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Biomedical subjects

Shereif H Rezkalla

Publications and source records attributed to Shereif H Rezkalla.

16 recordsLinked to original sources
PubMed2006

Preconditioning, postconditioning and their application to clinical cardiology.

Ischemic preconditioning is a well-established phenomenon first described in experimental preparations in which brief episodes of ischemia/reperfusion applied prior to a longer coronary artery occlusion reduce myocardial infarct size. There are ample correlates of ischemic preconditioning in the clinical realm. Preconditioning mimetic agents that stimulate the biochemical pathways of ischemic preconditioning and protect the heart without inducing ischemia have been examined in numerous experimental studies. However, despite the effectiveness of ischemic preconditioning and preconditioning mimetics for protecting ischemic myocardium, there are no preconditioning-based therapies that are routinely used in clinical medicine at the current time. Part of the problem is the need to administer therapy prior to the known ischemic event. Other issues are that percutaneous coronary intervention technology has advanced so far (with the development of stents and drug-eluting stents) that ischemic preconditioning or preconditioning mimetics have not been needed in most interventional cases. Recent clinical trials such as AMISTAD I and II (Acute Myocardial Infarction STudy of ADenosine) suggest that some preconditioning mimetics may reduce myocardial infarct size when given along with reperfusion or, as in the IONA trial, have benefit on clinical events when administered chronically in patients with known coronary artery disease. It is possible that some of the benefit described for adenosine in the AMISTAD 1 and 2 trials represents a manifestation of the recently described postconditioning phenomenon. It is probable that postconditioning--in which reperfusion is interrupted with brief coronary occlusions and reperfusion sequences--is more likely than preconditioning to be feasible as a clinical application to patients undergoing percutaneous coronary intervention for acute myocardial infarction.

Adenosine↗
PubMed2006

Suspected clopidogrel resistance in a patient with acute stent thrombosis.

BACKGROUND: A 67-year-old man with supraventricular tachycardia associated with angina underwent coronary angiographic assessment. This investigation revealed mild coronary artery disease in his left main coronary artery and significant stenosis of the ramus medianus (left intermediate artery). A drug-eluting stent was deployed and treatment with clopidogrel and eptifibatide started. The patient subsequently developed chest pain accompanied by hypotension, hypoxemia and electrocardiographic changes that indicated acute myocardial infarction. Emergency angiography revealed occlusion of the ramus medianus despite clopidogrel therapy. INVESTIGATIONS: Coronary angiography, hypercoagulable work up and platelet function tests. DIAGNOSIS: Acute stent thrombosis and suspected clopidogrel resistance, culminating in ST-segment elevation myocardial infarction after percutaneous coronary intervention. MANAGEMENT: Warfarin, aspirin and clopidogrel drug therapy.

Aged↗
PubMed2006

Lipid-rich plaque masquerading as a coronary thrombus.

A 43-year-old woman presented with exertional chest pressure. Right coronary angiography showed a clear filling defect. Intravascular ultrasound revealed a plaque with 80% stenosis and a large lipid pool. Therefore, a stent was placed, and the patient became angina-free. Lipid-rich plaques are a cause of angiographic filling defects. Intravascular ultrasound is an integral part of coronary artery evaluation.

Adult↗
PubMed2006

Ischemic preconditioning for the clinician.

Ischemic preconditioning is a physiologic phenomenon that occurs in the cardiac muscle in which brief episodes of ischemia protect the heart when exposed to a sustained ischemia. Clinical counterparts include potential benefits of preinfarction angina and less ischemia after a second, compared to a first, coronary angioplasty balloon inflation. This article will discuss how preconditioning might be applied to the clinical setting during acute myocardial infarction, coronary interventions, and cardiac surgery.

Humans↗
PubMed2005

Coronary No-reflow Phenomenon.

