Stress-induced ventricular arrhythmia after repair of tetralogy of fallot

The combination of ventricular arrhythmias found on routine electrocardiography at rest and elevated right ventricular pressures may be associated with sudden death in patients after repair of tetralogy of Fallot. In this study data were reviewed from 104 patients who underwent treadmill exercise testing with a modified Bruce protocol at a mean age of 13.8 years, an average of 7 years after repair of tetralogy of Fallot. The frequency and form of ventricular arrhythmias as manifested in an electrocardiogram at rest as well as before, during and after treadmill exercise tests were tabulated for each patient. Cardiac catheterizatlon was performed within 1 week of the treadmill test in 82 of the 104 patients and the right ventricular systolic pressure, right ventricular end-diastolic pressure, pulmonary arterial systolic pressure and pulmonary to systemic flow ($\text{Qp}\text{Qs}$) ratio were compared in patients with and without ventricular arrhythmias. In 15 (14 percent) of the 104 patients, ventricular arrhythmia was evident in the electrocardiogram at rest and in 31 (30 percent) it was induced by treadmill exercise; 5 of the 15 with arrhythmia at rest had no arrhythmia during exercise. Compared with the remaining 73 patients, the 31 patients who had ventricular arrhythmias during treadmill testing (1) were older (16.2 versus 12.8 years, p < 0.01, t test) and were tested at a longer interval after repair of tetralogy of Fallot, (2) had greater right ventricular systolic pressure (52.7 versus 41.3 mm Hg, p < 0.005), (3) had greater right ventricular end-diastolic pressure (8.0 versus 6.1 mm Hg, p < 0.001), and (4) had no difference in pulmonary arterial systolic pressure or $\text{Qp}\text{Qs}$ ratio. Uniform premature ventricular complexes were found in 28 patients, multiform premature ventricular complexes in two and ventricular tachycardia in one. Patients whose ventricular arrhythmia appeared with exercise had similar hemodynamic findings to-those whose arrhythmia disappeared with exercise. Two patients, each with elevated right ventricular systolic pressure and multiform premature ventricular complexes, had cardiac arrest at home.It is concluded that (1) treadmill exercise testing is a sensitive method for detecting ventricular arrhythmia in patients after repair of tetralogy of Fallot; (2) ventricular arrhythmia during treadmill exercise is related to abnormal hemodynamic status; (3) multiform premature ventricular complexes, couplets or ventricular tachycardia with exercise testing are highly associated with abnormal hemodynamic status and sudden death; (4) suppression of ventricular arrhythmia with exercise is neither the characteristic nor necessarily the benign response in these patients; and (5) ventricular arrhythmia may be a late developing phenomenon and may increase with longer postoperative intervals. Patients after repair of tetralogy of Fallot should be treated for ventricular arrhythmia detected in the electrocardiogram at rest or during treadmill exercise testing.     

Rhabdomyolysis in thyroid storm

This is the first reported case of thyroid storm complicated by rhabdomyolysis with acute reversible renal failure. The only possible causes for the rhabdomyolysis were inherent features of thyroid storm. Although hyperthyroid patients characteristically have normal or low serum levels of muscle enzymes, this case report demonstrates that rhabdomyolysis with elevated serum levels of muscle enzymes can occur with hyperthyroidism. An appreciation of the potential for rhabdomyolysis in hyperthyroidism should facilitate prompt initiation of aggressive therapy for myoglobinuria and thereby limit the severity of acute renal failure in these already very sick patients.     

Isolated stenosis of left anterior descending or right coronary artery: Relation between site of stenosis and ventricular dysfunction and therapeutic implications

Indications for coronary arterial bypass surgery in single vessel coronary artery disease are unresolved. To determine the extent of myocardium at risk with stenosis (70 percent or more) of a single coronary artery, left ventricular angiograms of 200 patients with stenosis confined to either the left anterior descending or right coronary artery and of 15 normal control subjects were assessed. Among patients without myocardial infarction, ejection fraction was unchanged (p > 0.05 versus normal values) in (1) those with stenosis of the proximal (above first septal branch, n = 19), mid (between septal and first diagonal branches, n = 14) and distal (within 2 cm distal to diagonal branch, n = 15) left anterior descending coronary artery, and (2) those with stenosis of the proximal (above acute marginal branch, n = 16) and distal (between acute marginal and posterior descending branches, n = 16) right coronary artery. In contrast, ejection fraction was depressed (p < 0.001 versus normal values) In left anterior descending arterial stenosis with anterior myocardial Infarction: proximal (38 ± 10 percent, n = 33), mid (46 ± 12 percent, n = 24; p < 0.01 versus proximal), and distal (56 ± 9 percent, n = 15; p < 0.01 versus mid). Ejection fraction was similar with proximal and distal stenosis of the right coronary artery and inferior Infarction: 54 ± 11 percent versus 55 ± 9 percent, p > 0.05; both p < 0.05 versus normal value. Shortening velocity was assessed in three anterior (I to III, base to apex) and three inferior (IV to VI, apex to base) equidistant hemichords perpendicular to the long axis, 30 ° right anterior oblique view. With anterior Infarction and left anterior descending stenosis, shortening of hemichords I to V, I to IV and II to III with proximal, mid and distal stenosis, respectively, was depressed (p < 0.05 versus normal value). Septal excursion and thickening on M mode echocardiography with proximal left anterior descending stenosis and infarction were depressed (p < 0.05 versus mid and distal stenosis with infarcts). Hemichordal shortening with Inferior infarction was similarly depressed (p > 0.05) with proximal and distal stenoses.In conclusion, stenosis of the left anterior descending coronary artery is a heterogenous disease, the extent of jeopardized myocardium is highly dependent on the site of stenosis, and the criteria for surgery cannot be applied uniformly. When the surgical goal is myocardial preservation, these data provide an objective rationale for bypass of stenosis of the proximal left anterior descending coronary artery. In stenosis confined to the right coronary artery, left ventricular preservation alone should not be considered an indication for coronary bypass grafting.     

