Biomedical subjects

M M Laks

Publications and source records attributed to M M Laks.

At least 109 records · Page 6Linked to original sources

PubMed1975

Cardiorenal effects of lidocaine and procaine amide in the conscious dog.

Simultaneous measurements of hemodynamics, arterioventricular (AV) conduction, and renal functioner were obtained in conscious dogs. Catheters were implanted for the long-term measurement of central aortic, right ventricular, and pulmonary artery pressure. AV conduction was assessed following surgical implantation of multipolar electrode plaques in the area of the bundle of His, as well as on the epicardium of the right and left atria and ventricles. Renal function was assessed utilizing standard techniques. Following control measurements, lidocaine, 1 mg/kg, or procaine amide, 10 mg/kg, was administered intravenously. Subsequently, serial measurements were obtained for a 90-min period. No significant changes in hemodynamics were observed following either drug. Procaine amide produced a significant increase in heart rate and a minimal increase in QRS duration associated with a decrease in low right atrial to His bundle conduction time. However, no significant changes in cardiac conduction were observed after lidocaine administration. Renal function was unaffected by lidocaine but significantly depressed by procaine amide, as demonstrated by a decrease in GFR and effective renal flow. In summary, acute administration of procaine amide significantly alters renal function in the conscious dog with minimal effects on AV conduction and hemodynamics.

Aminohippuric Acids↗

PubMed1975

Preparation for repeated study of left ventricular function in the conscious dog.

A method is presented for a relatively simple nontraumatic chronic left heart catheter preparation for the study of left ventricular hemodynamics in the conscious dog. In 30 dogs an 8 Fr Cordis catheter was modified and implanted into the left ventricle via the right atrial septum. Transseptal catheterization was performed without significant morbidity and mortality. Left ventricular cineangiograms and pressures and cardiac outputs have been repeatedly performed on fully conscious dogs with no apparent discomfort displayed by the dog.

Animals↗

PubMed1975

An electrocardiographic pattern of acute myocardial infarction associated with excessive use of aerosolized isoproterenol.

A 39-year-old women inhaled approximately 675 mg of aerosolized isoproterenol in less than three days during an asthmatic attack. Serial enzyme and ECGs were consistent with acute myocardial necrosis. During a three-year-followup period, no clinical evidence or predisposing factors for coronary artery disease were revealed. The close temporal relation of isoproterenol overdosage with mycardial necrosis provides presumptive evidence that the well-documented association of myocardial necrosis with high dosage catecholamines in animals may also occur in man. While in no way detracting from the value of isoproterenol in standard doses, this report alerts physicians to the possibility of another hazard in those who may use this drug to excess.

Acute Disease↗

PubMed1975

Atrioventricular nodal reentry in the Wolff-Parkinson-White syndrome.

Wolff, Parkinson, and White, in their initial description of the syndrome that bears their names, emphasized the association of tachycardias with the electrocardiographic abnormality. Subsequent investigations have identified, both anatomically and electrophysiologically, that dual pathways of atrioventricular (AV) conduction exist. Furthermore, experimental and clinical evidence has stressed that the mechanism of tachycardia production in the syndrome appears to reentry utilizing these dual pathways. However, recent studies have emphasized that other mechanisms of tachycardia production may be responsible for the arrhythmias seen in this syndrome. The present report identifies that AV nodal reentry may be the sole mechanism for tachycardia induction in the Wolff-Parkinson-White (WPW) syndrome. This finding may be of great clinical significance in light of the availability of surgical therapy for WPW patients with intractable arrhythmias.

Adolescent↗

PubMed1975

Acute pulmonary artery hypertension produced by distention of the main pulmonary artery in the conscious dog.

In order to delineate further the function of the main pulmonary artery as a receptor site, a specially designed Laks triple-lumen balloon catheter was inserted transvenously and positioned in the main pulmonary artery. In six conscious nonsedated dogs, inflation of a balloon in the main pulmonary artery produced acute reversible pulmonary arterial hypertension; the pressure beyond the balloon increased from a mean of 21/6 mm Hg to 43/14 mm Hg (P less than 0,001). This observed pulmonary hypertension occurred at an amount of balloon inflation which produced an increase in right ventricular systolic pressure (P less than 0.001), but no significant change occurred in cardiac output (P greater than 0.05) or right ventricular end-diastolic pressure (P greater than 0.1). Left atrial and pulmonary artery wedge pressures did not change or decreased slightly (P greater than 0.1 and P greater than 0.1, respectively). The calculated pulmonary vascular resistance increased (P less than 0.001), while the calculated systemic vascular resistance did not chang (P greater than 0.04). Therefore, we postulate that distention of the main pulmonary artery in the conscious dog reflexly produces constriction of pulmonary arterioles, and possibly venules, due to excitation of receptors probably located in the wall of the pulmonary artery or possibly the right side of the heart, or both.

Animals↗

PubMed1975

Prolongation of the tachycardia zone: a possible mechanism for medical failure in paroxysmal supraventricular tachycardia.

Paroxysmal supraventricular tachycardia in man has been considered to be due to either development of reentry utilizing AV junctional tissue or the presence of an ectopic pacemaker located within the atrium. Most contemporary information suggests that AV junctional reentry is the dominant mechanism for this arrhythmia in man. This present study identifies that the frequence of tachycardia episodes may be correlated with the width of a tachycardia zone as determined by the atrial extrastimulus technique. Moreover, pharmacological therapy directed toward the elimination of this arrhythmia can be assessed utilizing this atrial stimulation technique. Findings in this present study identify that, in patients with widened tachycardia zones, propranolol therapy may not be efficacious. This latter finding is no contrast to the previous observations suggesting that propranolol therapy is the drug of choice for reentrant arrhythmias in man.

Atrioventricular Node↗

PubMed1974