Abnormalities of conduction after total correction of Fallot's tetralogy: a prospective study

To determine the frequency of post-operative conduction abnormalities in Pakistani patients undergoing total correction for Fallot's Tetralogy.

One hundred and fifteen patients of Fallot's Tetralogy underwent definitive repair between January, 1999 and April, 2000. Their mean age was 12.89 years (range 3-30 years). One hundred nine patients (94.78%) had severe cyanosis and 6 patients (5.21%) were moderately cyanotic due to mild right ventricular outflow tract (RVOT) obstruction. Thirty percent patients required frequent hospital admissions within 6 months before the time of operation due to -hyper-cyanotic spells. The mean haematocrit was 50.83 (range 28-71). The majority of patients were in NYHA class-III (57%) and 45% had previous palliative shunt procedures done. Surgical access was through the RVOT in 90% cases and trans-atrial in 10%. RVOT patch was used in 55.9%, Pulmonary artery patch in 13.5% and trans-annular patch in 17.1% of cases.

The mean bypass time was 79.15 min and the mean cross clamp time 51.23 min. Average stay in the intensive care unit was 4.48 days. Twenty-three patients required re-exploration for bleeding. Sixty-nine patients required inotropic support. Fifteen patients had transient heart blocks and two had complete heart block requiring permanent pace-maker. Nineteen patients had various transient arrhythmias which were managed medically. Univariate analysis showed that higher age at operation, low preoperative heart rate, prolonged bypass time, prolonged cross clamp time and presence of patch on pulmonary artery were more common in patients who developed various heart blocks. However, none of these factors had statistical significance or definitive cause-effect relationship with heart blocks.

With careful surgical technique, total correction of Fallot's tetralogy can be conducted in children and young adults, with a very low risk of conduction abnormalities.