Computer-assisted myocardial thickening analysis of gated MIBI SPECT images.

RATIONALE AND OBJECTIVES: The purpose of this study is to use the relationship between the partial volume effect, count density, matrix size, and reconstruction filter in gated single photon emission computer tomography (SPECT) to recover myocardial thickness, and to validate measurements generated using a computer-assisted automatic contour method with a phantom model and with thickness changes measured by echocardiography. METHODS: Regional myocardial contour was defined automatically using shape constraints, gray level thresholding, and a gradient method applied to gated technetium-99m (99mTc)-methoxy-isobutyl-isonitile (MIBI) SPECT images. A heart phantom with wall thickness ranging from 0.8 cm to 1.3 cm was constructed. SPECT images were acquired and reconstructed using different matrix sizes, count densities, and filters. Wall thickness determinations derived from the reconstructions made with each combination of matrix size, type of filter, and cutoff frequency were correlated with the measured thicknesses. The best combination was applied to the gated MIBI SPECT images of 55 patients who also had echocardiography and coronary arteriography. Count density measurements were made across each regional myocardial segment to evaluate wall thickness at end-diastole and end-systole. Systolic wall thickening measurements made with this automated computer-assisted contour technique were compared with echocardiographic measurements made from segments with normal perfusion and from regions containing infarcted tissue. RESULTS: Different reconstruction filters and cutoff frequencies affected the accuracy of measurements of myocardial wall thickness determined from gated myocardial SPECT images. A matrix size of 64 x 64, with a minimum of 10 counts/pixel/frame, and use of a Hanning filter with 0.5 cyc/cm cutoff frequency gave the best combination for myocardial thickness determination and spatial resolution. Application of these factors to the phantom yielded results that correlated very well with the thickness measurements (r = 0.986, P < 0.001). Application of the technique to the clinical SPECT studies yielded measurements of myocardial wall thickening that were not significantly different from that determined by echocardiography. CONCLUSION: Computer-assisted contour analysis of gated SPECT images enables accurate determination of regional wall thickening using the count density changes within each myocardial segment.

Survival in Infarct Related Intramyocardial Dissection Importance of Early Echocardiography and Prompt Surgery.

Infarct related intramyocardial dissection, an unusual mechanical complication associated with recent inferior/inferoposterior myocardial infarction, is characterized by a septal defect and a dissection tract that originates on the left side of the interventricular septum, extends beyond the septum into the right ventricular free wall, and subsequently re-enters the right ventricle. The utility of echocardiography for diagnosis has been described. Despite aggressive therapy, the prognosis of intramyocardial dissection is reported to be dismal. We describe the use of prompt echocardiography in two patients, which established the diagnosis of infarct related intramyocardial dissection allowing early definitive surgery and long-term survival.

Severe calcific pulmonic valve stenosis and restrictive ventricular septal defect in a 64-year-old man. Results of percutaneous double balloon valvuloplasty.

The clinical and hemodynamic features of a 64-year-old symptomatic man with severe calcific pulmonic valve stenosis and restrictive ventricular septal defect are reported. Successful double balloon percutaneous pulmonic valvuloplasty immediately produced excellent symptomatic benefit and introduced expected and well tolerated hemodynamic changes. The transpulmonic valve peak systolic pressure gradient was reduced from 130 to 30 mmHg and pulmonary artery pressure increased to top normal levels acquiring normal pulse wave configuration. A left-to-right shunt, negligible prior to valvuloplasty, increased appreciably producing a pulmonary to systemic flow ratio of 1.7. Reevaluation at 5 months revealed sustained hemodynamic profile. Symptomatic benefit and tolerance to ordinary physical activities have remained excellent at 1 year follow-up.

Impact of the incidental diagnosis of clinically unsuspected central pulmonary artery thromboembolism in treatment of critically ill patients.

