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Biomedical subjects

R C Klein

Publications and source records attributed to R C Klein.

At least 55 records · Page 3Linked to original sources
PubMed1987

Blood pressure monitoring for assessing the duration of action of antihypertensive treatment.

The duration of antihypertensive action of the alpha-adrenergic blocking agent, prazosin, was studied in 12 hypertensive patients in whom twice-daily doses of this agent were found to be effective and well tolerated during a preliminary titration period. The patients then entered a cross-over phase of study. On a randomized basis, they were given prazosin either twice daily for eight weeks followed by an eight-week period in which they received the same total dose once daily (each morning), or they were given the treatment for a once-daily period followed by a twice-daily period. Using the conventional sphygmomanometer, there were no significant differences in blood pressures for the patients as a whole between the measurements during once-daily dosage (measured approximately 24 hours after the last administration of drug) and those during twice-daily dosage (measured approximately 12 hours after the last administration); but for both methods of administration, blood pressures were significantly lower than pre-treatment values. Automated whole-day ambulatory blood pressure monitoring showed a tendency for blood pressures to be lower with once-daily than with twice-daily treatment during the first 12 hours after the morning doses were given, but there was a reversal of this pattern during the early morning hours preceding the next dose. However, for at least half of the patients these differences were only minimal. Thus, prazosin may be effective in some patients as once-daily treatment, especially after several weeks of therapy. Moreover, automated whole-day blood pressure monitoring appears to be a valuable technique for guiding dosage requirements for patients on an individual basis.

Adult↗
PubMed1987

Enhanced antiarrhythmic efficacy of propafenone when used in combination with procainamide or quinidine.

This study evaluated the efficacy and safety of combining propafenone with procainamide or quinidine for treating ventricular arrhythmias in patients in whom procainamide or quinidine therapy alone failed to suppress arrhythmias. In 30 patients, the addition of propafenone resulted in a significant reduction of premature ventricular contraction (PVC) frequency compared to drug-free baseline (406 PVC/hr vs 33, p less than 0.001) and to procainamide or quinidine monotherapy (211 PVC/hr vs 27, p less than 0.01). Propafenone alone was also more effective than either procainamide or quinidine and resulted in significant suppression of PVC compared to the drug-free state (406 PVC/hr vs 38, p less than 0.001). However, higher propafenone doses were necessary during monotherapy as compared to propafenone therapy combined with procainamide or quinidine (730 mg/day vs 480 mg/day, p less than 0.001). Of the 30 patients, 22 required an increase in propafenone dose during monotherapy as compared to combination therapy. Thus, propafenone is an effective antiarrhythmic agent when used in combination with type IA antiarrhythmic drugs. With these combinations, lower doses of propafenone can be utilized effectively than with propafenone alone.

Adult↗
PubMed1987

Absence of differential inhibition of thromboxane A2 and prostacyclin by low and high dose aspirin in coronary artery disease.

This study assessed the effect of low (40 mg) and high (324 mg) single dose aspirin on cardiac release of thromboxane A2 and prostacyclin as assessed by measurement of coronary sinus levels of metabolites in patients with coronary artery disease. Measurements were done in the resting state and in the presence of pacing stress prior to and 24 h after aspirin administration. There was no consistent response in prostaglandin release under conditions of tachycardia stress as compared to control. Following both doses of aspirin, thromboxane could not be detected at rest or with pacing, and prostacyclin metabolic levels were undetectable in six of seven patients. Prostaglandin levels were not related to myocardial lactate extraction or production and lactate levels had no consistent relationship to aspirin administration. These data indicate that both low and high doses of aspirin inhibit both thromboxane A2 and prostacyclin production in humans. Selective thromboxane inhibition might not be possible.

6-Ketoprostaglandin F1 alpha↗
PubMed1986

Efficacy and safety of oral cibenzoline for ventricular arrhythmias.

