Biomedical subjects
Publications and source records attributed to J E Morch.
A patient with tetralogy of Fallot who presented at 58 years of age is described. Following surgical intracardiac repair he had 20 years of improved functional capacity. Though such surgery is now usually performed in infancy, the literature indicates that surgical correction of tetralogy of Fallot in appropriate adults is associated with low mortality and good long-term results.
BACKGROUND: Medical treatment of the elderly is changing to include the aggressive management of coronary artery disease with percutaneous transluminal coronary angioplasty. OBJECTIVE: The purpose of this study was to review major hospital events of patients aged 70 years or more, who underwent a first percutaneous transluminal coronary angioplasty. METHODS: A retrospective medical record review was done of 246 consecutive patients of 70 years or more, from January 1985 to December 1988, at a tertiary care community hospital. Adverse events and the factors that influenced outcome were identified. RESULTS: Of 246 patients (age range, 70-85 years, mean = 73.6), 19 died, 4 had a cerebral vascular accident, 11 had a transfusion and 11 underwent coronary artery bypass grafting. Sixteen patients had acute vessel closure and 8 died. Twenty-five patients had one event and 21 patients had more than one. DISCUSSION: The event rate after percutaneous transluminal coronary angioplasty in the elderly is high. CONCLUSIONS: Knowledge of the factors that influence adverse events (diagnostic category, success of procedure, degree of coronary artery disease and age) will assist the critical care team to plan and implement appropriate care.
Left ventricular function at rest and during supine bicycle exercise was assessed by gated radionuclide angiography in 20 diabetic patients and 18 normal control subjects without clinical evidence of heart disease. The diabetic patients were aged 21 to 44 years and all except one used insulin. No subject developed chest pain or electrocardiographic changes during exercise. Both groups had a similar rest and exercise heart rate and blood pressure, and both achieved similar work loads. The control group had an ejection fraction at rest of 65.4 +/- 6.2% (mean +/- SD) and only 1 of 18 showed a decrease with exercise; peak exercise ejection fraction averaged 77.1 +/- 7.8%. The diabetic group had a mean ejection fraction at rest of 63.7 +/- 6.5%, similar to that of the control group, but 7 of 20 showed a decrease during exercise; the exercise ejection fraction averaged 67.7 +/- 9.7%, significantly lower than that of the control group (p less than 0.01). The diabetic patients varied widely in ejection fraction response to exercise, ranging from an increase of 25% to a decrease of 21%. This response did not correlate with age, sex, duration of diabetes, smoking, retinopathy, exercise heart rate, blood pressure or rate-pressure product, work load attained or ejection fraction at rest. These data suggest that approximately one-third of patients with diabetes have subclinical left ventricular dysfunction without correlation to risk factors for atherosclerosis or other diabetic complications. Whether this is due to unrecognized coronary artery disease or primary myocardial disease remains unknown.
Rest and exercise right and left ventricular function were compared using equilibrium gated radionuclide angiography in 19 normal sedentary control subjects (mean age 28 years, range 22 to 34) and 34 patients with hemodynamically documented congenital ventricular septal defect (VSD) (mean age 27 years, range 20 to 40). The 34 patients with VSD were divided into 3 groups: those in Group 1 (17 patients) had pulmonary to systemic blood flow ratios of less than 2 to 1; those in Group 2 (12 patients) had prior surgical closure of VSD (mean interval from surgery 17 years, range 9 to 22), and those in Group 3 (5 patients) had Eisenmenger's complex. Gated radionuclide angiography was performed at rest and during each level of graded supine bicycle exercise to fatigue. Heart rate, blood pressure, maximal work load achieved, and right and left ventricular ejection fractions were assessed. The control subjects demonstrated an increase in both the left and right ventricular ejection fractions with exercise (0.70 +/- 0.07 to 0.79 +/- 0.05 and 0.46 +/- 0.06 to 0.57 +/- 0.04; p less than 0.001 for left and right ventricles, respectively). All study groups failed to demonstrate an increase in ejection fraction in either ventricle with exercise. Furthermore, resting left ventricular ejection fraction in Groups 2 and 3 was lower than that in the control subjects (0.59 +/- 0.09 and 0.54 +/- 0.06 versus 0.70 +/- 0.07; p less than 0.001) and resting right ventricular ejection fraction was lower in Group 3 versus control subjects (0.30 +/- 0.07 versus 0.46 +/- 0.06; p less than 0.001). Thus (1) left and right ventricular function on exercise were abnormal in patients with residual VSD as compared with control subjects; (2) rest and exercise left ventricular ejection fractions remained abnormal despite surgical closure of VSD in the remote past; (3) resting left and right ventricular function was abnormal in patients with Eisenmenger's complex; (4) lifelong volume overload may be detrimental to myocardial function.
