Richard A. Moggio

Development of Decompensated Dilated Cardiomyopathy Is Associated With Decreased Gene Expression and Activity of the Milrinone-Sensitive cAMP Phosphodiesterase PDE3A

BACKGROUND Phosphodiesterase III (PDE3) inhibitors are inotropic agents used to treat congestive heart failure (CHF) and are less effective in patients with severe CHF. Little is known about relative changes in PDE3 activity or gene expression during the evolution of cardiomyopathy. METHODS AND RESULTS In the present study, we evaluated temporal changes in PDE3A gene expression before and after pacing-induced CHF in nine mongrel dogs. Three weeks of left ventricular (LV) pacing produced LV end-diastolic pressures of 15+/-1.7 mm Hg, whereas overt CHF at 4 to 5 weeks was associated with LV end-diastolic pressures of 24+/-1.7 mm Hg; prepacing values were 6.6+/-0.6 mm Hg. Total RNA isolated from LV tissues was analyzed on Northern blots; 10 unpaced normal hearts served as tissue controls. Signals for PDE3A mRNAs (7, 8, and 10 kb) or PDE4D (7.6 kb) were normalized against glyceraldehyde-3-phosphate dehydrogenase (GAPDH) or ribosomal 18S RNA. Before the onset of CHF, PDE3A/GAPDH ratios were not different between the control and 3-week paced groups. In contrast, all PDE3A/GAPDH ratios were selectively reduced by 52%, and PDE3A/18S was reduced by 70% (P<.05) in CHF; PDE4D/GAPDH (or 18S) was unchanged. LV tissues from four control and four CHF dogs were also processed to isolate cytosolic and microsomal membrane protein for cAMP PDE3 activity assays. CHF was associated with a significant 54% reduction (P<.05) in microsomal but not cytosolic PDE3 activity. CONCLUSIONS Selective downregulation of PDE3A may account in part for the ineffectiveness of milrinone in the treatment of severe CHF.

Hemodynamic comparison of albumin and hydroxyethyl starch in postoperative cardiac surgery patients.

The hemodynamic effects of 2 plasma volume expanders were compared in postoperative open heart surgery patients. Albumin 5% (A) or hydroxyethyl starch 6% (HES) solutions were infused according to indications based on cardiac index (CI) and pulmonary wedge pressure (WP), and their effects evaluated by physiologic profile measurements.Both groups demonstrated significant increases with volume infusion in CI (A from 2.37 to 2.84; HES from 1.97 to 2.49 L/min-m2) and WP (A from 9.4 to 13.7 mm Hg; HES from 11.9 to 13.2 mm Hg). Stroke index and stroke work increased similarly. Mean systemic arterial pressure (MAP) and mean pulmonary arterial pressure (MPAP) remained unchanged. No significant difference for any variable was demonstrated between the A and HES groups. In the volume used, from 250 to 750 ml, HES caused no bleeding abnormalities. HES is as effective as A as a plasma volume expander in postoperative cardiac surgery patients.

Simplified method for reoperation on the mitral valve.

Reoperation on the mitral valve is becoming more common because of the degeneration of bioprosthetic valves, endocarditis, and malfunction or thrombosis of mechanical valves. We advocate a technique that transforms a technically difficult operation into one that is much less tedious, time-consuming, and dangerous than reopening a sternal-split operative site the second, third, or fourth time. Favorable experience in 11 patients using right anterolateral thoracotomy without aortic or right atrial cannulation and without aortic cross-clamping or cardioplegia is presented.

MR imaging in the definition of coronary artery anomalies.

Coronary angiography remains the standard imaging technique to study coronary artery anatomy. Coronary artery aneurysms and fistulas are often incompletely visualized with routine angiography. Magnetic resonance (MR) imaging of such coronary anomalies is presented. The MR images improve the preoperative assessment of patients with coronary artery aneurysms and fistulas.

Downregulation of right ventricular phosphodiesterase PDE-3A mRNA and protein before the development of canine heart failure

Phosphodiesterase III (PDE-3) inhibitors are inotropes used to treat congestive heart failure (HF). Previous studies showed PDE-3A mRNA levels were reduced in the left ventricle (LV) in dogs subjected to pacing-induced HF. The present study evaluated a time-course for RV-specific changes in PDE-3A mRNAs and proteins after pacing for 3 wk (n=4) or in HF (4–5 wk;n=4–6). Total RNA from LV/RV tissues was isolated for Northern analyses; cytosolic and microsomal proteins were prepared for PDE-3A immunoblots. PDE-3A mRNAs (7–8 and 10 kb) were normalized against glyceraldehyde-3-phosphodehydrogenase (GAPDH) or ribosomal 18s with similar results.PDE-3A/GAPDH ratios in 3 wk were unchanged in LV, but significantly (p<0.05) reduced by 48% in RV vs unpaced controls (n=8). In contrast, PDE-3A (7–8kb)/GAPDH ratios were significantly reduced in HF by 50–59% in both ventricles. Consistent with mRNA levels, significant reductions in microsomal 135 kDa (93–96%) and cytosolic 120 kDa PDE-3A (57–69%) were seen in both ventricles in HF or in the RV at 3 wk; an LV-specific reduction (50%) in cytosolic 80 kDa PDE-3A in HF was also detected. In summary, RV-specific downregulation of PDE-3A mRNA/protein(s) at 3 wk suggests that hemodynamic rather than humoral mechanisms are responsible, and provides a molecular basis for the limited efficacy of milrinone in the progression of HF.

