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Biomedical subjects

S G Meister

Publications and source records attributed to S G Meister.

At least 37 records · Page 2Linked to original sources
PubMed1978

Effect of procainamide on induced ventricular tachycardia.

Ventricular extrastimulation was performed in 11 patients evaluated for chronic recurrent ventricular tachycardia, before and after a 1-gm procainamide infusion. Extrastimulation caused only nonsustained extra beats (less than 4) in 3 patients. Sustained tachycardia was induced in 7 patients in the basal state, of which 6 continued to have inducible tachycardia after procainamide was given (5.2 to 9.8 mg/L). The zone of coupling intervals that initiated tachycardia was unchanged or widened in these 6 patients because ventricular refractoriness was unchanged or because the tachycardia zone shifted to later diastole by an interval at least equivalent to the prolongation of ventricular refractoriness. Post-procainamide tachycardia cycle length was prolonged in all patients, by an average 51 msec. The one patient who responded to procainamide had a shortened ventricular refractory period, but the greatest slowing of tachycardia. Finally, sustained ventricular tachycardia could be induced in the eleventh patient only following procainamide administration, consistent with his clinical history. These results suggest that procainamide often may be ineffective in preventing sustained ventricular tachycardia, and that slowed conduction, rather than prolonged refractoriness, is the basis for the procainamide antiarrhythmic effect. Our data emphasize that antiarrhythmic drug effectiveness be evaluated in terms of effect on sustained arrhythmia rather than suppression of isolated ectopic beats.

Aged↗
PubMed1978

Electrophysiologic effects of hydralazine on sinoatrial function in patients with sick sinus node syndrome.

The electrophysiologic effects of hydralazine were evaluated in nine hypertensive patients with sinoatrial dysfunction. Intravenous hydralazine, 0.15 mg/kg, caused no significant reduction in arterial blood pressure. Yet this dose of hydralazine increased heart rate from 61.9 +/- 4.1 beats/min (mean +/- standard error of the mean) to 68.6 +/- 4.9 (P less than 0.001). Sinus nodal recovery time upon termination of atrial pacing shortened from 3,207 +/- 1,098 to 2,064 +/- 573 msec (P less than 0.05) and second escape cycles shortened as well (P less than 0.025). Acceleration of heart rate and abbreviation of recovery time did not closely correlate with change in blood pressure (r = 0.41 and 0.18, respectively). Junctional escape beats became more frequent and junctional escape time shortened from 2,525 +/- 692 to 1,705 +/- 382 msec (P less than 0.05). Sinoatrial conduction time tended to shorten, but a significant change was not observed. Atrial tachyarrhythmias did not occur and atrial refractoriness was unchanged. Thus, a minimal blood pressure response to hydralazine was associated with enhanced automaticity. Hydralazine merits clinical trial for treatment of sick sinus syndrome with concomitant hypertension.

Aged↗
PubMed1978

Ventricular extrastimulation in the mitral valve prolapse syndrome. Evidence for ventricular reentry.

Fourteen patients with mitral valve prolapse and essentially normal coronary arteries were evaluated for ventricular arrhythmias, utilizing programmed ventricular extrastimulation. Three were symptomatic with ventricular tachyarrhythmias. Application of appropriately timed ventricular extrasystoles initiated the tachyarrhythmias in these three patients. The remaining eleven mitral prolapse patients were apparently free of tachycardias. Repetitive ectopic beats were not induced by extrastimulation in these eleven patients. The initiation of ventricular tachyarrhythmias by extrastimulation suggests a reentrant mechanism for the ventricular ectopy of mitral valve prolapse.

Female↗
PubMed1978

The "R-on-T" phenomenon: an update and critical review.

The "R-on-T phenomenon" is the superimposition of an ectopic beat on the T wave of a preceding beat. Early observations suggested that R-on-T was likely to initiate sustained ventricular tachyarrhythmias. More recent experimental and clinical observations suggest that R-on-T is not a critical determinant of primary ventricular fibrillation in acute myocardial infarction; represents few of the initiating beats of paroxysmal ventricular tachycardia; and represents at worst only a small risk in terms of sudden death. Apparently when the capacity for sustained repetitive beating has not been clinically obvious, R-on-T is quite unlikely to result in ventricular tachyarrhythmias, even in the presence of coronary heart disease. However, in the setting of acute myocardial infarction, inability to always identify the precursors of tachyarrhythmias strengthens the argument for prophylactic treatment of patients.