No-reflow occurs in up to one third of patients with acute myocardial infarction during acute percutaneous intervention, and occasionally during elective interventions, particularly vein graft intervention. Multiple intracoronary medications will restore flow in most cases. We begin with 100 to 1000 mg of nitroprusside, verapamil, or adenosine at a similar dosage. We give it at 100-mg increments at high velocity. We inject it distally in the epicardial artery to avoid any systemic effect, and we do it through an intracoronary perfusion catheter. At times, we use prophylactic injections (prior to balloon inflation), particularly in vein graft intervention. Most of these strategies are not formally approved for treating no-reflow. However, reversing this condition with restoration of normal coronary flow is essential for an improved left ventricular function and a better cardiac outcome.

Journal Article↗
PubMed2004

Cardiac protection during acute myocardial infarction: where do we stand in 2004?

Despite better outcomes with early coronary artery reperfusion for the treatment of acute ST-elevation myocardial infarction (MI), morbidity and mortality from acute myocardial infarction (AMI) remain significant, the incidence of congestive heart failure continues to increase, and there is a need to provide better cardioprotection (therapy that reduces the amount of necrosis that may be coupled with better clinical outcome) in the setting of AMI. Since the introduction of the concept of cardiac protection over a quarter of a century ago, various interventions have been investigated to reduce myocardial infarct size. Intravenous beta-blockers administered in the early hours of infarction were clearly shown to be of benefit. Intravenous adenosine appeared promising for anterior wall AMIs, as did cariporide in some studies. Glucose-insulin-potassium infusion was beneficial in certain subgroups of patients, particularly diabetics. A variety of other medications were studied with negative or marginal results. The best strategy to limit infarct size is early reperfusion with percutaneous coronary stenting or thrombolytic therapy. Stenting is superior and should be adopted whenever there is a qualified laboratory available. Available resources should focus on decreasing time from onset of symptoms to start of reperfusion and maintaining vessel patency. Future studies powered to better assess clinical outcome are needed for adjunctive therapy with adenosine, K(ATP) channel openers, Na(+)/H(+) exchange inhibitors, and hypothermia.

Adenosine↗
PubMed2004

Ischemic preconditioning and preinfarction angina in the clinical arena.

In animals, brief episodes of ischemia before a total coronary occlusion protect the heart and result in a smaller myocardial infarct size. In humans, episodes of angina before acute myocardial infarction might also confer a preconditioning or protective effect; numerous studies show that preinfarction angina is associated with smaller infarcts. Preinfarction angina is also associated with reductions in ventricular dysfunction, arrhythmias and incidence of no-reflow phenomena, and, in some cases, improved survival. The protective effect of preconditioning in humans is characterized by marked individual variations and seems to be attenuated in women, people with diabetes and the elderly. Exercise seems to be an important way to induce preconditioning in humans and preserves it in the elderly.

Angina Pectoris↗
PubMed2004

Effectiveness of acetylcysteine on preventing renal dysfunction in patients undergoing coronary procedures.

OBJECTIVE: Experimental studies have shown that acetylcysteine is beneficial in preserving kidney function during coronary procedures. However, its role in routine clinical practice is not known. METHODS: We studied 75 consecutive patients undergoing coronary procedures who received acetylcysteine, and compared them with 56 consecutive similar patients who served as control. All patients had renal dysfunction, and a single operator did all procedures. RESULTS: Patients in the acetylcysteine group had a decrease in serum creatinine of 0.1 +/- 0.3 mg/dl versus a rise of 0.2 +/- 0.6 mg/dl in the control group (P<0.001). When the benefit in the active drug group was correlated with baseline creatinine, it occurred in all patients, regardless of the degree of kidney dysfunction. CONCLUSION: We conclude that in patients with varying degrees of renal dysfunction who undergo coronary procedures, acetylcysteine should be used in addition to hydration. It should be an accepted clinical practice that should be adopted routinely in the cardiac catheterization laboratory.

Acetylcysteine↗
PubMed2003

Eptifibatide-induced acute profound thrombocytopenia presenting as refractory hypotension.

