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Biomedical subjects

R S Crampton

Publications and source records attributed to R S Crampton.

At least 37 records · Page 2Linked to original sources
PubMed1982

Analysis of pacemaker malfunction and complications of temporary pacing in the coronary care unit.

The medical records of 100 patients who received 113 temporary transvenous pacemakers were reviewed to determine the incidence of complications and malfunction. Malfunction, defined as failure to capture or sense, or both, occurred in 42 (37 percent) of 113 temporary pacemakers. The initial malfunction occurred within 24 hours in 21 (50 percent) and within 48 hours in 36 (86 percent) of the 42 pacemakers. Although the incidence of malfunction was not significantly different for brachial and femoral venous pacing catheters, 7 (37 percent) of 19 brachial venous pacemakers required repositioning or replacement compared with 8 (9 percent) of 91 femoral venous catheters (p = 0.005). Thirty-seven complications occurred in 23 (20 percent) of 113 episodes of pacing; ventricular tachycardia during catheter insertion, fever and phlebitis were the most common complications. No complication resulted in death. The incidence of complications and perforation was greater for brachial than for femoral venous pacemakers (p less than 0.05). Sepsis, local infection and pulmonary embolus occurred only with femoral venous pacemakers. Sepsis, phlebitis and pulmonary embolus were more common with temporary pacemakers in place for 7 hours or longer (p = 0.04). Recognition to the problems peculiar to each pacing catheter site and shortening the duration of pacing should help minimize problems with temporary pacing.

Adult↗
PubMed1982

Precordial ST-segment depression during acute inferior myocardial infarction: clinical, scintigraphic and angiographic correlations.

The cause and associated pathophysiology of precordial ST-segment depression (ST decreases) during acute inferior myocardial infarction (IMI) are controversial. To investigate this problem, electrocardiographic findings in 48 consecutive patients with acute IMI were prospectively compared with results of coronary angiography, submaximal exercise thallium-201 (201TI) scintigraphy and multigated blood pool imaging, all obtained 2 weeks after IMI, and with clinical follow-up at 3 months. Patients were classified according to the admission ECG obtained 3.3 +/- 3.1 hours after the onset of chest pain. Twenty-one patients (group A) had no or less than 1.0 mm ST decreases, and 27 (group B) had greater than or equal to 1.0 mm ST decreases in two or more precordial (V1-6) leads. Patients in group B had more prolonged chest pain after admission to the coronary care unit than those in group A (2.8 +/- 3.0 vs 1.2 +/- 1.1 hours, p less than 0.03), greater summed ST-segment elevation in leads II, III, aVF (6.7 +/- 4.7 vs 3.3 +/- 4.5 mm, p less than 0.02), higher plasma peak creatine kinase levels (1133 +/- 781 vs 653 +/- 482 IU/l, p less than 0.01), a higher prevalence of "true posterior" infarction by ECG criteria (26% vs 5%, p less than 0.05), a lower radionuclide ejection fraction (46 +/- 9% vs 54 +/- 6%, p less than 0.001), more extensive infarct-related asynergy (p less than 0.001) and 201TI perfusion abnormalities (p less than 0.01), more complications during hospitalization (p less than 0.03), and more cardiac events at 3 months (p less than 0.02). There were no significant differences between group A and group B in the extent of underlying coronary disease, prevalence of left anterior descending coronary artery disease, exercise-induced ST decreases or angina, and 201TI defects or wall motion abnormalities in anterior or septal segments. Thus, patients with acute IMI who have associated precordial ST decreases have greater global and regional left ventricular dysfunction due to more extensive inferior or inferoposterior wall infarction, rather than concomitant anteroseptal ischemic injury.

Angina Pectoris↗
PubMed1981

Prolonged QT interval at onset of acute myocardial infarction in predicting early phase ventricular tachycardia.