Identification of calcified intracardiac lesions using gradient echo MR imaging.

Gradient echo signal imaging (GEI) has expanded the clinical role of magnetic resonance (MR) imaging of the heart. The role of GEI to evaluate intracardiac calcified lesions was studied. All patients were imaged with both conventional spin echo (SE) techniques and GEI. The GEI demonstrated that calcific cardiac lesions exhibit magnetic susceptibility differences and produce marked hypointensity throughout the calcified area. All patients had echocardiographic and fluoroscopic evidence of cardiac calcification and surgical confirmation of calcified lesions. The SE MR was unable to define the intracardiac calcification. Gradient echo imaging may be a helpful adjunct in the complete definition of intracardiac calcific lesions. When profound signal void areas are detected on cardiac GEI studies, calcification should be suspected.

Use of the centrifugal flow pump for vena caval shunting.

We have used the Bio-Medicus centrifugal flow pump for vena cava shunting during surgical resection of renal cell carcinoma with extension of the tumor into the inferior vena cava. The active shunt can provide optimal blood return to the heart to promote hemodynamic stability, help provide an isolated field for resection of the involved kidney and its tumor extension into the vena cava, and avoid use of full-dose heparin to minimize blood loss in this extensive operation.

Endothelial Loss due to Leukocytes in Canine Experimental Vein-to-Artery Grafts

Vein-to-artery grafts develop areas of endothelial loss with fibrin and leukocytes which lead to early thrombosis and may lead to subsequent atherosclerosis of the graft. En face monolayers were prepared which removed greater than 90% of vascular intima. Unevenly distributed leukocytes and endothelial cells were counted using a standardized sampling of calibrated oil immersion fields of 0.01 mm2. Nongrafted veins had 14 +/- 1 evenly arranged endothelial cells per field without gaps or leukocytes, while 10-min grafts had 13 +/- 2 with rare leukocytes. Four-hour grafts from normal dogs had 9 +/- 2 endothelial cells with gaps and 97 +/- 37 neutrophils and 44 +/- 25 monocytes. Leukopenic dogs (vinblastine-treated) had normal numbers of endothelial cells (14 +/- 1) with scanty leukocytes. We conclude that leukocytes cause endothelial loss in vein-to-artery grafts that can be prevented by intense leukopenia. This may lead to practical approaches to protecting such grafts in humans.

Uupregulation of High Affinity Cyclic AMP Phosphodiesterase (PDE) Genes Following BALloon Catheter Deendothelialization (Bal) in Rat Aorta

P75 Inhibitors of PDE 3 and/or PDE4 block smooth muscle cell (SMC) proliferation/migration in vitro and reduce restenosis. To evaluate chronic regulation of SMC PDEs, rats were subjected to BAL. At several times after BAL (30 min to 10days/10D), medial SMC were isolated from the thoracic aortae. Tissues were fractionated for total RNA (analyzed by Northern blots/ RNAase protection) or cytosolic protein (Western blots or low Km [100 nM] cAMP PDE activity). BAL-dependent increases in PDE4B mRNA were biphasic: 2.7-fold at 1hr, which declined by 24hr below control values, followed by 2-3-fold increases by 4-7D (p<0.05 vs controls, n=3-6). PDE4B and c-myc mRNAs were selectively superinduced in cycloheximide-treated rats. Despite modest changes in PDE3 mRNAs, both 80 and 120 kDa PDE3A proteins were detected and only the 80kDa increased 7D post-BAL (10-fold increase, p<0.05, n=6). PDE4B2 (80kDa) persistently increased 2.5-3-fold (p<0.05, n=4-6) from 24 hr to 10D post-BAL, while 2-fold increases in PDE4D3 (90kDa) and PDE4B1 (104kDa) were evident at 24hr or 7D, respectively. PDE activity increased 50-60% (p<0.05; n=4) at 24 hr and 7D after BAL. Thus PDE4B resembles an immediate-early gene. Selective induction of the PDE4 family is associated with 2 waves of SMC proliferation in vivo, the latter of which is also accompanied by induction of PDE3A/80kDa. Upregulation of specific SMC PDEs following angioplasty represents an important response to injury that may be a useful therapeutic target in vascular disease.