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Biomedical subjects

M J Kern

Publications and source records attributed to M J Kern.

At least 325 records · Page 18Linked to original sources
PubMed1988

Coronary angioplasty: a therapeutic option for symptomatic patients with two and three vessel coronary disease.

Coronary angioplasty is a widely applied revascularization procedure for patients with multivessel coronary artery disease. However, follow-up in this patient subgroup is relatively limited. From 1983 to 1986, coronary angioplasty was performed in 349 and 121 patients with, respectively, two- and three-vessel coronary disease with a primary success rate of 83 and 88%. The in-hospital mortality rate was 2.8% (13 of 470 patients). Complete revascularization was achieved in 128 patients. Among the 397 patients with a successful outcome, 373 (94%) were followed up greater than or equal to 1 year; 79% were free of death, nonfatal myocardial infarction or the need for coronary bypass grafting, and 82% of patients had symptomatic improvement by at least one angina functional class. A second coronary angioplasty procedure was required in 13% of patients. After a mean follow-up period of 27 months, an increased incidence of coronary bypass grafting was noted in patients with incomplete versus complete revascularization (16 versus 7%, p less than 0.05). Among the 222 patients who had repeat cardiac catheterization performed an average of 7 months after angioplasty, 103 were symptomatic; 50% of the 222 patients had at least one vessel with greater than or equal to 50% restenosis and 14% of patients had multiple restenoses. In conclusion, coronary angioplasty can be performed with a high initial success rate and marked symptomatic improvement in patients with multivessel coronary disease. However, in this group's experience, the majority of patients selected for coronary angioplasty with multivessel coronary disease will have incomplete revascularization that can be predicted in the majority of patients before the procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

The changing mortality of myocardial revascularization: coronary artery bypass and angioplasty.

The risk factors and outcome for the first 150 consecutive patients undergoing coronary artery bypass grafting (CABG) in 1985 (CABG '85) were compared with those of the first 150 patients undergoing CABG in 1975 (CABG '75) and those of the first 150 patients to have percutaneous transluminal coronary angioplasty (PTCA) in 1985 (PTCA '85). The CABG '85 patients had a significantly higher (p less than 0.05) incidence of known operative risk factors including advanced age, female sex, severity of angina, history of recent infarction, triple-vessel disease, left ventricular dysfunction, and emergency operation than the CABG '75 cohort. The clinical profile of the PTCA '85 patients closely resembled the low-risk profile found in the CABG '75 patients. Overall mortality following CABG more than doubled during the decade studied (3% versus 7%, p = 0.07). This study suggests that the increased mortality associated with CABG in 1985 is due in part to the inclusion of more high-risk patients in the surgical population. In addition, the application of PTCA removes low-risk patients from the surgical candidate pool and adds more patients requiring emergency operations, thereby further contributing to the overall decline in the clinical status of patients referred for operation.

Age Factors↗
PubMed1987

Restenosis after multilesion percutaneous transluminal coronary angioplasty.

Experience and new technical advances have resulted in an increasing number of patients with multivessel coronary disease who can be considered for percutaneous transluminal coronary angioplasty (PTCA). In selected patients with multivessel coronary disease, PTCA is a safe and effective procedure for the immediate relief of anginal symptoms. However, many questions remain regarding the long-term therapeutic benefit of the procedure. Few data are available on the incidence and clinical significance of restenosis after multilesion PTCA. Clearly, there is the potential for a higher rate of restenosis in patients who undergo dilatation of more than 1 lesion. Determination of restenosis rates after multilesion PTCA is important in the definition of expanded indications for this procedure. Because of the variations in definitions of restenosis and in patient selection factors, reported recurrence rates after multilesion PTCA are not easily compared between patient series. After multilesion dilatation the risk of developing at least 1 recurrent lesion ranges from 26% to 53% and appears to be greater than that reported for single lesion PTCA. Multilesion restenosis occurs in 7% to 21% of patients who undergo multilesion PTCA and is frequently observed in patients with recurrent symptoms. "Silent" multilesion restenosis (i.e., multiple lesion restenosis without symptoms) is rare. A higher risk of restenosis at one of several dilatation sites in a patient with extensive coronary disease should not be a deterrent in recommending multilesion PTCA to selected patients with multivessel coronary disease because the procedure provides important symptomatic relief to most. Further, recurrent narrowings are usually amenable to a second dilatation attempt if clinically indicated.

Angioplasty, Balloon↗
PubMed1987

Coronary artery bypass surgery in patients aged 80 years or older.

