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Biomedical subjects

W Markiewicz

Publications and source records attributed to W Markiewicz.

88 records · Page 5Linked to original sources
PubMed1976

Normal myocardial contractile state in the presence of quinidine.

Since quinidine is one of the few agents available to treat and prevent ventricular arrhythmias in ambulatory patients, its hemodynamic effects have been reevaluated. When given in therapeutic doses to anesthetized mongrel dogs, quinidine significantly reduced heart rate, aortic pressure and flow, but it did not significantly change the first derivative of the left ventricular pressure curve (left ventricular dp/dt) in nine dogs. A subsequent group of dogs was studied after vagotomy and practolol administration to block cardiac reflexes. This group showed significant reductions in heart rate, aortic pressure and left ventricular dp/dt, with the latter returning to predrug control values when preload, afterload and heart rate were maintained constant. These studies suggest that quinidine does not directly affect myocardial contractility when given in therapeutic doses. Furthermore, the reduction in heart rate in these animals provides support for a direct depressant effect of quinidine on the sinus node. The adverse effects of quinidine on cardiac function previously reported may be due to the use of toxic doses or are secondary to quinidine peripheral circulatory effects, rather than due to a direct reduction in cardiac contractile state.

Animals↗
PubMed1976

Mitral valve prolapse in one hundred presumably healthy young females.

Clinical, electrocardiographic, phonocardiographic, and echocardiographic examinations were performed in 100 presumably healthy young females. Treadmill testing and ambulatory electrocardiographic monitoring were performed in a selected group of these subjects. Phonocardiograms, recorded with the subjects supine at rest, after inhalation of amyl nitrite, and in the upright position, revealed a 17% incidence of nonejection clicks and/or late or mid- to late systolic murmurs (PHONO-MSCLSM). Echocardiographic studies were performed in the second, third, fourth, and fifth intercostal space with emphasis on the importance of transducer angulation on the chest. Studies obtained with the transducer perpendicular to the chest in the sagittal plane, or pointing cephalad at a time when both mitral leaflets and left atrium are recorded, are optimal to study the mitral valve systolic motion. With the transducer in this position, 21 subjects were found to have pansystolic or late systolic prolapse, as previously defined on the echocardiogram. The presence of these echocardiographic findings was statistically related to the presence of PHONO-MSCLSM. Other echocardiographic patterns were identified and their relation to PHONO-MSCLSM and transducer position is discussed. Ten subjects with both echocardiographic evidence of mitral valve prolapse and PHONO-MSCLSM were identified (group EP), while 18 other subjects had either echocardiographic or phonocardiographic findings suggestive of mitral valve abnormality (group EorP). Seventy-two subjects had no abnormality (group noEP). The incidence of various clinical, electrocardiographic, and echocardiographic findings in these three groups was determined. Some findings said to be common in patients with proven mitral valve prolapse were seen more frequently in group EP subjects. Echocardiographic and phonocardiographic findings suggesting mitral valve abnormalities were found more commonly than expected in a population of presumably healthy young females.

Adolescent↗
PubMed1976

Problems in assessing infarction size by epicardial mapping: preliminary studies with quinidine.

Some of the laboratory difficulties in assessing infarction size produced by intermittent coronary artery occlusion were demonstrated by using an epicardial mapping technique in anesthetized open-chest dogs. Intermittent occlusion of a left anterior descending coronary artery branch resulted in a marked elevation of the ST segment above the baseline in the areas of the myocardium supplied by this vessel. Repeated occlusions after administration of normal saline as a control produced less ST-segment elevation thn that noted during control occlusions; however, repeated occlusions after infusion of quinidine produced a further lessening in ST-segment elevation. The problems encountered in interpreting these results are emphasized. Long-term coronary occlusion studies were performed in order to correlate epicardial electrograms with histological findings of ischemia or myocardial necrosis. Our investigations show that epicardial mapping tended to underestimate the area of injury, and this limits the interpretation of drug intervention studies such as those in which quinidine is administered. Therefore, caution should be exerted when using epicardial mapping techniques to assess the effect of various pharmacological interventions on infarction size in open-chest dogs.

Animals↗
PubMed1976

Effect of transducer placement on echocardiographic mitral valve systolic motion.

The influence of transducer position and angulation upon the mitral systolic echo was studied in 100 presumably healthy females. Echocardiographic studies were performed from the second, third, fourth and fifth intercostal spaces (ICS). The role of the sound beam's path relative to cardiac motion was assessed by analyzing the recorded mitral valve pattern as a function of transducer orientation, independent of the absolute ICS used. With the transducer directed caudally when both mitral leaflets and left atrium were recorded, holosystolic or midsystolic posterior motion of the mitral valve leaflet echo was seen in 59% of the subjects. These patterns, recorded this way, were not related to phonocardiographic signs suggesting mitral valve prolapse. Best correlation with phonocardiographic findings was obtained when the echocardiographic examination was performed with the transducer either perpendicular to the chest in the sagittal plane, or pointing slightly cephalad ('perpendicular' position). With the transducer in 'perpendicular' position, both holosystolic and midsystolic posterior motion of the mitral systolic echo, deviating more than 2 mm from a line joining the C and D points, were highly related statistically to phonocardiographic findings suggesting mitral valve prolapse. This study demonstrates that transducer position and angulation on the chest wall are important determinants of echocardiographic appearance of mitral valve during systole. Only the 'perpendicular' transducer position should be used when analyzing echocardiograms for the presence of mitral valve prolapse.

Echocardiography↗
PubMed1975

Changing haemodynamics in patient with papillary muscle dysfunction.