Echocardiographic pulsed doppler features of absent pulmonary valve syndrome in the neonate

M mode echocardiography was used to evaluate nine neonates with absent pulmonary valve syndrome. Six were also studied with two dimensional echocardiography and two with pulsed Doppler echocardiography. M mode echocardiography demonstrated a large, overriding great artery and right ventricular dilation in all nine patients and abnormal septal motion in eight. Two dimensional echocardiography demonstrated aneurysmal dilation of the main pulmonary artery in all six patients studied. Pulsed Doppler echocardiography in the two infants studied demonstrated anterograde systolic and retrograde diastolic flow in the main pulmonary artery and right ventricular outflow tract. The echocardiographic features of absent pulmonary valve syndrome appear to be unique and allow the diagnosis to be made noninvasively, thus obviating or delaying the need for potentially high risk cardiac catheterization.     

Atrioventricular valve abnormalities in infancy: two-dimensional echocardiographic and angiocardiographic comparison

The results of two-dimensional echocardiography and biplane angiocardiography from 47 infants with congenital atrioventricular (AV) valve abnormalities were compared. Eleven patients had atresia of the right AV valve, 10 had atresia of the left AV valve, 4 had hypoplasia of the right AV valve and 5 had hypoplasia of the left AV valve. Twelve patients had endocardial cushion defect, three had single ventricle and two had straddling of the left AV valve. There was agreement between the two techniques as to the number of AV valves present in each patient. The echocardiographic estimate of valve anular diameter was below normal in seven of the eight patients thought to have a hypoplastic anulus by angiocardiography. In 10 of the 12 patients with endocardial cushion defect, there was agreement between the two techniques as to the presence or absence of atrial and ventricular septal defect. The chordal attachments of straddling valves were better visualized by echocardiography; flow patterns and effective orifice size were better demonstrated by angiocardiography. The subcostal four chamber echocardiographic views and cranially angulated oblique angiocardiographic views were comparable and provided the best images for determination of the size and number of AV valves and their relation to the atrial and ventricular septa.     

Control of late postoperative ventricular arrhythmias with phenytoin in young patients

Ventricular arrhythmias probably initiate the events leading to sudden death in patients who have recovered uneventfully from surgery for congenital heart disease. It is therefore recommended that antiarrhythmic therapy be given to all patients who have had surgery for congenital heart defects and who have ventricular arrhythmias found in a routine electrocardiogram taken after the immediate postoperative period. The response of ventricular arrhythmias to treatment was studied in six ambulatory patients aged 7 to 27 years (mean 16.5) who had had surgery a mean of 10.7 years before the arrhythmia was recognized. Four patients had unsatisfactory repair of the congenital defect; the two other patients had only a palliative operation. Each patient's electrocardiogram was monitored continually by tape recording. Each received phenytoin, 3.75 mg/kg body weight, every 6 hours for four doses, then 1.9 mg/kg every 6 hours until the serum concentration of phenytoin was 15 to 20 μg/ml. This serum concentration was maintained with the daily administration of 2.5 to 3 mg/kg every 12 hours. In the 24 hours before treatment, two patients had ventricular tachycardia, two had paired premature ventricular complexes and two had 10 or more single premature ventricular complexes/hour. After treatment, all patients had “effective control” (one or less premature ventricular complex/hour for 12 consecutive hours). This control was achieved with phenytoin in five patients, but one patient required the addition of disopyramide (2 mg/kg every 6 hours). All five patients undergoing a treadmill test before treatment had premature ventricular complexes during or after exercise; after treatment, only one had premature ventricular complexes after exercise. The patient who required two drugs was unable to perform a treadmill test. The mean effective serum phenytoin concentration, 15.7 μg/ml (range 8.5 to 20.0), was reached at a mean time of 61.2 hours (range 42 to 80) after the start of phenytoin therapy. Ataxia occurred in two patients with serum phenytoin concentrations of 16 and 20 μg, but not in the other four, three of whom had serum concentrations greater than 20 μg/ml. Echocardiographic, hematopoletic, hepatic and renal function indexes remained constant with treatment.It is concluded that (1) phenytoin suppressed ventricular arrhythmias in six children and young adults after surgery for congenital heart disease; (2) the effective serum concentration of phenytoin was approximately 15 μg/ml, but varied widely; and (3) this concentration was achieved within 48 to 72 hours when an oral loading dose was administered.