Carotid artery Doppler flow pattern after deep hypothermic circulatory arrest in neonatal piglets.

The mechanisms of cerebral injury after cardiac surgery in neonates are not clear. The aim of the study was the analysis of flow changes in the carotid artery of neonatal piglets after deep hypothermic circulatory arrest (DHCA). Eight neonatal piglets were connected to cardiopulmonary bypass (CPB) and underwent (i) cooling to 18°C core temperature within 30 min, (ii) DHCA for 90 min, and finally (iii) rewarming to 37°C after cross-clamp release (60 min of reperfusion). The blood flow was measured in the left carotid artery by an ultrasonic flow probe before CPB (baseline; T0 ), immediately after termination of reperfusion on CPB (T1 ), 30 min later (T2 ), and 60 min later (T3 ). Additionally, the pulsatility index and the resistance index were calculated and compared. Finally, the relationship between the carotid artery flow and the corresponding pressure at each time-point was compared. After termination of CPB (T1 ), the mean carotid artery flow was reduced from 45.26 ± 2.58 mL/min at baseline to 23.29 ± 2.58 mL/min (P < 0.001) and remained reduced 30 and 60 min later (P < 0.001 vs. baseline). Both the pulsatility index and the resistance index were increased after termination of reperfusion, with the maximum occurring 30 min after CPB end. In conclusion, the carotid artery Doppler flow in neonatal piglets was reduced after DHCA, while the indices of pulsatility and resistance increased.

Aortic surgery after previous procedure of congenital aortic stenosis.

Irrespective of previous procedure in congenital aortic stenosis, aortic surgery later in life may be indicated. The aim of the present study was the analysis of indications, risks, and outcomes of aortic surgery after previous aortic valve procedure. The data of patients who underwent aortic surgery after previous treatment of congenital aortic stenosis in a 10-year period (from 2000 to 2009) were retrospectively analyzed. Thirty-two patients (23 male and 9 female) underwent redo aortic surgery. The mean age at surgery was 13.5 ± 11.3 years. Seventeen patients had undergone initial aortic balloon valvuloplasty (BVP) and 15 patients open commissurotomy (COM). Nine cases had undergone the primary procedure at neonatal age and two patients had undergone cardiac surgery before the initial aortic valve procedure. Seven of the patients with previous COM (43.8%) had undergone concomitant surgery along with initial commissurotomy. A reintervention within the first year after the primary procedure was performed in seven patients (seven after BVP and none after COM; P < 0.05). The interval between the last intervention and the first redo aortic surgery was 7.5 ± 9.5 years (3.1 ± 3.5 years after BVP vs. 12.5 ± 11.7 years after COM; P < 0.05). A second redo surgery was performed in nine patients (four after initial BVP and five after COM). Congenital aortic stenosis is very often presented in combination with additional pathologies. These concomitant diseases along with the underlying disease give the indication for reoperation. Reinterventions are more often indicated after primary BVP. Long follow-up in specialized centers is mandatory.

Carotid Doppler flow after cardiopulmonary bypass and mild hypothermia in neonatal piglets.

Although the mechanisms of neurological disorders after cardiac surgery in neonates are still not fully understood, alterations in blood flow after cardiopulmonary bypass (CPB) may lead to cerebral injury. The aim of the study was the analysis of flow changes in the carotid artery of neonatal piglets after CPB. Ten neonatal piglets (younger than 7 days) were connected to the CPB and further management underwent three steps: (i) cooling to 32°C core temperature within 30 min; (ii) cardiac arrest under cardioplegic myocardial protection for 90 min; and (iii) rewarming to 37°C after cross-clamp release (60 min of reperfusion). In summary, piglets were separated from CPB after a total duration time of 180 min. The blood flow was measured in the left carotid artery by an ultrasonic flow probe before CPB (baseline), immediately after CPB, 30 min, and 60 min after CPB. Additionally, the pulsatility index and the resistance index were calculated and compared. Finally, the relation of the carotid artery flow data with the corresponding pressure data at each time point was compared. After termination of CPB, the carotid artery mean flow was reduced from 28.34 ± 13.79 mL/min at baseline to 20.91 ± 10.61 mL/min and remained reduced 30 and 60 min after CPB termination (19.71 ± 11.11 and 17.64 ± 15.31 mL/min, respectively). Both the pulsatility and the resistance index were reduced immediately after CPB termination and increased thereafter. Nevertheless, values did not reach statistical significance. In conclusion, the carotid Doppler flow immediately after CPB and mild hypothermia in neonatal piglets was lower than before CPB due to reduced vascular resistance. Additionally, the pressure-flow relation revealed that immediately after CPB, a higher pressure is required to obtain adequate flow.

Myocardial contractility and relaxation after deep hypothermic circulatory arrest in a neonatal piglet model.

Cooling before circulatory arrest or ischemic arrest has been reported to influence myocardial performance in isolated neonatal hearts. The aim of the present study was to analyze indices of myocardial contractility and relaxation in an in vivo neonatal model after deep hypothermic circulatory arrest (DHCA). DHCA (18°C; DHCA group; n = 8) or mild hypothermic cardiopulmonary bypass ([MH-CPB] 32°C; MH-CPB group; n = 10) was applied in newborn piglets. After reperfusion (60 and 120 min), left ventricular dP/dt(max) increased in DHCA and MH-CPB, while-dP/dt(max) decreased slightly in DHCA and increased in MH-CPB. Nevertheless, the differences between the two groups did not reach statistical significance. In conclusion, left ventricular contractility remained stable after reperfusion following DHCA, to some degree at the expense of the diastolic function.

Myocardial contractile function in survived neonatal piglets after cardiopulmonary bypass.

BACKGROUND: Hemodynamic function may be depressed in the early postoperative stages after cardiac surgery. The aim of this study was the analysis of the myocardial contractility in neonates after cardiopulmonary bypass (CPB) and mild hypothermia. METHODS: Three indices of left ventricular myocardial contractile function (dP/dt, (dP/dt)/P, and wall thickening) were studied up to 6 hours after CPB in neonatal piglets (CPB group; n = 4). The contractility data were analysed and then compared to the data of newborn piglets who also underwent median thoracotomy and instrumentation for the same time intervals but without CPB (non-CPB group; n = 3). RESULTS: Left ventricular dP/dtmax and (dP/dtmax)/P remained stable in CPB group, while dP/dtmax decreased in non-CPB group 5 hours postoperatively (1761 ± 205 mmHg/s at baseline vs. 1170 ± 205 mmHg/s after 5 h; p < 0.05). However, with regard to dP/dtmax and (dP/dtmax)/P there were no statistically significant differences between the two groups. Comparably, although myocardial thickening decreased in the non-CPB group the differences between the two groups were not statistically significant. CONCLUSIONS: The myocardial contractile function in survived neonatal piglets remained stable 6 hours after cardiopulmonary bypass and mild hypothermia probably due to regional hypercontractility.

Reoperations in adults after correction of tetralogy of Fallot.

Adults with congenital heart diseases are an increasing patient population. Since the first successful palliative procedure in 1945 (Blalock and Tausing, JAMA 128: 189-194, 1945) and first corrective operation in 1955 (Lillehei et al., Ann Surg 142: 418, 1955) patients with Tetralogy of Fallot, which is the most common cyanotic CHD, have had excellent long term results and good quality of life. Over the long term, these patients are under risk of sudden death because of arrhythmias and congestive heart disease caused by tricuspid regurgitation, pulmonary regurgitation, ventricular septal defect, right ventricular outflow tract obstruction.