Acute Disease↗
PubMed1978

Congenital coronary arteriovenous fistula: a diagnostic challenge.

This report describes a case of coronary arteriovenous (A-V) fistula involving both the right and the left coronary arteries. The venous component of the two circulations combines into a single channel that empties into the left ventricle just below the mitral valve.

Arteriovenous Fistula↗
PubMed1977

Knotting of a flow-directed catheter about a cardiac structure.

An instance of knotting of a flow-directed catheter about an intracardiac structure, presumably part of the tricuspid valve apparatus, is described. Because of the patient's severe pulmonary disease, cardiac surgery to remove the catheter was contraindicated. The central portion of the catheter was allowed to remain in situ, without apparent ill effects over a 16 month period.

Cardiac Catheterization↗
PubMed1977

Propranolol in mitral stenosis during sinus rhythm.

Patients with early symptomatic mitral stenosis usually suffer from pulmonary congestion on the basis of left atrial and pulmonary venous hypertension. They are often in sinus rhythm, and cardiac output is usually well maintained. Symptoms occur most often when heart rate, cardiac output, or both are increased. In this study, intravenous propranolol administered to patients with pure mitral stenosis in sinus rhythm resulted in significant reductions in mitral diastolic gradient (-7.1 mm. Hg +/- 1.6 SED), mean pulmonary wedge pressure (--6.9 mm. Hg +/- 1.2) and mean pulmonary artery pressures (--9.0 mm. Hg +/- 1.2). This was due to simultaneous reduction of heart rate (--13.0 beats/minute +/- 2.6 and cardiac output (--0.5 L./minute +/- 0.2). A small associated reduction of left ventricular systolic pressure (--5.1 mm. Hg +/- 2.6) was not accompanied by adverse clinical effects. A potential role for propranolol in medical management of pure mitral stenosis in the presence of sinus rhythm is suggested.

Adult↗
PubMed1977

The extent of supernormal ventricular excitability in man.

The supernormal period is an interval of increased excitability found in Purkinje fibers and thought to discretely neighbor T wave termination. Thereafter, excitability is thought to be constant. We examined the extent of the supernormal period in normokalemic patients at normal heart rates, determining excitability in terms of threshold voltages required for right ventricular bipolar excitation at 10-30 sec msec intervals of diastole. In sinus rhythm (ten patients), thresholds during maximal excitability (Emax) following the relative refractory period were only 5.2% +/- 0.1 less than late diastolic thresholds (P less than 0.05). However, a discrete change from supernormal to normal period was never demarcated. Instead, in each patient all thresholds fell within 95% confidence limits of the linear relation: Threshold = a volts/second + ThresholdEmax. In fact, five of ten patients showed constant or diminished excitability as diastole progressed. In ventricular drive (six patients), threshold was constant throughout diastole. A supernormal period was never seen. Thus, excitability changes were progressive throughout diastole after sinus beats, and diastolic excitability was constant after ventricular beats. T wave termination did not signal a discrete period of increased excitability analogous to the supernormal period of Purkinje fibers.

Adult↗
PubMed1977

Postextrasystolic T wave changes and angiographic coronary disease.

The significance of postextrasystolic T wave changes in beats following induced extrasystoles was assessed by angiography in 55 patients. These T wave changes were found in 81 per cent of coronary artery disease patients but also in 68 per cent of patients with normal coronary arteries (PNS). All patients with normal baseline electrocardiograms and normal coronary arteries showed postextrasystolic T wave changes. In electrocardiographic leads corresponding to the distribution of major coronary arteries, T wave changes occurred just as frequently when the artery was normal (54%) as when the artery was stenosed (55%). Left ventricular asynergy was not associated with an increased frequency of postextrasystolic T wave changes and in fact ejection fraction was greater end-diastolic pressure lower in patients with T wave changes. Thus, postextrasystolic T wave changes appear not to be useful in diagnosing or localising coronary artery disease.

Coronary Disease↗
PubMed1976

Potential artifact in measurement of left ventricular filling pressure with flow-directed catheters.