The prospectively assessed time course of changes in ventricular repolarization during acute myocardial infarction (AMI) is reported in 32 patients admitted 2.0 +/- 1.8 (SD) hours after AMI onset. The initial corrected QT interval (QTc) upon hospitalization was longer (0.52 +/- 0.07 seconds) in the 14 patients developing ventricular tachycardia (VT) within the first 48 hours as compared to QTc (0.47 +/- 0.03 seconds) in the eight patients with frequent ventricular premature beats (VPBs) and to QTc (0.46 +/- 0.03 seconds) in the 10 patients with infrequent VPBs (p less than 0.001; analysis of variance). By the fifth day after AMI onset, the QTc shortened significantly only in the VT group, suggesting a greater initial abnormality of repolarization in these patients. All 32 patients had coronary angiography, radionuclide ventriculography, and myocardial perfusion scintigraphy before hospital discharge. Significant discriminating factors related to early phase VT in AMI included initially longer QT and QTc intervals, faster heart rate, higher peak serum levels of creatine kinase, acute anterior infarction, angiographically documented proximal stenosis of the left anterior descending coronary artery, and scintigraphic evidence of hypoperfusion of the interventricular septum. Prior infarction, angina pectoris, hypertension, multivessel coronary artery disease, and depressed left ventricular ejection fraction did not provide discrimination among the three different ventricular arrhythmia AMI groups. We conclude that (1) the QT interval is frequently prolonged early in AMI, (2) the initial transiently prolonged ventricular repolarization facilitates and predicts complex ventricular tachyarrhythmias within the first 48 hours of AMI, (3) jeopardized blood supply to the interventricular septum frequently coexists, and (4) therapeutic enhancement of rapid recovery of the ventricular repolarization process merits investigation for prevention of VT in AMI.

Acute Disease↗
PubMed1981

Predicting the extent and location of coronary artery disease during the early postinfarction period by quantitative thallium-201 scintigraphy.

The ability of quantitative thallium-201 scintigraphy to predict the extent and location of coronary artery disease before hospital discharge after acute myocardial infarction was evaluated in 52 patients. All patients underwent coronary angiography and serial thallium-201 imaging either at rest (10 patients) or after submaximal exercise stress (42 patients; target heart rate 120 beats/min). Two or three vessel disease was designated if abnormal thallium-201 uptake or washout patterns, or both, were seen in two or three vascular segments, respectively. Of 156 vessels analyzed in the 52 patients, 91 stenoses of 70 percent or greater were found by angiography. Seventy-four (81 percent) of these were predicted by scintigraphy. The specificity of scintigraphy for identifying vessel stenoses was 92 percent. Sensitivity for detecting and localizing stenoses supplying an infarct zone was 96 percent compared with 62 percent for stenoses supplying myocardium remote from the acute infarct. Perfusion abnormalities were more frequently seen in the distribution of vessels with severe (90 percent or greater) stenoses than in those with moderate (70 to 90 percent) stenoses (87 versus 53 percent, p less than 0.01). Scintigraphy detected a greater proportion of left anterior descending and right coronary arterial stenoses than circumflex stenoses (91 and 87 versus 63 percent, respectively, p less than 0.006). In the 42 patients who underwent submaximal exercise testing, multivariate analysis of 23 clinical and laboratory variables identified multiple thallium-201 defects as the best predictor of multivessel disease. The predictive accuracy of exercise-induced S-T segment depression was only 45 percent compared with 88 percent (p less than 0.05) for thallium-201 scintigraphy. Thus, 2 weeks after myocardial infarction, exercise thallium-201 scintigraphy is useful for predicting the extent and location of coronary artery disease, particularly stenoses in the left anterior descending and right coronary arteries. Moreover, thallium-201 imaging at rest is reliable in assessing the extent of coronary disease in hospitalized patients who cannot undergo exercise testing because of unstable angina, uncompensated heart failure, poorly controlled arrhythmias or physical limitations.

Adult↗
PubMed1980

Diagnosis, not energy or weight, determines ventricular defibrillation.

In a study demonstrating 95% success in achieving defibrillation in 94 resuscitative events in adult patients, the authors find that weight did not determine that success and that the results were obtained at significantly low rates of energy output. Diagnosis was the key, they conclude, and they view the expensive high-energy defibrillators marketed today as unnecessary, potentially lethal, and economically wasteful.

