The Journal of Tehran University Heart Center
Volume:1 Issue: 3, Jul 2006

The application of magnetic resonance to diagnostic medical imaging stands as one of the great scientific achievements in the past 50 years. Magnetic resonance techniques are easily applied to organs which remain stationary during the imaging procedure, such as the brain and musculoskeletal system. Imaging of moving heart structures and circulating blood is considerably more difficult. Clinical application of magnetic resonance to the cardiovascular system remains challenging but continuing technological innovations have enabled cardiovascular specialists to more effectively utilize magnetic resonance in clinical practice as well as for innovative research. Cardiovascular magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) are now being used with increasing frequency for the assessment of patients with cardiovascular disease. This paper will introduce clinicians to the current applications of these flexible and robust tools. A brief introduction will be given to the physics of MRI, the instrumentation and the imaging strategies. The main focus of the article, however, is to review how these techniques are being applied by clinicians in routine daily care.

Diagnosis of coronary artery disease (CAD) in patients with left bundle branch block (LBBB) is considered as a challenge in cardiology due to the low accuracy of noninvasive methods such as basal and stress electrocardiography (ECG). This diagnostic challenge can be reduced but not eliminated using dipyridamole as a stress method instead of exercise. The aim of this study was to assess the diagnostic value of dipyridamole stress Tc-99m Sestamibi single photon emission computed tomography (SPECT) myocardial perfusion imaging in patients with complete LBBB. We studied 40 patients with permanent and complete LBBB using Tc-99m Sestamibi SPECT and dipyridamole stress to evaluate CAD. Perfusion defect was considered fixed when there was no difference between rest and stress score, while reversible defect was defined as a segment with higher score on stress images. All patients underwent coronary angiography. Eleven patients (27.5%) had normal myocardial perfusion SPECT and 29 patients (72.5%) had reversible perfusion defects. Angiography was positive in 30 patients, while 10 cases showed normal angiography. The sensitivity, specificity, positive predict value and negative predict value of our study for detecting >50% coronary stenosis was 86.6%, 70%, 89% and 64% respectively. We found 33 (82.5%) patients with concordant angiography and myocardial perfusion SPECT results (p=0.002). Angiography was positive in 90% of patients with reversible perfusion defects on myocardial perfusion SPECT. In summary, Tc-99m Sestamibi SPECT in patients with LBBB showed high accuracy (82.5%) in detecting >50% coronary stenosis.

The aim of this study was to echocardiographically assess the effects of EECP (Enhanced External Counterpulsation Therapy) therapy on systolic and diastolic cardiac function. LVEF (left ventricular ejection fraction), ESV (end-systolic volume), EDV (end-diastolic volume), Sm (myocardial systolic wave), Ea (myocardial early diastolic wave), Vp (propagation velocity), E/Ea (peak early diastolic transmitral flow velocity/Ea), E/Vp and diastolic function grade were studied in twenty-five patients before and after 35 hours of EECP. EECP reduced ESV and EDV and increased EF significantly (p=0.018, 0.013, 0.002, respectively) in patients with baseline LVEF≤50%, but not in patients with baseline LVEF>50%. Patients with E/Ea≥14 had a significant reduction in EDV and ESV (p=0.038 and 0.32, respectively) and an increase in LVEF (p=0.007) after EECP, whereas patients with baseline E/Ea<14 had no significant change in these parameters. Similarly, EECP significantly improved ESV, EDV and LVEF (p=0.014, 0.032, 0.027 respectively) in patients with grades II and III of diastolic dysfunction (decreased compliance) at baseline, but not in patients with normal diastolic function or grade I diastolic dysfunction (impaired relaxation). Patients with Ea<7 cm/sec prior to EECP showed significant improvement in EDV, ESV and LVEF after therapy (p=0.024, 0.015, 0.001), while patients with Ea ≥7cm/sec showed no significant change. Similarly, patients with Sm<7cm/sec prior to EECP showed significant improvement in EDV, ESV and LVEF after EECP (p=0.016, 0.017, 0.006), while patients with Sm ≥7cm/sec did not. These results provide new insight into the hemodynamic effectiveness and potential clinical applications of EECP.

Dialysis patients frequently have coronary artery disease but are regarded as high risk patients for coronary artery bypass grafting (CABG). Between February 2002 and September 2006, seventeen dialysis-dependent patients underwent isolated CABG at our center. CABG was performed under cardiopulmonary bypass (CPB) for all the patients. All cases had been maintained on hemodialysis and the duration of preoperative hemodialysis ranged from 6 to 24 months (mean 13.4±6.4). The patients’ characteristics, clinical and operative data as well as perioperative and mid-term outcome were reviewed. All patients were men with a mean age of 53±8.4 years. Mean preoperative ejection fraction was 45.5%±10.4% (range 25 to 60 %). One internal mammary graft was used in 16 (94.1%) patients. Cardiopulmonary bypass and aortic cross-clamp times were 71.3±18.7 and 40.5±8.3 minutes respectively. The more frequent complication was prolonged mechanical ventilation in 2 (11.7%), there was no perioperative mortality. In mid-term follow-up (mean time: 11.8±9.5 months) the mid-term mortality rate was 20% (3 patients). CABG in chronic renal dialysis patients can be accomplished with acceptable short and mid-term morbidity and mortality.