This study evaluates acute and chronic therapy with cibenzoline, a new class I antiarrhythmic drug, in 49 patients with ventricular arrhythmias. Acute therapy with 260 to 330 mg/day of cibenzoline resulted in a significant reduction in the number of hourly ventricular premature complexes (VPCs) (from 377 +/- 60 to 116 +/- 33, p less than 0.001), total paired VPCs in 24 hours (from 531 +/- 196 to 101 +/- 66, p less than 0.02), and total episodes of ventricular tachycardia in 24 hours (from 31 +/- 10 to 4 +/- 3, p less than 0.01). Among this group, acute therapy resulted in more than 75% suppression of VPC frequency in 29 of 49 patients, more than 90% suppression of paired VPCs in 31 of 42 patients, and complete suppression of ventricular tachycardia in 21 of 27 patients. Radionuclide evaluation of ventricular function revealed no deleterious effect of cibenzoline on ventricular function. Significant suppression of VPC frequency was maintained during 6 months of therapy in 16 of 19 patients and during 12 months of therapy in 9 of 10 patients. Trough plasma cibenzoline levels were measured during the acute dosing period. These levels did not differ among the group of responders (326 +/- 140 ng/ml) compared with nonresponders (354 +/- 282 mg/ml). Cibenzoline therapy resulted in adverse effects 18 patients and necessitated discontinuing therapy in 12. No patient had a proarrhythmic effect. In conclusion, cibenzoline appears to be as efficacious as the available antiarrhythmic drugs in treating chronic complex ventricular arrhythmias. Drug-related adverse effects occur with a frequency similar to that of other antiarrhythmic drugs.

Administration, Oral↗
PubMed1984

Ventricular arrhythmias in aortic valve disease: analysis of 102 patients.

Frequency and grade of ventricular arrhythmias in patients with isolated aortic stenosis (AS) or regurgitation (AR) were determined by 24-hour ambulatory electrocardiographic monitoring. The occurrence of ventricular arrhythmias in patients with aortic valve disease was compared with that in matched control subjects without aortic valve disease. Complex arrhythmias were significantly more prevalent in patients with valve disease than in control subjects (40 of 102 vs 19 of 102); the significant difference occurred in patients without concomitant coronary artery disease (CAD). In patients with valve disease without CAD, complex arrhythmias were significantly more common than in normal control subjects (22 of 65 vs 4 of 64); in the presence of CAD, complex arrhythmias were as prevalent in those with aortic valve disease as in those without it (18 of 37 vs 15 of 37, respectively). Among patients with AS or AR, arrhythmia occurrence and grade of ventricular ectopic activity were not related to the degree of AS or AR, ventricular hemodynamics or the presence or absence of concomitant CAD.

Adult↗
PubMed1984

Electrocardiographic diagnosis of left ventricular hypertrophy in the presence of left bundle branch block.

The presence of left bundle branch block (LBBB) on 12-lead ECG may obscure the diagnosis of other ECG abnormalities including left ventricular hypertrophy (LVH). We retrospectively reviewed ECGs of patients with LBBB and LVH as determined by echocardiography to evaluate several ECG parameters as predictors of LVH. ECG evaluation included precordial voltage as measured by the sum of the S wave in leads V1 or V2 plus R wave in lead V6, QRS duration, mean frontal plane QRS axis, R wave amplitude in lead aVL, intrinsicoid deflection, and the presence or absence of criteria for left atrial enlargement. In the presence of LBBB and LVH, precordial voltage was significantly greater (p less than 0.001), QRS duration more prolonged (p less than 0.001), and left atrial enlargement more frequently present (p less than 0.001) than when LVH was not present. There was no difference in limb lead voltage, intrinsicoid deflection, or mean frontal plane QRS axis. Furthermore, the criterion of SV2 + RV6 greater than 4.5 mV demonstrated a sensitivity of 86% and a specificity of 100%. We conclude that a voltage criterion of SV2 + RV6 greater than 4.5 mV is diagnostic of LVH in the presence of LBBB; furthermore, QRS duration of greater than 160 msec plus left atrial enlargement strongly supports the diagnosis of LVH.

