Valavanur A. Subramanian

Dysrhythmias caused by histamine release in guinea pig and human hearts

SummaryHistamine is released into the systemic circulation during anaphylaxis, by drugs and by surgical procedures. Studies in animal models have conclusively demonstrated that released cardiac histamine is a major mediator of arrhythmias that occur during anaphylaxis and following the administration of histamine-releasing drugs. Several lines of evidence suggest a similar arrhythmogenic role for cardiac histamine in humans: (1) The human heart is rich in histamine; (2) cardiac histamine can be readily released from human heartin vitro by therapeutic concentrations of drugs; (3) histamine has potent arrhythmogenic effects on the human heartin vitro.Arrhythmogenic effects of histamine include enhancement of normal automaticity, induction of abnormal automaticity, induction of triggered tachyarrhythmias, depression of atrioventricular conduction, and increase in the vulnerability of the ventricles to fibrillation. A combination of H1 and H2 antihistamines is needed to block the arrhythmogenic effects of histamine. Certain arrhythmogenic effects of histamine (e.g. induction of slow responses and delayed afterdepolarizations) can also be blocked by drugs which inhibit the influx of cations through slow channels. In contrast, the commonly-used drug digitalis potentiates the arrhythmogenic effects of histamine.We propose that histamine release produced by drugs and surgical procedures may be an overlooked factor in fatal cardiac arrhythmias. Experimental studies suggest that selective pharmacological methods can be developed to block the arrhythmogenic effects of histamine.ZusammenfassungWährend der Anaphylaxie durch Arzneimittel und chirurgische Eingriffe wird Histamin in den systemischen Kreislauf freigesetzt. Durch Tierstudien konnte eindeutig gezeigt werden, daß freigesetztes Histamin aus dem Herzen ein Hauptmediator für Arrhythmien ist, die während Anaphylaxie nach Gabe von histaminfreisetzenden Arzneimitteln auftreten. Verschiedene Gründe weisen auf eine ähnliche arrhythmogene Rolle für kardiales Histamin beim Menschen hin:(1) Das menschliche Herz ist reich an Histamin; (2) kardiales Histamin kann vom menschlichen Herzenin vitro durch therapeutische Arzneimittelkonzetrationen schnell freigesetzt werden; (3) Histamin hat einen starken arrhythmogenen Effekt auf das menschliche Herzin vitro.Arrhythmogene Effekte des Histamins schließen die Erhöhung der normalen Herztätigkeit, die Induktion einer abnormalen Herztätigkeit, die Induktion von verstärkten Tachyarrhythmien, die Verminderung arterioventrikulärer Reize und eine Erhöhung in der Empfindlichkeit der Ventrikel für Herzflimmern ein. Eine Kombination von H1-and H2-Antihistaminika ist notwendig, um die errhythmogenen Effekte des Histamins zu blockieren. Bestimmte arrhythmogene Effekte des Histamins (z.B. die Induktion von verlangsamten Reaktionen und verzögerten Nachdepolarisationen) können auch durch Arzneimittel blockiert werden, die den Einfluß von Kationen durch die langsamen Kanäle hemmen. Im Gegensatz dazu verstärkt das allgemein gebräuchliche Mittel Digitalis die arrhythmogenen Effekte des Histamins.Wir vermuten, daß Histaminfreisetzung durch Arzneimittel und chirurgische Eingriffe ein häufig übersehener Faktor bei tödlichen Herzarrhythmien sein könnte. Experimentelle Studien legen nahe, daß selektive pharmakologische Methoden entwickelt werden können, um die arrhythmogenen Effekte des Histamins zu verhindern.

Management of thoracic empyema

Over a ten year period, 102 patients with thoracic empyemata were treated at Boston City Hospital. Only three patients died from the pleural infection while twenty-six succumbed to the associated diseases. Priniciples of management include: (1) thoracentesis; (2) antibiotics; (3) closed-tube thoracostomy; (4) sinogram; (5) open drainage; (6) empyemectomy and decortication in selected patients; and (7) bronchoscopy and barium swallow when the etiology is uncertain.