Mortality is high in unrecognized pulmonary embolism (PE), but the diagnosis is difficult to establish, especially in patients with coexisting cardiopulmonary disorders. We describe a group of 14 patients with pulmonary thromboemboli in whom transesophageal echocardiography (TEE) performed for coexisting cardiopulmonary conditions established the clinical diagnosis of PE not suspected prior to TEE. The patients had initial clinical diagnoses of heart failure (eight patients), cardiogenic shock (two patients), atrial septal defect (two patients), aortic dissection (one patient), and pneumonia (one patient). Thirteen patients had risk factors for PE. Transthoracic echocardiography (TTE) demonstrated right heart strain in eight patients but did not visualize PE in any of the patients. The TEE diagnosis of occult central pulmonary artery thromboembolism changed treatment in all 14 patients. Ten of the 14 patients were successfully discharged from the hospital. We conclude that occult central pulmonary artery thromboemboli are not uncommon in patients presenting with acute cardiopulmonary disorders and the presence of risk factors for PE and right heart strain on TTE should alert the physician to suspect PE. If and when TEE is performed in patients with acute cardiopulmonary disorders with risk factors for PE and right heart strain, the physician should evaluate the main pulmonary artery and its branches for central pulmonary artery thromboemboli.

Dual-balloon progressive coronary dilatation catheter: design and initial clinical experience.

As newer interventional devices continue to enter the marketplace, balloon angioplasty remains the standard by which all devices are judged with regard to both safety and efficacy. It has been observed that predilating a stenosis with a small balloon followed by dilatation with an optimally sized larger balloon creates a more controlled arterial injury, reduces complications, and thus improves success rates. Exchanging two balloons for each lesion, however, increases the complexity and cost of the procedure in addition to increasing the amount of time required and the amount of radiation exposure. Therefore an "over-the-wire" dual-balloon catheter was developed with a small distal balloon and a larger proximal balloon on a 2.9F shaft to allow progressive coronary dilatation with a single device, without necessitating a balloon catheter exchange. The device was used successfully in 45 of 47 patients (78 lesions). The two failures were related to an inability to cross the lesion in one and failure of the device in the other. Twenty-one patients (47%) underwent a multivessel procedure. There were 29 left anterior descending/diagonal, 17 circumflex/marginal, 20 right coronary artery/posterior descending artery, and 10 vein graft lesions. The device was successfully delivered in the native anatomy to 12 distal, 27 mid, and 27, proximal lesions of which nine were osteal, for a procedural success rate of 97%. The mean stenosis was reduced from 80.7 +/- 11.5% to 15.2 +/- 11.9%. There were no major dissections, only 9 (11.2%) minor dissections, and no myocardial infarctions.(ABSTRACT TRUNCATED AT 250 WORDS)

Subcutaneous heparin in postangioplasty management: comparative trial with intravenous heparin.

Abrupt closure of a coronary artery after successful angioplasty remains a problem for the interventionalist. Many laboratories continue to administer heparin intravenously for 12 to 24 hours in an attempt to alleviate this problem. But prolonged heparin therapy delays sheath removal and may lead to groin and vascular complications, and so prolong the hospital stay. To test the hypothesis that subcutaneous heparin was as efficacious as intravenous heparin in preventing acute closure while reducing the vascular complications associated with extended sheath placement, we prospectively randomized 151 patients to two groups. The intravenous group, 77 patients, received continuous intravenous heparin at 1000 units/hour for 12 to 18 hours; the subcutaneous group, 74 patients, received 12,500 units subcutaneously every 12 hours for three doses after sheath removal 2 to 3 hours after the angioplasty. The activated clotting time immediately after the angioplasty was 401 +/- 108 seconds in subcutaneous group, as compared with 368 +/- 67 seconds in the intravenous group (p = 0.028). Patients receiving subcutaneous heparin continued to show adequate anticoagulation, with a PTT of 85 +/- 21 seconds obtained approximately 12 hours after the procedure. The PTT at discharge was statistically greater in the subcutaneous group, at 49.2 +/- 21 seconds, versus 35.6 +/- 13 seconds in the intravenous group (p < 0.001). Abrupt occlusion was similar in both groups, but the hematomas and bleeding/oozing in the intravenous group was significantly higher when compared with that of the subcutaneous group, 16 versus 6 (p = 0.026) and 26 versus 7 (p < or = 0.002), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty of the septal perforators: acute outcome and long-term clinical efficacy.