ژ To evaluate the frequency, clinical presentation and cardiac involvement of children with RF in the North-East of Iran. A case series analysis was conducted on 80 patients with acute rheumatic fever (ARF), who were hospitalized at Ghaem hospital in Mashad between 1994 and 2000, were studied. Laboratory tests and results from echocardiographic examinations, and clinical findings were analyzed. All patients received standard care for children with ARF. The 2 test was used for comparison of binary data. When compared to similar studies from developed countries, our study demonstrates a decreased frequency of RF in North-East Iran over the past few years. However, it is still a major health problem and the most common cause of acquired heart disease in childhood. The distribution of the major modified Jones criteria in our study is slightly different from that described in the literature, with a higher incidence of carditis. It appears that carditis is endemic in this region. Considering the high morbidity and complications involved in this disease, there is an immediate need for effective preventive programs for the initiating cause streptococcal infections, especially since it is treatable.

This study sought to access differences in long-term (9 months) outcomes between Acute Coronary Syndrome (ACS) patients who undergo early intervention compared to Percutaneous Coronary Intervention (PCI) in stable and refractory conditions. Data originated from Tehran Heart Center Registry- interventional cardiology (THCR-IC) and consisted of 1267 patients divided into two categories; 227 patients had features corresponding to acute coronary syndromes (17.9%) and 1040 patients suffered from stable angina (82.1%). They were admitted between April 3, 2003 and April 25, 2004. The clinical success rate of PCI was higher in ACS (97% vs. 94%; P=0.037), while In-hospital complications were similar in both groups. During the follow-up period, clinical restenosis was not significantly different and the overall number of re-interventions caused by restenosis or progression was not more frequent in ACS patients. Also, 1.3% of ACS and 0.4% of SA patients died, but the difference was not statistically significant (P=0.16). Finally, Major Adverse Cardiac Events (MACE) showed no significant difference (5.2% vs. 3.9%; P=0.42). Multivariate analysis showed that female sex (OR=25.6; P=0.003) and previous history of PCI (OR=8.4; P=0.016) were the only strong independent risk factors for major adverse cardiac events. Analyzing ACS patient outcomes using Mantel-Hanzel analysis showed that the female sex was the only factor which strongly increased the incidence of MACE. Both ACS and SA patients who underwent coronary intervention had similar in-hospital and composite major adverse cardiac events, nevertheless female gender must be considered as an independent risk factor for major adverse cardiac events especially in patients with acute coronary syndrome who undergo PCI.

To determine factors that predicts ICU and ward stay during hospitalization for coronary artery surgery. Data were collected retrospectively from 200 patients. ICU and ward stay time was divided into two groups and compared by X2 and t test and variables with a p value of less than 0.1 were included in logistic regression model. Specificity and sensitivity of tests were examined by ROC curve. Mean time of ICU and ward stay (day) was 3.89 and 11.07 days respectively. The mean volume of transfused blood in group 1 (ICU stay≤3 day) was 694 ml and in group 2 (>3 day) was 1231 ml where the difference was significant (p<0/05) and this correlation between stay time and transfusion was not seen in ward stay. In univariate analysis, factors such as transfused volume, maximum flow, Chronic obstructive pulmonary disease (COPD), Ejection fraction (EF), Intra aorta pump (IABP) and drainage volume were different between two groups of ICU stay times and such factors in ward stay were transfused volume, minimum flow, COPD, reoperation due to bleeding, and amount of 24 hours bleeding. In logistic regression model variables such as age, pump time, transfused volume and COPD were predictors of ICU stay and only drainage volume was predictor of ward stay. Transfusion of blood is associated with long ICU stay time. Mechanism of this increased time is depression of immune system and increased rate of infection. Volume of bleeding from chest tube in 24 hours is associated with long hospital stay, because chest tube dose not pull out until drainage volume reduced to 50 ml in 24 h

Percutaneous transcatheter closure has been proposed as an alternative to surgical closure or long-term anticoagulation in patients with presumed paradoxical embolism and patent foramen ovale (PFO). There were two symptomatic patients (29 and 47 years old) who underwent percutaneous transcatheter closure of PFO after at least two events of cerebral ischemia; one embolic event had occurred under anti-platelet therapy. For both patients, Amplatzer PFO occluder measuring 25 mm in diameter were used. In both cases, complete occlusion by color Doppler and transesophageal contrast echocardiography investigation was achieved after the procedure and lasted at least up to 3 months after implantation as determined by our follow up. Mean fluoroscopy time was 16.7 minutes. Percutaneous transcatheter closure was technically successful in both patients (100%). No residual shunt was seen at the end of the procedure or in follow-ups. In-hospital follow-up was uneventful. At a mean follow-up of 3 months, no recurrent embolic neurological events were observed. Transcatheter closure of PFO with Amplatzer PFO occluder devices is a safe and effective therapy for patients with previous paradoxical embolism PFO. Percutaneous closure is associated with a high success rate, low incidence of hospital complications, and freedom of cerebral ischemic events.

: A 45- year old man with a history of Aortic Valve replacement presented with acute chest pain which was diagnosed to be anterior wall myocardial infarction. He received thrombolytic therapy with streptokinase. Echocardiography and fluoroscopy showed normally functioning ball and cage aortic prosthesis. Coronary arteriography showed globular filling defect in midportion of left anterior descending coronary artery, most probably embolized thrombus. The patient underwent medical treatment especially warfarin with higher range of INR without any intervention. He had a smooth in-hospital course and uneventful recovery.