Importance of potassium in cardiovascular disease.

The pivotal role of potassium (K+) in cardiovascular disease and the importance of preserving potassium balance have become clinical hot points, particularly as relates to new and emerging cardioprotective and renoprotective therapies that promote potassium retention. Although clinicians may be aware of the critical nature of this relationship, quite frequently there is some uncertainty as to the best way to monitor potassium levels in the face of a host of pathologic states and/or accompanying drug therapies that affect serum levels and/or total body potassium balance. Moreover, guidelines for monitoring of serum potassium levels are at best tentative and oftentimes are translated according to the level of concern of the respective physician. To address these uncertainties, an expert group was convened that included representatives from multiple disciplines. They attempted to reach consensus on the importance of K+ in hypertension, stroke, and arrhythmias as well as practical issues on maintaining K+ balance and avoiding K+ depletion. Because of the complexity of this topic, issues of hyperkalemia will be addressed in a forthcoming manuscript.

Feasibility of photopheresis to reduce the occurrence of restenosis after percutaneous transluminal coronary angioplasty: a clinical pilot study.

BACKGROUND: Photopheresis was evaluated as a means of preventing restenosis on the basis of immune modulation. METHODS: This was a prospective, randomized, controlled clinical trial analyzing clinical restenosis at 6 months after percutaneous transluminal coronary angioplasty (PTCA). Seventy-eight patients with single-vessel angioplasty were randomly assigned to a control group of 41 patients and a treatment group of 37 patients. At 6 months, there were 72 evaluable patients: 39 control patients and 33 treated. Twenty-nine control patients received balloon PTCA only and 10 patients received stents. Twenty treated patients received PTCA only and 13 patients received stents. Baseline clinical characteristics of both groups were similar. The treatment group received photopheresis for a total of 5 treatments. Primary end points were death from any cause, myocardial infarction, ischemia, and repeat revascularization procedures. RESULTS: By intention-to-treat analysis, clinical restenosis occurred in 27% of control patients versus 8% of treated patients (P =.040, relative risk = 0.30). CONCLUSIONS: Photopheresis therapy in patients undergoing balloon PTCA with and without stent deployment has been shown to be effective in reducing restenosis. The use of photopheresis in such patients merits further investigation.

Intravenous beta-blockers in acute myocardial infarction: perceived versus actual use by cardiologists and emergency physicians.

This study sought to determine the relationship between perceived and actual use of intravenous beta-blockers by cardiologists and emergency physicians for patients with acute myocardial infarction (AMI). The charts of 35 patients who presented to the emergency department of a community hospital with AMI during a 6-month period were retrospectively reviewed. Members of the departments of cardiology and emergency medicine were mailed a one-page survey pertaining to their use of intravenous beta-blockers in AMI. Of the 35 patients only 4 (11%) received an intravenous beta-blocker. Three of these 4 patients were either hypertensive or tachycardic and none had a contraindication to beta-blockade. A contraindication was present in 15 (48%) of those who did not get intravenous beta-blockade. The survey was completed by 11 (100%) of the emergency physicians and 68 (69%) of the cardiologists. Emergency physicians were significantly less likely to report using intravenous beta-blockers in AMI patients who were normotensive with normal heart rates (P=.007) and most (9 of 11) deferred the decision to the cardiologist. Although the majority of cardiologists reported giving an intravenous beta-blocker to at least 50% of AMI patients with normal blood pressure and pulse rates, the actual frequency was only 8% (1 of 13). In this institution, cardiologists overestimated the frequency of intravenous beta-blocker administration to patients with AMI. Emergency physicians usually deferred the decision on intravenous beta-blockers to cardiologists and reported a frequency of use that was much closer to actual practice.

Flecainide induced atrial tachycardia with 1:1 ventricular conduction during exercise testing.

Wide complex tachycardias may represent a rare proarrhythmic effect of some antiarrhythmic agents. The authors describe a patient who developed a wide complex tachycardia developing during stress testing while on therapy with flecainide, and the difficulty in interpreting the electrocardiogram. This article reviews potential proarrhythmic effects of flecainide in the treatment of atrial dysrhythmias and the difficulty in differentiating associated wide complex tachycardias.

Accuracy of SPECT thallium studies in a community hospital.

The present study shows an overall accuracy to the Cedars-Sinai trial on a patient and a combined vascular territory basis. These results suggest SPECT thallium studies can provide information despite the referral biases and unselected patient population inherent in a busy clinical practice.

Effects of inhibitors of angiotensin-converting enzyme on regional hemodynamics.