A case report details the operative technique used in the repair of complete transposition of the great arteries (TGA), ventricular septal defect (VSD), and pulmonary stenosis in a patient who had had Baffes procedure previously. Experience in managing 10 patients with complete TGA who had undergone a Baffes procedure is discussed. Four patients with a large VSD had pulmonary vascular disease. The condition of 1 of them was improved by a palliative Mustard operation. Four children with isolated TGA underwent a successful modified Mustard repair. The 2 remaining patients had a VSD and pulmonary stenosis; in 1 the condition was palliated by a Glenn shunt. The other is the subject of the case report. The mean interval between the Baffes procedure and the second operation was 11 years. There was 1 late death after secondary repair. Follow-up in the remaining 6 patients at a mean of 10.6 years indicates a favorable outcome.
Serial ECG's were reviewed in 93 consecutive patients who were proven to be susceptible to malignant hyperthermia by caffeine contracture and ATP depletion tests on skeletal muscle biopsies, but who were without a history of pyrexic crises. There were 46 males and 47 females with a mean age of 33 years. Abnormal ECG's were found in 26 of the patients, with conduction defects in 14, repolarization abnormalities (non-specific ST-T changes) or "Q" waves in nine and increased voltages suggesting left ventricular hypertrophy in three (in the absence of hypertension). An abnormal ECG in a young patient may reflect malignant hyperthermia susceptibility.
Left ventricular function was compared in 18 normal sedentary controls (mean age 28 years, range 22 - 34 years) and nine endurance-trained athletes (mean age 19 years, range 15 - 25 years) at rest and during supine bicycle exercise. Gated radionuclide angiocardiograms were performed at rest and at each level of graded maximal supine bicycle exercise. Heart rate, blood pressure, left ventricular ejection fraction and the relative changes in left ventricular end-diastolic and end-systolic volumes were assessed. Athletes attained a much greater work load than controls (mean 22.1 kpm/kg body weight vs 13 kpm/Kg body weight). Both groups achieved similar increased in heart rate, blood pressure and ejection fractions. In the controls, the mean end-diastolic volume increased to 124% of that at rest (p less than 0.02) during exercise and the mean end-systolic volume decreased to 81% of the rest level (p less than 0.02). In contrast, the mean end-diastolic volume did not significantly change during exercise in the athletes, and the mean end-systolic volume decreased to 64% of rest (p less than 0.05). Thus, although trained and untrained healthy subjects had similar increases in the left ventricular ejection fraction during exercise, different mechanisms were used to achieve these increases. Untrained subjects increased end-diastolic volumes, whereas trained subjects decreased the end-systolic volumes. The ability of athletes to exercise without increasing preload may be an effect of training amd might have important implications in reducing myocardial oxygen demand during exercise.
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Thirty-five patients with atrioventricular (AV) discordance underwent repair of major intracardiac defects. Ventricular septal defect (VSD) was the most frequently encountered lesion, present alone or in combination with other lesions in 86% of these patients. Pulmonary stenosis (51%) and tricuspid insufficiency (37%) were the other lesions encountered. The initial operative mortality of 8.6% is approaching that for these same defects when repaired in the patient with normal atrioventricular connections. However, the late mortality of 19% with an average follow-up of 4.4 years is higher than expected in the absence of AV discordance. Reoperation for residual or recurrent defects was required in 9 of the 32 survivors and was associated with a mortality of 33%. Seven of the 9 reoperations were required for tricuspid valve dysfunction. Elective repair of major anomalies in association with AV discordance can be accomplished safely, but these patients require careful long-term follow-up in anticipation of late problems.
