Should all patients undergoing cardiac catheterization or percutaneous transluminal coronary angioplasty receive oxygen?

BACKGROUND: Supplemental oxygen is routinely administered to patients with acute coronary syndromes. The risk of significant morbidity during cardiac catheterization or coronary angioplasty has been well described; however, to our knowledge, the need for routine oxygen supplementation in these patients has not been investigated. METHODS: In phase 1, we prospectively studied 142 patients undergoing diagnostic cardiac catheterization (n = 94) or percutaneous transluminal coronary angioplasty (PTCA) (n = 48) to determine the incidence of procedure-related hypoxemia (pulse oximetry derived oxygen saturation [SpO2] < 90 percent of > 1 min duration) while breathing room air (RA). In phase 2, 134 patients undergoing diagnostic cardiac catheterization (n = 78) or PTCA (n = 56) were randomly allocated to breathe either RA or supplemental oxygen (O2, 6 L/min by nasal cannula) to determine the effect of oxygen administration on procedure-related hypoxemia. Oximetry results were compared with pertinent clinical and procedural data that might predispose patients to develop hypoxemia. RESULTS: Phase 1--Moderate to severe hypoxemia occurred in 36 percent (34/94) of patients undergoing diagnostic catheterization and in 56 percent (27/48) of patients undergoing PTCA. In the diagnostic catheterization group, there were a total of 25 episodes of moderate hypoxemia (SpO2 85 to 89 percent) lasting 4.0 +/- 4.3 min and 11 episodes of severe hypoxemia (SpO2 < 85 percent) of greater duration, 11.7 +/- 7.5 min (p < 0.008). In the PTCA group, there were 24 episodes of moderate hypoxemia and six episodes of severe hypoxemia lasting 4.8 +/- 4.3 min and 8.2 +/- 3.8 min, respectively. A history of chronic lung disease was associated with hypoxemia (p < 0.05) in the diagnostic group. In addition, 11 patients undergoing diagnostic catheterization who had baseline SpO2 < 95 percent all developed hypoxemia during the procedure. In this subset of patients, there was a higher incidence of cigarette smoking (p = 0.02), chronic lung disease (p = 0.04), higher left ventricular diastolic pressure (p = 0.02), and lower ejection fraction (p = 0.002) when compared with the 83 remaining patients undergoing diagnostic catheterization with a baseline SpO2 > 95 percent. Phase 2--Oxygen therapy was associated with a reduction in the incidence of hypoxemia from 42 percent to 5 percent (RA vs O2, p < 0.001) in the diagnostic catheterization group and 39 percent to 11 percent (RA vs O2, p < 0.03) in the PTCA group. CONCLUSIONS: Significant hypoxemia is a common finding among patients undergoing cardiac catheterization or angioplasty despite the absence of predictive risk factors. Severe and prolonged hypoxemic episodes occurred in 10 percent (14/142, phase 1) of patients breathing room air. Patients undergoing diagnostic catheterization with history of chronic lung disease or a baseline SpO2 < 95 percent are at high risk to develop moderate-severe hypoxemia. Oxygen therapy significantly reduced the incidence and severity of procedure-induced hypoxemia in both groups. Our data support the use of both pulse oximetry and oxygen supplementation in patients undergoing cardiac catheterization and PTCA.

Relationship between location of chest pain and site of coronary artery occlusion.

Chest pain characteristics and site of coronary artery occlusion were evaluated in 148 patients having single-vessel coronary angioplasty and in 95 patients having double-vessel angioplasty. The locations of chest pain included substernal and left precordium, right precordium and epigastric. The possible sites of pain radiation were limited to neck/jaw, left arm, right arm, and interscapular. The patient described whether or not the pain was typical of previous angina, and the presence of ST segment deviation was noted to be certain that ischemia was present. The analysis showed that the occluded artery could not be reliably identified. However, it was possible to say which artery was most likely not diseased. Patients presenting with substernal or left chest pain with radiation to the left arm had a less than 10% chance of having right coronary artery disease. A patient presenting with epigastric pain radiating to the neck or jaw had a less than 13% chance of having left anterior descending disease. It is concluded that in patients with single- and double-vessel coronary disease, there is some relationship between chest pain pattern and disease location.

Spontaneous coronary dissection treated with directional coronary atherectomy.

We report a case of spontaneous coronary dissection occurring in a middle aged male which was treated with thrombolytic therapy and directional coronary atherectomy. This technique provides a new option for treating this entity in the cardiac catheterization laboratory.

Intracoronary ST-T alternans during coronary balloon angioplasty.

To evaluate the presence and clinical significance of electrical alternans during PTCA, intracoronary electrocardiography (ic-ECG) was performed in 65 consecutive lesions. ST-T alternans, defined as a beat-to-beat difference in the ST elevation > or = 1 mm, was present in five lesions (7.7%), all in the proximal left anterior descending (LAD) coronary artery. The phenomenon was seen only after 130 sec (mean 174 +/- 57) of balloon inflation. Only two of the five showed ST-T alternans simultaneously on both surface and ic-ECG. One of five patients had premature ventricular contractions following ST-T alternans. Three of these five lesions required a second balloon inflation with duration of > or = 300 sec; there was no ST-T alternans on the second inflation in any of these lesions. We conclude: (1) the detection of ST-T alternans during PTCA is enhanced by use of ic-ECG, (2) electrical alternans during PTCA was seen only in proximal LAD lesions, implicating a large amount of ischemic myocardium as a requisite for the phenomenon, (3) electrical alternans is not immediate, requiring a certain duration of balloon occlusion and hence ischemia to occur, and (4) the absence of ST-T alternans during second balloon inflations suggests ischemic preconditioning may abolish this phenomenon.