A patient with papillary muscle disease caused by myocardial infarction was studied before and after injection of phenylephrine. The pulmonary wedge pressure was normal at rest. However, pressures and murmur changes, occurring spontaneously and after injection of phenylephrine, suggested that intermittent severe mitral regurgitation contributed significantly to the recurrent episodes of acute left heart failure presented by this patient.

Blood Pressure↗
PubMedDate not supplied

Circulatory effects of diazepam in heart disease.

Diazepam was administered to ten patients with heart disease during diagnostic cardiac catheterization, in order to determine whether or not this drug's circulatory actions could alter results obtained during the procedure. Diazepam produced no change in baroreceptor sensitivity; however, there was a significant rise in heart rate and a significant fall in aortic systolic and left ventricular end-diastolic pressures. Cardiac index was unchanged, whereas stroke volume fell significantly. Systemic vascular resistance and peak left ventricular dp/dt did not change throughout the study. Clinical response in terms of sedation was judged to be satisfactory in eight patients, and no adverse effect on respiration was noted. Diazepam has little effect on basal circulatory and respiratory parameters when changes in these parameters are averaged for our ten patients. However, substantial changes in hemodynamic parameters did occur in several individuals, and such alteration in circulatory function must be considered when this agent is used routinely in patients having diagnostic cardiac catheterization.

Blood Pressure↗
PubMedDate not supplied

Characterisation of synthetic DNA probe detecting potato spindle tuber viroid.

Chemically synthesized DNA fragments complementary to selected regions of the potato spindle tuber viroid (PSTV) genome were cloned into Escherichia coli plasmid pUC9. One of the recombinant plasmids (pIBB4) with a 87 bp insert representing the central region of the PSTV genome (nucleotides 88 to 174) was used after labelling by nick translation for detecting PSTV by dot-blot hybridization. The molecular probe was almost as sensitive as the one carrying the full genomic PSTV copy (pAV401), detecting down to 20 pg of PSTV RNA in 8-15 micrograms of infected tissue. The specificity of the test was high; no signals were created by extracts from healthy plants or plants infected with a variety of common potato viruses. The probe is potentially useful in studies on mixed infections of potatoes with different viruses, and in selection of certified seed material.

Base Sequence↗
PubMedDate not supplied

Digital subtraction myocardial contrast echocardiography: design and application of a new analysis program for myocardial perfusion imaging.

Myocardial contrast echocardiography may provide important physiologic information on myocardial perfusion. Most current analysis programs use manual frame grabbing and selecting of the area of interest. This is time-consuming and not highly reproducible. A system for automatic analysis of myocardial contrast echocardiographic studies was developed and evaluated. The program acquires an electrocardiographically gated sequence of end-diastolic images with a frame grabber in a personal computer. The baseline image is subtracted and the videodensity versus time contrast curve parameters are calculated on-line. Fast color-coded analysis is done automatically with a running square window that covers the entire image. A second mode of contrast analysis allows manual selection of multiple regions of interest. The program was evaluated with contrast echo data from open-chest dogs and two demonstrative patients. This myocardial contrast analytic package is an inexpensive, rapid, flexible, convenient, and reproducible on-line method that facilitates myocardial contrast echocardiographic analysis.

Albumins↗
PubMedDate not supplied

Septal/free wall curvature ratio: a noninvasive index of pulmonary arterial pressure.

The leftward septal shift, a well-recognized feature of pulmonary hypertension, was used to quantify right ventricular pressure in 16 patients with pulmonary hypertension and 11 control patients, all with normal left ventricular function. Pulmonary pressure was calculated from the tricuspid regurgitation jet and left ventricular pressure was taken by arm cuff measurements. Short-axis echocardiographic images were obtained and the midwall curvatures of the septum and the left ventricular free wall were measured for each frame from end diastole to end systole and averaged. The septal/free-wall curvature ratio (CR) was 0.37 +/- 0.19 in the study group compared with 0.79 +/- 0.06 in the control group (p < 0.0001). A tight relationship between the CR and the transseptal/transmural pressure ratio (CR = 0.057 + 0.89 x transseptal/transmural pressure ratio; r = 0.98; p < 0.001) was obtained by linear regression. Given the systolic arterial pressure, the pulmonary systolic pressure is given by: systolic arterial pressure x (1.064-1.12 x CR). Therefore the CR can be used as a noninvasive index that reflects the level of pulmonary pressure in relationship to the systolic arterial pressure.

Blood Pressure↗
PubMedDate not supplied

The effect of minocin on the pericardium.

The purpose of this study was to evaluate in a dog model whether intrapericardial instillation of tetracycline is superior to the effect of drainage alone in causing pericardial adhesions and cavity obliteration. Twelve mongrel dogs were randomly divided into two experimental groups. All dogs received a pericardial drain through a sterile thoracotomy. Group A dogs (n = 6) received minocycline hydrochloride, 20 mg/kg, group B received normal saline. All dogs were sacrificed 1 month later. Echocardiograms performed 1 week postsurgery were normal in all dogs. Macroscopic evaluation disclosed that all group A dogs had over 25% cavity obliteration whereas group B dogs had no adhesions or had obliteration of less than 25% of the cavity area. Microscopic evaluation showed that group A dogs had severe pericardial fibrosis and thickening with slight focal lymphoplasmocytic infiltration. Myocardial damage was not seen. Our results support the clinical use of injecting tetracycline into the pericardium (in addition to drainage) to cause cavity obliteration in patients with persistent pericardial effusion.

Animals↗