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Biomedical subjects

C B Hantler

Publications and source records attributed to C B Hantler.

31 records · Page 2Linked to original sources
PubMed1988

Cardiac electrophysiologic interactions of bepridil, a new calcium antagonist, with enflurane, halothane, and isoflurane.

Bepridil is an investigational calcium antagonist that also has fast sodium channel blocking and antidysrhythmic properties. In the present study, the potential interactions of bepridil with volatile anesthetics on cardiac electrophysiologic parameters were evaluated in open-chest dogs. Twenty-four dogs anesthetized with enflurane (n=6), halothane (n=6), isoflurane (n=6), or chloralose (n=6) received 2.5 mg/kg of bepridil intravenously (IV). Twenty-five additional dogs anesthetized with enflurane (n=7), halothane (n=6), isoflurane (n=6), or chloralose (n=6), received bepridil, 5.0 mg/kg, IV. Dogs anesthetized with cloralose served as controls. Cardiac electrophysiologic parameters were measured after the dogs were anesthetized and were repeated 5, 15, 30, 45, and 60 minutes after bepridil infusion. Plasma bepridil concentrations were also determined at the above time points. Synergy between bepridil and enflurane was demonstrated in the following cardiac electrophysiologic parameters: depression of sinus node function as evidenced by severe depression of sinus node automaticity and conduction; depression of atrioventricular function as evidenced by prolongation of the atrial-His bundle interval and the Wenckebach R-R interval; and, prolongation of the atrial effective refractory period. No synergy was demonstrated between bepridil and halothane or isoflurane when compared to bepridil's effects during chloralose anesthesia. It is concluded that significant synergistic cardiac electrophysiologic effects exist between bepridil and enflurane in dogs. It is recommended that caution be used when anesthetizing patients receiving bepridil with enflurane until human data on the use of this combination of pharmacologic agents is available.

Anesthetics, Inhalation↗
PubMed1987

Catheter ablation of ventricular tachycardia with intracardiac shocks: results in 33 patients.

Catheter electrical ablation of ventricular tachycardia (VT) was attempted in 33 patients who had recurrent unimorphic VT refractory to 3.7 +/- 1.2 (mean +/- SD) antiarrhythmic drugs. Their mean age was 56 +/- 14 years. Twenty-two patients had coronary artery disease, six had other types of heart disease, and five had no structural heart disease. The mean left ventricular ejection fraction was 0.34 +/- 0.17. Thirty patients had only one documented morphologic type of spontaneous VT, whereas three patients had more than one. One to four shocks of 100 to 300 J each were delivered to the endocardial exit site of VT, as identified by endocardial activation mapping and pace-mapping. In each patient endocardial activation at the exit site of VT preceded the onset of the QRS complex (mean activation time -50 +/- 30 msec). Pace-mapping was possible in 26 patients, and in all but two patients the QRS complexes during VT and during pacing at the exit site of VT were very similar in at least 10 of 12 electrocardiographic leads. In 29 patients, shocks were delivered between an endocardial electrode (cathode) and a patch electrode on the chest wall (anode). Seven patients (including three who first received shocks using an external anode) whose VT originated in the septum received transseptal shocks between two electrodes positioned on either side of the septum. The procedure was successful in 15 patients (45%), who had no recurrence of VT either on no antiarrhythmic therapy or on the same regimen that was ineffective before ablation, over a follow-up period of 15.5 +/- 10 months (range 5 to 35). The ablation attempt was unsuccessful in 18 patients (55%). There were no significant differences in clinical and electrophysiologic variables between patients with and without a successful outcome. Seven nonfatal complications occurred in six patients: sustained nonclinical VT immediately after the shock, ventricular fibrillation on days 5 and 6 after ablation, neurologic deficits (n = 2), atrioventricular block (n = 2), and brachial artery thrombosis. In conclusion, catheter electrical ablation of VT has modest efficacy and is relatively safe in a selected group of patients who have predominantly one configuration of unimorphic VT.

