Biomedical subjects

K C Stajduhar

Publications and source records attributed to K C Stajduhar.

5 recordsLinked to original sources

PubMed1996

Optimal electrode position for transvenous defibrillation: a prospective randomized study.

OBJECTIVES: This study was performed to determine the optimal position for the proximal electrode in a two-electrode transvenous defibrillation system. BACKGROUND: Minimizing the energy required to defibrillate the heart has several potential advantages. Despite the increased use of two-electrode transvenous defibrillation systems, the optimal position for the proximal electrode has not been systematically evaluated. METHODS: Defibrillation thresholds were determined twice in random sequence in 16 patients undergoing implantation of a two-lead transvenous defibrillation system; once with the proximal electrode at the right atrial-superior vena cava junction (superior vena cava position) and once with the proximal electrode in the left subclavian-innominate vein (innominate vein position). RESULTS: The mean (+/- SD) defibrillation threshold with the proximal electrode in the innominate vein position was significantly lower than with the electrode in the superior vena cava position (13.4 +/- 5.7 J vs. 16.3 +/- 6.6 J, p = 0.04). Defibrillation threshold with the proximal electrode in the innominate vein position was lower or equal to that achieved in the superior vena cava position in 75% of patients. In patients with normal heart size (cardiothoracic ratio < or = 0.55), the improvement in defibrillation threshold with the proximal electrode in the innominate vein position was more significant than in patients with an enlarged heart (innominate vein 13.0 +/- 6.5 J vs. superior vena cava 17.9 +/- 5.1 J, p < 0.01). In patients with an enlarged heart, no difference between the two sites was observed (innominate vein 13.9 +/- 4.5 J vs. superior vena cava 13.6 +/- 8.3 J, p = NS). CONCLUSIONS: During implantation of a two-lead transvenous defibrillation system, positioning the proximal defibrillation electrode in the subclavian-innominate vein will lower defibrillation energy requirements in the majority of patients.

Aged↗

PubMed1993

Transcoronary cardiac pacing during myocardial ischemia.

Severe bradyarrhythmias are a rare but potentially life threatening complication of percutaneous transluminal coronary angioplasty (PTCA). Previous work has outlined a technique for coronary pacing using the angioplasty guidewire. To examine the effectiveness of this technique during severe ischemia, seven swine underwent placement of an unmodified 0.014 inch angioplasty guidewire and 3.0 mm balloon catheter in the left anterior descending (LAD) artery. Baseline pacing thresholds were obtained. Pacing was begun at twice diastolic threshold and ischemia was produced by balloon inflation. Repeat capture thresholds were obtained after 1 and 8 minutes of ischemia. Transcoronary pacing was successfully performed in all seven animals and was continued for a mean of 13.8 +/- 1.5 minutes. The baseline capture threshold was 4.0 +/- 0.5 mA. The mean capture threshold was 3.3 +/- 0.3 mA and 4.5 +/- 0.9 mA at 1 and 8 minutes of ischemia, respectively. We conclude that transcoronary pacing using the angioplasty guidewire can be successfully performed during myocardial ischemia and may serve as a reliable backup system during interventional procedures complicated by bradyarrhythmias.

Angioplasty, Balloon, Coronary↗

PubMed1993

Coronary arterial ectasia: increased prevalence in patients with abdominal aortic aneurysm as compared to occlusive atherosclerotic peripheral vascular disease.

Coronary artery ectasia (CAE) is the saccular or fusiform dilatation of a coronary artery. CAE is found in 1.2% to 4.9% of patients at autopsy or during angiographic studies, with a similar prevalence of CAE found in patients with atherosclerotic peripheral vascular disease (PVD). Abdominal aortic aneurysm (AAA) and CAE are similar in pathogenesis and histology. To determine whether CAE occurs more frequently in patients with AAA than in occlusive forms of atherosclerotic PVD, a review of coronary angiograms was performed in patients who underwent cardiac catheterization and vascular reconstruction for AAA or occlusive atherosclerotic PVD of the lower extremities. Of 72 patients with AAA, 15 had CAE (20.8%) compared with only 2 of 69 patients with atherosclerotic PVD (2.9%) (p < 0.003). CAE was predominantly discrete, located in the left coronary system, and associated with significant coronary atherosclerosis. CAE may be more prevalent in patients with AAA resulting from a similar pathogenetic process.

Aged↗

PubMed1993

Right upper lobe pulmonary edema caused by acute mitral regurgitation. Diagnosis by transesophageal echocardiography.

Unilateral pulmonary edema is a distinctly unusual clinical entity, often misdiagnosed initially as one of the more common causes of focal lung disease. Predominantly lobar pulmonary edema is rarer still. We report a case of right upper lobe pulmonary edema caused by the acute onset of severe mitral regurgitation. In addition, we briefly review the other causes of unilateral pulmonary edema, focusing on the cases that have been reported in association with heart failure and valvular heart disease. The majority of cases of right upper lobe pulmonary edema have been associated with mitral regurgitation. In addition to confirming the presence of mitral regurgitation, transesophageal echocardiography proved useful in delineating the mechanism for edema formation. It detected differential gradients between the right and left pulmonary venous systems and documented the direction of the regurgitant flow.

Acute Disease↗

PubMed1992

Oxygen consumption and ventilation during normal labor.

Oxygen consumption (VO2) and minute ventilation (VE) were measured breath-by-breath for 10 min periods in the third trimester of pregnancy in 16 healthy women. These measurements were repeated during the first stage of labor in eight of the women. The 10-min mean VO2 was 3.56 ml/kg/min (+/- 0.82 SD) at term and 4.28 ml/kg/min (+/- 0.93) during labor, for an average increase of 23 percent (+/- 28 percent, p = 0.04) from third trimester to labor. The mean VE was 0.15 L/kg/min (+/- 0.03) at term and increased significantly (p = 0.05) to 0.24 L/kg/min (+/- 0.11) during labor for an average increase in VE of 65 percent (+/- 78 percent). Peak VO2 and VE occurred during contractions with five-breath average peak VO2 being 86 percent (+/- 53%) above the 10-min mean value at term and VE increasing 167 percent (+/- 154 percent) from third trimester to peak values during labor. These data may be useful in identifying patients at risk for developing respiratory insufficiency during labor. We propose an algorithm for approaching the obstetric patient with respiratory disease.

Adolescent↗