Artifactual pulmonary wedge pressure measurements were encountered during bedside use of Swan-Ganz catheters. These values were higher than pulmonary artery end diastolic pressure and devoid of typical phasic contours. Utilizing fluoroscopy these artifacts were reproduced by advancing the catheter tip 2-4 cm beyond the site of initial wedging and reinflating the balloon. Spurious increases of pulmonary wedge pressure of up to 15 mm Hg were thus obtained. In vitro catheter testing demonstrated overlapping of the catheter tip by the deformed balloon when it was fully inflated in a channel too small to accomodate it. These measurement artifacts are thus attributed to distal migration of the catheter tip into relatively small pulmonary artery branches and to subsequent occlusion of the catheter lumen by the balloon when it is reinflated. This can readily be avoided by routinely inflating the balloon with the minimum volume of air sufficient to yield a pulmonary wedge pressure tracing.

Blood Pressure↗
PubMed1976

Effect of lidocaine on right ventricular muscle refractoriness.

The effect of clinical doses of lidocaine on ventricular refractoriness was investigated in man. Effective refractory period (ERP) and functional refractory period (FRP) were determined in 11 normokalemic patients via a catheter at the right ventricular apex using programmed extra-stimuli and a ventricular electrogram recorded from the pacing catheter. No subject had recent ischemia or infarction. Measurements were repeated after clinical doses of lidocaine that produced therapeutic blood levels. Lidocaine caused no significant change in ERP or FRP during ventricular or atrial drive, or sinus rhythm with unchanged cycle length (CL). During sinus rhythm ERP/CL was unchanged. In 4 of 5 patients, lidocaine did not abolish echo phenomena observed during ventricular drive. This study demonstrates that ventricular refractoriness can be safely measured in man. Clinical doses of lidocaine did not alter right ventricular refractory periods. Lidocaine action is not explained by alteration of ventricular refractoriness, at least in muscle remote from the site of acute infarction.

Aged↗
PubMed1976

Tachycardia upon swallowing. Evidence for a left atrial automatic focus.

Evaluation of a patient with tachycardia upon swallowing offers evidence of its origin from the left atrium. The tachycardia appears to arise from an automatic focus discharged after mechanical stimulation by the esophagus. Despite a left atrial origin for this arrhythmia, it does not fulfull previously described electrocardiographc criteria for "left atrial rhythms."

Action Potentials↗
PubMed1976

Sustained haemodynamic action of nitroglycerin ointment.

Intravenous vasodilators have been shown to improve the haemodynamic status of patients in congestive heart failure. However, neither intravenous nor sublingual preparations are suitable for chronic administration or use in ambulatory patients. In this study, nitroglycerin ointment bas administered to 11 patients in congestive heart failure. Mean pulmonary wedge and arterial pressures, as well as systemic blood pressures and heart rate were then monitored for 2 to 5 hours and compared with baseline values. Pulmonary wedge and arterial pressures, as well as systemic systolic arterial pressure, decreased significantly at 15 minutes after application and remained depressed for up to 5 hours. Systemic diastolic pressures fell significantly at 30 minutes and also remained significantly reduced for up to 5 hours. Thus, nitroglycerin ointment may be suitable for chronic vasodilator therapy of congestive heart failure.

Adult↗
PubMed1975

Appraisal of sinus node artery disease.

The relationship of depressed sinus node function to coronary artery disease (CAD) was evaluated. The sinus node artery (SNA) was easily identified in all of 80 unselected normal coronary arteriograms. Angiographic disease of, or significant obstruction proximal to, the SNA was seen in 21% of 80 unselected CAD patients. Heart rate and sinoatrial recovery times (SART) were obtained in 50 consecutive unmedicated patients prior to arteriography. There was no difference between the SART of 23 CAD patients free of SNA involvement (1092 msec +/- 55 sem) and 18 normals (1070 +/- 40 msec). Nine patients with SNA involvement had shorter SART (941 +/- 52 MSEC) than normals (P less than 0.05) or other CAD patients (NS). Similar results were obtained for heart rate. No patient with SNA involvement had a prolonged SART or sick sinus syndrom (SSS). six of the 50 patients studied were symptomatic with SSS. Five of these SSS patients had CAD but none had angiographic evidence of SNA involvement. Obstructions involving the SNA were common in CAD but were not associated with altered heart rate or SART. Patients with SSS exhibited no angiographic evidence of SNA involvement. Therefore, it is unlikely that SSS is related to CAD of the SNA.

Adult↗