Cardiac Catheterization↗
PubMed1987

Effects of isoflurane on myocardial blood flow, function, and oxygen consumption in the presence of critical coronary stenosis in dogs.

Because isoflurane has been reported to produce coronary steal, we studied 12 open chest, anesthetized (pentobarbital) dogs with critical stenosis (CS) of the left circumflex coronary artery (LCA). Sonomicrometers were implanted to measure systolic wall thickening, myocardial blood flow (MBF) was measured with microspheres (15 microns diameter), and regional venous sampling was performed to estimate regional oxygen extraction and myocardial oxygen consumption (MVO2). Anesthetic concentrations of isoflurane reduced arterial blood pressure dramatically, resulting in a maldistribution of MBF distal to the CS consistent with the pattern characterizing a transmural coronary steal effect. Elevation of arterial blood pressure with phenylephrine during high concentration isoflurane (1.7 +/- 0.1%) augmented MBF, but the maldistribution distal to the CS persisted. Despite the maldistribution, however, there was no indication of ischemia in the LCA region because systolic wall thickening, oxygen extraction, and MVO2 were not significantly different between the LCA and left anterior descending coronary artery (LAD) (control) areas. Because wall thickening, oxygen extraction, and MVO2 were markedly reduced by isoflurane in both the LCA and control areas, it was concluded that isoflurane substantially reduced myocardial oxygen requirements by inducing myocardial depression, reducing heart rate, and decreasing afterload. Consequently, the apparent maldistribution of LCA blood flow (coronary steal) was due to the hemodynamic and vasodilatory effects of isoflurane, but did not result in ischemia because the level of blood flow was at or above the requirements of the myocardium.

Animals↗
PubMed1986

Protamine pretreatment attenuation of hemodynamic and hematologic effects of heparin-protamine interaction. A prospective randomized study in human beings undergoing aortic reconstructive surgery.

Hemodynamic and hematologic responses to protamine sulfate reversal of heparin's anticoagulant effects were studied in 15 consecutive randomized patients undergoing aortic reconstructive surgery. In a double-blinded manner, patients were pretreated with either normal saline solution (n = 8) or protamine (0.75 mg/kg/3 min, n = 7) 5 minutes before heparinization (150 IU/kg). After aortic grafts were placed, protamine (1.5 mg/kg/3 min) was administered intravenously to reverse the heparin. Arterial blood pressure, heart rate, pulmonary artery and capillary wedge pressure, central venous pressure, and cardiac output were monitored, as were platelet count, white blood cell count, activated clotting time, total hemolytic complement levels, and C3a levels. Calculated parameters included systemic vascular resistance and pulmonary vascular resistance. Pretreatment with protamine compared with saline solution prevented the hypotension (+6 vs. -16 mm Hg, p less than 0.05) and declining pulmonary artery pressure (+1 vs. -7 mm Hg, p less than 0.01) observed with protamine reversal of heparin. Significant differences between the two groups in central venous pressure and pulmonary vascular resistance were of less clinical relevance. Protamine pretreatment lessened the thrombocytopenia found during reversal compared with saline-pretreated patients although the difference was not statistically significant. Minimal hypotension occurring after protamine pretreatment alone was not accompanied by hemodynamic or hematologic changes, other than decreased heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1986

Attenuation of hemodynamic and hematologic effects of heparin-protamine sulfate interaction after aortic reconstruction in a canine model.