Eighteen patients with Prinzmetal's angina were studied angiographically and 17 were followed for an average of 27 months. The were 12 men and six women, with a mean age of 46.3 years. The mean duration of symptoms before clinical diagnosis was 4.1 weeks. Four had had a previous myocardial infarction. Six patients had spontaneous cardiac arrests within 48 hours of diagnosis and hospital admission. At coronary arteriography, 10 patients had significant coronary artery disease; two of these had coronary artery spasm. The remaining eight patients had normal cornary arteries with significant coronary artery spasm at arteriography. Angiographic mitral valve prolapse was found in eight patients; seven of these had inferior ST segment elevation with pain. Six of the 10 patients with significant coronary artery disease had aortocoronary bypasses performed with good results. Ten of the remaining 11 patients who were treated medically had their symptoms controlled with oral isosorbide dinitrate alone or in combination with propranolol, nifedipine or perhexiline but propranolol may have an adverse effect. Though the initial clinical course in untreated patients was unfavourable, progress after starting treatment was good, with no further cardiac arrests, myocardial infarctions, or deaths.
Long-term follow-up of aortocoronary bypass has shown good preservation of ventricular function. However, myocardial reserve in the immediate postoperative period may not be optimal. Nineteen patients who underwent elective aortocoronary bypass protected with cold potassium cardioplegia were studied in the early postoperative period at rest and during the stress of atrial and ventricular pacing. Performance was assessed by hemodynamic, metabolic and nuclear angiographic measurements. In the first 2--6 hours after aortic cross clamping, myocardial performance was preserved at rest and there was no evidence of ischemic metabolism. Atrial pacing at a rate of 119 beats/min caused a significant increase in cardiac index (p less than 0.01) without deterioration in hemodynamics, ejection fraction or metabolic status. At the same rate, ventricular pacing did not change the cardiac index and there was a decrease in hemodynamic function. Ejection fraction decreased from 56% to 44% (p less than 0.05) without a change in end-diastolic volume. Lactate, pyruvate and beta hydroxybutyrate extractions were changed to net production. Ventricular performance was preserved at rest immediately after aortocoronary bypass done with multidose cold potassium cardioplegia, with adequate reserve to meet the stress of atrial but not ventricular pacing. We conclude that the therapeutic implications of the type of pacing selected in the immediate postoperative period may be important.
Cardiomyopathy develops in some individuals who have a susceptibility to malignant hyperthermia. We studied right ventricular endomyocardial biopsy specimens from nine patients defined as having this disorder because of positive caffeine contracture tests on skeletal muscle biopsy specimens. Three patients had clinical evidence of cardiomyopathy and six did not. Light microscopy showed cytoplasmic contraction bands, perinuclear clearing, and a mild to moderate variation in myocyte and nuclear size. Ultrastructurally cytoplasmic contraction bands were associated with cardiac villi, myofiberlysis, and myofibrillolysis. These changes and occasional breaks in the sarcolemma were regarded as artefacts of the biopsy procedure. Megamitochondriosis with accompanying degenerative changes in the mitochondria were also seen and probably indicate increased cell metabolism; vacuolation of the cytoplasm was regarded as an "aging" phenomenon. Thus, the biopsy specimens were abnormal, but the changes were artefactual or nonspecific and were not unique to this group of patients. Biopsy did not provide a morphological explanation for abnormal cardiac function.
The effect on myocardial perfusion distribution of intracoronary glyceryl trinitrate in a dose (60 micrograms) insufficient to cause alterations in systemic blood pressure or heart rate was studied in eight patients with angiographically demonstrated collaterals from the left coronary system to the distal right coronary artery. Double isotope imaging using technetium-99m and iodine-131 labelled albumin macroaggregates allowed each patient to serve as his own control. The reproducibility of the imaging and data handling techniques was shown in 12 control patients. Glyceryl trinitrate caused a significant diminution in the collateral-mediated fractional perfusion while increasing that of the native coronary bed.