Critical stenosis of a large septal perforator artery can cause significant myocardial ischemia. Since septal perforators are generally not accessible for bypass grafting, balloon angioplasty offers an excellent alternative for revascularization of these vessels. The short-term outcome and long-term clinical follow-up angioplasty of the septal perforator was evaluated retrospectively in 21 patients. Fourteen of the 21 (66%) had previous myocardial infarction, 9 of 21 (43%) had previous coronary bypass surgery, 10 of 21 (48%) had previous percutaneous transluminal coronary angioplasty (PTCA), and 6 of 21 (28%) had congestive heart failure. Additional PTCA of one or more vessels was undertaken in all patients. Primary success of PTCA of the septal perforator was achieved in 20 of 21 (95%) patients. The mean stenosis was improved from 89.8 +/- 10% to 18.4 +/- 11.7%. No acute closure, emergency coronary bypass, or myocardial infarction was observed or needed during hospital stay. At long-term follow-up (18 +/- 9 months), event-free survival was 95%. No cardiac death occurred. In 86% of cases, there was significant improvement in anginal class at 2 years. Five of the six patients with congestive heart failure showed marked improvement in functional class at 2 years. In conclusion, balloon angioplasty of the large septal perforator artery is technically feasible, with a high success rate, and does not increase the rate of acute complications of the procedure. Along with PTCA of other arteries, it provides long-term relief of angina in a majority of symptomatic patients with complex multivessel disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Progressive coronary dilation: an angioplasty technique that creates controlled arterial injury and reduces complications.

The incidence of dissection or acute closure during coronary angioplasty has remained unchanged in spite of increased operator experience and technologic advances. To test the hypothesis that progressive coronary dilation, that is, predilation of the stenosis with a smaller balloon (2.0 or 2.5 mm) and then maximal dilation with an optimally sized (3.0, 3.25, 3.5, 3.75, or 4.0 mm) balloon may produce controlled injury and thus reduce the incidence of major complications, the procedural success rate and acute complications of progressive coronary dilation were analyzed in 1087 patients (1486 vessels) and compared with other large series. To determine whether progressive coronary dilation would improve success rates for complex lesions, the last 167 vessels were also prospectively characterized by American College of Cardiology/American Heart Association criteria. Of the 1248 vessels with partial occlusions, the success rate was 98.7%. Attempts to dilate total occlusions in 16% (353) of vessels yielded a success rate of 88%. The primary success rates for types A, B, and C lesions were 100%, 97%, and 91%, respectively. Multivessel angioplasty with progressive coronary dilation was done in 32.4% of cases. Acute closure, major dissection, emergency coronary bypass, periprocedural myocardial infarction, and in-hospital death were noted in 1.4%, 1.3%, 0.7%, 0.8%, and 0.09% of the patients, respectively; the incidence was significantly lower than in previously reported series. Mean residual stenosis was 20.0% +/- 10.6%. Thus progressive coronary dilation by controlled injury to the plaque offers a high primary success rate; low residual stenosis; and markedly lower incidence of acute closure, major dissection, emergency coronary bypass, and death in dilation of both simple and complex lesions.

Effectiveness of decremental diameter balloon catheters (tapered balloon).

Natural tapering of coronary arteries from larger proximal to smaller distal diameters often creates a dilemma for optimal balloon sizing during percutaneous transluminal coronary angioplasty (PTCA). To demonstrate the need for new dilating catheters suitable for tapered coronary anatomy, 100 consecutive coronary arteries were measured by videodensitometry, 1 cm proximal and distal to the stenosis. In 23 arteries there was a 1 mm or greater taper and 19 arteries showed a 0.5 to 0.99 mm taper. Only 50 arteries showed a nearly uniform diameter at the site of the stenosis, and 8 arteries demonstrated reverse taper, i.e., distal was greater than proximal diameter. To avoid balloon size mismatch with significant tapering, decremental diameter balloon catheters were developed. Series I tapers from 3.5 to 3.0 mm and series II from 3.0 to 2.5 mm over a balloon length of 25 mm. Tapered balloons were used in 80 patients with 94 tapered coronary arteries. Before PTCA, proximal, stenotic and distal mean diameters measured 3.6, 1.1 and 2.6 mm, respectively; after PTCA, proximal, stenotic and distal diameters measured 3.6, 2.8 and 2.5 mm, respectively, thus maintaining the natural tapering after effective dilatation. Only 2 arteries (2.1%) showed significant dissection, with no abrupt occlusions, and none requiring bypass surgery. In summary, decremental diameter balloon catheters provide optimal dilation in tapered arterial segments with few complications and offer a new approach to balloon sizing.

