Decision analysis in clinical cardiology: when is coronary angiography required in aortic stenosis?

Decision analysis offers a reproducible, explicit approach to complex clinical decisions. It consists of developing a model, typically a decision tree, that separates choices from chances and that specifies and assigns relative values to outcomes. Sensitivity analysis allows exploration of alternative assumptions. Cost-effectiveness analysis shows the relation between dollars spent and improved health outcomes achieved. In a tutorial format, this approach is applied to the decision whether to perform coronary angiography in a patient who requires aortic valve replacement for critical aortic stenosis.

Prophylactic use of the intra-aortic balloon pump in high-risk cardiac patients undergoing noncardiac surgery: a decision analytic view.

OBJECTIVE: As the indications for the intra-aortic balloon pump (IABP) continue to evolve, a potential new use may be the prophylactic preoperative insertion of the IABP in the high-risk cardiac patient undergoing noncardiac surgery. Our objective is to present a general approach to the high-risk cardiac patient who may benefit from the prophylactic insertion of the IABP. DESIGN: Case reports and a decision analysis. METHODS: A decision model was constructed that weighs the risk of life-threatening postoperative complications against the risk of vascular complications, including surgery and possible amputation, from IABP insertion. RESULTS AND CONCLUSIONS: A review of the literature identified 10 patients who underwent IABP placement prior to noncardiac surgery. These patients, along with our three cases, define a population of patients for whom the prophylactic IABP may be useful. This population includes patients with coronary artery disease (CAD) for whom bypass grafting is not an option due to: (1) inoperable CAD; (2) a severe coexisting disease process (such as a malignancy); or (3) the emergent nature of the noncardiac procedure. The decision analysis suggests that patients whose preoperative assessment places them at very high risk for postoperative complications (Goldman class IV or Detsky class III undergoing major surgery) may benefit the most from prophylactic placement of an IABP prior to noncardiac surgery.

Salivary stimulation mimics esophageal exposure to refluxed duodenal contents.

It has been suggested that shifts in gastric and esophageal pH can be used to estimate the reflux of injurious alkaline material, particularly bile, into the esophagus. We sought to evaluate the contribution of swallowed saliva to alkalinization of both the stomach and esophagus in 10 normal volunteers, by performing combined gastric and esophageal pH monitoring before, during, and after salivary stimulation. The intraesophageal pH universally increased during salivary stimulation, whereas the intragastric pH was noted to increase in six of 10 subjects. In four of these six, the pattern of simultaneous increases in esophageal and gastric pH mimicked and could be mistaken for episodes of "alkaline reflux." We conclude that the diagnosis of reflux of duodenal contents into the esophagus by pH monitoring may be compromised by false-positive results related to swallowed saliva.

Acute cardiac ischemia in patients with syncope: importance of the initial electrocardiogram.

OBJECTIVE: To determine the prevalence of acute cardiac ischemia in emergency department (ED) syncope patients without chest pain and to determine which of these patients are at high risk for acute cardiac ischemia. DESIGN: Data were collected prospectively during a study of ED triage of patients who had had possible acute cardiac ischemia. Supplemental retrospective review of records was performed to differentiate syncope from dizziness. SETTING: Six hospital EDs in New England (two primary teaching hospitals in urban locations, two medical-school-affiliated teaching hospitals, and two nonteaching hospitals in rural settings). PATIENTS: 5,762 patients had presented to the ED with chief complaints consistent with acute cardiac ischemia, including chest pain, shortness of breath, dizziness, and syncope. The study sample consisted of 251 patients who had had syncope and no chest pain. RESULTS: The prevalence of acute cardiac ischemia among the syncope patients was 7% (18 of the 251 patients). Univariate analysis revealed the following to have significant association with acute cardiac ischemia: ischemic abnormalities on the electrocardiogram (ECG) obtained in the ED (p less than 0.001), arm or shoulder pain on presentation (p less than 0.05), rales (p less than 0.1), and prior history of exercise-induced angina (p less than 0.05) or myocardial infarction (p less than 0.1). All 18 patients with acute cardiac ischemia had ischemic abnormalities (pathologic Q waves, ST-segment elevation or depression, or T-wave abnormalities) on their presenting ECGs. CONCLUSION: For syncope patients who have no chest pain or ischemic abnormality on the presenting ECG in the ED, acute ischemia appears to be unlikely. Admission to the cardiac care unit for these patients for possible myocardial ischemia is probably unnecessary. However, patients who have syncope and ischemic abnormalities on the ECG are at risk for acute cardiac ischemia, even in the absence of chest pain. Hospital admission to rule out myocardial infarction for these patients is prudent.

Effect of head position on the dynamics of the upper esophageal sphincter and pharynx.

Due to limitations in available technology it has been difficult to obtain data on upper esophageal sphincter (UES) and pharyngeal (P) function under varying physiologic conditions. We used a manometry system with solid-state intraluminal transducers, including a circumferential sphincter transducer, and computer analysis to measure pressure changes in UES and P during wet (5 ml H2O) swallows as the head was moved through a 75 degree arc in nine normal volunteers. UES residual pressure increased markedly and duration of UES relaxation decreased with increasing head extension. Similar decreases were also seen with time between P peak and both UES nadir and UES end. There were no changes in either pharyngeal peak pressures or the duration of the pharyngeal contraction. Head extension produces major changes in UES relaxation and UES/P coordination. These effects may be clinically important when feeding neurologically impaired patients.

Effect of percutaneous balloon valvuloplasty on pulmonary hypertension in mitral stenosis.

Percutaneous mitral balloon valvuloplasty (PMBV) has been useful in decreasing mitral valve obstruction in mitral stenosis; however, the long-term effects of valvuloplasty on pulmonary artery pressure have not been extensively studied. Thirty-three patients underwent PMBV in our institution between January 1988 and December 1991. There were significant reductions in peak (19 +/- 1 to 12 +/- 1 mm Hg) and mean (10 +/- 0.7 to 6 +/- 0.4 mm Hg) mitral valve gradients estimated by Doppler techniques immediately after PMBV. The mitral valve area, as assessed by the pressure half-time method, increased from 1.06 +/- 0.05 to 1.98 +/- 0.08 cm2 (p < 0.001) after the procedure and remained significantly greater (1.68 +/- 0.11 cm2) at 17 +/- 2 months. Right ventricular systolic pressure (RVSP) was estimated in patients with tricuspid regurgitation (TR) using the modified Bernoulli equation. There was a good correlation between Doppler and catheterization for RVSP (r = 0.83 pre valvuloplasty; r = 0.87 post valvuloplasty). Right ventricular systolic pressure by Doppler was 56 +/- 4 mm Hg before valvuloplasty and 48 +/- 4 mm Hg immediately afterwards (p < 0.001). Nine patients had TR on follow-up Doppler studies with an estimated RVSP of 53 +/- 9 mm Hg (p = NS compared with pre- and post-valvuloplasty values). Six of these nine patients had moderate or severe mitral regurgitation (MR), compared with one patient without TR at follow-up (p < 0.05). There appears to be a good correlation between the RVSP determined by Doppler and measured at catheterization.(ABSTRACT TRUNCATED AT 250 WORDS)