Duration of positive throat cultures for group A streptococci after initiation of antibiotic therapy.

OBJECTIVE: To determine if it is appropriate to recommend that patients with group A beta-hemolytic streptococcal pharyngitis, who are clinically well by the morning after starting antibiotic treatment, can return to school or day care, or if they should wait until they have completed 24 hours of antibiotics as recommended by the American Academy of Pediatrics Committee on Infectious Diseases. METHODS: We examined the duration of positivity of the throat culture after antibiotics were begun as a means of assessing the potential risk of transmission to close school contacts. Forty-seven children (4 to 17 years of age) with pharyngitis and a positive throat culture for group A streptococci in an outpatient, staff model health maintenance organization clinic were enrolled and were randomly selected to receive therapy with either oral penicillin V, intramuscular benzathine penicillin G, or oral erythromycin estolate. Additional throat cultures were obtained and clinical findings were recorded for each child during three home visits in the 24 hours after their initial clinic visit. Acute and convalescent sera were obtained for determination of anti-streptolysin O and anti-DNase B titers. RESULTS: Seventeen (36.2%) of the 47 patients had a positive culture the morning after initiating antibiotic therapy. However, thirty-nine (83%) of the patients became "culture negative" within the first 24 hours. Neither the time interval to the first negative culture nor the presence or absence of group A streptococcal organisms on any single convalescent culture could be predicted by clinical findings. Six of the eight children who failed to convert to a "negative" throat culture within 24 hours of initiating therapy were receiving erythromycin. We could detect no difference in either time to conversion to a negative culture or the presence of a positive culture 24 hours after starting antibiotics between those who demonstrated a significant antibody increase and those who did not. CONCLUSION: The data from this study strongly suggest that children with group A beta-hemolytic streptococcal pharyngitis should complete a full 24 hours of antibiotics before returning to school or daycare.

Differential diagnosis of patients with abnormal serum creatine kinase isoenzymes.

For the diagnosis of myocardial injury, particularly AMI, CK-MB has become the gold standard. Changing CK-MB activities in serially collected blood from patients with suggestive signs and symptoms of AMI is almost pathognomonic for infarction. Nevertheless, an increased CK-MB cannot be equated with AMI owing to the many other types of inflammatory, traumatic, and miscellaneous forms of injury to the heart and the trace activities of CK-MB in skeletal muscle. Other enzyme tests for AMI are less efficient. In order of decreasing efficiency, the tests are CK-MB, CK, LD1 greater than LD2 or LD1/LD2 greater than 0.76, AST and LD; the latter two tests are not cost effective and add little or nothing when results for CK-MB, CK, and LD isoenzymes are available. The value of the isoforms of CK-MM and CK-MB remains to be established. Early evidence suggests that they could be helpful in the diagnosis of AMI; however, owing to the greater technical difficulties in performing these tests, their use is necessarily more restricted. Enzyme testing on admission and then every 12 hours for 2 days is sufficient and effective in making the initial diagnosis. In patients presenting early after an attack, CK and CK-MB are often normal. Decisions on AMI cannot be made on blood tests collected in the emergency department. Clot-lysing agents like streptokinase, urokinase, and tPA have changed the therapy of AMI dramatically. Enzyme tests clearly separate patients with and without successful therapeutic or spontaneous reperfusion. With successful reperfusion, the uniform finding has been a "washout" phenomenon with significantly earlier peaking times for CK and CK-MB. The isoforms of CK and myoglobin give the earliest peaks after successful reperfusion. With faster turnaround times for these tests, they may become important tools in patient management.

Mitral valve prolapse: cardiac arrest with long-term survival.