Bundle-Branch Block↗
PubMed1984

Effects of indomethacin on pleural pain.

Indomethacin (50 mg every eight hours) was given to 17 selected patients with pleurisy to control pain. Eleven of 17 obtained good to excellent relief of pain within 24 hours. Pain was not relieved in three patients and was only partly relieved in three others. Potentially serious side effects developed in two patients but resolved quickly. In selected patients indomethacin appears to be a reasonable initial choice for relief of pleural pain.

Adult↗
PubMed1981

Evaluation of the effects of systemic nitroglycerin on perfusion of ischemic myocardium in coronary heart disease assessed intraoperatively by antegrade blood flow through intact saphenous vein bypass grafts.

To evaluate systemic nitroglycerin (NTG) effects on reduced perfusion of ischemic myocardium in coronary disease, intravenous NTG actions on coronary circulatory dynamics were directly assessed intraoperatively during aortocoronary bypass surgery in 24 patients. Thus metered antegrade blood flow was measured through 56 separate intack saphenous vein bypass grafts to analyze NTG perfusion response in the obstructed native coronary artery (CA). In 34 bypassed CA with proximal luminal diameter narrowing greater than 50% to 90%, NTG reduced (p less than 0.01) graft flow (GF) 82 to 63 cc/min, thereby indicating that NTG dilated proximal stenoses with resultant increased CA flow. In 11 bypassed CA obstructed greater than 90% to 100% with well developed collaterals distally, NTG decreased (p less than 0.05) GF 64 to 53 cc/min, thus indicating enhanced collateral flow. In contrast, in 11 bypassed CA obstructions greater than 90% to 100% without collaterals, that NTG increased (p less than 0.02) GF 91 to 100 cc/min indicated NTG nonresponsiveness of the severely diseased CA. Thus systemic NTG improves perfusion to ischemic myocardium subserved by diseased coronaries with less than 90% stenosis or by greater than 90% obstructed vessels with substantial collaterals distally.

Adult↗
PubMed1979

Recent advances in programmable pacemakers. Consideration of advantages, longevity and future expectations.

The important electrical characteristics of conventional ventricular demand pacemakers currently widely employed are unable to be altered by noninvasive means after their implantation. However, a number of domestic pacemaker manufacturers have started to introduce a new modality for atraumatic modulation of these devices, the fully programmable pacemaker system, whereby the several variables regulating pacemaker operation may be optimized on an individual basis according to need. Such programmable pacemaker functions which can be varied include rate, energy output, refractory period and sensing threshold. The indications, significance and mechanisms for control of the various function programming are delineated for physician understanding at the present time.

Arrhythmias, Cardiac↗
PubMed1978

Papillomatosis of the respiratory tract. Upper airway obstruction and carcinoma.

Metastasizing squamous cell carcinoma of the lung developed in a patient who had juvenile papillomatosis but had had no previous radiation therapy. At the same time, a significant upper airway obstruction was present. All endobronchial lesions rapidly resolved with radiation therapy, and the carcinoma was resected.

Adolescent↗
PubMed1978

Influenza, respiratory distress and clear chest films: report of four cases.

Four patients developed severe wheezing and dyspnea with clear chest films during the course of an influenza epidemic. A variety of factors appeared to play a role in the pathogenesis of the respiratory distress. Standard bronchodilator therapy produced no appreciable response. All patients did well with supportive care.

Adult↗
PubMed1978

Incremental intravenous nitroglycerin for control of afterload during anesthesia in patients undergoing myocardial revascularization.

In 25 patients undergoing coronary artery bypass grafting hemodynamic measurements (including values obtained with Swan-Ganz catheterization in 21 of the patients) were made before and after administering a bolus injection of 64 or 96 mcg of nitroglycerin to relieve intraoperative hypertension. This pharmacological agent reduced afterload and preload without raising heart rate. The effect was apparent within 1-3 min and lasted 5-10 min. Untoward hypotension was not encountered in any instance. This intervention appears to be a safe approach to the treatment of intraoperative hypertension in patients with coronary artery disease.

Adult↗