Effect of Preoperative Antiplatelet Drugs on Vascular Prostacyclin Synthesis

Patients undergoing aortocoronary bypass using autogenous saphenous veins were randomly divided into three comparable groups. Group 1 (n = 10) acted as a control, Group 2 (n = 14) received 80 mg of aspirin at midnight before the operation, and Group 3 (n = 12) received 80 mg of aspirin and 75 mg of dipyridamole at midnight and an additional 75-mg dose of dipyridamole at 6 AM. The purpose was to determine which regimen would maximally inhibit platelet function without depressing vascular prostacyclin synthesis. Serum thromboxane A2, saphenous vein wall and aortic wall prostacyclin, platelet aggregation, and bleeding time were measured in all patients. None was restarted on a regimen of aspirin or dipyridamole postoperatively. Aspirin alone and in combination with dipyridamole significantly inhibited thromboxane A2 and platelet aggregation in all treated patients but spared venous prostacyclin synthesis. Aortic prostacyclin synthesis was partially inhibited in both treated groups. Chest tube drainage was comparable in all three groups. These results indicate that the combination of aspirin and dipyridamole offers no measurable advantage over aspirin alone in the perioperative period.

Perioperative Myocardial Infarction Associated with Coronary Artery Bypass Graft Surgery: Improved Sensitivity in the Diagnosis Within 6 Hours after Operation with 99mTc-Glucoheptonate Myocardial Imaging and Myocardial-Specific Isoenzymes

The present study was performed to evaluate scintigraphic imaging with technetium 99m-labeled glucoheptonate and serum enzyme levels of creatine phosphokinase isoenzyme (MB-CPK) in the early diagnosis of perioperative acute myocardial infarction associated with saphenous vein bypass graft operations. Myocardial imaging was done in 27 patients (50% of whom were considered high-risk) before operation and again 5 hours after operation. Four of these patients (15%) had both electrocardiographic and serum MB-CPK evidence of acute myocardial infarction, and all 4 had developed positive postoperative scintigrams. Four other patients had only elevated serum MB-CPK, and scintigrams became positive after operation in 3 of them. In addition, serum MB-CPK 6 hours after operation was 83 +/- 21 mIU/ml (mean +/- standard error of the mean) in patients with positive postoperative scans compared with 24 +/- 5 mIU/ml in those patients with negative postoperative scintigrams (p less than 0.001). Myocardial imaging with 99mTc-glucoheptonate in the perioperative period is rapid, safe, and atraumatic. Furthermore, our results suggest that it is a sensitive method for the early diagnosis of perioperative acute myocardial infarction, and, when imaging is combined with serum MB-CPK isoenzyme analysis, the reliability of the diagnosis of acute myocardial infarction is enhanced even further. Only 1 of the patients who showed perioperative myocardial damage had acute hemodynamic compromise or obvious impairment of recovery in the immediate postoperative period, and the 30-day mortality of the total group was 4% (1 of 27).

Response to intra-aortic balloon pumping☆

Abstract Mechanical circulatory assistance utilizing the intra-aortic balloon pump was employed sixty-five times in a series of sixty-three patients with the following clinical conditions: (1) cardiogenic shock after myocardial infarction, with subsequent medical management in fourteen patients; (2) cardiogenic shock after myocardial infarction with subsequent surgical management in four patients; (3) preinfarction angina syndrome in six patients; (4) septic shock in five patients; (5) postcardiotomy cardiogenic shock with dependence on cardiopulmonary bypass in twenty-six patients; (6) postcardiotomy cardiogenic shock during the recovery period in seven patients; (7) miscellaneous indications in three patients. Duration of assistance with intra-aortic balloon counterpulsation varied between 2 and 172 hours. Hemodynamic monitoring of arterial, central venous, pulmonary arterial, and left ventricular filling pressures was performed. Frequent measurements of cardiac output by a thermodilution technic with determination of cardiac index and left ventricular stroke work index in twenty patients provided an assessment of left ventricular function with and without intra-aortic balloon counterpulsation. Intra-aortic balloon counterpulsation produced effective assistance in fifty-four of sixty-five cases (83 per cent). In fifty-four patients in shock with low cardiac output, effective mechanical circulatory assistance with intra-aortic balloon counterpulsation was established in forty-six (85 per cent) as evidenced by reversal of the shock state. Cardiac index and left ventricular stroke work index were improved by intra-aortic balloon counterpulsation in most instances, particularly if left ventricular filling pressures were 15 to 20 mm Hg. There were thirty-two survivors (51 per cent).