Inhibitors of angiotensin-converting enzyme (ACE) exert favorable regional hemodynamic effects at various sites. In patients with essential hypertension, ACE inhibitors reduce renal vascular resistance while enhancing renal blood flow, glomerular filtration rate, and acute and sustained natriuresis. Whereas these agents may either reduce or have no effect on hepatic blood flow, they are associated with reduced splanchnic resistance. ACE inhibitors reduce total peripheral resistance and may maintain limb blood flow. In normal subjects, they augment blood flow to skeletal muscle and skin and reduce peripheral resistance in vessels supplying these regions. ACE inhibitors appear to exert a vasodilatory effect on large arteries as well as arterioles. Dilatation is often accompanied by significant improvements in arterial compliance, possibly due to direct effects of the renin-angiotensin system on the arterial wall. Reduction of blood pressure is generally not accompanied by reduced cerebral blood flow. Enhanced tissue effects of newer ACE inhibitors such as quinapril may result in improved regional hemodynamic effects.

Preliminary hemodynamic report of the efficacy and safety of quinapril in acute and chronic treatment of patients with congestive heart failure.

A two-part hemodynamic trial of the efficacy and safety of quinapril hydrochloride was conducted in 26 patients with congestive heart failure (NYHA Class III or IV) who had not optimally responded to treatment with diuretics and digitalis. A total of 25 patients had evaluable data after receiving single doses (2.5, 5, or 10 mg) of quinapril. Following acute dosing, favorable hemodynamic changes began within thirty minutes to one hour and usually reached a maximum within four hours post-dose. Nineteen evaluable patients who had responded to acute therapy received an additional sixteen weeks of chronic treatment with quinapril in individualized dosage regimens. Hemodynamic responses did not differ markedly between acute and chronic therapy. Favorable hemodynamic responses were maintained or enhanced following chronic doses of 5 to 30 mg/day (given either once daily or in divided doses). The most frequent doses were 10-15 mg/day in divided doses. The mean maximum percent changes in four primary hemodynamic parameters after chronic dosing (compared with baseline) were: mean arterial blood pressure, -3.9%; pulmonary capillary wedge pressure, -39.7%; cardiac output, +31.7%; and systemic vascular resistance, -25.2%. Changes in heart rate and mean arterial blood pressure did not result in clinically significant bradycardia or hypotention. Overall, quinapril produced both acute and sustained beneficial hemodynamic effects in patients whose congestive heart failure was not clinically controlled with diuretics and digitalis.

Long-term clinical course of patients with normal coronary arteriography: follow-up study of 121 patients with normal or nearly normal coronary arteriograms.

To determine the long-term course of patients with normal coronary arteriograms, follow-up data regarding frequency of morbid cardiac events and extent of persistent clinical disability were obtained in 121 patients (72 women, 49 men; mean age 49 years) with normal (90%) or nearly normal (10%) coronary arteriograms. Mean length of follow-up was 4.3 years (range 1 to 11 years). Three (2.5%) patients died suddenly and unexpectedly. Four (3.4%) surviving patients suffered documented acute myocardial infarction (AMI) subsequent to initial arteriography. Three of seven patients who underwent repeat coronary arteriography were found to have disease in excess of that observed on initial arteriograms. The overwhelming majority (94% or 80%) of surviving patients continued to experience chest discomfort similar to that for which they underwent coronary arteriography and 75 (64%) continued to use antianginal drugs. Thus the finding of normal or nearly normal coronary arteriograms implies a highly favorable prognosis, although it does not establish immunity from a morbid cardiac event (AMI and/or sudden death); the likely basis for these events is progression of fixed obstructive disease, rather than coronary artery spasm or underestimation of extent of coronary disease by arteriography.

Fracture of pacing electrode mimicking failure of pulse generator.

To our knowledge, this is the first reported case of spontaneous fracture of a pacing electrode with decreased amplitude of the pacing artifact, failure to capture, and intact sensing. We postulate that the difference in impedance of the pacemaker for sensing and stimulation may account for this phenomenon.

Coronary artery disease in an 18 year old with pseudoxanthoma elasticum: successful surgical therapy.

An 18 year old girl with pseudoxanthoma elasticum, a 7 year history of angina pectoris and evidence of an old anteroseptal myocardial infarction was found on coronary angiography to have three vessel coronary artery disease. A triple coronary artery-saphenous vein bypass graft was performed, and she has been asymptomatic for 1 year. Histologic examination of a segment of the right coronary artery revealed changes consistent with the vascular lesion of pseudoxanthoma elasticum.