Cardiac arrest has been reported in patients with mitral valve prolapse; however, clinical characteristics and survival information are limited since most of the cases reported include autopsy data. Nine patients (2 male, 7 female) with mitral valve prolapse were identified who had cardiac arrest; ventricular fibrillation was documented in 8 patients; resuscitation was unsuccessful in 2. Eight had a history of palpitations (months to 15 years duration) and ventricular arrhythmias, 3 had a history (5-15 years) of recurrent syncope, and 1 was totally asymptomatic. Cardiac catheterization-angiographic studies in 8 patients demonstrated normal coronary artery anatomy and mitral valve prolapse. All 9 patients had auscultatory and echocardiographic evidence of mitral valve prolapse. Seven survivors (6 still alive) were followed from 3 to 14 years after cardiac arrest. A subset of patients with mitral valve prolapse and cardiac arrest is described in whom past medical history is compatible with cardiac arrhythmias or syncope, and whose long-term prognosis appears better than patients with other causes of cardiac arrest.

Arrhythmic syncope: what to do when ambulatory monitoring is non-diagnostic.

The two new methods for defining arrhythmic syncope described in this report represent important additions to the traditional syncope workup. Both techniques uncovered a substantial number of arrhythmic causes of syncope which had not been found by standard techniques. A major strength of each method is that symptoms can be directly related to the arrhythmia. The 68% incidence of diagnostic EPS abnormalities which we found was identical to the study of DiMarco but higher than reported by others (which have ranged from 12 to 48%) (18, 20, 21). More critical patient selection and more comprehensive study techniques most likely account for these differences. It is our opinion that a significant number of patients whose diagnosis was "syncope of undetermined etiology" in previous studies did indeed have an arrhythmic basis for their symptoms which was not identified. At this point the issue of "cost effectiveness" inevitably arises. Do all patients with syncope in whom a cause is not initially apparent (i.e., up to 50% of such patients) require either TTEM or EPS? The answer is obviously no, not for this whole population. However, the evident power of TTEM and EPS requires that the question should be raised. Furthermore, the results of the invasive EPS study strongly suggest that mortality and morbidity can be reduced. Table 11 shows the relative costs for all of the diagnostic tests for arrhythmic syncope. From this it can be seen that TTEM is quite inexpensive and therefore very cost-effective. It is an ideal adjunct to 24 hour ambulatory monitoring in selected patients. Although invasive EPS studies are costly, it is not difficult to incur equal costs by use of several days of prolonged monitoring, especially if done in the hospital. Thus, in identified patients with abnormal but "not diagnostic" ambulatory monitoring studies, patients with abrupt syncope, patients with frequent symptoms or patients with known underlying heart disease, further evaluation with TTEM or EPS should be strongly considered.

Methacholine provocation of Prinzmetal's variant angina pectoris: a revised perspective.

We report 13 patient with unequivocal Prinzmetal's variant angina pectoris as the entire experience with this syndrome during a 7-year period in a single institution. The clinical diagnosis of this relatively uncommon disorder is emphasized. Five patients were given 10 mg of methacholine subcutaneously. Three demonstrated subsequent delayed appearance of chest pain, ECG change, and coronary vasospasm following early appearance of muscarinic effects. Two Prinzmetal patients had no provocation of variant angina following methacholine, though they did experience significantly less blood pressure fall in response to muscarinic provocation. Another 23 subjects with incompletely explained chest pain given methacholine had neither ECG change nor spasm. Methacholine provocation of variant angina need not necessarily implicated a parasympathomimetic mechanism for otherwise spontaneous episodes. Rather, provocation would appear to occur via the customary reflex adrenergic response to drug-induced hypotension. Methacholine is probably safe though unreliable as an agent to be used for spasm provocation.

Acute massive (pericardial effusive) pulmonary thromboembolism--pulmonary embolectomy revisited.

The most recent patient in a 13-year experience with 14 patients suffering massive pulmonary thromboembolism requiring pulmonary thromboembolectomy is the focus of this report. This 40-year-old woman not only survived life-threatening acute hypoxemia and right heart failure, but was also found to have developed a unique transudative 700 cc pericardial effusion. Pulmonary artery pressure was 90/30 (mean 50 mmHg), accompanied by 17 mm right ventricular alternans. Systemic alternans and tamponade physiology were absent. This unusual natural model for acute right heart failure illustrates a novel mechanism for pericardial effusion physiology.

