval at the RV free wall pacing site (mean 77.2% of baseline QRS duration) confirmed pacing from a late activated RV area. RV cardiac resynchronization therapy carried significant decrease in QRS duration (P<0.001) along with elimination of the right bundle branch block QRS morphology, increase in RV filling time (P=0.002), pulmonary artery velocity time integral (P=0.006), and RV maximum +dP/dt (P<0.001), and decrease in RV index of myocardial performance (P=0.006). RV mechanical synchrony improved: septal-to-lateral RV mechanical delay decreased (P<0.001) and signs of RV dyssynchrony pattern were significantly abolished. RV systolic stretch fraction reflecting the ratio of myocardial stretching and contraction during systole diminished (P=0.001). Conclusions— In patients with congenital heart disease and right bundle branch block, RV cardiac resynchronization therapy carried multiple positive effects on RV mechanics, synchrony, and contraction efficiency.

Haemodynamic changes due to delayed sternal closure in newborns after surgery for congenital cardiac malformations.

BACKGROUND Delayed sternal closure is used to prevent low cardiac output syndrome in selected newborns shortly after cardiac surgery for congenital cardiac defects. Sternal closure itself often causes haemodynamic and ventilatory instability that cannot be entirely assessed by standard monitoring means. Therefore, we used transpulmonary thermodilution technique for an exact evaluation of the haemodynamic changes. PATIENTS AND METHODS Between April, 2006, and December, 2008, 23 neonates aged from 1 to 30 days, with a median of 7 days, and weighing from 1.9 to 4.2 kilograms, with a median of 3.25 kilograms, were studied after biventricular corrections. Residual intracardiac shunts were excluded by echocardiography. Haemodynamic and ventilatory parameters, along with those obtained by the transpulmonary thermodilution technique, were recorded before and immediately after the sternal closure, and then at 0.5, 1, 2, 6, 12, 24, and 48 hours. RESULTS Chest closure caused significant decrease in systolic arterial pressure from 80.04 +/- 11.48 to 69.48 +/- 9.63 mmHg (p < 0.001), cardiac index from [median (25th/75th centile)] 2.640 (2.355/2.950) to 2.070 (1.860/2.420) l/min/m2 (p < 0.001), stroke volume index from 18.50 (16.00/20.00) to 14.00 (11.00/17.00) ml/m2 (p < 0.001), and dynamic lung compliance from 2.45 (2.31/3.00) to 2.30 (2.14/2.77) ml/cmH2O (p = 0.007). Stroke volume variation increased from 14.00 (9.25/16.75) to 18.00 (15.00/21.00) % (p < 0.001). The oxygenation index transitorily increased from 2.50 (2.14/3.15) to 3.36 (2.63/4.29) (p < 0.001). Serum lactate decreased from 1.40 (1.12/2.27) to 1.0 (0.8/1.3)mmol/l, p < 0.001 in coincidence with a haemodynamic stabilisation at a later time after chest closure. Cardiopulmonary instability caused by the sternal closure necessitated therapeutic intervention in 18 of 23 patients (78.3%). CONCLUSION Delayed sternal closure causes a significant transitory decrease in stroke volume, cardiac output and arterial blood pressure. Also lung compliance and blood oxygenation are temporarily significantly compromised.

Slide Plasty of Trachea and Right Main Bronchus in a Newborn

Congenital stenosis of airways is a rare and possibly life-threatening congenital defect with difficult treatment and uncertain prognosis. In our report, we describe a rare case of a 1-month-old newborn with concomitant stenosis of trachea and main bronchus and its successful treatment using slide plasty.