This study was designed to evaluate the sensitivity of changes in myocardial carbon dioxide and oxygen tensions as indicators of regional myocardial ischemia and also to determine to what extent these changes can be related to changes in intramyocardial ST segment voltage. Changes in ST segment voltage recorded in unipolar epicardial electrodes proved to be a less-sensitive indicator of underlying myocardial ischemia than were changes in ST segment voltage recorded in unipolar intramyocardial electrodes. In 9 dogs, regional ischemia was produced by placing a variable constrictor on the left circumflex coronary artery; circumflex flow was monitored. Myocardial carbon dioxide and oxygen tensions were measured using a mass spectrometer. Unipolar electrograms were recorded using a multicontact plunge electrode. With progressive degrees of proximal stenosis, ranging from a critical stenosis, which is associated with a decrease in mean flow of less than 15%, to a severe stenosis associated with and 80% decrease, ST voltage increased 21 mv and carbon dioxide tension increased 84 mm Hg, but oxygen tension decreased only 7 mm Hg. The study suggests that increases in intramyocardial ST segment voltage, an index of myocardial ischemia, are associated with parallel increases in myocardial carbon dioxide tension, each providing a more sensitive quantitative correlate of regional myocardial ischemia than do decreases in oxygen tension. The local accumulation of carbon dioxide may be an important pathophysiological mechanism in myocardial ischemia.
Percutaneous transluminal angioplasty (PTA) was used successfully to treat coarctation restenosis in seven patients. The patients were 10 months to 17 years old at the time of the angioplasty, and the initial coarctation repair had been performed 10 months to 16½/2 years previously. PTA reduced the systolic pressure gradient across the coarctation from a mean of 58 mm Hg before the procedure to a mean of 13 mm Hg immediately after PTA. Follow-up has been from 1 to 14 months and indicates that the decrease in the systolic pressure gradient is persistent. Circulation 68, No. 5, 1087-1094, 1983 SURGICAL REPAIR of coarctation of the aorta has been performed since 1945. Recent reviews have indicated that there is a high incidence of recurrence of stenosis at the anastomotic site, particularly if the primary repair is performed in infancy. 1-8 If surgical correction is delayed into later childhood, there would be a risk of persistent hypertension, although the risk of recurrent stenosis would be lessened.9' '°T he mechanism of recurrence of stenosis at the coarctation site has been considered to be the result of one or more factors: (1) incomplete relief of the obstruction at the time of the initial repair, (2) incomplete resection of "abnormal" aortic tissue that may have a tendency to proliferate, (2) failure of the anastomotic site to grow, (4) thrombus formation on the suture line, and (5) MethodsClinical material. Seven patients underwent percutaneous transluminal balloon angioplasty for treatment of recurrent stenosis in the aorta at the site of previous coarctation repair. The presenting data for these seven patients before the balloon angioplasty are summarized in table 1. The seven patients were divided into four categories based on the type of primary repair performed.Coarctation restenosis (end-to-end anastomosis, three patients) Patient 1. An 1 1-year-old girl had been in congestive heart failure in infancy. When she was 6 months old, a cardiac catheterization revealed severe coarctation of the aorta with a patent ductus arteriosus (PDA). Intra-aortic pressures indicated a 50 mm Hg pressure gradient across the coarctation. At 9 months of age she had surgical resection of the coarctation with an end-toend anastomosis. Subsequently she was asymptomatic, and when followed up in the outpatient clinic she had normal arm blood pressures and a 20 mm Hg lower pressure in her legs. At 11 years old, she had evidence of upper-extremity hypertension with diminished femoral pulses.Patient 2. An 8-year-old boy had been in congestive heart failure in the neonatal period. When he was 11 days old, cardiac catheterization revealed severe coarctation of the aorta and PDA. When he was 12 days old the coarctation was resected and an end-to-end anastomosis was performed. After the surgical procedure he had persistent upper-extremity hypertension with decreased femoral pulses. When he was 8 years old, cardiac catheterization revealed a discrete recurrent coarctation of the aorta.Patient 3. An 8-year-old boy had congest...
Video assisted thoracic surgery can be utilized as an effective and safe method for the initial diagnostic evaluation and surgical management of stable patients with penetrating thoracic trauma.
Two hundred and forty-three patients were evaluated following total correction of tetralogy of Fallot with special emphasis on postoperative conduction disturbances and on the occurrence of sudden death. The average follow-up period was 12 years with a range of 6 1/2 to 16 1/2 years. Sudden death occurred in seven patients. Four deaths were among those with right bundle branch block pattern (RBBB) and three of the four had premature ventricular contractions (PVC) for more than one month postoperatively. PVCs were documented in ten of the 158 patients with RBBB; sudden death occurred in three (30%). Three of the ten (30%) patients with trifascicular block pattern (TB) died suddenly, while no deaths occurred in 24 patients with bifascicular block pattern (BB). Progression of RBBB to BB and TB occurred in 18 patients from one month to seven years postoperatively (58% of BB and 40% of TB). The risk of sudden death in patients with RBBB and PVCs following tetralogy repair is high and warrants consideration of suppressive therapy. TB also carries a high risk. The finding that RBBB may progress to BB or TB mandates long-term careful follow-up of all tetralogy patients with postoperative conduction disturbances.
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