Prevention of restenosis by lovastatin after successful coronary angioplasty.

Prevention of restenosis after successful percutaneous transluminal coronary angioplasty (PTCA) remains a major challenge. To determine whether lovastatin could prevent restenosis, between December 1987 and July 1988, a total of 157 patients undergoing successful PTCA were randomly and prospectively assigned to the lovastatin group or a control group. Seventy-nine patients received lovastatin (20 mg daily if the serum cholesterol level was less than 300 mg/dl and 40 mg daily if the serum cholesterol level was greater than or equal to 300 mg/dl) in addition to conventional therapy (lovastatin group). Seventy-eight patients received conventional therapy alone (control group). Fifty patients in the lovastatin group and 29 in the control group were evaluated with coronary angiography at an interval of 2 to 10 months (mean 4 months). The restenosis rate was evaluated according to the number of patients showing restenosis, the number of vessels restenosed, and the number of PTCA sites restenosed. Restenosis was defined as the presence of greater than 50% stenosis of the PTCA site. In the lovastatin group 6 of 50 patients (12%) had restenosis compared with 13 of 29 patients (44.4%) in the control group (p less than 0.001). When the number of vessels restenosed was considered, only 9 of 72 vessels (12.5%) restenosed in the lovastatin group compared with 13 of 34 vessels (38.2%) in the control group (p less than 0.002). Similarly, 10 of 80 (12.5%) PTCA sites restenosed in the lovastatin group compared with 15 of 36 (41.7%) in the control group (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term efficacy of percutaneous transluminal angioplasty on incidence of myocardial infarction, relief of symptoms and survival.

This study was conducted to determine the long-term effects of percutaneous transluminal coronary angioplasty (PTCA) on the incidence of myocardial infarction, survival, and relief of symptoms. A total of 124 patients were included in the study and were followed for 16 to 25 months. The success rate of PTCA was 91.2% and 160 stenoses were dilated. Fifty-nine patients had multivessel disease (MVD) and 54 had single-vessel disease (SVD). There was no difference in survival when patients with SVD were compared with those with MVD. The cardiac survival rate for both groups was greater than 98%. Nine patients had myocardial infarction in the area of the dilated artery: 3 patients (5.5%) with SVD and 6 patients (10.1%) with MVD. Ninety-six patients (84.9%) remained free of symptoms: 46 patients (85.2%) with SVD and 50 patients (84.7%) with MVD. These data demonstrate the long-term efficacy of PTCA in patients with SVD and MVD with regard to control of symptom of angina, improved survival, and prevention of myocardial infarction.

Low electrocardiographic voltage in pericardial effusion.

Although low ECG voltage has been associated with pericardial effusion, its diagnostic usefulness in such patients is unclear. When we examined the relationship between the volume of pericardial effusion and low voltage in 28 patients who underwent pericardial drainage, 14 patients exhibited low voltage (sum of limb lead QRS amplitudes of 30 mm or less). In eight patients, the QRS amplitude was 5 mm or less in each of the standard leads (absolute low voltage). There was no significant correlation between the volume of the effusion and the QRS amplitude (r = -0.30). This correlation did not improve (r = -0.37) when patients with left ventricular hypertrophy were excluded. Following pericardial drainage, the QRS amplitude increased in 21 of 24 patients and decreased in three. Low voltage persisted in nine patients; the pericardium was thickened in seven of the nine. Analysis of the sensitivity and specificity revealed acceptable sensitivity only with large effusions and no left ventricular hypertrophy. Absolute low voltage appeared to be specific in the diagnosis of moderate and large effusions among patients with pericardial effusion selected for this study.