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Biomedical subjects

M J Kern

Publications and source records attributed to M J Kern.

At least 217 records · Page 12Linked to original sources
PubMed1992

Initial experience with a new compression device for hemostasis after femoral arterial puncture.

We evaluated a new hemostasis device to maintain focused pressure over the femoral artery puncture site for 2-6 hours in 330 cases after diagnostic catheterization or coronary angioplasty. No patient developed later hematoma or vascular complications. The initial favorable experience suggests that this hemostasis device has advantageous features of stability and site visualization and is a suitable adjunct to current methods of maintaining puncture site pressure after brief manual compression following arterial catheterization.

Cardiac Catheterization↗
PubMed1992

Interpretation of cardiac pathophysiology from pressure waveform analysis: mitral valve gradients: Part I.

The mitral valve gradient is dependent on the precise measurement of left atrial (or pulmonary capillary wedge) and left ventricular pressures. Artifacts involving either pressure measurement will produce inaccuracies which may have clinical significance. Several methods and formulas using both invasive and noninvasive techniques should verify clinical findings and confirm the severity of mitral valve disease prior to definite therapy. The changes in mitral valve gradients after balloon catheter valvuloplasty will be discussed in part II of this hemodynamic rounds.

Blood Flow Velocity↗
PubMed1992

Interpretation of cardiac pathophysiology from pressure waveform analysis: mitral valve gradients: Part II.

Balloon mitral commissurotomy in many patients will be as satisfactory as closed surgical commissurotomy. Data from combined hemodynamic and echocardiographic techniques elegantly elucidate the mechanisms of mitral valve flow and pathophysiology of disturbed pressure relationships between the left atrial and left ventricular chambers, both before and after balloon valvuloplasty. The pulmonary capillary wedge pressure may not be satisfactory to assess the success of gradient reduction after mitral valvuloplasty.

Adult↗
PubMed1992

The usefulness of a tracking catheter in complex coronary angioplasty.

Complex lesion angioplasty, such as chronic total occlusions, coronary vessels with right angle take-offs, tortuous vessels, and tortuous internal mammary artery or saphenous vein grafts is a continuing challenge. The complex problems have been successfully managed with novel guiding catheter shapes and ultralow profile balloons. However, on occasion steerable guidewire placement remains extremely difficult, despite significantly improved means of intracoronary manipulations.

Aged↗
PubMed1992

Intermittent coronary spasm during graded exercise.

We report a patient with Prinzmetal's angina with nearly normal coronary angiogram who not only developed severe myocardial ischemia during exercise, documented both electrocardiographically (ST elevation) and scintigraphically (with thallium-201), but also did so intermittently as the graded exercise progressed. Diagnostic coronary angiography showed spontaneous focal spasm of the proximal left anterior descending coronary artery. This unique response to exercise in a patient with variant angina suggests that factors other than catecholamine stimulation alone are active and rapidly attenuated in some patients. This phenomenon could be overlooked without appropriate electrocardiographic monitoring.

Angina Pectoris, Variant↗
PubMed1992

The effect of ergonovine on coronary vasodilatory reserve in patients with angiographically normal coronary arteries.

Ergonovine produces physiologic coronary artery narrowing in many patients without focal coronary spasm. The effect of ergonovine-induced coronary vasoconstriction on coronary vasodilatory reserve is unknown. Therefore we studied 10 patients with atypical chest pain and angiographically normal coronary arteries. The heart rate and blood pressure were recorded continuously and coronary Doppler flow velocity was measured continuously with a 20 MHz Doppler-tipped catheter. Ergonovine caused diffuse narrowing of the vessels in all patients, with a 12% +/- 5% change in diameter of the left anterior descending coronary artery (p less than 0.001). There was a significant change in systolic (17% +/- 12% change; p less than 0.05) and mean arterial pressure (13% +/- 13% change; p less than 0.05), with no significant change in mean coronary flow velocity with ergonovine. Ergonovine also did not attenuate the maximal hyperemic response with papaverine. Thus despite an increase in myocardial demand and a decrease in caliber of conductance coronary vessels, the coronary autoregulatory flow responses were intact after the administration of ergonovine.

Angina Pectoris, Variant↗
PubMed1992

The effects of ionic and nonionic radiographic contrast media on coronary hyperemia in patients during coronary angiography.