Serum enzymes and isoenzymes in the diagnosis and differential diagnosis of myocardial ischemia and necrosis.

Diagnosis of injury to the myocardium is facilitated by information on the activities of creatine kinase (EC 2.7.3.2) MB isoenzyme (CK-MB) and lactate dehydrogenase (EC 1.1.1.27) isoenzyme 1 in serum, thee isoenzymes being present in higher activities in the myocardium than in other tissues or in normal serum. The temporal relationships of these isoenzymes, total creatine kinase, total lactate dehydrogenase, and aspartate aminotransferase (EC 2.6.1.1) are highly sensitive and specific for acute injury to the heart, particularly acute myocardial infarction. Chronic heart diseases, electric cardioversion for heart rhythm disturbances, coronary catheterization, and exercise usually do not produce increases of CK-MB, although abnormal aspartate aminotransferase, creatine kinase, lactate dehydrogenase, and lactate dehydrogenase isoenzyme 1 activities are seen in some individuals. Many other causes of increased activities of these enzymes and isoenzymes in serum are unrelated to injury to the heart. Because CK-MB is present in the skeletal muscle in low activities, substantial injury to skeletal muscle can increase CK-MB activities in the blood to abnormal values. Pulmonary embolism can mimic myocardial infarction in its clinical presentation. In patients with an accurately known time of onset of symptoms and serial enzyme analysis every 12 h during the first 48 h, acute myocardial infarction can be distinguished from pulmonary embolism by determinations of creatine kinase, CK-MB, aspartate aminotransferase, and lactate dehydrogenase isoenzyme 1 in serum.

Samuel A Levine's first world war encounters with Mackenzie and Lewis.

Samuel Albert Levine was a key figure in modern cardiology in the United States. During the first world war he was one of a select group of United States medical officers assigned to the British Military Heart Hospital where he encountered the "British medical giants"--Clifford Allbutt, William Osler, James Mackenzie, and Thomas Lewis. Levine's diary, written when he was a young medical officer during the first world war, presents crisp character sketches of James Mackenzie and Thomas Lewis. The autobiographical vignettes he wrote later in life were more gracious and polished retrospectives. The Levine perspectives, separated by a half century, contribute to our understanding of the developing fabric of Anglo-American cardiology.

The role of paramedics in resuscitation of patients with prehospital cardiac arrest from coronary artery disease.

Columbus, Ohio added prehospital coronary care to its Emergency Medical Services System (EMS) in 1969. The EMS System, which is citizen activated and tax supported (+5 per citizen per year), currently sees 32,000 patients a year in a city with a population of 650,000. Ninety-six per cent of the population is aware of the system. Over two thirds of patients with ischemic sudden death or myocardial infarction are seen by advanced life support paramedic (EMT-P) units. The EMT-Ps operate by protocol without telemetry and carry all standard resuscitative drugs and devices. Serial evaluations have shown that within the limits of the protocol, the EMT-Ps perform as effectively as physicians in diagnosis and care of acute cardiovascular emergencies, including endotracheal intubation. One third of ischemic cardiac arrest patients in whom resuscitation is possible (60% of such patients seen) are discharged from the hospital alive (14.2/100,000 lives saved per year). Lives are also saved by treatment of other life-threatening prehospital complications. In Columbus, the estimated annual mortality from ischemic heart disease is only 19%. The EMS System contributes significantly to this low figure.

Occult constrictive pericardial disease. Diagnosis by rapid volume expansion and correction by pericardiectomy.