Between August 1980 and January 1986, 23 patients aged 80 years or older underwent coronary artery bypass grafting (CABG) operations. These patients had a higher incidence of severe left main coronary artery narrowing (p less than 0.0001), 3-vessel coronary artery disease (p less than 0.05) and moderate to severe left ventricular dysfunction (p less than 0.05) than patients in the Coronary Artery Surgery Study registry older than 65 years. Of 14 patients undergoing elective simple CABG procedures, none died; of 19 elective cases overall, 2 patients died (11%). Three of 4 patients undergoing emergency procedures (75%) and 4 of 6 patients (67%) requiring intraaortic balloon counterpulsation died. Significant complications occurred in 9 of 18 survivors (50%). All operative survivors improved at least 1 New York Heart Association class, with a mean classification improvement of 3.7 to 1.6 (p less than 0.0001); 13 of 16 long-term survivors were in class I or II. Actuarial survival at 1 and 2 years is 94% and 82%, respectively. CABG can be performed electively in octogenarian patients with increased but acceptable mortality and morbidity risks. Functional improvement and long-term survival are excellent.

Aged↗
PubMed1987

Attenuation of nitroglycerin-induced coronary hyperemic blood flow in patients with left anterior descending coronary collaterals.

Although intracoronary nitroglycerin (NTG) is frequently administered to patients having occluded coronary arteries undergoing invasive procedures such as percutaneous transluminal coronary angioplasty or thrombolysis, the extent of NTG-induced augmentation of myocardial blood flow in patients with collaterally filled occluded arteries is incompletely understood. To examine NTG-induced increases in coronary blood flow in patients with occluded left anterior descending coronary arteries (LAD), coronary and systemic hemodynamics were measured during bolus administration of NTG into the left coronary artery in 10 patients with normal LAD (Group 1), 11 patients with greater than 70% and less than 100% narrowing of the LAD (Group 2), and 10 patients who had total occlusion of the LAD with angiographic collateral filling and anterior ventricular wall motion abnormalities (Group 3). NTG increased anterior regional great vein flow (thermodilution) from 72 +/- 19 to 140 +/- 60 ml/min (p less than 0.05), 67 +/- 27 to 108 +/- 66 ml/min (p less than 0.05), and 59 +/- 27 to 74 +/- 36 ml/min (p = NS vs. control, p less than 0.05 vs. peak flow for Group 1) with relative increases from control of 91 +/- 41%, 56 +/- 34%, and 25 +/- 22% for the three groups, respectively. The percent change for Group 3 was significantly lower than both Groups 1 (p less than 0.01) and 2 (p less than 0.05). These data indicate that myocardial hyperemic blood flow responses to intracoronary NTG are markedly attenuated in patients with occluded but collaterally supplied vessels. During invasive procedures in these patients, although significantly attenuated, intracoronary NTG may potentially provide a beneficial effect by augmenting blood flow through collaterals or in adjacent regions.

Coronary Angiography↗
PubMed1987

Multilesion coronary angioplasty: clinical and angiographic follow-up.

Determination of the restenosis rate after multilesion percutaneous transluminal coronary angioplasty is an important consideration in defining expanded indications for the procedure. Of 209 patients who underwent successful multilesion coronary angioplasty, 55 symptomatic and 74 asymptomatic patients were restudied an average of 7 +/- 4 months after dilation. The restenosis rate was 82% (45 of 55) in the symptomatic patients and 30% (22 of 74) in the asymptomatic patients (p less than 0.001). Only 4% of the asymptomatic patients had restenosis at more than one dilation site. When only patients who developed a restenosis were considered, the restenosis occurred at more than one dilation site in 47% (21 of 45) of the symptomatic group versus 14% (3 of 22) of the asymptomatic group (p less than 0.05). When all recurrent stenoses were examined, the severity of the luminal narrowing was greater than or equal to 70% in 64% (45 of 70) of the stenotic lesions in the symptomatic patients versus 31% (8 of 26) of the stenotic lesions in the asymptomatic patients (p less than 0.05). Proximal left anterior descending coronary artery disease, increased length of the stenotic narrowing, male gender and diabetes were associated with an increased incidence of restenosis by multivariate analysis. Patient-related variables were not predictive of multilesion restenosis. In conclusion, the majority of patients are clinically improved after multilesion coronary angioplasty. Recurrent symptoms after multilesion coronary angioplasty are frequently associated with multilesion restenosis and a more severe degree of restenotic narrowing. Restenosis at more than one dilation site is uncommon in the asymptomatic patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Development and experimental application of contact probe catheter for laser angioplasty.

