Excluding the effect of foreign exchange, total Cardiovascular and Neuromodulation Products sales grew 5.0 percent; the increase was driven by double-digit growth in Electrophysiology, Heart Failure and Structural Heart. The growth in Electrophysiology reflects higher sales of cardiac diagnostic and ablation catheters in both the U.S. and internationally. In January 2019, Abbott announced U.S. FDA approval of its TactiCath® contact force ablation catheter, Sensor Enabled™, which is designed to help physicians treat atrial fibrillation, a form of irregular heartbeat.
In Heart Failure, growth was driven by rapid market adoption in the U.S.of Abbott’s HeartMate 3® Left Ventricular Assist Device following FDA approval in October 2018 as a destination (long-term use) therapy for people living with advanced heart failure. In March 2019, Abbott announced new data from its MOMENTUM 3 clinical study, the largest randomized controlled trial to assess outcomes in patients receiving a heart pump to treat advanced heart failure, which demonstrated HeartMate 3 improved survival and clinical outcomes in this patient population.
Growth in Structural Heart was broad-based across several areas of the business, including MitraClip®, Abbott's market-leading device for the minimally invasive treatment of mitral regurgitation (MR), a leaky heart valve. During the first quarter of 2019, Abbott received U.S. FDA approval for a new, expanded indication for MitraClip to treat clinically significant secondary MR as a result of underlying heart failure. This new indication expands the number of people with MR that can be treated with the MitraClip device. In July 2019, Abbott received U.S. FDA approval of the next generation of its MitraClip device, which includes a new leaflet grasping enhancement, an expanded range of clip sizes and facilitation of procedure assessment in real time to offer doctors further options when treating mitral valve disease.
In Vascular, excluding the effect of foreign exchange, revenues were basically flat as the 1.4 percent increase in coronary and endovascular product sales, which includes drug-eluting stents, balloon catheters, guidewires, vascular imaging/diagnostics products, vessel closure, carotid and other coronary and peripheral products, was offset primarily by a reduction in royalty revenue. In Rhythm Management, the 1.2 percent decline in revenues, excluding the effect of foreign exchange, reflects a 6.3 percent decrease in U.S. sales partially offset by a 4.0 percent increase in international sales. The 4.3 percent decline in Neuromodulation sales, excluding the effect of foreign exchange, reflects a 5.4 percent decline in U.S. sales.
The gross profit margin percentage was 52.4 percent for the third quarter of 2019 compared to 51.5 percent for the third quarter of 2018. The gross profit margin percentage was 52.3 percent for the first nine months of 2019 compared to 50.9 percent for the first nine months of 2018. The increase in the first nine months of 2019 primarily reflects the favorable comparison versus the prior year from lower intangible amortization expense, and integration and restructuring costs in 2019.
Research and development expenses increased by $22 million, or 3.7 percent, in the third quarter of 2019 and increased by $107 million, or 6.1 percent, in the first nine months of 2019 compared to the prior year. The increase in the third quarter of 2019 reflects higher R&D spending in various businesses and the acquisition of an R&D asset. The increase in R&D spending in the first nine months of 2019 primarily reflects higher spending on the acquisition of R&D assets. In the first quarter of 2019, in conjunction with the acquisition of Cephea Valve Technologies, Inc., Abbott acquired an R&D asset valued at $102 million, which was immediately expensed. During the first nine months of 2018, Abbott acquired R&D assets valued at $43 million, which were immediately expensed. The increase in R&D expense during the first nine months of 2019 was also driven by higher R&D spending in various businesses, including Cardiovascular and Neuromodulation, partially offset by the favorable effect of foreign exchange. For the nine months ended September 30, 2019, research and development expenditures totaled $811 million for the Cardiovascular and Neuromodulation Products segment, $419 million for the Diagnostic Products segment, $142 million for the Nutritional Products segment and $137 million for the Established Pharmaceutical Products segment.
Selling, general and administrative (SG&A) expenses increased 2.7 percent in the third quarter and decreased 0.4 percent in first nine months of 2019. The increase in the quarter is primarily due to higher selling and marketing costs to drive continued growth across various businesses, partially offset by the favorable effect of foreign exchange and lower acquisition-related integration costs. The decrease in the first nine months of 2019 is due primarily to the favorable effect of foreign exchange and lower acquisition-related integration costs, partially offset by higher selling and marketing costs to drive continued growth across various businesses.
Restructuring Plans
The results for the first nine months of 2019 reflect charges under approved restructuring plans as part of the integration of the acquisitions of St. Jude Medical and Alere or as part of various cost reduction programs. Abbott recorded employee related severance and other charges of $101 million in the first nine months of 2019 related to these initiatives, of which $28 million is recognized in Cost of products sold, $12 million is recognized in Research and development and $61 million is recognized in SG&A expense. See Note 7 to the financial statements, “Restructuring Plans,” for additional information regarding these charges.