Significant pericardial disease can exist without overt manifestations. Occult constrictive pericardial disease (OCPD) is identified by normal baseline hemodynamics and normal left ventricular systolic function with a characteristic response to rapid volume infusion. Following the intravenous administration of 1000 ml of normal saline over six to eight minutes, striking elevations of filling pressures are seen; however, diagnosis depends specifically upon a) the development of typical pressure pulse morphology of constriction, b) loss or reversal or respiratory variation of right atrial pressure, and c) precise diastolic equilibration of intracardiac pressures. Nineteen patients with OCPD have been identified in a five year period. Unexplained fatigue, dyspnea and chest pain was the uniform pattern of presentation. Eleven have undergone pericardiectomy resulting in a dramatic symptomatic improvement in all. Each demonstrated gross and/or microscopic evidence of pericardial disease. Recatheterization with volume infusion in five patients following pericardiectomy has revealed return to normal or near normal hemodynamics. This study describes the method for diagnosis of OCPD and recommends pericardiectomy for the management of disabling symptoms.

The way we teach: anatomy of the coronary artery system.

A simple model to enhance understanding of the three-dimensional anatomy of the human epicardial coronary artery circulation is discussed and potential instructive applications reviewed. The chambers of the heart are visualized as being related to one another as in a pair of opposed hands, which can be rotated to demonstrate the various structures as viewed in different angles of obliquity.

Effectiveness of advanced paramedics in a mobile coronary care system.

The mobilized coronary care system in Columbus, Ohio, began with operation of a single vehicle with a physician in attendance. Currently, advanced emergency medical technician-paramedics work without direct physician supervision. When both experiences are compared, the results indicate that advanced emergency medical technician-paramedics working independently perform as well as physician counterparts.

The electrophysiologic effects of upright posture.

In order to determine the effects of upright posture on the electrophysiologic properties of the human heart, 12 patients underwent electrophysiologic studies in the supine and upright positions. Compared to supine, the upright position significantly reduced basic cycle length from 818 +/- 111 to 680 +/- 141 msec, sinoatrial conduction time from 186 +/- 94 to 135 +/- 56 msec, corrected sinoatrial recovery time from 206 +/- 104 to 108 +/- 55 msec, interatrial conduction time from 76 +/- 17 to 70 +/- 16 msec, and the AV nodal conduction time (AH interval) from 88 +/- 19 to 78 +/- 14 msec (all p less than 0.05). Right intra-atrial and His-Purkinje (HV interval) conduction times were not altered. When the subjects assumed the upright position, the effective refractory periods of the right atrium, atrioventricular node, and right ventricle decreased significantly at basic and paced cycle lengths. For the group as a whole, the upright posture did not significantly augment repetitive responses to atrial and ventricular extrastimuli.

Treatment of prehospital refractory ventricular fibrillation with bretylium tosylate.

Among 218 patients treated for prehospital arrest during an eight-month baseline period prior to addition of bretylium tosylate to the paramedic protocol in Columbus, 16 (7.3%) were seen with refractory ventricular fibrillation (RVF). These patients failed to respond to multiple countershocks, lidocaine, bicarbonate and epinephrine, and either were transported in arrest during cardiopulmonary resuscitation (CPR)(14) or were pronounced dead at the scene (2). A single patient was eventually resuscitated in and discharged from the hospital. During the subsequent 16 1/2-month experience with bretylium used only for prehospital RVF, 421 patients with prehospital arrest were seen, 35 of whom (8.3%) had RVF. All but five patients were defibrillated successfully, and 14 (40%) were converted to a rhythm sufficient to obviate CPR during transportation. Eleven patients (31%) survived to be admitted to the hospital, and eight of 35 (23% vs 1/16 or 6.2% above, P less than .05) were discharged and remained well three to 17 months later. Bretylium tosylate may provide life-saving therapy for refractory prehospital ventricular fibrillation so that survival from an almost uniformly fatal condition is improved. While patients with persistent arrest generally should be transported to the hospital, such patients should not be subjected to the difficulties of CPR in transit unless they are first given bretylium if RVF is present.