Biomedical subjects

C D Pierce

Publications and source records attributed to C D Pierce.

5 recordsLinked to original sources

PubMed1992

Acute post-MI pericarditis.

The diagnosis of acute pericarditis may be difficult to establish in patients with recent transmural infarcts as the symptomatology frequently mimics the clinical presentation associated with recurrent ischemia. A careful assessment of the postmyocardial infarction patient may reveal the clinical and electrocardiographic features associated with developing pericarditis. Prompt and accurate recognition of this complication is critical in order to institute definitive therapy, minimize the risk of hemodynamic compromise, and provide psychological support.

Acute Disease↗

PubMed1989

Transcutaneous cardiac pacing: expanding clinical applications.

Transcutaneous cardiac pacing is an exciting alternative to invasive endocardial pacing methods for the treatment of hemodynamically significant bradyarrhythmias. Prompt institution of a pacing support system is crucial for improving outcomes in this patient population. Recent advances in technology and microcircuitry have eliminated the problems of painful, musculoskeletal stimulation and excessive distortion of the ECG signal associated with earlier devices. The ease of application and simplicity of operation associated with this technique make it ideally suitable for employment in the emergent situation, especially in the prehospital setting. The noninvasive nature of this technique is particularly beneficial for patients receiving thrombolytic therapy who are at risk for developing reperfusion dysrhythmias. Prophylactic use of transcutaneous pacemakers in a variety of clinical situations, such as atrioventricular blocks, may eliminate the need for transvenous electrode insertion and its related complications. A transcutaneous pacing system with the capability of functioning in the demand mode should be readily available in emergency rooms, intensive care units, and telemetry floors. Although unlikely to replace transvenous methods, the growing popularity of this technique has many implications for the nurse in the critical care setting.

Cardiac Pacing, Artificial↗

PubMed1982

Noninvasive detection and localization of coronary stenoses in patients: comparison of resting dipyridamole and exercise thallium-201 myocardial perfusion imaging.

Two noninvasive tests to detect and localize coronary stenoses were compared in a fully blinded protocol. Thallium201 myocardial perfusion imaging (MPI) following maximal treadmill exercise and pharmacologic coronary vasodilation with intravenous dipyridamole (DP) was performed in 33 patients. Thallium201 imaging defects in six myocardial perfusion regions were correlated with stenoses in their respective vascular distributions. Disease severity was determined with coronary arteriograms using a computer-assisted method. 198 myocardial regions were evaluated; 101 were supplied by at least one major artery with a greater than or equal to 50% stenosis (luminal diameter narrowing). The sensitivity and specificity for detecting a greater than or equal to 50% stenosis were 85% and 64% (p less than 0.005), respectively, for DP and 84% and 68% (p less than 0.005) for exercise-thallium201 imaging. A particular combination of anterior and septal imaging defects was useful in detecting left anterior descending artery stenoses proximal to its first septal branch. DP administration was safe in this group of patients; however, 42% experienced transient chest pain. Although the overall sensitivity and specificity of the two methods were not significantly different, DP-MPI appeared more sensitive than exercise-MPI (70% vs 52%, p less than 0.01) in detecting coronary stenoses in the 40% to 60% range. DP-thallium201 MPI provides a useful alternative test for potential coronary disease patients unable to perform maximal exercise.

Adult↗

PubMed1981

Intravenous dipyridamole combined with isometric handgrip for near maximal acute increase in coronary flow in patients with coronary artery disease.

Twenty-four patients with coronary artery disease were studied during cardiac catheterization to determine the effects of sustained isometric handgrip exercise and intravenous dipyridamole and their combination on coronary and systemic hemodynamics and measured coronary luminal caliber. During 4 to 5 minutes of 25 percent maximal handgrip, blood pressure and heart rate increased 24 and 19 percent, respectively, coronary sinus flow increased to 1.7 x baseline value, and epicardial coronary arteries constricted to increase predicted flow resistance by 40 percent in 36 diseased arterial segments. After a 4 minute intravenous infusion of dipyridamole (0.56 mg/kg body weight), systemic pressure decreased 8 percent, heart rate increased 23 percent, coronary sinus flow increased to 2.4 x baseline value and coronary luminal caliber was unchanged. During isometric handgrip initiated 6 minutes after the infusion of dipyridamole, systemic pressure and heart rate increased to 14 and 31 percent, respectively, above control values, coronary sinus flow increased to 3.3 x baseline value (3.8 x baseline value in patients with normal anterior perfusion) and stenotic flow resistance increased by 36 percent. The response of coronary flow to the combined stresses was 68 percent greater than the response to dipyridamole alone (p less than 0.02); these flow levels exceed values previously reported for the human coronary circulation. Aminophylline plus nitroglycerin appears to assure patient safety.

Acute Disease↗

PubMed1981

The mechanisms of nitroglycerin action: stenosis vasodilatation as a major component of the drug response.

The effect of sublingual or intracoronary nitroglycerin (NTG) on luminal caliber in normal and diseased portions of epicardial coronary arteries was determined in 85 lesions from 57 typical patients with ischemic heart disease. Measurements were made from coronary angiograms, using a computer-assisted method and a carefully blinded protocol for analysis of the pre- and post- NTG angiograms. Luminal area in the "normal" portion of the diseased segment and at its maximum constriction and an estimate of flow resistance in the stenosis were computed. Luminal area increased 1.27 mm2 (p less than 0.001) in the "normal" regions, an average increase of 18% over the control area. Dilation with NTG depended strongly on vessel size; area increased 35% in normal vessels of 1.6-2.3 mm luminal diameter and only 9% in vessels 4.0-5.0 mm in diameter. Lesions were grouped into four levels of severity by percent stenosis. Minimum luminal area increased 0.35 mm2 (p less than 0.01) at the narrowest point in moderate lesions, a 22% area increase, and 0.14 mm2 (p less than 0.001) in severe lesions, a 36% area increase. Stenosis dilation resulted in an average 25% reduction (p less than 0.01) in estimated stenosis flow resistance in moderate lesions and a 38% reduction (p less than 0.001) in severe lesions. A statistically significant resistance reduction of greater than 20% occurred in 15 to 20 severe stenoses; only two of 20 showed no measurable dilation. We reviewed recent literature on hemodynamic responses to NTG and determined that changes of this magnitude are among the largest reported. We conclude that vasodilation of epicardial coronary stenosis is usually a major component of the beneficial response to NTG. We support that conclusion by demonstrating a striking improvement in ischemic left ventricular compliance abnormalities after low-dose intracoronary NTG.

Constriction, Pathologic↗