Body Weight↗
PubMed1980

Prognostic significance of resting anterior thallium-201 defects in patients with inferior myocardial infarction.

To determine whether Tl-201 scintigraphy performed at rest during the late hospital phase of inferior myocardial infarction can predict subsequent coronary events, 25 patients with historical, enzymatic, and electrocardiographic criteria of transmural inferior infarction underwent serial imaging with computer quantification 7-35 days after admission. All 25 patients had inferior defects, and 13 (52%) also had anterior defects implying stenosis of the left anterior descending coronary artery. The patients were divided into those with inferior and anterior perfusion defects (Group 1) and those with inferior defects alone (Group 2). In Group 1, three patients had persistent defects in the anterior wall and ten had initial defects with redistribution. New or recurrent coronary events--which included new onset or progression of angina pectoris, sudden death, reinfarction, and congestive heart failure--were recorded over an average 7.2 months of followup (range 3-9 mo) for all patients. Ten of 13 (77%) patients in Group 1 had 17 coronary events and four of 12 (33%) patients in Group 2 had six coronary events (p < 0.02). Nine patients in Group 1 and three in Group 2 developed angina (p < 0.03). The apparently increased prevalence in Group 1 of sudden death (8% against 0%), reinfarction (8% against 0%), and congestive heart failure (46% against 25%) was not statistically significant. Thus resting Tl-201 scintigraphy with computer quantification is a highly sensitive method to detect inferior myocardial infarction even in the late hospital phase. Moreover, it appears to identify those patients with inferior infarction at high risk for subsequent coronary events, presumably due to stenosis of the left anterior descending coronary artery.

Aged↗
PubMed1979

Energy levels and patient weight in ventricular defibrillation.

In a prospective survey employing conventional devices that stored 400 joules or less, direct-current shocks that delivered 194 +/- 11 joules (1.8 joules/kg) to the chest wall terminated 45 of 46 episodes of ventricular fibrillation in 11 of 12 patients weighing 91 to 225 kg. Patients with coronary disease defibrillated more easily than patients without coronary disease. Weight did not determine outcome. The 98% defibrillation efficiency occurred at only half the energy predicted for 50% efficiency from retrospective data. Human defibrillation not only occurred at one third the untested level recommended by proponents of high-energy defibrillation, but also at one fourth the energy, defibrillating 69% of comparably heavy animals. Thus, the costly defibrillators delivering 400 to 800 joules now sold by 11 of 14 American manufacturers are superfluous, untested, potentially lethal devices with which to attempt ventricular defibrillation.

Adolescent↗
PubMed1979

Determinants of ventricular defibrillation in adults.

Conventional defibrillators which stored no more than 400 J and used damped sine wave pulses defibrillated 240 of 253 (95%) episodes of ventricular fibrillation (VF) in 94 prospectively assessed resuscitations in 88 adults. Shocks of 80--240 J (under 3 J/kg) delivered to the chest wall defibrillated more often than higher energy levels. Defibrillation rate did not correlate with weight. Defibrillation was determined by the diagnosis and setting in which VF occurred. Patients with acute myocardial infarction (AMI) and primary VF or with coronary disease and no AMI defibrillated more easily than patients with AMI and secondary VF or with no coronary disease. VF in a terminal patient (agonal VF) defibrillated less often than VF in other clinical situations. Age, weight, delivered energy, duration of pulse wave, and duration of VF had little, if any, influence on rate of defibrillation. These data fail to support the use of more expensive, high-output defibrillators sold by 11 or 14 American manufactures.

Adult↗
PubMed1977

Factors influencing survival of patients with permanent cardiac pacemakers.

With the advent of permanent cardiac pacing, technology has produced power sources that will last two, four, and even 20 years. The cost of these devices is proportional to their complexity and expected life. Therefore, the selection of an appropriate pulse generator should be based on the patient's prognosis. An actuarial analysis of 319 consecutive patients receiving permanent cardiac pacemakers was performed in order to determine whether prepacing factors influenced prognosis. The survival probability at 5 years was not influenced by sex, race, type of conduction defect, or antecedent disease. Survival rate decreased only slightly for each decade of life, but even in the ninth decade there was an acceptable prognosis.