The purpose of this study was to compare the differential effects of ionic, high-osmolar meglumine diatrizoate; ionic, low-osmolar ioxaglate meglumine; and nonionic, low-osmolar iohexol (all radiographic contrast agents) on coronary blood flow velocity and hyperemic responses during diagnostic coronary angiography. Coronary flow velocity and arterial pressure were measured at baseline and during maximal hyperemia after contrast media were randomly injected (4 to 6 ml into left coronary artery) in 22 patients with the use of a Judkins-style 20 MHz Doppler-tipped angiographic catheter. Contrast media-induced hyperemic responses were compared to those induced with intracoronary nitroglycerin (200 micrograms) and papaverine (10 mg). There were no significant differences in systolic, diastolic, or mean arterial pressure measurements among the three contrast agents. The increase in mean coronary flow velocity during hyperemia was 118 +/- 93%, 133 +/- 73%, and 136 +/- 86% for iohexol, ioxaglate meglumine, and diatrizoate, respectively (p = NS among agents vs 264 +/- 109% for papaverine; p less than 0.05 for all). Coronary vasodilatory reserve (calculated as the ratio of hyperemic to basal mean flow velocity) was also similar among agents. It was comparable to the coronary vasodilatory reserve with nitroglycerin (2.1 +/- 1.0 to 2.2 +/- 1.1) and significantly less than that with papaverine (3.3 +/- 2.2, p less than 0.05). These data indicate that the clinical advantages of nonionic or low-osmolar contrast media are not mechanistically related to significant attenuation of the coronary hyperemic response.

Blood Flow Velocity↗
PubMed1992

Effect of viscosity and iodine concentration of nonionic radiographic contrast media on coronary arteriography in patients.

To assess the influence of viscosity and iodine concentration, three matched and standardized left coronary arteriograms were obtained in 20 patients using iopamidol (Isovue-370), ioversol (Optiray-320), and iohexol (Omnipaque-350). The order of contrast media was randomized and the administration of contrast was double-blinded. Quantitative densitometric angiographic evaluation of the coronary angiograms was performed in addition to independent operator qualitative assessment. The injection volume of iopamidol (5.4 +/- 1.0 ml) was slightly but significantly less than that of ioversol and iohexol (5.6 +/- 1.0 ml, 5.7 +/- 1.0 ml, both p less than 0.05). The calculated iodine concentration was also lower for ioversol (1.7 +/- 0.32 gm) than for iopamidol (1.98 +/- 0.35 gm) and iohexhol (1.9 +/- 0.35 gm, both p less than 0.05). There were significantly lower contrast syringe injection pressures for ioversol (6.6 +/- 0.8 atm) than for iopamidol (7.5 +/- 0.9 atm) and iohexol (7.2 +/- 1.1 atm, both p less than 0.05). The quantitative densitometric analysis failed to demonstrate significant differences among the contrast media with respect to image density parameters for any individual agent. All coronary angiograms were deemed of diagnostic quality. The data in this study indicated that although differences in iodine concentration exist among the three agents, operator compensation with more rapid contrast delivery (higher volume) and lower viscosity (lower injection pressure) produced equivalent image opacification during coronary angiography. Given the same incidence of adverse hemodynamic and clinical effects, selection of a low viscosity media theoretically provides an advantage during procedures using small diameter catheters or interventional procedures requiring contrast visualization through reduced catheter lumina.

Contrast Media↗
PubMed1992

Alterations of phasic coronary artery flow velocity in humans during percutaneous coronary angioplasty.

BACKGROUND AND OBJECTIVES: Studies using Doppler catheters to assess blood flow velocity and vasodilator reserve in proximal coronary arteries have failed to demonstrate significant improvement immediately after coronary angioplasty. Measurement of blood flow velocity, flow reserve and phasic diastolic/systolic velocity ratio performed distal to a coronary stenosis may provide important information concerning the physiologic significance of coronary artery stenosis. This study was designed to measure these blood flow velocity variables both proximal and distal to a significant coronary artery stenosis in patients undergoing coronary angioplasty. METHODS: A low profile (0.018-in.) (0.046-cm) Doppler angioplasty guide wire capable of providing spectral flow velocity data was used to measure blood flow velocity, flow reserve and diastolic/systolic velocity ratio both proximal and distal to left anterior descending or left circumflex coronary artery stenosis. These measurements were made in 38 patients undergoing coronary angioplasty and in 12 patients without significant coronary artery disease. RESULTS: Significant improvement in mean time average peak velocity was noted in distal coronary arteries after angioplasty (before 19 +/- 12 cm/s; after 35 +/- 16 cm/s; p less than 0.01). Increases in proximal average peak velocity after angioplasty were less remarkable (before 34 +/- 18 cm/s; after 41 +/- 14 cm/s; p = 0.04). Mean flow reserve remained unchanged after angioplasty both proximal (1.5 +/- 0.5 vs. 1.6 +/- 1; p greater than 0.10) and distal (1.6 +/- 1 vs. 1.5 +/- 0.8; p greater than 0.10) to a coronary stenosis. Before angioplasty, mean diastolic/systolic velocity ratio measured distal to a significant stenosis was decreased compared with that in normal vessels (1.3 +/- 0.5 vs. 1.8 +/- 0.5; p less than 0.01). After angioplasty, distal abnormal phasic velocity patterns generally returned to normal, with a significant increase in mean diastolic/systolic velocity ratio (1.3 +/- 0.5 vs. 1.9 +/- 0.6; p less than 0.01). Phasic velocity patterns and mean diastolic/systolic velocity ratio measured proximal to a coronary stenosis were not statistically different from values in normal vessels (1.8 +/- 0.8 vs. 1.8 +/- 0.5; p greater than 0.10) and did not change significantly after angioplasty (1.8 +/- 0.8 vs. 2.13 +/- 0.9; p greater than 0.10). CONCLUSIONS: Flow velocity measurements may be performed distal to a coronary stenosis with the Doppler guide wire. Phasic velocity measurements made proximal to a coronary stenosis differed from those in the distal coronary artery. Both proximal and distal flow reserve measurements made immediately after angioplasty were of limited utility. Changes in distal flow velocity patterns and diastolic/systolic velocity ratio appeared to be more relevant than the hyperemic response in assessing the immediate physiologic outcome of coronary angioplasty.