This investigation documented the effect of protamine sulfate pretreatment on the adverse hemodynamic and hematologic sequela of rapid intravenous protamine administration in heparinized dogs having undergone prior implantation of aortic prostheses. Fourteen dogs underwent infrarenal aortic replacement with 6 mm inner diameter by 7 cm knitted Dacron double-velour grafts. Carotid arterial, central venous, and pulmonary arterial catheters were placed for continuous hemodynamic monitoring. All dogs were adequately anticoagulated with heparin (150 IU/kg) and reversed with protamine (1.5 mg/kg/10 sec) after graft insertion. Pretreatment regimens studied included normal saline (n4), protamine 0.75 mg/kg (n5), and protamine 2.25 mg/kg in three divided doses of 0.75 mg/kg each (n5). All pretreatment agents were administered 3 minutes before heparinization. Blood pressure (BP), heart rate (HR), pulmonary artery pressure (PAP) and cardiac output (CO) were measured. Hematologic assessments included platelet count (PC), leukocyte count, thrombin clotting time, and total hemolytic complement. Significant salutory effects were associated with protamine pretreatment regarding BP, HR, PAP, CO, and PC. It is concluded that adverse hemodynamic effects of protamine reversal are blocked and certain hematologic effects are reduced with protamine pretreatment before heparinization and its reversal in this canine experimental model.

Animals↗
PubMed1981

Use of pentolinium in postoperative hypertension resistant to sodium nitroprusside.

Five patients with systemic arterial hypertension occurring in the postoperative period and resistant to sodium nitroprusside are described. The hypertension was associated with evidence of increased activity of the autonomic and renin-angiotensin systems. Sympathetic blockade using the ganglion blocking agent, pentolinium, enabled the arterial pressure to be controlled adequately in all patients. This was associated with a decrease in catecholamine concentrations, plasma renin activity and angiotensin II concentrations.

Adult↗
PubMedDate not supplied

Achievement of physiologic pulsatile flow on cardiopulmonary bypass with a 24 French cannula.

In 1990, the NIH formally recognized the need for investigation of the problem of damaging the effects of cardiopulmonary bypass, issuing RFA HL-90-12-H, which emphasized production of neurologic defects in the very young and the elderly. The authors were at that time involved in comparison of pulsatile flow to steady flow cardiopulmonary bypass in large ungulates. The world literature recognizes five damaging effects of steady flow cardiopulmonary bypass that can be mitigated by pulsatile flow: metabolic acidosis, interstitial fluid accumulation, elevated systemic vascular resistance, arteriovenous shunting, and impaired brain oxygenation. To maximize the beneficial effect of pulsatile flow, however, it is necessary that its morphology be physiologic. It has been stated in the past that this goal may not be possible using standard size aortic cannulas. The purpose of this publication is to describe a method by which this feat has been achieved in 150 pound ungulates undergoing prolonged cardiopulmonary bypass.

Animals↗
PubMedDate not supplied

Changes in brain pH, PO2, PCO2, cerebral blood flow, and blood gases induced by a hyperosmolar oxyreplete hemosubstitute during cardiopulmonary bypass.

Eleven goats (mean weight, 69 +/- 16 kg) underwent 5 hrs of normothermic nonpulsatile cardiopulmonary bypass (CPB) using as priming fluid either a Ringer's based crystalloid priming solution (CP, n = 5) of a hyperosmolar oxyreplete hemosubstitute (HS, n = 6). The HS contained 20% w/v perfluorocarbon (perfluorodecalin), its osmolarity was 800-900 mOsm/1, and the administered dose of perfluorocarbon was 30-50 ml/kg. Otherwise, the experimental procedure was identical for both groups. PaCO2 was maintained above 35 mmHg and blood flow rate at 65 ml/kg. Brain tissue pH, PO2, and PCO2, cerebral blood flow (CBF), arterial and venous blood gases, and other systemic variables were monitored. During CPB, PVO2 and brain tissue PO2 were increased significantly in the HS group. The CBF per kilogram of weight also was significantly higher in the HS group. Metabolic acidosis developed in both groups and, surprisingly, brain tissue pH and pHV were lower in the HS group. The mean values of PVCO2 and brain tissue PCO2 indicate that brain tissue hypercapnia also occurred in both groups. The HS provided long-term stability and compatibility with electrolytes, and did not cause major complications or allergic reactions during CPB. Perfluorocarbon based HSs improve tissue oxygenation, eliminate the risk of infection due to homologous transfusions, do not require blood type matching, have a shelf life longer than that of blood, and, therefore, they can be an important factor in diminishing the incidence of complications after CPB.

Animals↗