A sapphire contact probe laser catheter was developed to increase the dimensions of tunnels created by laser angioplasty. The device consisted of a round sapphire probe (2.2 mm diameter) attached to an 8F catheter into which a 0.2 mm optical fiber was inserted with a tip maintained at 3 mm from the sapphire. The fiber was connected to a continuous wave neodymium yttrium aluminum garnet (Nd-YAG) laser. A saline perfusate was circulated through the catheter during laser emissions to prevent excessive heating of the fiber tip. The system was used in vitro on 16 sections of atherosclerotic calcified human cadaver aortic walls, using diluted blood as a medium, at powers ranging from 10 to 40 W and exposure times from 1 to 4 seconds. Six craters were created at each energy level. The system was also used on six human cadaver, agar-embedded, obstructed iliac and femoral arteries, using 40 W and 2 second laser emissions. Dimensions of probe-created craters were compared with those obtained using bare fibers. The shape of the probe craters was that of a truncated cone with the entry hole wider than the exit, as opposed to the cylindrical shape created with unmodified bare fibers. At 120 J (seconds X watts), areas of entry and exit probe-formed holes were greater than those created with the bare fibers (6.7 +/- 0.5 and 3.4 +/- 0.6 versus 0.2 +/- 0.01 mm2, respectively, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗
PubMed1987

Efficiency and safety of optically modified fiber tips for laser angioplasty.

To evaluate the safety and efficiency of optically modified fiber tips, craters were created in human cadaver atherosclerotic arterial walls using sapphire contact probes and lensed fibers connected to a continuous wave neodymium yttrium aluminum garnet (Nd-YAG) laser. Laser energy was emitted at a constant level of 50 J. The sapphire contact probe catheter consisted of a round 2.2 mm diameter synthetic sapphire attached to an 8F catheter into which a 0.2 mm diameter optical fiber was inserted with the distal tip maintained at 3 mm from the sapphire. The lensed fiber catheter consisted of a 0.2 mm optical fiber at the end of which a 1 mm diameter lens was made. The fiber was inserted into a 5F low profile balloon catheter with the lens maintained 3 mm beyond the catheter tip. During laser emissions the catheter tips were maintained in a stationary position in contact with tissue targets immersed in blood at an angle of 90 degrees. The diameter of holes at the entry and exit of craters, the depth of craters and thermal injury to adjacent tissue (rim of carbonization and vacuolization) were measured with microscopy. The volume of tissue removed was derived from these values. Controlled effect index was determined as the ratio of diameter of holes and the extent of thermal injury. Efficiency was determined as the ratio of volume of tissue removed and the energy required to vaporize tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗
PubMed1987

Prolonged myocardial ischemia after intravenous dipyridamole thallium imaging.

Intravenous dipyridamole thallium imaging is reported to be a safe test with minimal side effects. It has been proposed by some that the test simply dilates the coronary vessels without actually producing myocardial ischemia. In this report, we describe a patient who, following intravenous dipyridamole thallium imaging, developed severe myocardial ischemia which persisted for 90 minutes, requiring emergency coronary angioplasty to alleviate the ischemic insult. Sequential electrocardiograms and cardiac isoenzyme levels following coronary angioplasty were within normal limits. Thus, severe myocardial ischemia following intravenous dipyridamole testing can occur and emphasizes the importance of careful monitoring of these patients, particularly when the pretest risk of coronary disease is high.

Cardiomyopathies↗
PubMed1986

Alterations in regional myocardial blood flow after nitroprusside and nitroglycerin in patients with and without significant coronary artery disease.

To evaluate vasodilator-induced redistribution of regional myocardial blood flow, intravenous sodium nitroprusside and nitroglycerin were administered in doses producing matched reductions (15%) in mean arterial pressure at constant heart rate. Anterior left ventricular great cardiac vein blood flow (thermodilution) was measured in 14 patients without angiographic anterior collateral supply. Global coronary sinus blood flow remained constant with both nitroprusside and nitroglycerin administration, despite significant reductions in mean arterial pressure. However, nitroglycerin reduced great vein flow by 25 +/- 17% and nitroprusside by 10 +/- 16% (p less than 0.01). Subgroup analysis indicated that the nitroglycerin-nitroprusside regional blood flow differences were more pronounced in patients without significant left anterior descending coronary artery narrowing. Neither vasodilator produced significant differences in arterial-coronary sinus oxygen or lactate contents, calculated myocardial oxygen consumption, left ventricular dP/dt, or electrocardiographic or clinical signs of myocardial ischemia. Despite qualitatively similar hemodynamic effects, comparisons of vasodilator-induced relative reductions in normally supplied anterior left ventricular regional coronary blood flow suggest a mechanism of the reported beneficial effects of nitroglycerin on potentially ischemic myocardial regions.

Adult↗