Angioplasty, Balloon, Coronary↗
PubMed1992

Smoking is a risk factor for coronary spasm in young women.

BACKGROUND: Risk factors for pure coronary spasm are not known. Clinical observations have pointed to cigarette smoking, a known risk factor for obstructive coronary artery disease. METHODS AND RESULTS: We conducted a case-neighborhood control study of premenopausal women, a population segment with the lowest prevalence of obstructive coronary artery disease. The cases were 21 premenopausal women (age range, 36-41 years) with angiographically proven coronary spasm. All coronary arteriograms were analyzed by two independent experienced cardiologists on two occasions. There were no differences between analyses; all cases had normal baseline coronary angiogram except for two, who had less than 20% coronary luminal stenosis in segments other than the site of the focal vasospasm. All cases had normal hemodynamics at rest, normal left ventricular function, and were in sinus rhythm. Ascertainment of the cases was done by angiographic demonstration of focal coronary spasm spontaneously or by ergonovine provocation. Six cases developed spontaneous coronary spasm before catheter engagement, and in 15, coronary spasm was induced by ergonovine provocation. Each case was asked to name as many as possible female neighborhood acquaintances of similar age and racial background who were willing to answer the same standardized questionnaire. The same standardized questionnaire was completed for each case and each control (n = 63). The standardized questionnaire was designed to obtain information on health characteristics, habits, socioeconomic status, and education. Only cigarette smoking was significantly more prevalent among coronary spasm cases. Cigarette smokers were 13 cases (62%) and 11 controls (17.5%) (p less than 0.001). The odds ratio was 7.7, with a 95% confidence interval of 2.6-23.1. CONCLUSIONS: These findings suggest that there is a very strong association between cigarette smoking and pure coronary spasm in young women.

Adult↗
PubMed1991

Importance of myocardial infarct artery patency on the prevalence of ventricular arrhythmia and late potentials after thrombolysis in acute myocardial infarction.

Sustained infarct artery patency is an important determinant of survival in patients with acute myocardial infarction. We studied 61 patients with acute myocardial infarction who received intravenous recombinant tissue-type plasminogen activator, aspirin or heparin within 6 hours of symptom onset, to determine if infarct artery patency after intravenous thrombolytic therapy influences myocardial electrical stability as measured by the prevalence of spontaneous ventricular ectopy or late potential activity. Infarct artery patency was determined by angiographic evaluation 2.5 +/- 3 days after infarction. Forty-eight patients (79%) had a patent infarct-related artery and 13 (21%) patients had an occluded vessel. The mean number of ventricular premature complexes (VPCs)/hour (p less than 0.01) and the prevalence of late potentials (54 vs 19%; p less than 0.03) were significantly higher in patients with an occluded versus patent-infarct related vessel. Although VPC frequency and late potentials were not influenced by the time to thrombolytic treatment, patients with a patent infarct-related artery had a lower prevalence of late potentials regardless of whether treatment was initiated less than or equal to 2 hours (25% patent vs 50% occluded; p = not significant) or 2 to 6 hours (16% patent vs 55% occluded; p greater than 0.03) after symptom onset. Thus, successful thrombolysis decreases the frequency of ventricular ectopic activity and late potentials in the early postinfarction phase. The reduction in both markers of electrical instability may help explain why the prognosis after successful thrombolysis is improved after acute myocardial infarction.

Aged↗