Age Factors↗
PubMed1975

Idiopathic ventricular tachycardia. An intracardiac electrical, hemodynamic and angiographic assessment of six patients.

Six patients with idiopathic paroxysmal ventricular tachycardia were investigated by external electrocardiography, intracardiac electrography and pacing, exercise testing, cardiac catheterization and coronary angiography. All had normal hemodynamics and coronary arteries. His bundle electrography proved ventricular origin in five; one had no paroxysmal ventricular tachycardia during His bundle electrography. Treatment with diphenylhydantoin, 4.2 to 8.0 mg/kg/day, and propranolol, 0.8 to 2.7 mg/kg/day, appeared effective, well tolerated therapy in three, and procainamide and propranolol in one requiring medical treatment. Abstinence from tobacco and coffee abolished paroxysmal ventricular tachycardia in one of two who required no medication. The other has no recurrence of paroxysmal ventricular tachycardia since study.

Adult↗
PubMed1975

Reduction of prehospital, ambulance and community coronary death rates by the community-wide emergency cardiac care system.

Initiation of quick prehospital cardiopulmonary resuscitation and emergency cardiac care completed the total system needed to provide emergency and convalescent coronary care for a community. Subsequently, annual community rates for coronary death during ambulance transport fell by 62 per cent and for prehospital coronary death by 26 per cent in people under 70 years of age. In cardiac arrest due to acute myocardial infarction, prompt successful prehospital correction of ventricular fibrillation and asystole yielded long-term survival in two thirds of cases. This 66 per cent success rate of prehospital cardiopulmonary resuscitation and emergency cardiac care is identical to contemporary international experience. Precordial thump-version with the fist and precordial fist pacing appeared logical additions to prehospital cardiopulmonary resuscitation and emergency cardiac care technics. Community lives saved yearly were 15.2/100,000 people aged 30 to 69 years and 6.4/100,000 total population. Simultaneously, annual community rates for coronary death as a cause of death and coronary death per 1,000 people fell significantly by 15 and 17 per cent, respectively. Unquantifiable influences included prehospital relief of ischemic chest pain; prehospital correction of acute dysautonomia; prehospital abolition of otherwise prefatal dysrhythmias; similar treatment for acute myocardial infarction in the emergency department, in the inhospital mobile coronary care unit and in the progressive intermediate coronary convalescent unit; and general community education through the media of newspapers, radio and television. The present frequency of coronary death during ambulance transport, 9 to 22 per cent of prehospital coronary deaths in this and other surveys, suggests that the prehospital cardiopulmonary resuscitation and emergency cardiac care component needs improvement in many communities. By reducing prehospital and ambulance coronary death rates, prehospital cardiopulmonary resuscitation and emergency cardiac care for acute myocardial infarction constitutes an essential component of the total system approach to emergency coronary care. Since prehospital cardiopulmonary resuscitation and emergency cardiac care have cheaply and effectively expedited and abbreviated hospitalization for acute myocardial infarction, and lowered community death rates from coronary artery disease, its adoption throughout the United States and the western world seems justified.

Ambulances↗
PubMed1975

Cardiac rhythm in men during cystoscopy.

Cardiac rhythm was monitored prospectively in 69 men during 191 cystoscopies. Ectopic beats from ventricular and supraventricular foci occurred in a significantly greater proportion of procedures in men with (76 per cent) compared to men without (16 per cent) heart disease. Other arrhythmias occurred to a lesser extent but there was no significant difference between men with and without heart disease. Plasma lidocaine was detected in significant amounts following intraurethral injection used for local anesthesia. Comparison of the types of arrhythmias that occurred during cytoscopy and the type of anesthetic used showed that significantly fewer ventricular ectopic beats occurred with general (8 per cent) or epidural anesthesia (13.8 per cent) as opposed to local lidocaine anesthesia (48.7 percent). Among the 3 anesthetic groups there was no difference with respect to frequency of supraventricular ectopic beats. No permanent cardiovascular complications occurred although several potentially serious dysrhythmias were seen.

Adult↗