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Myocardial perfusion imaging with thallium-201 and electrocardiography with the subject at rest and undergoing submaximal treadmill exercise were performed in 19 men and 3 women. Selective coronary arteriography and left ventriculography showed that 7 had normal coronary arteries and 15 had coronary artery disease.The 11 persons with electrocardiographic evidence of an old myocardial infarct (q waves) had a perfusion defect at rest in the area of the infarct and a segmental abnormality of wall motion apparent on the left ventriculogram corresponding to the perfusion defect.MYOCARDIAL PERFUSION IMAGING AND ELECTROCARDIOGRAPHY WERE EQUALLY SENSITIVE IN DETECTING CORONARY ARTERY DISEASE IN EXERCISING INDIVIDUALS: perfusion defects were noted in 7 of the 15 persons with coronary artery disease, and diagnostic ST-segment depression was present in 8 of the 15. Combination of the results of the two tests with exercise permitted the identification of 11 of the 15 persons and improved the sensitivity. Combination of the results of rest and exercise imaging and electrocardiography permitted the identification of 94% of the patients with coronary artery disease.Myocardial perfusion imaging with (201)TI in the subject at rest is a sensitive indicator of previous myocardial infarction. Imaging after the subject has exercised is a useful adjunct to conventional exercise electrocardiography, especially in those whose exercise electrocardiogram is non-interpretable.
Technetium-99m stannous pyrophosphate scintiscanning was performed in 22 patients with radiographically detected calcification within the cardiac silhouette. All but one of these scintigrams showed a localised area of increased activity similar to that ordinarily seen in acute myocardial infarction. Scintiscans in 3 patients after removal of the calcified aortic valve reverted to negative. It was concluded that this technique for acute infarct detection may yield false positive results in the presence of cardiac calcification.
Malignant hyperthermia is a disease resulting from defective cellular membranes, usually presenting as drug-induced pyrexic crises. We describe four patients with life threatening ventricular arrhythmias or chest pain in the absence of pyrexic crises. Three presented with life threatening arrhythmias and the fourth with severe atypical chest pain. Two patients had a family history of multiple sudden deaths. Resting CKs were elevated in three patients while CK-MB was elevated in one. Resting ECGs were abnormal in three. Three patients had recurrent ventricular tachycardia, two had recurrent ventricular fibrillation and multiple cardiac arrests. Cardiac catheterization showed abnormal left ventricular wall motion in two and minimal mitral valve prolapse in one while all had normal coronary arteries. Thallium-201 myocardial imaging demonstrated large perfusion defects in the patient with electrocardiographic Q waves and normal coronary arteries. Myocardial involvement has been demonstrated by clinical, electrocardiographic, hemodynamic, angiographic and myocardial imaging abnormalities. Malignant arrhythmias occurred in these patients in the absence of pyrexic crises or drug admininstration. Abnormal calcium release in the myocardium, as documented in skeletal muscle membranes, may be a unifying concept for the various manifestations described.
The influence of smoking, hyperlipidemia, and glucose intolerance on graft patency and rate of progression of obstructive disease in the native circulation was assessed in 99 patients 1 1/2 years after aortocoronary bypass grafting. There were 24 patients in whom none of these risk factors was identified. There were 42 patients with one, 29 with two, and four with three risk factors. Overall graft patency rate was 74%. Graft patency was not significantly influenced by any of these factors either singly or in combination. Progression of obstructive disease in both proximal and distal segments of grafted vessels and in nongrafted vessels was not significantly increased by the presence of one, two, or three risk factors. Over all, there was progression in 56% of segments proximal to grafts, in 8% distal to grafts, and in 14% of nongrafted vessels. Longer term studies will be required to establish any adverse influence of these risk factors on saphenous vein bypass grafts and native circulation.