A 61-year-old woman presented with acute coronary syndrome and was given heparin and eptifibatide in conjunction with coronary angioplasty. Shortly thereafter she became profoundly thrombocytopenic (platelets 2.0 x 10(9)/L) and developed severe refractory hypotension. Heparin-induced antibodies were not detected, but the patient developed strong eptifibatide-dependent antibodies specific for platelets that appear to explain both the thrombocytopenia and the hypotensive episode.

Acute Disease↗
PubMed2003

Coronary no-flow and ventricular tachycardia associated with habitual marijuana use.

A 34-year-old man reported heart fluttering and near syncope a few hours after marijuana smoking. In the emergency department, he was found to have a right bundle-branch-type ventricular tachycardia. The patient underwent a successful electric cardioversion. Coronary angiography showed no pericardial artery stenosis yet very slow coronary blood flow. Clinical tachycardia was also inducible in the electrophysiologic laboratory. After verapamil therapy and cessation of marijuana, his coronary flow normalized and ventricular tachycardia was no longer inducible in the electrophysiologic laboratory. Marijuana use might affect coronary microcirculation and cause ventricular tachycardia. Verapamil therapy and cessation of smoking might be curative.

Adult↗
PubMed2003

Successful direct stenting guided by intravascular ultrasound without contrast in a patient with renal dysfunction.

We report a 60-year-old male with significant renal dysfunction who had a recent coronary angiography with mid coronary stenosis. To avoid worsening of his kidney failure, we performed primary stenting with a combination of intravascular ultrasound and a marker wire. No dye was used during the stenting procedure. Whereas this new technique needs to be validated in studies, it represents new hope for such patients.

Acetylcysteine↗
PubMed2003

Antiplatelet therapy from clinical trials to clinical practice.

A platelet-rich clot at the site of severe coronary stenosis, plaque erosion, or a recent plaque rupture is the common etiology of acute ischemic syndromes. Thus, antiplatelet therapy is the cornerstone in the management of these conditions. Aspirin in a dose ranging from 160 to 325 mg once daily should be administered to virtually all patients. In patients with severe disease, particularly those who have no acute angiography, clopidogrel (Plavix, Bristol-Myers Squibb/Sanofi Pharmaceuticals) in a dose of 75 mg once daily should add to the benefit of aspirin for up to a year after the event. Clopidogrel also is an alternative to aspirin where a true aspirin allergy exists. Intravenous platelet glycoprotein IIb/IIIa receptor inhibitors demonstrated a robust benefit when used in conjunction with coronary intervention and thus far have no role in medical therapy alone. Oral platelet glycoprotein IIb/IIIa receptor inhibitors are of no clinical value.

Clinical Trials as Topic↗
PubMed2003

Contrast nephropathy.

Contrast nephropathy will increase mortality up to 30% following angiographic procedures. Before performing such procedures a careful reassessment of the risk/benefit ratio should be performed. Mannitol and diuretics play no role in prevention. Hydration and correction of abnormal electrolyte levels should be done in all patients. Pre-treatment with acetylcysteine and theophylline is a well-accepted strategy and should always be utilized. If creatinine levels are above 2.5 to 3 mg/dl, fenoldopam may provide additional protection, particularly in diabetic patients. However, the role of fenoldopam is controversial. Prophylactic hemodialysis may prove to be an additional tool in the fight against this disease in selected patients.

Acute Kidney Injury↗
PubMed2002

Myocardial infarction temporally related to ephedra--a possible role for the coronary microcirculation.

Myocardial infarction has been reported with ephedrine and pseudoephedrine use. It has been suggested that these agents may induce coronary artery spasm, hypercoagulable states, or oxygen demand imbalance. We report a 25-year-old male with myocardial infarction after receiving a diet pill containing ephedra. Coronary angiography revealed normal coronary arteries with very slow flow, suggestive of microcirculation abnormalities. The flow responded promptly to intracoronary verapamil.

Adult↗