Integrated minimally invasive approaches for the treatment of atherosclerotic vascular diseases: Hybrid procedures

Patients may develop simultaneous symptoms of atherosclerotic vascular disease from different arterial beds. A concurrent minimally invasive approach to the management of these clinical situations may be an advantage over conventional surgical procedures. This study describes two separate case series of patients undergoing coronary/peripheral (n = 38) and peripheral/peripheral procedures (n = 10). Technical and clinical success was achieved in all patients. There were two periprocedural complications (retroperitoneal bleed and septicemia) in the coronary/peripheral series and no complications in the peripheral/peripheral series. We also present five case reports to illustrate the utility of hybrid procedures in various clinical settings. This study suggests that the use of simultaneous or sequential minimally invasive procedures appears to be a safe and feasible strategy for the treatment of patients with symptoms from more than one vascular bed. Cathet Cardiovasc Intervent 2001;52:154–161.

Simplified Technique for Intraaortic Balloon Insertion

A simple technique for insertion and removal of an intraaortic balloon catheter is described. We have used it in 20 patients in the past six months, and the incidence of thrombi around the junction of the Dacron patch and the artery has been lessened. The prsence of a foreign body can be avoided also. We have not encountered any incidence or regional vascular compromise.

Prolonged Intraaortic Balloon Pumping in Klebsiella-Induced Hypodynamic Shock: Cardiopulmonary, Hematological, Metabolic, and Pathological Observations

Abstract We tested the hypothesis that intraaortic balloon pumping (IABP) might improve the cardiorespiratory, metabolic, and hematological responses of 20 mongrel dogs (10 IABP-treated, 10 controls) during 24 hours of live Klebsiella aerogenes -induced sepsis. At 24 hours after bacterial infusion, left ventricular stroke work was better preserved in the IABP-treated group of animals, 36.6 ± 3.3 gm-m (minus 25.4% of baseline value), compared with controls, 23.5 ± 4.2 gm-m (minus 50.1% of baseline value) ( p p Severe tissue damage was observed in the liver and small bowel of the control animals, while relatively less injury was seen in these organs in the IABP-treated group. Metabolic acidosis was also more marked in control animals compared with IABP-treated animals following Klebsiella infusion. In addition, the initial decrease in white blood cell count following bacterial administration was followed by a later increase in circulating leukocytes only in IABP-treated animals. Electron microscopic studies of the left ventricle showed only minor intracellular edema in both experimental groups, while left ventricular high-energy phosphate stores were maintained at similar levels in both groups. These findings suggest that the early institution of IABP may play an important palliative role in the treatment of hypodynamic gram-negative sepsis. It can be speculated that IABP provides additional time during which more specific therapy, including appropriate antibiotics, can be instituted in an effort to control the disease process before the development of irreversible cellular destruction.

Carbon Monoxide Accumulation during Extracorporeal Membrane Oxygenation for Acute Respiratory Failure

A marked increase in the carbon monoxide level in the blood sufficient to interfere with oxygen binding of hemoglobin was observed in a 43-year-old man during the course of extracorporeal membrane oxygenator support for acute respiratory failure from viral pneumonitis. The increased carbon monoxide level in this man was temporally related to the transfusion of large amounts of old bank blood. The etiology of an increased level of carbon monoxide in the blood during extracorporeal circulation is discussed and solutions to this problem are suggested.